Actacarus Schulz, 1937

Bartsch, Ilse, 2015, The genital area of Halacaridae (Acari), life stages and development of morphological characters and implication on the classification, Zootaxa 3919 (2), pp. 201-259 : 207

Actacarus Schulz, 1937

(Fig. 7)

Type species. Actacarus pygmaeus Schulz, 1937 .

Adults. GP and AP fused. Female GA with two to three (to five) pairs of smooth pgs. Subgenital setae lacking. GO in posterior part of GA. Ovipositor at rest extending beyond GO, in some species even beyond anterior margin of GA. Everted ovipositor apically with pair of slender, seta-like anterior and seven posterior genital spines. These spines setiform ( Konnerth-Ionescu 1970: pl. 1E) or dissimilar in shape, hooked and spiniform ( Bartsch 1999a: figs 18, 19; Schulz 1937: fig. 1C). Spines weakly sclerotized. Acetabula small, from almost equal- to unequal-sized, three pairs about level with mid-GO (Fig. 7; Abé 1990a: fig. 2F, 1997: fig. 4E; Newell 1984: fig. 703). GO in male slightly smaller than in female and removed from posterior margin of GA. GA with 7–18 pairs of slender, smooth pgs situated either close around GO or lateral and posterior to GO; one pair of setae outlying. Each genital sclerite with one to three sgs. GO with three pairs of small acetabula ( Abé 1997: fig. 4F). AE in both male and female without epimeral pores.

Juveniles. A larval and two nymphal stages known. Deutonymph with GP and AP partly or completely separated ( Bartsch 1977b: fig. 104; Abé 1997: fig. 4G) or fused ( Bartsch 1977b: fig. 104, 1999a: fig. 23; Abé 1990a: fig. 4B). Deutonymphal GP with two pairs of internal gac and two pairs of pgs; sgs lacking. In protonymph GP and AP fused ( Abé 1990a: fig. 5B; Bartsch 1999a: fig. 25). Protonymphal GA with single pair of internal gac; pgs and sgs not developed. Larva with large anal plate. Epimeral pores vestigial or lacking ( Bartsch 1977b: fig. 106, 1999a: fig. 27; Abé 1990a: fig. 6B).

Remarks. Actacarus species are inhabitants of sandy deposits; 24 species are known to date ( Bartsch 2009a). The genus is spread world-wide in tropical, warm- and cold-temperate regions.