Halacarus discophorus Bartsch, 1993

Bartsch, Ilse, 2011, Halacarus socius (Acari: Halacaridae), description of the male and diagnoses of species of the Halacarus actenos group, Zootaxa 2800, pp. 18-40 : 27

Halacarus discophorus Bartsch, 1993

Halacarus discophorus: Bartsch (1993b : 50–53, figs 3A–G, 4A–D; 2009b: 188, figs 59–64); Otto (2001: 695–696, fig. 6).

Diagnosis. Length of female 675 µm, of male 470–641 µm. Epicuticula on plates and legs delicately reticulate. Frontal spine slender, medium-sized, 0.3 times of length of AD and 0.1 times of that of idiosoma. Posterior part of AD slender, triangular. Pair of glp-1 at 0.6 relative to length of AD; pair of ds-1 immediately anterior to glp-1. Ocular plates small, ovate, each plate almost completely covered by cornea. Canaliculi in striated integument posterolateral to OC. Pairs of ds-5 and ds-6 adjacent to glp-4 and glp-5, respectively, sharing the sclerites. Male with pair of small platelets in striated integument between ds-5 and ds-6, in female no such platelets present. Female GA short, anterior margin straigth to slightly excavate. Pair of pgs-1 slightly posterior to level of end of PE; distance to anterior margin of GA equalling 2.8 times interval between margins of GA and GO. Male GA rounded. With one pair of pgs anterior to GA and 66 setae around GO.

Gnathosoma about twice as long as wide. Rostrum longer than gnathosomal base and reaching to end of P-3. Basal seta on P-2 at 0.6. Trochanters I to IV with 1, 1, 2, 1 setae, basifemora I to IV with 2, 4, 2, 2 setae. Telofemur, genu and tibia I with 2, 2, 4 spiniform ventral setae. Basalmost ventral spine at 0.2. Both ventromedial setae on tibia II and that seta on genu II distinctly bipectinate. Tarsi I to IV with 2, 2, 2–4, 3 ventral setae, tarsi III and IV with four and three dorsal setae. Accessory processes on paired claws with delicate tines.

Remarks. Males can be identified because of the pair of platelets between the ds-5 and ds-6. Females have a GA with an unusual straight or slightly concave anterior margin.

Distribution and ecology. South China Sea ( Singapore), eastern Indian Ocean (Rottnest and Monte Bello Islands, Australia) and western Pacific Ocean (Great Barrier Reef, Australia). Most findings are from coarse or gravelly shallow water sediments.