Eotrechus elongatus, 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 : 8-12

Eotrechus elongatus sp. n.

Figs. 6–8 .

Description. WINGED MALE. Holotype, body length 8.38; width of head across eyes 1.68; maximum width across mesocetabula 2.48. Paratypes (n = 10), body length 7.97–8.55 (mean = 8.31); width of head across eyes 1.64–1.72 (mean = 1.68); maximum width across mesocetabula 2.36–2.48 (mean = 2.41). Dorsal coloration mainly black with numerous short, gold setae; brownish-yellow markings on lateral and posterior portions of head, medial portion of pro- and mesonotum, anterolateral and medial portions of pronotum ( Figs. 6 a–c). Ventral coloration mainly brown except brownish-yellow head, prosternum, abdominal sterna VII–VIII; dark brown metasternum and abdominal sterna II–VI; covered with numerous gold setae.

Head. Black with brownish-yellow basal band and lateral markings in front of eyes ( Figs. 6 a, b); length of head 1.12. Antennae dark brown, shorter than body, segment I with 5–6 dark spines on distal 1/6, lengths of segments I–IV = 2.08: 1.80: 1.28: 1.84. Eyes silvery-red, length of eye 0.72, synthlipsis 0.66. Rostrum mainly brownish-yellow, segment IV and midline of segment III black to dark brown, surpassing procoxae.

Thorax. Pronotum shorter than head (0.80: 1.12); with yellowish-brown midline stripe and anterolateral markings ( Fig. 6 a); posterior 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 6.06. Pleura and acetabula mainly black, except propleuron with two brownish-yellow longitudinal stripes ( Fig. 6 b); silvery setae as large patches on pro- and mesoacetabula (viewed best with dry specimen), lateral surface of metacetabulum, ventral half of mesopleuron, and thin longitudinal stripe in dorsal half of mesopleuron. Prosternum mostly yellowish-brown. Meso- and metasterna entirely black, covered with silvery pubescence, mesosternum 2.66x length of metasternum (2.08: 0.78).

Legs. Mainly brownish-yellow. Fore femur with brown stripe on anterior margin and brown patch on middle of posterior margin; moderately incrassate in proximal 1/4 followed by excavation with proximal hair tuft but no tubercle on ventral margin ( Fig. 7 a); length 4.96x maximum width (2.96: 0.60); ventral surface with 7– 8 stout, black hairs; basal tubercle with patch of small brown bristles. Fore tibia almost straight except slightly curved distally with long, stout, dark brown setae; inner apical process blunt. Fore tarsus dark brown, covered with numerous dark brown setae. Claws stout (length 0.24–0.26). Middle and hind legs with femora brown; thickened basally (0.32, 0.28); slightly shorter than body length; covered with scattered, stout, brown spines. Tibiae becoming darker distally, covered with scattered, stout, dark brown spines becoming more dense distally. Tarsi dark brown, covered with numerous dark brown spines on inner surface, becoming obsolete distally on tarsomere II. Leg measurements as follows: foreleg, femur = 2.96, tibia = 2.80, tarsomere I = 0.28, tarsomere II = 0.52; middle leg, femur = 7.80, tibia = 6.97, tarsomere I = 0.56, tarsomere II = 0.62; hind leg, femur = 7.64, tibia = 8.30, tarsomere I = 0.60, tarsomere II = 0.68.

Abdomen. Tergites I–VII dark, IV–VII with median faint brown stripe; VIII mostly dark brown and covered with long golden-brown setae. Connexiva entirely dark. Sterna II–VII length 1.72, with median brownish-yellow spots on anterior margin of III and VII. Sternum VII with broad, inverted-U shaped depression; shorter than combined lengths of sterna V and VI (0.46: 0.52), with broad angular notch on posterior margin ( Figs. 6 c, 7b) with long brown setae ( Fig. 6 c). Sterna VIII and IX (genital segment) large, length 1.60. Sternum VIII with triangular depression on anterior margin and broad depression in posterior 2/3, with long, golden-brown setae; posterolateral margins convergent, tuberculate medially ( Fig. 6 c). Pygophore elongate; tuberculate medially; posteriorly produced into an elongate tongue-like shape ( Figs. 7 b; 8a, b); covered with long, stout, golden-brown setae laterally ( Figs. 8 a, b). Parameres short, stout ( Fig. 8 a). Proctiger trilobed with median lobe raised (lateral view, Fig. 8 c); tips of lateral wings of proctiger not surpassing tip of median lobe (dorsal view, Fig. 8 d); posteroventral surface covered with long, dark brush of hairs; length of hairs about 1/2 length of proctiger ( Fig. 8 c).

WINGED FEMALE. Allotype, length 9.13; width of head across eyes 1.68; width of thorax across mesoacetabula 2.64. Paratypes (n = 10) length, 8.08–9.13 (mean = 8.96); width of head across eyes 1.68–1.80 (mean = 1.72); width of thorax across mesoacetabula 2.64–2.72 (mean = 2.69). Similar to male in general structure and coloration with the following exceptions: length of head 1.40; length of eye 0.74; synthlipsis 0.66. Antennae with 6–7 dark spines on distal 1/6 of segment I, length of segments: 1.88: 1.68: 1.24: 1.80. Pronotum proportionately shorter with respect to head (0.86: 1.40). Forewing length along costal margin 6.64. Mesosternum 1.83x length of metasternum (2.24: 1.22). Fore femur without proximal tubercle on ventral margin, with 15–18 black stout hairs, length 6.95x maximum width (2.92: 0.42). Middle and hind claws stout (length: 0.20, 0.22). Middle and hind femora thickened basally (width: 0.32, 0.26). Leg measurements as follows: foreleg, femur = 2.92, tibia = 2.48, tarsomere I = 0.28, tarsomere II = 0.52; middle leg, femur = 7.72, tibia = 6.81, tarsomere I = 0.66, tarsomere II = 0.66; hind leg, femur = 7.06, tibia = 8.05, tarsomere I = 0.70, tarsomere II = 0.66. Mediotergites I–VII with brownish-yellow median stripe. Tergite VIII brown with dark brown spots on posterior tip. Connexiva dark on inner margin. Sterna II–VII length 3.40, with median brownish-yellow spot on anterior margin of II. Sterna IV–VI with brownish-yellow longitudinal stripe. Sternum VII longer than combined lengths of sterna V and VI (1.14: 0.98), with hind margin straight. Genital segments 0.40, not concealed ( Fig. 7 c). Proctiger long with roundly triangular posterior tip.

WINGLESS MALE. Length 7.89; width of head across eyes 1.64; width of thorax across mesoacetabula 2.28. Similar to winged male in general structure and coloration with the following exceptions: Mesonotum with brownish-yellow midline stripe and broad U-shaped marking along margins in posterior 1/2. Ventral coloration mainly dark brown, except abdominal sterna VII–VIII and genital segment brownish-yellow. Abdominal sterna II–VI with broad, brownish-yellow midline band. Fore femur with 7–9 stout, black hairs. Tergites I–VII with a faint median stripe becoming more pronounced posteriorly.

WINGLESS FEMALE. Unknown.

Diagnosis. This species can be recognized by an elongate pygophore with a blunt tip in the males. Males of E. elongatus can be distinguished by the angular posterior margin of abdominal sternum VIII, whereas those of Thai congeners have a straight posterior margin. Females of E. elongatus 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. elongatus can also be distinguished from those of E. kalidasa by the mesosternum being approximately twice 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. elongatus can be distinguished from those of E. petraeus and E. romglao by the ventral side of head being mainly dark brown, whereas those of the latter species have a pair of dark stripes.

Etymology. This species is named elongatus because the male pygophore is relatively long.

Discussion. In the only key to species of Eotrechus ( Andersen 1982a) , E. elongatus males key to E. petraeus , although the pygophore of E. elongatus does not match the supporting illustrations, and females key to E. hygropetricus . Males of E. elongatus and E. luaae Tran & Zettel from China ( Tran & Zettel 2006) share similar genitalic structure. They differ in that males of E. elongatus have the posterior tip of the lateral wings of the proctiger not surpassing the central lobe of the proctiger (when viewed dorsally) and reaching only the middle part of the pygophore (when viewed ventrally), whereas males of E. luaae have the posterior tip of the lateral wings of the proctiger surpassing the central lobe of the proctiger (when viewed dorsally) and the middle part of the pygophore (when viewed ventrally). The type locality is a waterfall in the northeastern part of Phu Hin Rongkla NP, which is part of the Phetchabun Mountain Range in Phitsanulok Province. More specifically, this new species occurred mainly on the rock surfaces at the sides of the waterfall, which were occasionally splashed by water and covered by moss and vegetation ( Fig. 2 ). This species was also collected from a similar habitat at another waterfall in the northern part of Phu Hin Rongkla NP Specimens of the winged form were found nearly throughout the year at the type locality. This species occurred syntopically with E. romglao at Romglao Waterfall in Phu Hin Rongkla NP.

Material examined. Holotype, wingless male, and allotype, wingless female: THAILAND: Phitsanulok Prov.: Phu Hin Rongkla NP, Romglao Waterfall, 16°59'N 101°00'E, 1190 m, 6-V-2003, A. Vitheepradit, T. Prommi, M. Ferro, L-507. Paratypes, 10 winged males, 10 winged females, same data as holotype; 1 wingless male, same locality, 23-VIII-2002, CMU team.

Additional material examined. THAILAND: Phitsanulok Prov.: Phu Hin Rongkla NP, Romglao Waterfall, 16°59'N 101°00'E, 1190 m, 11-III-2002, 6 winged males, 3 winged females, R. W. Sites, A. Vitheepradit, K. Kirawanich, L-288; 3 winged males, 1 winged female, same locality, 22-IV-2002, CMU team; 1 winged male, same locality, 22-IV-2002, N. Changthong; 1 winged male, same locality, 22-IV-2002, A. Nantakwang; 13 winged males, 12 winged females, same locality, 22-V-2002, CMU team; 1 winged female, same locality, 21-VI-2002, CMU team; 1 winged male, same locality, 23-VIII-2002, CMU team; 1 winged male, 2 winged females, same locality, 28-IX-2002, CMU team; 1 winged male, 1 winged female, same locality, 21-X-2002, CMU team; 3 winged females, same locality, 15-XI-2002, CMU team; 2 winged males, 2 winged females, same locality, 15-XII-2002, CMU team; 2 winged males, 1 winged female, same locality, 17-III-2003, CMU team; 7 winged males, 6 winged females, same locality, 10-IV-2003, CMU team; 2 winged males, 4 winged females, same locality, 4-V-2003, CMU team; 1 winged male, same data as holotype; Loei Prov.: Phu Hin Rongkla NP, Man Daeng Waterfall, tier 5, 16°57'N 101° 03'E, 1250 m, 11-III-2002, G. W. Courtney.

Figures

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

FIGURE 6. Holotype of Eotrechus elongatus. (a) Dorsal habitus; (b) head and pronotum, lateral view; (c) male abdomen, ventral view.

FIGURE 7. Eotrechus elongatus. (a) left foreleg of male, inner aspect; (b) terminal abdominal segments of male, ventral view; (c) terminal abdominal segments of female, lateral view.

FIGURE 8. Eotrechus elongatus male. (a) pygophore (p = parameres), dorsal view; (b) pygophore, lateral view; (c) proctiger, lateral view; (d) proctiger, dorsal view.