Eotrechus siamensis Vitheepradit & Sites, 2007

Tran, Anh Duc, Zettel, Herbert & Sites, Robert W., 2023, Revision of the genus Eotrechus Kirkaldy (Hemiptera, Heteroptera, Gerridae), with descriptions of six new species, Deutsche Entomologische Zeitschrift 70 (1), pp. 69-111 : 69

Eotrechus siamensis Vitheepradit & Sites, 2007

Figs 15F-I , 25

Eotrechus siamensis Vitheepradit & Sites, 2007: 2-8, figs 1, 3-6 (type locality: Doi Inthanon National Park, Chiang Mai Province, Thailand).

Eotrechus siamensis : Nakthong et al. (2014: 59, figs 39, 45) (key).

Material examined.

Holotype: Thailand • ♂ (apterous); Chiang Mai Province, Doi Inthanon National Park, Pha Dum waterfall, rock face; 18°36'N, 98°31'E; 1379 m a.s.l.; 3 May 2003; UMC and CMU teams leg.; L-499; UMC.

Paratypes: Thailand • 2 ♂♂, 3 ♀♀ (apterous) , 5 ♂♂, 4 ♀♀ (macropterous); same locality data as holotype; UMC • 1 ♂, 1 ♀ (macropterous); same locality data as holotype; ZRC • 4 ♀♀ (apterous); Chiang Mai Province, Doi Inthanon National Park, Siriphum Waterfall ; 18°32'N, 98°31'E, 1460 m a.s.l.; 2 Apr. 2002; UMC and CMU teams leg.; UMC .

Other material.

Thailand • 3 ♂♂, 1 ♀ (apterous) , 3 ♂♂, ♀ (macropterous); Chiang Mai Province, Doi Inthanon National Park, Siriphum waterfall; 24 Apr. 1995; D. Kovac leg.; DK#2/47; ZRC.6.19857; ZRC • 3 ♂♂ (macropterous); Chiang Mai Province, Doi Inthanon National Park, Siriphum waterfalls; 28 Apr. 1999; D. Kovac leg.; DK#A221/99; ZRC.6.19858; ZRC • 1 ♀ (apterous), 1 ♀ (macropterous); Chiang Mai Province, Doi Inthanon National Park, Siriphum waterfalls; 28 Apr. 1999; D. Kovac leg.; DK#A223/99; ZRC.6.19859; ZRC • 1 ♀ (apterous), 1 ♀ (macropterous); Chiang Mai Province, Doi Inthanon National Park, Siriphum Waterfall (upper); 18°32'N, 98°31'E; 1380 m a.s.l.; 2 Mar. 2002; Vitheepradit, Kirawanich leg.; UMC .

Diagnosis.

Size: apterous males, length 6.80-7.84, width 2.28-2.48; macropterous males, length 8.48-8.96, width 2.48-2.54; apterous females, length 7.60-7.76, width 2.44-2.68; macropterous females, length 8.80-9.84, width 2.32-2.72 (with additional data from Vitheepradit and Sites 2007). Venter of head with a median brown marking (in both sexes). Mesosternum ca. 2.8 × (in female) or 3.2 × (in male) length of metasternum. Male: fore femur incrassate, basal part broadened, with a large tubercle bearing a pointed tooth, distal part slightly constricted (Fig. 15F ); fore tibia almost straight with scattered, stiff setae on extensor side; abdominal sterna III-VI medially grooved; sternum VII broadly depressed, slightly longer than two sterna combined, posterior margin with a median notch about as deep as one-third of sternum VII length. Male genitalia (Fig. 15G-I ): abdominal segment VIII large, in ventral view, about as long as sternum VII, posterior margin on venter almost straight; pygophore short, posterolaterally with patch of very long, brush-like setae; caudal projection of pygophore plate-like with a concave posterior margin and angular posterolaterally; paramere small, ovoid; proctiger with pointed apex, directed upward, posterolateral lobes with patch of long, brush-like, brown setae, posteroventral surface without long, brush-like setae. Female: fore femur slender, flexor side with a row of ca. 15 long, stiff setae; fore tibia with scattered, long, stiff setae on extensor side along its length; sternum VII about as long as two preceding sterna combined, posterior margin almost straight, not enclosing genitalia; tergum VIII slightly tapering posteriorly; proctiger with acute apex.

Remarks.

This species can be placed in the E. pingae species group because it has a basal tubercle on the fore femur of the male, a median notch on posterior margin of the sternum VII of the male, a plate-like apical projection of the pygophore, and a tri-lobed proctiger. This species possesses some unique characteristics that distinguish it from all other species of Eotrechus : the basal tubercle of the fore femur of the male is modified into a pointed tooth and the caudal projection of the pygophore is uniquely crescent-shaped (distinctly concave posteriorly and angular posterolaterally). Colouration of venter of head seems to be a good character to distinguish females of this species from others in the E. pingae group. Otherwise, females of species in the E. pingae group are very similar to each other.

Distribution.

Thailand: Chiang Mai ( Vitheepradit and Sites 2007) (Fig. 25 ).

Figures

Figure 15. Eotrechus elongatus (A-E) and E. siamensis (F-I), males. A, B, F. Right fore leg (A, F. Ventral view; B. Dorsal view); C, G. Genital capsule, lateral view; D, H. Pygophore, dorsal view; E, I. Proctiger, dorsal view (A, B, F. Same scale; C-E, G-I. Same scale).

Figure 25. Distribution records of species of Eotrechus. Squares represent E. kalidasa species group; circles represent E. pingae species group; triangles represent species unassigned to a group.