170.

Humboldt’s Big-eared Brown Bat

Histiotus humboldti

French: Sérotine de Humboldt / German: Humboldt-GroRohrfledermaus / Spanish: Histiotus de Humboldt

Taxonomy. Histiotus humboldti Handley, 1996,

“Los Venados, 4 km NNW Caracas, 10°32’N, 66°54'W, 1498 m, Distrito Federal, Venezuela.”

Histiotus is phylogenetically nested within Eptesicus closely related to the New World species and some authors have included Histiotus as a subgenus of Eptesicus . Histiotus 1s recognized here as a distinct genus because of its distinct morphology, however, leaving Eptesicus paraphyletic, which may result in the splitting of Eptesicus into multiple genera. Venezuelan specimens previously reported as “ Histiotus sp. A ” by C. O. Handley, Jr. in 1976 and “ Histiotus sp. ” by A. L. Gardner in 1990 correspond to H. humboldti . It has a disjunct distribution that is probably related to a relictual wider distribution. Monotypic.

Distribution. N, W & S Venezuela, NC & SW Colombia, and C Ecuador.

Descriptive notes. Head-body ¢.54-59 mm, tail 47-56 mm, ear 28-32 mm, hindfoot 8-11 mm, forearm 44-49 mm; weight 9-12 g. Dorsal hairs are bicolored, with blackish bases and bright tan to brown tips; ventral hairs have fuscous bases and buff tips. Ears are very large; anterior lobe is wide, forming point at its fold; tragus is relatively short and broad. Skull is fragile; braincase and postorbital constriction region are notably inflated; rostrum is short, narrow, and shallow; zygomatic arches have strongly developed postorbital process; facial profile is sharply dished; and pterygoid processes are thin and delicate. Teeth are small and delicate, with low cusps; lower molar tooth row is relatively short. Dental formula for all species of Histiotusis12/3,C1/1,P1/2,M 3/3 (x2) = 32.

Habitat. Montane regions below cloud forests and paramos and lower montane humid forests, secondary growth moist evergreen forests, scrubby tepuyan vegetation in open areas, sub-Andean woodlands, and eucalypt plantations at elevations of 1500-3000 m.

Food and Feeding. Humboldt’s Big-eared Brown Bat is insectivorous.

Breeding. Pregnant Humboldt’s Big-eared Brown Bats were captured between late January and early February in Colombia.

Activity patterns. No information.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Data Deficient on The IUCN Red List. Humboldt’s Big-eared Brown Bat is uncommon to rare in its fragmented distribution.

Bibliography. Gardner (1990), Handley (1976, 1996), Handley & Gardner (2008), Rodriguez-Posada (2010), Romero (2018b), Simmons (2005), Velazco & Aguirre (2016b).