Monatractides circuloides ( Halík, 1930 ), Halik, 1930

Pesic, Vladimir & Smit, Harry, 2009, Water mites of the family Torrenticolidae (Acari: Hydrachnidia) from Thailand, Part II. The genus Monatractides K. Viets, Zootaxa 2012, pp. 1-27 : 2-5

Monatractides circuloides ( Halík, 1930)

( Figs. 7–19 )

Material. Thailand: Stream W of Bankrang Camp, Kaeng Krachan NP, 30.xi.2007, 12° 48.106 N 99° 26.786 E, leg. Smit 0/1/0 (0/1/0 mounted); river at km. 13, 465 m asl, Doi Inthanon NP, 25.xi.2007, 18° 31.532 N 98° 39.091 E, leg. Smit 3/2/0 (1/1/0 mounted).

Morphology. Male (from river at km. 13): Idiosoma (ventral view: Fig. 8 ) L 753, W 600; dorsal shield ( Fig. 7 ) L 622, W 493, L/W ratio 1.26; dorsal plate L 581; shoulder plate L 179, W 68, L/W ratio 2.6; frontal plate L 109, W 59, L/W ratio 1.85; shoulder/frontal plate L ratio 2.6; capitular bay L 134, its lateral margin with the three pairs of knob-shaped protrusions: One pair at the apical tip of Cx-1, two further pairs distally and proximally from the subapical seta; Cx-1 total L 248, Cx-1 medial L 113, Cx-2+3 medial 114; ratio Cx-1 L/Cx-2+3 medial L 2.2; Cx-1 medial L/Cx-2+3 medial L 0.99; genital field L/W 156/122, L/W ratio 1.28; ejaculatory complex L 225; distance genital field–excretory pore 144, genital field–caudal idiosoma margin 216. Capitulum ( Fig. 12 ) ventral L 169; chelicera L 189; palp ( Figs. 10–11 ) total L 197, L and %L (given as % of total L): P-1 23 (11.7), P-2 60 (30.5), P-3 36 (18.3), P-4 52 (26.4), P-5 26 (13.2); P-2/P-4 ratio 1.15; P-4 with well visible denticle near the insertion of the ventral hairs; L I-Leg-4-6 ( Fig. 13 ): 108, 100, 97.

Female (from stream W of Bankrang Camp, in parentheses specimen from river at km 13): Idiosoma (ventral view: Fig. 15 ) L 875 (838), W 688 (688); dorsal shield ( Fig. 14 ) L 731 (689), W 556 (550), L/W ratio 1.3 (1.25); dorsal plate L 688 (650); shoulder plate L 211 (197), W 69 (72), L/W ratio 3.06 (2.7); frontal plate L 131 (109), W 66 (65), L/W ratio 2.0 (1.7); shoulder/frontal plate L ratio 1.6 (1.8); capitular bay L 153 (150), its lateral margin with the three pairs of knob-shaped protrusions: One pair at the apical tip of Cx-1, two further pairs distally and proximally from the subapical seta; Cx-1 total L 288 (266), Cx-1 medial L 135 (116), Cx-2+3 medial 100 (89); ratio Cx-1 L/Cx-2+3 medial L 2.9 (3.0); Cx-1 medial L/Cx-2+3 medial L 1.35 (1.3); genital field L/W 160 (166)/144 (144), L/W ratio 1.1 (1.15); distance genital field–excretory pore 197 (205), genital field–caudal idiosoma margin 313 (316). Capitulum ( Fig. 16 ) ventral L 194 (188); chelicera L 211 (208); palp ( Figs. 17–18 ) total L 221 (218), L: P-1 26 (26), P-2 71 (68), P-3 43 (42), P-4 54 (55), P-5 27 (27); %L (given as % of total L): P-1 11.8 (11.9), P-2 32.1 (31.2), P-3 19.5 (19.3), P-4 24.4 (25.2), P-5 12.2 (12.4); P-2/P-4 ratio 1.3 (1.24); L I-Leg-4-6 ( Fig. 19 ): 121 (120), 106 (112), 109 (111).

Remarks. Due to the presence of three pairs of knob-shaped protrusions at the margin of the capitular bay, a rounded capitular bay, a shorter capitular rostrum, relatively longer median suture line of Cx-2+3, and the posterior medial region behind the genital field pointed, the specimens from Thailand agree well with the description given by Halík (1930) for M. circuloides and by Lundblad (1969) for the same female specimen from Malaysia (Perak), and the description given by Wiles (1991) for the female specimen from Selengor ( Malaysia). Only the female of this species is known, and this is the first description of the male.

Distribution. Malaysia. New for Thailand.

Figures

FIGURES 7 – 13. Monatractides circuloides (Halík), male, river at km. 13: 7 = dorsal shield; 8 = idiosoma, ventral view; 9 = anterodorsal portion of ventral shield; 10 = palp (P- 1 missing), lateral view; 11 = palp, medial view; 12 = capitulum; 13 = I-Leg- 5 - 6. Scale Bars = 100 µm.

FIGURES 14 – 19. Monatractides circuloides (Halík), female, stream W of Bankrang Camp: 14 = dorsal shield; 15 = idiosoma, ventral view; 16 = capitulum; 17 = palp (P- 1 missing), medial view; 18 = palp, lateral view; 19 = I-Leg- 5 - 6. Scale Bars = 100 µm.