Eotrechus thai, 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 thai sp. nov.

Figs 11 , 12 , 13B, F-I , 26

Eotrechus petraeus (non Andersen, 1982): Vitheepradit and Sites (2007: 16-17, fig. 12); Nakthong et al. (2014: 59, figs 37, 43) (key). Misidentifications.

Material examined.

Holotype: Thailand • ♂ (apterous); Chiang Mai Province, Doi Inthanon National Park, Huay Sai Luang waterfall, with stream; 18°31'N, 98°27'E; 1060 m a.s.l.; 20 Mar. 2002; Sites, Vitheepradit, Kirawanich leg.; L-311; UMC.

Paratypes: Thailand • 8 ♂♂, 1 ♀ (apterous); same locality data as for holotype; UMC • 1 ♂, 1 ♀ (apterous); same locality data as preceding; ZRC • 1 ♀ (apterous); same locality as for holotype; 4 Apr. 2002; UMC & CMU teams leg.; L-322; UMC • 1 ♀ (macropterous); same locality as preceding; 8 May 2002; UMC & CMU teams leg.; L-396; UMC • 1 ♂ (apterous); same locality data as preceding; NHMW • 1 ♀ (apterous); same locality as preceding; 9 Jun. 2002; CMU team leg.; UMC • 1 ♀ (macropterous); same locality as preceding; 11 Aug. 2002; CMU team leg.; UMC • 1 ♂ (apterous); same locality as preceding; 16 Feb. 2003; CMU team leg.; UMC • 1 ♀ (macropterous); same locality as preceding; 7 Dec. 2008; CMU team leg.; UMC • 1 ♀ (apterous); same locality data as preceding; NHMW • 1 ♂ (apterous); Doi Inthanon National Park, Namtok Siriphum ; 18°32'N, 98°31'E; 1460 m a.s.l.; 8 Dec. 2002; CMU team leg.; UMC • 1 ♀ (apterous), 1 ♀ (macropterous); Chiang Mai Province, Doi Suthep National Park, Namtok Sai Yoi ; 18°48'N, 98°55'E; 1100 m a.s.l.; 11 Jan. 2003; CMU team leg.; UMC • 1 ♂ (macropterous); same locality as preceding; 8 Oct. 2002; CMU team leg.; UMC • 1 ♀ (macropterous); same locality as preceding; 24 Sep. 2002; CMU team leg.; UMC • 1 ♀ (apterous), 1 ♂ (macropterous); Chiang Mai Province, Doi Inthanon National Park, Siriphum waterfalls; 24 Apr. 1995; D. Kovac leg.; ZRC.6.19855; ZRC .

Description.

Size: apterous males: length 6.48-6.80 (holotype 6.80), width 1.88-2.12 (holotype 1.96); macropterous male: length 8.40, width 2.12; apterous females: length 7.28-7.76, width 2.16-2.28; macropterous females: length 8.40-8.64, width 2.28-2.32.

Colour (Fig. 11 ): Dorsum generally dark-brown to black, covered with golden pubescence. Anterolateral sides and posterior margin of head with orange marks. Pronotum with three longitudinal orange stripes, one median and two sublateral, all not reaching posterior margin. Mesonotum mostly orange, with darkened transverse band near middle, deflecting posteriorly as paired, longitudinal, darkened stripes close to midline; posterior half with darker-orange suffusion. Propleuron black, with a longitudinal yellowish-orange stripe behind eye and yellowish area dorsad of black proacetabulum. Mesoacetabulum mostly black and metacetabulum black dorsally and orange ventrally. Proacetabulum, mesopleuron, meso- and metacetabula with patch of reflective silvery pubescence. Antennae brown. All legs chiefly yellowish-brown. Venter of head and prosternum mainly yellowish. Mesosternum mostly yellowish with light-brown suffusion and indistinct median and lateral longitudinal stripes; metasternum varying from yellowish-brown to dark reddish-brown. Abdominal sterna orangish-brown, darker brown dorsally just ventrad of terga.

Structural characteristics: Apterous male (holotype): Head width across eyes 1.54; interocular width 0.54; eye kidney-shaped in dorsal view, length of eye 0.73. Antennae 6.56 and subequal to body length, lengths of segments I-IV: 1.60: 1.80: 1.40: 1.76; segment I with four spines subapically. Pronotum broader than long, shorter than head length (0.90: 1.14). Lengths of mesosternum and metasternum: 1.92 and 0.60. Lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II) as follows: fore leg: 2.56: 2.56: 0.26: 0.36; middle leg: 6.72: 6.64: 0.40: 0.38; hind leg: 6.88: 7.68: 0.32: 0.44. Fore leg (Fig. 13B ): trochanter with two long, fine setae; femur incrassate, length ca. 5.4 × maximum width (2.56: 0.47), with a large basal tubercle bearing a round, small, tuberculate spot with black, minute setae, then gradually tapering towards apex, along flexor side of femur with a row of seven long stiff setae; tibia almost straight, slightly narrower at distal part, with scattered, stiff setae on extensor side and some shorter stout setae on apical margin; tarsus covered with long, soft, yellowish setae (denser on ventral surface). Middle and hind femora slender and slightly longer than body; middle and hind femora, middle and hind tibiae with scattered, short, brown spines. Claws stout, lengths of fore, mid- and hind claws: 0.12: 0.10: 0.14. Abdomen short, total length of abdominal sterna II-VII: 1.40, sterna II-VI not medially grooved. Sternum VII slightly longer than length of two preceding sterna combined (0.34: 0.44), broadly depressed, posterior margin with a large median notch about as deep as two-fifths of the length of sternum VII (Fig. 12C ). Genitalia (Figs 12 , 13G-I ): abdominal segment VIII large, ventral side distinctly longer than sternum VII, posterior margin with dense, yellowish setae; pygophore with small lateral tubercles bearing a tuft of yellowish setae, caudal projection triangular, directed dorsad, about as long as main body of pygophore; paramere ovoid; proctiger with lateral tubercle bearing long, brown setae, ventral surface with a patch of brown, brush-like setae.

Apterous female: Head width across eyes 1.58; interocular width 0.60; eye kidney-shaped in dorsal view, length 0.74. Antennae ca. 0.8 × of body length (6.08: 7.28), lengths of segments I-IV: 1.68: 1.48: 1.28: 1.64; segment I with 3 dark spines subapically (other shorter spines apically). Pronotum shorter than head length (0.88: 1.24). Lengths of mesosternum and metasternum: 2.04 and 0.68. Lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II): fore leg: 2.56: 2.32: 0.26: 0.36; middle leg: 6.72: 6.64: 0.40: 0.42; hind leg: 7.04: 7.84: 0.42: 0.40. Fore trochanter with one long, fine seta on ventral side (seta length subequal to width of trochanter). Fore femur moderately incrassate, length ca. 7.1 × maximum width (2.56: 0.36), without tubercle at basal part, moderately thickened at basal part and gradually tapering towards apex, along flexor side with a row 14-15 long, stiff setae, all shorter than greatest width of fore femur. Fore tibia straight, with many long, stout setae on extensor surface and some shorter, stout setae on apical margin. Fore tarsus covered with long, soft, yellowish setae (denser on ventral surface). Middle and hind femora slender and shorter than body length; middle and hind femora, middle and hind tibiae with scattered short, brown spines. Claws stout, lengths of fore, mid- and hind claws: 0.12: 0.16: 0.15. Total length of abdominal sterna II-VII ca. 0.36 × body length (2.64: 7.28). Sternum VII 1.2 × length of two preceding sterna combined (0.92: 0.76), posterior margin almost straight. Connexival apex of sternum VII truncate, slightly curved mesad, and lateral and ventral surfaces of sternum VII set with a few long, golden setae interspersed by short, golden setae. Genitalia: not concealed by sternum VII; tergum VIII constricted on posterior part then produced posterolaterally; proctiger elongate, with pointed apex and directed caudad (Fig. 13F ).

Macropterous male: Similar to apterous male but with following differences: Pronotum wider, longer, dark reddish-brown, with reddish midline ridge; wings chiefly medium-brown with light-brown patches, reddish-brown veins, four closed cells, and linear series of golden setae, membrane yellowish-brown. Pronotum length (including posterior lobe) 2.88, humeral width 1.80. Fore wing length 5.36.

Macropterous female: Colouration similar to macropterous male. Pronotum length (including posterior lobe) 2.88, humeral width 1.91. Fore wing length 5.28. Other characteristics similar to apterous female.

Remarks.

Specimens of this new species, collected near the type locality of E. petraeus , were previously determined as E. petraeus by Vitheepradit and Sites (2007). The pygophore of this species also has a triangular caudal projection, but it is much shorter than that of E. petraeus .

This new species is more closely related to E. romglao by sharing similarities in the fore femur of the male (with basal spot of black minute setae), the notched posterior margin of male sternum VII, and the male genitalia (pygophore with a triangular caudal projection, similar shape of proctiger). However, males of E. thai sp. nov. can be distinguished from those of E. romglao by the following: the fore femur has a distinct broad tubercle with a rounded spot of minute, black setae (in E. romglao : the basal tubercle is indistinct and the spot of minute, black setae is present, but much smaller); the abdominal sternum is not medially grooved (in E. romglao : it is medially grooved from sterna III-VI); abdominal segment VIII, in ventral view, is longer than sternum VII (in E. romglao , segment VIII is subequal in length to sternum VII); the lateral tubercles of the pygophore are less developed; the caudal projection of the pygophore is longer and with a pointed apex (in E. romglao : the lateral tubercles are much more prominent and subtriangular, and the caudal projection is shorter, with a narrowly rounded apex).

Females of these two species are different only in colouration of the venter of the head: in E. thai sp. nov., it is mainly yellow, whereas in E. romglao , it has a pale background with dark-brown markings. Otherwise, females are indistinguishable.

Etymology.

The specific epithet is in reference to the country of Thailand and to the warm, friendly Thai people.

Distribution.

Thailand: Chiang Mai (Fig. 26 ).

Eotrechus pingae species group

Diagnosis. Male: fore femur with a large basal tubercle, which usually bears a small patch of minute black setae, or produced into a nodule bearing minute black setae, or produced into a pointed tooth-like elevation; posterior margin of sternum VII medially notched, about one-third the length of sternum VII; abdominal segment VIII relatively long; pygophore usually with lateral tubercles bearing long setae; caudal projection of pygophore relatively flat, with broad apical margin; proctiger with angular apex and usually with two posterolateral lobes; lateral or ventral side of proctiger usually bearing long setae. Female: tergum VIII simple; sternum VII about as long as two preceding sterna combined.

Species included. E. pingae Andersen, 1998, E. luaae Tran & Zettel, 2006, E. elongatus Vitheepradit & Sites, 2007, E. fansipan J. Polhemus, Tran & D. Polhemus, 2009, E. siamensis Vitheepradit & Sites, 2007, and E. konkakinh sp. nov.

Figures

Figure 11. Eotrechus thai sp. nov., habitus. A. Apterous male (from Doi Inthanon. Thailand); B. Apterous female (from Doi Inthanon); C. Macropterous female (from Doi Suthep, Thailand).

Figure 12. Eotrechus thai sp. nov., male genitalia. A. Lateral view; B. Dorsal view; C. Ventral view.

Figure 13. Eotrechus romglao (A, C-E) and E. thai sp. nov. (B, F-I). A, B. Right fore leg, ventral view; C, G. Genital capsule (pygophore and proctiger) of male, lateral view; D, H. Pygophore, dorsal view; E, I. Proctiger, dorsal view; F. Abdominal apex of female, dorsal view (A, B. Same scale; C-E, G-I. Same scale).

Figure 26. Distribution records of species of Eotrechus. Circles represent E. longipes species group; squares represent E. petraeus species group; stars represent E. vietnamensis species group.