Arrenurus (Megaluracarus) grampiansensis, Smit, Harry, 2010

Smit, Harry, 2010, Australian Arrenurus (Acari, Hydrachnidia) with the description of eleven new species, Zootaxa 2541, pp. 1-26 : 7-10

Arrenurus (Megaluracarus) grampiansensis n. sp.

( Figs. 5A–E )

Material examined. Holotype male, Pool Green’s Creek, Grampians NP, Victoria, Australia, 37° 18.321 S 142° 23.648 E, alt. 226 m, 15 March 2008 ( NMV). Paratypes: one male ( ZMAN), one female ( NMV), same data as holotype.

Diagnosis. Idiosoma length of male between 1200–1300; male with a posteriorly widened cauda, posteriorly with a short, obliquely located seta; genital field of male short and rounded; palp with two different types of setae, dorsally stout and grooved and ventrally thin setae. Female with strong sloping posterior margins of the fourth coxal plates.

Description. Male: Idiosoma 1247 (1223) long and 593 (599) wide; idiosoma greenish, cauda posteriorly purple-orange. Idiosoma anterodorsally with a half-circular part without body pores. Anterior margin of idiosoma convex. Dorsal shield incomplete, 454 (446) wide. Posterior margin of cauda with a shallow indentation; cauda posteriorly with an oblique, stout seta ( Fig. 5A ). Cauda in lateral view strongly convex, posterior margin straight ( Fig. 5C ). Anterior coxae not extending to anterior idiosoma margin. Gonopore 56 long. Genital plates short and rounded ( Fig. 5B ), width of genital field 251. Lengths of PI-PV: 38, 84, 48, 90, 44. PII with a large patch of setae, these setae in the dorsal half of the patch stout and grooved (and setae hardly visible individually), in the ventral half thinner and not grooved ( Fig. 5D ). PIII with a long medially located seta. Lengths of I-leg-4-6: 170, 190, 160; I-leg-6 with numerous thin, long setae. Lengths of IV-leg-4- 6: 235, 176, 227; IV-leg-4 with a short, triangular spur.

Female: Idiosoma 1215 long and 940 wide; anterior margin convex, posterolateral corners of idiosoma indistinct. Dorsal shield complete, 944 long and 786 wide. Anterior coxal plates not extending to anterior idiosoma margin. Medial margin of third and fourth coxal plates of equal length. Medial distance of third+fourth coxal plates about the same as width of one genital valve. Posterior margin of fourth coxal plates sloping towards lateral idiosoma margin. Gonopore 170 long and 164 wide, medially with an undulating strip of chitinization ( Fig. 5E ). Genital plates short and rounded (and slightly different from each other in shape). Lengths of PI-PV: 41, 100, 64, 102, 48; palp as in male. Lengths of I-leg-4-6: 160, 168, 130. Lengths of IVleg-4-6: 219, 243, 215.

Etymology. Named after the Grampians National Park.

Remarks. The new species is very close to A. niveensis n. sp., the latter being larger (well over 1400) with the posterior part of the cauda more rectangular. In lateral view the dorsal margin of the cauda of A. grampiansensis n. sp. is much more convex compared to A. niveensis n. sp.. The two species agree in the shape of the palp (albeit of different size), with two types of setae in the patch of PII. The female is smaller than A. niveensis n. sp., and has the posterior margin of the fourth coxal plates sloping more strongly. Moreover, the undulating strip of sclerotization of the female gonopore differs from A. niveensis n. sp..

Figures

FIGURE 5 A – E. Arrenurus grampiansensis n. sp., (A – D holotype male, E paratype female): A = dorsal view; B = ventral view; C = lateral view cauda; D = palp; E = ventral view. Scale bars A – C, E = 200 µm; D = 50 µm.