(Linnaeus, 1758)
Brown Long-eared bat
External characters (Table 73)
This is a small bat with an average forearm length of 38.1 mm (36.5-40.3 mm). However, the ears are grossly enlarged (Pau1) and are nearly equal in surface area to the head and body. They are joined across the forehead by a very narrow membrane (Pau2). Each ear is elongated and oval, with the anterior and posterior borders evenly convex and the tip bluntly rounded-off, without any defined point. A rounded lobe projects from the base of the anterior margin. The antitragal lobe is virtually absent. The tragus is about half the height of the pinna. Its anterior border is essentially straight, the tip bluntly pointed and the posterior border slightly convex; the posterior basal lobe is distinct and with a rounded-off tip. The ears are pale brown, semitranslucent and crossed with about twenty well defined transverse ridges. They are virtually hairless, except for the anterior margin of each pinna which has a fringe of very short hairs. The tail is long, exceeding the length of the head and body; it is entirely enclosed within the well developed interfemoral membrane, except for the extreme tip. The wings are short and broad, with the third metacarpal longer than the fourth and fifth. They are virtually naked and uniformly brown in colour. The interfemoral membrane is also essentially naked although there are some hairs adjacent to the body, above and below. The muzzle is of the normal Vespertilionid type. The nostrils open upwards and are extended backwards as narrow fissures; they are separated from each other by a well marked internarial groove (Pau3). The pelage is long, soft and dense on the back; it is shorter on the belly. The dorsal surface is buffy brown, with conspicuously dark hair roots. The ventral surface is paler grey-buff but also with dark roots. The baculum is diagnostic in comparison with that of P. austriacus . It has a slender shaft and two slender basal lobes (Fig. 148).
Cranial characters
The skull, with an average condylo-canine length of 14.0 mm (13.8-14.2 mm), is smaller than that of P. austriacus (Fig. 151) . The rostrum is narrow, with the width across the lachrymal region about half that of the braincase. The nasal aperture is ovoid, slightly constricted posteriorly and extending backwards more than halfway to the level of the anterior margin of the orbit. There is a narrow furrow on the upper surface of the rostrum. The postorbital region is only slightly constricted behind the bluntly angular posterior extremities of the supraorbital ridges. The zygomatic arches are not flared outwards; each zygoma is slightly expanded dorsally in its mid-part. The braincase is inflated but rather low; it is less elongated than that of P. austriacus . Its surface is smooth with the sagittal and lambdoid crests only weakly developed and scarcely detectable in some skulls. The lambda just projects behind the supraoccipital, forming the most posterior part of the skull. The palate is concave with a small anterior emargination; the post dental extension is long with a blunt median palatal spine. The tympanic bullae are large but relatively smaller than those of P. austriacus , in consequence the basioccipital region is broader. Each half mandible is slender with the bluntly triangular coronoid process moderately elevated above the condyle; the angular process is not as powerful and long as that of P. austriacus .
Dentition
- Upper toothrow length (C-M3) averages 5.2 mm (5.0-5.3 mm) and exceeds that of P. austriacus in length (Fig. 152). The first upper incisor (i2) is bicuspidate and greatly exceeds the second (i3) in size. The canine which has a well developed cingulum exceeds the second premolar (pm4) in height. The first upper premolar (pm2) is situated in the toothrow; its conical cusp is about one quarter or less the height of the canine, its crown area equal to that of i3. pm4 is without any indication of an antero-medial cusp. m1 and m2 are about equal in size; their cusps are rather low and the hypocones are virtually absent. m3 is half the crown area of m2; its metacone and third commissure are small but distinct.
- The three lower incisors are tricuspidate and slightly overlapping. The lower canine is weak; it has a distinct antero-medial cingular cusp which is situated above and behind the outer cusp of the third lower incisor (i3). The second lower premolar (pm3) is small, about half the crown area of the first (pm2); it is situated in the toothrow and is compressed between pm2 and the third premolar (pm4). m1 and m2 are about equal in crown area with the protoconid the tallest cusp. m3 has the talonid moderately reduced.
Variation
Specimens from the Indian subcontinent are provisionally referred to P. a. homochrous , with the taxon puck considered to be a junior synonym (Sanborn, 1950).
Taxonomic remarks
The type locality of homochrous was apparently incorrectly given as Nepal, for according to Scully, 1887 and Sanborn, 1950 this specimen was collected at Darjeeling; although Hinton and Fry, 1926 suggest it may have come from Sikkim.