Crassicheles Karg, 1963

Mašán, Peter & Halliday, Bruce, 2010, Review of the European genera of Eviphididae (Acari: Mesostigmata) and the species occurring in Slovakia 2585, Zootaxa 2585, pp. 1-122 : 45-47

Genus Crassicheles Karg

Crassicheles Karg, 1963: 276 . Type species Iphidoides concentricus Oudemans, 1904 (= Uroiphis striatus Berlese, 1903 ), by original designation.

Diagnosis (adults). Dorsal idiosoma. Female idiosoma subglobular, almost hemispherical, subcircular in outline, very weakly sclerotised, smooth and transparent ( Fig. 50). Male dorso-ventrally flattened, oval and well sclerotised ( Fig. 61). Vertex flat and poorly developed. Female dorsal shield absent, represented only by small anteromedial oval-shaped area of slightly darker sclerotisation, this area with a row of microdenticles on its posterior margin; dorsal setae moderately heterogeneous in length and form, anteromedial setae short and fine; other dorsal setae moderately to distinctly longer, thread-like or needle-like; vertical setae j1 relatively short and inserted close to anterior margin. Male dorsal shield well developed and sclerotised ( Fig. 61), entire, suboval, completely covering dorsal idiosoma, fused to anterior sections of peritrematal shields anterolaterally, with 30 pairs of setae, dorsal shield setae short, needle-like, except longer vertical setae j1 and shortened J5 subequal in length; z1 with ventral position on vertex ( Fig. 62). In female, striate soft integument not developed on surface. Pore-like structures small and subcircular; in females three pairs of pores markedly enlarged.

Ventral idiosoma ( Fig. 56). Presternal platelets absent. In female, most of ventral surface very weakly sclerotised, smooth and transparent. Sternal area without a distinct shield, bearing three pairs of setae and two pairs of pores ( Fig. 59). Sternal setae st1–st3 short, relatively thick, thorn-like, subequal in length and each inserted on low protrusion. Genital region more sclerotised, with a pair of metasternal platelets and distinct epigynal shield. Each metasternal platelet with short thorn-like seta and adjacent pore. Epigynal shield relatively small, narrow, rounded posteriorly and bearing a pair of short thorn-like setae; its anterior part is associated with widely formed hyaline margin medially produced into acute point; genital pores not visible. Male sterno-genital shield with four pairs of sternal setae, fused with endopodal platelets II–III; endopodal platelets III–IV separate, not fused to sterno-genital shield, exopodals IV present, metapodals absent. In female, endopodal and exopodal platelets absent; metapodal platelets indistinct. Peritremes well developed and reaching coxae of legs II; peritrematal shields absent in female, well developed in male, with very short post-stigmatic section. Post-genital or post-sternogenital sclerites absent. Anal shield indistinct or absent in female, well sclerotised and subtriangular in male; three needle-like circum-anal setae present; cribrum well developed. Lateral and opisthogastric integument with ten pairs of setae in female, seven pairs in male (excluding st5, situated on soft integument between coxae IV).

Gnathosoma . Palptarsus without paired macroeupathidia. Cheliceral segments moderately short and stout, cheliceral digits relatively robust (especially in deutonymphs); movable digit with two subdistal teeth in female ( Fig. 52), with one robust subdistal tooth in male. Male with short club-like spermatodactyl, directed sideways. Epistome with widened, straight or roof-like base, produced into massive central projection and two to four shorter lateral spines on each side of the projection; projection lanceolate, spinate basally and barbed distally ( Figs 54, 55, 60).

Legs. Setation of legs I-II-III-IV: coxae 2-2-2-1, trochanters 6-5-5-5, femora 13-10/11-6-6, genua 11-10- 8-7 and tibiae 11-9-7-7 ( Table 3). In female, lateral lobes of pulvillus on legs II–IV modified, elongated and distally pointed, projecting beyond claws. Legs of male with no spur-like setae.

Notes on the genus. The genus Crassicheles was originally described by Karg (1963), on the basis of the deutonymph only, with type species Iphidoides concentricus Oudemans 1904 . We have now found that I. concentricus is a synonym of Uroiphis striatus Berlese 1903 , but we retain Crassicheles as a separate monotypic genus. In this generic concept, the genus differs from the related genera Neocrassicheles and Uroiphis by the features listed in Table 6. Three other species have been placed in Crassicheles by other authors, namely C. bacillatus ( Athias-Henriot 1980) , C. greeni Evans 1980 , and C. holsaticus ( Willmann 1937) , but we here transfer these species into Uroiphis . Crassicheles has been recorded mainly from the European continent, with a few additional records from some sites in the south-eastern Palaearctic. The only known species is phoretic on flies, and occurs in dung and other temporary deposits of rotting organic matter.