Rhinolophus stheno, Andersen, 1905

Andersen, Knud, 1905, On some Bats of the Genus Rhinolophus, with Remarks on their Mutual Affinities, and Descriptions of Twenty-six new Forms., Proceedings of the Zoological Society of London 2, pp. 75-145 : 91-93

10. Rhinolophus stheno , sp. n.

(Plate III. fig. 8, a. b.)

Diagnosis. Allied to Rh. borneensis ,anterior nasal swellings much more projecting. Lower leg long: 19'8-20'8 mm. Tail extremely short: 15'5-17'8 mm. Slightly larger than borneensis : forearm 45'2-48 mm.

Details. This is a third modification of the borneensis type, in several respects recalling Rh. nereis , in others quite peculiar. The shape of the facial portion of the skull is unique within the present group. As in Rh. nereis , III.2 is lengthened, IV.L shortened: 7 « the tail is extremely c short. The general size of the animal is slightly increased. Plagiopatagium inserted 1-3 mm. above the ankle-joint.

Colour. ♂ ad., Penang; teeth unworn; skin.—General im­ pression: reddish brown above; under side much lighter, con­ trasting with the upper side. “ Mars-brown " above; base of _ hairs c? light “ drab; under side almost tl broccoli-brown. — Three spirit-specimens (Selangor; teeth unworn) apparently agree in colour with the skin.

Skull (three individuals). Owing to the much more projecting anterior nasals wellings, the skull of Rh. stheno , in side view, is strikingly different from that of Rh. borneensis . This peculiarity

in its outline is produced, not by a heightening of the anterior swellings, but by a reduction of the posterior pair; these latter, which in all the allied species form a sort of transition between the anterior swellings and the adjacent part of the supraorbital crests and interorbital constriction, are in stheno so much reduced as to leave the anterior swellings more isolated, i. e., more abruptly projecting.

Dentition. p3 external; p „ and p4 in contact; p2 in row, cusp extremely small.

Measurements. Below.

Type. ♂ ad. (in alcohol). Selangor, Malay Peninsula. Presented by H. N. Ridley, Esq. . Brit. Mus. no. 98.3.13.1.

Distribution. Selangor; Penang.

Remarks. Rh. stheno differs from Rh. borneensis in the series of characters pointed out above. From Rh. nereis , in the shape of the facial portion of the skull, the much slenderer brain-case, and the shorter tooth-rows. From Rh. rouXi , in the shape of the facial portion of the skull; the much shorter metacarpals (although the forearm is of the same length as in smaller individuals of rouXi ); the long III.2 (compared with III.1); the short IV.1

(compared with the fourth metacarpal); the excessively short tail; and the smaller hind foot.

Phylogenetically, Rh. stheno is evidently more closely connected with Rh. nereis than with any other hitherto known Bat. To call the resemblance between these two species (in III.2, IV.1, the tail) “ convergence, ” would be a phrase only, not an explanation. There can scarcely be any doubt that the type of Rhinolophus to which the now existing Rh. borneensis belongs, sent off a branch westwards; a part of this branch, isolated on the Anambas Islands, developed into Rh. nereis ; another part, in the Malay Peninsula, into Rh. stheno (cf. the diagram on p. 120).