213.

Thomas's Yellow Bat

Rhogeessa io

French: Rhogeessa de Thomas / German: Thomas-Gelbfledermaus / Spanish: Rogesa de Thomas

Other common names: Southern Little Yellow Bat

Taxonomy. Rhogeessa io Thomas, 1903,

“Valencia [Carabobo], Venezuela.”

Previously considered a race of R. parvula, based on external and skull morphology; later included in R. tumida based on bacular, external and skull morphology; subsequently returned to full species status based on karyological studies. Overits wide distribution, this species probably includes additional subspecies or even species yet to be described; one south Central American specimen showed considerable genetic distance from Venezuelan and Trinidadian populations, indicating that they may correspond to different species; a taxonomic review is needed. Monotypic.

Distribution. C & SE Nicaragua S to N & W Colombia, NW Ecuador, Venezuela, and patchily in Guyana, Amazonian Brazil, and Bolivia; also San Andrés, Providencia, Trinidad, and Tobago Is.

Descriptive notes. Head—body 37-50 mm, tail 29-33 mm, ear 11-13 mm, hindfoot 5-8 mm, forearm 27- 6-32 mm; weight 3-6 g. Dorsal fur is bicolored, with whitish to grayish-yellow bases and cinnamon tips; ventral fur is tawny olive with paler bases. Ears blackish and triangular; tragus long. Eyes small, and face triangular. Wing membranes blackish brown and naked; uropatagium almost naked, sparsely furred only until knee. Skull short (greatest skull length less than 12- 6 mm) and broad; rostrum broad and flattened; braincase broad and low, with low but distinct sagittal crest; zygomatic arches broad and spread wide; helmet absent. I? has distinct secondary cusp near tip; molariform teeth relatively broad and heavy; palate broad. Chromosomal complement has 2n = 30.

Habitat. Wide variety of habitats, including evergreen and deciduous forest, thorn scrub, open areas and villages, occupying almost every vegetation zone at elevations from sea level to 1500 m. Commonly found in slightly disturbed deciduous forests.

Food and Feeding. Insectivorous, feeding on small flying insects that are captured on hunting routes along trails, roads, streams and wells, and clearings, often close to ground. Analyses of fecal samples from Venezuela showed that 100% of their volume was composed by coleopterans, mainly Scarabaeidae .

Breeding. Pregnant females were captured from February to April, lactating females from March to July, and flying juveniles from May to August. The scarce information available indicates that litter size is two.

Activity patterns. Nocturnal; this fast-flying bat initiates foraging activity right after sunset. Two peaks of activity, one in first hour of evening, and other in last hour before dawn. Roosts found in palm fronds, hollow trees, between boards, under thatched roofs and other human buildings. Echolocation search-phase calls have durations of 2:1-3-8 milliseconds, with maximum frequencies of 95-111 kHz and minimum frequencies of 33-42 kHz. Frequency at maximum energy 48-2-57-7 kHz.

Movements, Home range and Social organization. This species can roost in fairly large colonies; recorded roosting in a church tower along with Bonda Mastiff Bats (Molossus currentium), Sinaloan Mastiff Bats (M. sinaloae), Argentine Serotines ( Eptesicus furinalis), long-tongued bats (Glossophaga sp.), Common Black Myotis ( Myotis nigricans), and Lesser Bulldog Bats ( Noctilio albiventris).

Status and Conservation. Classified as Least Concern on The IUCN Red List. Widely distributed, with expected large population. It occurs in several protected areas.

Bibliography. Baird, Hillis et al. (2008), Baird, Marchan-Rivadeneira et al. (2012), Bianconi & Pedro (2017), Bickham & Ruedas (2008), Dolan & Carter (1979), Emmons & Feer (1997), Genoways & Baker (1996b), Goodwin (1958b), Goodwin & Greenhall (1961), LaVal (1973a), Oria & Machado (2007), Pio et al. (2010), Simmons (2005), Soriano & Tavares (2016).