Eotrechus petraeus Andersen

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 : 16-17

Eotrechus petraeus Andersen

Fig. 12 .

Eotrechus petraeus Andersen 1982a: 15 –16.

Supplemental description. WINGLESS FEMALE (n = 5). Similar to wingless male in general structure and coloration (see Andersen 1982a) with the following exceptions: Length, 7.64–8.05 (mean = 7.80); width of head across eyes 1.64–1.72 (mean = 1.69); width of thorax across mesoacetabula 2.08–2.36 (mean = 2.27); length of head 1.20; length of eye 0.76; synthlipsis 0.72. Antennae with 4 dark spines on distal 1/6, length of segments: 1.80: 1.68: 1.48: 2.04; Length of pronotum proportionately shorter than head (0.96: 1.20). Mesosternum 2.89x length of metasternum (2.12: 0.76). Fore femur without proximal tubercle on ventral margin; with 11–15 stout, black hairs; length 6.70x maximum width (2.68: 0.40). Middle and hind claws stout (length: 0.16, 0.16). Middle and hind femora thickened basally (width: 0.30, 0.24). Leg measurements as follows: foreleg, femur = 2.68, tibia = 2.48, tarsomere I = 0.32, tarsomere II = 0.44; middle leg, femur = 7.22, tibia = 7.06, tarsomere I = 0.48, tarsomere II = 0.46; hind leg, femur = 7.47, tibia = 8.47, tarsomere I = 0.40, tarsomere II = 0.46. Mediotergites III–VII with brownish-yellow, median longitudinal stripe. Tergite VIII with 2 sublateral dark stripes on basal 2/3. Sterna II–VII length 2.84 without median groove. Sternum VII longer than combined lengths of sterna V and VI (1.00: 0.80), with hind margin straight. Genital segments (VIII and IX) 0.44, not concealed (lateral view, Fig. 12 ). Proctiger long with triangular posterior tip.

WINGED FEMALE (n = 4). Similar to wingless female in general structure and coloration with the following exceptions: ventral surface darker, length 8.13–8.55 (mean = 8.32). Width of thorax across mesoacetabula 2.20–2.36 (mean = 2.27); width of head across eyes 1.60–1.64 (mean = 1.63). Pronotal lobe entirely black; with shiny midline stripe with short, gold setae. Wings exceeding tip of abdomen; dark smoky-brown; veins and some cells covered with short, gold setae; length of forewing along costal margin 5.81–5.98 (mean = 5.91).

WINGED MALE. Similar to wingless male in general structure and coloration with the following exceptions: Ventral surface slightly darker, length 7.55. Width of thorax across mesoacetabula 2.12; width of head across eyes 1.60. Pronotal lobe entirely black, with shiny midline stripe and short gold setae. Wings exceeding tip of abdomen; dark smoky-brown; veins and some cells covered with short, gold setae; length of forewing along costal margin 6.06.

Diagnosis. Males of E. petraeus can be distinguished by the acute posterior tip of the pygophore without 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. romglao has a triangular pygophore with distinct, short, lateral projections; and E. siamensis has a stout pygophore with a bifid tip.

Females of E. petraeus 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. petraeus can be distinguished from those of E. kalidasa by the mesosternum being almost three times longer than the metasternum, whereas in the latter species the mesosternum is less than twice as long as the metasternum ( Andersen 1982a). Females of E. petraeus can be distinguished from those of E. elongatus by the ventral side of head having a pair of dark brown stripes, whereas the latter species has the ventral side of head mainly dark brown. We have been unable to distinguish between females of E. romglao and E. petraeus .

Discussion. In the only key to species of Eotrechus ( Andersen 1982a) , females of E. petraeus key to E. hygropetricus . This species has been previously reported from Chiang Mai, Thailand ( Andersen 1982a). Here we add records from Doi Inthanon and Doi Suthep, Chiang Mai Province. This species occurred syntopically with E. hygropetricus and E. siamensis at Huay Sai Luang and Siriphum waterfalls in Doi Inthanon NP, and Sai Yoi Waterfall in Doi Suthep-Pui NP. Based on the extensive collecting in Thailand from 1998–2006, this species appears to be a local endemic and restricted to only Doi Inthanon and Doi Suthep in Chiang Mai Province.

Material examined. THAILAND: Chiang Mai Prov.: 10 wingless males, 2 wingless females, Doi Inthanon NP, Huay Sai Luang Waterfall, 18°31'N 98°27'E, 1060 m, 20-III-2002, R. W. Sites, A. Vitheepradit, K. Kirawanich, L-311; 1 wingless female, same locality, 4-IV-2002, UMC and CMU teams, L-322; 1 winged female, same locality, 8-V-2002, UMC and CMU teams, L-396; 1 wingless female, same locality, 11-VI-2002, CMU team; 1 winged female, same locality, 11-VIII-2002, CMU team; 1 wingless female, 1 winged female, same locality, 7-XII-2002, CMU team; 1 wingless male, same locality, 16-II-2003, CMU team; 1 wingless female, Doi Inthanon NP, Siriphum Waterfall, 18°32'N 98°31'E, 1380 m, 8-XII-2002, CMU team; 1 winged female, Doi Suthep-Pui NP, Sai Yoi Waterfall, 18°48'N 98°55'E, 1100 m, 24-IX-2002, CMU team; 1 winged male, same locality, 8-X-2002, CMU team; 1 winged male, 1 winged female, same locality, 11-I-2003, CMU team.

Figures

FIGURE 12. Terminal abdominal segments of female Eotrechus petraeus, lateral view.