Eotrechus romglao, Vitheepradit, Akekawat & Sites, Robert W., 2007

Vitheepradit, Akekawat & Sites, Robert W., 2007, A review of Eotrechus Kirkaldy (Hemiptera: Heteroptera: Gerridae) of Thailand with descriptions of three new species, Zootaxa 1478, pp. 1-19 : 12-16

Eotrechus romglao sp. n.

Figs. 9–11 .

Description. WINGED MALE. Holotype, body length 7.39; width of head across eyes 1.56; maximum width across mesoacetabula 2.08. Paratypes (n = 7), body length 7.22–7.64 (mean = 7.43); width of head across eyes 1.56–1.60 (mean = 1.59); maximum width across mesoacetabula 2.00–2.08 (mean = 2.09). Dorsal coloration mainly black with numerous short, gold setae; brownish-yellow markings on lateral and posterior portions of head and medial and lateral portions of pronotum ( Figs. 9 a, b). Ventral coloration mainly brown except brownish-yellow head, prosternum, abdominal sternum VIII; dark brown metasternum and abdominal sterna II–VII; covered with numerous gold setae.

Head. Black with brownish-yellow markings as basal midline spot, pair of spots between antennal bases, pair of spots in front of eyes ( Figs. 9 a, b); length of head 1.16. Antennae brown, shorter than body, segment I with 4 spines on distal 1/6, lengths of segments I–IV = 2.08: 2.80: 2.00: 1.96. Eyes silvery-red, length of eye 0.72, synthlipsis 0.52. Rostrum mainly brownish-yellow, segment IV and midline of segment III black to dark brown, surpassing procoxae.

Thorax. Pronotum shorter than head (0.68: 1.16) with yellowish-brown elongate markings on midline and laterally behind eyes ( Fig. 9 a). Pronotal lobe entirely black; with shiny midline stripe and short, gold setae. Wings exceeding tip of abdomen; dark smoky-brown; costal margin and veins black; veins and some cells covered with short, gold setae; length of forewing along costal margin 5.64 ( Fig. 9 a). Pleura and acetabula mainly black, except propleuron with two brownish-yellow longitudinal stripes ( Fig. 9 b); silvery setae as large patches on pro- and mesoacetabula (viewed best with dry specimen), lateral surface of metacetabulum, ventral half of mesopleuron, and a thin longitudinal stripe in dorsal half of mesopleuron. Sterna mainly brown and covered with silvery pubescence, prosternum mostly yellowish-brown, mesosternum 2.78x length of metasternum (2.00: 0.72).

Legs. Mainly brownish-yellow. Fore femur with dark tip; brown longitudinal stripe on anterior margin; slightly incrassate with small tubercle near base ventrally ( Fig. 10 a); length 6.29x maximum width (2.64: 0.42); ventral surface with 6–7 stout, black hairs; basal tubercle with patch of dark setae. Fore tibia with long, dark brown setae; nearly straight except slightly curved distally; inner apical process blunt ( Fig. 10 a). Fore tarsus dark brown, covered with numerous dark brown setae. Middle, hind claws stout (length 0.18–0.20). Middle, hind legs with femora brownish-yellow with dark tips; thickened basally (width: 0.26, 0.22); slightly shorter than body length; covered with scattered stout, dark-brown setae. Middle and hind tibiae brownishyellow, covered with scattered stout, brown spines. Middle and hind tarsi dark brown, covered with numerous brown spines. Leg measurements as follows: foreleg, femur = 2.64, tibia = 2.44, tarsomere I = 0.20, tarsomere II = 0.40; middle leg, femur = 6.56, tibia = 6.31, tarsomere I = 0.40, tarsomere II = 0.42; hind leg, femur = 7.06, tibia = 7.22, tarsomere I = 0.38, tarsomere II = 0.40.

Abdomen. Tergites I–VII brown with median faint brown stripe, covered with gold setae on anterolateral corners of mediotergites. Tergite VIII brown with dark brown in distal half. Connexiva brown. Sterna II–VII length 2.44, with median brownish-yellow spots on anterior margins. Sternum VII shorter than combined lengths of sterna V and VI (0.38: 0.54), depressed medially and with deep concavity ( Figs. 9 c, 10b), with long brown setae on posterior margin ( Fig. 9 c). Sterna VIII and IX (genital segment) relatively large, length 1.04; sternum VIII with long brown setae laterally and posteriorly. Pygophore triangular with narrowly rounded tip; produced laterally into small knobs directed posterodorsad; covered with short, gold hairs laterally and posteriorly ( Figs. 10 b; 11a, b). Parameres small and blunt ( Fig. 11 a). Proctiger small, covered with long dark hairs on lateral surface of lateral wings and median lobe ( Figs. 11 c, d).

WINGED FEMALE. Allotype, length 8.38; width of head across eyes 1.64; width of thorax across mesoacetabula 2.32. Paratypes (n = 10) length, 7.97–8.55 (mean = 8.26); width of head across eyes 1.60–1.68 (mean = 1.64); width of thorax across mesoacetabula 2.16–2.32 (mean = 2.27). Similar to male in general structure and coloration with the following exceptions: Length of head 1.12; length of eye 0.76; synthlipsis 0.60. Antennae with 2–3 dark spines on distal 1/6 of segment I, length of segments: 1.76: 1.52: 1.28: 1.88. Pronotum proportionately shorter than head (0.70: 1.12). Length of forewing along costal margin 5.98. Mesosternum 2.59x length of metasternum (2.12: 0.82). Fore femur without proximal tubercle on ventral margin; with 11–15 stout, black hairs; length 7.88x maximum width (2.68: 0.34). Middle and hind claws stout (length: 0.18, 0.18). Middle and hind femora thickened basally (width: 0.28, 0.24). Leg measurements as follows: foreleg, femur = 2.68, tibia = 2.36, tarsomere I = 0.22, tarsomere II = 0.40; middle leg, femur = 6.64, tibia = 6.14, tarsomere I = 0.42, tarsomere II = 0.44; hind leg, femur = 6.81, tibia = 7.22, tarsomere I = 0.38, tarsomere II = 0.42. Tergite VIII dark brown on posterior margin. Abdominal sterna III–VII length 3.16. Sterna II–VI with median brownish-yellow spot on anterior margin. Sternum VII longer than combined lengths of sterna V and VI (1.00: 0.90), with hind margin straight. Genital segments 0.38, not concealed ( Fig. 10 c). Proctiger long with a roundly triangular posterior tip.

WINGLESS FORM. Unknown.

Diagnosis. Males of E. romglao can be distinguished from Thai congeners by the combination of a triangular pygophore with distinct, short, lateral projections. In contrast, E. elongatus has an elongate pygophore with a blunt tip, E. hygropetricus has a rounded pygophore, E. kalidasa has a pygophore with elongate posterolateral projections, E. petraeus has a triangular pygophore but without lateral projections, and E. siamensis has a stout pygophore with a bifid tip.

Females of E. romglao can be distinguished from those of E. hygropetricus and E. siamensis by the straight posterior margin of sternum VII, whereas those of latter species have a concave posterior margin. Females of E. romglao can be distinguished from those of E. kalidasa by the mesosternum almost three times as long as the metasternum, whereas in the latter species the mesosternum is less than twice as long as the metasternum ( Andersen 1982a). Females of E. romglao can be distinguished from E. elongatus by the ventral surface of head with a pair of dark brown stripes whereas in females of the latter species the ventral surface of the head is mainly dark brown. We have been unable to distinguish between females of E. romglao and E. petraeus .

Etymology. This species is named after the type locality of Romglao Waterfall in Phu Hin Rongkla NP.

Discussion. In the only key to species of Eotrechus ( Andersen 1982a) , E. romglao males key to the third couplet and females key to E. hygropetricus . The females of E. romglao and E. petraeus are indistinguishable based on discrete morphological structures, although females of E. romglao from Phetchabun Province are more slender and smaller than are females of E. petraeus from Chiang Mai Province. The type locality is a waterfall in the northeastern part of Phu Hin Rongkla NP, which is part of Phetchabun Mountain Range in Phitsanulok Province. More specifically, this new species occurred mainly on near-vertical rock surfaces at the sides of the waterfall, which were covered by moss and vegetation and occasionally splashed by water ( Fig. 2 ). The winged form of this species was collected from late dry season through early rainy season. This species occurred syntopically with E. elongatus . It has not been found at any other locality, including other waterfalls in Phu Hin Rongkla NP (i.e., Namtok Huai Kha Mheun, Namtok Mahn Dang, Namtok Palad, and Waterwheel Falls).

Material examined. Holotype, winged male, and allotype, winged female: THAILAND: Phitsanulok Prov.: Phu Hin Rongkla NP, Romglao Waterfall, 16°59'N 101°00'E, 1190 m, 6-V-2003, UMC and CMU teams, L-507. Paratypes, 7 winged males, 10 winged females, same data as holotype. 5 winged males, 1 winged females, same locality, 11-III-2002, R. W. Sites, A. Vitheepradit, K. Kirawanich, L-288; 11 winged males, 16 winged females, same locality, 22-IV-2002, CMU team; 1 winged male, 1 winged female, same locality, 22-IV-2002, N. Changthong; 2 winged females, same locality, 22-IV-2002, A. Nantakwang; 1 winged female, same locality, 17-III-2003, CMU team.

Additional material examined. 3 winged females, same data as holotype.

Figures

FIGURE 2. Type locality of Eotrechus elongatus and Eotrechus romglao at Romglao Waterfall, Phu Hin Rongkla NP.

FIGURE 9. Holotype of Eotrechus romglao. (a) Dorsal habitus; (b) head and pronotum, lateral view; (c) male abdomen, ventral view.

FIGURE 10. Eotrechus romglao. (a) left foreleg of male, inner aspect; (b) terminal abdominal segments of male, ventral view; (c) terminal abdominal segments of female, lateral view.

FIGURE 11. Eotrechus romglao male. (a) pygophore (p = parameres), dorsal view; (b) pygophore, lateral view; (c) proctiger, lateral view; (d) proctiger, dorsal view.