Halacarus celatus 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 : 37

Halacarus celatus Bartsch, 1993

Halacarus celatus: Bartsch (1993b: 48–50, fig. 2A–K) .

Diagnosis. Length of female 486–493 µm, of male 462 µm. Texture of epicuticula on plates fingerprint-like, on legs delicately striated and anastomosing. Frontal spine very short, cuculliform, extending beyond camerostome by about half the latter’s length. Posterior margin of AD linguiform. Pairs of ds-1 and glp- 1 in striated integument; glp-1 at 0.5; ds-1 posterior to glp-1. Ocular plates absent, pair of corneae and canaliculi in striated integument. Pairs of ds-5 and ds-6 adjacent to glp-4 and glp-5, respectively. GA of female and male rounded, in both anterior pair of pgs situated within GA. Female GA with crescentic shaped cerotegument on either side of GO, these areas slightly, but not markedly, set off from median part of GA. Female with another two pairs of widely separated setae lateral to GO. Distance between anterior margin of GA to that of GO less than half length of GO. Male with three to four pairs of outlying pgs (pair of pgs-1 included) and 23–24 pairs of setae close to GO.

Gnathosoma short, rostrum about as long as gnathosomal base and extending to end of P-3 of short palps. Basal seta on P-2 at 0.7. Epicuticula of legs striated. Trochanters I to IV with 1, 1, 2, 1 setae, basifemora I to IV with 2, 3, 2, 2 setae. Genu and tibia I with two and four tapering ventral setae, telofemur I ventrally with a bluntly ending spiniform basal seta, at 0.3, and a short, slender seta. Basifemur II with three setae. Four ventral setae on tibia II slender, none bipectinate. Tarsi I to IV with 2, 2, 2, 2 ventral setae, tarsi III and IV with four and three dorsal setae. Paired claws with accessory process and claws II and III with pectines along shaft of claws.

Remarks. The species differs in several characters from the above mentioned species of the H. actenos group, on the female GA the cerotegument anterior to the GO is reduced, the ventromedial seta on telofemur I is small, delicate, not spiniform, none of the ventral setae on tibia II is bipectinate, and the claws of tarsi II and III bear tines on the shaft. Other characters which separate this species from the others are: the frontal spine is short, obtuse, the pairs of glp-1 and ds-1 are in the striated integument, the anterior pair of pgs is on the GA in both females and males, the posteriormost pair of pgs is close to the posterior end of the female GO, the gnathosoma is short, the epicuticula of the legs striated. Because of the crescentic shaped cerotegument, the distinctly striated epicuticula, the delicate ventromedial seta on telofemur I, and the tines along the claw shaft, this species is not included in the H. actenos group.

Distribution and ecology. Indian Ocean, southwestern Australia. Extracted from coarse sand and gravel. The species is expected to be psammobiont.