Strongylovelia narusei, Zettel & Tran, 2009

Zettel, Herbert & Tran, A. D., 2009, First Inventory Of The Water Bugs (Heteroptera: Nepomorpha: Gerromorpha) Of Langkawi Island, Kedah, Malaysia, Raffles Bulletin of Zoology 57 (2), pp. 279-295 : 285-287

Strongylovelia narusei , new species

( Figs. 3 , 13–16 )

Material examined. – Holotype (apterous female) and paratypes (4 apterous females, 3 apterous males, 1 macropterous-dealate male), HZL10 , labeled “ MALAYSIA, Kedah \ C-Langkawi, Air Tejun,\ nr Kampung Buku , small\ stream, 22.11.2006 \ leg. H. Zettel ( HZL10 )”, holotypes and paratypes in NHMW, 1 paratype female and 1 paratype male in ZRC. – Further paratypes from Malaysia: 1 apterous female, 1 apterous male “MAL, Terengganu, Sekaya,\ Sg. Brang. HK Lua,\ 21-OCT-1998,\ LHK040” ( ZRC).

Description of apterous female. – Measurements: Body length 1.31–1.42 mm (holotype 1.42 mm). Body width 0.74–0.80 mm (holotype 0.79 mm). Relative lengths of antennomeres 1–4 (holotype): 0.9: 1.0: 1.8: 1.4. Relative lengths of leg segments (relative to mesofemur length = 100; holotype): profemur 45, protibia 44, protarsus 4+14, mesofemur 100, mesotibia 81, mesotarsus 36+23, metafemur 71, metatibia 56, metatarsus 9+14.

Body tear-shaped, sides of abdomen not strongly convergent ( Fig. 3 ). Dorsal aspect black except some indistinct dark orange marks along dorsal eye margin and mesonotum yellowish white except narrow lateral margins. In lateral aspect pro-, meso-, and metapleura yellowish white except narrow or broad stripe along dorsal margin of meso- and metapleura black, mesacetabula with or without dark mark, and metacetabula with narrow or broad dark stripe distally. Ventral aspect black, except prosternum and mesosternum yellowish white with or without infuscated acetabula. Antenna and legs black, except metatrochanter, profemur except apex, and basal half of metafemur whitish; coxae variably infuscated.

Median pronotal length 0.35 times eye length. Dorsum of thorax with very short, decumbent pilosity. In lateral aspect, head and mesonotum with scattered black erect setae, those on mesonotum much shorter than those on head. Posterior corners of meso-metanotum slightly acute, apex without conspicuous long setae. Structures of abdomen ( Figs. 3 , 13, 14 ) relatively simple: in dorsal view ( Fig. 13 ), connexiva nearly evenly converging, slightly more on segments 5 and 6. Laterotergites directed more or less dorsad, slightly laterodorsad anteriorly and weakly mediodorsad posteriorly, so that all tergites completely, and all sternites partly visible in dorsal view. Each sternite laterally with 1–2 long, black setae beneath dorsal margin; sternite 7 additionally with relatively long pilosity at connexival corners. Laterotergites 2–4 and 7 and tergites 1–7 with short pilosity; laterotergites 5-6 with conspicuous, mesad directed setae; tergite 7 with some long black setae on its lateral portions. Suture between tergites 1, 2, and 3 weakly impressed, medially hardly curved cephalad; all other sutures well developed and nearly straight. Tergites without median elevations, and dull. Hind margin of tergite 7 slightly convex; tergite 8 medially with shallow impression, with hind margin bearing few long, black setae. In lateral view ( Fig. 14 ), few long setae surpassing connexival margin; connexival corners acute, with black pilosity. Gonocoxa plate-like; proctiger small, directed ventrocaudad.

Description of apterous male. – Measurements: Body length 1.06–1.11 mm. Body width 0.62–0.66 mm.

Colour similar to that of female, except yellowish marks on meso- and metanotum separated by narrow black line and pronotum medially with small orange mark in one specimen. Dorsum of thorax and abdomen shinier than in female. Median pronotal length 0.4 times eye length. Black setae laterally on mesothorax and sternites similar with those of female, longest setae on sternites ca. 0.10 mm long. Dorsum of body with very short pubescence, but head and tergite 7 with some longer setae in addition. Suture between tergites 1 and 2 weak, other sutures between tergites well developed. Tergite 5 circa 8 times as wide as long at midline. Paramere ( Fig. 15, 16 ) moderately curved at basal third, strongly twisted, relatively broad, subapically weakly widened (in caudal view), apex very acute.

Description of macropterous male. – Body length 1.18 mm, body width 0.67 mm. Colour similar as in apterous morph, but posterior half of pronotum with half-ovate yellowish mark, and metafemora yellowish white in proximal three-fifths. Pronotum very large, at midline about 2.0 times as long as eye, covering meso- and metanotum, with distinct humeri. Wings of dealate specimen broken off at base, approximately at level of posterior apex of pronotum. All tergites almost flat, tergite 1 not longer than tergite 2.

Macropterous female: unknown.

Etymology. – This species is dedicated to Tohru Naruse, who accompanied the authors for field work in Langkawi.

Remarks. – This species belongs to the S. esakii group as defined by Lansbury & Zettel (1997). Within this group, two species complexes are recognized. The S. esakii complex includes S. esakii Lansbury & Zettel, 1997 from Borneo, S. palawanensis Lansbury & Zettel, 1997 from Palawan ( Philippines), and some other undescribed Bornean species. It can be distinguished by wide tergites of the apterous female that are completely visible in dorsal view as the laterotergites are directed laterad or laterodorsad, by tufts of hairs on sternite 2 of the female, and by a slender distal section of the parameres of the males (see Lansbury & Zettel, 1997). The second complex, the S. aberrans complex, contains S. aberrans Lansbury & Zettel, 1997 from Borneo, S. setosa Zettel & Tran, 2005 from Vietnam, S. narusei , and several other undescribed species from Borneo and southeast Asia. Species of this complex can be recognized by the laterotergites of the apterous female which are flapped over the tergites to a varying degree (at least slightly on segments 6 or 7), by a row of long setae on the sternites of the female (situated parallel with and beneath the connexival margin), by the absence of hair tufts on the female’s sternite 2, and by the subapically slightly widened paramere of the male (male of S. aberrans unknown). Additionally, the species have a similar colour pattern (but some variation in the extent of the yellow base of the metafemur) and agree in the general structures of meso-metanotum and abdomen. For comparison, the authors used the type series of S. setosa and the holotype (female) of S. aberrans . Beside the specimens from Langkawi, only two specimens from Terengganu match the diagnostic characters of S. narusei and were included in the type series. Numerous specimens were studied from other parts of peninsular Malaysia (Johore), from Singapore, from the Indonesian islands of Batam and Bintan, and from Sarawak on Borneo (all in ZRC), but it was concluded that they either belong to additional undescribed species or that at least the differences are too big to include them in the type series of S. narusei without a more detailed revision of the whole complex. Strongylovelia narusei differs from S. aberrans and S. setosa (and from most other material studied, except one population from Johore which is eventually conspecific with S. narusei ) in a rather conspicuous long pilosity on laterotergites 5 and 6 of the apterous female, and from S. setosa in the more slender apex of the paramere of the male. The ratio of antennomeres 2 and 3 of females is 1.9–2.0 in S. aberrans , 1.7–1.8 in S. setosa and S. narusei . The posterior corners of the meso-metanotum of apterous females bear a dense group of long black setae in S. narusei , which is absent or inconspicuous in other species. An important characteristic to separate species of the S. aberrans complex might be the presence or absence of long setae on tergite 7 of apterous females, which either occur in small numbers on its lateral areas or in a more or less transverse row close to the tergite’s hind margin. Unfortunately, these setae tend to break off, so that in some cases either only their base is visible or they cannot be seen at all. Such setae could be observed on the lateral parts of tergite 7 of S. narusei and S. aberrans , but not in S. setosa . The apterous female of S. setosa differs also from both species in a deeper, more elongate depression of the tergite 8.

Distribution. – Malaysia: Langkawi, Terengganu.

Figures

Figs. 2–6. Habitus of (2) Hydrotrephes langkawicus, new species (macropterous male, paratype). (3) Strongylovelia narusei, new species (apterous female, paratype). (4) Microvelia (Picaultia) minutissima, new species (apterous female, paratype). (5) Microvelia (Picaultia) minutissima, new species (macropterous male, holotype, right forewing broken off). (6) Frontal view of cephalonotum of Hydrotrephes langkawicus, new species (macropterous male, paratype).

Figs. 13–16. Strongylovelia narusei, new species. (13) Abdomen of apterous female (with corners of meso-metanotum), dorsal view. (14) Abdomen of apterous female, lateral view. (15) Paramere of male, lateral view. (16) Paramere of male, perpendicular view on apical part.