Eotrechus luaae, Duc, Tran Anh & Zettel, Herbert, 2006

Duc, Tran Anh & Zettel, Herbert, 2006, Notes on Eotrechus Kirkaldy, 1902 (Heteroptera: Gerridae), with descriptions of two new species, Zootaxa 1353, pp. 39-51 : 43-46

Eotrechus luaae sp.n.

( Figs. 9–16 )

Material examined. Holotype (apterous ɗ) and allotype (apterous Ψ), CHINA, Hainan Prov., Ledong, Jianfenglin forest reserve, cascade along road, leg. I­S. Chen et al., 13 Sep. 2005, THH05­87 ( ZRC).

Paratypes: CHINA, Hainan Prov.: 10ɗɗ 5ΨΨ (apterous), 1Ψ (macropterous), same label data as holotype ( BMNH, ZRC); 7ɗɗ 4ΨΨ (apterous), Qiongzhong, Baihua waterfall, near Qiongzhong town, leg. I­S. Chen et al., 11 Sep. 2005, THH05­73 ( NHMW, ZRC); 9ɗɗ 1Ψ (apterous), Qiongzhong, Linmushan forest park, ca. 15 km into track from road, leg. I­S. Chen et al., 11 Sep. 2005, THH05­77 ( ZRC).

Description of apterous form. Size: apterous males, length 7.50–8.00 (holotype 8.00), width 2.31–2.51 (holotype 2.51); apterous females, length 8.00–8.70 (allotype 8.40), width 2.48–2.81 (allotype 2.57).

Colour: Dorsal body mainly brown, covered with golden pubescence, with yellow markings on head, pronotum, 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, lateroposterior margin light brown (sometimes expanded). Pro­, meso­, metasternopleura, meso­ and meta­acetabula with dense reflective silvery pubescence. Metanotum, abdominal tergites mainly dark brown, tergites 5–7 usually with narrow yellowish­brown median stripe. All leg segments (including coxae) yellowish, except tarsi dark brown. Ventral body: prosternopleuron yellow; meso­ and metasternopleura usually dark brown or light brown; abdominal venter mainly light brown, sometimes darker.

Structural characteristics: Apterous male (holotype): Head width across eyes 1.72; interocular width 0.98; eye kidney­shaped on dorsal view, eye size 0.80. Antennae about 0.97x of body length (7.72: 8.00), lengths of segments 1–4: 2.21: 1.98: 1.45: 2.08; first segment with 4–5 black spines on apical part. Pronotum, broader than long, shorter than head length (1.09: 1.37); mesonotum length 1.80. Lengths of mesosternum and metasternum: 2.16 and 0.70. Lengths of leg segments (femur: tibia: tarsal segment 1: tarsal segment 2) as follows, fore leg: 2.87: 2.67: 0.29: 0.44; mid leg: 7.60: 6.60: 0.56: 0.59; hind leg: 7.90: 7.70: 0.54: 0.57. Fore femur ( Fig. 9 ) incrassate, length about 4.63x maximum width (2.87: 0.62), slightly constricted before apex, basal part with broad tubercle bearing patch of minute dark hairs; ventral surface of femur with 3–4 spinelike hairs (male paratypes: 0–4 hairs, or broken off); fore tibia slightly curved in apical part, with scattered long black spinelike hairs on external side of distal part and apex. Mid and hind femora slender and slightly shorter than body. Mid and hind trochanters without spines, mid and hind femora with black spines scattered on distal. Claws stout (fore claw very stout), lengths of fore, mid, hind claws 0.19: 0.21: 0.21. Abdomen relatively short, venter slightly depressed from segment 3–7, length of abdominal venter from sternum 2 to sternum 7: 1.82; sternum 7 about 1.48x length of two preceding sterna together (0.65: 0.44), posterior margin deeply emarginate, depth around 2/5 of sternum 7 length, margin with long, soft, brown hairs ( Fig. 10 ). Abdominal segment 8 long (dorsal length 0.81, ventral length 1.02), with medially produced posteroventral margin; abdominal spiracle of segment 8 produced into minute tubercle, near anterior margin ( Fig. 10 ). Genital segments relatively large, modified as follow: Proctiger ( Figs. 13–14 ): distinctly trilobed, posterolateral lobes covered with yellowish hairs, ventrocaudal surface of proctiger with dense patch of long, brushlike hairs (in “in situ” position not visible). Pygophore: on ventral view, long and slender and constricted on mid part, ventral surface convex, produced into median broad ridge, straight in lateral view, posterior part produced into narrow platelike structure, tapering towards apex ( Figs. 15–16 ). Paramere very short, blunt, with some soft hairs on apex.

Apterous female (allotype): Head width across eyes 1.76; interocular width 0.98; eye kidney­shaped on dorsal view, eye size 0.83. Antennae about 0.84x of body length (7.03: 8.40), lengths of segments 1–4: 1.96: 1.74: 1.32: 2.01; first segment with about 5–6 black spines on apical part. Pronotum broader than long, shorter than median head length (1.00: 1.37), mesonotum length 1.88. Lengths of mesosternum and metasternum: 2.12 and 0.76. Lengths of leg segments (femur: tibia: tarsal segment 1: tarsal segment 2) as follows, fore leg: 2.64: 2.28: 0.29: 0.44; mid leg: 6.80: 5.80: 0.57: 0.60; hind leg: 7.00: 6.65: 0.59: 0.59. Fore femur incrassate, length about 6.44x maximum width (2.64: 0.41), slightly tapering towards apex, base without tubercle; ventral with about 12 spinelike hairs in a row; fore tibia slightly curved apically, with many long black spinelike hairs along external side and on apex. Mid and hind femora slender and slightly shorter than body. Mid and hind trochanters without spines, mid and hind femora with black spines scattered distally. Claws stout, lengths of fore, mid, hind claws 0.18: 0.22: 0.22. Abdomen ( Fig. 11 ) moderate in length, length of abdominal venter from sternum 2 to sternum 7: 2.97; sternum 7 large, slightly tapering towards apex, length about 1.28x length of two preceding sterna combined (1.08: 0.84), posterior margin smooth. Genital segments not concealed by sternum 7, proctiger acute.

Description of macropterous female. Size: length 9.80, width 2.74, slightly larger than apterous form.

Colour: pronotum: a yellow median mark on anterior part, pronotal lobe totally dark brown or black, margin slightly less dark; wings dark brown or black, with golden pubescence denser on wing veins and anterior margin; colouration of head and other parts similar to that of apterous form.

Macropterous male: unknown.

Etymology. This species is named in honour of Ms. Lua Hui Kheng, curator of the Raffles Museum of Biodiversity Research ( Singapore), for her kind support of the authors’ work on Southeast Asian aquatic bugs.

Remarks. This new species is very closely related to E. pingae Andersen (from Guangdong Province, China) by the identical shape of male fore femur and the similar structures of abdomen and genital segments (median groove of ventral abdomen, emarginated posterior margin of sternum 7, plate­like structure on posterior part of pygophore, and trilobed proctiger). However, further details of the abdomen and the genital segments clearly prove that E. luaae is a separate species from E. pingae :

(1) Pregenital abdomen. In E. luaae , the median, longitudinal groove only from sterna 3–7, less conspicuous and broader than in E. pingae (there the groove running from sterna 2–7, narrow and deep); emargination of sternum 7’s posterior margin deeper in E. luaae than in E. pingae .

(2) Abdominal segment 8. Posterior margin produced into a small median and acute process (in E. pingae , only slightly produced).

(3) Pygophore. In E. luaae , ventral surface convex, produced into a median, broad ridge, straight in lateral view (in E. pingae , pygophore with a simple, flat ventral surface and round in lateral view); posterior plate narrower, slightly tapering towards apex (in E. pingae , broader than long and subrectangular); pygophore laterally without tubercle (in E. pingae , with a round tubercle on each side).

(4) Proctiger. In E. luaae posterolateral lobes more produced and with relatively short hairs (in E. pingae , posterolateral lobes not surpassing median lobe and with dense, relatively long, dark brushlike hairs); ventrocaudal surface of proctiger with dense patch of long, brushlike hairs (in E. pingae , patch not present, only some short and soft, yellowish hairs).

Eotrechus pingae is only known from a single male specimen, thus it is not possible to compare the females of these two species. The characteristics mentioned above also make E. luaae distinctly separable from other species of Eotrechus . This is the first time that the genus Eotrechus has been recorded from Hainan Island.

Figures

FIGURES 9 – 16. Eotrechus luaae sp. n. (9 – 10, 13 – 16: male; 11 – 12: female): (9) right fore leg; (10) abdominal venter; (11) abdomen, lateral view; (12) right fore wing; (13) proctiger, lateral view; (14) same, dorsal view; (15) pygophore, lateral view; (16) same, dorsal view.