Halacarus longiunguis Police, 1909

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 longiunguis Police, 1909

Halacarus longiunguis: Police (1909: 116–121, figs 27–31) ; Bartsch (2007a: 394–397, figs 1–15).

Diagnosis. Length of female 572–720 µm, of male 515–559 µm (620 µm according to Police, 1919). Epicuticular ornamentation on dorsal plates delicately reticulate, on striated integument maze-like. Frontal spine long and slen- der; length of spine half that of AD and 0.2 times that of idiosoma. Pair of glp-1 at 0.7. Posterior part of AD (posterior to glp-1) shorter than anterior part, narrowed, linguiform. Pair of ds-1 level with glp-1. Corneae and ocular plates absent. Pair of canaliculi in striated integument lateral to glp-3. Pair of ds-5 immediately adjacent to glp-4 and ds-6 adjacent to glp-5. Female GA large and extending almost to level of pair of pgs-1. Ovipositor extending slightly beyond GO. Pair of pgs-1 adjacent to GA and level with posterior seta on PE. Male GA widest in anterior half; its anterior margin reaching anteriad just beyond level of posterior seta on PE. One pair of pgs immediately anterior to GA, about 105 pgs around GO.

Gnathosoma about 2.2 times longer than wide. Rostrum slightly longer than gnathosomal base and extending just beyond end of P-2. Basal seta on P-2 at 0.6. Spine on P-3 short, with blunt tip. Legs long and slender; leg IV longer than leg I and distinctly longer than idiosoma. 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 on telofemur I at 0.3. Tibiae I to IV each with four bristle-like ventral setae; distalmost ventromedial seta of tibia II delicately bipectinate. Ventromedial seta on genu II smooth. Tarsi I to IV with 2, 4, 4, 3 ventral setae. Tarsi III and IV with four and three dorsal setae, respectively. Paired claws I with delicate accessory process. Paired claws on tarsi II to IV very long and slender, without accessory process.

Remarks. Easily identified on the basis of the long legs and very slender claws, females also because of the large GA that extends to the level of pgs-1.

Distribution and ecology. Mediterranean. Expected to colonize the surface of soft ooze in the sublittoral. Records are from about 100 m depth.