circuloides Monatractides, Halik, 1930,

Pesic, Vladimir, Semenchenko, Ksenia A., Chatterjee, Tapas, Yam, Rita S. W. & Chan, Benny K. K., 2011, New records of water mites of the family Torrenticolidae (Acari, Hydrachnidia) with descriptions of two new species from Nanshih River system in Taiwan and redescription of Torrenticola ussuri, ZooKeys 116, pp. 1-14: 7-9

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circuloides Monatractides


Monatractides circuloides ( Halik, 1930)  cf. Fig. 7 B–D

Material examined.

Taiwan, Tonghou River, 24°50'23.74"N, 121°38'10.06"E, 25.viii.2009, 2/0/0 (1/0/0 mounted); ibid., 24°50'23.74"N, 121°38'26.52"E, 15.vii.2009 3/0/0; ibid., 25.viii.2009 1/1/0; ibid., Nanshih River, 24°54'09.87"N, 121°33'20.74"E, 02.iii.2010, 0/1/0 (0/1/0 mounted); ibid., 25.viii.2009, 0/1/0; Xindian River, 24°56'52.27"N, 121°32'42.54"E, 2/0/0; ibid., 24°56'19.41"N, 121°31'38.38"E, 26.viii.2009 2/0/0.


Male. Idiosoma L 966, W 719; dorsal shield L 806, W 600, L/W ratio 1.34; dorsal plate L 754; shoulder plate L 219, W 84, L/W ratio 2.6; frontal plate L 147, W 75, L/W ratio 1.85; shoulder/frontal plate L ratio 1.5; capitular bay L 188, its lateral margin with the three pairs of knob-shaped protrusions; Cx-1 total L 326, Cx-1 medial L 138, Cx-2+3 medial 127; ratio Cx-1 L/Cx-2+3 medial L 2.57; Cx-1 medial L/Cx-2+3 medial L 1.09; genital field L/W 188/144, L/W ratio 1.3; ejaculatory complex L 259; distance genital field–excretory pore 227, genital field–caudal idiosoma margin 320. Capitulum ventral L 220; chelicera L 262; palp total L 254, dL: P-1 29, P-2 83, P-3 47, P-4 63, P-5 32; P-2/P-4 ratio 1.3; P-4 with well visible denticle near the insertion of the ventral hairs; L I-L-4-6: 127, 120, 123.

Female. Idiosoma L 1094, W 806; dorsal shield L 894, W 687, L/W ratio1.3; dorsal plate L 851; shoulder plate L 213, W 84, L/W ratio 2.54; frontal plate L 150, W 72, L/W ratio 2.08; shoulder/frontal plate L ratio 1.42; capitular bay L 205; Cx-1 total L 328, Cx-1 medial L 123, Cx-2+3 medial 105; ratio Cx-1 L/Cx-2+3 medial L 3.12; Cx-1 medial L/Cx-2+3 medial L 1.17; genital field L/W 206/194, L/W ratio 1.06; distance genital field–excretory pore 264, genital field–caudal idiosoma margin 438; capitulum ventral L 238; chelicera L 258; palp total L 260, L: P-1 29, P-2 85, P-3 50, P-4 64, P-5 32; P-2/P-4 ratio 1.33; L I-L-4-6: 135, 126, 120.


Due to the presence of three pairs of knob-shaped protrusions at the margin of the capitular bay (Fig. 7D), a rounded capitular bay (Fig. 7D), a short capitular rostrum, relatively longer median suture line of Cx-2+3 (Fig. 7 C–D), and the posterior medial region behind the genital field pointed, the specimens from Taiwan agree well with Monatractides circuloides  ( Halík, 1930), a species known from Malaysia and Thailand ( Pešić and Smit 2009, 2010) Differences (in parentheses measurements of male specimen from Malaysia, data taken from Pešić and Smit 2010) are found in its larger idiosoma and palp dimensions (e.g., idiosoma L 881, dorsal shield L 763, genital field L/W 170/134, P-2 L 69, P-4 L 54). Knowledge on the degree of variability of the additional specimens from a wide area is necessary before we can assess the taxonomic status of these populations.


Malaysia, Thailand, Taiwan.