Eotrechus fansipan, Polhemus & Tran & Polhemus, 2009

Polhemus, John T., Tran, A. D. & Polhemus, Dan A., 2009, The Genus Eotrechus (Heteroptera: Gerridae) In Vietnam With Descriptions Of Two New Species, Raffles Bulletin of Zoology 57 (1), pp. 29-37 : 32-33

Eotrechus fansipan , new species

( Figs. 1 , 4–10 , 17 )

Material examined. – Holotype (apterous male) and allotype (apterous female): VIETNAM, Lao Cai Prov., waterfall, 17 km northwest of Sa Pa , 1,935 m. [6,350 ft.], 22°21'17.0"N 103°46'28.3"W, water temp. 18.5°C., 8 Apr.2000, 1115–1300 hrs., CL 4401, coll. J. T. Polhemus, D.A. Polhemus & P. Nguyen ( USNM).

Paratypes: VIETNAM, Lao Cai Prov.: 32 apterous males, 35 apterous females, same locality data as holotype ( USNM, JTPC, BPBM, ZRC); 5 apterous males, 2 apterous females, 1 macropterous female, rocky streamlet with cascades, 16 km northwest of Sa Pa, 1,890 m. [6,200 ft.], 22°21'28.4"N 103°46'36.8"W, water temp. 17°C., 8 Apr.2000, 1330–1430 hrs., CL 4402, coll. J. T. Polhemus, D.A. Polhemus & P. Nguyen; 9 apterous males, 6 apterous females, 1 macropterous female, Bac Waterfall and smaller side waterfall, 15 km northwest of Sa Pa , 1,829 m. [6,000 ft.], 22°21'39.7"N 103°46'39.5"W, water temp. 19°C., 8 Apr.2000, 1500–1600 hrs., CL 4403, coll. J. T. Polhemus, D.A. Polhemus & P. Nguyen .

Description. – Size: apterous male, length 7.66–8.50 (holotype 8.50), width 2.48–2.74 (holotype 2.74); apterous female, length 8.55–9.49 (allotype 9.20), width 2.77–2.94 (allotype 2.87); macropterous female, length 9.54–9.60, width 2.61–2.77.

Colour. Apterous form: Dorsum mainly brown, covered with golden pubescence, with yellow markings on head, pronotum, and mesonotum as follows: head with yellow markings on anterolateral corners, next to inner margin of eyes, and a yellow marking on posterior margin; pronotum with yellow median longitudinal stripe, in lateral view with two yellow markings, one longer in upper part and one shorter on lower part; mesonotum mainly dark brown, with yellow median stripe running from anterior to posterior margin and tapering posteriorly, anterior part expanded laterally. Pro-, meso-, metasternopleura, meso- and metaacetabula with dense patches of reflective silvery pubescence. Metanotum, abdominal tergites mainly dark brown, tergites II–VII usually with narrow yellowish median stripe. All leg segments (including coxae) yellowish, except tarsi dark brown. Ventral body with prosternopleuron yellow; meso- and metasternopleura usually dark brown; abdominal venter mainly light brown.

Structural characteristics. Apterous male (holotype): Head width across eyes 1.80; interocular width 1.00; eye kidneyshaped in dorsal view, length 0.87. Antennae about 0.77× body length (6.55: 8.50), lengths of segments I–IV: 1.92: 1.56: 1.21:1.86; first segment with 5–6 black spines on apical part. Pronotum broader than long, shorter than head length (1.08: 1.49); mesonotum length 1.80. Lengths of mesosternum and metasternum: 2.28 and 0.71. Lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II) as follows, fore leg: 2.93: 2.71: 0.27: 0.52; middle leg: 7.30: 6.80: 0.67: 0.60; hind leg: 7.50: 7.70: 0.69: 0.67. Fore femur ( Fig. 4 ) incrassate, length about 4.65× maximum width (2.93: 0.63), slightly constricted before apex, basal part with broad tubercle bearing patch of minute dark hairs; ventral surface of femur with a row of about 10 spine-like hairs; fore tibia slightly curved in the middle, long spine-like hairs scattered on external side and denser at apical part ( Fig. 4 ). Mid- and hind femora slender and slightly shorter than body. Mid- and hind trochanters without spines, mid- and hind femora with scattered black spines. Lengths of fore, mid, and hind claws: 0.16: 0.25: 0.25. Abdomen relatively short, venter medially depressed from segment III to VI and more broadly depressed on segment VII, length of abdominal venter from sternum II to sternum VII: 1.96; sternum VII about 1.48× length of two preceding sterna together (0.71: 0.52), posterior margin deeply emarginate, around 2/5 of sternum VII length, margin with long, soft, brown hairs ( Fig. 8 ). Abdominal segment VIII long (dorsal length 0.87, ventral length 0.83), with posteroventral margin almost straight; abdominal spiracle of segment VIII not produced into minute tubercle. Genital segments relatively large, modified as follows: Proctiger trilobate ( Fig. 7 ), posterolateral lobes small, ventrocaudal surface of proctiger with dense patch of long, brushlike hairs ( Figs. 6, 7 ) (not visible in situ). Pygophore moderately long in ventral view and constricted on central section ( Fig. 8 ), two small tubercles near the narrowest part bearing long soft hairs (more visible in dorsal view) ( Fig. 10 ); ventral surface convex, round in lateral view ( Fig. 9 ); posterior part produced into short plate-like structure, with dense patch of long soft hairs on ventrolateral sides, apical margin almost straight ( Fig. 10 ). Paramere very short, blunt, with some soft hairs on apex.

Apterous female (allotype): Head width across eyes 1.78; interocular width 1.02; eye kidney-shaped in dorsal view, length 0.84. Antennae about 0.70× of body length (6.41: 9.20), lengths of segments 1-4: 1.82: 1.58: 1.19: 1.82; first segment with about 7 black spines on apical part. Pronotum broader than long, shorter than head length (1.03: 1.40), mesonotum length 2.03. Lengths of mesosternum and metasternum: 2.33 and 0.79. Lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II) as follows, fore leg: 2.94: 2.48: 0.37: 0.59; middle leg: 7.20: 6.60: 0.68: 0.67; hind leg: 7.20: 7.25: 0.70: 0.70. Fore femur slender, length about 6.68× maximum width (2.94: 0.44), slightly tapering towards apex, base without tubercle; ventral surface with about 12 spine-like hairs in a row; fore tibia almost straight, with many long black spine-like hairs along external side, particularly on distal part. Mid- and hind femora slender, slightly shorter than body. Mid- and hind trochanters without spines, mid- and hind femora with black spines scattered distally. Lengths of fore: mid: hind claws: 0.20: 0.24: 0.24. Abdomen ( Fig. 5 ) moderate in length, length of abdominal venter from sternum II to sternum VII: 3.38; sternum VII large, slightly tapering towards apex, length about 1.10× length of two preceding sterna combined (1.10: 1.00), posterior margin smooth. Genital segments not concealed by sternum VII; proctiger acute.

Remarks. – Eotrechus fansipan , new species, is closely related to E. pingae Andersen, 1998 ( E. pingae is known from a single male specimen only) and E. luaae Tran & Zettel, 2006 , especially in the structure of fore leg and genitalia. However, closer examination shows significant differences that separate the former from the other two (Table 1).

Etymology. – The name of this species is a noun in apposition and refers to Mt. Fansipan, the highest mountain in Vietnam, which is located near the type locality.

Ecological notes. – The type series of Eotrechus fansipan , new species, was taken on wet bedrock faces adjacent to a wide, unshaded waterfall along the road from Sa Pa to Lai Chau. The waterfall was set slightly back from the road on the upstream side, and the majority of specimens were taken on the wet rheocrenes to the right side of the fall when looking upstream ( Fig. 1 ). The surrounding vegetation consisted of disturbed montane subtropical forest, intermixed with dry bedrock exposures and grassy slopes. The stream below the falls dropped steeply downhill through a boulder-strewn channel and passed under the road bridge via a series of shaded pools, which harbored the unusual veliid Velia tonkina ; see Polhemus & Polhemus (2003) for further discussion of this interesting locality.

Figures

Figs. 1–3. Type locality for E. fansipan, new species, at a waterfall 17 km. northwest of Sa Pa, Vietnam. Both E. brevipes and E. fansipan, new species, occurred at this location. 1, general view of waterfall and surroundings, showing wet rheocrenes adjacent to the fall itself, on the left side of the photo, which provided habitat for E. fansipan, new species, and dry slopes to the right side of the photo, which provided habitat for E. brevipes. The senior author, standing to the right of the fall, provides scale; 2, lateral view of fall, showing dry bedrock faces in the foreground on which E. brevipes occurred; the photo was taken from near the position of the senior author in Fig. 1; 3, detail of E. brevipes habitat, showing clumps of vegetation scattered on open bedrock. Individuals of E. brevipes sheltered within the vegetation clumps.

Figs. 4–10. Eotrechus fansipan, new species, structural details: 4, male foreleg; 5, female abdomen, left lateral view; 6, male proctiger, left lateral view; 7, male proctiger, dorsal view; 8, male terminal abdomen, ventral view; 9, male pygophore, left lateral view; 10, male pygophore, dorsal view.

Fig. 17. Distributions of new species of Eotrechus in Vietnam: square = E. fansipan, new species; circle = E. pumat, new species.