Lonchophylla chocoana, DÁVALOS, 2004

DÁVALOS, LILIANA M., 2004, A New Chocoan Species of Lonchophylla (Chiroptera: Phyllostomidae), American Museum Novitates 3426, pp. 1-16 : 4-9

Lonchophylla chocoana , new species

Figures 2 , 3

TYPE MATERIAL: The holotype (ROM 105786), an adult female preserved as skin, skull, skeleton, and tissue, was collected in the vicinity of Alto Tambo by Mark Engstrom, Burton Lim, and Francisco Sornoza (original number F40079 ) on 3 March 1996 . One paratype is an additional female (ICN 13649) collected by Alberto Cadena, Pilar Rivas, and Robert P. Anderson (original number ACG 2765) at La Guarapería on 12 March 1995 .

DISTRIBUTION: Currently known only from northwestern Ecuador and southwestern Colombia (fig. 1), but perhaps widespread throughout the lower to middle elevations of the southern biogeographic Choco´. Because exhaustive mammal inventories in neotropical forests west of the Andes have been restricted to Barro Colorado, Panama, and La Selva, Costa Rica (Voss and Emmons, 1996), it is likely that the known distribution is just an artifact of inadequate collecting, compounded with superficial similarities to L. robusta and L. handleyi . In particular, specimens of L. handleyi reported from the western slopes of the Cordillera Occidental of Departamentos of Valle and Nariño, Colombia, and specimens of Lonchophylla sp. from the Pacific lowlands of Ecuador ( Alberico and Orejuela, 1982; Alberico, 1987; Albuja, 1999) deserve investigation.

ETYMOLOGY: For the Choco´, an area of endemism comprising tropical and subtropical humid forests west of the Andes from western Panama through Colombia to northern Ecuador.

DIAGNOSIS: A large­sized species of Lonchophylla (forearm 45–48 mm; weight 19– 23 g) with chocolate­brown to chestnut­colored dorsal fur and brown ventral fur; dorsal and ventral hairs bicolored (the former more distinctly banded than the latter), 7–8 mm long in shoulder region; pinnae short with rounded tips; thumb large (7.5–8.3 mm); fringe of the uropatagium sparse; calcar shorter than foot; palate long; with postpalatine torus; right and left upper I1 meet at distal third of the crown; large gap present between I1 and I2, and smaller gap between I2 and C; outer upper incisors (I2) pointed ventrally more than ventromedially; upper canines large; height of P3 slightly less than P4; gap present between C and P3; smaller gap present between P3 and P4; P4 with small but well­developed lingual cusp; M1 and M2 roughly the same width; lower incisors small and trilobed, with crown height approximately equal to crown width.

Of the characters listed above, five are particularly useful for field identification of Lonchophylla chocoana : size (forearm 44–48 mm; weight 19–23 g); thumb length (7.5–8.3 mm); dorsal fur color; ventral fur bicolored; and trilobed lower incisors. Within the genus Lonchophylla this combination of traits is unique to L. chocoana . Appendix 1 summarizes the molecular data that prompted the investigation of morphological differentiation in L. chocoana . The average uncorrected pairwise sequence divergence of the mitochondrial cytochrome b gene of L. chocoana with respect to L. robusta from Colombia is 11.6%, to L. robusta from Panama is 12.3%, and to L. handleyi is 11.6%. These genetic distances are indicative of species­level differentiation, according to one recently proposed criterion ( Bradley and Baker, 2001).

MEASUREMENTS: Dimensions of both specimens of Lonchophylla chocoana are provided in table 1, and metrical comparisons with representative series of other large congeners within its range are summarized in table 2.

DESCRIPTION AND COMPARISON: Lonchophylla chocoana is the largest member of the genus, as large or slightly larger than handleyi , and larger than robusta , hesperia , and bokermanni ( tables 1–3; Taddei et al., 1983). Females are generally larger than males in robusta and handleyi ( table 2), and the two chocoana females ( table 1) are therefore probably larger than their male conspecifics. Although this might produce some overlap in measurements between female robusta and male chocoana , other nonmetric characters remain diagnostic.

From all other large Lonchophylla , chocoana can be unambiguously distinguished on the basis of fur coloration, forearm length, greatest length of skull, and palatal length. Additionally, chocoana can be distinguished from robusta on the basis of size of the thumb, greatest length of skull, palatal length, orientation and size of the outer upper incisors, and the relative size of gaps between I1, I2 and C, which are roughly equal in robusta . L. chocoana can be distinguished from handleyi on the basis of the furry fringe along the uropatagium, size of the thumb, the relative size of the upper canines, presence of a ridge along the posterior edge of the palate (postpalatine torus), and the well­developed lingual cusp on P4. Lonchophylla chocoana is larger than all remaining congeners in most anatomical dimensions. L. hesperia and bokermanni may reach similar length of skull, but they have greater skull length­to­width ratios and are absent from the known range of chocoana (see measurements in Taddei et al., 1983).

As with robusta and handleyi , the dorsal pelage of chocoana is composed of bicolored hairs with cream­white bases and brown tips. The length of the dorsal fur along the upper back in chocoana is approximately 7–8 mm, slightly longer than in handleyi and robusta (4.0– 7.5 mm). The ventral pelage of chocoana contrasts with both handleyi and robusta in being bicolored from neck to genital region, whereas in handleyi the ventral fur is exclusively beige­brown unicolored, while some robusta individuals (particularly females) show bicolored hairs around the neck but never in the abdominal region.

The cranial morphology of chocoana is similar to that of other members of the genus. L. chocoana has a relatively long rostrum, a small but noticeable anteorbital inflation, and a large braincase. Zygomatic arches are absent as in all other lonchophyllines, and the palate is the longest of any congener. Like all Lonchophylla , L. chocoana has a dental formula I2/2, C1/1, P2/3, M3/3 × 2 = 34. The inner upper incisors are large compared to the outer incisors and are separated by a gap from each other and from the canine. In the latter respect chocoana also resembles all other species of Lonchophylla .

Differences in the dentition are subtle, but they provide the means to distinguish species of Lonchophylla (see Hill, 1980). In chocoana the inner upper incisors have a small triangular gap between them, meeting at the distal third of the crown. This is unlike robusta , handleyi , mordax , and thomasi , all of which show a taller gap between the inner upper incisors, meeting at the distal quarter of the crown. The upper canines of chocoana are relatively and absolutely larger than those of robusta and handleyi . The posterior cusp of the upper canines of chocoana is blunt, similar to that of handleyi , while the posterior cusp is sharp in robusta , thomasi , and mordax (the latter shows variation between the two disjunct subspecific populations).

In chocoana P4 is longer than P3 (anteroposterior dimension), as it is in robusta , handleyi , mordax , and thomasi . The height (dorsoventral dimension) of P3 is either equal to or very slightly less than P4. Both robusta and handleyi have shorter (dorsoventral dimension) P3 than P4, while mordax and thomasi show upper premolars that are subequal in height. The basal lingual cusp on P4 is present and well developed in chocoana , robusta , and thomasi , less developed in mordax , and poorly developed or absent in handleyi . The first molar of chocoana is comparatively wide, and it is larger (both in anteroposterior and lateral dimensions) than M2, which in turn is larger than M3. Both robusta and handleyi have similar widths of M1 and M2, although M1 is longer (anteroposterior dimension) than M2, with overall smaller M3. The first two molars of thomasi and mordax are similar in length and height.

The lower outer incisors of chocoana are trilobed, as they are in thomasi . Lower incisors are rarely trilobed in robusta ; m. mordax has trilobed incisors, but m. concava does not; and incisors are bilobed in handleyi . The height of the lower incisors is roughly the same as the width of these teeth in all species of Lonchophylla . The lower premolar dentition of chocoana resembles that of handleyi . In robusta the maximum height (dorsoventral dimension) of the series corresponds to p3, and the maximum length (anteroposterior dimension) corresponds to p4. In handleyi , p4 is the highest and longest tooth of the series, and in comparison the p4 of chocoana is narrow (lateral dimension). In contrast, the longest lower premolar of thomasi and mordax is p2. The height of the premolars in thomasi is roughly the same throughout the premolar series, whereas in mordax p4 is the highest premolar (dorsoventral dimension). The first molar of chocoana is the widest and longest of the molar series. This is the same condition as in handleyi , although m1 of handleyi is slender in comparison. In robusta the m1 is slightly wider (lateral dimension) than m2, which in turn is wider than m3. In robusta m1 is the longest molar (anteroposterior dimension). The differences among the molars are less marked in mordax and thomasi , particularly the latter. Although m1 is the longest molar (anteroposterior dimension) in both species, height and width vary only slightly along the series.

The coronoid process in Lonchophylla chocoana is high and oriented at an angle of about 110° with respect to the toothrow, as in robusta . In handleyi the coronoid process projects at an angle of around 130°. Both thomasi and mordax show even greater angles, as well as a longish (anteroposterior dimension) coronoid process in comparison to their larger congeners.

NATURAL HISTORY

Both known specimens of Lonchophylla chocoana were captured in ground­level mist nets. The notes on the specimen from Alto Tambo indicate that it was captured along with other glossophagines ( Anoura spp. ) in a disturbed secondary forest in nets left open overnight due to continuous rain (Burton Lim, personal commun.). The specimen from La Guarapería was also captured in secondary forest, between dusk and 2200 hours, along with Anoura caudifera , A. cultrata , and A. geoffroyi ( Cadena et al., 1998) . The survey in Nariño additionally captured Lonchophylla robusta and L. mordax within the same general region at the Altaquer locality. Both specimens were captured in early March: at Alto Tambo on 3 March 1996, and at La Guarapería on 12 March 1995.

Although these data are scant, some aspects are noteworthy. First, L. chocoana currently seems rare in its range; one specimen from Alto Tambo prompted this investigation, and the search for conspecifics only found 1 more among 11 specimens of largebodied Lonchophylla from west of the Cordillera Occidental of Colombia. As noted above, a few large Lonchophylla from western Colombia and Ecuador reported in the literature might correspond to chocoana . Only further sampling can document the complete range and the rarity of chocoana . Second , as with other Lonchophylla , chocoana can be captured using ground­level mist netting. At Paracou , French Guiana, and in southern Venezuela, most L. thomasi were captured using ground­level mistnets ( Handley, 1976; Simmons and Voss, 1998), as were all L. robusta individuals of the Smithsonian Venezuelan Project ( Handley, 1976) and all L. robusta from Tambito, Colombia ( Dávalos and Guerrero, 1999). Third, the habitat associated with the capture of L. chocoana has been characterized as disturbed, and the simultaneous capture of other glossophagines probably indicates the presence of local food resources, regardless of the habitat condition.

Little is known about the ecological niche of species in this genus, but observed diversity in body size and habitat choice (from dry scrub to lowland rainforest) indicates that there is some sort of partitioning in feeding and roosting ecology. These ecological characteristics become more intriguing now that three species of Lonchophylla have been found in similar habitats, as they were in the western slopes of the Cordillera Occidental of Nariño, Colombia ( Cadena et al., 1998).

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APPENDIX 1 VARIABLE SITES OF CYTOCHROME B IN LARGE NORTHERN SOUTH AMERICAN SPECIES OF LONCHOPHYLLA L. robusta Panama = ROM 104268; L. robusta Colombia 1 = MHN 512­514; L. robusta Colombia 2 = MHN 515; L. handleyi Peru 1 = AMNH 230214; L. handleyi Peru 2 = TTU 46164; and L. chocoana Ecuador = ROM 105786. Molecular sequences generated as part of the lonchphylline study have been deposited with GenBank under accession numbers AF423079­AF423101. — = same base as the one immediately above.

Fig. 2. Dorsal (A), ventral (B), and lateral (C) views of the skull of the holotype of Lonchophylla chocoana (ROM 105768). Scale bar = 5 mm.

Fig. 3. Anterior views of the lower dentition of Lonchophylla chocoana (left, ROM 105786) and L. robusta (right, ICN 13648, male). Note the shape and height of the gap between inner upper incisors and the trilobed lower incisors in chocoana. These morphological traits can be used in conjunction with size and other characters for field identification.