Neoeptesicus, Cláudio & Novaes & Gardner & Nogueira & Wilson & Maldonado & Oliveira & Moratelli, 2023

Cláudio, Vinícius C., Novaes, Roberto L. M., Gardner, Alfred L., Nogueira, Marcelo R., Wilson, Don E., Maldonado, Jesús E., Oliveira, João A. & Moratelli, Ricardo, 2023, Taxonomic re-evaluation of New World Eptesicus and Histiotus (Chiroptera: Vespertilionidae), with the description of a new genus, Zoologia (e 22029) 40, pp. 1-24 : 13-15

Neoeptesicus gen. nov.

https://zoobank.org/ 1D855992-1B95-467D-93B4-3EC478240212

Eptesicus Rafinesque, 1820: 2 ; part.

Adelonycteris H. Allen, 1892: 466 ; part; replacement name for Vesperus Keyserling & Blasius, 1839 , preoccupied.

Type species: Vespertilio innoxius Gervais, 1841 .

Other species: Neoeptesicus brasiliensis (Desmarest, 1819) ; N. furinalis (d’Orbigny & Gervais, 1847) ; N. andinus (Allen, 1914) ; N. diminutus (Osgood, 1915) ; N. chiriquinus (Thomas, 1920) ; N. taddeii ( Miranda, Bernardi & Passos, 2006) ; N. ulapesensis ( Sánchez et al., 2019) ; N. langeri ( Acosta et al., 2021) ; and N. orinocensis ( RamÍrez-Chaves et al., 2021) .

Distribution: Neoeptesicus is a Neotropical genus, widely distributed across South America, and Central America. In Central America it is restricted to the southern mainland, with only the species Neoeptesicus furinalis and N. brasiliensis ranging northward into Mexico.

Diagnosis: Neoeptesicus can be distinguished by the following characters: ears short (<20 mm) and not connected; postorbital process of the jugal weakly developed; eyes comparatively small, with diameter smaller or about the same size as height of lower canines and diameter of nostrils ( Fig. 1 ); auditory bullae small, basioccipital region is larger than the width of each auditory bullae; length of dorsal fur usually short (averaging 8 mm); length of forearm ranging from 31.4–48.8 mm (averaging 40.1 mm); tragus short and rounded, smooth and slender; GLS 12.9–18.0 mm (averaging 15.8 mm); and MTL 4.5–7.0 mm (averaging 5.8 mm).

Description: Neoeptesicus includes small-sized to medium species, with forearm length ranging from 31.4 to 48.8 mm. Dorsal fur usually short (LDF 4.5–13.1 mm), less than 10 mm for most species; hairs ranging from blackish and unicolored to strongly bicolored; dark basal color extending from 1/2 to almost the entire length of hairs; the contrast between bands ranges from faint to strong; tips of hairs ranging from blackish to golden orangish or yellowish. Ventral fur usually short (LVF 4.3–11.8 mm), less than 8 mm for most species; hairs bicolored with dark brown bases from 1/2 to about 4/5 of hairs length, tips of hairs ranging from dark brown to nearly white.Wing membranes naked, usually dark brown. Plagiopatagium attached to the base of the toe. Dorsal surface of the uropatagium somewhat paler than wing membranes, nearly naked with short sparse hairs that do not extend beyond the knees. Ventral surface of the uropatagium brown and sparsely haired near the base of the tail. Ears well separated, medium sized, usually dark brown, and with rounded tips; tragus wider at the base, straight to slightly curved, long and rounded. Muzzle broad and inflated.

Skull delicate to robust; rostrum short, wide, and flattened, weakly sloping upwards to the braincase; braincase slightly wider than the rostrum. Posterior region of the braincase ranging from rounded, regular to straight, slightly projected upwards. Nasal opening V- to U-shaped. Frontal expanded laterally towards the orbit. Sagittal and lambdoidal crests weakly to well developed, connected or not; occipital helmet weakly- to well developed. Triangular, flattened bony plate where the sagittal and lambdoidal crests connect ranging from absent to well developed, the region where crests connect may be enlarged. Zygomatic arches thin and slightly widened medially. Basisphenoid pits absent. Palate extends well beyond molars, ending in a concave posterior edge, with a weakly-developed to small medial spine.

Dental formula is I 2/3, C 1/1, P 1/2, M 3/3 (×2) = 32. I 1 separated, ranging from slender and weakly bilobed to spatulate and strongly bilobed; wide and short to long and narrow, with inner and outer cusps weakly- to well-developed. I 1 usually about three to four times the size of I 2. I 1 usually not aligned to I 2 on a transversal axis of the skull. I 2 and C 1 usually separated by a small gap, C 1 with two slightly concave faces on the lingual region, and one slightly concave face on the labial region. P1 well-developed, reaching 1/2 of C 1 in height; P 1 in contact with C 1 and molars. M 1 and M 2 about the same size, almost square shaped, with W-shaped cusps. M 3 reduced, triangular, with only 3 cusps. I 1 to I 3 reduced, trilobed, and fully occupying the space between canines. P 2 about three times P 1 in height. Molars have well-developed cusps and decrease in size from M 1 to M 3.

Comparisons: Neoeptesicus most resembles Eptesicus , and both can be distinguished from Histiotus based on several characters. Ears in Histiotus are greatly enlarged,> 21 mm (21–39 mm, usually> 25 mm); in Neoeptesicus and Eptesicus ears are comparatively reduced, <20 mm (8–20 mm, usually <18 mm); the tragus in Histiotus is notched and long, with total length> 10 mm (10–20 mm); in Neoeptesicus and Eptesicus the tragus is smooth and short,> 12 mm (4.8–12 mm); there is no overlap when the length of tragus is analyzed together with ear and forearm length. The ears in Histiotus are connected by a membrane of variable development, while in Neoeptesicus and Eptesicus this membrane is absent. Eyes in Histiotus are larger than nostrils and lower canines, and smaller or about the same size as nostrils or canines in Neoeptesicus and Eptesicus . The skull in Histiotus is narrow and long (mean value of GLS / BAM = 2.7) when compared to Neoeptesicus and Eptesicus (mean value of GLS / BAM = 2.3); the auditory bullae are comparatively twice as large in Histiotus than in Neoeptesicus and Eptesicus ; and Histiotus has a well-developed postorbital process of the jugal, which is weakly developed in Neoeptesicus and Eptesicus .

The morphologically similar genera Neoeptesicus and Eptesicus can be distinguished using the following set of characters: length of dorsal fur, usually> 10 mm in Eptesicus and <10 mm in Neoeptesicus ; the only exceptions are N. andinus and N. chiriquinus , which can be differed from Eptesicus by the dark and nearly unicolored fur, with only the tips of dorsal hairs washed with lighter color. Length of ventral fur, usually> 8 mm in Eptesicus and <8 mm in Neoeptesicus ; the only exceptions, again, are N. andinus and N. chiriquinus . Color pattern, with strongly bicolored dorsal fur in Eptesicus , with the basal 1/2 of hairs dark brown and distal 1/2 brownish to golden brown; and ventral hairs also bicolored with the basal 2/3 of hairs dark brown, and distal 1/3 grayish yellow. In Neoeptesicus the pattern of dorsal and ventral fur color is highly variable, with most species presenting a different color combination than found in Eptesicus ; dorsal fur can vary from unicolored to strongly bicolored and ventral fur can vary from dark brown to whitish, the few species that have the same pattern of color as Eptesicus can be easily differentiated based on other characters such as length of fur, length of forearm, and cranial characters. Length of forearm usually> 42 mm in Eptesicus , and usually <45 mm in Neoeptesicus ; species that overlap in size can be separated on other diagnostic characters; the only species of Neoeptesicus that overlap in both size and distribution with Eptesicus are N. brasiliensis and N. chiriquinus , two species that can be easily distinguished from Eptesicus based on length and color of dorsal fur. The skull in Eptesicus is robust, with well-developed crests and helmet, the crests are always connected and the triangular plate where lambdoidal and sagittal crests converge is always absent; in Neoeptesicus the shape of skull and development of these cranial features is highly variable, and only some of the largest species show the pattern seen in Eptesicus ; again these species can be easily distinguished from Eptesicus by the combination of the characters described above. The length of skull is> 17 mm in Eptesicus and usually <18 mm in Neoeptesicus , with no overlap when compared together with forearm length. Eptesicus is mainly distributed across North and Central Americas, overlapping in distribution only with N. andinus , N. brasiliensis , N. chiriquinus , and N. furinalis .

See Table 3 for additional comparisons.

Figures

Figure 1. Representatives of New World Eptesicus: (A)Eptesicus taddeii and (B)Eptesicus fuscus; Histiotus: (C)Histiotus velatus; and Old World Eptesicus: (D) Eptesicus serotinus. Authorship of images: (B) Dr. Burton Lim and (D) Adrià López-Baucells, http://www.batmonitoring.org.