(Thomas, 1913)
Wroughton's Free-tailed bat
External characters (Table 60)
This is a large Molossid with an average forearm length of 64.9 mm (63-67 mm). The ears are very large and connected to each other by a membrane over the forehead (Owr2). The anterior margin of each ear is dotted with a number of small horny points; the ear tip is broadly rounded and the posterior margin smoothly convex (BW24a). The tragus is triangular in shape and minute; there is no antitragus but there is a well developed extra lobe on the anterior border of the pinna. The face is essentially naked throughout. The nostril pad is prominent, projecting well beyond the anterior margin of the mouth; the openings to the nostrils are circular and face sideways. Beneath the nostrils are hairs that resemble a small moustache. The mouth is wide and fleshy and the eyes relatively large. The pelage is diagnostic in colour. On the dorsal surface, it is a rich glossy dark chocolate brown on the crown of head, back and rump; there is a thin white border on each flank, extending from the axilla to the groin, and on the antebrachial membranes. The shoulders and the nape of the neck are pale greyish white (Owr3). The ventral surface is dull brown but with a contrasting grey collar, variably extending onto the chin and upper chest (Owr4). There are dark hairs present on the underside of the wing to a line extending from the elbow to the mid-thigh. A small, shallow gular sac is present in both sexes. The hind feet are dark but with white hairs present on the external borders of the first and fifth digits.
Cranial characters
The skull (Fig. 126) is comparable in size to that of Tadarida teniotis with an average condylo-canine length of 22.5 mm (21.8-23.2 mm). It is smooth and well rounded with a marked concavity present on the upper braincase at the fronto-parietal suture (Owr5). The sagittal crest is poorly developed anteriorly and nearly obsolete posteriorly; it may just extend to lambda. The lambdoid crests are scarcely evident. The occiput is bulbous. The antero-external corners of the braincase are also prominent. The upper side of each zygoma has a very large postorbital plate. The premaxillae are not usually co-ossified; in consequence there is usually a small flask-shaped anterior palatal foramen which is widest posteriorly. The basisphenoid pits are deep and sharply defined; the edges are overhanging and the septum is well developed. The tympanic bullae are very large and elongated, their antero-internal border nearly, or actually in contact with the pterygoids. The coronoid process of each half mandible is weak; it does not exceed the height of the canine; the angular process is well developed, with a distinct outward angulation (Fig. 126).
Dentition
- Upper toothrow length (C-M3) averages 9.0 mm (8.8-9.3 mm). The single upper incisor (I2) is simple, well developed and about half the height of the canine (Fig. 126); the shaft narrows both above and below the cingulum and unlike that of T. teniotis, the simple cusp is not widely separated from its fellow. The canine is slender but well developed; it has a distinct cingulum but is without secondary cusps. The small first upper premolar (PM2) is relatively larger than that of T. teniotis and is located in the toothrow (Fig. 127); it is sometimes in contact with second upper premolar (PM4). PM4 is well developed, with a large antero-internal cusp (protocone). M1 and M2 have well defined hypocones. M3 is not greatly reduced; the metacone and three commissures are well developed and the crown area is about equal to that of PM4.
- There are two or sometimes three lower incisors (i1, i2 and i3). They are very small and bifid; their crowns are in contact with each other and with the canine; their cutting edges are distinctly below the cingulum of the tall, narrow canine. The lower premolars are normal in form and size; the first (pm2) is subequal in crown area to the second (pm4). m1 and m2 are approximately equal in size; m3 is three quarters the crown area of m2; the talonid just exceeds the trigonid in size.