Eotrechus steineri, Tran & Zettel & Sites, 2023

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 steineri sp. nov.

Figs 3 , 4D-F , 5A-E , 25

Eotrechus kalidasa (non Kirkaldy, 1902): Vitheepradit and Sites (2007: 18-19) (diagnosis, notes); Nakthong et al. (2014: 59-60, fig. 42) (key, diagnosis, notes). Misidentifications.

Material examined.

Holotype: Laos • ♂ (apterous); Vieng Phoukha , Tham Kuat (F47-119/010); 20°45.950'N, 101°0.828'E; 10 Feb. 2006; H. Steiner leg.; 132/06; N-Lao-Europ. Cave Project 2006; NHMW.

Paratypes: Laos • 3 ♂♂, 2 ♀♀ (apterous); same locality data as holotype; NHMW • 1 ♀ (apterous); Luang Prabang, Tham Suea, Tham Nam Lot; 19°26.928'N, 102°26.157'E; 3 Feb. 2005; H. Steiner leg.; 069/05; N-Lao-Europ. Cave Project 2005; NHMW • 1 ♀ (apterous); Luang Nam Tha Province, Vieng Phoukha; Tham A Pa (F47-119-026); 20°49.843'N, 101°3.733'E; 18 Jan. 2012; H. Steiner leg.; 027/12; Northern Lao-European Cave Project 2012; NHMW • 1 ♀ (apterous); Luang Nam Tha Province, Vieng Phouka, Um Chuck Njet (F47-119-029); 20°43.367'N, 101°0.963'E; 19 Jan. 2012; H. Steiner leg.; 138/12; Northern Lao-European Cave Project 2012; NHMW .

Thailand • 1 ♂ (macropterous); Loei Province, Phu Hin Rongkla National Park, Man Daeng Noi at trail; 16°57'N, 101°03'E; 1600 m a.s.l.; 21 Sep.-21 Oct. 2002; coll: CMU team, leg.; Eotrechus kalidasa Kirkaldy, det Vitheepradit 2005; UMC • 1 ♂ (macropterous); Nan Province, Namtok Sa Pan , stream with waterfall; 19°11.403'N, 101°11.850'E; 532 m a.s.l.; 17 Apr. 2009; Sites, Vitheepradit, Prommi leg.; L-1043; Eotrechus kalidasa , det Vitheepradit 2017; UMC .

Description.

Size: apterous males, length 9.25-9.75 (holotype 9.25), width 2.07-2.28 (holotype 2.12); macropterous male, length 10.32, width 2.12; apterous females, length 9.92-10.50, width 2.25-2.36.

Colour (Fig. 3 ). Apterous form, dorsum of body chiefly brown to dark-brown or black, with yellow markings on head and thorax, covered with golden pubescence; venter chiefly pale-brown. Head with two lateral yellow marks at anterior section and a transverse yellow mark on posterior margin. Antennae yellowish-brown to brown. Pronotum with a yellow midline stripe. Mesonotum with yellow midline stripe thinner posteriorly and usually not reaching posterior margin. Metanotum and abdominal tergum mainly without yellow marking. Propleuron with a longitudinal yellow stripe. Meso- and metapleura black, without yellow marking. All pleura covered with golden pubescence. All coxae chiefly light-coloured (usually light-yellowish); all other leg segments yellowish-brown to brown; apical parts of all femora dark-brown to black.

Structural characteristics: Apterous male (holotype): Head width across eyes 1.76; interocular width 0.69; eye kidney-shaped in dorsal view, length of eye 0.76. Antennae ca. 1.1 × body length (9.94: 9.25), lengths of segments I-IV: 2.64: 2.46: 2.25: 2.59; segment I without black spines. Pronotum broader than long, shorter than head length (1.17: 1.45). Posterior two-thirds of mesonotum strongly swollen, forming a hump. Lengths of mesosternum and metasternum: 1.81 and 1.17. Lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II) as follows: fore leg: 3.86: 2.91: 0.52: 0.48; middle leg: 6.50: 6.67: 0.41: 0.49; hind leg: 7.25: 8.50: 0.40: 0.48. Fore leg (Fig. 5A ): trochanter with one or two long, fine setae; femur slender, length ca. 11.4 × maximum width (3.86: 0.34), proximal part slightly thicker distal part, flexor side with few long, fine setae about evenly spaced along its length; tibia straight, without short, stout setae on distal third; tarsus covered with dense, short, soft, yellowish setae (denser on ventral surface). Middle and hind femora slender and shorter than body; middle and hind femora with scattered short, stout setae on ventral surface; middle and hind tibiae with very long, stout setae scattered along their lengths. Claws stout, lengths of fore, mid- and hind claws: 0.18: 0.22: 0.21. Abdomen relatively long, total length of abdominal sterna II-VII: 3.06, sterna II-VII weakly depressed medially, not forming distinct groove, depression on sternum VII widened posteriorly. Sternum VII ca. 0.66 × the length of two preceding sterna combined (0.63: 0.96), posterior margin with shallow median notch (ca. 0.15 × the length of sternum VII) (Fig. 5B ). Genitalia (Figs 4D-F , 5B, E ): ventral length of abdominal segment VIII: 0.41. Pygophore with two long, relatively slender posterolateral projections which curve dorsad. Paramere long, with proximal third wider, ca. 2.0 × as wide as distal part; distal part slender, directed slightly dorsad, apex rounded. Proctiger simple, longer than wide, with broadly rounded apex, posterolaterally slightly produced as broad processes.

Apterous female: Head width across eyes 1.89; interocular width 0.75; eye kidney-shaped in dorsal view, length 0.82. Antennae subequal to body length (10.33: 10.50), lengths of segments I-IV: 2.69: 2.51: 2.36: 2.77; segment I without black spines. Pronotum shorter than head length (1.17: 1.55). Posterior two-thirds of mesonotum strongly swollen, forming a hump. Lengths of mesosternum and metasternum: 1.99 and 1.37. Lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II): fore leg: 3.97: 3.06: 0.65: 0.52; middle leg: 6.83: 6.96: 0.44: 0.53; hind leg: 7.42: 8.83: 0.45: 0.54. Fore trochanter with two or three long, fine setae on ventral side. Fore femur similar to males, length ca. 11.3 × maximum width (3.97: 0.35). Fore tibia similar to males. Middle and hind legs similar to males. Claws stout, lengths of fore, mid- and hind claws: 0.21: 0.22: 0.23. Total length of abdominal sterna II-VII ca. 0.46 × body length (4.82: 10.5). Sternum VII ca. 0.75 × length of two preceding sterna combined (1.17: 1.55), posterior margin straight. Connexival corners of sternum VII broadly rounded. Genitalia almost completely concealed by abdomen in lateral view, only tip of proctiger visible, proctiger broader than long, directed ventrad (Fig. 5C, D ).

Macropterous male: Similar to apterous male but with following differences: Head ground colour dark-brown to black, with orange markings at middle of posterior margin and at anterodorsal margin of eye extending halfway to base of antenna; pronotum dark-brown to black, with orange longitudinal stripe on midline; propleuron with orange longitudinal stripe posterior to eye; wings chiefly dark-brown with medium-brown patches, reddish-brown veins, and linear series of golden setae. Pronotum length (including pronotal lobe) 3.08, humeral width 1.92. Fore wing length 6.52, wing veins similar to E. kalidasa (see Matsuda 1960: fig. 553; Andersen 1982: fig. 8).

Macropterous female: Unknown.

Etymology.

This species is dedicated to the German speleologist Dr Helmut Steiner who discovered it during one of his expeditions to northern Laos.

Remarks.

Eotrechus steineri sp. nov. can be separated from E. kalidasa and E. fuscus by the structure of the paramere, the relative lengths of the antennal segments, and the relative lengths of the fore tarsal segments. This new species can also be recognised by the large hump on the mesonotum. A mesonotal hump is also present in E. fuscus , but is much less conspicuous than that of this new species. Detailed differences between the three species are summarised in Table 1 .

Distribution.

Laos: Luang Nam Tha, Luang Prabang; Thailand: Loei (the specimen from Thailand reported as E. kalidasa by Vitheepradit and Sites (2007) belongs to this new species) (Fig. 25 ).

Eotrechus petraeus species group

Diagnosis. Male: fore femur incrassate, usually with a large basal tubercle bearing a spot of black, minute setae, or only with a spot of black, minute setae without distinct basal tubercle; posterior margin of sternum VII medially notched, about two-fifths of sternum VII length; pygophore with lateral tubercles with long setae; caudal projection of pygophore subtriangular or elongate with pointed apex; proctiger laterally bearing long setae, posterolaterally with round lobes or pointed processes, apex of proctiger angular. Female: tergum VIII usually produced posterolaterally; sternum VII about as long as two preceding sterna combined.

Species included. E. petraeus Andersen, 1982, E. kerberos sp. nov., E. romglao Vitheepradit & Sites, 2007, and E. thai sp. nov.

Figures

Figure 3. Eotrechus steineri sp. nov., habitus. A. Apterous male; B. Apterous female.

Figure 4. Eotrechus kalidasa, specimen from India (A-C) and E. steineri sp. nov. (D-F). A, D. Pygophore, lateral view; B, E. Proctiger, dorsal view; C, F. Paramere, lateral view (A, B, D, E. Same scale; C, F. Same scale).

Figure 5. Eotrechus steineri sp. nov. (A-E) and E. kalidasa (F). A. Fore leg of male; B. Abdomen of male, ventral view; C, D. Posterior part of abdomen of female, dorsal and lateral views; E, F. Paramere, lateral view (B-D. Same scale; E, F. 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.