Arrenurus (Micruracarus) botswanicus, Smit, 2012

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 : 20

Arrenurus (Micruracarus) botswanicus n. sp.

( Figs. 50–54)

Material examined. Holotype male, tributary of Okavango River near Drotsky’s Camp, south of Shakawe, Botswana, 23-vii-1996 ( RMNH) . Paratypes: three males, seven females, same data as holotype ( RMNH) .

Other material. BOTSWANA. 38/20/0, ditch along Okavango swamp at Drotsky’s Camp , south of Shakawe, Botswana, 18° 25’ 24,2” S 21° 53’ 28,17” E, 23-vii-1996 ; 1/6/3, Chobe River , Kasane, 17° 47’ 43,34 S 25° 13’ 23,00 E, 17-vii-1996 .

Diagnosis. Cauda little set off from anterior idiosoma part, somewhat rectangular in shape; petiole rectangular, upper part with a rounded indentation.

Description. Male: Idiosoma brownish-green, 753 (676–745) long and 640 (575–640) wide; anterior margin slightly concave. Dorsal shield complete, circular, 409 (381–405) long and 389 (368–373) wide. Cauda little set off from anterior idiosoma. Cauda with a concavity, posterior margin of cauda hyaline. Anterior margin of caudal concavity with a hyaline margin, this hyaline margin ending medially with a rectangular corner. Posterior margin of cauda with a cleft, which is widened anteriorly. Petiole tube-like, lower part rectangular in shape with sclerotized medial margins, upper part with a rounded indentation. Anterior coxal plates not extending to anterior idiosoma margin. Medial margin of third coxal plates longer than medial margin of fourth coxal plates. Medial corner of fourth coxal plates absent. Gonopore 52 long. Genital plates long and narrow, extending far onto dorsum. Lengths of PI-PV: 32, 72, 46, 92, 48; PII with three long setae near anterior margin. Lengths of I-leg-4-6: 130, 120, 128. Lengths of IV-leg-4-6: 150, 136, 106; IV-leg-4 without a spur.

Female: Idiosoma brownish-green, 713 (713–770) long and 632 (620–705) wide, anterior margin convex, posteriorly truncated. Dorsal shield complete, 518 (518–551) long and 397 (389–437) wide. Anterior coxal plates extending beyond anterior idiosoma margin. Medial margin of third coxal plates slightly longer than medial margin of fourth coxal plates or of equal length. Distance of fourth coxal plates almost as long as width of one genital valve. Posterior margin of fourth coxal plates concave. Gonopore 134 long and 170 wide, genital valves with large rounded sclerotized patches. Genital field approximately 494 wide, genital plates sloping and extending to lateral idiosoma margin (but in other paratypes not reaching lateral idiosoma margin), laterally slightly enlarged. Lengths of PI-PV: 30, 69, 38, 86, 44; palp as in male. Lengths of I-leg-4-6: 110, 104, 102. Lengths of IV-leg-4-6: 126, 128, 100.

Etymology. Named after the country of the type locality.

Remarks. The new species belongs to a large group of Afrotropical species with a hyaline tube-like petiole. Identification is not always easy, as the petiole of these species is sometimes a complicated structure and difficult to illustrate. Moreover, some illustrations in the older literature are sketchy. Most similar to the new species are A. damkoehleri , A. larochei and A. bechuanicus n. sp. The petiole of A. larochei is much narrower, while the medial margin of the third coxal plates is shorter than the medial margin of the fourth coxal plates. Arrenurus damkoehleri is larger (832–915, K.O. Viets 1972), and the petiole is of different shape (compare Fig. 13 of K.O. Viets 1972 with Fig. 52). The widened petiole of A. bechuanicus n. sp. will easily distinguish this species from A. botswanicus , as well as from other species of this group. Arrenurus kissi Bader, 1968 also has a hyaline posterior margin (although larger), but has a different petiole. Females of this group are difficult to separate, but the shape of the third and fourth coxal plates in combination with the shape of the genital field might be characteristic for A. botswanicus . It co-occurs with A. bechuanicus n. sp., but the latter species is larger.