Molossops mastivus Thomas, 1911 Molossidae Don E. Wilson Russell A. Mittermeier 8Q88J Thomas 1911 [809,1157,2156,2206] Mammalia Molossidae Cynomops Animalia Chiroptera 22 641 Chordata species mastivus   55.   Thomas's Dog-faced Bat   French: Grand Cynomope/ German: Thomas-Bulldogfledermaus/ Spanish: Cynomop de Thomas   Taxonomy. Molossops mastivus Thomas, 1911,   “Bartica Grove, Lower Essequibo,” Cuyuni-Mazaruni, Guyana.   Cynomops mastivuswas previously considered a subspecies of C. abrasus, but a recent revision based on molecular and morphological data elevated it to a full species. Monotypic.    Distribution.Known from scattered localities in lowlands of N South America, from E slopes of Andes in Ecuadorto E Venezuela, the Guianas, and Brazilian Amazon.   Descriptive notes.Head-body 74-88 mm, tail 32-44 mm, ear 16-20 mm, hindfoot 10-13 mm, forearm 41-8-51-2 mm; weight 27-54-8 g. Males are larger and heavier than females. Thomas's Dog-faced Bat is the largest Cynomops. Dorsal pelage is dark reddish brown with uniformly brown venter, similar to or slightly paler than dorsum; pelage is silky, but dorsal fur is not long (c. 4 mmat shoulder); dorsal hairs are weakly bicolored, with basal one-third pale buff. Face is blackish and virtually naked. Upper lip and dorsal border of narial region are smooth. Triangular blackish ears are slightly separated from each other on forehead (space less than 4 mm). Patagium, feet, and tail are also blackish. Propatagium is narrow, and posterior plagiopatagium is inserted lateral to base of feet. There is dark chocolate-brown fur along basal one-third offorearm and along adjacent propatagium. A patch of fur extends from posterodorsal surface of distal plagiopatagium, next to wrist, to fourth dactylopatagium. Skull is robust, with sagittal and occipital crests consistently well developed in males. Anterior face of lacrimal ridges forms abrupt angle with forehead, and nasal process of premaxilla is well developed, with lateral margin of external nares vertically straight, particularly in males, and less markedly in females. Incisive foramina are located relatively close to accessory foramen. Lowerjaw is massive with a convex corpus along its length (mainly in males), and there is a large shallow trigonid on M,.   Habitat.Tropical lowland rainforests from sea level to elevations of 534 m. The species is present in primary and secondary forests.   Food and Feeding.Thomas’s Dog-faced Batis an aerial insectivore, and insects of the order Coleopterahave been recorded in its diet in Amazonian Brazil.   Breeding.Reproductive data are scarce, but lactating females were recorded in July in Guyanaand a male with scrotal testes was captured in July in Manaus, Brazil.   Activity patterns.One specimen was captured at ¢.19:00 h in Suriname. Thomas’s Dogfaced Bat has been captured in mist nets set alongside or over rivers, and next to ponds in clearings of mature forests. It was also caught in canopy nets set 18-30 m aboveground.   Movements, Home range and Social organization.Six individuals from Manaus, were recorded sharing a roost in leaves of a buriti palm ( Mauritia sp., Arecaceae) with six individuals of Trumbull’s Bonneted Bat ( Eumops trumbulli).   Status and Conservation. Notassessed on The [UCN Red List.   Bibliography.Bernard (2001), Eger (2008), Handley (1976), Moras et al. (2016), Reis & Peracchi (1987), Simmons & Voss (1998), Tirira (2012b, 2017), Uieda & Taddei (1980), Williams & Genoways (1980a), Warner et al. (1974). 3780789401 22 641