Sturnira tildae de la Torre, 1959

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 : 124-125

Sturnira tildae de la Torre

Figures 48–50

VOUCHER MATERIAL: 14 females (AMNH *266240, *266241, *266251, *267167, *267460, *268554, *268556, *268557, *268560, 268561; MNHN *1998.615, *1998.616, *1998.617, *1998.618) and 11 males (AMNH *266243, *266244, *266247, *266253, *267461, *268558, *268559; MNHN *1998.619, *1998.620, *1998.621, *1998.622); see table 45 for measurements.

IDENTIFICATION: Characters that we found useful for distinguishing Sturnira tildae from S. lilium are discussed in the preceding species account and will not be repeated here. Descriptions and comparative measurements of S. tildae can be found in Goodwin and Greenhall (1961), Hill (1964), Marinkelle and Cadena (1971), Husson (1978), Genoways and Williams (1979), Swanepoel and Genoways (1979), Brosset and Charles­ Dominique (1990), and Ochoa et al. (1993). No subspecies of S. tildae are currently recognized (Koopman, 1994).

Our Paracou material agrees well with most (not all, see below) previous qualitative descriptions of Sturnira tildae , and measurements of our vouchers fall within the range of size variation previously reported for the species. In all of our specimens, m1 and m2 have low lingual cusps separated by a shallow notch.

As noted in the preceding account, Brosset and Charles­Dominique (1990: 536) indicat­ ed that some of the smaller French Guianan specimens they identified as Sturnira tildae had lower molars with ‘‘serrated’’ lingual margins (i.e., with tall cusps separated by a deep vertical notch on each tooth), a condition not seen in our material. Their systematic conclusions also differed significantly from ours:

Several of our specimens share the measurements and characteristics of a third species described in 1980 by Davis, Sturnira luisi . Davis compares the morphology of luisi with that of lilium , but, concerning tildae , says nothing more than [that] luisi is smaller than tildae . The specimens collected by us which correspond to the description of luisi are in fact tildae of small size... in our series of tildae , a continuum exists between these small specimens and the bigger ones, whose size corresponds to the classical descriptions. The serrated condition of the lingual edges of the lower molars is given as distinctive of luisi by Davis; the lower molars of our small specimens of tildae show the same characteristics.... This feature is characteristic of both luisi and tildae . Sturnira luisi probably represents tildae of small size, the taxon luisi being synonymous with tildae .

We are not convinced by this argument, which seems to be based entirely on molar morphology and body size. The form of the skull, particularly of the zygomatic arches, is very different in tildae and luisi . As described and figured by Davis (1980) and confirmed by our observations, luisi is characterized by zygomatic arches with maxillary processes that are not bowed outward, producing a triangular appearance when the arches are seen in dorsal or ventral view. In contrast, both tildae and lilium have outwardly bowed maxillary processes, so that the zygomatic outline appears much less triangular. The shape of the dental arcade also differs among these taxa: whereas the maxillary toothrows arch outward in tildae and lilium , the upper toothrows are nearly parallel in luisi (Davis, 1980; personal obs.). Pending documentation of a graded series of intermediates between tildae and luisi , these morphologically distinctive taxa should still be regarded as valid species.

FIELD OBSERVATIONS: We recorded 54 captures (possibly including some recaptures) of Sturnira tildae at Paracou, of which 51 were in ground­level mistnets and 3 were in elevated nets. Of the 51 ground­level captures, 1 was in well­drained primary forest, 7 were in swampy primary forest, 11 were in creekside primary forest, 1 was in closed­canopy secondary growth, 27 were in manmade clearings, and 4 were over roadside puddles. Of the three elevated­net captures, one was at 5–8 m above a treefall in creekside primary forest, and the other two were at 10– 13 m above a narrow dirt road.

Comparing ground­level capture­habitat frequencies between Sturnira species at Paracou (table 46), we note that S. tildae was captured significantly more often in primary forest than was S. lilium , a result consistent with Brosset and Charles­Dominique’s (1990) conclusions about these species based on sampling at other French Guianan localities.

In addition to captures positively identified as either Sturnira lilium or S. tildae by the characters described above, we also recorded 10 unvouchered captures of ‘‘ Sturnira sp.’’ in ground­level mistnets: 2 in well­drained primary forest, 2 in swampy primary forest, 2 in creekside primary forest, 3 in manmade clearings, and 1 over a roadside puddle. Presumably these bats represented one or both of the species documented by our voucher material, but diagnostic traits were not recorded before the animals were released.

Figures

Fig. 48. Dorsal (A) and ventral (B) views of the skull of Sturnira lilium (AMNH 266232; male) from Paracou. Dorsal (C) and ventral (D) views of the skull of S. tildae (AMNH 267461; male) from Paracou. Note the species differences in incisor morphology, size and shape of the molars, and relative breadth of the mesopterygoid fossa and mastoid region. Scale bars = 10 mm.

Fig. 49. Lateral views of the skull and lower jaw of (A) Sturnira lilium (AMNH 266232; male) and (B) S. tildae (AMNH 267461; male). Scale bars = 10 mm.

Fig. 50. Oblique view of the lower jaw of (A) Sturnira lilium (AMNH 266232; male) and (B) S. tildae (AMNH 267461; male). Note the different morphologies of the lingual cusps on the molar teeth: lilium is characterized by tall lingual cusps that are separated by a deep vertical notch on m1 and m2; by contrast, these cusps are lower and separated by shallower notches in tildae. Scale bars = 10 mm.