Ptomaphaminus nanus Schilthuizen & Perreau

Schilthuizen, Menno, Perreau, Michel & Njunjic, Iva, 2018, A review of the Cholevinae from the island of Borneo (Coleoptera, Leiodidae), ZooKeys 777, pp. 57-108 : 85-87

Ptomaphaminus nanus Schilthuizen & Perreau sp. n. Figures 12 m–n, 13 t–u

Material.

Holotype: Malaysia, Sarawak, 4th Division, Gunung Mulu National Park, mixed dipterocarp forest litter, v–viii.1978 (leg. P.M. Hammond & J.E. Marshall, in NHMUK, B.M.1978-49), 1 male. Paratypes: Sarawak. Gunung Mulu National Park, 4.5.78 Tps 7-13, v–viii.1978 (leg. P.M. Hammond & J.E. Marshall, NHMUK, B.M.1978-49), 7 males, 4 females; Gunung Mulu National Park, mixed dipterocarp forest litter, v–viii.1978 (leg. P.M. Hammond & J.E. Marshall, NHMUK, B.M.1978-49), 2 males; Gunung Mulu National Park, limestone 6.4, 650 m, tp 110, v–viii.1978 (leg. P. E. Hammond & J. E. Marshall, B. M. 1978-49, NHMUK), 1 female.

Description.

Length: 1.28-1.50 mm. General colour brown; tarsi, antenna, mouthparts yellowish. Winged. Eyes well developed. Pronotum1.6 times as wide as long. Elytra 1.2 times as long as wide. Elytral internal angle rounded in male and in female, without noticeable sexual dimorphism. Male protarsi 0.6 times as wide as the protibia. Spiculum gastrale of the male genital segment dilated into a narrow spatula (Figure 13t). Aedeagus approximately 4.7 times smaller than the body length, slightly arcuate in lateral view and the sides slightly arcuate in dorsal view, the apex with a short ventrally deflexed hook (Figures 12m, 2n). Internal stylus of the endophallus long and nearly straight. On each side one lateroventral preapical seta, one lateroapical, and one seta located at the apical third of the length of the aedeagus. The lateroapical seta is pointing forward, the other orthogonally to the plane of the aedeagus. In addition, there are two very strong preapical setae on each side, which have no equivalent in other species. Female genital segment with reduced gonocoxites. Spermiduct helical with a very large number of tightly compacted coils. Apex of the spermatheca rounded, without apical sclerotised plate (Figure 13u).

Differential diagnosis.

Small-sized species with normally developed eyes and non-spiniform female elytra. Spermiduct tightly coiled; aedeagus small; distinguishable from P. marshalli , which has an equally small aedeagus, by the very short hook.

Habitat and distribution.

Known from lowland forests of Gunung Mulu, Sarawak, Malaysia.

Remarks.

A very small species, one of the smallest species of the genus.

Etymology.

Named for its very small size ( nanus = dwarf).