Africasia comorosensis Smit & Pesic

Smit, Harry, Pesic, Vladimir & Mary-Sasal, Nathalie, 2010, Second contribution to the knowledge of water mites from the Comoros, with the description of one new species (Acari: Hydrachnidia), Zootaxa 2413, pp. 51-60 : 57-60

Africasia comorosensis Smit & Pesic sp. nov.

( Figs. 4A–B , 5A–B , 6A–C )

Type material. Holotype: female (dorsal and ventral shield separated), fixed in Koenike fluid, Comoros, Mayotte: Koual River, downstream, 12°48'19,5"S 45°09'49,7"E, 08-x-2008 0/1/0. Paratypes: 0/1/0 (0/1/0 mounted), Mro oua Goulou (Goulou River), 12°47'27,2"S 45°11'12,9"E, 7-x-2008; 1/0/0 (1/0/0 mounted), Mro oua Ourouveni, mouth (Ourouveni River, mouth), 02-x-2008.

Diagnosis. Integument of dorsal shield with five areas of radiating lines on inner surface (two pairs of lateral and one posteromedial); dorsal shield with a central raised ridge; central area of dorsal shield with a large, oval reddish patch.

Description. Female (paratype, in parentheses some measurements of holotype). Dorsal and ventral shields present; dorsal shield L 398 (415), W 338 (350); integument of dorsal shield with five areas of radiating lines on inner surface as indicated in Figs. 4A , 5B (two pairs of lateral and one posteromedial); dorsal shield with a central raised ridge and central area of dorsal shield with a large, oval reddish patch as shown in Fig. 5A [in the paratype the colour is hardly visible because of lactate treatment]; ventral shield L 448 (486), W 442 (418); outer margin of ventral shield irregular; anterior coxae projecting; outer margin of Cx-3 and Cx-4 forming a nearly straight line; gonopore L 89 (99), W 82 (79); 24 (25) pairs of acetabula, these on ill-defined acetabular plates; palp ( Fig. 6A ) total L 179, dL and %L (in parentheses): P-1 23, (12.9); P-2, 47 (26.3); P-3, 28 (15.6); P-4, 59 (33.0); P-5, 22 (12.3); L P-2/P-4 ratio 0.8; palpal segments rotated, distal end of the uncate P-4 with one long thin seta and one short somewhat thickened seta; capitulum ventral L 85 (96); L I-Leg-3-6: 40, 45, 66, 78; L IV-Leg: 60, 55, 49, 70, 88, 93; III/IV-Leg-4/5 each with two swimming setae.

Male. Dorsal shield L 347, W 306; integument of dorsal shield with less developed radiating lines on inner surface and a central raised ridge; the colour is hardly visible because of lactate treatment; ventral shield L 406, W 388, similar to female except for region of the genital field; gonopore L 47; 18-22 acetabula on each side; ejaculatory complex L 83; palp total L 160, dL and %L (in parentheses): P-1, 22 (13.8); P-2, 40 (25.0); P-3, 26 (16.3); P-4, 52 (32.5); P-5, 20 (12.5); L P-2/P-4 ratio, 0.77; palp as in the female; capitulum L 75; L I- Leg-3-6: 39, 51, 74, 83; L IV-Leg-4-6: 74, 52, 49, 66, 82, 85; swimming setae as described for the female.

Etymology. Named after the Comoros Islands.

Remarks. Most probably the difference in less developed radiating lines on the inner surface of the dorsal shield is due to the juvenile age of the male (indicated by weak sclerotization with large pores).

Due to the presence of five areas (two pairs of lateral and one posteromedial) of radiating lines on inner surface of dorsal shield, Africasia comorosensis is similar to A. radiata Cook ( Liberia, see: Cook 1966), A. mahadensis Cook ( India, see: Cook 1967) and A. obscuripora (Viets) ( South Africa, see: Cook 2001 for redescription). From these species, A. comorosensis can be distinguished in possessing a central ridge on the dorsal shield. Furthermore, A. obscuripora differs in having lower number of acetabula and a different colour pattern (see: Cook 2001). On the other hand, due to the development of a central ridge on the dorsal shield, A. comorosensis resembles A. rucira Cook , A. navina Cook and A. ruksa Cook , all species known only from a small mountain stream in Kerala, India ( Cook 1967). Of these species, only Africasia rucira is most similar to the new Africasia species from Comoros, but differs in slightly developed radiating thickenings on the inner surface of the dorsal shield, different colour pattern and smaller dimensions of the idiosoma (ventral shield L/ W 416–418/ 35–354 in female, L/W 388/ 304 in male, data taken from Cook 1967).

Distribution. Comoros ( Mayotte).

Habitat. The species was found in downstream sections of small forest streams ( Figs. 5C–D ).

Figures

FIGURE 4 A – B. Africasia comorosensis sp. nov., female: A = dorsal shield; B = ventral shield. Scale bar = 100 μm

FIGURE 5 A – D. A – B. Africasia comorosensis sp. nov., female holotype, dorsal shield: A—outer surface; B—inner surface; C—Koual River (Photo. Mary-Sasal); D—Goulou River (Photo. Mary-Sasal).

FIGURE 6 A – C. Africasia comorosensis sp. nov., (A – B female, C male): A = palp and capitulum; B = I-Leg- 6; C = ventral shield. Scale bar = 100 μm.