Thinoseius Halbert, 1920

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 : 82-83

Genus Thinoseius Halbert

Thinoseius Halbert, 1920: 126 . Type species Thinoseius berlesei Halbert 1920 (= Lasioseius fucicola Halbert 1920 ), by original designation.

Ligialaelaps Radford, 1942: 298 . Type species Ligialaelaps ewingi Pearse, 1930 , by original designation. Synonymy by Bregetova (1977a) .

Gammaridacarus Canaris, 1962: 467 . Type species Gammaridacarus brevisternalis Canaris, 1962 , by original designation. Synonymy by Evans (1963b).

Diagnosis (adults). Dorsal idiosoma. Dorsal shield and dorsal shield setae strongly sexually dimorphic. Female dorsal shield reduced, not completely covering dorsum, with 11–17 pairs of setae; male with dorsal shield covering entire dorsal idiosoma, with 30 pairs of setae. Vertex without anterior ventral extension. Dorsal setae often heterogeneous in form, some strongly modified, thick and elongate.

Ventral idiosoma. Presternal platelets absent. In female, sternal shield absent or strongly reduced to a small plate bearing 0–2 pairs of sternal setae, usually bearing only setae st1 and the first pair of pores, and setae st2–st4 with associated pores situated on soft integument; metasternal platelets absent. Male sterno-genital shield tapered posteriorly, with four pairs of sternal setae (st1–st4); st5 located on soft integument. Genital setae on or off epigynal shield; post-genital or post-sternogenital sclerites present. In female, endopodal platelets well developed, conspicuous, mostly subtriangular; endopodals I separate or fused to sternal plate; endopodals II–III and III–IV free in soft integument, separate or fused; in the male, endopodal platelets II–III fused to sterno-genital shield, endopodals III–IV fused or partly fused to the shield. Anal shield with three circumanal setae, usually subtriangular, sometimes surrounded by sclerotised opisthogastric integument giving the appearance of a ventri-anal shield. Exopodal platelets I–III absent, exopodals IV and metapodals present. Peritrematal shields free, usually developed along the posterior section of peritreme, with short post-stigmatic section; peritremes relatively long, usually with anterior end reaching to or beyond coxa I, not connected into anterolateral margins of dorsal shield. Dorsolateral and opisthogastric soft integument in female usually with more setae than the male.

Gnathosoma . Palptarsus without paired macroeupathidium; palpgenu with five setae (al 2 lacking). Cheliceral segments moderately short and stout, cheliceral digits robust (especially in deutonymphs); movable digit bidentate in female, unidentate in male; male spermatodactyl tubular, hooked or bulbed distally. Epistome produced into five or more processes, processes simple or branched, smooth or denticulated distally; median process usually longest.

Legs. Setation of legs I-II-III-IV: coxae 2-2-2-1, trochanters 5-5-5-5, femora 12-10-7-6, genua 11-10-7/8- 7 and tibiae 11-9-7-7 (see Table 3). Male legs not spurred.

Notes on the genus. The name of the type species of this genus was originally spelled as T. berlesii by Halbert (1920), and has been incorrectly spelled T. berlesei by subsequent authors. This subsequent spelling is retained here because of its prevailing usage (International Code of Zoological Nomenclature, Article 33.3.1). Halbert (1920) described the male of Lasioseius fucicola and the female of Thinoseius berlesei in the same paper, apparently having been misled by the strong sexual dimorphism that is typical of species of Thinoseius . Evans & Browning (1953) recognised the synonymy of these two species, and chose the name T. fucicola on the basis of page priority.

The subfamily classification of the Eviphididae currently places Thinoseius in the subfamily Thinoseiinae , and all other genera in the subfamily Eviphidinae . We agree with Kazemi et al. (2008) that the present subfamily structure is not useful, and it is not used here.

There are almost 20 described Thinoseius species recorded from the coasts of North America, Europe, the Middle East, Far Eastern Russia, Japan, sub-Antarctic islands, New Zealand, and Australia ( Halbert 1920; Willmann 1939; Sellnick 1940; Evans & Browning 1953; Evans 1954, 1962, 1963b, 1969; Canaris 1962; Hirschmann 1966a, 1966b; Hunter 1970; Bregetova 1977a ; Athias-Henriot 1980; Koyumdjieva 1982; Hennessey & Farrier 1988; Klimov 1998; Takaku 2000; Błaszak et al. 2004; Halliday, personal observations). Representatives of this genus are halophilous and colonise decaying seaweed and other tidal debris on sea coasts. They are frequently phoretic on some crustaceans (Amphipoda) and flies ( Coelopidae and Anthomyidae). Aditionally, Klimov (1998) found Thinoseius spinosus on carabid and staphylinid beetles and a scatophagid fly. Four species have been recorded from Europe, but none occur in Slovakia.