Atractides (Atractides) cognatus ( K. Viets, 1935 )

Pesic, Vladimir & Smit, Harry, 2009, New records of water mites of the genus Atractides Koch, 1837 (Acari: Hydrachnidia, Hygrobatidae) from Thailand, Malaysia and Sulawesi (Indonesia), with the description of four new species, Zootaxa 2240, pp. 1-30 : 21-25

Atractides (Atractides) cognatus ( K. Viets, 1935) nov. stat.

( Figs. 15A–D , 16A–C , 17A–D )

Atractides spatiosus cognatus ( K. Viets, 1935)

[syn. to A. spatiosus ( K. Viets, 1935) ; Lundblad 1971 – rejected synonymy]

Material. THAILAND: unnamed creek crossing track from watchtower, Khao Yai NP 11.xi.2007, 14° 27.533 N 101° 20.386 E, leg. Smit, 2/6/0 (1/1/0 mounted); fast flowing stream crossing road to Den Ya Kat Station, alt. 410 m, Chiang Dao NP, 23.xi.2007, 19 ° 19.735 N 98° 56.201 E, leg. Smit, 0/1/0; stream near Ban Khoom, alt. 756 m, Doi Ang Kang, 20.xi.2007, 19° 56.905 N 99° 0 3.938 E, leg. Smit, 3/8/0 (1/1/0 mounted). MALAYSIA: small tributary of Tahan River, Taman Negara NP, 07.ii.2008, 4° 23.977 N 102° 24.162 E, alt. 94 m, leg. Smit, 0/1/0; tributary of Tahan River near Lata Berkoh, Taman Negara NP, 9.ii.2009, 4° 26.635 N 102° 23.057 E, alt. 82 m, leg. Smit, 0/1/0 (0/1/0 mounted). INDONESIA, Sulawesi Utara: stream 18 km west of Molibagu, 16.iv.1991, leg. Smit, 0/2/0 (0/1/0 mounted).

Morphology. General features. Integument dorsally striated. Muscle attachment plates unsclerotized. Genital field: Ac in obtuse triangle; excretory pore smooth; Vgl-1 not fused (but occasionally close or fused in males with Vgl-2). Palp with a weak sexual dimorphism; ventral margin of P-2 straight, sword seta of P-4 near distal hair. I-Leg: setae S-1 and -2 distanced, S-1 near the ventral seta, long, pointed, S-2 pointed, strongly enlarged; I-L-6 very long and slender, thickened basally, with parallel dorsal and ventral margins from the centre to the claw pit.

Male (from stream near Ban Khoom, Thailand; in parentheses specimen from unnamed creek crossing track from watchtower, Thailand): Idiosoma L/W 403/284; Coxal field ( Fig. 15A ): L 252 (222), Cx-3 W 269 (240), Cx-1+2 mL 97 (86), Cx-1+2 lL 163 (144). Palp ( Fig. 15C ): total L 211 (199), dL: P-1 24 (24), P-2 46 (42), P-3 50 (48), P-4 67 (61), P-5 24 (24); %L: P-1 11.4 (12.1), P-2 21.8 (21.1), P-3 23.7 (24.1), P-4 31.8 (30.7), P-5 11.4 (12.1); L P-2/P-4 0.69 (0.69). Genital field ( Fig. 15B ): L/W 76/92, L Ac-1-3: 27-29: 32-34: 29-30.

I-Leg ( Fig. 15D ): I-Leg-5 dL 129 (121), vL 74 (74), dL/vL 1.74 (1.64), HB 32 (31), dL/HB 4.0 (4.0), S-1 L 73 (75), L/ W 10.7 (9.9), S-2 L 56 (57), L/ W 5.7 (5.4), distance of sword setae at I-Leg-5 20 (19), L S-1/2 1.3 (1.32); I-Leg-6 L 106 (104), HB 12 (12), L/HB 8.8 (8.7); L I-Leg-5/6 1.22 (1.16).

Female (from stream near Ban Khoom, Thailand; in parentheses specimen from unnamed creek crossing track from watchtower, Thailand; in square brackets specimen from tributary of Tahan River near Lata Berkoh, Malaysia): Idiosoma L/W 694 (894) [509]/519 (709) [372]; Coxal field: L 331 (370) [284], Cx-3 W 400 (441) [356], Cx-1+2 mL 111 (131) [89], Cx-1+2 lL 206 (234) [186]. Palp ( Fig. 16C ): total L 290 (318) [267], dL: P-1 27 (33) [29], P-2 61 (64) [55], P-3 79 (88) [71], P-4 91 (99) [79], P-5 32 (38) [33]; %L: P-1 9.3 (10.4) [10.9], P-2 21.0 (20.1) [20.6], P-3 27.2 (27.7) [26.6], P-4 31.4 (31.1) [30.0], P-5 11.0 (12.0) [12.4]; L P- 2/P-4 0.67 (0.65) [0.7]. Genital field ( Fig. 16B ): L (150)/W (154), genital plate L 114 (108) [85], L Ac-1-3: 37 (32-35) [30]-42 (30-35) [33]-42 (35-36) [34].

I-Leg ( Fig. 16A ): I-Leg-5 dL 194 (210) [171], vL 98 (121) [100], dL/vL 1.98 (1.74) [1.7], HB 44 (48) [43], dL/HB 4.4 (4.4) [4.0], S-1 L 103 (125) [109], L/ W 8.5 (10.5) [10.3], S-2 L 69 (83) [65], L/ W 4.1 (4.5) [4.3], distance of sword setae at I-Leg-5 49 (39) [33], L S-1/2 1.5 (1.5) [1.7]; I-Leg-6 L 146 (179) [138], HB 13.6 (14) [12], L/HB 10.7 (13.0) [11.2]; L I-Leg-5/6 1.33 (1.17) [1.24].

In addition we give measurements of the female from Sulawesi which are suspected to belong to the same species (general differences see below in the “remarks”-section).

Female: Idiosoma L/W 806/619. Coxal field ( Fig. 17A ): posterior margin Cx-1 strongly indented; Cx-1+2 mL 97, Cx-1+2 lL. Palp ( Fig. 17B ): total L 296, dL and %L (in parentheses): P-1 31 (10.5), P-2 64 (21.6), P-3 78 (26.4), P-4 86 (29.1), P-5 37 (12.5); L P-2/P-4 0.74. Genital field ( Fig. 17C ): L/W 136/144, genital plates bean-shaped, L genital plate 100-102, Ac-1-3: 32-33-33.

I-Leg ( Fig. 17D ): I-Leg-5 dL 188, vL 110, dL/vL 1.7, HB 53, dL/HB 3.6, S-1 L 112, L/ W 10.6, S-2 L 74, L/ W 4.4, distance of sword setae at I-Leg-5 42, L S-1/2 1.5; I-Leg-6 L 155, HB 11, L/HB 14.1; L I-Leg-5/6.

Remarks. In the original description K.Viets (1935) compared A. cognatus with A. spatiosus , believing it to be a subspecies of the latter. He noticed the following differences: in A. spatiosus the sword seta of P-4 was inserted halfway between ventral hairs, Cx-3+4 medially indented; in A. cognatus the sword seta of P-4 was close to the distoventral hair, Cx-3+4 medially straight. Later on, Lundblad (1971) showed that differences in shape of posterior coxae and length and direction of medial apodemes of Cx-1, were insignificant and that A. cognatus should be considered a junior synonym of A. spatiosus . This conclusion, however, contradicted by other morphological evidence. Atractides spatiosus (in parentheses data taken from K. Viets 1935) differs from A. cognatus in longer I-Leg-5-6, a more distant S-1 and - 2 on I-Leg-5 (> 40 in both sexes). However, because some important characters such as the S-1 and -2 interspace in the male were lacking in the original description (K Viets 1935), our assignment of A. cognatus is still provisional. The variability of further male and female specimens of A. cognatus from the area of type locality (South Sumatra, Ranau), needs to be examined to clarify the taxonomy.

The specimens from Sulawesi agree well with the original description ( K. Viets 1935) and with our material from Thailand and Malaysia. However, due to the fact that we do not have male specimens, this is only a tentative assignment.

Distribution. Indonesia (Sumatra, E Java: ‘ Atractides spatiosus cognatus ’ K. Viets 1935 ; Sulawesi: ‘ Atractides spatiosus ’ Smit 1996 ), Malaysia (‘ Atractides spatiosus ’ Wiles 1991 ), Burma (‘ Atractides spatiosus f. cognata ’ Lundblad 1969). New for Thailand.

Figures

FIGURE 15 A – D. Atractides cognatus K. Viets, 1935, male, stream near Ban Khoom, Thailand: A = coxal and genital field; B = genital field; C = palp, medial view; D = I-Leg- 5 and - 6. Scale bars = 100 μm.

FIGURE 16 A – C. Atractides cognatus K. Viets, 1935, female (A, C - specimen from stream near Ban Khoom, Thailand; B- specimen from tributary of Tahan River near Lata Berkoh, Malaysia): A = I-Leg- 5 and - 6; B = genital field; C = palp, lateral view. Scale bar = 100 μm.

FIGURE 17 A – D. Atractides cognatus K. Viets, 1935, female, stream 18 km west of Molibagu, Sulawesi: A = coxal field; B = palp, medial view; C = genital field; D = I-Leg- 5 and - 6. Scale bars = 100 μm.