(Geoffroy, E., 1813)
Diadem Leaf-nosed bat
External characters (Table 53)
This is a large species with a forearm length of 80-96 mm in Thailand. However, the local subspecies H. d. nicobarensis is considerably smaller with an average forearm length of 62.2 mm (58.8-64.2 mm). The ears are of moderate size, broad at the base and acutely pointed. The noseleaf is well developed, with four lateral supplementary leaflets; the fourth is small, it may be rudimentary or even absent. The anterior leaf has no median emargination and the internarial septum is not inflated. The narial lappets are well developed. The intermediate leaf is expanded with a prominent median projection which is flanked laterally by two much smaller ones. The posterior leaf is tall, thick and fleshy; it is comparable in morphology to that of H. lankadiva . There is no frontal sac. The hairs on the back are tricolored, dark brown at the base, centrally grey and tipped with brown (Hdi1). The hairs on the belly have a slightly paler appearance. Those on the upper chest and throat are grey-white throughout their length (Hill, 1967).
Cranial characters
The skull (Hdi2) of H. d. nicobarensis has an average condylo-canine length of 22.7 (22.6-22.9 mm). The rostrum is relatively broader than that of H. lankadiva . Unlike H. armiger, it is not conspicuously flattened and there is a shallow frontal depression. The anterior border of the broad mesopterygoid space is U-shaped or slightly V-shaped with the vomer projecting only very slightly beyond the posterior edge of the palate.
Dentition
Upper toothrow length (C-M3) averages 9.9 mm (9.7-10.0 mm). It is essentially similar to that of H. lankadiva ; however the difference in crown area between the larger lower second incisor (i2) and the smaller first incisor (i1) is not so marked (Fig. 100).
Variation
Specimens from Nicobar Islands are referred to H. d. nicobarensis on account of their smaller size (Hill, 1963c). Forearm length was given as 2.6" (66.3 mm) by Dobson, 1878.