The most recent hypothesis of relationships in Conostegia based on DNA sequences from four chloroplast and two nuclear ribosomal regions, resolved the genus as paraphyletic with species of Clidemia and Miconia nested inside (Kriebel et al. 2015). Nonetheless, all species of Conostegia fall in a major clade regardless of the type of analysis conducted (concatentation vs. concordance). A summary of the relationships within Conostegia based on the hypothesis derived from the concatenated analysis is presented in Figure 1. These results also show the paraphyly of Schnell’s (1996) subgenus Conostegia since the species of his subgenus Lobatostigma form a clade nested inside of it. With respect to Schnell’s sectional classification of subgenus Conostegia his groups are not monophyletic except sections Parvistigma and Tomentostegia. For this reason, the subgeneric classification adopted here includes only sections corresponding to the three major clades in Conostegia identified by both concatentation and concordance analyses and proposed as Conostegia sections Australis, Conostegia, and Geniculatae, respectively (Fig. 1). Section Australis has calyptrate calyces that break at one side, abundant sclereids in the hypanthium, mucilage in the ovary, exserted styles, lack of filament geniculation, and all but one species sampled lack a vascular cylinder in the style. Even then, the cylinder in Conostegia ortizae has a single vascular bundle (unlike species in section Conostegia which have more). Species in section Conostegia are almost unique within the genus in that their styles are not exserted (flowers not herkogamous). This short style is only shared with some populations of C. monteleagreana in section Australis and the clade composed of C. osaensis, C. plumosa, C. speciosa, C. subcrustulata and C. xalapensis within section Geniculatae. An additional character almost unique to section Conostegia and not shared with any of the latter short-styled taxa is the presence of a vascular cylinder within the style. Additional characteristics of section Conostegia include the abundant sclereids in the hypanthium and presence of ovary mucilage (shared with section Australis). Based on anatomy and morphology, section Australis and section Conostegia are quite similar. These two sections also share the frequent pleiostemonous condition and the lack of an evident filament geniculation. The two groups differ in that species of section Conostegia do not have exserted styles, and all have vascular cylinders in the style whereas species of section Australis have exserted style and all but one species lack the vascular cylinder in the style. Lastly, many species in section Australis have an “anther shoulder” that species of section Conostegia lack. Section Geniculatae can be recognized by the lack of calyptra in most of its species. Only the following taxa have a calyptra: C. cinnamomea, C. osaensis, C. plumosa, C. speciosa, C. subcrustulata, and C. xalapensis. The calyptra of these species differs from those of the other two sections in that they lack sclereids. Additional characteristics of section Geniculatae include the filament geniculation, the exserted style (in most of its species), small flower size, diplostemonous flowers of most of its species, and the frequently papillose seed testa. Lastly, it is noteworthy that many of the species in this section have leaves that are strongly plinerved and frequently asymmetric. Also, see the Biogeography section for remarks on the marked geographical patterns at the sectional level.

Figure 1. 

Infrageneric classification in Conostegia next to the recently generated molecular phylogenetic hypothesis of Conostegia. Colors show the classification proposed by Schnell (1996). To the right of the phylogeny is the sectional classification proposed here. The phylogeny is a slightly modified version of the majority rule consensus tree derived from a Bayesian analysis of DNA sequences from four chloroplast regions and two nuclear ribosomal spacers (Kriebel et al. 2015) pruned to one accession per species.

Chromosome counts have been reported for the following 13 species of Conostegia: C. arborea, C. colliculosa, C. consimilis, C. galdamesiae, C. hammelii, C. icosandra, C. montana, C. oerstediana, C. setosa, C. subcrustulata, C. superba, C. schlimii, and C. xalapensis (Solt and Wurdack 1980, Almeda and Chuang 1992, Schnell 1996, Almeda 2013). In all reported counts the haploid number was n=17, which is believed to be the base number of the tribe Miconieae (Almeda 2013).

Of the three main clades (sections) of Conostegia, the smallest one, Australis, is noticeable for its species being primarily South American, i.e., C. apiculata, C. centronioides, C. dentata, C. extinctoria, C. lancifolia, C. ortizae and C. rubiginosa. This is almost the only clade to contain species endemic to South America except for C. ecuadorensis and C. foreroi of section Geniculatae. Other species of section Australis (e.g. C. lasiopoda and C. tenuifolia) reach southern Central America and are common in that region, but none of the species in section Australis ranges beyond Nicaragua and none are present in the Caribbean. The only species of section Australis to reach an oceanic island is C. lasiopoda, which occurs on Cocos Island in the Pacific Ocean.

Section Conostegia is mostly restricted to Central America and the Caribbean. Roughly speaking there are three distinct areas where endemic species of this section occur. The area with the most endemics is southern Central America (Costa Rica and Panama). The mountains in these two countries include the volcanic ranges in Costa Rica and the Talamanca mountains that start in Costa Rica and end in Panama, harboring endemics such as C. bigibbosa, C. chiriquensis, C. fragrantissima, C. macrantha, C. micrantha, C. muriculata, C. oerstediana, C. pittieri, C. rhodopetala, and C. vulcanicola. Some of these species reach their northernmost distribution on volcanoes of Nicaragua and some also reach the lowlands of these three countries. The second area of endemism for species of section Conostegia is in northern Central America, both in the mountains of southern Mexico as well as in some lower-elevation and drier valleys. Some of these northernmost endemics include C. arborea, C. caelestis, and C. jaliscana. Lastly the third area of endemism, which could potentially be divided into two, are the Caribbean islands of Hispaniola and Cuba (where the endemic C. lindenii grows), and the island of Jamaica where three endemics occur (C. balbisiana, C. procera, and C. pyxidata).

Section Geniculatae stands out biogeographically because most of its species (80%) are endemic to the southern Central American countries of Costa Rica and Panama. The rest of the species occur in northern Central America with endemics of that area including C. fulvostellata, C. oligocephala, and C. plumosa. Other species of section Geniculatae (e.g. C. speciosa, C. subcrustulata, and C. xalapensis) are more-or-less widespread in Central America reaching South America. Just like in section Australis, only one species of section Geniculatae (i.e., C. ombrophila) reaches an oceanic island, i.e. Cocos Island in the Pacific.

Ongoing work in the tribe Miconieae to obtain a dated phylogeny will provide a time calibrated hypothesis that will enable a thorough biogeographical analysis of Conostegia.

Leaves and floral buds were fixed in 70% ethanol in the field and at maximum two weeks later were brought into the lab and fixed in formalin-acetic acid-ethanol (FAA; 3.7% formaldehyde; 5% glacial acetic acid; 50% ethanol), vacuum-infiltrated overnight, and then stored in 70% ethanol. For light microscopy, fixed material was dehydrated through an alcohol-toluene series in a Leica TP-1020 automatic tissue processor, and embedded in Paraplast X-tra (Fisher Healthcare, Houston, Texas, USA). The samples were sectioned at 10 µm with an AO Spencer 820 rotary microtome (GMI Inc. Minnesota, USA). Sections were stained with Johansen’s safranin (Johansen 1940) (2% w/v in 50% ethanol) and 0.5% Astra Blue in 2% tartaric acid w/v in distilled water (Maácz and Vágás 1961; Kraus et al. 1998) and mounted in Permount (Fisher Scientific, Pittsburgh, Pennsylvania, USA). Sections were viewed and digitally photographed with a Zeiss Axioplan compound microscope equipped with a Nikon DXM1200C digital camera with ACT-1 software.

To thoroughly document trichomes, floral parts, and seeds, Scanning Electron Microscopy (SEM) was used. For the study of floral parts, flowers collected in the field were brought to the lab and transferred to acetone via an ethanol-acetone series, and then dried by critical point, mounted on aluminum stubs with adhesive tabs (Electron Microscopy Sciences, Hatfield, PA, USA), sputter coated with gold palladium in a Hummer 6.2 sputter coater (Anatech, Springfield, VA, USA), and examined and photographed in a Jeol JSM-5410 LV Scanning Electron Microscope operated at 10 kV. Seeds were cleaned in water prior to sputter coating and SEM.

Both photographs of living plants and dissections of material in spirit are used to illustrate the species treated in this revision. For preserved material, floral structures were photographed under a Nikon SMZ1500 stereoscope equipped with a Nikon DXM1200F camera connected to a computer and using the software ACT-1. The plates were prepared with GIMP (The GNU Image Manipulation Program).

The flowering phenology of species of Conostegia was tallied using herbarium label data. In total, the flowering time for 1420 specimens was recorded. To best visualize in a comparative manner the phenology of each species, circular histograms were produced (Figs 8–14). This assessment of phenology should be taken with caution since it is based on herbarium specimens which can often be the result of easy accessibility to collecting sites and other collecting biases such as sampling error and good weather conditions. Furthermore, realistic patterns of phenology are obscured for broadly distributed species as well as local patterns, which are best studied at the population level. Schnell (1996) reported a pattern present in species such as C. bracteata, C. montana, C. setifera, and perhaps C. balbisiana in which flowering begins around March and finishes in September. Schnell (1996) called this an example of the normal “out-of-season low-frequency flowering” which might be favored in individuals in high light environments. Schnell (1996) also noted the year-long flowering of weedy species and hypothesized that these longer flowering times might be selected for longer fruiting seasons which might permit more colonization. A second possible non-exclusive explanation proposed by Schnell (1996) is that because of their weedy habit they tend to receive more light allowing them more energy for reproduction. Lastly, Schnell (1996) suggested the possibility that there are collection biases and that these habitats are more frequently visited by collectors. In addition, some species show very marked seasonality. For example, Conostegia caelestis and C. osaensis only flower between March and June. Conostegia oligocephala has a similarly narrow pattern being recorded in flower from May to July. Conostegia brenesii in the cloud forests of Costa Rica only flowers during the rainy season from July through September. Conostegia grayumii, C. incurva, C. pendula, C. povedae, and C. subpeltata appear to follow a similar pattern of rainy-season flowering from July through October. Another possible pattern includes C. allenii and C. calocoma both of which only flower from January through July.

Figure 8. 

Phenology in species of Conostegia. White slices denote flowering specimens and gray slices fruiting specimens. The size of the slice represents the relative amount of specimens from the total which was blooming or fruiting in that month.

Figure 9. 

Phenology in species of Conostegia. White slices denote flowering specimens and gray slices fruiting specimens. The size of the slice represents the relative amount of specimens from the total which was blooming or fruiting in that month.

Figure 10. 

Phenology in species of Conostegia. White slices denote flowering specimens and gray slices fruiting specimens. The size of the slice represents the relative amount of specimens from the total which was blooming or fruiting in that month.

Figure 11. 

Phenology in species of Conostegia. White slices denote flowering specimens and gray slices fruiting specimens. The size of the slice represents the relative amount of specimens from the total which was blooming or fruiting in that month.

Figure 12. 

Phenology in species of Conostegia. White slices denote flowering specimens and gray slices fruiting specimens. The size of the slice represents the relative amount of specimens from the total which was blooming or fruiting in that month.

Figure 13. 

Phenology in species of Conostegia. White slices denote flowering specimens and gray slices fruiting specimens. The size of the slice represents the relative amount of specimens from the total which was blooming or fruiting in that month.

Figure 14. 

Phenology in species of Conostegia. White slices denote flowering specimens and gray slices fruiting specimens. The size of the slice represents the relative amount of specimens from the total which was blooming or fruiting in that month.

Species of Conostegia are all terrestrial shrubs or trees. Some of the tallest trees in the tribe Miconieae are found in Conostegia, with C. osaensis reaching about 25 meters in height. Schnell (1996) noted a bimodal distribution of height classes and growth forms in which species were either large trees able to compete with canopy trees such as (e.g., C. volcanalis and C. rufescens), or fast-growing shrubs that seldom grow higher than 2–3 m. He further suggested that the shrubby growth habit had evolved more than once. In addition, I have observed C. rufescens growing both as a large tree and as a shrub. The latter was observed in Cerro Jefe, Panamá, and in the lower parts of Braulio Carrillo National Park in Costa Rica. In Braulio Carrillo, which harbors forests over a wide elevational range, I also observed C. rufescens as a taller tree in the cloud forest. The pattern of tall trees is especially evident in the giant stigma group with a clear independent origin in C. osaensis and probably also in C. schlimii, which can also become a tall tree. The trunk of some species such as C. bernoulliana and C. oerstediana, can have flaky bark but in most taxa it is smooth. The smallest species are those previously described in Clidemia, such as C. subpeltata and C. trichosantha, which grow in the understory mostly of cloud forests. Twigs vary from terete and slender to somewhat quadrangular and robust. Particularly the species with thick twigs such as C. bigibbosa and C. macrantha, tend to have lenticels on the nodes.

Leaves are opposite and generally decussate as is the case in most species in the family. In one species, Conostegia henripittieri, they are always strongly anisophyllous. Most species of sections Australis and Conostegia have leaves with nerved venation and species in section Geniculatae tend to be strongly plinerved. Variation in leaf morphology among species is most evident in section Geniculatae with one peltate species (C. peltata) and a subpeltate species (C. subpeltata), as well as species with sessile leaves (C. dissitiflora) or strongly attenuate leaf bases (C. consimilis). In addition, many species of section Geniculatae tend to have asymmetric leaf venation. In C. grayumii for example, almost every leaf is asymmetrical at the base.

Thirty leaves of 26 species within Conostegia were collected in the field, fixed in FAA, and then sectioned as explained above. Leaves of all Conostegia studied are hypostomatic. The cuticle is generally inconspicuous but sometimes can be relatively thick as in C. rhodopetala (Fig. 15). The mesophyll is dorsiventral (Figs 15, 16), and druses were present in all species, usually near the adaxial or abaxial leaf epidermis. The size of the druses varies. Some species such C. tenuifolia have more space in the mesophyll. Leaf thickness varied but in general leaves were thinner in section Geniculatae (Fig. 17). At least two types of coriaceous leaves were found. Populations of C. montana from Cerro Jefe, Panama, have a very thick mesophyll and are the most evidently coriaceous leaves encountered in this survey. The other thick-leaved species were found to have a hypodermis one cell layer thick. This hypodermis is found only in C. montelagreana in section Australis and in the species of the giant stigma clade (species sampled were C. bigibbosa, C. icosandra, C. oerstediana, and C. pittieri) where it appears to have evolved in their common ancestor (Fig. 15). Mentink and Baas (1992) reported the presence of a hypodermis in C. subcructulata but sections done for this study failed to locate a hypodermis in that this species (Fig. 16). In the Melastomataceae the function of the hypodermis has been suggested to be related to water storage in epiphytic species (Reginato et al. 2009) or protecting the palisade parenchyma against solar radiation in terrestrial species (Ely et al. 2005). The spongy mesophyll was usually not lignified except in some species, such as C. ombrophila and C. schlimii.

The petioles in Conostegia bigibbosa and some Costa Rican and Guatemalan populations of C. montana have two protuberances at the apex of the petiole on the abaxial surface. Scanning electron micrographs of these protuberances evidenced a glabrous area with some stomata suggesting that they might be extrafloral nectaries. However, anatomical sections in C. bigibbosa did not indicate the presence of carbohydrates. Cross sections of petioles show variation in shape from rounded to somewhat heart shaped, grooved or flat adaxially as in C. consimilis, C. schlimii, C. tenuifolia, and C. bernoulliana (Fig. 16). Five to nine amphicribal bundles are present, forming an interrupted arc. The lowermost bundles tend to be larger as in C. rufescens, C. subcrustulata and C. schlimii, (Fig. 16). Smaller bundles are sometimes present inside the primary arc as in C. bernoulliana, C. bracteata, C. rufescens, and C. tenuifolia (Fig. 16). Petioles are mostly unlignified but sclereids are present in some species, but besides the sclereids, petioles were mostly unlignified. Some lignification of the petiole was observed in C. rufescens and C. schlimii.

Figure 15. 

Leaf anatomy in Conostegia A C. lasiopoda (R. Kriebel 5780) B C. monteleagreana (R. Kriebel s. n.) C C. tenuifolia (R. Kriebel 5773) D C. bigibbosa (R. Kriebel 5771) E C. bracteata (R. Kriebel 5816). F C. brenesii (R. Kriebel 5546) G C. caelestis (R. Kriebel 5617) H C. bernoulliana (R. Kriebel 5772). I C. montana (R. Kriebel 5548) J C. montana (R. Kriebel 5662) K C. oerstediana (R. Kriebel 5627) L C. pittieri (R. Kriebel 5543) M C. rhodopetala (R. Kriebel 5542). N C. rufescens (R. Kriebel 5524) O C. setosa (R. Kriebel 5813) P C. fraterna (R. Kriebel 5774) Q C. hammelii (R. Kriebel 5539) R C. ombrophila (R. Kriebel s.n.) S C. subcrustulata (R. Kriebel 5808). T C. xalapensis (R. Kriebel 5817) U C. calocoma (R. Kriebel s. n.). Scale bar: 100 µm.

Figure 16. 

Leaf and petiole anatomy in Conostegia. A C. grayumii (R. Kriebel 5807) B C. consimilis (R. Kriebel 5811) C C. oligocephala (R. Kriebel 5575) D C. schlimii (R. Kriebel 5776) E C. lasiopoda (R. Kriebel 5780) F C. tenuifolia (R. Kriebel 5773) G C. monteleagreana (R. Kriebel s. n.) H C. bigibbosa (R. Kriebel 5771). I C. bracteata (R. Kriebel 5816). J C. bernoulliana (R. Kriebel 5772) K C. rufescens (R. Kriebel 5524). L C. setosa (R. Kriebel 5813) M C. subcrustulata (R. Kriebel 5808). N C. grayumii (R. Kriebel 5807) P C. consimilis (R. Kriebel 5811) O C. schlimii (R. Kriebel 5776). Scale bar: 100 μm (A–D); 1 mm (E–O).

Figure 17. 

Boxplots of leaf thickness by section of Conostegia. The outlier in section Conostegia is a population of C. montana from Cerro Jefe, Panama. Units in microns.

Three types of domatia occur in Conostegia. In two species, C. dentata and C. setosa, the domatia are of the formicarium type which house ants and are manifested as large swellings at the base of the leaf. The other two types are both mite domatia, present at the base of the leaf on the abaxial side at the point of divergence between the midvein and the primary lateral veins. The general classification of domatia used here follows Jacobs (1966). The first kind of mite domatium is the tuft mite domatium present in C. procera (Fig. 18). This species always has these structures, which are densely covered by stipitate stellate to dendritic trichomes. This type of domatium is also seen in some but not all specimens of C. hirtella. The second type of mite domatium is the pocket domatium which literally looks like a pocket formed by a membrane (Fig. 18). Some pocket domatia are further called vesicular domatia because they are inflated. Pocket domatia are present in only the clade comprising C. ecuadorensis, C. hammelii, and C. ombrophila. Among the species having pocket domatia, C. ecuadorensis is unique in that there are domatia present on both the innermost pair of primary lateral veins as well as on the outermost pair of lateral veins.

Figure 18. 

Types of domatia in Conostegia. A, B examples of pocket domatia C example of vesicular pocket domatium D example of tuft domatium A C. ecuadorensis (J. Betancur 3202) B Clidemia hammelii (L. Acosta 133). C C. ombrophila (R. Kriebel 5730) D C. procera (W. Maxon 8949). Scale bar: 1 mm.

Trichomes in Conostegia are quite diverse and variable (Fig. 19). This may not come as a surprise since trichomes in the Melastomataceae have been said to be the most diverse in the angiosperms (Wurdack 1986). In many cases trichome morphology is easy to describe, such as with simple or lepidote trichomes. Difficulty in describing trichomes arises with the vast variation in dendritic trichomes, and with the gradations from dendritic to stellate. Wurdack (1986) noted that all types in the family are multicellular and, of the 46 trichomes types he recognized, 14 were recorded in species of Conostegia sensu Schnell (1996). Schnell (1996) discussed trichomes in Conostegia extensively noting that Conostegia species tend to have a mixture of trichomes and that variation within a species is extensive. I have noted extreme variation in C. icosandra, which can be densely hirsute in the northern part of its range. Conostegia superba has also caused confusion because in the mainland specimens tend to be glabrous or almost so, but in the Dominican Republic they can be quite pubescent except for the floral buds. As noted by Schnell (1996), and even now taking the phylogeny into account, it is evident that similar trichomes have evolved independently within Conostegia. One example involves the interdependent evolution of stipitate trichomes of C. brenesii and C. caelestis. Schnell (1996) divided the trichomes of Conostegia into the three general groups recognizable based on the work on Wurdack (1986): 1) tiny glands, 2) elongate simple hairs, and 3) a series of eight potentially intergrading kinds of stellate and branching hairs. Schnell (1996) stated that continuous variation among these eight groups made it difficult to describe them. I agree with Schnell and recommend that into the future, a quantitative method should be developed to describe and perhaps discretize these complicated dendritic to stellate trichomes. In the meantime, I have chosen to document the trichomes in a similar way as Wurdack (1986) did, with extensive Scanning Electron Micrographs (Figs 20–33). Apparently all taxa have minute glands on the abaxial leaf surface, and their shape is variable and may prove to be taxonomically informative. Their small size makes them difficult to describe, especially in species with dense pubescence on the leaf abaxial surfaces. To compliment Wurdack’s (1986) initiative for Conostegia, I placed special attention on documenting these minute glands as much as possible.

Figure 19. 

Examples of trichome types in Conostegia. A C. dentata (J. Cuatrecasas 17668) B C. bracteata (M. Hopkins 22) C C. ortizae (D. Penneys 1857) D C. superba (W. Judd 6521) E C. extinctoria (H. David 1227). F C. brenesii (R. Kriebel 4907) G C. subcrustulata (L. Williams 27545) H C. rufescens (D. Penneys 1792) I C. consimilis (A. Jiménez 2326) J C. osaensis (R. Aguilar 12890).

Figure 20. 

Trichomes in Conostegia. A–B C. allenii (G. de Nevers 7207) C–D C. ecuadorensis (J. Betancur 3202) E–F C. foreroi (F. Almeda 10336) G–H C. fraterna (R. Kriebel 5774). Scale bar: 100 µm.

Figure 21. 

Trichomes in Conostegia A–B C. hammelii (L. Acosta 133) C–D C. ombrophila (R. Kriebel 5730) E–F C. henripittieri (R. Kriebel 5757) G–H C. subpeltata (R. Kriebel 5347). Scale bar: 100 µm.

Figure 22. 

Trichomes in Conostegia. A C. trichosantha (F. Almeda 6491). B C. cinnamomea (T. Croat 6542) C–D C. brenesiana (J. Taylor 17646) E–F C. calocoma (R. Kriebel 5484) G–H C. centrosperma (R. Kriebel 5690). Scale bar: 100 µm.

Figure 23. 

Trichomes in Conostegia A–B C. colliculosa (R. Kriebel 5721) C–D C. dissitiflora (R. Kriebel 5378) E–F C. dissitinervia (R. Kriebel 5377) G–H C. friedmaniorum (R. Kriebel 5721). Scale bar: 100 µm.

Figure 24. 

Trichomes in Conostegia A–B C. galdamesiae (R. Kriebel 5836) C–D C. grayumii (T. McDowell 199) E–F C. incurva (W. Alverson 2747) G–H C. jefensis (R. Kriebel 5680). Scale bar: 100 µm.

Figure 25. 

Trichomes in Conostegia A–B C. consimilis (A. Jimenez 2326) C–D C. oligocephala (R. Kriebel 8575) E–F C. osaensis (R. Aguilar 12890) G–H C. papillopetala (R. Kriebel 5718). Scale bar: 100 µm.

Figure 26. 

Trichomes in Conostegia A–B C. peltata (R. Kriebel 5658) C–D C. povedae (F. Oviedo 1908) E–F C. schlimii (T. G. Yuncker 8780) G–H C. shattuckii (R. Kriebel 5688). Scale bar: 100 µm.

Figure 27. 

Trichomes in Conostegia A–B C. bracteata (M. Hopkins 22) C–D C. brenesii (R. Kriebel 4907) E–F C. caelestis (A. Molina 8352) G–H C. cuatrecasii (R. Kriebel 5681). Scale bar: 100 µm.

Figure 28. 

Trichomes in Conostegia A–B C. extinctoria (H. David 1227) C–D C. icosandra (R. Kriebel 5580) E–F C. jaliscana (F. Almeda 2450) G–H C. ortizae (D. Penneys 1857). Scale bar: 100 µm.

Figure 29. 

Trichomes in Conostegia. A–B C. lasiopoda (J. Cuatrecasas 16953) C–D C. superba (W. Judd 6521) E–F C. macrantha (R. Kriebel 5406) G–H C. micrantha (R. Espinoza 1739). Scale bar: 100 µm.

Figure 30. 

Trichomes in Conostegia A–B C. montana (R. Kriebel 5662) C–D C. monteleagreana (R. Kriebel 5747) E–F C. oerstediana (R. Kriebel 5408) G–H C. pittieri (R. Kriebel 5400). Scale bar: 100 µm.

Figure 31. 

Trichomes in Conostegia A–B C. plumosa (D.W. Stevens 25247) C–D C. speciosa (S. B. Robbins 6173) E–F C. subcrustulata (L. O. Williams 27545) G–H C. xalapensis (D. Penneys 1758). Scale bar: 100 µm.

Figure 32. 

Trichomes in Conostegia A–B C. polyandra (P. Acevedo 6905) C–D C. procera (W. Maxon 8949) E–F C. rhodopetala (R. Kriebel 5462) G C. rufescens (D. Penneys 1792) H C. rufescens (R. Kriebel 5687). Scale bar: 100 µm.

Figure 33. 

Trichomes in Conostegia. A C. cuatrecasii (J. Cuatrecasas 17668). B C. setosa (M. Tirado 529) C–D C. superba (R. Kriebel 5582) E–F C. tenuifolia (R. Moran 7950) G–H C. volcanalis (R. Kriebel 5565). Scale bar: 100 µm.

All species with discolorous leaves are in section Geniculatae. However, this character has evolved independently a number of times within the section and not all discolorous leaves are the result of the same type of trichome. In some cases such as C. xalapensis the dense indument on the abaxial surface is made up of stellate trichomes with long, thin arms, whereas in closely related C. osaensis they are lepidote. Many species in section Geniculatae have an orange-colored indument of dendritic to stellate trichomes on the stems, especially towards the apex, which are less common in the other sections or if present do not tend not to form a conspicuous orange covering.

Inflorescences in Conostegia are variable among species as in most clades of Miconieae (Michelangeli et al. 2004). Most species have terminal erect panicles with many flowers, but the inflorescence can be deflexed. In some species previously described in Miconia as well as in some species traditionally placed in Conostegia such as C. cinnamomea and C. muriculata, the inflorescence can be evidently deflexed. Axillary or pseudolateral inflorescences tend to have fewer, smaller flowers and are present mainly in those taxa previously described in Clidemia. Some small-flowered taxa do have many flowers such as C. consimilis. Bracts are usually early deciduous in sections Australis and sections Conostegia except in species such as C. monteleagreana which has persistent bracts subtending the floral glomerules. On the other hand, many species in section Geniculatae have bracts and bracteoles that are persistent and fused at the base, forming an inconspicuous nodal collar. Inflorescence branches are particularly thin, wiry, and delicate in several species within section Geniculatae such as C. cinnamomea, C. grayumii, and C. ombrophila. It was the presence of this type of inflorescence, as well as the similar bracteoles amongst other characters that prompted Schnell (1996) to state that the similarities between C. cinnamomea and C. brenesiana are “little short of uncanny, involving almost every character, even to minute details”.

Accessory branches in inflorescences are common in Conostegia, especially in taxa with relatively long terminal inflorescences. Although it is tempting to use the presence of these accessory branches in the systematics of the group, they are absent in some specimens, and in such cases it is difficult to tell if they fell off or were not there to begin with. Accessory branches are consistently absent in most species of section Geniculatae

Pedicels in Conostegia are also variable among species and major clades. In particular, species within section Conostegia can have quite long pedicels, as previously noted by Judd and Skean (1991). These pedicels can further elongate as the flowers develop into fruits. Pedicels are absent (flowers sessile) in some species such as C. monteleagreana in section Australis and C. colliculosa and C. povedae in section Geniculatae. Schnell (1996) noted that in certain species the pedicels are clustered at the end of the inflorescence branches. This clustering is such that the pedicels appear to arise from the axils of other pedicels hence naming these taxa in his section Axilliflora Schnell -ined (see figure of C. superba for an example). Species in this section do not form a clade as evidenced by the molecular phylogeny where C. monteleagreana falls in a different clade than C. cuatrecasii, C. rhodopetala, and C. superba (Fig. 1; see also Kriebel et al. 2015). Nonetheless, Schnell (1996) himself noted that the species of section Axilliflora did not sort out into clear groups.

Floral buds in calyptrate species of Conostegia are noticeable because of their calyx tends to fall as a unit at anthesis. Calyptrate calyces have arisen independently at least 15 times just in the Neotropical genera of the family and can be variously shaped (Fig. 34) (Schnell 1996). In the Miconieae, five genera have at least some species with a calyptra namely: Conostegia, Mecranium, Miconia, Tetrazygia and Tococa (Schnell 1996). Schnell (1996) considered floral buds to be the most useful structures not only to identify species at the generic level but also within Conostegia. In general terms their size and shape can be taxonomically useful, as well as the presence of warts or different types of indument on the hypanthium. The apex of the buds can also be helpful for identifying some species. An apiculate calyptra for example, is present in several distinct species from different geographical areas. In South America, the aptly named C. apiculata is readily distinguished. In northern Central America, the distinctively apiculate calyptra of C. arborea is not easily confused with others; the same is true of C. pittieri in the mountains of Costa Rica and western Panama, but in this area there are other species that can have somewhat apiculate calyptras (e.g. C. tenuifolia and C. rhodopetala).

Figure 34. 

Longitudinal sections of floral buds in Conostegia. A C. lasiopoda (R. Kriebel 5651) B C. monteleagreana (R. Kriebel 5747) C C. ortizae (D. Penneys 1857) D C. tenuifolia (R. Kriebel 5773) E C. bernoulliana (R. Kriebel 5540). F C. bigibbosa (R. Kriebel 5522) G C. bracteata (R. Kriebel 5806) H C. brenesii (R. Kriebel 5631) I C. montana (R. Kriebel 5593) J C. oerstediana (R. Kriebel 5627) K C. pittieri (R. Kriebel 5400) L C. rhodopetala (R. Kriebel 5542). M C. setosa (R. Kriebel 5731) N C. volcanalis (R. Kriebel 5565) O C. peltata (R. Kriebel 5658) P C. consimilis (R. Kriebel 5726) Q C. subcrustulata (R. Kriebel s.n.) R C. xalapensis (R. Kriebel 5619). Scale bar: 1 mm.

Phylogenetic and anatomical analyses have revealed that the calyptra evolved at least three times within Conostegia (Kriebel et al. 2015). This is a surprise because most workers previously thought the calyptrate calyx was shared by all species in the genus (Judd and Skean 1991; Schnell 1996) even referring to Conostegia as monophyletic without phylogenetic analyses of any kind (Judd and Skean 1991). Schnell (1996) did point to the possibility of the independent origin of the calyptra in C. cinnamomea, and stated that because these structures had evolved in the family there was possibly a selective force driving their evolution. The adaptive value of the calyptra remains unknown.

The calyptra of species in sections Australis and Conostegia are very similar in that they have conspicuous sclereids and no calyx teeth nor appendages (Fig. 35). The sclereids for the most part form a layer or two throughout the hypanthium and calyptra (Fig. 36). The main difference in the calyptra of these two sections is that in section Australis, the calyptra ruptures at one side and/or breaks into pieces in all species observed in the field (Fig. 37). In section Conostegia all evidence points to a cleanly circumscissle calyptra which Judd and Skean (1991) and Schnell (1996) believed was the case in all species of Conostegia. Independent origins of the calyptra are also seen in C. cinnamomea, which has a very thin calyptra, and in the clade comprised of C. osaensis, C. plumosa, C. speciosa, C. subcrustulata, and C. xalapensis. The calyptra in this latter clade lacks evident sclereids (Fig. 35). Although most species have a glabrous calyptra on the inside, three closely related species, i.e. C. plumosa, C. speciosa and C. xalapensis tend to have stellate trichomes inside the calyptra.

Figure 35. 

Calyptra and calyx teeth anatomy in Conostegia. A C. lasiopoda (R. Kriebel 5651) B C. monteleagreana (R. Kriebel 5747) C C. tenuifolia (D. Santamaria 8863) D C. brenesii (R. Kriebel 5631) E C. icosandra (R. Kriebel 5578) F C. montana (R. Kriebel 5544) G C. oerstediana (R. Kriebel 5627) H C. rufescens (R. Kriebel 5635) I C. superba (R. Kriebel 5582) J C. cinnamomea (R. Kriebel 5330) K C. speciosa (R. Kriebel 5677) L C. subcrustulata (R. Kriebel 5653) M C. xalapensis (R. Kriebel 5629) N C. friedmaniorum (R. Kriebel 5641) O C. schlimii (R. Kriebel 5614). Scale bars: 100 µm.

Figure 36. 

Ovary and hypanthium anatomy in Conostegia. A C. lasiopoda (R. Kriebel 5651) B C. monteleagreana (R. Kriebel 5747) C C. tenuifolia (D. Santamaria 8863) D C. brenesii (R. Kriebel 5631) E C. bracteata (R. Kriebel 5816) F C. cuatrecasii (R. Kriebel 5681) G C. icosandra (R. Kriebel 5578) H C. montana (R. Kriebel 5544) I C. oertsediana (R. Kriebel 5627) J C. setosa (R. Kriebel 5731) K C. superba (R. Kriebel 5582) L C. subcrustulata (R. Kriebel 5653). Scale bar: 500 µm.

Figure 37. 

Examples of calyptra dehiscence modes in Conostegia. A The cleanly circumscissle calyptra of C. setosa B The calyptra of C. tenuifolia ruptured at one side.

Within section Geniculatae, sclereids are mostly absent from the hypanthium and calyx. Some scattered sclereids are seen in the hypanthium of C. schlimii. In the floral anatomy of this section there are two general patterns that are absent in sections Australis and Conostegia. First, in several species of Geniculatae there is a lining of druses around the ovary (Fig. 38). Second, several species have a distinctly bicolored anatomy where the ovary tissue stains red, indicating some lignification but the rest of the hypanthium stains blue. In fewer specimens of section Geniculatae the hypanthium stains either totally red or entirely blue. For further anatomical differences between the ovaries in section Geniculatae and the other two sections Australis and Conostegia, see below under the Gynoecium section.

Figure 38. 

Ovary and hypanthium anatomy in Conostegia. A C. centrosperma (R. Kriebel 5690) B–D C. cinnamomea (R. Kriebel 5330) D under polarized light E C. dissitinervia (R. Kriebel 5377) F C. fraterna (R. Kriebel 5774) G–H C. grayumii (R. Kriebel 5807) H under polarized light I C. hammelii (R. Kriebel 5317) J C. ombrophila (R. Kriebel 3120) K C. schlimii (R. Kriebel 5614) L C. speciosa (R. Kriebel 5677) M C. trichosantha (R. Kriebel 5693). Scale bar: 500 µm except C and D: 100 µm.

Another unusual characteristic of the calyx of non-calyptrate species in section Geniculatae is the presence of an irregularly rupturing calyx in several of them (Fig. 39). This type of calyx is usually translucent. An example of the anatomy of the translucent calyx of C. friedmaniorum is presented next to the calyx of C. schlimii (a species without a translucent calyx) (Fig. 35). In all cases of species with this type of calyx, because it ruptures, the calyx lobes are irregularly shaped. The calyx teeth in calyptrate taxa are difficult to assess. In sections Australis and most calyptrate species of Geniculatae they appear to be totally absent and anatomical sections failed to reveal them. In C. cinnamomea, anatomical sections did evidence their presence. On the other hand, within the clade of C. osaensis, C. plumosa, C. speciosa, C. subcrustulata, and C. xalapensis one sees what seem to be inconspicuous calyx teeth in C. subcrustulata. Schnell (1996) included the aforementioned clade (except C. osaensis which was undescribed at the time) in his section Tomentostegia. In his description of that section, Schnell (1996) described the calyx lobes as fused and usually with free teeth or prolonged appendages. Assessing if these teeth or appendages are homologous to calyx teeth is difficult. To complicate things even more, in C. osaensis, which is the sister clade, the calyx teeth appear to be at the level of the torus as is common in species of section Geniculatae and more generally in most species of the tribe Miconieae.

Figure 39. 

Examples of irregularly rupturing calyces in Conostegia. A Flower bud from spirit collection of Conostegia subpeltata (R. Kriebel 3643) B Scanning electron micrograph of flower bud of C. papillopetala (R. Kriebel 5718). Scale bar: 1 mm.

Flowers in the species traditionally treated in Conostegia also stand out among genera of Miconieae because most of them are pleiostemonous, meaning that they have more than double the number of stamens than petals (Fig. 40). Other pleiostemonous taxa do exist within the Miconieae, but they are not thought to be closely related to Conostegia. There is one pleiostemonous species that has been named in Conostegia, C. inusitata, which appears not to be closely related to the other named taxa in the genus. This suggestion comes from a nuclear ribosomal DNA sequence (Kriebel, unpublished data) of an undescribed and closely related species to C. inusitata, which Schnell (1996) proposed as the new species Florbella wurdackii. The genus Florbella was proposed by Schnell to accommodate these two species, but it has yet to be published. Inclusion of this DNA sequence in phylogenetic analyses of Miconieae suggests it is more closely related to a clade of mostly Peruvian species of Miconia than to species of Conostegia. The concept of Conostegia included in the present treatment includes many diplostemonous species, particularly those previously described as Clidemia and Miconia. These diplostemonous taxa are almost completely restricted to section Geniculatae (Fig. 41), with a few diplostemonous taxa also found in section Conostegia (e.g. C. setosa).

Figure 40. 

Flowers in Conostegia section Australis (A–G), section Conostegia (H–T), and section Geniculatae (U–X). A C. centronioides (X. Cornejo 8160) B C. ortizae (D. Penneys 1857) C C. lasiopoda (R. Kriebel 5651) D C. monteleagreana (R. Kriebel 5354). E C. monteleagreana (P. Pedraza 1923) F C. polyandra (F. Almeda 10481) G C. tenuifolia (R. Kriebel 5773). H C. bracteata (R. Kriebel 5816). I C. brenesii (R. Kriebel 5631) J C. cuatrecasii (R. Kriebel 5673) K C. montana (R. Kriebel 5446) L C. rhodopetala (R. Kriebel 5542) M C. rufescens (R. Kriebel 5314) N C. setosa (R. Kriebel 5813) O C. superba (R. Kriebel 5582) P C. bigibbosa (R. Kriebel 5522) Q C. icosandra (R. Kriebel 5580) R C. macrantha (R. Kriebel 5406) S C. oerstediana (R. Kriebel 5408) T C. pittieri (R. Kriebel 5543) U C. cinnamomea (R. Kriebel 5330) V C. speciosa (R. Kriebel 5489) W C. subcrustulata (R. Kriebel 5333). C. xalapensis (R. Kriebel 5555). Flowers not to scale.

Figure 41. 

Flowers in Conostegia section Geniculatae. A Conostegia xalapensis (R. Kriebel 5619) B C. osaensis (R. Aguilar 10200) C C. allenii (R. Aguilar 13243) D C. foreroi (F. Almeda 10336) E C. fraterna (R. Kriebel 5774) F C. hammelii (R. Kriebel 5737) G C. ombrophila (R. Kriebel 3120) H C. subpeltata (R. Kriebel 5347) I C. trichosantha (R. Kriebel 5693) J C. centrosperma (R. Kriebel 5690) K C. dissitiflora (R. Kriebel 5070) L C. dissitinervia (R. Kriebel 5046) M C. friedmaniorum (R. Kriebel 5641) N C. galdamesiae (R. Kriebel 5736) O C. grayumii (R. Kriebel 5807) P C. consimilis (R. Kriebel 5466) Q C. papillopetala (R. Kriebel 5718) R C. peltata (R. Kriebel 5658). S C. povedae (F. Oviedo 1215). T C. schlimii (R. Kriebel 5095). Flowers not to scale.

The corolla in Conostegia varies dramatically in size, shape and number of parts among species (Figs 42, 43) and sometimes also within species. Petal number can range from 4 to 12. Petal shape is quite variable among species and in general they tend to be asymmetric with notable exceptions e.g. in some species in section Geniculatae. Many species especially in section Australis and section Conostegia tend to have strongly asymmetrical petals. The posture of the petals is usually spreading with some species (particularly small-flowered ones) having reflexed petals. Petals are always imbricate in bud and overlap in a counter-clockwise fashion (Schnell 1996). At anthesis petals are usually imbricate in large flowered taxa but the overlap tends to decrease as the flowers get smaller. Petal margins are for the most part entire but in many large-flowered taxa they can have a more membranous texture on one side (Fig. 44). Petal apices are mostly rounded, truncate, or emarginate, and in a few species they can be narrowly rounded to acute. One species (C. consimilis) was originally described in the genus Leandra because of its acuminate petals. Petal bases are not evidently clawed, except in C. schlimii.

Figure 42. 

Flowers of Conostegia from specimens collected in spirit with a longitudinal section at their side. A C. lasiopoda (R. Kriebel 5651) B C. monteleagreana (R. Kriebel 5747) C C. tenuifolia (R. Kriebel 5773) D C. bernoulliana (R. Kriebel 5540) E C. bracteata (R. Kriebel 5816) F C. brenesii (R. Kriebel 5631). G C. cuatrecasii (R. Kriebel 5673) H C. icosandra (R. Kriebel 5580) I C. montana (R. Kriebel 5751) J C. montana (R. Kriebel 5593) K C. oerstediana (R. Kriebel s.n.) L C. pittieri (R. Kriebel 5400) M C. rufescens (R. Kriebel 5314) N C. setosa (R. Kriebel 5731) O C. superba (R. Kriebel 5582). Scale bar: 1 mm.

Figure 43. 

Flowers of Conostegia from specimens collected in spirit with a longitudinal section at their side. A C. brenesiana (R. Kriebel 3665) B C. centrosperma (R. Kriebel 5690) C C. cinnamomea (R. Kriebel 5330) D C. consimilis (R. Kriebel 5726) E C. friedmaniorum (R. Kriebel 5641) F C. galdamesiae (R. Kriebel 5736) G C. hammelii (R. Kriebel 5737) H C. papillopetala (R. Kriebel 5718) I C. peltata (R. Kriebel 5658) J C. schlimii (R. Kriebel 5614) K C. shattuckii (R. Kriebel 5681) L C. speciosa (R. Kriebel 5677) M C. subcrustulata (R. Kriebel s. n.) N C. trichosantha (R. Kriebel 5693) O C. xalapensis (R. Kriebel 5619). Scale bar: 1 mm.

Figure 44. 

Petals of Conostegia to scale. a C. lasiopoda (R. Kriebel 5651) b C. monteleagreana (R. Kriebel 5747) c C. ortizae (D. Penneys 1857) d C. tenuifolia (R. Kriebel 5773) e C. bernoulliana (R. Kriebel 5540) f C. bigibbosa (R. Kriebel 5522) g C. bracteata (R. Kriebel 5816) h C. brenesii (R. Kriebel 5631) i C. cuatrecasii (R. Kriebel 5673) j C. fragrantissima (R. Kriebel 3174) k C. icosandra (R. Kriebel 5580) l C. macrantha (R. Kriebel 5406) m C. montana (R. Kriebel 5751) n C. montana (R. Kriebel 5593) o C. oerstediana (R. Kriebel 5627) p C. pittieri (R. Kriebel 5400) q C. rhodopetala (R. Kriebel 5542) r C. rufescens (R. Kriebel 5627) s C. setosa (R. Kriebel 5731) t C. superba (R. Kriebel 5582) u C. volcanalis (R. Kriebel 5565) v C. brenesiana (R. Kriebel 3665) w C. centrosperma (R. Kriebel 5690) x C. cinnamomea (R. Kriebel 5330) y C. consimilis (R. Kriebel 5726) z C. dissitinervia (R. Kriebel 5317) A C. fraterna (R. Kriebel 5774) B C. friedmaniorum (R. Kriebel 5641) C C. galdamesiae (R. Kriebel 5736) D C. grayumii (R. Kriebel 5807) E C. hammelii (R. Kriebel 5737) F C. ombrophila (R. Kriebel 3120). G C. papillopetala (R. Kriebel 5718) H C. peltata (R. Kriebel 5658) I C. povedae (F. Oviedo 231) J C. schlimii (R. Kriebel 5614) K C. shattuckii (R. Kriebel 5681) L C. speciosa (R. Kriebel 5677) M C. subcrustulata (R. Kriebel s.n.) N C. subpeltata (R. Kriebel 3643) O C. trichosantha (R. Kriebel 5693) P C. xalapensis (R. Kriebel 5619).

White is the most common petal color found in Conostegia with a few species having pink to purple petals such as C. bigibbosa, C. cuatrecasii, and C. muriculata. In a few taxa like C. fragrantissima the white petals can have a red band at the base. Translucent petals can be found in different clades as well, and although it is tempting to think this might be related to floral size because several small-flowered taxa have them, some species with large petals have translucent petals as well (e.g. C. lasiopoda). Most species have glabrous petals but at least one has conspicuously papillose petals (C. papillopetala). Petal surfaces tend to be smooth in translucent petaled taxa and with rounded papillose cells in white-flowered species (Fig. 45). Although this difference in petal cells is evident also in micrographs (Fig. 46), intermediates exist and further study is needed to determine their possible systematic utility. In a few species, the petals persist after all other floral parts have fallen (of which C. pittieri might be the most notable example).

Figure 45. 

Longitudinal sections of petals in Conostegia. A Representative section of a species with translucent petals, Conostegia friedmaniorum B Representative section of a species with white petals, C. pittieri. Scale bar: 100 µm.

Figure 46. 

Scanning electron micrographs of Conostegia petal surfaces. A C. monteleagreana (R. Kriebel 5343) B C. brenesii (R. Kriebel 5631) C C. bernoulliana (R. Kriebel 5540) D C. montana (R. Kriebel 5496) E C. oerstediana (R. Kriebel 5338) F C. pittieri (R. Kriebel 5400) G C. rhodopetala (R. Kriebel 5542) H C. rufescens (R. Kriebel 5314) I C. hammelii (R. Kriebel 5317) J C. subpeltata (R. Kriebel 5347) K C. cinnamomea (R. Kriebel 5330) L C. dissitinervia (R. Kriebel 5377) M C. friedmaniorum (R. Kriebel 5641) N C. consimilis (R. Kriebel 5323) O C. schlimii (R. Kriebel 515). Scale bar: 100 µm.

The androecium in Conostegia consists of 8–52 isomorphic stamens. The basic arrangement of the stamens consists of five of them inserted opposite the sepals and five of them opposite the petals like most species in the Melastomataceae. Increase in the number of stamens are common, even predominant in sections Australis and Conostegia. These increases result in pleiostemony, and were the subject of a recent floral developmental study (Puglisi 2007; Wanntorp et al. 2011) which found two ways in which Conostegia species increase in stamen number: 1) by having a large stamen in alternipetalous position with small ones in antipetalous position; or 2) by a process called dedoublement where the stamens split in two (Puglisi 2007; Wanntorp et al. 2011). There appears to be no clear pattern indicating evolutionary relationships, with taxa with either of these developmental pathways being more closely related to another with the opposite pathway.

The posture of the stamens can go from erect, to forming a more or less a 45-degree angle between the filament and the anther (Fig. 47). Species with stamens that form an angle tend to have at least slightly bilaterally symmetric androecia. This condition is common in sections Australis and Conostegia as well as in the clade composed of C. osaensis, C. plumosa, C. speciosa, C. subcrustulata, and C. xalapensis within section Geniculatae. Bilateral symmetry in Conostegia appears also to be related to interactions between the stamen and style during development at least partly the result of the increase in number of stamens. Species in section Geniculatae, excluding the clade mentioned above, have stamens that cleanly surround the style and are radially symmetric, yet the flowers of these species might still have slight bilateral symmetry as a result of a gently curving style. In at least two species, C. fragrantissima and C. pittieri, the stamens are bent away and opposite the style.

Figure 47. 

Example of stamens of species in Conostegia to scale. a C. lasiopoda (R. Kriebel 5651) b C. monteleagreana (R. Kriebel 5747) c C. ortizae (D. Penneys 1857) d C. tenuifolia (R. Kriebel 5773) e C. bernoulliana (R. Kriebel 5540) f C. bigibbosa (R. Kriebel 5522) g C. bracteata (R. Kriebel 5816) h C. brenesii (R. Kriebel 5631) i C. cuatrecasii (R. Kriebel 5673) j C. fragrantissima (R. Kriebel 3174) k C. icosandra (R. Kriebel 5580) l C. montana (R. Kriebel 5544) m C. macrantha (R. Kriebel 5406) n C. oerstediana (R. Kriebel 5338) o C. pittieri (R. Kriebel 5400) p C. rhodopetala (R. Kriebel 5542) q C. rufescens (R. Kriebel 5627). r C. setosa (R. Kriebel 5731) s C superba (R. Kriebel 5582). t C. volcanalis (R. Kriebel 5565) u C. brenesiana (R. Kriebel 3665). v C. centrosperma (R. Kriebel 5690) w C. cinnamomea (R. Kriebel 5330) x C. consimilis (R. Kriebel 5726) y C. dissitinervia (R. Kriebel 5317) z C. fraterna (R. Kriebel 5774) A C. friedmaniorum (R. Kriebel 5641) B C. galdamesiae (R. Kriebel 5736) C C. grayumii (R. Kriebel 5807) D C. hammelii (R. Kriebel 5737) E C. ombrophila (R. Kriebel 3120). F C. papillopetala (R. Kriebel 5718) G C. peltata (R. Kriebel 5658) H C. povedae (F. Oviedo 231) I C. schlimii (R. Kriebel 5614) J C. shattuckii (R. Kriebel 5681) K C. speciosa (R. Kriebel 5677) L C. subcrustulata (R. Kriebel s.n.) M C. subpeltata (R. Kriebel 3643) N C. trichosantha (R. Kriebel 5693) O C. xalapensis (R. Kriebel 5619).

The filaments are mostly white to translucent. Sections Australis and Conostegia lack a clear geniculation towards the apex of the filament, whereas in section Geniculatae the geniculation is present in almost every species, except perhaps in C. fraterna (Figs 47–49). It is significant that the molecular phylogeny of Kriebel et al. (2015) placed species traditionally recognized in Conostegia such as C. plumosa, C. speciosa, C. subcrustulata and C. xalapensis in Geniculatae and that the latter three species which were studied from field-collected floral material have an evident filament geniculation. This morphological character thus supports their placement within section Geniculatae. It has to be considered that some variation does exist. For example, the micrograph of C. xalapensis (Fig. 49) does not show the evident geniculation very well whereas the photographs of the pickled stereoscope images of the same specimen do. In general, C. xalapensis shows an evident geniculation. Although most species which have filament geniculations present them towards the apex of the filament, in one species, C. brenesiana, the geniculation is in the middle of the filament.

Figure 48. 

Scanning electron micrographs of the side view of the stamens of Conostegia. A C. lasiopoda (R. Kriebel 5651) B C. lasiopoda close up of anther filament junction (R. Kriebel 5651) C C. tenuifolia (D. Santamaría 8863) D C. monteleagreana (R. Kriebel 5343) E C. ortizae (D. Penneys 1857) F C. brenesii (R. Kriebel 5631) G C. icosandra (R. Kriebel 5540) H C. macrantha (R. Kriebel 5406) I C. montana (R. Kriebel 5496) J C. montana close up of anther filament junction (R. Kriebel 5496) K C. oerstediana (R. Kriebel 5338) L C. pittieri (R. Kriebel 5400) M C. rhodopetala (R. Kriebel 5542) N C. rufescens (R. Kriebel 5314) O C. setosa (R. Kriebel s.n.) P C. hammelii (R. Kriebel 5317) Q C. subpeltata (R. Kriebel 5347) R C. trichosantha (R. Kriebel 5693) S C. cinnamomea (R. Kriebel 5330) T Close up of anther filament junction in C. cinnamomea (R. Kriebel 5330). Scale bar: 100 µm.

Figure 49. 

Scanning Electron Micrographs of the side view of the stamens of Conostegia. A C. speciosa (R. Kriebel 5489) B C. subcrustulata (R. Kriebel s.n.) C C. xalapensis (R. Kriebel 5555) D C. brenesiana (R. Kriebel 3665) E C. centrosperma (R. Kriebel 5690) F C. dissitinervia (R. Kriebel 5377) G C. friedmaniorum (R. Kriebel 5641) H C. consimilis (R. Kriebel 5323) I C. peltata (R. Kriebel 5658) J C. schlimii (R. Kriebel 515). Scale bar: 100 µm.

Anthers in Conostegia are almost exclusively yellow to sometimes orange (i.e. C. fragrantissima) with some taxa having hues of pink towards the apex in some populations (i.e. C. rufescens). In some species particularly in section Australis the anthers can be cream colored. Anthers in Conostegia lack evident staminal appendages with at the most, some species (e.i., C. bernoulliana) having an inconspicuous dorsal bump on the anther connective. The only structure that resembles an anther appendage in Conostegia is present in most species of section Australis. In these taxa, the anther base is briefly prolonged below the junction of the filament and anther thecae (Fig. 50). This character was recently documented in some species of Tococa (Michelangeli 2005) and Pachyanthus (Bécquer 2008). The documentation of this type of anther base in Conostegia is relevant because it had not been used before in the systematics of the group, and although lost in some species, helps to identify species in section Australis.

Figure 50. 

Scanning electron micrographs of the ventral and dorsal view of the stamens in Conostegia. A C. ortizae (D. Penneys 1857) B C. lasiopoda (R. Kriebel 5651) C C. monteleagreana (R. Kriebel 5343) D C. tenuifolia (D. Santamaria 8863) E C. brenesii (R. Kriebel 5631) F C. bernoulliana (R. Kriebel 5540) G C. montana (R. Kriebel 5496) H C. oerstediana (R. Kriebel 5338) I C. pittieri (R. Kriebel 5400) J C. rhodopetala (R. Kriebel 5542) K C. rufescens (R. Kriebel 5314) L C. hammelii (R. Kriebel 5317) M C. subpeltata (R. Kriebel 5347) N C. trichosantha (R. Kriebel 5693) O C. cinnamomea (R. Kriebel 5330) P C. subcrustulata (R. Kriebel s.n.). Scale bar: 100 µm.

Anther shape in Conostegia varies a lot even when considering only the species treated traditionally in the genus. This is in contrast to what has been previously stated in the literature. In their taxonomic studies of the Miconieae, Judd and Skean (1991) remarked that the non-appendaged anthers characteristic of Conostegia are ovoid, tapered to the apex, and open by a small apical pore. These anther characters lead to conclude that the genus did not evolve from within Miconia, since members of the latter genus show various modifications of either pore or connective structure. We now know that Conostegia is phylogenetically nested within the Miconieae, and furthermore that anthers of its species can be ovoid, oblong, linear, or variations on these shapes (Schnell 1996; Fig. 49). They are definitely not all ovoid. Also, they can be recurved or arcuate making them diffciult to describe. In addition, it is not very useful to say that a small pore characterizes the anthers of Conostegia. In fact, most species of Miconieae have small anther pores corresponding to their buzz pollinated syndrome, and for this reason this type of pore was coded as plesiomorphic by Judd and Skean (1991). Even if the size of the pore proves useful in the systematics of Conostegia, continuous measurements would have to be employed to determine their utility. The shape of the anther apices and anther pores is quite variable in Conostegia and merits further research. This will require careful placement of critically point dried anther apices on stubs and Scanning Electron Microscopy. Some of the variation seen in the pores has to do with the deeply channeled anthers in the ventral surface. In some taxa this deep channel reaches the pore area but in others it does not. Conostegia brenesiana stands out because of its very small anther thecae with broad pores which can resemble anthers in Miconia section Cremanium. In most species the pores are terminal to ventrally inclined. Dorsally inclined pores can be found in some species of section Geniculatae, and are especially evident in C. cinnamomea (Figs 50, 51).

Figure 51. 

Scanning Electron Micrographs of the ventral and dorsal view of the stamens in Conostegia. A C. xalapensis (R. Kriebel 5555) B C. brenesiana (R. Kriebel 3665) C C. dissitinervia (R. Kriebel 5377) D C. friedmaniorum (R. Kriebel 5641) E C. consimilis (R. Kriebel 5323) F C. papillopetala (R. Kriebel 5718) G C. peltata (R. Kriebel 5658) H C. schlimii (R. Kriebel 515). Scale bar: 100 µm.

With respect to the anatomy of the anthers, the sporangia in each anther theca were found to have two general arrangements. In species of section Australis and Conostegia they tend to be positioned side by side. On the contrary, in section Geniculatae they tend to be more-or-less superposed. All anthers were found to have druses. In some species such as Conostegia lasiopoda and C. oerstediana, the druses are present in the staminal connective, endothecium and anther septum (Fig. 52). In others, they are mostly restricted to the septum like in C. tenuifolia. Species in section Geniculatae tend to have druses on the proximal half of the outer side of the anthers (as in C. fraterna, C. friedmaniorum, C. ombrophila, and C. subcrustulata) (Fig. 52).

Figure 52. 

Anther anatomy in Conostegia. Each image is a transversal cut of an anther with a photograph under polarized light next to it. A–H are examples of anthers with sporangia positioned side by side. K–P are examples of anthers with sporangia superposed A–B C. lasiopoda (R. Kriebel 5651) C–D C. tenuifolia (D. Santamaría 8863) E–F C. oerstediana (R. Kriebel 5627) G–H C superba (R. Kriebel 5582) I–J C. subcrustulata (R. Kriebel 5653) K–L C. fraterna (R. Kriebel 5774) M–N C. friedmaniorum (R. Kriebel 5641) O–P C. ombrophila (R. Kriebel 3120). Scale bar: 100 µm.

Pollen of species in the Melastomataceae has been rarely documented in taxonomic treatments. This may be because the few studies that have been done have revealed little variation (reviewed in Renner 1993). For the species studied, Renner (1993) summarized the pollen as small, tricolporate, radially symmetrical, and isopolar; occasionally grains may have 4, 5 or more colpi, and some grains are dicolporate or heteropolar. Faint to distinct pseudocolpi (or subsidiary colpi, in the terminology of Patel et al. 1984) are usually present. The surface sculpture is smooth and striate to rugulate or rugulate-verrucate. Polyads and tetrads are known from Tococa spadiciflora and Miconia melanotricha (Patel et al. 1984). In the case of Conostegia, Roubik and Moreno (1991) provided the only images known to me of the anatomy of pollen of Conostegia species (including C. shattuckii as Miconia shattuckii). I have found that the pollen characteristics of Conostegia agree with Renner’s (1993) general description for the family; this is shown in micrographs provided for several species (Fig. 53).

Figure 53. 

Example of anther pores and pollen in Conostegia. A C. lasiopoda (R. Kriebel 5651) B C. ortizae (D. Penneys 1857) C C. tenuifolia (D. Santamaría 8863) D C. bernoulliana (R. Kriebel 5540) E C. brenesii (R. Kriebel 5631) F C. oerstediana (R. Kriebel 5338) G C. rhodopetala (R. Kriebel 5542) H C. rufescens (R. Kriebel 5314) I C. brenesiana (R. Kriebel 3665) J C. cinnamomea (R. Kriebel 5330) K C. consimilis (R. Kriebel 5323) L C. friedmaniorum (R. Kriebel 5641) M C. schlimii (R. Kriebel 515) N C. cinnamomea (R. Kriebel 5330) O C. hammelii (R. Kriebel 5317) P C. schlimii (R. Kriebel 515) Q C. subpeltata (R. Kriebel 5347) R C. macrantha (R. Kriebel 5406) S C. montana (R. Kriebel 5496) T C. oerstediana (R. Kriebel 5338). Scale bar: 100 µm (A–M); 10 µm (N–T).

The gynoecium can have from 4 to 25 carpels (Schnell 1996). Placentation is axillary as in most Melastomataceae (Renner 1993). The placenta in most Conostegia protrudes into the locule, either in laminar fashion with the ovules attached at the sides, or it is peltate with a clear stipe (Fig. 54). Intermediates are present, and in a few cases (e.g. C. xalapensis), the placenta looks like the peltate kind but lacks a clear stipe. Species of sections Australis and Conostegia have inferior ovaries, and in some species of section Conostegia the ovary can be elevated into an evident collar around the style base. Species in these two sections all have glabrous ovary apices. In contrast, species of section Geniculatae tend to have ovaries about two thirds inferior and several species have glandular-pubescent ovary apices. A collar around the style base is usually absent in section Geniculatae. Species of sections Australis and Conostegia have a glabrous torus whereas species in section Geniculatae can have a glabrous or glandular-puberulent torus. In one species, C. osaensis, the torus is beset with lepidote trichomes.

Figure 54. 

Example of placenta shapes in Conostegia. A C. lasiopoda (R. Kriebel 5651) B C. macrantha (R. Kriebel 5406) C C. schlimii (R. Kriebel 5614). Scale bar: 1 mm.

A significant discovery of this study is the deep blue stain recorded in anatomical sections inside the ovary of species in sections Australis and Conostegia (Fig. 36). On the other hand, this staining is absent in section Geniculatae. Staining with Ruthenium red has provided evidence that the substance in question is mucilaginous pectin, and field tests and photographs by Reinaldo Aguilar of with C. bernoulliana in the Osa Peninsula have demonstrated that the berries are sticky as would be expected from the presence of mucilage.

Conostegia can be said to have the highest diversity in style and stigma morphology in the whole Melastomataceae (Fig. 55). Most notable is the presence of crateriform lobed stigmas in several species (Figs 55, 56). These crateriform stigmas are unique to a subclade of Conostegia, although in some species the crater is reduced to almost absent but the lobes mostly remain present. Besides these obvious outliers, the diversity is still pronounced, ranging from short, stout, straight or apically hooked styles, to long, straight or gently curving styles. Stigmas can be punctiform, truncate, or variously enlarged (Fig. 55). Styles in Conostegia can be exserted or not. Biologically, this exertion corresponds to the maintenance of herkogamy (see Reproductive Biology section). Although the posture of the style appears to be taxonomically informative, this posture can vary through time within the same individual in some species. In species with exserted styles, two general trends are noticeable. The first trend, seen in species of section Australis as well as C. schlimii of section Geniculatae, is one in which the flower is either facing upward, or horizontally and thus the style is erect or horizontal. In both these similar postures, the style tends to surve gently towards the apex resulting in a more or less S shape. The other trend in species with exserted styles is almost the norm in species of section Geniculatae and involves deflexed styles. It should be noted that in this revision, exemplary flowers of all sections are presented in erect position for convenience (see Figs 40 through 43), but in the taxonomic treatment, images of live flowering plants display the natural posture of the flowers.

Figure 55. 

Example of styles of species in Conostegia to scale. a C. lasiopoda (R. Kriebel 5651) b C. monteleagreana (R. Kriebel 5747) c C. ortizae (D. Penneys 1857) d C. tenuifolia (R. Kriebel 5773) e C. balbisiana (G. Proctor 10285) f C. bernoulliana (R. Kriebel 5540) g C. bigibbosa (R. Kriebel 5522) h C. bracteata (R. Kriebel 5816) i C. brenesii (R. Kriebel 5631) j C. cuatrecasii (R. Kriebel 5673) k C. fragrantissima (R. Kriebel 3174) l C. icosandra (R. Kriebel 5580) m C. macrantha (R. Kriebel 5406) n C. montana (R. Kriebel 5544) o C. oerstediana (R. Kriebel 5338) p C. pittieri (R. Kriebel 5400) q C. rhodopetala (R. Kriebel 5542) r C. rufescens (R. Kriebel 5627) s C. setosa (R. Kriebel 5731) t C. superba (R. Kriebel 5582) u C. volcanalis (R. Kriebel 5565) v C. brenesiana (R. Kriebel 3665) w C. centrosperma (R. Kriebel 5690) x C. cinnamomea (R. Kriebel 5330) y C. consimilis (R. Kriebel 5726) z C. dissitinervia (R. Kriebel 5317) A C. fraterna (R. Kriebel 5774) B C. galdamesiae (R. Kriebel 5736) C C. hammelii (R. Kriebel 5737) D C. ombrophila (R. Kriebel 3120) E C. papillopetala (R. Kriebel 5718) F C. peltata (R. Kriebel 5658) G C. povedae (F. Oviedo 231) H C. schlimii (R. Kriebel 5614) I C. shattuckii (R. Kriebel 5681) J C. speciosa (R. Kriebel 5677) K C. subcrustulata (R. Kriebel s.n.) L C. subpeltata (R. Kriebel 3643) M C. trichosantha (R. Kriebel 5693) N C. xalapensis (R. Kriebel 5619).

Figure 56. 

Scanning electron micrographs of stigmas in Conostegia. A C. hammelii (R. Kriebel 5317) B C. subpeltata (R. Kriebel 5347) C C. trichosantha (R. Kriebel 5693) D C. cinnamomea (R. Kriebel 5330) E C. montana (R. Kriebel 5496) F C. oerstediana (R. Kriebel 5338) G Close up of a stigma lobe of C. oerstediana (R. Kriebel 5338) H C. pittieri (R. Kriebel 5400) I C. rufescens (R. Kriebel 5314) J C. speciosa (R. Kriebel 5489) K C. tenuifolia (D. Santamaría 8863) L C. xalapensis (R. Kriebel 5555) M C. brenesiana (R. Kriebel 3665) N C. dissitinervia (R. Kriebel 5377) O C. consimilis (R. Kriebel 5323) P C. schlimii (R. Kriebel 515). Scale: 100 µm.

There are two main clades where the style is not exserted beyond the stamens (not herkogamous). The first corresponds to section Conostegia and the other to the clade comprised of C. osaensis, C. plumosa, C. speciosa, C. subcrustulata, and C. xalapensis. Aside from the crateriform and or lobed stigma clade, which are derived from section Conostegia, all remaining taxa with a short style appear to have either a straight style or one that bends upward below the stigma. Within section Conostegia, style posture appears to change in most of its members, particularly in the crateriform or lobed stigma clade. The few observations of species in this group (Stratton 1989; Schnell 1996) suggest their flowers can last about two days. During this time the style bends downward usually blocking numerous stamens. Preliminary experiments (Kriebel unpublished data) show that if the style is removed, the stamens can unveil normally and that if the stamens are removed the style still bends (see photographs in section on Reproductive biology).

In the styles of the Conostegia clade, another outstanding aspect involves the presence of a stele within for their entire length (Figs 57, 58). Specifically, section Conostegia and convergently Conostegia ortizae in section Australis present this phenomenon. This stele is unknown in the rest of the Melastomataceae. Schnell (1996) was the first to document the stele in two species which are phenotypically divergent but belong to section Conostegia. This character is helpful to confirm the hypothesis, derived by optimizing morphological traits on the molecular phylogeny, that the calyptra and short style seen in the clade composed of C. osaensis, C. plumosa, C. speciosa, C. subcrustulata, and C. xalapensis must have evolved independently from the similar morphology seen in section Conostegia. No species including the ones just mentioned of section Geniculatae were found to have a vascular cylinder inside the style. These results also coincide with Schnell’s (1996) observations of a lack of a cylinder in C. subcrustulata. The stele found in the style of C. ortizae, in general, differs from those in species of section Conostegia because it has fewer vascular traces.

Figure 57. 

Two examples of longitudinal sections of flowers of Conostegia. Note the presence of a stele within the style in A Conostegia superba (R. Kriebel 5582) and the lack of a stele in B C. tenuifolia (D. Santamaría 8863). Scale bar: 1 mm.

Figure 58. 

Style transversal anatomy in Conostegia. A C. lasiopoda (R. Kriebel 5651) B C. tenuifolia (D. Santamaría 8863) C C. brenesii (R. Kriebel 5631) D C. pittieri (R. Kriebel 5543) E C. setosa (R. Kriebel 5731) F C. superba (R. Kriebel 5582) G C. friedmaniorum (R. Kriebel 5641) H C. hammelii (R. Kriebel 5317) I C. schlimii (R. Kriebel 515) J C. subcrustulata (R. Kriebel 5653) K C. trichosantha (R. Kriebel 5693) L C. xalapensis (R. Kriebel 5629). Scale bar: 100 µm.

Fruits of most species traditionally recognized as Conostegia have a truncate apex produced by the dehiscence or breaking of the calyptra. In addition, some have a prominent ovary apex that is retained in the berry and can be highly elevated in fruit (Fig. 59). Fruits of some species such as those of C. oerstediana have a pleasant taste.

Figure 59. 

Berries of some species of Conostegia. A C. lasiopoda (R. Kriebel 5651) B C. monteleagreana (R. Kriebel 5354) C C. polyandra (X. Cornejo 8126) D C. caelestis (R. Kriebel 5588) E C. cuatrecasii (R. Kriebel 5673) F C. icosandra (R. Kriebel 5580) G C. montana (R. Kriebel 5446) H C. oerstediana (R. Kriebel 5338) I C. rufescens (E. Saliceti s.n.) Photograph by E. Saliceti. J C. superba (R. Aguilar 12103) K C. subcrustulata (R. Kriebel 5333) L C. xalapensis (R. Kriebel s. n.) M C. ombrophila (R. Kriebel 5396) N C. pittieri (R. Kriebel 5757) O C. calocoma (R. Kriebel s. n.) P C. dissitiflora (R. Kriebel 5378) Q C. friedmaniorum (R. Kriebel 5497) R C. osaensis (R. Aguilar s. n.) S C. shattuckii (R. Kriebel 5688) T C. schlimii (R. Kriebel 5329). All photographs by the author except where specified.

Almost all species of Conostegia have small seeds averaging about 0.5 mm in length and varying in number from hundreds to thousands in a single berry. The most significant deviation from this pattern is observed in the clade comprised of C. osaensis, C. plumosa, C. speciosa, C. subcrustulata, and C. xalapensis, where seeds are fewer in number and average about double in length.

Seeds in Conostegia are mostly ovoid except for section Geniculatae where several species have pyramidal seeds (Figs 60–62) (Ocampo and Almeda 2013). In some cases like C. brenesiana most seeds are pyramidal but ovoid seeds can sometimes be found in the same fruit. Angles are absent except for some species in section Geniculatae that can be strongly angled. The lateral symmetrical plane is ovate in sections Australis and section Conostegia and frequently triangular in section Geniculatae. Tubercles on the seed surface are evident in in section Geniculatae and in C. monteleagreana of section Australis but are absent in section Conostegia.

The conclusion of this study is that despite the difficulty in coding seed characters, species of section Australis and section Conostegia have very similar seeds in being ovoid and smooth, whereas there is a lot of variation in seed morphology is in section Geniculatae, with ovoid to pyramidal seeds that frequently have angles and tubercle-like cells present just on the angles or covering the whole seed.

Figure 60. 

Seeds in Conostegia. A C. allenii (M. Nepokroeff 722) B C. hammelii (R. Kriebel 1420) C C. ombrophila (R. Kriebel 4887) D C. pittieri (D. Quiroz 800) E C. trichosantha (F. Almeda 6491) F C. cinnamomea (R. Hartman 12257) G C. brenesiana (R. Kriebel 4614) H C. dissitiflora (R. Kriebel 5378) I C. dissitinervia (R. Kriebel 5377) J C. peltata (R. Kriebel 5658) K C. grayumii (M. grayum 1834) L C. consimilis (A. Jiménez 2326) M C. oligocephala (R. Thorne 41087) N C. pendula (D. Santamaría 6672) O C. calocoma (R. Kriebel s.n.). Scale bar: 100 µm.

Figure 61. 

Seeds in Conostegia. A C. brenesii (A. Tonduz 12580) B C. caelestis (R. Kriebel 5617) C C. chiriquiensis (E. Alfaro 2365) D C. hirtella (A. Molia 3189) E C. icosandra (F. Ventura 20608) F C. macrantha (C. Schnell 1077) G C. micrantha (R. Kriebel 694) H C. montana (W. Stevens 25434) I C. centronioides (E. Little 6215) J C. extinctoria (H. David 1227) K C. ortizae (D. Penneys 1857) L C. lasiopoda (L. Fournier 303) M C. monteleagreana (F. Almeda 6075) N C. pittieri (C. Todzia 2045) O C. plumosa (P. Gentle 9258) P C. polyandra (P. Azevedo 6905). Scale bar: 100 µm.

Figure 62. 

Seeds in Conostegia. A C. procera (N. Britton 3607) B C. rhodopetala (C. Schnell 1081) C C. rufescens (O. Valverde 13) D C. setosa (D. Solano 1448) E C. speciosa (F. Almeda 2863) F C. subcrustulata (R. Kriebel 5333) G C. superba (J. Steyermark 47891) H C. tenuifolia (A. Rodríguez 11693) I C. volcanalis (E. Matuda 2644) J C. xalapensis (A. Soto 1772) K C. osaensis (R. Aguilar 12228) L C. papillopetala (R. Kriebel 5718) M C. ecuadorensis (S. Stern 328) N C. balbisiana (N. Britton 558) O C. bracteata (E. Killip 12158) P C. shattuckii (R. Kriebel 5688). Scale bar: 100 µm.