Hydrometra borneensis, Zettel & Yang, 2004

Zettel, Herbert & Yang, Chang Man, 2004, New Oriental Species And Subspecies Of Hydrometra Latreille (Heteroptera: Hydrometridae), Raffles Bulletin of Zoology 52 (2), pp. 389-398 : 391-393

Hydrometra borneensis , new species

( Figs. 6-9 )

Hydrometra maidli Hungerford & Evans, 1934: Polhemus & Polhemus, 1995: 34-36 (part, misidentification); Yang, Lua & Chang, 1994 (misidentification).

Material examined. – Holotype - (macropterous male): EAST MALAYSIA: Sabah, Sandakan, Kg. Batu Putih, Sg. Kinabatangan, SAFODA, 7 Apr.1994, coll. H. K. Lua & C. Y. Chang (SBM).

Paratypes – 3 males, 2 females (macropterous, incl. allotype); 2 males, 2 females (brachypterous including “morphotypes”), same data as holotype (ZRC, NHMW); 4 males, 5 females (macropterous); 4 males, 2 females (brachypterous), Sandakan, Danau Biandung Besar, Sg. Kinabatangan, 11 Apr.1994, coll. H. K. Lua & C. Y. Chang (SBM, ZRC, NHMW); 5 males, 3 females (macropterous), Sandakan, stream near Danau Biandum Kechil, Sg. Kinabatangan, 9 Apr.1994, coll. H. K. Lua & C. Y. Chang (ZRC, SBM); 1 female (brachypterous), Tawau, Sg. Nasib Kita, ca. 66.5 km to Semporna, 41.5 km to Tawau, 6 Oct.1996, coll. H. H. Tan & Y. Y. Goh (ZRC); Sarawak: 1 male, 2 females (brachypterous), 1 female (macropterous), Sg. Engkurah, 8.5 km fr. Tebakang to Mongkos, 16 May.1994, coll. M. Kottelat (SKM, ZRC); 1 male (brachypterous), 1 female (apterous), Sg. Stuum Muda, nr. Lundu ferry point at Bg. Kayan, 2 Sep.1996 (ZRC); 1 male, 1 female (brachypterous), Baram basin, Bario plateau, Pa’ Umor, Dapur river 10 Jun.2002 (ZRC); 15 males, 10 females (brachypterous), Kelabit Highland, 1000 - 1200 m, Bareo – Arur Dalam, puddles on meadows, 26 Feb. – 1 Mar.1993, coll. H. Zettel, # 11 (NHMW); BRUNEI: 4 males, 14 females (brachypterous), 1 male (macropterous), Tutong Dist., Logon Uluh Boyoh and Bawang Ulop, pool, 17 May.1996, coll. H. H. Tan (ZRC); INDONESIA: Kalimantan: 1 male, 1 female (macropterous), Kalimantan Timur; Mahakam Basin; Danau Semayang, 8 Nov.1999 (MZB); 1 female (brachypterous), Mahakam Basin, 60 km from Samarinda, 2 Dec.1999 (ZRC); 1 female (brachypterous), Kalimantan Barat, Kabupaten Pontianak, Lubok Raundal, 26 Apr.1998 (ZRC).

10); second mesotarsomere of holotype 1.4 times as long as third; metafemur lined with long, erect hairs.

Abdomen elongate and relatively narrow; tergite 7 posteriorly 1.5 times as wide as anterior margin, with convex surface; connexival corner obtuse, without prominent pilosity. Sternite 7 posteroventrally slightly swollen, bearing 2 broad patches

Description of holotype, macropterous male. – Body length 11.1 mm (range 10.8 – 11.8 mm, n = 9), head length 3.2 mm, head width at eyes 0.45 mm, width at metacetabula 0.64 mm, length of antennomere 2: 1.3 mm, length of mesotibia 4.3 mm.

Colour: mainly yellowish brown, body usually light brown; connexiva brownish black; antennae yellowish brown, darker towards apex; legs yellow, more or less darker brown on tarsi and apices of femora and tibiae; sides of thorax or abdomen with more or less distinct whitish stripe; pronotum medially with distinct white stripe, continued onto posterior part of head, but less distinct; forewing brown with distinct white stripe.

Structural characteristics: head long, width at eyes slightly wider than at antennal tubercles (1.1 times), AO 2.7 times as long as PO; anteclypeus small, subtriangular, as long as wide, with convex sides, angular apex, whole surface smooth and shining ( Fig. 6 ); maxillary plate narrow, elongate, with straight ventral margin, hardly covering base of gular lobe laterally; minimum dorsal distance between eyes 0.7 times of eye width; rostrum in resting position slightly surpassing posterior margin of eye; relative lengths of antennomeres ca. 0.4: 1.0: 2.1: 1.0.

Pronotum 0.55 times head length; pronotum with few pits anteriorly weakly delimiting collar, some larger pits more or less arranged in longitudinal rows posteriorly; few pits on acetabula; wings reaching posterior half of tergite 5; distance between mes- and metacetabula 1.8 times that between pro- and mesacetabula; relative lengths of leg segments (relative to mesotibia = 100): profemur – 80, protibia – 92, protarsus – 2+9+5, mesofemur – 89, mesotibia – 100, mesotarsus – 1+8+5, metafemur – 107 metatibia – 137; metatarsus – 1+8+6; ratio of mesotarsus: mesotibia – 6.7 (range 6.2 – 6.7, n = of dense and long yellowish setae posteroventrolaterally; the patch of setae reaching sides in lateral view, and to the posterior margin of sternite 7, further dorsad close to connexivum margin; segment 8 relatively small, narrower than segment 7 posteriorly in dorsal view, and with rounded posterior corners, ventromedian carina, ventrolaterally with indistinct depressions, dorsomedially with distal process which is directed posterodorsad and distinctly shorter than dorsal outline of the tergite ( Figs. 8 , 9 ).

Description of allotype, macropterous female. – Similar to male, slightly longer, body length 12.8 mm (range 12.0 – 12.8 mm, n = 8), head length 3.6 mm, head width at eyes 0.50 mm, width at metacetabula 0.79 mm, length of antennomere 2: 1.3 mm, length of mesotibia 4.3 mm.

Structural characteristics: anterior part of head 2.6 times as long as posterior part; distance between mes- and metacetabula 1.8 times that between pro- and mesacetabula; wings reaching anterior half of tergite 5; relative lengths of leg segments (relative to mesotibia = 100): profemur – 82, protibia – 90, protarsus – 2+8+6, mesofemur – 94, mesotibia – 100, mesotarsus – 1+9+6, metafemur – 114, metatibia – 138, metatarsus – 2+9+6; ratio of mesotarsus: mesotibia 6.2 (range 6.0 – 6.6, n = 8); second mesotarsomere 1.6 times as long as third; metafemur without long hairs.

Abdomen elongate, weakly upcurved, with slightly convex sides in dorsal view; connexival margin without long setae; tergite 7 posteriorly 1.0 times as wide as anterior margin, whole surface convex; tergite 8 with distal caudal spine similar as in male, slightly shorter than dorsal outline of the tergite in lateral view; sternite 7 produced caudad, covering most of gonocoxae ventrally, with transverse, approximately half-ovate depression close to rounded, medianly weakly angulate hind margin ( Fig. 7 ).

Description of brachypterous male. – Body length 10.1 – 12.1 mm (n = 23, “morphotype” 10.9 mm); laterotergites with more or less distinct, continuous whitish stripe medially; pronotum 0.45 times head length; metanotum 0.35 times head length; distance between mes- and metacetabula 2.2 times that between pro- and mesacetabula; wing straps slightly surpassing or, rarely, only reaching base of tergite 2; ratio of mesotarsus: mesotibia 5.2 – 6.6 (n = 15; “morphotype” 5.6); abdomen 2.0 times as long as thorax along dorsal midline; fifth tergite 4.2 times as long as wide.

Description of brachypterous female. – Body length 11.4 – 12.6 mm (n = 15, “morphotype” 12.2 mm); most characteristics as in macropterous female or brachypterous male, respectively; pronotum 0.5 times head length; metanotum 0.35 times head length; distance between mes- and metacetabula 1.9 times that between pro- and mesacetabula; mesotarsus: mesotibia 5.1 – 6.4 (n = 12, “morphotype” 5.8); abdomen 2.1 times as long as thorax along dorsal midline; fifth tergite 3.7 times as long as wide.

Remarks. – Hydrometra borneensis , new species is closely related to H. maidli with which it was confused by Polhemus & Polhemus (1995). According to these authors, H. maidli is widely distributed from southern China to Sulawesi and Timor including one record from Kalimantan (Borneo). We have examined the types of H. maidli (from Sumatra) in the Natural History Museum Vienna and numerous additional specimens from West Malaysia, Singapore, Sumatra, and Java. The following characteristics have been proven to be consistent in all specimens examined: In both sexes of H. borneensis ( Figs. 7, 8 ) the process of tergite 8 is more curved dorsad than in H. maidli . The distinct difference is on sternite 7 of the male: The posterior patch of setae in H. borneensis is less dense, but broad (reaching sides in ventral view), and includes very long pilosity which reaches backward to posterior margin of sternite 7 and further dorsad nearly to the connexivum margin ( Figs. 8 , 9 ). In contrast, the patch of setae of H. maidli is shorter and more dense, but narrow (not reaching sides in ventral view), some dispersed longer setae may occur (especially in populations from Sumatra and Java), however, the setae never reach the hind margin of the segment ( Fig. 10 ). It seems that figures 54-55 in Polhemus & Polhemus (1995) do not belong to H. maidli , but is H. borneensis . In females of H. borneensis , the subapical depression of sternite 7 is relatively deep, of half-ovate shape ( Fig. 7 ), and with straight anterior margin. In H. maidli , this depression is less distinct but more circular, narrower, and in most specimens with convex anterior margin.

Ecological notes. – This species occurs in stagnant or slow flowing waters in both primary and secondary forests. A very common species in Kinabatangan Basin (Sabah), especially in flooded shores of pools, streams and puddles in forests.

Distribution. – Borneo ( Fig. 17).

Etymology. – Named for Borneo where it was found.

Figures

Figs. 6-8. Hydrometra borneensis, new species. 6, dorasal view of head, showing anteclypeus; 7, female terminal abdomen, lateral view; 8, male terminal abdomen, lateral view.

Figs. 9-16. 9, Hydrometra borneensis, new species, male terminal abdomen, ventral view. 10, Hydrometra maidli Hungerford and Evans, male showing patch of setae on sternite 7. 11-14. Hydrometra heoki heoki, new species. 11, head, dorsal view, showing anteclypeus; 12, male terminal abdomen, lateral view; 13, male terminal abdomen, vental view; 14, female terminal abdomen, lateral view. 15, Hydrometra heoki paya, new species, male terminal abdomen, ventral view. 16, Hydrometra gilloglyi Polhemus and Polhemus, male terminal abdomen, ventral view.