Arrenurus (Brevicaudaturus) rectituberculatus, Smit & Pesic, 2010

Smit, H. & Pesic, V., 2010, New Species Of Water Mites From Oman, With Some Zoogeographical Notes (Acari: Hydrachnidia), Acarologia 50 (2), pp. 151-195 : 191-192

Arrenurus (Brevicaudaturus) rectituberculatus n. sp.

( Figures 31 A-E, 32A-C)

Type material — Holotype male, Wadi Hanna , Oman, 17°03.236 N 54°36.489 E, 4-xi-2008 . Paratypes: 1/2/0, same data as holotype.

Diagnosis — Male with a large rectangular hump near posterior margin, between pygal lobes; dorsal furrow very short. Female with laterally widened genital plates.

Description

Male — Idiosoma yellowish, L 1183 (1183), W (including humps) 1110 (1134). Anterior idiosoma margin straight to slightly convex. Eyes on small humps, D1 on very large humps. Cauda short, pygal lobes distinct. Between pygal lobes, dorsally a rectangular hump, which extends beyond posterior idiosoma margin. Dorsal shield incomplete, dorsal furrow very short, lying between D1 ( Fig. 31A ). Cx- I extending beyond anterior idiosioma margin. Suture lines between coxal plates indistinct. Gonopore L 90. Genital dield wing-shaped, indistinct, posterior margin with a row of long setae ( Fig. 31B ). Palp ( Fig. 31 D-E): total L 364; L: P-1, 40; P-2, 102; P-3, 66; P-4, 106; P-5, 50; P-2 anteroventrally with three setae, more medially another seta; P-3 anterodorsally with one seta. L of I-Leg-4-6: 178, 194, 267. L of IV- Leg-4-6: 259, 227, 203; IV-Leg-4 without spur. Third and fourth legs with numerous swimming setae.

Female — Idiosoma L 1539, W 1458. Anterior margin slightly concave. D1, D4 and L4 on large humps, L3, V2 and V3 on smaller humps. Posterior idiosoma margin indented. Dorsal shield ( Fig. 32A ) complete, L 786, W 867. Cx-I extending just beyond anterior idiosoma margin ( Fig. 32B ). Suture lines of coxal plates indistinct. Medial corner of Cx-IV rounded. Genital plates indistinct (and therefore not illustrated in lateral view), long and bowed, widened laterally. Gonopore L 156. Palp: total L 403; L: P-1, 48; P-2, 114; P-3, 60; P-4, 129; P-5, 52; palp as in male. L of I-Leg-4-6: 211, 211, 259. L of IV-Leg-4-6: 284, 255, 211. Third and fourth legs with numerous swimming setae.

Etymology — Named after the rectangular posterodorsal hump of the male.

Remarks — The very short dorsal furrow of the male, resulting in the almost absence of a dorsal shield, is quite unusual. Complete absence of a dorsal shield is also found within the genus Thorophoracarus Viets. Cook (1974) postulated the hypotheses that Thorophoracarus has arisen several times from divergent Arrenurus stock. The male of the new species, with hardly a dorsal furrow, could support this hypotheses. The female shares some characters with other Brevicaudaturus species, like the long bowed genital plates and the shape of the posterior idiosoma margin. It is most close to A. moorei Green, 1974 from Cameroon, an insufficiently described species, only known from the female sex. The female of the new species differs from A. moorei in the laterally widened and shorter genital plates (not widened and longer in A. moorei ).

Figures

FIGURE 31: Arrenurus rectituberculatus n. sp., male: (A) – idiosoma, dorsal view; (B) – idiosoma, ventral view; (C) – idiosoma, lateral view; (D-E) – palp. Scale bars = 200 µm (A-C), 50 µm (D-E).

FIGURE 32: Arrenurus rectituberculatus n. sp., female: (A) – idiosoma, dorsal view; (B) – idiosoma, ventral view; (C) – idiosoma, lateral view. Scale bars = 200 µm.