Peropteryx macrotis (Wagner)

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 : 33-36

Peropteryx macrotis (Wagner)

Figures 19 , 20

VOUCHER MATERIAL: 2 females (AMNH *266006, *267396) and 3 males (AMNH *266005, *266007; MNHN *1995.843); see table 4 for measurements.

IDENTIFICATION: Brosset and Charles­Dominique (1990) recognized two small Peropteryx species in French Guiana that they identified as P. macrotis (originally de­scribed by Wagner [1843] based on a Brazilian specimen from Mato Grosso) and P. trinitatis (described by Miller [1899] based on four specimens from Trinidad). Previously, Sanborn (1937) and Goodwin and Greenhall (1961) had concluded that trinitatis was no more than subspecifically distinct from macrotis because specimens referable to these taxa are similar and were not then known from sympatry. Although Handley (1976) subsequently reported that P. macrotis and P. trinitatis occur sympatrically in Venezuela, he provided no discussion of diagnostic characters. In consequence, most recent authors (e.g., Jones and Hood, 1993; Koopman, 1993, 1994) have continued to recognize trinitatis as a subspecies of P. macrotis .

According to Brosset and Charles­Dominique (1990), Peropteryx macrotis and P. trinitatis can be distinguished in French Guiana based on size (e.g., forearm length 43.0–

47.0 mm, maxillary toothrow length 5.3–6.0 mm in P. macrotis , forearm 39.5–40.4 mm, maxillary toothrow 4.7–4.8 in P. trinitatis ), skull shape (shorter, more rounded in P. trinitatis ), and ear and tragus shape (both narrower in P. trinitatis ). They also observed differences in sexual dimorphism (females larger than males in P. macrotis but not in P. trinitatis ) and social behavior (social groups of 1–4 individuals in P. macrotis , much larger [> 100] in P. trinitatis ). Unfortunately, all of their observations concerning P. trinitatis were based on a single colony from which only two specimens (one male and one female) were collected ( Brosset and Charles­Dominique, 1990).

Our voucher material from Paracou appears to represent the same species that Brosset and Charles­Dominique identified as Peropteryx macrotis despite some discrepancies in measurements. Whereas all measurements of the two females in our sample (table 4) fall within the range of variation they reported for female P. macrotis (op. cit.), the forearm measurements of our three males (39.7, 40.1, and 42.2 mm) correspond more closely to values they reported for P. trinitatis . Examination of skull shape and ear morphology, however, suggest that all of our specimens represent P. macrotis sensu Brosset and Charles­Dominique. Therefore , if there are two diagnosable taxa of small Peropteryx in French Guiana, it appears that males cannot be distinguished on the basis of forearm measurements alone.

To test our identification of the Paracou specimens, we compared our series with the adult female holotype (AMNH 7496) of Peropteryx trinitatis . The forearm of the holotype measures 41.9 mm, much smaller than those of either of our Paracou females. Although the skull of the holotype is badly damaged, the rostrum and toothrows remain largely intact (fig. 20). The maxillary toothrow length of AMNH 7496 is 5.21 mm, and the breadth across the upper molars is 5.74 mm, values that likewise fall well below those of our female Paracou vouchers (table 4) and of the female specimen identified as P. macrotis by Brosset and Charles­Dominique (1990). We also noted one qualitative difference between the holotype of trinitatis and our voucher material: the anterior upper pre­ molar is peglike and lacks well­defined anterior and posterior cusps in trinitatis , but this tooth is larger and has a distinct posterior cusp in the Paracou specimens. Paratypes (AMNH 7493, 7494, 7495) and topotypes (AMNH 175556, 175558, 175559) of trinitatis resemble the holotype in size and also have tiny, peglike anterior upper premolars.

According to Carter and Dolan (1978), the holotype of Peropteryx macrotis is an uncatalogued adult female preserved in alcohol at the Naturhistorisches Museum Wien. Unfortunately, the skull is missing and presumed lost. However, the forearm measurement of the holotype reported by Carter and Dolan, 45.8 mm, corresponds closely with that of our female specimen from Paracou (45.0 mm) and with those identified as P. macrotis by Brosset and Charles Dominique (43.9– 47.0 mm). These measurements are larger than, and do not overlap with, measurements previously reported for females of P. trinitatis (e.g., by Goodwin and Greenhall, 1961). We therefore follow Brosset and Charles­ Dominique in referring the larger of the two small Peropteryx from French Guiana to P. macrotis .

FIELD OBSERVATIONS: We captured only five individuals of Peropteryx macrotis , all of them at roosts. One roosting group of three bats (two adult males and one adult female) was found beneath the broken trunk of a fallen tree cantilevered about 1.5 m above the ground in well­drained primary forest (fig. 16). Another group of three individuals (of which only one adult male and one subadult female were captured) was found in a large hollow log (ca. 60 cm in inside diameter), also in well­drained primary forest.

Figures

Fig. 19. Dorsal (A), ventral (B), and lateral (C) views of the skull of Peropteryx macrotis (AMNH 266005; male) from Paracou. Scale bar = 5 mm.

Fig. 20. Close­up lateral views of the upper right dentition of (A) Peropteryx macrotis (AMNH 267396; female) from Paracou and (B) the holotype of P. trinitatis (AMNH 7496; female) from Trinidad. Occlusal views of the upper right dentition (C) P. macrotis (AMNH 267396; female) and (D) the holotype of P. trinitatis (AMNH 7496; female) are shown below. Note the species difference in morphology of the anterior upper premolar. Scale bars = 5 mm.