(E. Geoffroy, 1813)
Trident bat
External characters (Table 55)
This is a relatively small Hipposiderid bat with an average forearm measurement of 51.2 mm (50.1-52.3 mm). The tail is short and characteristically its tip protrudes some 3-5 mm from the poorly developed interfemoral membrane (Atr1). The ears are broad, the anterior margin is convex, the posterior border slightly concave, the tip pointed. In the noseleaf (Fig. 109), the anterior leaf is a simple structure without a median emargination. The median septum is not expanded and the narial lappets are little developed. There are two pairs of well developed supplementary leaflets. The intermediate leaf is a smooth and slightly protuberant structure with a gently convex upper border, its corners are continuous with the upper edges of the anterior leaf. The posterior leaf has three ill-defined septa that divide it into four shallow cells. There are three prominent projections on the upper surface (BW24). The central one is the highest and is narrowed to a sharp point; the two lateral ones are lower with their upper extremities blunt. In the wing, the third metacarpal is long, slightly exceeding the fourth in length, it greatly exceeds the fifth. The second phalanx of the third metacarpal is short, considerably less than half the length of the metacarpal. The pelage is relatively short, about 4 mm mid-dorsally; unlike Triaenops persicus , it does not extend on to the interfemoral membrane (Atr2). Extralimital specimens are variable in colour. Erythristic individuals are light orange-brown on the back. The hair bases are paler and show through on the crown of the head and shoulders. The belly is a rather lighter, clear orange brown. Other individuals are a very pale greyish brown on the back; the belly is paler buffy whitish throughout.
Cranial characters
The skull (Fig. 110) is small with an average condylo-canine length of 16.4 mm (15.7-17.0 mm). The rostrum is narrower than that of T. persicus ; it is relatively deep, comparable in height to the braincase. The nasal inflations are well developed but with a less flattened upper surface. The sagittal crest rises as a high knife-like blade in the interorbital region; in consequence the dorsal profile forms an even convex curve from the nasal inflation to the lambda. The lambdoid crests are well developed. In contrast to T. persicus , the zygomata are widely flared posteriorly and the dorsal expansions are less developed. The coronoid process of each half mandible is well developed, considerably higher than that of T. persicus (Fig. 106).
Dentition
- Upper toothrow length (C-M3) averages 6.8 mm (6.5-7.2 mm). The upper incisor (I2) is small, peg-like and not bicuspid (Fig. 111). The upper canine is powerful and possesses a well defined posterior cusp at about half to two-thirds its height; this cusp, in contrast to T. persicus , is not elevated into a point but instead has a straight edge at right angles to the tooth. There is no cusp anteriorly (Fig. 110). The small upper premolar (PM2) is absent and the large premolar (PM4) is in contact with the canine. M3 is comprised of a parastyle, metastyle and two commissures; it lacks any trace of a third commissure (Fig. 111).
- In contrast to T. persicus , the first lower incisor (i1) is tri- not bicuspidate. The lower canine is short and robust. The first lower premolar (pm2) has half the crown area of the second (pm4). m3 is greatly reduced with the talonid less than one quarter the crown area of the trigonid.
Variation
Specimens from Pakistan are referred to A. tridens murraiana on account of their generally large size but small ears and dark pelage (Owen and Qumsiyeh, 1987).