Hygrobates henni, Wiles, 2004

Wiles, P. R., 2004, Water mites (Acari: Hydrachnidia) from South-East Asia, Thailand and Sulawesi Tenggara (Indonesia): descriptions of new species and new records, Journal of Natural History 38 (17), pp. 2153-2165 : 2157-2158

Family HYGROBATIDAE Koch, 1842 Hygrobates henni new species ( figure 3 )

Material examined. HOLOTYPE: „, slide M425„, 17 August 1988, Mai Yim waterfalls, Chaing Mai, Thailand . PARATYPE 1: M426”; PARATYPE 2: M427”.

Description. Male: body length 556, width 428. Dorsum papillose, without plates; A1 setae large. Infracapitulum length 216 (247 with secondary sclerotization). Epimera with secondary sclerotization, EpII narrow, suture line EpIII/IV short, terminating at E2; E4 located posterior to EpIV. Fused genital plates, each with three acetabula in a triangular arrangement, with two narrow posterior acetabula located adjacent to each other behind the genital pore; length genital pore 57, width 16, width genital field 156. Pedipalp of typical proportions with a long denticulate ventral projection on P2, ventral denticles (~papillae sensu Cook, 1986) on the anterior three-quarters of P3 and ventral setae on P4 located on the anterior one-third of the segment; length PI –PV 33, 106, 74, 128, 46. Swimming setae absent. Length I-Leg-3–6 73, 114, 122, 129; II-Leg-3–6 83, 129, 143, 150; III-Leg-3–6 97, 167, 187, 170; IV-Leg-3–6 132, 202, 212, 177.

Female: body length 588, width 486. Dorsum papillose, without plates. Infracapitulum length 219. Epimera as in male. Genital plates, each with three acetabula in a triangular arrangement, with two narrow posterior acetabula, length genital pore 128; length genital plate 114, width 59. Pedipalp length PI –PV 34, 104, 75, 129, 42. Swimming setae absent. Length I-Leg-3–6 76, 139, 132, 142; II-Leg-3–6 97, 160, 160, 167; III-Leg-3–6 111, 191, 212, 184; IV-Leg-3–6 150, 223, 240, 202.

Etymology. This species is named after Dr Charles Henn, Bangkok, for his help in collecting water mites in Thailand.

Remarks. The combination of elongate genital acetabula and papillose cuticle is diagnostic of the species. There are a number of similar Asian and Australian Hygrobates species that are separated primarily on small differences in palp structure: H. grimshawi Cook, 1969 [ India], H. orientalis Lundblad, 1969 [ Burma and Malay Peninsula*], H. limi Wiles, 1991 [Malay Peninsula], H. henni sp. n. [ Thailand], H. australicus Cook, 1986 ” [ Australia] and H. projectus Wiles, 1990 [Sulawesi, Buton*]. Hygrobates henni seems to be a larger version of H. limi but with papillate integument and more elongated acetabula. Hygrobates grimshawi and H. orientalis have ventral denticles restricted to the distal end of P3 and a long P2 ventral projection. Hygrobates grimshawi has the longest denticles. Hygrobates australicus has more extensive denticle distribution and a shorter P2 projection than H. grimshawi and H. henni . The P4 ventral setae of H. henni and H. limi are located distally, the ventral margins of P2 and P3 are straight or convex and E2 are located at the medial end of the thickened part of the suture EpIII/EpIV. By contrast, H. orientalis and H. australicus have medially located P2 ventral setae, concave ventral margins to P2 and P3 and E2 are just posterior to a longer EpIII/IV suture.

Figures

FIG. 3. Hygrobates henni new species. (a) Venter ”; (b) venter „; (c) pedipalp „. Scale bar: 90 Mm (a, b); 23 Mm (c).