Pteronotus fulvus (Thomas, 1892)

Don E. Wilson & Russell A. Mittermeier, 2019, Mormoopidae, Handbook of the Mammals of the World – Volume 9 Bats, Barcelona: Lynx Edicions, pp. 424-443 : 438

4.

Thomas's Naked-backed Bat

Pteronotus fulvus

French: Ptéronote fauve / German: Thomas-Nacktriickenfledermaus / Spanish: Pteronotus de Thomas

Taxonomy. Chilonycteris davyifulvus [sic] Thomas, 1892 ,

“Las Penas, west coast ofJalisco,” Mexico.

Pteronotus fulvus was formerly classified as a subspecies of P. davyi , but here it is considered a distinct species. Monotypic.

Distribution. From Sonora and Tamaulipas S along Pacific and Gulf coasts of N Mexico, respectively, to El Salvador and W Honduras.

Descriptive notes. Head-body ¢.48-52 mm, tail 20-23 mm, ear 17-18 mm, hindfoot 11 mm, forearm 40-5-46-7 mm; weight ¢.7-8: 7 g. Thomas’s Naked-backed Bat is the smallest species of naked-backed bat. Dorsal and head pelage colors range from dark brown to bright orange; ventral hairs have grayish white tips. Rostrum is broad but comparatively narrower than in other species of naked-backed bats. Braincase is oval and less robust than in Davy’s Naked-backed Bat ( P. davyi ). Condylo-basal lengths are 13-7-15 mm. Individuals from Honduras and El Salvador are larger on average than in other areas of its distribution; a marked increase in overall size is also observed in the northernmost distributional limit in Sonora, Mexico. Additional external and cranial features shared with other species in the subgenus Pteronotus are listed in descriptive notes for Davy’s Nakedbacked Bat.

Habitat. Tropical dry forest, usually lowland habitats, mostly below 600 m. Thomas's Naked-backed Bat is abundant throughoutits distribution. It has narrow thermal specificity for roosting and is usually reported from hot caves (higher than 30°C), with 27°C being the lowest recorded roost temperature. This physiological limitation probably restricts habitats occupied by Thomas’s Naked-backed Bat.

Food and Feeding. Thomas’s Naked-backed Bat feeds mainly on dipterans, lepidopterans, and dermapterans, but diversity of insects included in diets might increase when prey abundance is low.

Breeding. Thomas’s Naked-backed Bat is seasonally monoestrous, with most females giving birth in the beginning of the rainy season. Maternity colonies mostly contain females, but males might be present in small numbers. In Mexico, mating occurs in January—March. Pregnant females are reported in April-May, with embryos ofvariable sizes (3-20 mm), and lactating females in July-September.

Activity patterns. Thomas’s Naked-backed Bat has a bimodal activity pattern, which seems to correspond to abundance peaks of crepuscular and nocturnal insects. It typically forages along riparian corridors, in open places 2-10 m aboveground, over water surfaces, and in forest trails. Echolocation calls during search phase consist of short CF-FM pulses of c.6 milliseconds. Second harmonic, which is the most intense, has two short CF components at 68-71 kHz and 58-60 kHz, joined by a FM downward sweep.

Movements, Home range and Social organization. Thomas’s Naked-backed Bat roosts in hot and humid caves and usually forms large colonies. Fluctuations in colony sizes are commonly reported and are probably related to seasonal movements due to reproductive activity. It exhibits a limited tolerance to low temperatures, which probably excludes it from temperate areas in its northernmost distribution. It has been suggested that mountain peaks and the Isthmus of Tehuantepec ( Mexico) act as physical barriers to dispersal of Thomas’s Naked-backed Bats.

Status and Conservation. Not assessed on The IUCN Red List. Thomas's Naked-backed Bat is included under Davy’s Naked-backed Bat, which is classified as Least Concern.

Bibliography. Arriaga-Flores et al. (2012), Avila & Medellin (2004), Birney et al. (1974), GBIF Secretariat (2017), Guevara-Chumacero et al. (2010), O'Farrell & Miller (1997), Pavan & Marroig (2016), Rydell et al. (2002), Salinas-Ramos et al. (2015), Smith (1972), Torres-Flores et al. (2012).

Figures

1. Antllean Ghost-faced Bat (Mormoops blainuviller), 2. Peters’s Ghostfaced Bat (Mormoops megalophylla), 3. Davy’s Naked-backed Bat (Pteronotus davyi), 4. Thomas's Naked-backed Bat (Pteronotus fulvus), 5. Big Naked-backed Bat (Pteronotus gymnonotus), 6. Macleay’s Mustached Bat (Pleronotus macleayii), 7. Sooty Mustached Bat (Pleronotus quadridens), 8. Wagner's Lesser Mustached Bat (Pteronotus personatus), 9. Dobson’s Lesser Mustached Bat (Pteronotus psilotis), 10. Parnell’s Common Mustached Bat (Pteronotus parnellii), 11. Hispaniolan Common Mustached Bat (Preronotus pusillus), 12. Puerto Rican Common Mustached Bat (Pteronotus portoricensis), 13. Mexican Common Mustached Bat (Pteronotus mexicanus), 14. Mesoamerican Common Mustached Bat (Pteronotus mesoamericanus), 15. Allen’s Common Mustached Bat (Pleronotus fuscus), 16. Paraguana Common Mustached Bat (Pteronotus paraguanensis), 17. Womurs Common Mustached Bat (Pteronotus rubiginosus), 18. Amazonian Common Mustached Bat (Pteronotus alitonus)

Distribution. From Sonora and Tamaulipas S along Pacific and Gulf coasts of N Mexico , respectively, to El Salvador and W Honduras .