Eptesicus chiriquinus Thomas

Simmons, Nancy B. & Voss, Robert S., 1998, The mammals of Paracou, French Guiana, a Neotropical lowland rainforest fauna. Part 1, Bats, Bulletin of the American Museum of Natural History 237, pp. 1-219 : 134-140

Eptesicus chiriquinus Thomas

Figures 55 , 56

VOUCHER MATERIAL: 2 females (AMNH *267531, *268584) and 4 males (AMNH *267234, *267530; MNHN *1995.961, 1995.962); see table 52 for measurements.

13 We examined dark, long­furred specimens of Eptesicus , clearly referable to Davis’ andinus group, from lowland areas of Brazil (Amazonas, Rio Madeira, Santo Antonio do Guajará [ca. 25 m]: AMNH 92251, 93787), French Guiana (Paracou [ca. 30 m]: AMNH 267234, 267530, 267531, 268584; MNHN 1995.961, 1995.962), and Panama (San Blas, Armila, Quebrada Venado [sea level]: USNM 335411). In addition, unambiguous descriptions of andinus ­group specimens have been reported in the literature from a lowland site in Venezuela (Bolívar, Imataca Forest Reserve [180 m]; Ochoa et al., 1993) and another in French Guiana (Piste Saint­Élie [ca. 45 m]; Brosset and Charles­Dominique, 1990).

IDENTIFICATION: In his revision of the South American species of Eptesicus, Davis (1966) recognized an andinus group of species with long blackish fur. Several taxa were included in this complex: andinus Allen (1914) , chiriquinus Thomas (1920b) , inca Thomas (1920b) , montosus Thomas (1920b) and chiralensis Anthony (1926) . Of these, Davis considered inca and chiriquinus to be strict junior synonyms of E. andinus , the larger of the two species he recognized; the smaller species, E. montosus , included chiralensis as a valid subspecies.

Koopman (1978) disagreed, claiming that the long­haired forms of Neotropical Eptesicus are restricted to cool highland areas, whereas the short­haired forms occur in the warm lowlands. By his interpretation, the long­haired taxa are local variants of shorthaired species that have adapted to cooler conditions at higher elevations. Accordingly, Koopman (1978, 1993, 1994) treated the members of Davis’ (1966) andinus group as subspecies of nomenclaturally older shorthaired species based on size, assigning andinus to E. brasiliensis , and montosus and chiralensis to E. furinalis . However, Koopman’s adaptive scenario concerning hair length is refuted by the occurrence of longhaired Eptesicus —clearly referable to Davis’ andinus group—in lowland areas of Brazil, Panama, Venezuela, and French Guiana. 13 In addition, the sympatric occurrence in northeastern Venezuela of E. brasiliensis , E. furinalis , and a third species that Ochoa et al. (1993) identified as E. andinus definitely indicates that Eptesicus species with different pelage types can coexist at the same elevation.

Specimen data cited by Davis (1966), together with other collections subsequently reported in the literature (e.g., by Handley, 1976), provide compelling evidence that two species referable to the andinus group are sympatric at several South American localities. However, Davis did not personally examine any of the relevant holotypes in this complex, so his decisions about synonymies are problematic. Because Koopman’s (1978) review of the situation was obviously not an improvement, a fresh appraisal of the systematics of Neotropical Eptesicus is necessary.

To determine the correct identification of several blackish, long­haired specimens of Eptesicus captured at Paracou, we examined the holotypes of E. andinus and E. chiralensis as well as 136 other specimens of Neo­ tropical Eptesicus in the collections of the AMNH, FMNH, and USNM. 14 We also consulted the original descriptions of E. chiriquinus , E. inca , and E. montosus (Thomas,1920b) , and we compared our observations with those reported by Davis (1965, 1966), Williams (1978), Brosset and Charles­ Dominique (1990), and Ochoa et al. (1993). Our conclusions, which differ substantially from those previously expressed in the literature, are explained below

Our side­by­side comparisons of the holotypes of Eptesicus andinus (AMNH 33807, from Valle de las Papas, Colombia) and E. chiralensis (AMNH 47219, from El Chiral, Ecuador) indicate that these forms are conspecific. Although the holotype of andinus is slightly larger than that of chiralensis (table 53), both share a similar skull morphology that is unusual in Eptesicus : the braincase appears domed rather than flattened when seen in profile, the sagittal and nuchal crests are very poorly developed, and the intersection of the sagittal and nuchal crests is marked by a flattened triangular plate of bone that is thicker than the surrounding braincase. The dorsal pelage of both holotypes is the same dark brown color (although the tips of the hairs are slightly lighter over the lower back in the holotype of andinus ), the length of the dorsal fur is the same (ca. 9 mm), and the length and coloration of the bicolored ventral fur (hairs with dark bases and tan tips) are also similar. In our view, these specimens represent a single species, the oldest name for which is Eptesicus andinus Allen (1914) .

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14 Specimens examined in addition to those from Paracou are listed here by species based on our revised identifications. Eptesicus andinus : Brazil (AMNH 134910), Colombia (AMNH 32671, 32802, 33807 [holotype]), Ecuador (AMNH 47218–47220), Peru (AMNH 23780, FMNH 123953), Venezuela (USNM 370934– 370938, 370943–370947, 370949–370953, 370955, 370962–370963, 387732, 441755, 441764). Eptesicus brasiliensis : Brazil (AMNH 78868–78871, 79535– 79538, 79645–79647), Colombia (AMNH 239096– 239098), Ecuador (AMNH 67606), Peru (AMNH 67232–67233, 74016), Venezuela (78387–78401). Eptesicus chiriquinus : Brazil (AMNH 92251, 93787), Colombia (AMNH 33806, USNM 483952), Costa Rica (USNM 566457), Ecuador (AMNH 47217, 47221– 47223, 67608; USNM 513502, 548349), Panama (USNM 306809–306810, 310258–310260, 319504, 331958–331968, 335411, 338098–338100, 387728, 387730–387731, 518026–518027, 520577–520579, 526246, 541105, 567879–567880, 575587–575590), Venezuela (USNM 387728, 387730–387731, 441765).

Although we have not examined the holotype of Eptesicus montosus , the original description and accompanying measurements suggest that it too is conspecific with E. andinus . Collected at El Choro, Bolivia, this specimen (BMNH 2.1.1.1) was described by Thomas (1920b: 363) as follows: ‘‘Fur very long and fine, hairs of back about 9 mm. in length. General colour blackish brown, lightened on the posterior back by the Prout’s brown of the tips of the hairs... skull, as compared with that of E. brasiliensis , conspicuously more swollen, higher in the braincase... the whole skull less flattened and less ridged.’’ Measurements of BMNH 2.1.1.1, a male, indicate that it is intermediate in size between the male holotypes of chiralensis and andinus (table 53).

Also apparently referable to Eptesicus andinus are two small specimens so identified by Thomas (1920b) from Chanchamayo, Peru, that Davis (1966) subsequently reidentified as E. montosus chiralensis (we have not seen these, but base our identification on their size and morphology as reported by Thomas and Davis). By contrast, another specimen (BMNH 94.8.6.1) collected at the same locality, the holotype of Eptesicus inca Thomas (1920b) , is clearly distinct. Eptesicus inca is larger than E. andinus in most dimensions (table 53) and, unlike the latter species, it has a well­defined sagittal ridge.

A third andinus ­group taxon named by Thomas (1920b) was E. chiriquinus , based on a specimen from Cerro Chiriquı´, Panama (BMNH 3.3.3.1). The holotypes of chiriquin­ us and inca are similar in most dimensions (table 53), and Thomas did not explain why he thought they were different species. In comparing their respective descriptions, only a 0.5­mm difference in postorbital breadth and a possible difference in wooliness of the pelage appear noteworthy. Although we have not seen these types, our examination of oth­ er specimens convinces us that the same large­bodied species of Eptesicus with long blackish fur occurs in Central and South America, and that such character differences do not hold up on examination of large series. Accordingly, we conclude, like Davis (1966), that chiriquinus and inca are conspecific. Since both chiriquinus and inca were named in the same publication, and because their relative precedence has not previously been established, we select chiriquinus as the senior epithet.

Based on the preceding inferences from examination of specimens and from the literature, we offer the following revised diagnosis of Eptesicus chiriquinus : a large species (for the genus) with long (8.0–10.0 mm) dark brown or blackish dorsal fur that appears oily in living individuals; ventral fur bicolored (each hair with a dark brown base and tan tip); skull with sagittal and nuchal crests well developed (even in smaller indi­ viduals); rostrum not laterally inflated; braincase high, not flattened, with well­defined dish­shaped facial profile; length of forearm> 42.0 mm; greatest length of skull>15.80 mm; zygomatic breadth> 10.70 mm; mastoid breadth> 8.40 mm; length of maxillary toothrow>6.10 mm; breadth across molars> 6.75 mm.

Eptesicus chiriquinus can be distinguished unambiguously from E. andinus on the basis of size (generally larger in chiriquinus ; see table 54), presence of well­developed sagittal and nuchal crests (absent in andinus ), and absence of a flattened, triangular plate of bone at the intersection of the sagittal and nuchal crests (present in andinus ). Eptesicus chiriquinus and E. andinus exhibit nonoverlapping measurements in the following dimensions: forearm length (females only), greatest length of skull, condyloincisive length, zygomatic breadth, maxillary toothrow length, and breadth across molars (males only). Eptesicus chiriquinus can be distinguished from E. brasiliensis on the basis of pelage (always longer and usually darker in chiriquinus ) and skull morphology (rostrum less inflated, braincase higher, and dish­ shaped facial profile more strongly developed in chiriquinus ).

Based on our examination of material in the USNM collected by the Smithsonian Venezuela Project, the specimens referred to Eptesicus montosus by Handley (1976) represent E. andinus in our usage, and the specimens he referred to E. andinus represent E. chiriquinus as diagnosed above (see footnote 14 for specimens examined). Based on published measurements, specimens of Eptesicus ‘‘ andinus ’’ reported from French Guiana by Brosset and Charles­Dominique (1990) and from Venezuela by Ochoa et al. (1993) probably represent E. chiriquinus .

The specimens of Eptesicus chiriquinus that we collected at Paracou are among the largest known representatives of this taxon (see tables 52–54). Although our preliminary comparisons suggested that the Paracou specimens might represent a distinct taxon, consideration of additional material (particularly from Panama) blurred all distinctions initially detected between the larger and smaller specimens referable to this species. In the absence of any clear pattern of geo­ graphic variation, we do not recognize any subspecies of E. chiriquinus .

FIELD OBSERVATIONS: Two of the six Eptesicus chiriquinus that we captured at Paracou were taken in ground­level mistnets and four were taken in elevated nets. Of the two ground­level captures, one was in a manmade clearing and one was over a roadside puddle. The four elevated mistnet captures were made between 4 and 23 m over a narrow dirt road. Although all of our vouchered captures were in modified habitats, we once caught a large, blackish vespertilionid in the uppermost mesh of a ground­level mistnet in swampy primary forest. Briefly entangled in full view but just out of reach before escaping, this bat closely resembled E. chiriquinus and differed in external appearance from oth­ er species known to occur at Paracou.

Figures

Fig. 55. Dorsal (A) and ventral (B) views of the skull of the holotype of Eptesicus andinus (AMNH 33807; male) from Colombia. Dorsal (C) and ventral (D) views of the skull of E. chiriquinus (AMNH 267234; male) from Paracou. E. chiriquinus has a consistently larger and more heavily built skull than does E. andinus. Also note the flattened, triangular bony plate at the intersection of the sagittal and nuchal crests in andinus, a structure never present in chiriquinus. Scale bars = 10 mm.

Fig. 56. Lateral views of the skull and lower jaw of (A) the holotype of Eptesicus andinus (AMNH 33807; male) and (B) E. chiriquinus from Paracou (AMNH 267234; male). Note the species difference in development of the sagittal crest. Scale bars = 10 mm.