Africasia rotunda, Smit, 2017

Smit, Harry, 2017, New records of water mites from standing waters in Thailand, with the description of nine new species (Acari: Hydrachnidia), Zootaxa 4312 (1), pp. 69-91 : 82-83

Africasia rotunda n. sp.

( Fig. 8 )

Material examined. Holotype male, Nong Chang Yai Reservoir, Ubon Ratchathani Province, Thailand, 15° 23.874ʹ N, 104° 49.756ʹ E, 25-x-2010 ( RMNH) . Paratypes: 11 males, 12 females ( RMNH), three males and two females ( THAI), same data as holotype; one female, Kud Thing Lake , Nong Khai Province, Thailand, 18° 20ʹ 36 ʺ N, 103° 39ʹ 52 ʺ E, 30-i-2011 ( RMNH) ; one female, Huay Nam Kham Noi rivulet, Yasothon Province, Thailand, 15° 48.779ʹ N, 104° 09.415ʹ E, 10-ii-2011 ( RMNH) .

Diagnosis. Idiosoma yellow, almost circular in shape, dorsal shield without radiating lines, fourth coxae with a distinct medial margin.

Description. In both sexes: Idiosoma yellow, almost circular in shape. Dorsal and ventral shields present, dorsal shield without radiating lines. Cx-I narrow; Cx-IV with a distinct medial margin, much longer than medial margin of third coxae. Lateral ridge of coxal field extending to insertion of fourth legs. Genital plates indistinct, 140 width with numerous small acetabula.

Male: Dorsally 416 (421–437) long; 373 (373–397) wide. Dorsal shield complete, 365 (372–373) long; 312 (308–332) wide. First coxae extending beyond anterior idiosoma margin. Gonopore slit-like, 55 long. Length of P1-5: 22 (24), 40 (40), 28 (30), 46 (50), 18 (20). Palp rotated, P3 with a long dorsomedial seta, P4 with a long anteroventral seta. Length of I-leg-4–6: 52, 70, 78 (to tip). Length of IV-leg-4–6: 62, 80, 94. Swimming setae numbers: III-leg-4 two, -leg-5 three, IV-leg-4 one.

Female: Idiosoma 429 (454–494) long; 429 (413–467) wide. Dorsal shield 397 (405–409) long, 365 (340–373) wide. First coxae extending only slightly beyond anterior idiosoma margin. Gonopore 102 long. Length of P1-4: 24, 42, 26, 56, P5 not measurable. Length of I-leg-4–6: 36, 56, 78 (to tip). Length of IV-leg-4–6: 66, 86, 96 (to tip).

Etymology. Named for its rounded shape.

Remarks. Eleven Africasia -species have been described from the Oriental region. From Malaysia and Sulawesi Africasia cataphracta ( Halík, 1930) is known ( Wiles 2004). The female of this species is smaller, 375 long and 350 wide, has very broad first coxae and the lateral ridge of the coxal field extends far posteriorly beyond the insertion of the fourth legs ( Halík 1930). Africasia insulana Viets, 1935 from Sumatra is much larger (520 long and 465 wide), the first coxae are more pointed and not extending beyond the anterior idiosoma margin ( Viets 1935). Cook (1967) described six species from India. All these species have either radiating lines on the dorsal shield or have a more elongated idiosoma. Africasia acuticoxalis Smit & Pešić, 2014 has medially pointed fourth coxae, is smaller (the female is 365 long and 344 wide) and the dorsal shield has a red patch ( Smit & Pešić 2014). Africasia purpurea Pešić & Smit, 2016 from Laos has the dorsal shield with distinct radiating lines and large purple patches ( Pešić & Smit 2016). Africasia vietnamitica Pešić & Gerecke, 2014 has the gonopore surrounded by the genital field, which broadens posteriorly ( Pešić & Gerecke 2014).

Figures

FIGURE 8. Africasia rotunda n. sp., A – C = holotype male, D = paratype male, E = paratype female. A = dorsum; B = venter; C = gnathosoma and palp; D = palp; E = venter. Scale bars = 50 µm.