Water mites (Acari, Hydrachnidia) from Baishih River drainage in Northern Taiwan, with description of two new species Author Pesic, Vladimir Author Yam, Rita S. W. Author Chan, Benny K. K. Author Chatterjee, Tapas text ZooKeys 2012 203 65 83 http://dx.doi.org/10.3897/zookeys.203.3356 journal article http://dx.doi.org/10.3897/zookeys.203.3356 1313-2970-203-65 Hygrobates (Hygrobates) taiwanicus sp. n. Figs 5-6 Type series. Holotype female (NMNS-6894-001), dissected and slide mounted, Taiwan, BA-3, Chinkualiao Stream, vi.2010. Paratypes: 0/1/0, same data as holotype; 1/1/0 (mounted), BA-1, Chinkualiao Stream, iii. 2010; 0/3/0, BA-4, Diyu Stream, iii.2010; 0/1/0, BA-5, Diyu Stream, iv.2010. Diagnosis. Idiosoma L> 750; acetabula arranged in an obtuse angle; female pregenital sclerite with four setae, its anterior margin extending beyond anterior margin of genital plates; female genital plates longer than gonopore; posterior end of female genital plates posterior to postgenital sclerite; P-2 ventrodostal projection elongate, cone-shaped; proximoventral seta on P-4 longer and thicker than distoventral seta. Description. Female (holotype, in parentheses paratype). Idiosoma L 775 (778), W 613 (706); integument soft, with very fine striation. Capitulum broadly fused with Cx-I. Coxae (Fig. 5A): coxal field L 322 (359), Cx-III W 472 (500), posterior end of anterior coxal group rounded-truncate, Cx-I+II L/W 238 (259)/319 (344), posterolateral apodemes extending slightly beyond sclerotization. Suture line of Cx-III and Cx-IV nearly straight, incomplete, extending to near Cxgl-IV; medial margin of Cx-IV rounded-triangular. Genital field (Fig. 5A-B): L/W 181 (213)/173 (203), acetabular plates with smooth border, L 143-147 (175); acetabula arranged in an obtuse triangle, L Ac-1-3: 55-56 (66), 55-58 (72), 44 (66-68); pregenital sclerite with four setae, its anterior margin extending beyond anterior margin of genital plates. Excretory pore smooth. Palp (Fig. 5E): total L 358 (423), dL: P-1, 26 (34); P-2, 98 (111); P-3, 70 (85); P-4, 121 (136); P-5, 43 (57); dL P-2/P-4 ratio, 0.81 (0.82); chelicera (Fig. FD) total L 250 (319), basal segment L 157 (200), claw L 100 (125), L ratio basal segment/claw 1.6 (1.6). Legs: dL of I-L-2-6 (Fig. 6A): 69 (89), 90 (109), 131 (156), 134 (159), 138 (161); dL of IV-L (Fig. 6B): 108 (128), 103 (128), 151 (184), 213 (263), 225 (272), 193 (234). Males (n = 2): similar to female, except for genital field. Idiosoma L 775-794, W 625-656; coxal field L 338, Cx-III W 463, Cx-I+II L/W 231/334; genital field L/W 160-170/148-151, anterior margin convex, L Ac-1-3: 51-58, 63-66, 63-66; ejaculatory complex L 169. Palp (Fig. 5C): total L 365-373, dL: P-1, 28; P-2, 99-100; P-3, 71-75; P-4, 119-123; P-5, 48-47; dL P-2/P-4 ratio, 0.81-0.83; chelicera: basal segment L 194, claw L 103, L ratio basal segment/claw 1.9. Legs: dL of I-L-2-6: 74, 91-97, 138-141, 139-141, 142-144; dL of IV-L: 114, 106, 156, 228, 232, 203. Figure 5. Hygrobates taiwanicus sp. n. ( A-B , D-E = female; C = male): A = coxal and genital field B-C = genital field (paratypes) D = chelicera E = palp. Scale bars = 100 µm . Figure 6. Hygrobates taiwanicus sp. n., female: A = I-L-2-6 B = IV-L. Scale bar = 100 µm . Etymology. The species is named for its occurrence in Taiwan. Remarks. The new Hygrobates species belong to the group of the species characterized byt the presence of two or three setae upon, and inside the margin of, the female pregenital sclerite and proximoventral seta on P-4 longer and thicker than distoventral seta. This group includes three species ( Matsumoto et al. 2005 ), all known only from middle Honshu (Japan), i.e., two lacustrine species, Hygrobates biwaensis Tuzovskij, 2003 and Hygrobates rarus Tuzovskij, 2003, which are known only from Lake Biwa, and one fluvial species, Hygrobates capillus Matsumoto Kajihara & Mawatari, 2005. Due to the elongate distoventral proj ection of P-2, Hygrobates taiwanicus sp. n. is most similar to Hygrobates biwaensis (in the following, in parentheses; data taken from Tuzovskij 2003 ) from which differs in the larger idiosoma dimensions (L 525-650 in both sexes), female genital plates longer (shorter) than gonopore, posterior end of female genital plates posterior (anterior) to postgenital sclerite and P-2 ventrodostal projection cone-shaped (more elongated and slender, finger-shaped). Distribution. Taiwan.