Australian Arrenurus (Acari, Hydrachnidia) with the description of eleven new species Author Smit, Harry text Zootaxa 2010 2541 1 26 journal article 10.5281/zenodo.196693 bc71468f-9e9f-49e4-b1f1-9f234f7089cf 1175-5326 196693 Arrenurus (Dividuracarus) neogereckei n. sp. ( Figs. 3A–F ) Material examined. Holotype male, Small lake Hawkwood Road, 13 km S of Mundaburra, Queensland, Australia , 25° 39.910 S 151° 13.941 E , 31 October 2005 (QM). Paratypes : 3 females (QM), 2 females ( ZMAN ), same data as holotype . Diagnosis. Characterized by its complex petiole; central idiosoma part with a rectangular hump. Description. Male: Idiosoma 964 long (without petiole) and 729 wide, divided in three parts, idiosoma colour green. Idiosoma anteriorly truncated, slightly concave. D1 on a small hump, D2 slightly anteromedial of D1. Dorsal idiosoma posteriorly with a rectangular hump ( Fig. 3A ). Anterior coxae not extending to anterior idiosoma margin. Medial margins of third and fourth coxal plates of equal length (or medial length of third coxal plate larger). Gonopore rounded, 50 long. Genital plates indistinct, slightly bowed, laterally widened, extending to lateral idiosoma margin ( Fig. 3B ). Petiole complex, protrusible, laterally with hyaline lamellae, two triangular structures each with two stout setae. In lateral view posteriorly open with a hook-like extension ( Fig. 3C, D ). Lengths of PI-PV: 36, 96, 62, 100, 50; PII medially with three setae, PIV anteroventrally rounded ( Fig. 3E ). Lengths of I-leg-4-6: 136, 144, 150. Lengths of IV-leg-4-6: 259, 184, 166; IV-leg-4 without spur. Second, third and fourth legs with numerous swimming setae. Female: Idiosoma 1069 (940–1158) long and 875 (850–988) wide, anteriorly rounded. Idiosoma strongly truncated anteriorly, and less truncated posteriorly. Dorsal shield complete, 705 (640–745) long and 607 (595– 668) wide. First coxae not extending to anterior idiosoma margin. Medial margin of third coxae larger than medial margin of fourth coxae, medial corner of fourth coxae rounded. Gonopore extending laterally, 162 long and 283 wide. Gonopore medially with chitinized patches, which extends along anterior and posterior margin ( Fig. 3F ). Genital field 535 wide. Genital plates short and broad. Lengths of PI-PV: 36, 88, 50, 104, 47; palp as in male. Lengths of I-leg-4-6: 130, 132, 108. Lengths of IV-leg-4-6: 235, 211, 166. Second, third and fourth legs with numerous swimming setae, first leg with a few swimming setae. FIGURE 3A–F . Arrenurus neogereckei n. sp. , (A–E holotype male, F paratype female): A = dorsal view; B = ventral view; C = lateral view; D = detail of petiole; E = palp, F = ventral view. Scale bars: A–C, E–F = 200 µm; D = 50 µm. Etymology. Named for its resemblance with A. gereckei Smit. Remarks. This is the third species of the subgenus Dividuracarus Smit , a subgenus thus far confined to Australia . The new species is close to A. gereckei Smit, 1997 but the hump on the middle idiosoma part of the male is rectangular (rounded in gereckei ) and the petiole is of different shape (with four stout setae instead of two, laterally with hyaline lamellae which are absent in gereckei ). Moreover, the idiosoma shape is more stocky, while the hump of the dorsal idiosoma part is less pointed. The female is also close to A. gereckei , but the latter species does not have the chitinized patches on the gonopore.