Arrenurus (Arrenurus) nausoriensis, Smit, Harry, 2004

Smit, Harry, 2004, Water mites from Pacific Islands (Acari: Hydrachnidia), Zootaxa 588, pp. 1-20 : 15-16

Arrenurus (Arrenurus) nausoriensis n. sp.

(Figs. 25–31)

Material examined

Holotype male, small lake Nausori Highlands, Viti Levu, Fiji, 523 m a.s.l., 17º 48.596 S –177º 40.965 E, 23 October 2003. Paratype: 1 female, same data as holotype. Other material: 1 nymph, same data as holotype.

Diagnosis

The shape of the petiole, with its posterior margin with two teeth, extending well beyond the posterior margin of the petiole, is diagnostic for the male. The female is characterised by the large humps on which L4 are located, and the shape of the genital plate, with its anterior margin directed almost perpendicularly to the lateral body margin.

Description

Male: Body 1272 long and 1025 wide; body colour brownish. Anterior body margin concave. Dorsal shield (Fig. 25) reversed pear­shaped, dorsal furrow near complete; dorsal shield 818 long and 535 wide. D1 on large humps, but humps not yet completely sclerotised. Without distinct cauda, pygal lobes large, but these lobes not completely sclerotised. Gonopore 52 long. Genital plates long, slightly contracted laterally (Fig. 28). V2 on small humps. Excretory pore on a large sclerite. Petiole on a basal piece, on which the associated setae are located. Petiole without ligulate process, posterior margin with two teeth (Fig. 26). Hyaline membrane large, with a convex posterior margin. Lengths of PI–PV: 50, 94, 90, 102, 62; PII with three setae on medial side, two of these in anteroventral corner of segment (Fig. 29). Lengths of I­leg­4­6: 202, 178, 228. I­leg­6 and II­leg­6 setose. Lengths of IV­leg­4­6: 332, 194, 235; IV­leg­4 with a spur. Second, third and fourth legs with numerous swimming setae.

Female: body 1432 long and 1306 wide; body colour brownish. Dorsal shield ( Fig. 30 ) complete, slightly tapering posteriorly, 923 long and 583 wide. D1 and L4 on large humps. Anterior body margin concave. First coxal plates not extending beyond anterior body margin. Medial margin of fourth coxal plates longer than medial margin of third coxal plates ( Fig. 31 ). Gonopore with a small chitinous patches, 130 long and 186 wide. Genital plates short and broad, genital field 713 wide. V2 on small humps. Lengths of PI–PV: 36, 88, 90, 102, 60; medial side of PII with five setae. Lengths of I­leg­4­6: 194, 178, 190. Lengths of IV­leg­4­6: 258, 246, 236. Second, third and fourth legs with numerous swimming setae.

Etymology

Named after the Nausori Highlands.

Remarks

The new species belongs to a group of Australian species which all have a similar body shape. To this group belong Arrenurus balladoniensis Halík , A. fissipetiolatus Lundblad , A. acutipetiolatus Smit and A. kimberleyensis Smit. It is most similar to the latter, but the male of this species differs in having a petiole which widens distally, and the doubleteethed extension extends further beyond the posterior margin of the petiole ( Fig. 32 ). The petiole of A. nausoriensis widens gradually, while the double­teethed extensions hardly extends beyond the posterior margin of the petiole. Moreover, the dorsal furrow of A. kimberleyensis is distinctly incomplete, while it is near complete in the new species. Finally, the excretory pore of A. nausoriensis is situated on much more elongated sclerite. The female of A. kimberleyensis has L4 on much smaller humps compared to the new species, the anterior margin of the genital plate is directed more perpendicularly to the lateral body margin (oblique in A. nausoriensis ) and the posterior margin of the genital plate is distinctly indented in A. kimberleyensis , while it is almost without any indentation in A. nausoriensis .

Figures

FIGURE 32. Arrenurus kimberleyensis Smit, paratype male, detail of petiole, ventral view. Scale line = 50 µm.

FIGURES 30 – 31. Arrenurus nausoriensis n. sp., paratype female. 30 = dorsal view; 31 = ventral view. Scale lines: 200 µm.