Ochthebius (Aulacochthebius) plicicollis Fairmaire

O. (Aulacochthebius) plicicollis Fairmaire Figs. 2, 31 Ochthebius plicicollis Fairmaire 1898: 223. Differential diagnosis. Similar in size (ca. 1.40 mm) to O. (A.) tenuipunctus; distinguished therefrom by the longer and deeper midlongitudinal impression of the pronotum, and by the aedeagus. Discussion. Both species of Malagasy O. (Aulacochthebius), O. (A.) perlaevis (Perkins) and O. (A.) plicicollis Fairmaire, are typical species of the O. (A.) tenuipunctus Group, very smooth dorsally. The aedeagi of both species differ in the shape of the main-piece from that of other members of the group. O. (A.) plicicollis is known from only a few localities in Madagascar (Fig. 29); whereas O. (A.) perlaevis is widely distributed on the island (Fig. 32).Published as part of Perkins, Philip D., 2023, Taxonomic revision of African water beetles in the genus Ochthebius Leach (1815) subgenus Aulacochthebius Kuwert (1887) (Coleoptera: Hydraenidae), pp. 501-546 in Zootaxa 5228 (5) on page 537, DOI: 10.11646/zootaxa.5228.5.1, http://zenodo.org/record/754317