Chelaseius Muma & Denmark, 1968

Kolodochka, L. A., 2024, Predatory Mites (Phytoseiidae, Parasitiformes) Of The Fauna Of Ukraine: Redescriptions Of The Species Of Amblyseiella And Chelaseius, With Resurrection Of The Genus Status For Amblyseiulus, Zoodiversity 58 (2), pp. 103-128 : 107

Genus Chelaseius Muma & Denmark, 1968

Chelaseius Muma & Denmark, 1968: 232 ; Karg, 1993: 174;

Chelaseius (Chelaseius) Denmark & Kolodochka, 1990: 219;

Chelaseius (Pontoseius) Kolodochka & Denmark in Denmark & Kolodochka, 1990: 232.

T y p e s p e c i e s: Amblyseius floridanus Muma, 1955: 264 .

Diagnosis. Dorsal side of body of female with 19 pairs of setae: AD1, AD2, AD3, AD4; PD2, PD4; AM1, AM2; AL1, AL3, AL4; PL1, PL2, PL3, PM1, PM3, PM4 on the dorsal shield; AS, PS — on the interscutal membrane. Dorsal setae contrastingly different in length. Dorsal shield well sclerotized, smooth; anterolateral margins may have oblique striation or weak reticulate sculpture; carries up to 7 pairs of solenostomes (it, iv, id, il, isc, is, ic; missing in some species id and isc). Dorsal setae differ sharply in length from microchaetae to elongated and whip-like (more frequently AL4, PM3, PM4). Perithremes long, with chaetoids. Ventrianal shield entire, with 3 pairs of preanal setae. Anal pores are present. Legs I–IV bear macrochaetes differing in degree of development. Gnathobase wide, pedipalps thickened, chelicerae massive in relation to body size, Dm without teeth, Df in various species with 2–7 large teeth, which may be well-defined or smoothed; pilus dentilis is noticeably displaced proximally.

According to the characteristics of the setae pattern, genus Chelaseius is closest to the genus Amblyseius Berlese sensu Muma et Denmark, 1968 as well Amblyseiulus Muma, 1961 , differing from both in hypertrophied chelicerae with Df longer than Dm. It differs from the genus Amblyseiulus in the presence/absence of a pair of dorsocentral setae PD2.

The structure and distribution of the genus. There are 12 known species with worldwide distribution. The vast majority of species have been recorded in the Nearctic of the Neotropical Region, the Oriental Region, the Ethiopian Region, and the Australian Region ( Demite et al., 2023), one is known in Ukraine.

Subgenus Chelaseius s. str.

Representatives of the nominative subgenus have not been recorded in the Ukraine yet.

Subgenus Pontoseius Kolodochka & Denmark

Chelaseius (Pontoseius) Kolodochka & Denmark in: Denmark & Kolodochka, 1990: 232. T y p e s p e c i e s: Chelaseius valliculosus Kolodochka, 1987: 773 .

The monotypic subgenus Pontoseius Denmark et Kolodochka, 1990 was established for the species Chelaseius valliculosus Kolodochka, 1987 on the basis of differences in the structure of chelicerae, which in mites of the subgenus have straightened, blunt immobile fingers with smoothed, poorly pronounced teeth, while in all species of the nominative subgenus Df long, curved, pointed, with large sharp teeth ( Denmark & Kolodochka, 1990). In addition, the dorsal shield of the type species of the genus, Amblyseius floridanus Muma , has 7 pairs of solenostomes, while C. valliculosus — only 5 pairs (id and il absent).