Taxonomic revision of Martinella Baill. (Bignonieae, Bignoniaceae)

Abstract Martinella Baill. is a genus of Neotropical lianas in tribe Bignonieae (Bignoniaceae). The genus is monophyletic and well supported by morphological and molecular characters. Members of Martinella are characterized by a continuous interpetiolar ridge surrounding the stem, bilobed or 4–5-parted calyces, and minute triangular prophylls of the axillary buds. Generic circumscription remained unchanged since the description of the genus, although unclear species limits remained. Based on extensive fieldwork, herbarium work, and a molecular phylogenetic hypothesis for the genus, we here recognize five species of Martinella. Of these, three were recognized in earlier treatments for the genus, while two represent new species described here, Martinella lanuginosa Kataoka & L.G.Lohmann, sp. nov. and Martinella tomentosa Kataoka & L.G.Lohmann, sp. nov.Martinella iquitoensis A.Samp. is treated as a synonym of M. insculpta Sprague & Sandwith. In addition, one second-step lectotype is designated for Bignonia martini DC., and neotypes are designated for Doxantha longisiliqua Miers and Martinella gollmeri K.Schum. This work provides a full taxonomic treatment for Martinella, including a complete list of synonyms, morphological descriptions, illustrations, photographs, distribution maps, conservation status, and comments for all five species recognized.


Introduction
Martinella Baill. (Bignonieae, Bignoniaceae) is a genus of Neotropical lianas, whose monophyly is supported by molecular phylogenetic studies (Lohmann 2006) and by morphological features. Namely, minute triangular prophylls of the axillary buds and interpetiolar ridges surrounding the stems are thought to represent morphological synapomorphies of the genus (Lohmann and Taylor 2014). Additionally, silvery or whitish leaflets on the abaxial surface, bilobed or 4-5-parted calyces, and corollas with a constricted basal portion and an upper campanulate portion also characterize species of Martinella.
Baillon (1888) described Martinella based on reproductive characters such as the irregularly 2-4-lobed calyces, bilabiate corollas with a wide tube (presumably referring to what was named Martinella-type flower nearly a century later; see , stipitate ovary that sits on a large nectariferous disk, and glabrous, flattened and narrow fruits. The genus was described based on Bignonia martini DC. [= Martinella obovata (Kunth) Bureau & K.Schum.], and the new combination Martinella martini (DC.) Baill. was proposed. Schumann (1894) described the new species, Martinella gollmeri K.Schum. [= Martinella obovata] based on the shallow and bowl-shaped nectariferous disk and frizzy calyces. Two years later, Bureau and Schumann (1896) transferred Spathodea obovata Kunth into Martinella, proposing the new combination Martinella obovata (Kunth) Bureau & K.Schum., which became the accepted name for Martinella martini. Sprague and Sandwith (1934) described Martinella insculpta Sprague & Sandwith, while Sampaio (1935) described M. iquitoensis A.Samp. and M. manaosiana A.Samp. (Sampaio 1936); both of these names are synonyms of M. insculpta. More recently, Zuntini and Lohmann (2014)  The circumscription of Martinella remained very stable over the years (Lohmann and Taylor 2014). Despite the generic stability, delimitation of the Amazonian species remained confusing, which led some authors to consider the Amazonian Martinella as part of a species complex due to overlapping morphological characters (e.g., MacBride 1961, Zuntini and. Alwyn Gentry treated M. insculpta as a synonym of M. obovata in the floristic treatments of several Neotropical countries such as Panama (Gentry 1973), Ecuador (Gentry 1977), and Venezuela (Gentry 1982).
In the most recent synopsis of the genus (Zuntini and Lohmann 2014), three species were recognized: M. insignis, M. iquitoensis [= M. insculpta], and M. obovata. A recent molecular phylogeny of Martinella (Kataoka and Lohmann in prep.) recovered five main clades that are easily diagnosed by morphological features. Each of these clades is here recognized as a distinct species. Of these, three correspond to species treated in the recent synopsis of the genus (Zuntini and Lohmann 2014), i.e., Martinella insculpta, Martinella insignis, and Martinella obovata, while two correspond to taxa that are newly described here, i.e., Martinella lanuginosa Kataoka & L.G.Lohmann and Martinella tomentosa Kataoka & L.G.Lohmann.

Methods
The taxonomic revision of Martinella was based on living specimens and observations made on fresh material during field expeditions and the analyses of herbarium specimens deposited in the following herbaria: IAN, INPA, MG, MO, NY, QCA, QCNE, R, RB, SPF, and UFACPZ (acronyms follow Thiers, continuously updated). All specimens were examined either physically or digitally through high quality photographs of herbarium specimens. In many cases we accessed specimens' photographs that were available in virtual herbaria via the JSTOR Global Plants (https://plants.jstor.org/), the Reflora Virtual Herbarium (http://reflora.jbrj.gov.br/reflora/herbarioVirtual/), or websites of individual herbaria.
Field expeditions were conducted between June and December 2016 in the Brazilian states of Acre, Amazonas, Mato Grosso, Pará, and Roraima. All specimens were deposited at SPF. All accepted names are listed in alphabetical order. Nomenclatural discussions follow the International Code of Nomenclature for algae, fungi, and plants (Shenzhen Code) (Turland et al. 2018). Citations of type specimens are followed by the herbarium acronym and barcode, unless otherwise stated between brackets.
We used a molecular phylogeny (Kataoka and Lohmann in prep.) and morphological data to circumscribe species. We treated separately evolving lineages as species, following De Queiroz (2007). In addition, only taxa diagnosable by unique combinations of morphological features were recognized as species (Cracraft 1983). Therefore, we recognized species as separately evolving lineages that share a unique combination of morphological characters.
Morphological descriptions follow the general terminology of Lohmann and Taylor (2014). Additional terms follow Radford et al. (1974) for general morphology, Hickey (1973) for leaf shape and venation, Weberling (1992) for inflorescence type, Nogueira et al. (2013) for trichome type, and Gentry and Tomb (1979) or Halbritter et al. (2018) for pollen morphology. All measurements were carried out on dried specimens and/or rehydrated material. In addition, pollen from herbarium specimens were analyzed using scanning electron microscopy (SEM) on a Zeiss DSM 970 scanning electron microscope. Rare character conditions are shown in parentheses in the species descriptions.
Distributions maps were produced in QGIS 2.18 (QGIS Development Team 2018) using a dataset that included a combination of two separate datasets: (i) a newly generated distribution dataset with approximately 150 records from collections made in the field and from digitized specimen labels, and (ii) a dataset with approximately 500 records compiled during the past 25 years (Lohmann unpublished data, described in Meyer et al. 2017).
Preliminary conservation status assessments were performed using the complete distribution dataset using the Geospatial Conservation Assessment Tool (GeoCAT; http:// geocat.kew.org/) (Bachman et al. 2011). This tool considers the metrics Extent of Occurrence (EOO) and Area of Occupancy (AOO) for 4 km 2 grids to objectively estimate conservation status based on the IUCN's criterion B (IUCN 2012; IUCN Standards and Petitions Subcommittee 2017). We only considered EOO to estimate conservation status of each species as this criterion is less prone to extinction risk overestimation.
The list of examined specimens was produced using the R package monographaR (Reginato 2016).

Geographic distribution
Members of Martinella are distributed in wet forests of Central America, northern South America, the Amazon and the Atlantic Forest of Brazil, between 0-1700 m above sea level (a.s.l.) (Zuntini and Lohmann 2014). Among the five Martinella species recognized in this study, M. obovata is the most frequent and broadly distributed, occurring from southern Mexico to the southern Amazon, reaching as far south as Bolivia and the Brazilian state of Mato Grosso do Sul. Martinella insculpta is also broadly distributed in Central America and Amazonia, but is less common when compared to the sympatric M. obovata. The other three species in the genus are rare, with narrow distribution ranges. The only known records of M. tomentosa are from Central Brazilian Amazon (Amazonas state), while M. lanuginosa is only known from western Brazil (Acre state), Peru, and northern Colombia. Lastly, M. insignis is the only member of Martinella that is restricted to the Atlantic Forest, occurring in the states of Espírito Santo and Bahia, in eastern Brazil.

Habitat
Species of Martinella occur in wet Neotropical forests. Martinella insculpta, M. lanuginosa, and M. tomentosa predominantly occur in terra firme (non-flooded) forests in the Amazon, with some reports of M. insculpta growing in white-sand soils. Martinella obovata preferentially occurs along riverbanks of the Amazonian white-water rivers, where many individuals were found during field expeditions, and where many collections were made over the years. Martinella insignis is restricted to sandy soils of the Brazilian Atlantic Forest, growing close to the shore (Zuntini and Lohmann 2014).

Reproductive biology
All species of Martinella share the flower morphology described by  as Martinella-type flower. This floral morphology is characterized by spathaceous, tubular or urceolate calyces, and by tubular, infundibuliform, or urceolate corollas that are straight and coriaceous, varying in color from red to magenta, or white Alcantara and Lohmann 2010). These traits suggest hummingbird pollination.
All Amazonian species of Martinella fit the pollination syndrome suggested by their floral morphology, which is supported by field observations, although Euglossini bee visitation was also observed . Conversely, M. insignis has a yellow corolla that is unique in the genus. This corolla color suggests bee pollination, although field studies are needed to confirm this prediction.

Economic and ethnobotanical uses
Bignoniaceae species are traditionally used for timber, handicraft, and medication (Gentry 1992). Martinella species are broadly used by Amazonian indigenous peoples to treat eye inflammation and conjunctivitis (e.g., Gentry and Cook 1984;Alexiades 1999). Extracts are made using the root's outer bark, which is scraped, macerated with water, filtered and used as eye drops (e.g., Gentry and Cook 1984; similar reports are available in herbarium specimens' labels, e.g., G.T. Prance 15557 deposited at INPA and Lewis 14026 deposited at QCNE).
The widespread use of Martinella extracts for medicinal purposes throughout the Amazon motivated chemical analyses, which led to the discovery of the alkaloids Martinelline and Martinellic acid from organic extracts of M. iquitoensis [= M. insculpta] (Witherup et al. 1995). Further studies have been conducted attempting to synthesize these compounds (e.g., Davies et al. 2013).

Cytology
Chromosome counts for Martinella obovata is 2n = 40 (Goldblatt and Gentry 1979), which also corresponds to the most common chromosome number in the tribe Bignonieae as a whole (Cordeiro et al. 2017).

Morphology
Habit. All species of Martinella are lianas, although seedlings are self-supporting shrubs up to 70 cm tall (see Fig. 1A-C).
Stems. Mature stems of Martinella bear lenticels and solid pith with four phloem wedges in cross section. Stems with four phloem wedges predominate within tribe Bignonieae and are also found in Adenocalymma, Callichlamys, Cuspidaria, Fridericia, Lundia, Manaosella, Neojobertia, Tanaecium, Tynanthus, Pachyptera, Pleonotoma, andStizophyllum (Lohmann 2006, Lohmann andTaylor 2014). Young stems are cylindrical and generally remain cylindrical at maturity, becoming tetragonal in Martinella insculpta. A continuous ring surrounds the interpetiolar regions of stems (see Fig. 1E). The stem surface is smooth, sparsely to densely covered with trichomes. Stems over ca. 4 cm in diameter often have sparse lenticels. Non-lenticelled parts of the stem are pale to dark green, often with dark blotches.
Prophylls of the axillary buds. Structures traditionally referred to as pseudostipules (Gentry 1980) were subsequently shown to represent well-developed prophylls of the axillary buds (Lohmann and Taylor 2014). Prophylls are very useful structures for the identification of genera and species in tribe Bignonieae, often representing morphological synapomorphies of generic-level clades (Lohmann and Taylor 2014). All species of Martinella have minute triangular prophylls, a putative morphological synapomorphy of the genus (Lohmann 2006) (see Fig. 1E, H).
Leaves. In Bignonieae, leaves are commonly 2-foliolate or 3-foliolate with the terminal leaflet modified in a tendril (Gentry 1980;Lohmann and Taylor 2014). In mature individuals of Martinella, leaves are exclusively 2-foliolate, bearing a trifid tendril, with discolor leaflets that bear glandular trichomes on the abaxial side (see Fig. 1C, D, F, G). Young individuals of M. insculpta and M. obovata show unifoliolate leaves at first and lack tendrils (see Fig. 1A, B). In some taxonomic treatments, Martinella was described as bearing simple or trifid tendrils (MacBride 1961;Gentry 1977;Zuntini and Lohmann 2014). However, careful examination of herbarium specimens revealed that most seemingly simple tendrils corresponded to trifid tendrils with missing parts. Trifid tendrils represent the ancestral character state within tribe Bignonieae and were maintained in Martinella (Sousa-Baena et al. 2014). Leaf venation is brochidodromous in all species of Martinella. Leaf domatia is only found in M. insignis, as pocket-like structures at the axil of the midvein with the secondary veins, on the abaxial side of leaflets, mainly at the basal portion.
Trichomes. Four main types of trichomes are found in tribe Bignonieae: (i) nonglandular (eglandular) trichomes, (ii) peltate glandular trichomes, (iii) stipitate glandular trichomes, and (iv) patelliform/cupular glandular trichomes (Nogueira et al. 2013). Trichome distribution on the plant body is highly variable, although some genera of tribe Bignonieae are readily recognized by diagnostic patterns of trichome distribution, e.g., Adenocalymma, with patelliform glandular trichomes on the prophylls of the axillary buds, floral bracts, calyces, bracteoles, and fruits (Lohmann and Taylor 2014;Fonseca and Lohmann in prep.), and Pachyptera, with a field of patelliform glandular trichomes at the interpetiolar region and petiole apex (Francisco and Lohmann 2018). In species of Martinella, three trichome types are found: (i) non-glandular trichomes (referred to as simple eglandular trichome hereafter), (ii) stipitate glandular trichomes, and (iii) patelliform glandular trichomes (commonly referred to as "glands" in the literature). The simple eglandular trichomes are distributed throughout the plant, often with density variation in different plant organs; stipitate glandular trichomes are found in high density on the whole plant of M. insignis and M. lanuginosa and in variable density at different parts of the plant in other species; patelliform glandular trichomes are found on the whole plant of all members of Martinella, mainly at the interpetiolar region, and at the base of the abaxial surface of leaflets (see Fig. 1E, H). The patelliform glandular trichomes can also be found on stems, inflorescences, and calyces of M. insculpta and M. obovata.
Inflorescences. Flowers of Martinella are organized in axillary and/or terminal inflorescences that bear six to 26 flowers, although only a few flowers open at a time. Botryoid inflorescences are found in M. insculpta, racemes are found in M. obovata, and thyrses are found in M. insignis, M. tomentosa, and M. lanuginosa. Botryoid and racemose inflorescences (see Fig. 2A, B) are lax, contrasting with the congested thyrses, which show higher levels of branching and a higher number of flowers per inflorescence. Calyx. Calyx morphology is highly variable within Bignonieae (Lohmann and Taylor 2014). However, this trait is quite constant within Martinella, with the tubular-campanulate and irregularly 2-4-lobed calyx (or regularly 5-lobed in M. insignis) representing a diagnostic character (Lohmann 2006;Lohmann and Taylor 2014) (see Fig. 2B-D).
Corolla. Corolla shape is an additional distinctive feature in Martinella. All species show tubular-campanulate corollas, with a tubular basal portion that is long and much narrower than the markedly campanulate upper portion, giving an inflated appearance compared to the basal portion (see Fig. 2A-D). This distinctive corolla morphology was described by Gentry as the Martinella-type flower . Corolla color varies from pale lilac (M. obovata) to dark magenta (M. insculpta) or yellow (M. insignis). Corolla color in Martinella lanuginosa and Martinella tomentosa is unknown, but seems to vary from lilac to magenta, as in other Amazonian species.
Androecium. Members of Martinella have four didynamous stamens and one very reduced staminode (ca. 1 mm long). The stamens are inserted at the inferior portion of the corolla tube, at approximately 1/4 of the corolla length. Anthers are included, bearing straight and divaricate thecae, and showing glabrous filaments and thecae.
Pollen. Gentry and Tomb (1979) highlighted the usefulness of pollen morphology to generic-level identification of members of Bignonieae, although this trait shows convergent evolution. In Martinella, pollen is quite constant, tricolpate with reticulate exine (see Fig. 2E) in all species. Similarly, reticulate pollen grains are also found in Bignonia, Mansoa, Pachyptera, and Pyrostegia Tomb 1979, Francisco andLohmann 2018).
Gynoecium. As in most Bignonieae, Martinella has a bilocular ovary with two fused carpels with axillary placentation (Gentry 1980), a single style with lanceolate and bilamellate stigma. The ovary is terete, with a glabrous and smooth surface.
Fruits. Species of Martinella have linear, flattened, septicidal capsules with two valves. Capsules of Martinella are among the longest fruits in Bignonieae, reaching up to 1.5 m long and 3 cm wide (Fig. 2G), only comparable to Dolichandra fruits (Fonseca et al. 2017). In addition, the capsules are glabrous to puberulent.
Seeds. Seeds of Martinella are symmetrically winged, oblong, and thin (Fig. 2F). The seed body is chartaceous, opaque and brown or green, even when dried (in M. obovata). The seed wings are membranous and translucent, brown or green-colored. Like several other clades of Bignoniaceae, seeds are wind-dispersed (Gentry 1979;Gentry 1980).
Discussion. The nomenclatural type of Martinella has been indicated as Martinella martinii (DC.) Baill. ex K.Schum. in earlier treatments of the genus (e.g., Lohmann and Taylor 2014; Zuntini and Lohmann 2014) because Schumann (1894) was the first to explicitly associate the genus name with a species epithet. However, Baillon (1888) provided a footnote that says "Generis typus est Bignonia Martini DC.," representing a valid reference to a previously published basionym, and validly publishing the name Martinella martini (DC.) Baill. (see Art. 41.3 and 38.13 of Turland et al. 2018).

Key to species of Martinella
Distribution and habitat. Martinella insculpta is widely distributed through Amazonian terra firme forests and Central American wet forests (Fig. 4). This species occurs from 59-650 m a.s.l.
Etymology. The specific epithet means carved, engraved, referring to the aspect of leaflet venation on both sides, but especially on the adaxial surface.
Phenology. Flowering specimens were collected from February to November, while fruiting specimens were collected from August to December.
Conservation status. Least Concern (LC) based on the EOO of 4,002,910 km 2 . Discussion. Here we synonymize Martinella iquitoensis under Martinella insculpta. Gentry (1973) synonymized Martinella insculpta A.Samp. under M. obovata, a circum-  scription that was followed in subsequent taxonomic studies (e.g., Gentry 1977;Gentry 1982). However, the analysis of a large number of living and herbarium specimens of these taxa indicated that the original description and type specimen of M. insculpta actually match the circumscription of M. iquitoensis. Therefore, M. iquitoensis A.Samp. (published in 1935), is here treated as a synonym of Martinella insculpta Sprague & Sandwith (published in 1934).

Martinella insignis
Distribution and habitat. Martinella insignis is endemic to the Atlantic Forest of Eastern Brazil (see Fig. 6), where it grows in sandy soils, in areas between 62-590 m a.s.l.
Etymology. The specific epithet means conspicuous, readily distinguishable, referring to the contrasting corolla color when compared to other species.
Phenology. Flowering specimens were collected between October and February, while fruiting specimens were collected in January and November.
Conservation status. Vulnerable (VU) based on the EOO of 12,721 km 2 . Discussion. Martinella insignis is the only representative of the genus that occurs in the Atlantic Forest, where it is rare, with only a few herbarium collections available to date. In addition, M. insignis is remarkably distinctive from its congeneric species due to the membranous leaflets with pocket-shaped domatia on the abaxial surface, 5-lobed and aristate calyces, and yellow corollas. Diagnosis. Martinella lanuginosa differs from other Amazonian species of Martinella by the lanuginose leaflets on the abaxial surface and inflorescences arranged in lax thyrses, contrasting with the glabrous or tomentose leaflets on the abaxial surface and inflorescences botryoid or racemose found in all other Amazonian species.
The widespread M. obovata recognized here includes multiple synonyms, several of which required the designation of lectotypes or neotypes. During Alwyn Gentry's prolific career, he published many taxonomic treatments and Floras in which he listed several types and unintentionally designated lectotypes. For example, Gentry (1973) unintentionally designated lectotypes for Bignonia fockeana Miq. and Tabebuia cordata Benth. The specimens designated as lectotypes are in good condition, allowing for an accurate identification of these taxa, representing good lectotypes. Some of Gentry's unintentional lectotypes were first-step lectotypifications (see Art. 9.17 of Turland et al. 2018), requiring second-step lectotypes. When appropriate, the required second-step lectotypes are proposed here. For example, in the protologue of Bignonia martini, De Candolle (1845) specifically cited a specimen collected by Martin in Cayenne (French Guiana). Gentry (1973) cited as "type" collections made by J. Martin in French Guiana deposited at U and US. We found additional collections made by J. Martin in Cayenne that were annotated as "Type" and "Isotype" deposited at P. One of those specimens bears flowers, is in good condition and has a stamp that indicates "Type". This material is here selected as a second-step lectotype. Duplicates (isolectotypes) of the type collection are deposited at P, U and US.
Bignonia longisiliqua Bertero ex Spreng. (Sprengel 1825) and Bignonia longisiliqua Vell. (Vellozo 1825(Vellozo [1829) are illegitimate homonyms of Bignonia longisiliqua Jacq. (Jacquin 1780). While B. longisiliqua Bertero ex Spreng. is a synonym of M. obovata, Bignonia longisiliqua Vell. is a synonym of Catalpa longissima (Jacq.) Dum. Cours., and Bignonia longisiliqua Jacq. is a synonym of Stizophyllum perforatum (Cham.) Miers. Bignonia longisiliqua Bertero ex Spreng. was described based on a specimen from "Ad fl. Magdalen." (Magdalena river, Colombia) collected by C.L.G. Bertero. However, the referred specimen was never mentioned in subsequent taxonomic studies and could not be located. Instead, a specimen collected by C.L.G. Bertero in Santa Martha (Colombia) was cited by De Candolle (1845). Doxantha longisiliqua Miers is a new name subsequently published based on a specimen from "Sa. Martha" (Colombia), also collected by C.L.G. Bertero, with explicit reference to the specimen cited in De Candolle (1845). We found two specimens collected by Bertero in Santa Martha, one deposited at G-DC and the other deposited at MO. These specimens were identified as types of Bignonia longisiliqua Bertero ex Spreng., with the specimen at MO (barcode  including a "Type Specimen" stamp. However, we did not find any publication citing the MO specimen as a nomenclatural type. In addition, it is likely that the specimen from Magdalena river that Sprengel used to describe B. longisiliqua was destroyed at B, where many specimens were held after 1890, including some of those collected by Bertero (Stafleu and Cowan 1976). Therefore, we designate the well-preserved specimen deposited at G-DC as a neotype for Bignonia longisiliqua Bertero ex Spreng. Lastly, the collection year written on the label "1822" is likely wrong because C.L.G. Bertero's travels in the West Indies were from 1816-1821 (Stafleu and Cowan 1976). Given this information, we could not confidently assign the MO specimen as a duplicate (isoneotype).
In the original description of Martinella gollmeri, a specimen collected in Venezuela by J. Gollmer is cited. This specimen was most likely destroyed at B; no isotypes or illustrations have been found, and a neotype from Venezuela that matches the original description is here designated as a neotype.
The holotype of Arrabidaea duckei A.Samp. is interpreted to be mounted in two sheets, as both sheets have the same accession number (24094)  Diagnosis. Martinella tomentosa differs from other Amazonian species of Martinella by the tomentose leaflets and branches, and inflorescences arranged in thyrses, as opposed to the glabrous to lanuginose leaflets and inflorescences arranged in racemes or lax thyrses of all other Amazonian species.
Distribution and habitat. Martinella tomentosa is restricted to the central portion of Amazonia (Fig. 12), where it occurs in Terra Firme forests from Brazil (state of Manaus).  Etymology. The species epithet relates to the distinguished tomentose indumentum in leaves and branches of M. tomentosa.
Phenology. Flowering specimens were collected in June. Conservation status. Data deficient (DD); known from only three specimens of two localities.
Discussion. Martinella tomentosa is a new species whose description is strongly supported by morphological and molecular phylogenetic data (Kataoka and Lohmann in prep). The tomentose leaves and branches are the most striking characteristics that easily distinguish M. tomentosa from all other species of Amazonian Martinella. This new taxon is only known from very few collections from Central Amazonia, none of which was collected during the fruiting season.