248.

Allen’s Big-eared Bat

Idionycteris phyllotis

French: Oreillard d'Allen / German: Allen-Langohr / Spanish: Orejudo de Allen

Other common names: Lappet-browed Bat, Mexican Big-eared Bat

Taxonomy. Corynorhinus phyllotis G. M. Allen, 1916,

“ Mexico: San Luis Potosi (probably near the city of the same name).”

Previously placed in Plecotus but transferred to monotypic Idionycteris, based on morphological and chromosomal characters. Also using those characters, the genus had previously been synonymized with Euderma, but molecular reconstructions based on several mitochondrial and nuclear genes support the distinction of Idionycteris at the generic level; but relationships within tribe remain unclear. Two subspecies recognized.

Subspecies and Distribution.

IL p. phyllotis G. M. Allen, 1916 — C Arizona (SW USA) S to Michoacan (SC Mexico).

I. p. hualapaiensis Tumlison, 1993 — extreme S Nevada, S Utah, and N Arizona (SW USA).

Descriptive notes. Head-body c. 65 mm, tail 40-53 mm, ear 34-43 mm, hindfoot 9-12 mm, forearm 41-8-49- 9 mm; weight 8-16 g. Closely resembles Euderma and Plecotus distinguished from former by pair of lappets projecting over forehead from anterior base of ears, coloration, and presence of three lower premolars; from latter, by presence of lappets, keeled calcar, and nostrils not posteriorly elongated. Long dorsal fur (c. 10 mm) is soft, with blackish bases contrasting with yellowish-gray tips, and blackish patches on shoulders; ventral fur has black bases and pale bufftips; tufts of white hair can be found on posterior bases of ears. Ears large; tragus (12-14 mm long) conspicuous. Uropatagium has 12-13 transversalribs, scarce hairs on basal surface, and is attached to hindfoot. Supraorbital region of skull sharply ridged;sagittal crest absent; rostrum broad and flattened; braincase also broad and shallow. P? is small and crowded between C' and P*, in which main cusp is slightly higher than molar series cusps; M? is about one-half size of M! and M2. Dental formulais12/3,C1/1,P 2/3, M 3/3 (x2) = 36. Chromosomal complement has 2n = 30 and FN = 50, which is most similar to the Spotted Bat ( Euderma maculatum), differing by presence of medium-sized acrocentric autosome pair in Allen’s Big-eared Bat, rather than subtelocentric autosome pair.

Habitat. Mountainous wooded habitats, from forests to riparian woodlands; also found in arid habitats, such as desert shrub, mesquite grassland with scattered oaks, xeric scrub, and tropical deciduous forests. Commonly found in rocky areas with outcrops, cliffs, boulders or lava flows, and also near water, along streams or over ponds. Recorded at elevations of 403-3225 m, but commonest above 900 m.

Food and Feeding. Insectivorous, feeding mainly on small moths, but also soldier beetles, dung beetles, leaf beetles, cockroaches, and flying ants. Echolocation patterns and flight movements suggest it to be highly flexible in foraging, capturing prey in flight but also by gleaning; can forage within or below forest canopy.

Breeding. Pregnant females were recorded in June, all bearing a single embryo; lactating females from June to August. Flying young were reported at the end ofJuly.

Activity patterns. Most specimens were captured 1-5-2 hours after sunset, at the start of its activity period. Day roosts were found in caves, mine shafts, boulders, sandstone crevices, and lava beds, and under loose bark of ponderosa pine ( Pinus ponderosa, Pinaceae) snags. Echolocation calls are long CF/FM and FM sonar sounds. The long (20-200 milliseconds) CF sounds occur at 27 kHz, while FM sounds at end of call sweep down from 24 kHz to 12 kHz, with a second harmonic at 40-22 kHz.

Movements, Home range and Social organization. During summer females gather in maternity colonies of 25-150 individuals; males are probably solitary and roost at other sites. Recorded sharing roosts with Townsend's Big-eared Bat ( Corynorhinus townsend) and the Fringed Myotis ( Myotis thysanodes).

Status and Conservation. Classified as Least Concern on The IUCN Red List. Major threats are related to loss of roosting sites, including recreational and commercial activities in occupied roost sites, and timber management practices. Occurs in protected areas in Utah, Arizona, and New Mexico.

Bibliography. Anderson (1972), Amadoret al. (2018), Arroyo-Cabrales & Alvarez-Castafieda (2017e), Barbour & Davis (1969), Bat Conservation International (2018), Bogdanowicz, Juste et al. (2005), Bogdanowicz, Kasper & Owen (1998), Czaplewski (1983), Hall (1981), Handley (1959), Hayes et al. (2009), Ortega & Arita (2014c¢), Rabe et al. (1998), Roehrs et al. (2010), Simmons, J.A. & O'Farrell (1977), Simmons, N.B. (2005), Williams et al. (1970), Wilson & Ruff (1999).