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 Simognathus Trouessart, 1889 (Figs 71–75) Type species. Pachygnathus minutus Hodge, 1863 . Adults. In both female and male GP and AP fused. Female GA with four to five pairs of pgs (rarely and unilaterally with three, exceptionally two pgs), subgenital setae lacking. Three small internal acetabula-like structures on either side of GO, situated in margin of large sacculus (Fig. 71). Ovipositor short, not extending beyond GO. Apical genital spines slender, spiniform, not sclerotized; number and arrangement not known. GO of male smaller than that of female; GA with about 10–25 pairs of pgs; of these zero to three pairs outlying, the others arranged in a ring around GO. In some species pgs setiform and smooth in others delicately plumose ( Bartsch 1994b: fig 58 ). Genital sclerites with three pairs of short sgs. Epimeral pores within epimeral vesicles. Juveniles. With deuto-, protonymph and larva, all stages with epimeral vesicles. In both deuto- and protonymph GP and AP separated. Deutonymphal GP with one (Figs 73, 74; Bartsch 1977b : fig 380) or two pairs of pgs ( Bartsch 1977b: fig 386 ); the latter close together in posterior part of GP. Deutonymphs without sgs. Genital acetabula small, two pairs present, these distinct or very small (Figs 73, 74). Protonymphal GP with zero to one pair of pgs (Figs 72, 75; Bartsch 1977b : fig. 388) but no sgs. Single pair of gac small. Remarks. Forty-four species are described ( Bartsch 2009a , 2009c ). Many of them live in sandy deposits, in beaches or sand-filled pockets amongst a macroflora and fauna. The genus is spread world-wide but more species are known from the tropical and warm-temperate south than from the north ( Bartsch 2009a ).