Templeton, 1848
Dusky Leaf-nosed bat
External characters (Table 42a, Table 42b)
This is a small species of Hipposideros (Hat1), superficially similar to H. fulvus (Hfu1) but with a significantly shorter forearm (36.3 mm: 34.9-38.0 mm in H. a. ater ) and smaller ears. The breadth of the ears is subequal to their height and the tips are broadly rounded-off; each ear has a well defined antitragus. The noseleaf has a greatest width of about 4.0-4.5 mm. Its anterior leaf is without supplementary lateral leaflets or a median emargination. It is lightly covered in short, fine hairs and has a well defined internarial septum, which is triangular in shape, with a short base, long sides and a bluntly pointed tip. The septum separates the nostrils from each other; each nostril has a small narial lappet on its outer margin. The intermediate leaf is simple in form and has a slightly convex upper border. Like the anterior leaf, it is lightly haired and has at least four long vibrissae; it is not bulbous. The posterior leaf slightly exceeds the width of the anterior and intermediate leaves. It has an evenly rounded, convex anterior border and is subdivided by three ill-defined septa into four cells. There is a well defined frontal sac situated in the mid-line behind the posterior leaf. The feet are small. In the wing, the fourth metacarpal exceeds the fifth in length whilst the third is the shortest. The combined lengths of the phalanges of the third metacarpal greatly exceed the length of the metacarpal. The first phalanx of the fourth metacarpal exceeds the second in length. The tail is long and is enclosed, all except the extreme tip, within the well developed interfemoral membrane. The wings and interfemoral membrane are naked, above and below, and are a uniform dark brown/ black. The pelage is variable in colour ranging from dull yellow, golden-orange or pale grey to dark brown on the dorsal aspect. The hair bases are paler than the tips. The ventral aspect is also variable in colour but is usually paler than the back. Adults weigh 5-7 grams (Gopalakrishna, 1969). The baculum is very small. It has a thin straight shaft with a simple base and tip (Fig. 88).
Cranial characters
The skull (Fig. 85) is small with an average condylo-canine length of 13.6 mm (13.2-14.2 mm in H. a. ater ). There are four nasal inflations on the slightly rounded rostrum. The two anterior inflations are essentially rectangular in shape; the posterior ones are more spherical. There is no post-nasal depression. The sagittal crest, although present over the interorbital region, does not bifurcate to form supraorbital ridges. The braincase is bulbous, equal to or broader than the zygomata. The jugal bone of each zygoma has a well defined dorsal process posteriorly. There is a slight depression at the point of the fronto-parietal suture. The anterior border of the mesopterygoid space is V-shaped. The visible cochleae are about equal in size to the tympanic bullae. The coronoid process of each half mandible scarcely exceeds the height of the lower canine. The angular process is strongly developed and sharply angulated outwards.
Dentition
- Upper toothrow length (C-M3) averages 5.3 mm (5.1-5.7 mm). The upper incisor (I2) is small, wedge-shaped and with its cusp angled inwards. The upper canine is robust; it has a very shallow groove on its antero-lateral surface and a well defined cingulum. The first upper premolar (PM2) is small and displaced externally from the toothrow. The second premolar (PM4) and the canine are sometimes in contact. M1 and M2 have the typical W-shaped cusp pattern of insectivorous bats with the parastyle and metastyle better developed than the mesostyle. The metacone exceeds the paracone in size in M1 and to a lesser extent in M2. M3 slightly exceeds half the crown area of M2. It includes a parastyle, mesostyle and two commissures; sometimes there is a vestige of a third commissure posteriorly.
- Both the lower incisors are tricuspidate; the second (i2) is partly situated behind the first (i1). The canine is tall and slender. The first lower premolar (pm2) is about half to two-thirds the crown area of the second (pm4) (Fig. 91). The small premolar (pm3), often present in Rhinolophus (Fig. 79) is always absent. The protoconid is the dominant cusp in the lower molars. m3 is slightly reduced in height and crown area in comparison to m1 and m2.
Karyology
2N= 32, FN= 60. The karyotype is similar to that of H. fulvus . There are ten pairs of metacentric and 5 pairs of submetacentric autosomes. The X chromosome is a medium-sized submetacentric and the Y chromosome a small submetacentric (Ray-Chaudhuri et al., 1971).
Variation
Specimens from India and Sri Lanka are referred to H. a. ater . Specimens from the Nicobar Islands are provisionally referred to H. a. nicobarulae . They are of similar external appearance but average larger (Table 42b) and in contrast to H. a. ater , the jugal bone of each zygoma is without a dorsal projection.