Eudiscoderma gen. nov.

Disc-nosed bat

Figures 1–11; Tables 1–2

Type species. Eudiscoderma thongareeae sp. nov.

Etymology. The genus name is derived from the well-defined disc-shaped noseleaf of the type species. The genus gender is neuter.

Diagnosis. Eudiscoderma has the following unique combination of characters, which discriminates it from all other currently described genera in the family Megadermatidae (Table 1).

In the upper dentition, the first upper premolar (P2) is absent. Therefore, the dental formula is i 0/2, c 1/1, p 1/ 2, m 3/3 = 26. The upper canine is greatly enlarged, almost twice the crown area of the upper premolar (P4) (Figs. 4, 5 b), and more than twice the height (Fig. 6 b); it is without a discrete anterolingual cingular cusp but has a large posterior accessory cusp, which is attached for most of its length to the main cusp and is about equal in height to the upper premolar (P4). In the first upper molar (M1), the preparacrista is subequal in length to the postmetacrista, which is not elongated; the mesostyles of both M1 and M2 are well developed; the mesostyle of M1 is situated labially as both the postparacrista and premetacrista are not shortened (Fig. 7).

In the lower dentition, the canine (C1) has a well defined cingulum but is without an anterolingual cingular cusp. The first premolar (P2) is noticeably large and rounded, equal to or exceeding, the crown area of the more rectangular second lower premolar (P4) (Figs. 4, 5 b). In the first and second molars (M1 and M2), the crown area of the talonid is about two-thirds that of the trigonid (Fig. 7 b).

In the skull, the rostrum has a pronounced depression but is without an expanded frontal shield or preorbital or postorbital processes (Fig. 8 b). The sagittal crest is well developed. The coronoid process of each half mandible is greatly enlarged (Fig. 6 b).

The baculum is Y-shaped with two small but distinct prongs, which represent about 25% of the baculum length, which is 2.1 mm (Fig. 9 b). The shaft is slightly curved and there is a depression on its ventral surface.

In external morphology, the posterior noseleaf is relatively short, erect and rounded; the longitudinal ridge is slightly convex in the mid-part and with a heart-shaped base; it resembles a ‘down arrow’; the anterior noseleaf is similar in width to the posterior noseleaf but is shorter (Fig. 1 b). In the interfemoral membrane, the principal blood vessel that runs from each ankle merges with the middle vertical vessel some 15 mm below the anus (Fig. 1 a).

As the genus is believed to be monotypic, the description below may serve for both genus and species.