Schwoerbelia, Pešic & Smit, 2016

Pešic, V. & Smit, H., 2016, New records of water mites from Southeast Asia (Acari: Hydrachnidia) with the description of two new genera and 12 new species, Acarologia 56 (3), pp. 393-433 : 409-410

Family Pionidae Thor, 1900 Genus Schwoerbelia n. gen.

Diagnosis — Female (Male unknown): Character states of family Pionidae (see Cook 1974). Dorsum soft. All coxal setae slender, not spatulate; medial margin of Cx-III almost as long as medial margin of Cx-IV, posterior margin of Cx-IV concave, without angular projections. Genital bay very shallow, gonopore very long, genital plates broad and rounded, much smaller than gonopore, with 5 pairs of acetabula. P-3 with a very long lateral seta, P-4 with a peg-like mediodistal seta, ventral setae not associated with tubercles ( Figures 11 B-C); gnathosoma with posterior anchoral process. Legs slender, swimming setae present.

Type species — Schwoerbelia pioniformis n. sp.

Etymology — The genus name is in honour of Jürgen Schwoerbel (1930-2002), who described one of the pionid subfamilies. Moreover, he was one of

Peši´c V. and Smit H.

the editors of a new standard work on European water mites, published in the series "Süsswasserfauna von Mitteleuropa".

Remarks — Due to the following characters: medial margin of posterior coxal plates formed jointly by Cx-III and Cx-IV, all setae on Cx-II and -III fine, not thickened, gnathosoma ventral margin posteriorly projecting in an anchoral process (in ventral view bifurcate as in Figure 11D ), and P-4 with a distoventral peg-like seta, the female of new species resembles to those of genus Piona . However the single female from a stream in Vietnam is unique in P- 3 with a very long lateral seta, exceeding the tip of P-5. In all known members of subfamily Pioninae Thor lateral setae on P-3 are short. The new genus resembles Huitfeldtiinae (P-3 with a very long lateral seta) which in addition to Huitfeldtia Thor, 1900 (Holarctic) , includes Larri Harvey, 1996 ( Australia) and Gereckea Smith & Cook, 2009 ( Canada) . The new genus differs in slender, not spatulate coxal setae (present in Huitfeldtia ), posterior margin concave, without acute-angled apodemes, and a small peg, not a prominent spine-like mediodistal seta on P-4 (see Smith et al. 2015). In most pionid groups, characters (sexual dimorphism on leg segments) important for classification are restricted to males. However the unique features of female from Vietnam are large enough to warrant the erection of the new genus.

Figures

FIGURE 11: Schwoerbelia pioniformis n. gen., n. sp., female, Bach MAE National Park, Vietnam: A – idiosoma, ventral view; B-C – palp; D – gnathosoma; E – I-L-5 and -6; F – IV-L. Scale bars – 100 µm.