Eotrechus pumat, 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 : 34-37

Eotrechus pumat , new species

( Figs. 11–17 )

Material examined. – Holotype (apterous male) and allotype (apterous female): VIETNAM, Nghe An Prov., Kem waterfall, Pu Mat Nature Reserve, 400 m [1,310 ft.], coll. J. T. Polhemus , 01 Apr.2000, CL 4385 ( USNM).

Paratypes: VIETNAM, Nghe An Prov.: 8 apterous males, 8 apterous females, same data as holotype ( USNM, JTPC, ZRC) .

Description. – Size: apterous male, length 5.72–6.10 (holotype 5.9), width 1.99–2.19 (holotype 2.13); apterous female, length 6.49–8.44, width 2.33–2.55.

Colour. Apterous form, body mainly brown (ventral side usually paler) with yellowish brown markings dorsally; dorsal surface covered with silvery or greenish pubescence. Head with one narrow median yellow stripe, anterolateral corners and posterior margin yellow. Antennae yellow to brown. Pronotum with five longitudinal yellow stripes on dorsal and lateral sides. Mesonotum mainly brownish yellow with six longitudinal markings: two slender dark brown lateral stripes, two slender dark brown sub-lateral stripes and two brown markings in the centre. Metanotum and abdominal tergum mainly dark brown. Pro-, meso- and metasternopleura with dense silvery and reflective patches of pubescence. Legs with all coxae, trochanters and femora yellow (slightly darker in females), all tibiae and tarsi brown.

Structural characteristics. Apterous male (holotype): Head width across eyes 1.36; interocular width 0.83; eye kidneyshaped in dorsal view, length of eye 0.65. Antennae about 1.03× body length (6.06: 5.90), lengths of segments I–IV: 1.88: 1.49: 1.17: 1.52; first segment with 6 black spinelike hairs in apical part. Pronotum broader than long, slightly shorter than head length (0.79: 1.19). Lengths of mesosternum and metasternum: 1.92 and 0.43. Posterior margin of metasternum with a median fringe of short black hairs ( Fig. 14 ). Lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II) as follows: fore leg: 2.33: 1.88: 0.22: 0.37; middle leg: 6.35: 4.75: 0.67: 0.57; hind leg: 6.60: 5.30: 0.79: 0.59. Fore femur ( Fig. 11 ) slightly concave at the middle part of ventral side and constricted at apical part, length about 6.13× maximum width (2.33: 0.38), ventral surface with three black stout hairs on basal half (two hairs in other paratypes); fore tibia straight, with few long black spine-like hairs on apical margin, fore tarsus covered with long, soft yellowish hairs. Middle and hind femur slender and slightly longer than the body, with scattered small brown spines (more on middle femur). Claws stout, lengths of fore, mid- and hind claws: 0.19: 0.22: 0.22. Abdomen ( Fig. 14 ) short, length of abdominal venter from sternum II to sternum VII = 1.11, with patch of long yellow hairs on median sterna II–VI. Sternum VII about 2.13× length of two preceding sterna combined (0.51: 0.24), posterior margin with very deep rectangular median notch (about half the length of sternum VII) ( Fig. 14 ). Genital segments large, pygophore with a pair of broad and thick posterolateral processes, as in Figs. 14–16 , these processes directed upward in lateral view ( Fig. 15 ); on each side of the process (dorsal and ventral) with a prominent tubercle (visible in lateral and dorsal view, Figs. 15, 16 ); in dorsal and ventral view, each process with a small finger-like process directed inwards ( Fig. 14, 16 ). Proctiger simple, elongate, unmodified ( Fig. 13 ). Parameres small and blunt.

Apterous female (allotype): slightly bigger than the male. Head width across eyes 1.40; interocular width 0.84; eye kidney-shaped, length 0.63. Antennae about 0.8× of body length (5.41: 6.80), lengths of segments I–IV: 1.55: 1.29: 1.06: 1.51; first segment with 2–3 black spines sub-apically. Pronotum slightly shorter than head length (0.79: 1.11). Lengths of mesosternum and metasternum: 2.21 and 0.56. Lengths of leg segments (femur: tibia: tarsal segment I: tarsal segment II): fore leg: 2.16: 1.86: 0.27: 0.40; middle leg: 6.70: 4.80: 0.75: 0.63; hind leg: 6.90: 5.30: 0.90: 0.62. Fore femur simple and slender, length about 6.8× maximum width (2.16: 0.32), ventral surface with 3 to 5 black spinelike hairs; fore tibia straight with some long black spines on apical margin, fore tarsus covered with long, soft yellowish hairs. Middle and hind femur slender and subequal to body length, scattered with small brown spines (more on middle femur). Claws stout, lengths of fore, mid- and hind claws: 0.19: 0.24: 0.24. Length of abdominal venter from sternum II to sternum VII about 0.29× body length (1.98: 6.80). Venter of sterna II–VII without patch of long hairs. Sternum VII about 1.63× length of two preceding sterna together (0.83: 0.51), posterior margin straight. Genital segments not concealed, proctiger round and slightly deflected ( Fig. 12 ).

Remarks. – Eotrechus pumat is closely related to E. vietnamensis Tran & Yang, 2006 . They share similar characteristics, including the dorsal colour pattern, the structure of the male fore femur ( Fig. 11 ), and modifications of the male and female pregenital abdomen ( Figs. 12, 14 ). Females of these two species are indistinguishable. These similarities suggest that they may be sister species. However, E. pumat can be easily separated from the latter by the unique structures of male genitalia ( Figs. 14–16 ).

Etymology. – The name of this species is a noun in apposition and refers to the type locality, the Pu Mat Nature Reserve in north-central Vietnam.

Ecological notes. – The type series was collected from Kem waterfall (Thac Kem) at the end of a trail in the Pu Mat Nature Reserve ( Fig. 17 ). This waterfall flows down over a rather irregular rock face into a large plunge pool below; an excellent color photo of this waterfall is provided in Sites & Vitheepradit (2007, pg. 18). The Eotrechus specimens moved rapidly over the slippery face of the waterfall, and were quite difficult to capture.

Figures

Figs. 11–16. Eotrechus pumat, new species, structural details: 11, male foreleg; 12, female abdomen, left lateral view; 13, male proctiger, dorsal view; 14, male terminal abdomen, ventral view; 15, male pygophore, left lateral view; 16, male pygophore, dorsal view.

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