Halacarus leptopus Bartsch, 2002

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 : 31

Halacarus leptopus Bartsch, 2002

Halacarus leptopus: Bartsch (2002: 36–40, figs 28–46) .

Diagnosis. Length of female 580–653 µm, of male 562 µm. Frontal spine long and slender. Spine half length of AD and 0.2 times that of idiosoma. Posterior part of AD narrowed, linguiform. Pair of glp-1 at 0.7 relative to length of AD. Pair of ds-1 slightly anteromedial to glp-1. A pair of small corneae present but no ocular plates. Pair of canaliculi in striated integument lateral to corneae and glp-3. Pairs of ds-5 and ds-6 immediately adjacent to glp-4 and glp-5, respectively, sharing the sclerites. Female GA in posterior fifth of idiosoma; anterior margin of GA rounded. Anterior pair of pgs in female and male almost level with insertion of leg IV. In female distance from pgs- 1 to GA 1.2 times that between margins of GA and GO. Male GA ovate, extending to level of posterior end of PE. Distance between GO and anterior margin of GA equalling length of GO. Pair of pgs- 1 in striated integument close to GA; about 70 pgs arranged around GO.

Gnathosoma slender, about 2.3 times longer than wide. Rostrum longer than gnathosomal base and extending beyond P-3. Basal seta on P-2 at 0.8. Integument of legs delicately striated. Surface of legs smooth. Telofemur, genu and tibia I with 2, 2, 4 spiniform ventral setae. Basalmost ventral spine on telofemur I at 0.5. Trochanters I to IV with 1, 1, 2, 1 setae, basifemora I to IV with 2, 4, 2, 2 setae. Ventromedial seta on genu II smooth; on tibia II distalmost ventromedial seta bipectinate. Tarsi I to IV with 2, 4, 4, 4 ventral setae. Tarsi III and IV with four and three dorsal setae, respectively. Paired claws with delicate accessory process.

Remarks. The species is characterized by the very long and slender frontal spine and the two pairs of sclerites including the glp-4 and ds-5 and glp-5 and ds-6, respectively. The frontal spine is longer than in H. griseus .

Distribution and ecology. Northeastern Atlantic, Great Meteor Seamount, at 312–343 m depth.