Xenoseius Lindquist & Evans

De Moraes, Gilberto J., Britto, Erika P. J., Mineiro, Jefferson L. De C. & Halliday, Bruce, 2016, Catalogue of the mite families Ascidae Voigts & Oudemans, Blattisociidae Garman and Melicharidae Hirschmann (Acari: Mesostigmata), Zootaxa 4112 (1), pp. 1-299 : 30

Xenoseius Lindquist & Evans

FEMALE

Gnathosoma. Anterior margin of epistome with three denticulate projections; median projection greatly elongate, apically bifid or not. Seta h1 slightly longer than h2 and much longer than h3 and pc; insertion of h2 slightly anterior to insertion of h3. Inner palp trochanter seta elongate. Deutosternum wide, with delimiting lateral lines slightly divergent posteriorly (not distinguishable in X. yamamotoi (Ishikawa)) and seven rows of 12–20 denticles each. Corniculi about twice as long as their basal widths, with pointed tips, subparallel. Palp tarsal apotele twotined. Cheliceral digits of similar lengths, elongate; fixed digit with two teeth and apical tooth; with a long hyaline flap extending along proximal two-thirds; movable digit with two teeth in addition to apical tooth.

Idiosoma. Dorsum: podonotal and opisthonotal shields fused, ornamented, with or without lateral incisions, without transverse and nearly straight lines, delineated strip along lateral margins or posterior tubercles; anterior end of dorsal shield not strongly deflexed, but reaching anterior margin of idiosoma, with a pair of anterior protuberances. No supernumerary setae on dorsal shield or on unsclerotised lateral cuticle. Podonotal region of shield with 21–22 pairs of setae, including r3, which is similar to neighbouring setae. Opisthonotal region of shield with 14–15 pairs of setae (S2 absent in X. elizae Halliday, Walter & Lindquist ). Unsclerotised lateral cuticle with 4– 5 pairs of setae; no UR setae. Most dorsal and lateral setae of idiosoma at most as long as distance to subsequent setae, acicular and smooth, with the exception of: j1 and z1, minute and stout or palmate and strongly pilose; s1, s2 and r2, that may be minute; or J5, that may be palmate and strongly pilose. Ve n t e r: one pair or a few pairs of fragmented presternal platelets. Sternal shield with three pairs of setae of similar lengths (st1–st3) and three pairs of lyrifissures (iv1–iv3; the latter on slightly concave shield margin); st2 about equidistant to st1 and st3. Seta st4 inserted on unsclerotised cuticle. Genital shield not wide enough to include iv5 or st5 (the latter on the shield in an apparently undescribed species); slightly convex posteriorly. A pair of elongate to ellipsoidal metapodal plates. No platelets between genital and ventrianal shields. Opisthogaster with 7–10 pairs of setae in addition to circumanal setae, of which 1–3 pairs on rounded ventrianal shield; para-anal setae inserted at level of posterior margin of anal opening, about as long as or shorter than post-anal seta. Anal opening small, 1/7 to 1/8 of shield length, near shield centre. Anterior section of endopodal shield fused with sternal shield; section behind sternal shield reduced to a distinct V-shaped platelet between coxae III–IV. Exopodal shield apparently reduced to triangular platelets between coxae II–III and III–IV.

Peritreme. Extending from stigma to level of j1, almost meeting distally peritreme of opposite side; about as wide as diameter of stigma; not visible dorsally. Peritrematic shield narrow, fused with dorsal shield near z1, extending posteriorly around coxa IV and apparently not fused with exopodal shield beside coxa IV; anterior margin of peritrematic shield with a linear series of dentate ornamentation.

Legs. Leg I without pretarsus (pretarsus vestigial in X. yamamotoi ); other legs with pretarsi. Setation of legs I–IV, genu: 11 (or 12), 10, 8, 6 (or 7); tibia: 11 (or 12), 9, 7, 7. Leg II not distinctly thickened. Setae ad2 and pd2 of tarsi II–IV elongate and distally curved. With a macroseta on basitarsi of all legs.

MALE

Gnathosoma similar to female, but movable digit with one tooth in addition to apical tooth; spermatodactyl slightly longer than movable digit, slightly curved and tapering distally. Dorsal shield with ornamentation similar to female, but usually broader, including setae r5, R1, and another R series seta (probably R4); other R setae absent. Sternogenital shield with five pairs of setae (st1–st5); posteriorly truncate. Endopodal shield fused with sternogenital shield. Metapodal plates absent. Ventrianal shield subtriangular, larger than in female, bearing six of the seven pairs of opisthogastric setae in addition to circumanal setae. Legs without spine-shaped setae.