Mimon bennettii (Gray)

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 : 79-82

Mimon bennettii (Gray)

Figures 34–37

VOUCHER MATERIAL: 1 female (AMNH *267109) and 1 male (MNHN *1995.988); see table 26 for measurements.

IDENTIFICATION: Although Koopman (1993, 1994) considered Mimon bennettii and M. cozumelae to be conspecific, many other authors have recognized them as distinct species ( Dalquest, 1957; Handley, 1960; Carter et al., 1966; Gardner and Patton, 1972; Jones and Carter, 1976; Swanepoel and Genoways, 1979; McCarthy, 1987; McCarthy et al., 1993). Whereas the restricted type locality of M. bennettii is Ipanema in the Brazilian state of São Paulo ( Hershkovitz, 1951), the type locality of M. cozumelae is Cozumel Island in the Mexican state of Quintana Roo ( Goldman, 1914). Currently, the known range of cozumelae extends from southern Mexico to northwestern Colombia, and that of bennettii extends from the Guianas to southeastern Brazil (Koopman, 1994).

Dalquest (1957) reported additional specimens of Mimon cozumelae collected in the decades following Goldman’s (1914) original description, and discussed differences between cozumelae and bennettii , which he treated as distinct species. However, as Handley (1960) subsequently noted, Dalquest’s only comparative example of bennettii was a juvenile. Schaldach (1964) subsequently summarized characters supposedly distinguishing these taxa, including size (smaller in bennettii ), dorsal pelage color (darker in bennettii , brighter in cozumelae ), and length and woolliness of the middorsal hairs (long and not woolly in bennettii , short and woolly in cozumelae ). Like Dalquest’s (1957) account, however, Schaldach’s description of the pelage of bennettii seems to have been based on juvenile or subadult specimens. Despite the morphological differences he noted, Schaldach concluded that bennettii and cozumelae are conspecific, a decision based in large part on the geographic gap between their known geographic ranges. Hall (1981) and Koopman (1993, 1994) followed Schaldach (1964) without additional discussion.

Contra Schaldach (1964), Hall (1981), and Koopman (1993, 1994), we consider Mimon bennettii and M. cozumelae to represent distinct species based on apparently consistent differences in the following characters: (1) dorsal pelage color (more reddish in adult bennettii , less reddish in cozumelae ), (2) col­ or of the wingtip (dark in bennettii , white in cozumelae ), (3) shape of the middle upper incisors (tapering to points in bennettii , more spatulate in cozumelae ), (4) form of the low­ er incisors (narrower in bennettii ), (5) morphology of m3 (talonid larger and better developed in bennettii ), and (6) morphology of the posterior palatal margin (broader with Ushaped mesopterygoid notch in bennettii , narrower with V­shaped notch in cozumelae ). 8 Although some overlap exists, bennet­

8 This list of characters is based on both literature accounts and our examination of voucher specimens. Specimens examined in addition to those from Paracou: Mimon bennettii (Brazil: USNM 123393, 391027); Mimon cozumelae (Mexico: AMNH 144508, 185862–185872).

tii is generally smaller than cozumelae (e.g., forearm length of 50.0–56.6 mm in bennettii , 54.6–60.7 mm in cozumelae ; Swanepoel and Genoways, 1979; Hall, 1981; Brosset and Charles­Dominique, 1990). Although these taxa have not been collected in sympatry, it is counterproductive to regard them as subspecies given the magnitude of their mor­ phological divergence; until proven false, the appropriate null hypothesis is that they represent distinct species.

Descriptions and measurements of Mimon bennettii sensu stricto were provided by Gray (1838), Dalquest (1957), Husson (1962, 1978), Hill (1964), Swanepoel and Genoways (1979), and Brosset and Charles­Dominique (1990). Our specimens closely resemble others previously reported from Guianas, particularly the bright orange­russet adults described by Brosset and Charles­Dominique (1990). Based on our limited comparisons, recognition of subspecies does not seem warranted.

FIELD OBSERVATIONS: One of our two specimens of Mimon bennettii was captured in a ground­level mistnet and the other was taken at a roost; both captures were in creekside primary forest. The roost site was a large tree (ca. 1.5 m in diameter at breast height) with a central cavity extending from ground level to near the crown. We surrounded the only roost opening at ground level, a small hole ca. 15 cm in diameter, with a mistnet enclosure that caught one adult male Mimon bennettii and 27 adult male Carollia perspicillata between 18:10 and 18:35 hours on 17 November 1992 (the Mimon bennettii emerged at 18:25 hours); no emerging bats escaped. We did not revisit this roost in subsequent years.

Figures

Fig. 34. Dorsal (A) and ventral (B) views of the skull of Mimon bennettii (MNHN 1995.988; male) from Paracou. Dorsal (C) and ventral (D) views of the skull of M. cozumelae (AMNH 265107; male) from Guatemala. Note the species differences in incisor morphology and in the shape of the mesopterygoid notch of the posterior palate. Scale bars = 10 mm.

Fig. 35. Lateral views of the skull and lower jaw of (A) Mimon bennettii (MNHN 1995.988; male) and (B) M. cozumelae (AMNH 265107; male). Scale bars = 10 mm.

Fig. 36. Anterior views of the upper and low­ er dentition of (A) Mimon bennettii (MNHN 1995.988; male) and (B) M. cozumelae (AMNH 265107; male). Note that the middle upper incisors of bennettii taper to points, whereas these teeth are more spatulate in cozumelae. Scale bars = 5 mm.

Fig. 37. Occlusal views of the crown of the right m3 in (A) Mimon bennettii (MNHN 1995.988; male) and (B) M. cozumelae (AMNH 265107; male). Note that the talonid is larger and better developed in bennettii than it is in cozumelae. Scale bars = 1 mm.