Hygrobates (Hygrobates) hamatus K. Viets, 1935

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 : 403

Hygrobates (Hygrobates) hamatus K. Viets, 1935

( Figure 6 )

Material examined — Laos, 15-32-1, Kouangxi Waterfall, pond behind artificial barrier within a branch near the main brook, 19°44’56"N, 101°59’33"E, alt. c. 490 m a.s.l., water depth 0.4 m, substrate: travertine mud covered by a thick layer of leaves, 21.iv.2015, 0/1/0 (mounted) .

Morphology — Female: Integument striated; posteromedial margin of Cx-I straight; apodemes of Cx-II forming an acute angle; Cx-IV subtriangular in shape, with anterior and posterior margins converging to median line, posteromedial margin with a well protruding apodeme ( Figure 6A ). Acetabula in in a triangular arrangement, medial margin of genital plate indented in the centre. P-2 ventral margin weakly concave, distally forming a right angle, denticles covering distal 2/3 of P-3 ventral margins, P-4 ventral setae on the same level ( Figure 6C ). Swimming hairs absent.

Measurements — Idiosoma L/W 844/638; genital field L/W 153/187, genital plate L 114 – 116. Palp: total L 427, dL/H, dL/H ratio: P-1, 23/35, 0.67; P-2, 118/73, 1.62; P-3, 95/69, 1.39; P-4, 155/28, 5.5; P-5, 36/12, 3.1; L ratio P-2/P-4, 0.76. Legs: dL of I-L: 63, 103, 133, 173, 178, 159; dL of IV-L: 166, 150, 221, 266, 311, 241.

Remarks — The single female from Vietnam fits the original description of Hygrobates hamatus K. Viets, 1935 from Sumatra and Java ( Viets 1935), but it is noticeable larger.

Distribution — A widespread species, known from India to Australia.

Figures

FIGURE 6: Hygrobates (Hygrobates) hamatus K. Viets, 1935, male, Kauangxi Waterfall, Laos: A – coxal and genital field; B – I-L-5 and -6; C – palp. Scale bars – 100 µm.