Saccopteryx gymnura Thomas, 1901

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 : 40-42

Saccopteryx gymnura Thomas

Figure 22

VOUCHER MATERIAL: 2 males (AMNH *267843; MNHN *1995.862); see table 8 for measurements.

IDENTIFICATION: Characters and measurements of Saccopteryx gymnura were discussed by Thomas (1901b) and Sanborn (1937). No subspecies are current recognized (Koopman, 1994).

Our material of Saccopteryx gymnura from Paracou represents a range extension of approximately 900 km for this species, which was previously known only from a few localities along the lower Amazon in Brazil (Koopman, 1994). Despite this considerable geographic hiatus, the Paracou specimens conform closely with published descriptions of the holotype (Thomas, 1901b; Sanborn, 1937) and are indistinguishable from other Brazilian material referable to S. gymnura (AMNH 93519, 93520; USNM 392995, 460080).

The only species that might be confused with Saccopteryx gymnura is S. canescens . Although similar in size, these tiny bats can be distinguished unambiguously by (1) dorsal fur color (dark brown in gymnura , brown with strong grayish or yellowish frosting in canescens ), (2) dorsal fur markings (stripes absent or very faint in gymnura , a pair of white stripes always visible and often bright in canescens ), (3) ventral fur banding (unicolored dark brown in gymnura , bicolored black or dark brown with tan tips in canescens ), (4) origin of the posterior part of the wing membrane (from the metatarsals in gymnura , from the tibia in canescens ), and (5) length of the forearm (33.5–35.3 mm in gymnura , 35.8–40.8 mm in canescens ). Although there is some species overlap in length of the maxillary toothrow, our specimens of gymnura have shorter toothrows (4.6 mm) than those previously reported for specimens of canescens (4.9–5.0 mm) from French Guiana ( Brosset and Charles­Dominique, 1990).

FIELD OBSERVATIONS: Both of our specimens of Saccopteryx gymnura were captured in ground­level mistnets, one in a small clearing bordered by well­drained primary forest (fig. 2), the other over a narrow dirt

road bordered by secondary growth but with well­drained primary forest nearby (fig. 11). Both captures were made shortly after dark (18:55–19:15 hours).

Figures

Fig. 22. Dorsal (A), ventral (B), and lateral (C) views of the skull of Saccopteryx gymnura (MNHN 1995.862; male) from Paracou. Scale bar = 5 mm.