Thomas, 1902
Great Evening bat
External characters (Table 87)
This is one of the largest Vespertilionid bats (Iio1) with an average forearm length of 74.1 mm (70.9-77.3 mm). Externally, it resembles a large Eptesicus serotinus (Ese4). The ears are broad, with the tips rounded-off and the breadth subequal to the height. The tragus of each ear is one third the height of the pinna. The face is essentially naked with the nostrils simple and outward facing. The wing membranes are black above and below. The interfemoral membrane is also dark above but distinctly paler below. The tail is long, its tip is extruded some 6 mm from membrane. The wings are attached to the outer metatarsal of each foot. The pelage is a uniform grey-brown above, with a slight glossy sheen when viewed in some lights (Iio2). The ventral surface is a uniform matt grey brown. The baculum is most comparable in form to that of Eptesicus with a greatest length of 1.88 mm and a greatest width of 1.15 mm (Topal, 1970b).
Cranial characters
The skull (Iio3) is very robust with an average condylo-canine length of 25.7 mm (25.2-26.2 mm). It is comparable in general morphology to that of Eptesicus serotinus (Fig. 174). The rostrum is broad and flat with well developed lachrymal projections. The zygomata are widely flared, especially posteriorly. The braincase is ovoid in outline with prominent flanges in the mastoid region. The sagittal crest is low anteriorly but rises to a prominent lambda which forms the most posterior part of the skull. The lambdoid crests are strongly developed and overhang the supraoccipital. The dorsal profile is essentially straight, rising gently from the nasal aperture to the lambda. The anterior emargination of the palate extends back to the level of the posterior part of canines. The palate and mesopterygoid space are comparable to that of E. serotinus but in contrast there are two well developed basisphenoid pits in the floor of the braincase. The tympanic bullae are not greatly inflated and the basioccipital is broad. Each half mandible is robust with the coronoid process tall and bluntly pointed; the angular process is better developed than that of E. serotinus and projects beyond the condyle.
Dentition
- Upper toothrow length (C-M3) averages 10.7 mm (10.5-11.0 mm); the teeth are robust. The first upper incisor (I2) is large and broad, with a trace of a secondary cusp. The second upper incisor (I3) is minute, subequal in height to the cingulum of I2 (Fig. 186). The upper canine is powerful (Fig. 187), its cingulum with an indication of a cusp medially. The first upper premolar (PM2) is minute and situated internally to the toothrow. The second premolar (PM4) is large and in contact with the canine (Fig. 188). The protocones of M1 and M2 are well developed; the hypocones are virtually absent; the metacone is the predominant cusp in both teeth and the metastyle exceeds the mesostyle in size. M3 is not as reduced as that of E. serotinus (Fig. 175), it includes three commissures and a small metacone; there is a trace of a fourth commissure.
- In the lower dentition, there are three overlapping incisors. The lower canine has a well developed cingulum and a cingular cusp posteriorly. The first lower premolar (pm2) is less than half the crown area of the second (pm4). pm4 exceeds the trigonid of m1 in size; it has a small but well developed antero-internal cusp. m1 and m2 have the talonid slightly exceeding the trigonid in size. m3 has the talonid reduced to about half the crown area of the trigonid.
Variation
All specimens from the Indian subcontinent are provisionally referred to the nominate subspecies Ia i. io.