Hexaxonopsis (Hexaxonopsis) angkoriensis, 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 : 420-422

Hexaxonopsis (Hexaxonopsis) angkoriensis n. sp.

( Figures 15E , 18 )

Type material — Holotype female, dissected and slide mounted, Cambodia, 15-35-1 Angkor , moat around the main Angkor temple, 13°24’54.0"N, 103°51’34.8"E, alt. 26 m a.s.l., depth 0.4- 0.2 m, substrate: red sand covered by detritus.

Diagnosis — (Male unknown). Dorsal shield colour indistinct; lateral margins posterior to IV-L insertions with developed triangular projection on each side of ventral shield.

Description — Female: Dorsal and ventral shields lightly fused anteriorly; dorsal shield with six pairs of small glandularia (the sixth pair inconspicuous, flanking the excretory pore); postocularia well distanced from anterior margin; excretory pore projecting, located at the posterior end of dorsal shield ( Figure 18A ); dorsal shield colour indistinct ( Figure 18E ); eye pigment well developed. Ventral shield oval, slightly truncate at anterior end, lateral margins with well developed triangular projection on each side ( Figure 18B ) posterior to IV-L insertions. Lateral margins of Cx-I/II with several, blunt and posteriorly-directed projections; two pairs of glandularia (posterior one visible as a pair of distinct pores and could be interpreted as the remnants of a second pair of glandularia) located between insertions of the IV-L and genital field. Genital field with three pairs of Ac, arranged in an arc. Palp: ventral margin of P-2 convex, distal margin of P- 3 with well developed hyaline extensions, middle of ventral side of P-4 expanded, bearing relatively long and heavy seta ( Figure 18 C-D). Legs: numbers of swimming setae: II-L-5, 2; III-L-4, 2; III-L-5, 3; IV- L-4, 2; IV-L-5, 3.

Measurements — Dorsal shield L/W 440/320, ratio 1.38; ventral shield L/W 434/378; gnathosomal bay L 110; distance between most lateral pair of Ac 174, gonopore W 77. Palp: total L 214, dL/H, dL/H ratio: P-1, 35/15, 2.3; P-2, 49/39, 1.26; P-3, 26/25, 1.03; P-4, 73/25, 2.9; P-5, 31/10, 3.1; dL ratio P-2/P-4, 0.67; gnathosoma vL 56, with apodemes 91. Legs: dL of I-L: 35, 39, 34, 51, 72, 70; dL of IV-L: 45, 70, 59, 74, 82, 84.

Male: Unknown.

Etymology — Named after the country where the new species was collected.

Remarks — The new species resembles Hexaxonopsis bharatensis Cook, 1967 from India, due to the absence of a longitudinal ridge posterior to IV-L insertions, the lack of posteriorly-directed denticles on the dorsal shield and the similar morphology of palp. The latter species can be distinguished from A. angkoriensis n. sp. by the lacking projections on the lateral margin of the ventral shield, the sharppointed hook-like extensions of the coxae and the characteristic colour pattern of the dorsum consisting of a central elongated blue patch ( Cook 1967).

Distribution — Laos; known only from the locus typicus ( Figure 25D ).

Figures

FIGURE 15: Photoghraphs of dorsal shield. A-B Hexaxonopsis laosensis n. sp.: A – male holotype; B – female paratype. C-D H. cambodiensis n. sp.: A – male holotype; B – female paratype. E – H. angkoriensis n. sp., female holotype.

FIGURE 18: Hexaxonopsis (Hexaxonopsis) angkoriensis n. sp., male, Angkor, Cambodia: A – dorsal shield; B – ventral shield (arrow showing the projection on the lateral margin of the ventral shield); C – palp; D – palp (P-1 lacking); E – gnathosoma; F – I-L-4-6; G – II-L claw. Scale bars – 100 µm.

FIGURE 25: Photoghraphs of sampling sites: A – Laos, Kauangxi Waterfall (locus typicus of Monatractides laosensis n. sp., Hexaxonopsis laosensis n. sp., Sinaxonopsis laosensis n. sp. and Africasia purpurea n. sp.); B – Laos, Kouangxi Waterfall, pond behind artifical barrier (sampling site of Hygrobates hamatus K. Viets, 1935, H. henni Wiles, 2004 and locus typicus of Forelia gereckei n. sp.); C – Vietnam, Bach MAE National Park, brook with a pool (sampling site of Monatarctides sp. and locus typicus of Limnesia scharfi n. sp., Schwoerbelia pioniformis n. sp. and Arrenurus contortus n. sp.; D – Cambodia, moat around the main Angkor temple (locus typicus of Hexaxonopsis