Hydrachna cordata, 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 : 172-174

Hydrachna cordata n. sp.

( Figs. 2A–E )

Material examined. Holotype male, Lake Emma, Lakefield NP, Queensland, Australia, 15º 17’47.43” S 144º 38’48.05” E, 3-ix-2000 (QM). Paratypes: 1 female (mounted, QM), 2 females ( RMNH), same data as holotype. Diagnosis. Genital field of male heart-shaped; dorsum with a large frontal shield.

Description. Male: L/W 1849/1749. Frontal shield one large plate, not incorporating the eyes, somewhat irregularly shaped, 802 long and 1005 wide. Posteromedial extension of fourth coxal plates rather narrow, with only a slight development of secondary sclerotization; anterior and third coxae without secondary sclerotization. First, third and fourth coxae with one seta. Genital field heart-shaped, with a large anterior indentation, 300 long and 284 wide; two acetabula distinctly larger than other acetabula. Length of PI-PV: 160, 143, 208, 86, 38; L/H PIII 3.15. Chelicera 794 long. Length of IV-leg-4–6: 389, 397, 251.

Female: L/W 2080 (2131–2432)/1916 (1608–1769). Frontal shield one large plate, not incorporating the eyes, 884 long and 1206 wide. Posteromedial extension of fourth coxal plates wide, with only a slight development of secondary sclerotization; anterior coxae with a slight development of secondary sclerotization, third coxae without secondary sclerotization. First, third and fourth coxae with one seta. Genital field indented anteriorly, with two large acetabula and many small ones, 292 long and 300 wide. Length of PI–PV: 227, 162, 219, 72, 50; L/H of PIII 3.3. Length of IV-leg-4–6: 437, 405, 267.

Etymology. Named for the heart-shaped genital field of the male.

Remarks. The combination of a large frontal plate and heart-shaped genital field of the male is diagnostic for the species. The female is close to H. novaehollandica n. sp. in the presence of a large frontal shield, but differs in wider posteromedial extensions of the fourth coxae.

Figures

FIGURE 2. A – E. Hydrachna cordata n. sp., A – D holotype male, E paratype female. A = frontal shield; B, E = coxal and genital area; C = genital field; D = palp;. Scale bars: A – B, E = 200 µm, C – D = 50 µm.