Onychotrechus esakii Andersen

Nakthong, La-Au, Vitheepradit, Akekawat & Sites, Robert W., 2014, Key to the species of Eotrechinae (Hemiptera: Heteroptera: Gerridae) of Thailand and review of the fauna of the Phetchabun Mountain Range, Zootaxa 3860 (1), pp. 47-63 : 61

Onychotrechus esakii Andersen

Figs. 5 , 7

Onychotrechus esakii Andersen 1980 : Steenstrupia 127–128.

Diagnosis. This species can be recognized by the sublateral light stripes of the mesonotum reaching the mesonotal hind margins in the apterous form ( Fig. 5 ). It may be distinguished from congeners in Southeast Asia by the boldly contrasting and dark color pattern, whereas in O. pallidus Andersen (known from Malaysia), the pattern is reduced and color pale.

Discussion. This species has been recorded from China, Malaysia, Thailand, and Vietnam ( Andersen 1980; Zettel & Chen 1996; Cheng et al. 2001; Cheng et al. 2006). In Thailand, O. esakii has been recorded from waterfalls in northern, central, northeastern, and southern Thailand ( Andersen 1980, Vitheepradit 2000). This species, as well as its congeners, are typically found on rock surfaces in streams or rock walls splashed by waterfalls ( Andersen 1980, Vitheepradit 2000). In this study, this species is widespread throughout the mountain range.

Material examined. THAILAND: Chaiyaphum Province: Nam Nao NP, stream before Heaw Sai Waterfall, 16°40’N 101°41'E, 566 m, 5-V-2004, A. Vitheepradit, L-665 (1 wingless male); Loei Province: Amphur Phu Rua, Song Korn Waterfall, 17°21’N 101°24'E, 728 m, 10-V-2004, A. Vitheepradit and T. Prommi, L-676 (4 winged males, 4 wingless males, 1 winged female, 2 wingless females); Phu Rua NP, Sam Chan Waterfall, 17°29’N 101°20'E, 1147 m, 20-XII-2012, KU team, C-233 (10 winged males, 16 winged females); Phetchabun Province: Nam Nao NP, stream behind visitor center, 16°44'N 101°34'E, 820 m, 9-III-2002, A. Vitheepradit, L-275 (1 wingless female); Tad Mok NP, Song Nang Waterfall, 16°22’N 101°22'E, 800 m, 30-IV -2004, A. Vitheepradit, L- 654 (1 winged male); Nam Nao NP, Sum Ma Cow, 16°41'N 101°40'E, 562 m, 20-XII-2012, KU team, C-238 (1 wingless female); Phitsanulok Province: Phu Hin Rongkla NP, Waterwheel Fall and stream, 16°59’N 101°00'E, 1280 m, 10-III-2002, R.W. Sites, A. Vitheepradit, and K. Kirawanich, L-285 (1 winged female); Phu Hin Rongkla NP, Romglao Waterfall, 16°59’N 101°00'E, 1190 m, 11-III-2002, R.W. Sites, A. Vitheepradit and K. Kirawanich, L-288 (1 winged male, 1 winged female); Phu Hin Rongkla NP, Nam Tok Palad, 16°59’N 101°00'E, 300 m, 12-III- 2002, R.W. Sites, A. Vitheepradit and K. Kirawanich, L-289 (1 winged male); Phu Hin Rongkla NP, Huai Kha Mheun, 16°59’N 101°00'E, 1253 m, 6-V-2003, A. Vitheepradit and T. Prommi, L-505 (8 winged males, 1 wingless male, 6 winged females, 3 wingless females); Phu Hin Rongkla NP, Romglao Waterfall, 16°59’N 101°00'E, 1190 m, 6-V-2003, A. Vitheepradit and T. Prommi, L-507 (1 wingless female).

Figures

FIGURES 3 – 5. Genera of male Eotrechinae. (3) Amemboa, (4) Eotrechus, (5) Onychotrechus.

FIGURES 6 – 7. Distal leg segments showing pretarsal claws. (6) Eotrechus, (7) Onychotrechus.