Eight new species of Cestrum (Solanaceae) from Mesoamerica

Abstract As part of the preparation of a taxonomic revision of Cestrum (Solanaceae) for Flora Mesoamericana eight hitherto undescribed species from Mexico, Guatemala, Costa Rica and Panama were identified. These eight new species are described and illustrated. Affinities of the species are discussed and Global Species Conservation Assessments presented.The new species are Cestrum amistadense A.K. Monro, sp. nov. (Vulnerable) which most closely resembles Cestrum longiflorum Ruiz & Pav., Cestrum contrerasianum A.K. Monro, sp. nov. (Vulnerable) which most closely resembles Cestrum formosum C.V.Morton, Cestrum darienense A.K. Monro, sp. nov. (Near Threatened) which most closely resembles Cestrum morae Hunz., Cestrum gilliae A.K. Monro, sp. nov. (Near Threatened) which most closely resembles Cestrum morae, Cestrum haberii A.K. Monro, sp. nov. (Vulnerable) which most closely resembles Cestrum poasanum Donn.Sm., Cestrum knappiae A.K. Monro, sp. nov. (Near Threatened) which most closely resembles Cestrum acuminatum Francey, Cestrum lentii A.K. Monro, sp. nov. (Near Threatened) which most closely resembles Cestrum johnniegentrianum D’Arcy and Cestrum talamancaense A.K. Monro (Least Concern) which most closely resembles Cestrum laxum Benth.


Introduction
Th e genus Cestrum (Solanaceae) includes ca. 150 species (Nee 1986(Nee , 2001Benítez and D'Arcy 1998) of moth, butterfl y and hummingbird pollinated small trees, shrubs, vines and robust herbs from the New World tropics and subtropics. Within the Solanaceae Cestrum is characterised by nearly actinomorphic fl owers, small, persistent calyces, longtubular corollas, small longitudinally dehiscent anthers held close to the corolla mouth, superior ovaries (Benítez and D'Arcy 1998) and few-seeded berries. Cestrum also frequently has truncated side branches subtended by a leaf at each node which can give the superfi cial appearance of an opposite arrangement of unequal leaves. Cytologically, Cestrum, together with its sister genus Sessea is unusual for the absence of typical angiosperm telomeres associated with chromosome ends (Sykorova et al. 2003). With respect to economic value, a number of species are cultivated for their brightly coloured fl owers and or fragrance (Beckett 1987) and many represent invasive or potentially invasive species within the tropics, especially on islands in the Pacifi c Ocean (Mauchamp 1997, Pattison et al. 1998, Space et al. 2003. Th e genus Cestrum was established by Linnaeus in 1753 (Linnaeus 1753) to accommodate material of two species, C. nocturnum L. and C. diurnum L. Complete revisions of Cestrum have since been undertaken by Dunal (1852) and Francey (1935Francey ( , 1936. Local treatments exist for the Antilles (Schulz 1909), Guatemala (Gentry and Standley 1974), Nicaragua (D'Arcy 2001), Costa Rica (Standley and Morton 1938), Panama (D'Arcy 1973), Venezuela (Benítez de Rojas and D'Arcy 1998) and Veracruz, Mexico (Nee 1986). As part of this author's preparation of a revisionary treatment for Flora Mesoamericana, eight currently undescribed species were discovered.
Th e taxonomy of Cestrum is complicated by a high proportion of synonyms and unidentifi ed collections. Nee (unpublished) encountered ca. 640 valid names for what he considered to be ca. 150 species. In addition, a relatively high proportion of collections in herbaria remain unidentifi ed to species. Of the 2147 collections examined as part of a taxonomic revision for Flora Mesoamericana, 1003 were identifi ed to species at the time of their accession and 266 were identifi ed subsequent to their incorporation, resulting in 737 (ca. 1/3) collections unidentifi ed to species prior to beginning the Flora Mesoamericana treatment.

Materials and methods
Two thousand one hundred and forty-seven collections of Cestrum from A, BM, F, G, GH, INB, LL, MO, NY, PMA, TEX and US (http://sweetgum.nybg.org/ih/) were examined. Material examined was assigned to ca. 60 morphospecies. Morphospecies were designated on the basis of a visual sort. Morphological characters used for this were the presence of 'minor' leaves associated with truncated side branches, leaf shape, texture and size, distribution, infl orescence disposition and size, bract size and shape, calyx and corolla morphology and fruit size, shape and colour. Morphospecies were then examined under a Willd M3C binocular microscope and Planapo lens at X64 to × 400 magnifi cation and a maximum of 117 morphological observations were made for each morphospecies. Th e morphological characters used included those established by Dunal, Francey and D'Arcy together with axillary bud colour, size and pubescence, position of the petiole, leaf length : width ratio, distribution of the infl orescences on the plant stem, organisation of the fl owers in the infl orescence and seed surface morphology. Pubescence was described in terms of hair division, gland association, orientation, shape, size and density. Hair division was classifi ed as simple versus branched and branched hairs were classifi ed as dendritic, stellate etc. Orientation was classifi ed as erect or appressed and shape as straight, curved or crooked. Hair density was somewhat problematic as observations were not taken per square cm but as visual appraisals made using a microscope. Pubescence was arbitrarily classifi ed as dense, sparse or moderate. Modifi ed leaves associated with the infl orescences are described as bracts or bracteoles. Bracts which subtend the pedicel are referred to as bracteoles; those which subtend other parts of the infl orescence are termed bracts.
Following the above detailed examination, the morphospecies were reduced to 47 in number. Th is reduced number of morphospecies were then associated with validly published names or determined to be undescribed species through a comparison with type material. Th is resulted in the following eight undescribed species being recognised from the 47 morphospecies.

Cestrum amistadense
Etymology. From the locality of the holotype, La Amistad Binational Park in Costa Rica and Panama.
Distribution. Premontane, montane, cloud and oak forest from 900 m to 2100 m. Collection notes indicate that this species is restricted to undisturbed or 'high' forest. Existing collection localities suggest that Cestrum amistadense is distributed over an area of ca. 7,360 km 2 of the Fila Costeña and the Talamanca Mountains in eastern Costa Rica and western Panama (Google Earth, accesssed April 21 2011, images from 2011).
Discussion. Of the six known collections of Cestrum amistadense, none had been previously determined to species. Comparison of the holotype and paratype material with type specimens from the herbaria listed in the Materials and Methods section recovered Cestrum amistadense as most similar to C. langeanum D'Arcy and C. longifl orum Ruiz & Pav. It can be distinguished from those species by the presence and distribution of pubescence, leaf surface, venation and infl orescence morphology as summarised in Tables 1 and 2. Conservation status. Using IUCN criteria (IUCN 2001) Cestrum amistadense is considered Vulnerable based on subcriteria B: Extent of Occurrence <20,000 km 2 (B1), a severely fragmented range and small number of collection localities (B1a) and continuing decline in the area of habitat due to the conversion of forest to agricultural land (B1b).
Distribution. Montane or cloud forest, often undisturbed forest. Existing collection localities suggest that Cestrum contrerasianum is distributed along the Pacifi c drainage of central Guatemala (Baja Verapaz, El Quiche, Huehuetenango) and southeastern Mexico (Chiapas) in an area encompassing ca. 13,400 km 2 (Google Earth, accessed 10 Dec 2010).
Discussion. Of the sixteen known collections of Cestrum contrerasianum, ten were previously determined as C. aurantiacum Lindl. Comparison of the holotype and paratype material with type specimens from the herbaria listed in the Materials and Methods section recovered C. contrerasianum as most similar to Cestrum formosum C.V.
Morton. It can be distinguished from those species on the basis of infl orescence number and morphology and fl ower and fruit morphology as summarised in Tables 3 and 4.
Conservation status. Using IUCN criteria (IUCN 2001) Cestrum contrerasianum is considered Vulnerable (VU B1ab(iii)) based on subcriteria B1 based on an Extent of occurrence <20,000 km 2 , a severely fragmented range and continuing decline in the area of habitat.
Etymology. Th is species is named after the Darien province, locality of the type and paratype collections.
Distribution. Cestrum darienense is known from two localities in Cerro Pirre and whilst none of the collection labels indicate a forest type, altitude information would suggest that this would be cloud forest. Cerro Pirre covers an area of ca. 50 × 25 km. Using collection label data and Google Earth (accesssed June 7, 2011; images from 2003) the Extent of Occurrence for this species is calculated to be ca. 280 km 2 .
Discussion. Of the three collections of Cestrum darienense seen, none had been previously determined to species prior to this study. A comparison of the holotype and paratype material with type specimens from the herbaria listed in the Materials and Methods section recovered Cestrum darienense as most similar to C. gilliae A.K. Monro and C. morae Hunz. Together with C. langeanum D'Arcy, C. darienense, C. gilliae and C. morae form a coherent morphological and geographical grouping within the genus of species from western Panama and the Chocó in Colombia and Ecuador characterised by broad, nearly three-veined leaves and determinate infl orescences. Cestrum darienense can be distinguished from C. morae and C. gilliae on the basis of stem, leaf, infl orescence and fl ower morphology as summarised in Tables 5 and 6. Th e Cerro Pirre mountain range has been noted as a locality for many endemic plant and animal species; this has been attributed to it being a moist forest refugium during dry periods of the Pleistocene (Haff er 1967).
Conservation status. Using IUCN criteria (IUCN 2001), Cestrum darienense is considered to be Near Th reatened. Th e Extent of Occurrence is calculated to be ca. 280 km 2 (Criteria B1 <5,000km 2 ) and there are only two known localities (Criteria B1a ≤5, Endangered). No decline in geographic range or fragmentation of the habitat has been observed, however, and Cerro Pirre is located within the Darién Biosphere Reserve, a UNESCO World Heritage Property. Th e Darién is vulnerable to factors which may result in future deforestation, e.g. economic development associated with the resolution of the armed confl ict in neighbouring Colombia and or an end to narco-traffi cking. Any associated decline in geographic range or fragmentation would result in this species being assessed as Endangered.
Distribution. Cestrum gilliae is known from three cloud forest localities within the Cerro Pirre mountain range. Cerro Pirre covers an area of ca. 50 × 25 km. Using collection label data and Google Earth (accesssed June 6, 2011; images from 2003) the Extent of Occurrence is calculated to be ca. 260 km 2 .
Discussion. Of the three collections of Cestrum gilliae seen, only one had been previously determined to species, as C. langeanum D'Arcy. A comparison of the holotype and paratype material with type specimens from the herbaria listed in the Materials and Methods section recovered C. gilliae most similar to C. morae Hunz. and to a lesser extent C. langeanum D'Arcy (see Discussion for C. darienense above). For this reason Cestrum gilliae is contrasted to both C. morae and C. langeanum on the basis of habit and infl orescence and fl ower morphology as summarised in Tables 7 and 8 respectively.
Etymology. Th is species is named after Sandra Knapp (1956-), Anglo-US botanist and Solanaceae specialist who collected the holotype and three of the paratype collections.
Distribution. Tropical wet, premontane and montane forest from 1100 to 1600 m. Collection notes indicate that this species is known from primary or undisturbed forest. Existing collection localities suggest that Cestrum knappiae is restricted to an area of the Main Divide (river drainage between the Caribbean Sea and Atlantic Ocean) of the Talamanca Mountains ca. 270 km in extent that runs from Parque Nacional Tapantí in W in Costa Rica to the Fortuna Forest Reserve and Palo Seco Protected Areas in the E in Panama. Th e Extent of Occurrence is calculated to be 5,400 km 2 (Google Earth, accesssed June 2 2011, images 2001 to 2006).
Discussion. Seven of the 15 collections of Cestrum knappiae examined had been previously determined as Cestrum fragile Francey. A comparison of the holotype and paratype material with type specimens from the herbaria listed in the Materials and Methods section recovered Cestrum knappiae as most similar to C. acuminatum D'Arcy, C. fragile and C. cristinae D.A.Soto. It can be distinguished from those species based on size, leaf, fl ower and fruit morphology as summarised in Tables 11, 12 and 13. Conservation status. Using IUCN criteria (IUCN 2001) Cestrum knappiae is considered Near Th reatened (NT). C. knappiae meets criterion B1 (Extent of Occurrence <20,000 km 2 ) and one subcriterion, a (number of localities <10). Th e full extent of the species' Extent of Occurrence, however, is located within protected areas. Th ere is considerable pressure for copper and gold mining within Costa Rica and Panama within the Extent of Occurrence which may present a threat of fragmentation or decline in the near to medium term future. If mining were to take place within this area then it is likely that C. knappiae would be classifi ed as Vulnerable.
Etymology. Th is species is named after the US collector of the holotype Roy Lent (1931-), who worked for F in Costa Rica.
Distribution. Wet premontane forest from 1100 to 1700 m on Pacifi c and Caribbean drainage of the Talamanca Mountains, Costa Rica and Panama. Cestrum lentii is known from two localities ca. 210 km apart at the eastern (La Fortuna, Chiriquí, Panama) and western (Tapantí, Cartago, Costa Rica) ends of the Talamanca Mountains. It is likely that populations of C. lentii connect these localities and that the absence of records is a refl ection of sampling eff ort. Assuming that C. lentii is found throughout the Talamanca Mountains between altitudes of 1100 to 1700 m then an estimated Area of Occupancy for this species is 5,880 km 2 (Google Earth, accessed June 17, 2011, images 2001, 2006, 2009.
Discussion. None of the four known collection of this species had been determined to species prior to this study. A comparison of the holotype and paratype material with type specimens from the herbaria listed in the Materials and Methods section recovered C. lentii as most similar to C. johnniegentrianum D'Arcy. It can be easily distinguished from this species based on leaf and infl orescence morphology as summarised in Table 14.
Etymology. From the Talamanca mountains, the locality of all known collections of this species.
Distribution. Cestrum talamancaense is known from three locations which span the entire range of the Talamanca Mountains from Chirripó, Costa Rica in the west to La Fortuna, Panama in the east. Th e altitude range for this species is believed to be 2000-3200 m. Th is and collection label data suggest that C. talamancaense is restricted to oak forest and subparamo vegetation. Given the small number of collections this should be considered provisional. Using this altitude range and the location of the three known localities the Area of Occupancy is calculated to be 2,300 km 2 (Google Earth, accessed June 20, images from 2003,2004,2006).
Discussion. Of the four collections of Cestrum talamancaense seen none had previously been identifi ed to species. A comparison of the holotype and paratype material with type specimens from the herbaria listed in the Materials and Methods section recovered C. talamancaense as most similar to C. laxum Benth. and C. irazuense Kuntze. Cestrum laxum and C. irazuense occupy a similar altitudinal range. Cestrum irazuense occupies an overlapping but broader geographical range whilst C. laxum has a distinct and much broader geographical range being known from Mexico, Guatemala, El Salvador and Honduras. Th e species can be distinguished based on axillary bud, petiole and fl ower morphology as summarised in Tables 15 and 16.
Conservation status. Using IUCN criteria (IUCN 2001) Cestrum talamancaense is considered Least Concern. C. talamancaense has an Area of Occupancy of 2,300 km 2 (Criteria B2, >2000 km 2 ) and meets a single subcriteria for criteria Ba (number of localities less than 5). In addition the whole of the range of this species is currently not fragmented and within protected areas both in Costa Rica and Panama. Should current attempts at illicit mining within the Area of Occupancy persist, however, the threat status may need to be revised to Near Th reatened. Paratypes