The genital area of Halacaridae (Acari), life stages and development of morphological characters and implication on the classification Author Bartsch, Ilse text Zootaxa 2015 3919 2 201 259 journal article 10.11646/zootaxa.3919.2.1 8a0f71e3-5416-41c5-8e7d-b4cc574b7340 1175-5326 245246 8CB77F9E-A35E-43E2-91F7-7822AE421B33 Acanthohalacarus Bartsch, 2001 ( Figs 1 and 2 ) Type species. Acanthohalacarus reticulatus Bartsch, 2001 . Adults. Genital and anal plates fused. Female GA with five (rarely four or six) pairs of slender pgs, genital sclerites with two pairs of short sgs. Genital acetabula internal; posterior-most pair of acetabula larger and removed from two anterior pairs ( Fig. 1 ). Ovipositor at rest extending beyond anterior margin of GO. With short basal pair and slender, spiniform apical pairs of genital spines; number of spines not known. Male GO in ventral position, smaller than that of female ( Bartsch 2001a: fig. 1D ), in single species known surrounded by 45–57 slender and smooth pgs; several of pgs outlying. Genital sclerites with five pairs of short sgs, two anterior pairs setiform, three posterior ones short, spiniform. Acetabula adjacent in posterior half of GO, the three pairs short, equal-sized, cupuliform ( Fig. 2 ). Anterior epimeral plate without epimeral pores. Juveniles. One larval and two nymphal stages known. Nymphs with genital plate separated from anal plate. Deutonymphal GP with two pairs of pgs, at least one pair of minute sgs and two pairs of internal gac ( Bartsch 2001a: fig. 3B ). Protonymphal GP with single pair of gac; pgs and sgs lacking. Nymphs without but larva with pair of epimeral pores ( Bartsch 2001a: fig. 3F ). Remarks. At present a single species is known, collected on a seamount in the northeastern Atlantic Ocean ( Bartsch 2001a ).