Thalassogamasus sidortschukae Makarova 2019, sp. nov.

Thalassogamasus sidortschukae sp. nov.

Figs 1, 4, 7–48

Material. Holotype, female: NORTH-EAST ASIA, eastern CHUKOTKA, Lawrence Bay, Mutnyi Brook mouth, 65°31’ N 170°59’ W, maritime sandy beach with Mertensia maritima, Honckenya peploides, Senecio pseudoarnica, Leymus villosissimus, 28 July 2013, O.L. Makarova (ZIRAS). Paratypes: 10 females, 2 males with same data as for holotype (ZIRAS); 1 female, with same data as for holotype (CNC); 1 male, NORTH-EAST ASIA, northern CHUKOTKA, Apapelgyn River mouth, 69°45’37”N 170°36’16”E, sandy beach, seaweed accumulations between cobblestones under a bridge footing, 21 July 2018, O.L. Makarova (CNC).

Other material: NORTH-EAST ASIA, CHUKOTKA, 11 deutonymphs, 27 protonymphs, 54 larvae, with same data as for holotype, O.L. Makarova; NORTH-EAST ASIA, MAGADAN REGION, 1 deutonymph, Tauisk surroundings, 59°44’04”N 149°23’15”E, maritime salt marsh, from the sand under Puccinellia phryganodes, July 2017, M. Bizin, B. Efeikin.

Description. Rather large yellowish mites with elongate oval idiosoma and large brownish cheliceral digits. Anterior idiosomal margin truncate, posterior margin roundish. Idiosomal shields weakly sclerotised, very finely punctate, with clearly reticulate ornamentation on nearly all surfaces except central part of podonotal shield, and with reduced peritrematal plates. Dorsal shields rather narrow, particularly opisthonotal shield; lateral soft cuticle with numerous setae. Most idiosomal setae with fine, hair-like tips. Legs of moderate length, tarsi II–IV with large blunt spines and long attenuated setae. Basitarsus IV of normal form. Ambulacrum of all legs on short pedicel. Tarsus I distally with six rod-like sensory setae.