Monatractides ventriosus (K. Viets, 1916)

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 : 54-55

Monatractides ventriosus (K. Viets, 1916)

Material examined. Comoros, Mayotte: Koual River, downstream, 12°48'19,5"S 45°09'49,7"E, 08-x-2008, 1/2/0 (1/1/0 mounted); Koual River, legion, 12°47'49,7"S 45°11'08,6"E, 08-x-2008, 17/23/1 (1/1/0 mounted); River Chirini, downstream, 12°46'39,7"S 45°06'16,4" E, 08-x-2008, 82/2; River Comboni, 12°46'17,2"S 45°08'51,1"E, 07-x-2008 2/3/0; River Botirini, 12°45'37,7" S 45°06'42,6" E, 05-x-2008, 52/4 (1/0/0 mounted); Mro oua Goulou (Goulou River), 12°47'27,2"S 45°11'22,9"E, 7-x-2008, 81/2 (1/1/0 mounted); River Ourouveni, downstream (Old Bridge), 12°48'29,9"S 45°07'39,4"E, 2-x-2008, 1/0/0; River Bouyouni, downstream, 12°44'25,3"S 45°08'33,3"E, 5-x-2008, 12/12/0; River Djalimov, downstream, 12°47'14,4"S 45°06'51,7"E, 3-x-2008, 1juvenile /0/0.

Remarks. As already pointed out by Cook (1966), Monatractides ventriosus is an extremely variable species or, more likely, a series of very closely related species which are presently being confused. The specimens from Comoros agree well with the measurements for specimens from South Africa given by K.O.Viets (1965). In addition we give the measurements based on the specimens from Koual River.

Male. Idiosoma L 750, W 669; dorsal shield L 663, W 506, L/W ratio 1.3; dorsal plate 594; frontal plate L 128, W 88, L/W ratio 1.46; shoulder plate L 202, W 84, L/W ratio 2.4; capitular bay L 140, its lateral margin with three pairs of knob-shaped protrusions; Cx-1 total L 272, Cx-1 medial L 131, Cx-2+3 medial 82; ratio Cx-1 L/Cx-2+3 medial L 3.3; Cx-1 medial L/Cx-2+3 medial L 1.6; genital field L/W 141/120, L/W ratio 1.2; ejaculatory complex L 197; distance genital field–excretory pore 148, genital field–caudal idiosoma margin 244; capitulum ventral L 158; chelicera L 225; palp total L 214, dL and %L (in parentheses): P-1, 28 (13.1); P-2, 58 (27.1); P-3, 39 (18.2); P-4, 57 (26.6); P-5, 32 (15.0); L P-2/P-4 ratio, 1.02.

Female. Idiosoma L 813, W 725; dorsal shield L 681, W 556, L/W ratio 1.23; dorsal plate 613; frontal plate L 125, W 91, L/W ratio 1.37; shoulder plate L 209, W 84, L/W ratio 2.5; capitular bay L 144, lateral margin as in males; Cx-1 total L 283, Cx-1 medial L 138, Cx-2+3 medial 55; ratio Cx-1 L/Cx-2+3 medial L 5.2; Cx-1 medial L/Cx-2+3 medial L 2.5; genital field L/W 170/157, L/W ratio 1.08; distance genital field– excretory pore 169, genital field–caudal idiosoma margin 297; capitulum ventral L 163; chelicera L 210; palp total L 218, dL and %L (in parentheses): P-1, 22 (10.1); P-2, 61 (28.0); P-3, 42 (19.3); P-4, 61 (28.0); P-5, 32 (14.7); L P-2/P-4 ratio, 1.0.

Distribution. West Africa ( Cameroon, Liberia), East Africa ( Kenya), Central Africa ( Congo), South Africa, Comoros. The variability of populations from different regions of the whole distribution area needs to be examined to clarify the taxonomy (Smit et al. 2009).