Sinaxonopsis siamicus, Smit, 2016

Smit, H., 2016, The water mite family Aturidae Thor, 1900 from Southeast Asia (Acari: Hydrachnidia) with the description of one new genus and 14 new species, Acarologia 56 (3), pp. 341-365 : 360-362

Sinaxonopsis siamicus n. sp.

( Figure 14 )

Material examined — Holotype female, Stream near Haewsai Waterfall, Nam Nao NP, Thailand, 16°40.668N 101°41.856E, alt. 425 m a.s.l., 16-xi-2007.

Diagnosis — Ridge anterolaterally of fourth leg sockets very short; setae associated with dgl-2 and dgl-3 distanced from glandularia; lgl-2 not on large posterior dorsal shield, lgl-3 and -4 on small humps.

Description — Female: Idiosoma colourless, dorsally 429 long and 389 wide, ventrally 429 long. Dorsum with three plates, smaller paired anterior plates and a large unpaired posterior plate. Anterior plates with the postocularia and two pairs of glandularia, posterior plate with five pairs of glandularia. Setae associated with dgl-2 and dgl-3 distanced from glandularia. This large posterior pair fused to ventral shield, but most of the posterior part of the dorsal furrow not visible due to rugosity of the idiosoma. Suture lines of coxae incomplete, first coxae not extending beyond anterior idiosoma margin, posterior margin of fourth coxae incomplete. Cxgl-4 lying posterior to fourth leg sockets. Excretory pore posterior to genital field but visible only in dorsal view. Gonopore relatively large, 102 long. Genital field with approximately 20 pairs of acetabula on indistinct genital plates, but due to rugosity of idiosoma most of these not visible in ventral view. Length of P1-5: 35, 64, 32, 84, 36. Length of I-leg-4-6: 80, 84, 78. Length of IV-leg-4-6: 98, 116, 96. Legs without modifications, IV-leg segments slender. Swimming setae: II-leg-4 one, II-leg- 5 three, III-leg-4 one, III-leg-5 three, IV-leg-4 with one swimming seta and IV-leg-5 with two swimming setae.

Etymology — Named after the old name of Thailand.

Remarks — The new species differs from S. unicucrus Yi and Jin, 2012 in the smaller size (564 – 594 for S. unicucrus ), A2 posteromedially of dgl-1 (A2 anteromedially of dgl- 1 in S. unicucrus ) and the characters mentioned in the diagnosis of the new species. Yi and Jin (2012) placed the new genus tentatively in the Axonopsinae , which is a correct placement in my opinion.

Figures

FIGURE 14: Sinaxonopsis siamicus n. sp., holotype female: A – dorsum; B – venter; C – palp; D – IV-leg-4-6. Scale bars = 50 µm.