Halacarus hemispinosus 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 : 30

Halacarus hemispinosus Newell, 1984

Halacarus hemispinosus: Newell (1984: 52–54, figs 97–102) .

Diagnosis. Length of female 766–835 µm, of male 570 µm. Frontal spine short, triangular, its length equalling 0.2 times that of AD and less than 0.1 times that of idiosoma. Posterior part of AD linguiform. Pair of glp-1 at 0.6 relative to length of AD. Pair of ds-1 distinctly posterior to glp-1. Ocular plates ovate, each with cornea and canaliculus. Pairs of ds-5 and ds-6 medial (anteromedial) to glp-4 and glp-5; both removed from gland pores by at least twice glp diameter. In female pair of pgs-1 removed from margin of GA, distance pgs-1 to GA 0.6 times that between margins of GA and GO. Anterior margin of GA broadly ovate, reaching far beyond anterior margin of GO. Ovipositor extending distinctly beyond GO. Male with pair of pgs- 1 in striated integument and 33–35 setae on either side of GO.

Gnathosoma about 2.2 times longer than wide. Rostrum longer than gnathosomal base, extending just beyond end of P-2. Basal seta of P-2 at 0.6. Seta on P-3 spiniform, blunt. Integument of legs punctate. Telofemur, genu and tibia I with 2, 2, 4 tapering ventral spines. Heavy seta on telofemur I at 0.3. Trochanters I to IV with 1, 1, 3, 1 setae, basifemora I to IV with 2, 3, 2, 2 setae. Ventromedial setae on tibia II and that seta on genu II bipectinate. Tarsi I to IV with 2, 1, 1, 1 ventral setae, respectively. Tarsi III and IV with four and three dorsal setae, respectively. Paired claws of all tarsi with accessory process but no pecten.

Remarks. Halacarus hemispinosus can be identified on the basis of the short, triangular frontal spine and the position of the pair of canaliculi on the ocular plates.

Distribution and ecology. Near Macquarie Island, at about 54°30’S, 159°00’E and a depth of 88– 278 m.