Tomopeas ravus Miller, 1900

Velazco, Paúl M & Kline, Kerry A, 2019, Tomopeas ravus (Chiroptera: Molossidae), Mammalian Species 51 (979), pp. 70-74 : 70-72

Tomopeas ravus Miller, 1900

Peruvian Crevice-dwelling Bat

Tomopeas ravus Miller, 1900:571 . Type locality “Yayan, Cajamarca, Peru (alt. 1000 metres).”

CONTEXT AND CONTENT. Context as for genus, no subspecies are recognized.

NOMENCLATURAL NOTES. The phylogenetic affinities of Tomopeas have been a major topic of debate. Miller’s (1900, 1907) inclusion of Tomopeas in the family Vespertilionidae and in its own subfamily Tomopeatinae Miller, 1907 was accepted in several subsequent studies (e.g., Cabrera 1958; Honacki et al. 1982; Koopman 1993, 1994; Eisenberg and Redford 1999), even though Miller’s (1900) description of the genus and species hinted at a potential membership in the family Molossidae based on the morphology of the tragus. After reviewing newly collected specimens, Davis (1970) recommended the placement of Tomopeas in its own family; however, the placement of Tomopeas in the family Vespertilionidae was not challenged until the use of allozymes and mitochondrial DNA ( Sudman et al. 1994) found Tomopeas to be sister to all the other members of Molossidae ; this relationship was corroborated with morphological data by Simmons (1998). Currently, Tomopeas is located in the family Molossidae in its own subfamily Tomopeatinae ( McKenna and Bell 1997; Simmons 2005; Barkley 2008; Gregorin and Cirranello 2016). Vernacular names for Tomopeas ravus are blunt-eared bat, Peruvian crevice-dwelling bat, murciélago de orejas romas, and murciélago peruano de grietas ( Simmons 2005; Barkley 2008; Pacheco et al. 2009; Pari et al. 2015).

DIAGNOSIS

Tomopeas ravus , the sole member of the monotypic subfamily Tomopeatinae , is distinguished from other vespertilionoids by a unique combination of external and skull morphology characters, including: ears with a low, rounded tragus and a small, well-developed antitragus lacking a basal lobe; anteriorly projected pinnae; broad upper lip, slightly wrinkled, conspicuously fringed with hairs, and extends over the lower lip; tubular nostrils; tail is enclosed in the uropatagium, except for the last two vertebrae, which extend beyond the interfemoral membrane; thin uropatagium with visible fascicles of transverse layers of muscle; lateral “brush” of hairs absent on pedal digit length, 4.5–6.0 (n = 23); ear length, 11.0–16.0 (n = 18); forearm length, 31.0–35.0 (n = 25–– Miller 1900; Aellen 1965; Davis 1970; Velazco et al. 2013; Zamora et al. 2014; Pari et al. 2015). Ranges of selected craniodental measurements (mm; parenthetical n) were: greatest length of skull, 11.4–13.2 (n = 21); zygomatic breadth, 6.5–7.6 (n = 19); mastoid breadth, 6.1–6.8 (n = 18); least interorbital breadth, 2.8–3.8 (n = 21); palate length, 4.3–5.0 (n = 16); length of maxillary toothrow, 4.2–4.8 (n = 21); width across molars, 4.7–5.3 (n = 18); greatest mandible length, 7.9–9.8 (n = 17); length of mandibular toothrow, 4.6–5.0 (n = 20–– Miller 1900; Aellen 1965; Davis 1970; Velazco et al. 2013; Zamora et al. 2014; Pari et al. 2015).

The skull is narrow, with the braincase and rostrum flattened ( Fig. 2 ). The rostrum is considerably more than one-half as long as the braincase with a distinct median groove. The sagittal crest is absent. The palate is slightly concave longitudinally. The pterygoids are parallel, enclosing a nearly square space. The pterygoid hamuli are minute and slightly bent inward. The auditory bullae are large and their diameter noticeably exceeds the space between them. Basisphenoid pits are absent ( Fig. 2 ; Miller 1907). I; dorsoventrally flattened skull with a conspicuous shallow depression in the middle of the nasals; flattened disc-shaped auditory bullae; second lower incisor trifid; seventh cervical and first thoracic vertebrae fused ( Miller 1907; Davis 1970; Barkley 2008; Gregorin and Cirranello 2016).

GENERAL CHARACTERS

Tomopeas ravus is a small bat (2–4 g, n = 19–– Davis 1970, Velazco et al. 2013; Zamora et al. 2014; Pari et al. 2015). The dorsal pelage is long (about 8 mm) and pale brown; the venter is dull buff to whitish cream buff ( Fig. 1 ). The basal one-half of the fur on the dorsum and venter is dull gray. The skin on the face, ears, and membranes is blackish ( Fig. 1 ). The face and proximal one-half of the ears are furred. Metacarpals III and IV are subequal in size, with metacarpal V being the smallest ( Miller 1907). The calcar is similar in length to the tibia ( Miller 1900).

Ranges (mm; parenthetical n) for external measurements of T. ravus were: total length, 67.0–85.0 (n = 22); tail length, 29.0–45.0 (n = 23); tibia length, 10.0–11.0 (n = 9); hind foot

DISTRIBUTION

Tomopeas ravus is endemic to the coastal desert of Peru ( Fig. 3 ; Velazco et al. 2013; Pari et al. 2015). The elevational range is from near sea level (Piura) to near 2,300 m (Cajamarca). The type locality is Yayán in the department of Cajamarca (coordinates not available). Loaiza Salazar and Pacheco Torres (2017) erroneously reported the coordinates of another locality (Tolón) of Tomopeas as those of the type locality. No fossils are known.

FORM AND FUNCTION

The hairs of Tomopeas ravus present denticulate, coronal scales ( Benedict 1957). The dental formula is i 1/2, c 1/1, p 1/2, m 3/3, total 28. The upper incisor is strongly curved backward and less than one-half the height of the canine ( Fig. 2 ). The upper incisor cingulum forms a small but distinct inner basal cusp. The lower incisors are subequal and trifid. The upper canine is slightly curved backward. The cingulum of the lower canine forms a distinct anterior basal lobe. The upper premolar is relatively large, its crown area is more than 75% that of the first molar, very slightly emarginate posteriorly, its protocone is well developed ( Fig. 2 ; Miller 1907). The protocone of the first and second upper molars is well developed. The lingual borders of the inner first and second upper molars have a noticeable concavity between the protocone and hypocone ( Fig. 2 ; Miller 1907). The upper third molar is similar to the other upper molars in buccolingual width ( Fig. 2 ). The metacone of the upper third molar is well developed ( Fig. 2 ; Miller 1907).

The width of the cochlea relative to the basicranium in T. ravus is among the smallest in bats. The contribution of the cochlear volume to the whole bony labyrinth is 68.6%. The coiling of the cochlear canal completes two turns. The estimated height of the spiral of the cochlea is 1.07 mm. There is a large apical lacuna at the apex of the cochlear spiral. The secondary bony lamina is visible on the outer edge of the first turn. The bony channel for the vestibular aqueduct leaves the inner ear medial and anterior to the vestibular aperture of the common crus, then gently curves and opens on the surface of the petrosal near the dorsal end of the common crus. The angle between the anterior and lateral semicircular canals is 75° and between the posterior and lateral is 107°. The anterior and lateral semicircular canals deviate substantially from their planes (out-of-plane curvature) and the posterior canal is mostly planar. The anterior and lateral semicircular canals extend to the same level anteriorly. T. ravus has one of the smallest cochlear among molossids ( Velazco and Grohé 2017a). Three-dimensional surface models of the bony labyrinth of one individual are available in a public repository ( Velazco and Grohé 2017b).

The tongue of Tomopeas and all other molossids present a well-defined median dorsal lobe that it is separated from the more anterior portion of the tongue by a deep groove at the base, that divides the tongue into anterior and posterior regions ( Gregorin 2003). The basal papillae on the tongue of Tomopeas are conical, whereas in all other molossids the basal papillae are rounded ( Gregorin 2003).

Figures

Fig. 2.—Dorsal, ventral, and lateral views of skull and lateral view of mandible of the adult male Tomopeas ravus (CEBIOMAS [Colección de Mastozoología, Centro de Ecología y Biodiversidad, Lima, Peru] 226) from Quebrada Pariñas, 9.6 km NE of Talara, district of Pariñas, province of Talara, department of Piura, Peru. Greatest length of the skull is 12.3 mm.

Fig. 1.—A subadult female Tomopeas ravus (MUSA [Museo de Historia Natural de la Universidad Nacional de San Agustín de Arequipa, Arequipa, Peru] 12202) from Quebrada San Juan, province of Pisco, department of Ica, Peru. Photograph by Hugo Zamora used with permission.

Fig. 3.—Geographic distribution of Tomopeas ravus and associated Andean topography. Localities of sampled specimens obtained from collections records and literature are indicated by circles.