Artibeus (Dermanura) cinereus (Gervais)

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 : 104-108

Artibeus (Dermanura) cinereus (Gervais)

Figures 41 , 42

VOUCHER MATERIAL: 9 females (AMNH *266259, *266265, *266266, *266270, *267499, *267991; MNHN *1995.1108, *1995.1109, *1995.1110) and 16 males (AMNH *266260, *266261, *266290, *266291, *266302, *266306, *266307, *266320, *267196, *267978, *267980; MNHN *1995.1111, *1995.1112, *1995.1113, *1995.1114, *1995.1115); see table 39 for measurements.

IDENTIFICATION: The most recent revision of the smaller species of Artibeus (subgenus Dermanura ) is Handley’s (1987), whose meticulous species comparisons and key were our primary resource for identification. Additional comparative measurements of A. cinereus and A. gnomus from French Guiana provided by Brosset and Charles­Dominique (1990) were also helpful. Although both species probably occur in Surinam and may have been mixed in earlier collections, Husson’s (1962, 1978) account of A. cinereus seems to have been based entirely upon specimens properly referred to that species. Koopman (1994) listed seven subspecies of A. cinereus , however all but two of these appear to represent other species (see Handley, 1987, and below).

Our voucher material, one of the largest series of Artibeus cinereus reported from a single locality, conforms in all respects to Handley’s (1987) description of the species. Although our specimens generally fall within the range of morphometric variation previously reported in the literature, a few individuals of both sexes are slightly smaller in some dimensions than those documented from the Guianas by Husson (1962, 1978) and Brosset and Charles­Dominique (1990).

As with the larger species of Artibeus (subgenus Artibeus ), we found that we could not always distinguish species of Dermanura in the field. Most individuals of cinereus are larger than most specimens of gnomus (table 39), and most cinereus have cream­colored ear margins and tragus while those structures are bright yellow in most gnomus . However, we captured some individuals that we initially misidentified using these characters. Of 67 collected specimens of Dermanura , 65 (97%) were correctly identified in the field; two individuals (3%) were initially identified incorrectly, both cases involving specimens of A. cinereus (one male and one female) misidentified as A. gnomus . We had to clean the skulls of these and several other specimens that fell in the zone of size overlap between A. cinereus and A. gnomus (see table 39) in order to determine their correct identifications.

We are unaware of any external characters that allow unequivocal identification of Artibeus cinereus and A. gnomus where these taxa occur in sympatry, but the number of lower molars appears to be reliable in our Paracou sample: all individuals with two lower molars present on both sides proved to be A. cinereus upon subsequent examination, and all individuals with three lower molars on both sides were A. gnomus (one individual of cinereus had two lower molars on one side and three on the other). Although the number of lower molars is perhaps the best single character for distinguishing these taxa in the field, it is not very useful for nonde­ structive research projects because m3 (when present) is small, translucent, and easily obscured by saliva; hence, we found it almost impossible to unambiguously determine if m3 was present in living bats.

Handley (1987) recognized two subspecies of Artibeus cinereus but did not discuss their distinguishing characteristics. Whereas specimens he identified as A. c. cinereus were listed from localites in central Amazonia on both sides of the river, specimens he assigned to A. c. quadrivittatus were from eastern Venezuela, Surinam, eastern Amazonia, and the northernmost part of the Brazilian Atlantic forest. Presumably, our material is referable to the latter taxon, the type locality of which is Surinam ( Husson, 1962, 1978). Measurements of the holotype of quadrivittatus provided by Husson (1962) fall entirely within the range of variation in our sample from Paracou.

FIELD OBSERVATIONS: We recorded 41 captures (possibly including some recaptures) of Artibeus cinereus at Paracou, of which 37 were in ground­level mistnets, 1 was in an elevated mistnet, and 3 were at roosts. Of the 37 ground­level mistnet captures, 1 was in well­drained primary forest, 5 were in swampy primary forest, 3 were in creekside primary forest, 1 was in a treefall opening in primary forest, 22 were in manmade clearings, and 5 were over roadside puddles. The single example taken in an elevated mistnet was captured 5–8 m above the ground in the subcanopy of swampy primary forest.

We found only a single roosting group of Artibeus cinereus , in a leaf­tent constructed from the bifid terminal leaflet of an immature understory palm provisionally identified as Astrocaryum sciophilum (figs. 43–45).

Figures

Fig. 41. Dorsal (A) and ventral (B) views of the skull of Artibeus cinereus (MNHN 1995.1112; male) from Paracou. Dorsal (C) and ventral (D) views of the skull of A. gnomus (AMNH 266314; male) from Paracou. Among other features, gnomus is distinguished from cinereus by its inflated anteorbital region and posteriorly constricted mesopterygoid fossa. Scale bars = 10 mm.

Fig. 42. Lateral views of the skull and lower jaw of (A) Artibeus cinereus (MNHN 1995.1112; male) and (B) A. gnomus (AMNH 266314; male). Note the species difference in number of lower molars. Scale bars = 10 mm.