Hydrachna longiscutata, Smit, Harry, 2014

Smit, Harry, 2014, Australian water mites of the genus Hydrachna Müller, with the description of five new species (Acari: Hydrachnidia: Hydrachnidae), Zootaxa 3827 (2), pp. 170-186 : 176-178

Hydrachna longiscutata n. sp.

( Figs. 7A–F )

Material examined. Holotype male, Artificial pool, Rockhole Loop, Mutawintji NP, New South Wales, Australia, 31-x-2001 (AMS). Paratype: female, Temporary pond along Wyseby road (= road to Carnarvon NP), Queensland, Australia, 24º 59.185 S 148º 24.416 E, alt. 305 m asl, 30-x-2005 (QM).

Diagnosis. Dorsum with two narrow, rod-shaped frontal plates. Male genital field heart-shaped.

Description. Male: Idiosoma 2190 long and 1829 wide. Dorsum with two narrow, rod-shaped frontal plates, 713 long. Fourth coxae almost without posteromedial extensions, secondary sclerotization posteromedially of fourth coxae small. First and third coxae each with one small seta, fourth coxae with two small setae. Genital field with numerous acetabula, 445 long and 462 wide, heart-shaped, with a shallow anterior indentation, area between the parts with acetabula sclerotized; gonopore approximately 122 long. Length of PI-PV: 170, 124, 170, 72, 40; PIII stocky, L/H 2.0. Length of I-leg-4–6: 162, 174, 162. Length of IV-leg-4–6: 470, 413, 267.

Female: Idiosoma length approximately 2010 (idiosoma no longer in original shape), width not measurable. Frontal sclerites as in male, 591 long. Fourth coxae almost without posteromedial extensions. First and third coxae each with one small seta, fourth coxae with two setae. Genital field 251 long and 459 wide, anteriorly deeply indented; genital field with numerous small acetabula and a pair of larger acetabula near posterior margin, area without acetabula sclerotized, area with acetabula with 1–3 small setae, near posterior margin two groups of 10–12 setae. Length of PI–PV: 176, 120, 180, 74, 42; L/H PIII 2.1. Chelicera 761 long. First and fourth leg not measurable.

Etymology. Named for the elongate rod-shaped frontal sclerites.

Remarks. Only two other Hydrachna species have similar rod-shaped sclerites, i.e. H. brevirostris Lundblad, 1969 from Burma and the Palaearctic H. crassipalpis Piersig, 1897 . The male of the latter species does not have a heart-shaped genital field, H. brevirostris has very broad rod-shaped sclerites, while the fourth coxae have a distinct posteromedial extension. All three species with rod-shaped sclerites have stocky palps.

Figures

FIGURE 7. A – F. Hydrachna longiscutata n. sp., A – D holotype male, E – F paratype female. A = frontal shield; B = ventral view; C = genital field; D = palp and capitulum; E = coxal and genital area; F = genital field. Scale bars: A – B, D – E = 200 µm; C, F = 50 µm.