Amemboa riparia Polhemus & Andersen, 1984

Polhemus, J. T. & Tran, A. D., 2012, Taxonomic notes on Amemboa lyra Paiva and Amemboa riparia Polhemus & Andersen (Hemiptera: Heteroptera: Gerridae), Zootaxa 3341, pp. 54-58 : 55-57

Amemboa riparia Polhemus & Andersen, 1984 , stat. nov.

(Figs. 3,4)

Amemboa riparia Polhemus & Andersen, 1984: 90–92 , Figs. 66, 76–78 (type locality: Fang , Thailand).

Material examined. HOLOTYPE: apterous male, “ Thailand, 7km NW of Fang, Horticultural Experimental Station , 30.x.–2.xi. 1979, Zool. Mus. Copenhagen Exped.” ( ZMUC) . PARATYPES: 1 male (macropterous), same label as holotype ( ZMUC) ; 1 male (apterous), “ Thailand, 18°46’N 98°48’E, Chiang Mai, waterfall, 29.xi.1978, M. Holmen leg.” ( ZMUC) .

Others — LAOS: 1 male (apterous), 1 male, 1 female (macropterous), Laos centr., Khammouan Prov., Ban Khoun Ngeun env., N18º07’, E104º29’, alt. 250m, coll. E. Jendek & P. Patcholatko, 4–16, 25–30 Nov. 2000 ( NHMW) .

VIETNAM: Dien Bien Prov.: 3 males, 1 female (apterous), Na Tau, Nam Rom river , coll. Tran A.D., 25 Jul. 2004, DY0412 ( ZRC) ; 1 female (apterous), Nam Rom river , 10km to Dien Bien Phu City, coll. Tran A.D., 25 Jul. 2004, DY0413 ( ZRC) ; 4 females (apterous), Muong Phang, Muong Phang stream, coll. Tran A.D., 26 Jul. 2004, DY0415 ( ZRC) ; 1 male, 2 females (apterous), Dien Bien Dong, Keo Lom, Huoi stream, coll. Tran A.D., 27 Jul. 2004, DY0417 ( ZMHU) ; 2 males (apterous), no name stream northeastern side, near DBP City, coll. Tran A.D., 29 Jul. 2004, DY0420 ( ZRC) . Nghe An Prov.: 2 males, 4 females (apterous), Choang River, nr. edge of Pu Mat Nature Reserve , 165 m . [540 ft.], water temp. 25.5°C, coll. J. T . Polhemus and P. Nguyen, 2 Apr. 2000, CL 4387 ( JTPC) ; 1 male, 1 female (apterous), Bac stream, nr. Pu Mat Nature Reserve , 200 m ., water temp. 24°C, coll. J. T. Polhemus and P. Nguyen, 2 Apr. 2000, CL 4388 ( JTPC) . Lai Châu Prov.: 38 males, 48 females (apterous) , 2 males (macropterous), small tributary streams to Lai River at Lai Châu , 230 m ., 22°02'35"N, 103°10'03", water temp. 23°C, coll. J. T . Polhemus and P. Nguyen, 10 Apr. 2000, 16:00–18:00 hrs., CL 4408 ( JTPC) .

THAILAND: Chiang Mai Prov.: 1 male, 2 females (apterous), Chiang Mai, pool, near road side, coll. C.M. Yang & T . B. Lim , 7 Sep. 1998, YCM203 B ( ZRC); 1 male (apterous), NW Chiang Mai, Soppong, side stream off Pai river , coll. C.M. Yang & T . B. Lim , 9 Sep. 1998, YCM214 ( ZRC) ; 4 males, 1 female (apterous), NW Chiang Mai, Soppong, side stream to Pai river , coll. C.M. Yang & T . B. Lim , 9 Sep. 1998, YCM212 A ( ZRC); 2 males, 3 females (apterous) , 1 male (macropterous), NW Chiang Mai, Soppong, nr. Lod Cave , puddles, plantation, coll. C.M. Yang & T . B. Lim , 9 Sep. 1998, YCM212 B ( ZRC); 2 males, 3 females (apterous) , 1 female (macropterous), NW Chiang Mai, Soppong, Pai River , coll. C.M. Yang & T . B. Lim , 9 Sep. 1998, YCM211 ( ZRC) ; 1 male (apterous), NW Chiang Mai, Pai river , nr. Pai, 7 Sep. 1998, YCM204 ( ZRC) ; 1 male, 2 females (apterous), Chiang Mai to Pai , waterfall fr. wet boulders, coll. C.M. Yang & T . B. Lim , 7 Sep. 1998, YCM201 A ( ZRC). Phrae Prov.: 4 males, 1 female (apterous) , 1 male (macropterous), 50km NE Phrae, 5km SE Huai Kaet , coll. H. Zettel (18a), 18 Nov. 1995 ( NHMW) ; 2 males, 1 female (macropterous), 50km NE Phrae Huai Kaet, Kaet river , coll. H. Zettel (17b), 17–18 Nov. 1995 ( NHMW) ; 3 males, 2 females (apterous), 8 males (macropterous), 50km NE Phrae, Huai Kaet , coll. H. Zettel (17a), 17 Nov. 1995 ( NHMW) . Phetchabun Prov.: 1 male (apterous), Huai Nam Phang, S Ban Nam Nao, coll. H. Zettel (25), 25 Nov. 1995 ( NHMW) ; 8 females (apterous), Nam Nao NP, Huai Phrom Laeng, coll. H. Zettel (22), 24 Nov. 1995 ( NHMW) . Songkhla Prov.: 1 male (apterous), Nam Tok Khao Chong , coll. H.K. Lua, 26 Oct. 1998, LHK0410 ( ZRC) .

MALAYSIA: Perak: 1 male (apterous), Sg. Lebey, along Gerik-Kota Bahru Rd. , coll. H.K. Lua, 17 Feb. 1997, LHK0325 ( ZRC) . Selangor: 1 male, 4 females (apterous), Ulu Gombak , temp. puddles along logging trial, coll. C.M. Yang & T . B. Lim , 16 Nov. 1995, YCM88 ( ZRC) . Johor: 1 male (apterous), stream at the palm estate near Gunong Pulai , coll. H.K. Lua, 15 Aug. 1995, LHK285 ( ZRC) ; 1 male (apterous), Gunong Panti , coll. C.M. Yang, 20 May1993, #Y833 ( ZRC) .

SINGAPORE: 2 males, 6 females (apterous), Rail way at Clementi Rd, coll. D. Murphy, 10 Feb. 1986 ( ZRC) ; 2 males, 6 females (apterous), Nee Soon , forest stream, coll. D. Murphy, 3 Jan. 1986 ( ZRC) ; 1 male (apterous), MacRitchie Reservoir , Stream Jc-II, coll. H.K. Lua et al., 2 Jun. 1994, NS148J ( ZRC) ; 2 males (apterous), Bukit Timah Nature Reserve , Stream E, coll. H.K. Lua et al., 13 Dec. 1995, NS212B ( ZRC) ; 1 male, 1 female (apterous), Chestnut Seletar stream, coll. H.K. Lua et al., 30 May1994, NS145 ( ZRC) ; 1 male, 2 females (apterous), Chestnut Drive stream, coll. H.K. Lua et al., 30 Dec. 1994, NS170 ( ZRC) ; 1 male, 1 female (apterous), ZRC .6.18171; 3 males, 2 females (apterous), BTNR , coll. H.K. Lua et al., 13 Dec. 1995, NS212C, ZRC .6.18520; 2 males, 1 female (apterous), Bukit Timah Nature Reserve , coll. H.K. Lua et al., 4 Dec. 1995, NS201B, ZRC .6.18404; 5 males, 7 females (apterous), Bukit Timah Nature Reserve , coll. T . Wong & S.H. Leong, 13 Dec. 1995, NS212B ( ZRC) ; 6 males, 8 females (apterous), Bukit Timah Nature Reserve , coll. H.K. Lua et al., 4 Dec. 1995, NS202, ZRC .6.18427; 14 males, 11 females (apterous), Bukit Timah Nature Reserve , coll. H.K. Lua et al., 4 Dec. 1005, NS201B, ZRC .6.18410; 24 males, 11 females (apterous), Bukit Timah Nature Reserve , coll. H.K. Lua et al., 6 Dec. 1995, NS205, ZRC .6.18455; 2 males, 3 females (apterous), Bukit Timah Nature Reserve , coll. H.K. Lua, T . B. Lim & S.H. Leong, 8 Dec. 1995, ZRC .6.18417; 3 males (apterous), Chestnut Dr., Gangsa stream, coll. C.M. Yang et al., 23 Jun. 1994, NS166, ZRC .6.18286; 1 male, 2 females (apterous), Bukit Timah Nature Reserve , coll. T . Wong & S.H. Leong, 13 Dec. 1995, NS212A, ZRC .6.18549; 1 male, 1 female (apterous), MacRitchie , Sime Rd, “Hc” stream, coll. H.K. Lua et al., 13 Jul. 1995, NS197, ZRC .6.18575; 2 males (apterous), Bukit Timah , Malayan railway, coll. C.M. Yang & S.H. Goh, 1 Jul. 1996, YCM160 ( ZRC) ; 1 male (apterous), Sime Rd. , coll. C.M. Yang et al., 24 Mar. 1994, #Y864 ( ZRC) .

Diagnosis. Size: males: length 3.7–4.0, width 1.29–1.38 (apterous), length 4.7–5.0, width 1.35–1.38 (macropterous); females: length 3.8–4.5, width 1.38–1.54 (apterous), length 5.2–5.3, width 1.48–1.52 (macropterous). Antennal segment 1 with about 6 spines along its length and 3 or 4 spines near apex. Mesosternum about 9.0 times as long as metasternum. Male’s fore leg: femur with an elongate patch of black hairs at basal ½ and 1 tuft of short hairs proximally; tibia slightly curved and thickened in the middle, inner side with a long patch of brown hairs ( Fig. 3). Male genitalia: hind margin pygophore distinctly trifid with a median lobe and 2 wellproduced postero-lateral lobes ( Fig. 4); lateral arms of proctiger shorter and broader (than those of A. lyra ). Female: sternum 7 slightly longer than all preceding sterna combined; hind margin of tergum 8 distinctly emarginated, postero-lateral corners with some long yellowish hairs.

Remarks. According to Polhemus & Andersen (1984), Amemboa riparia Polhemus & Andersen, 1984 , and A. lyra ( Paiva, 1918) can be separated from each other mostly by the structure of the male fore femur. In addition, based on the figures by these authors (see Polhemus & Andersen, 1984: Figs. 73–75), A. riparia also differs from the latter species by the modifications of the pygophore: both species possess a trifid apical part of pygophore, but the median and lateral lobes are more produced in A. riparia . Zettel & Chen (1996) synonymized A. riparia with A. lyra based on some samples from Thailand that showed the variation of fore femur (presence/ absence of middle hair tuft on fore femur); but the genital structures were similar. However, Zettel & Chen (1996) did not have access to the type material of A. lyra (in the Zoological Survey of India).

We also observed slight variation in the fore femur of three males from different samples of A. riparia (from northern Thailand: locality (17a): one macropterous; locality (17b): one macropterous; and from northern Vietnam: DY0420: one apterous); these specimens have a small tuft of hairs in the middle of the fore femur, but they are very inconspicuous. In two of these three specimens, the middle tuft of hairs only appears on either the left or right femur, the hairs of this tuft are short, and this tuft is never as thick as in the typical form of A. lyra . In all male specimens with fore femoral variation, the pygophore structures match those of the A. riparia form. Such intraspecific variation of the fore femur has never been observed in other species of Amemboa . These abnormalities clearly occur at a very low rate within the large series of specimens included here. Thus, in our opinion, the fore femoral structure is still a good and reliable character for species identification (with the very few exceptions stated above), when it is used in combination with the characters of the male genitalia.

All specimens of the Amemboa riparia form (with only two patches of hairs on fore femur) examined in this study do not show any variation in genital structure and match the illustration of A. riparia by Polhemus & Andersen (1984). In addition, no specimen fits the illustration of A. lyra by Polhemus & Andersen (1984). Slight variations in the shape of the pygophore were observed in the A. riparia form: the elevation of median lobe can be more or less in different samples; however, the lateral lobes were observed to be stable, more produced compared to the form in A. lyra .

The specimens of A. lyra that we examined in this study were collected from Mandalay Division and Shan Division, Myanmar. According to the Times Atlas of the World (1992), plate 25, these localities (Maymyo in Mandalay Division, and Shwelinban village near Inle Lake in Shan Division) are near Taung-gya (type locality of A. lyra ). These specimens clearly fit the description of Onychotrechus lyra by Paiva (1918) and A. lyra by Polhemus & Andersen (1984). The A. lyra specimens from the localities above can thus be considered as “topotypes”. Further comparison shows that male specimens of A. lyra (from Mandalay and Shan Divisions) is distinctly different from those of A. riparia from other localities ( Thailand, Laos, Vietnam, Malaysia, and Singapore) in the structure of the male’s fore leg and the shape of the pygophore, as well as in the shape of the lateral arms of the proctiger.

From all the accounts discussed above, Amemboa riparia Polhemus & Andersen, 1984 , is herein recognised as a valid species. Nevertheless, A. lyra and A. riparia are closely related to each other.

Distribution. Laos, Vietnam, Thailand, Peninsular Malaysia, and Singapore.