Arrenurus (Arrenurus) capensis Thor, 1902

Smit, H., 2012, New records of the water mite family Arrenuridae from the Afrotropical region, with the description of 11 new species and two new subspecies (Acari: Hydrachnidia), Zootaxa 3187, pp. 1-31 : 2-5

Arrenurus (Arrenurus) capensis Thor, 1902

( Figs. 8–9)

Arrenurus (Arrenurus) vanopus Cook, 1979 — new syn.

Arrenurus (Arrenurus) petri Cook, 1979 —new syn. (part., ♀) Material examined. ETHIOPIA. 0/1/1, Lake Awasa , 7° 02.964 N 38° 27.621 E, alt. 1684 m a.s.l., 3-xi-2006; 6/3/ 0, Lake Awasa , 7° 02.777 N 38° 27.437 E, alt. 1684 m a.s.l., 4-xi-2006 ; 1/1/0, marsh near Lake Awasa, Awasa , 7° 02.964 N 38° 27.621 E, alt. 1684 m a.s.l., 3-xi-2006 ; 1/2/0, Lake Langano , 7° 38.779 N 38° 42.378 E, alt. 1580 m a.s.l., 7-xi-2006 ; 0/1/0, Lake Ziway , 7° 55.514 N 38° 43.544 E, alt. 1747 m a.s.l., 8-xi-2006 . GHANA. 1/5/0, Lake Agbo near Dawenya , 5° 46’ 44,8” N 0° 3’ 4,36” E, 27-xii-2009, leg. P. Wondergem ; 2/2/0, Lake Kokrobite, Weija , 5° 33’ 7,90” N 0° 22’ 34,69´W, 7-i-2010, leg. P. Wondergem ; 1/0/0, Inlet Volta River at Kpong , 6° 09.183N 0° 03.709 W, alt 25 m asl, 7-i-2010, leg. P. Wondergem ; 1/11/0, same location, 10-iii-2011 ; 1/0/0, Drinking water reservoir, W of Accra, 5° 33.133 N 0° 22.147 W, alt. 14 m asl, 21-ii-2011 ; 17/24/1, Lake Bosumtwi , 6° 32.111 N 1° 25.672 W, alt. 102 m asl, 28-ii-2011 .

Compared material. Arrenurus petri Cook – paratype female, Volta Lake , Ghana, feb-nov 1965, leg Petr (slide 1980.12.15.4, BMNH).

Description. Female (from Lake Bosumtwi): Idiosoma colour green, 1286 long and 1045 wide. Anterior idiosoma margin slightly concave. Dorsal shield complete, 851 long and 648 wide. D1 on humps. First coxae not extending to anterior idiosoma margin. Medial margin of fourth coxae larger than medial margin of third coxae. Distance of fourth coxae about the width of one genital valve. Genital field 680 wide. Gonopore 84 long and 154 wide, with a pair of curved strips, which may be in fact the unsclerotized part of the gonopore. Genital plates long, lying almost posteriorly of gonopore. In the illustrated specimen the genital plates are not connected with the gonopore, but in specimens from other locations the genital plates are connected. L4 and V2 on large humps. Lengths of PI-PV: 36, 86, 74, 118, 64. Palp as in male, but medial side PII anteroventrally with four setae (in male one) and more dorsally two more setae (one in male). Lengths of I-leg-4-6: 178, 162, 186. Lengths of IV-leg-4-6: 235, 194, 219.

Remarks. Cook (1979) compared A. vanopus only with A. rouxi Walter, 1915 , but in fact it is closer to the widespread Afrotropical A. capensis Thor, 1902 . The petiole of the two species as well as the hyaline membrane are identical. Based on illustrations in the literature, differences can be found in the shape of the idiosoma and the shape of the hump of V2. Thor (1902) and K.O. Viets (1965) illustrated the species with less deep concave lateral margins, while Cook (1979) illustrated A. vanopus with concave lateral margins, resulting in a cauda more distinctly set off from the anterior idiosoma. A specimen from Egypt ( Schwoerbel 1960) has rather concave lateral margins. In my opinion these differences are of minor importance. In some specimens the glandularia V2 lie on large humps and these can therefore be seen in dorsal view. Thor (1902) and K.O. Viets (1965) illustrate their specimens with small V2-humps, while Cook (1979) illustrated A. vanopus with large humps. In my specimens there is variation in the size of the humps, even in specimens from the same location. Apparently this depends on the age of the specimen. I described and illustrated a female from Ghana, and this female also is similar to females described as A. capensis . Therefore, I consider A. vanopus a junior synonym of A. capensis . Cook (1979) described the female of A. petri Cook , based on a specimen from the same location of A. vanopus Cook. However , this female must be assigned to A. capensis , the female of the latter species was unknown to Cook. The females described by Cook (1979) as A. petri have narrow, bowed genital plates lying almost posteriorly of the gonopore, characteristic for A. capensis .

Arrenurus capensis is widespread in Afrotropical Africa, and has been reported from Egypt to South Africa, and from Ghana to Ethiopia.