Sturnira bidens (Thomas, 1915)

Don E. Wilson & Russell A. Mittermeier, 2019, Phyllostomidae, Handbook of the Mammals of the World – Volume 9 Bats, Barcelona: Lynx Edicions, pp. 444-583 : 543

119.

Bidentate Yellow-shouldered Bat

Sturnira bidens

French: Sturnire bidentée / German: Gelbschulterfledermaus / Spanish: Sturniro bidente

Taxonomy. Corvira bidens Thomas, 1915 ,

“Bacza, Upper Coca River, Oriente [= Napo] of N. Ecuador. Alt. 6500’ [= 1981 m].”

The taxon bidens was the basis for a new genus, Corvira, which was later included as a subgenus of Sturnira . Recent phylogenetic analyses indicate that S. bidens is not closely related to S. nana , so if the name Corvira is used as a generic name again,it should only include S. bidens . Monotypic.

Distribution. Andean regions of W Venezuela, Colombia, Ecuador, and Peru.

Descriptive notes. Head-body 62-67 mm (tailless), ear 13-17 mm, hindfoot 14-16 mm, forearm 39-7-43-3 mm; weight 14-21 g. The Bidentate Yellow-shouldered Bat 1s medium-sized. Upperparts are variable, from pale brown to brown or dark grayish brown. Shoulder patches are almost indistinguishable. Underparts are dark brown. Pelage is soft and woolly, with long (7-8 mm) dorsal hairs having 3-4 bands; almost whitish basal band can be absent in populations near Merida (north-western Venezuela). Tail membrane is very short and densely furred. Forearm, femur, and adjacent parts of wings are sparsely haired, but legs and feet are densely furred. Skull is relatively long, narrow, and anteriorly sloping, with weak or incomplete zygomatic arches. There is a single pair of lower incisors (I) and small molars and premolars separated by narrow gaps. Dental formulais12/1,C1/1,P 2/2, M 3/3 (x2) = 30. Chromosomal complement has 2n = 30 and FN = 56. It is similar to most known karyotypes of species of Sturnira in having an acrocentric Y-chromosome.

Habitat. Andean forests at elevations of 1700-3000 m (mostly above 2200 m). The Bidentate Yellow-shouldered Bat is found in evergreen and cloud forests, although it can be netted on forest edges and secondary forests.

Food and Feeding. Being a highland specialist, diet of the Bidentate Yellow-shouldered Bat is comparatively less diverse than other species with broader elevational ranges. It includes at least 17 plant species in its diet, mostly fruits of Solanum (Solanaceae) . Other fruits include Vismia (Hypericaceae) , Ficus (Moraceae) , Piper (Piperaceae) , and Anthurium (Araceae) . Lack of insects in several dietary studies might indicate that it is strictly frugivorous, which would be reinforced by its sedentary habits.

Breeding. In central Peru, pregnant Bidentate Yellow-shouldered Bats were recorded in August. More extensive data from Merida conform to bimodal polyestry. Pregnancy and lactation should occur through the year, with at least two peaks of pregnancy: February-March (end of dry season) and June-July (short dry season). This means parturition occurs right before rainy seasons begin.

Activity patterns. Bidentate Yellow-shouldered Bats are nocturnal. Activity peaks in first two hours after dusk, with lower peaks throughout the night. Only known roost is a cave in Colombia.

Movements, Home range and Social organization. High recapture rate of Bidentate Yellow-shouldered Bats at the Cordillera de Mérida could indicate they have small and rather fixed home ranges (or foraging areas).

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Bidentate Yellow-shouldered Bat has a wide distribution and presumably large populations.

Bibliography. Baker (1979), Castano et al. (2018), Gardner (2008g), Gardner & O'Neill (1969), Molinari & Soriano (1987), Pacheco & Patterson (1991), Velazco & Patterson (2013).

Figures

119. Bidentate Yellow-shouldered Bat (Sturnira bidens), 120. Lesser Yellow-shouldered Bat (Sturnira nana), 121. Arata-Thomas Yellow-shouldered Bat (Sturnira aratathomasi), 122. Honduran Yellow-shouldered Bat (Sturnira hondurensis), 123. Burton's Yellow-shouldered Bat (Stwrnira burtonlimi), 124. Highland Yellow-shouldered Bat (Sturnira ludovici), 125. Adriana’s Yellow-shouldered Bat (Sturnira adrianae), 126. Tschudi’s Yellow-shouldered Bat (Sturnira oporaphilum), 127. Mistratoan Yellow-shouldered Bat (Sturnira mistratensis), 128. Soriano’s Yellow-shouldered Bat (Sturnira sorianoi), 129. Choco Yellow-shouldered Bat (Sturnira koopmanhilli), 130. Talamancan Yellow-shouldered Bat (Sturnira mordax), 131. Perla Yellow-shouldered Bat (Sturnira perla), 132. Tilda’s Yellow-shouldered Bat (Sturnira tildae), 133. Hairy Yellow-shouldered Bat (Sturnira erythromos), 134. Bogota Yellow-shouldered Bat (Sturnira bogotensis), 135. Greater Yellow-shouldered Bat (Sturnira magna), 136. Northern Yellow-shouldered Bat (Sturnira parvidens), 137. Baker's Yellow-shouldered Bat (Sturnira bakeri), 138. Little Yellow-shouldered Bat (Sturnira Lilium), 139. Gianna’s Yellow-shouldered Bat (Sturnira giannae), 140. Dominica Yellow-shouldered Bat (Sturnira angeli), 141. Paulson’s Yellow-shouldered Bat (Sturnira paulsoni), 142. Luis’s Yellow-shouldered Bat (Sturnira luisi)

Distribution. Andean regions of W Venezuela , Colombia , Ecuador , and Peru .