Eotrechus anderseni, 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 anderseni sp. nov.

Figs 20B , 22 , 26

Material examined.

Holotype: India • ♂ (macropterous); Meghalaya State (10), E Khasi Hills, 11 km SW Cherrapunjee, Laitkynsew, seepage, wet rocks with algae/blue algae/moss, exposed, ca. 1.5-2 km via road from "Cherapunjee Holiday Resort" in direction Cherapunjee ; 25°13'N, 91°39'E; 810 m a.s.l.; 21-24 Apr. 2008; Fikáček, Podskalská & Šípek leg.; ZSM.

Paratypes: India • 1 ♀ (macropterous); same locality data as holotype; ZSM • 1 ♀ (macropterous); same locality data as holotype; NHMW • 1 ♀ (macropterous); same locality data as holotype; NMPC .

Description.

Size: macropterous male (holotype), length 10.45, width 2.81; macropterous females, length 10.70-11.25, width 3.01-3.15.

Colour (Fig. 20B ): Dorsal side of head largely black, ventral side with broad median black stripe. Dorsal side of pronotum only with yellow midline and sides, without yellow sublateral stripes, but with a pair of shiny stripes at this position. Wings mostly black with dark-brown patches, membrane dark-greyish. Venter of thorax and abdomen chiefly black, sterna V-VII medially yellow.

Structural characteristics: Macropterous male (holotype): Head width across eyes 1.76; interocular width 0.76; eye kidney-shaped in dorsal view, length of eye 0.83. Antennae: length 8.94, and shorter than body length, lengths of segments I-IV: 2.65: 2.61: 1.60: 2.08; segment I with one short spine subapically. Pronotum length 3.52, humeral width 2.03; pronotal lobe with median carina in anterior half. Fore wing length 6.36. Lengths of mesosternum and metasternum: 2.65 and 0.95. Lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II) as follows: fore leg: 3.23: 2.86: 0.36: 0.57; middle leg: 8.50: 7.65: 0.61: 0.78; hind leg: 8.90: 9.29: 0.67: 0.82. Fore leg (Fig. 22A ): trochanter without long, fine setae; femur moderately incrassate, length ca. 5.5 × maximum width at basal part (3.23: 0.59), distal part gradually tapering towards apex, without long, stiff setae along flexor side of femur; tibia almost straight, simple, with short, stout setae on apical third of extensor side; tarsus covered with long, brown setae on ventral surface, and only with short setae on dorsal surface. Middle and hind femora slender and shorter than body length; middle and hind femora, middle and hind tibiae with scattered, short, brown spines in distal parts. Claws moderately stout, lengths of fore, mid- and hind claws: 0.22: 0.30: 0.28. Abdomen short, total length of abdominal sterna II-VII: 3.51, sterna II-V medially not grooved. Sternum VI with narrow median impression. Sternum VII shorter than length of two preceding sterna combined (0.50: 0.82), triangularly depressed, posterior margin broadly and deeply emarginated, and with fringe of setae (Fig. 22B ). Genitalia (Fig. 22C-E ): abdominal segment VIII large, ventral side distinctly longer than sternum VII (0.73: 0.50), posterolaterally with dense, yellowish, soft setae; pygophore with thick posterolateral projections, apex of projection rounded, and distal part of projection swollen, covered with dense, long, bristle-like setae directed laterad; paramere simple, length about three times as width; proctiger simple, longer than wide, with narrowly rounded apex.

Macropterous female: Head width across eyes 1.97; interocular width 0.81; eye kidney-shaped in dorsal view, length 0.86. Antennae 0.64 × body length (7.16: 11.25), lengths of segments I-IV: 2.10: 2.08: 1.25: 1.73; segment I with one short, dark, subapical spine. Pronotum length 3.73, humeral width 2.37. Fore wing length 7.30. Lengths of mesosternum and metasternum: 2.75 and 1.02. Lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II): fore leg: 3.08: 2.61: 0.31: 0.56; middle leg: 8.47: 7.60: 0.58: 0.80; hind leg: 8.85: 9.18: 0.65: 0.81. Fore trochanter without long setae on ventral side. Fore femur simple, moderately incrassate, length ca. 5.9 × maximum width (3.08: 0.52), moderately thickened at basal part and gradually tapering towards apex, flexor side without long, stiff setae. Fore tibia straight, with long, stout setae at apical third of extensor side. Fore tarsus covered with brown setae. Middle and hind femora slender and shorter than body length; middle and hind femora (in distal parts), middle and hind tibiae with scattered, short, brown spines. Claws stout, lengths of fore, mid- and hind claws: 0.18: 0.28: 0.27. Total length of abdominal sterna II-VII ca. 0.36 × body length (4.08: 11.25). Sternum VII 1.1 × length of two preceding sterna combined (1.34: 1.22), posteriorly narrowed, posterior margin straight. Connexival apex of sternum VII obtuse. Genitalia: not totally concealed by sternum VII; tergum VIII simple; gonocoxae concealed by sternum VII; proctiger acuminate, protruded, directed caudad.

Apterous morph: Unknown.

Remarks.

In the E. longipes species group, E. anderseni sp. nov. can be easily distinguished from E. longipes and E. terrestris based on the unique structure of the pygophore. In E. longipes and E. terrestris , posterolateral projections of the pygophore taper towards the pointed or narrow apex. In E. anderseni sp. nov., posterolateral projections are thickened at the distal part and bear dense, long, bristle-like setae. The female of the new species differs from E. longipes and E. terrestris by the shorter sternum VII (ca. 1.1 × the length of two preceding sterna combined, whereas sternum VII of the latter two species is ca. 1.5 × the length of two preceding sterna combined).

Eotrechus longipes can be distinguished from E. terrestris by the characteristics of fore trochanter, abdominal venter, and the posterolateral projections of the male pygophore. In E. longipes , the fore trochanter has a small tubercle bearing black, minute setae; the abdominal venter has a median groove from sterna V-VII; and the posterolateral projections of the pygophore are broad at the basal part and taper apically. In E. terrestris , the fore trochanter is without such a tubercle; the median groove is present only on sterna VI and VII; and the posterolateral projections of the pygophore are long and more slender.

Etymology.

This species is dedicated to the late Prof. Nils Møller Andersen (University of Copenhagen) for his influential contributions to the systematics and evolution of semi-aquatic bugs, including the genus Eotrechus .

Distribution.

India: Meghalaya (Fig. 26 ).

Eotrechus brevipes species group

Diagnosis. Both sexes: fore femur short and stout, strongly incrassate basally, gradually tapering towards apex, and without stiff setae on flexor side; fore tibia distinctly curved. - Male: posterior margin of metasternum simple, without a fringe of short, black setae; abdominal venter without median patch of long, soft setae; posterior margin of sternum VII only slightly emarginated; pygophore with a pair of posterolateral projections. Female: mediotergite VIII flap-like, posterolaterally with grooves; genitalia enclosed by sternum VII and mediotergite VIII.

Species included. E. brevipes Andersen, 1982.

Figures

Figure 20. Habitus of Eotrechus species. A. E. longipes, apterous male from Nepal; B. E. anderseni sp. nov., macropterous female.

Figure 22. Eotrechus anderseni sp. nov., holotype. A. Left fore leg; B. Abdomen, ventral view; C. Genital capsule, dorsal view; D. Pygophore, ventral view; E. Paramere (A, B. Same scale; C, D. 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.