Halacarus echinatus Newell, 1984

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 : 27-28

Halacarus echinatus Newell, 1984

Halacarus echinatus: Newell (1984: 50–52, figs 89–96) .

Diagnosis. Length of female 861 µm, of male 696 µm. Frontal spine long and slender, its length equalling 0.5 and 0.2 times that of length of AD and idiosoma, respectively; spine extending beyond level of P-3. Part of AD posterior to gland pores short, triangular. Pair of glp-1 at 0.8 relative to length of AD. Pair of ds-1 posterior to level of glp-1. Ocular plates triangular, with cornea; canaliculus in posterior margin of plate. Pairs of ds-5 and ds-6 medial to glp-4 and glp-5, respectively, both distinctly removed from gland pores. Female GA in posterior end of idiosoma, at 0.8 relative to length of idiosoma; anterior margin of GA widely rounded. Pair of pgs-1 posterior to level of insertion of leg IV and well anterior to GA. Interval between pair of pgs-1 and margin of GA 0.8 times of that between anterior margins of GA and GO. GO in posterior part of GA. In male anterior pair of pgs immediately anterior to GA. GO in middle of GA, surrounded by about 100 pgs.

Gnathosoma 2.4 times longer than wide. Rostrum distinctly longer than gnathosomal base, extending anteriad beyond level of end of P-3. Basal seta on P-2 at 0.7. Spine on P-3 pointed and as long as that segment. Integument of legs punctate. Telofemur, genu and tibia I with 2, 2, 4 spiniform ventral setae. Trochanters I to IV with 1, 1, 3, 1 setae, basifemora I to IV with 2, 3, 2, 1 setae. Both ventromedial setae of tibia II bipectinate; distal seta much longer than basal seta. Tarsi I to IV with 2, 1, 1, 1 ventral setae. Tarsi III and IV with four and three dorsal setae. Paired claws long and slender, with delicate accessory process but without pecten.

Remarks. Halacarus echinatus can be recognized on the basis of the combination: long and slender frontal spine, posterior part of AD triangular, OC triangular, tarsi II to IV with 2, 1, 1, ventral setae.

Distribution and ecology. Southern Argentina, Chile and southeast Pacific, at depth of 40 to 485 m.