Microvelia (Picaultia) minutissima, 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 : 288-289

Microvelia (Picaultia) minutissima , new species

( Figs. 3, 4 , 17-23 )

Material examined. – Holotype (macropterous male) and paratypes (2 apterous females, 1 macropterous male, 5 macropterous females), HZL1 b, labeled “ MALAYSIA, Kedah \ W-Langkawi, Telaga Tujuh \ stream, 20.11.2006 \ leg. H. Zettel ( HZL1 b)”, holotype and paratypes in NHMW, 1 paratype macropterous female in ZRC. – Further paratypes from Malaysia: 1 male (macropterous), 1 female (macropterous) “MAL- Selangor, Ulu\ Gombak;\ 06-MAY-1996 \ HK Lua et al.\ LHK0305” ( ZRCS). – Further paratypes from Singapore: 7 males, 5 females (apterous) “SIN- Bt. Timah NR \ HK Lua et al.\ 08-DEC-1995 \ NS0209” ( ZRCS, NHMW); 2 females (apterous) “ ZRC Chestnut Drive\ NS 128A\ 5 th May 1994 ” ( ZRCS); 3 males (apterous) “SIN- Chestnut Dr.,\ Seletar Reservoir,\ 26-MAY-1994 \ HK Lua et al.\ NS0142C” ( ZRCS, NHMW); 3 females (apterous) “SIN, Chestnut Dr.,\ Seletar Reservoir,\ “Ua2” side stream; HK Lua et al.\ 26-V-1994, NS142G” ( ZRCS); 2 females (apterous) “Nature Reserves Survey\ Chestnut Dr., NS 142C\ 26 May 1994 ” ( ZRCS); 1 male (apterous), 1 female (apterous) “Nature Reserves Survey\ Chestnut Dr., NS 138B\ Singapore\ 19 May 1994 ” ( ZRCS); 1 male, 1 female (apterous) “stm #H, Mac Ritchie\ Forest, 2.2.1994 \\ NS124F” ( ZRCS); 1 female (apterous) “Nature Reserves Survey\ MacRitchie, NS 161D\ Singapore \ 13 June 1994 ” ( ZRCS); 2 females (apterous) “Nature Reserves Survey\ MacRitchie, NS 161B\ Singapore, 17 June 1994 ” ( ZRCS); 1 male (apterous), 1 female (apterous) “Nature Reserves Survey\ Nee Soon Swamp Forest \ NS 158B, Singapore \ 13 June 1994 ” ( ZRCS); 1 female (apterous) “SIN- Nee Soon\ swamp forest;\ 12-JUN-1995 \ HK Lua et al.\ NS0187A” ( ZRCS); 1 female (apterous) “SIN- Nee Soon\ KL Yeo\ 06-MAY-1992 \ YKL0794A” ( ZRCS); 1 male, 2 females (apterous) “ ZRC Nee Soon Swamp Forest \ NS126A upstream #23\ 28 April 1994 ” ( ZRCS).

Description of macropterous male. – Body length 1.28– 1.32 mm (holotype: 1.31). Pronotal width 0.56–0.58 mm (holotype: 0.58). Length of second antennomere of holotype 0.11 mm. Length of metatibia of holotype 0.42 mm.

Colour ( Fig. 3 ): Head and pronotum brownish, humeri, anterior and posterior margin of pronotum yellowish orange to different extend. Sides and venter mainly dark brown, connexival margins, segments 7 and 8, and genitalia yellow or light orange. Antennae brown, except base yellow. Legs yellow, but apices of femora and tibiae, and all tarsi brownish. Fore wings pale brown, base and two weakly delimited spots whitish.

Pilosity: Generally short, except lateral hind margin of sternite 7 set with long setae.

Dorsum without large black impressions. Head width ca. 1.2 times head length. Relative lengths of antennomeres 1–4 (holotype): 1.0: 1.0: 1.2: 2.5. Relative lengths of leg segments (relative to metatibia length = 100; holotype): profemur 66, protibia 54, protarsus 32, mesofemur 74, mesotibia 66, mesotarsus 11+28, metafemur 85, metatibia 100, metatarsus 12+30. Profemur slender. Protibia straight, distally widened, apically with long slender process set in blunt angle with tibia axis and bearing apically a minute grasping comb ( Fig. 17 ). Mesotibia with short process bearing minute grasping comb ( Fig. 18 ). Abdomen slender ( Fig. 20 ). Sternite 6 without modifications. Sternite 7 anteromedially slightly swollen, posteriorly with strong, transverse impression, distinctly concave in lateral view ( Fig. 19 ); hind margin medially slightly emarginated. Segment 8 and genital capsule small. Pygophore and proctiger slightly asymmetrical. Left paramere reduced. Right paramere ( Fig. 21 ) elongate, curved, distally slender.

Description of macropterous female. – Body length 1.37– 1.49 mm. Pronotal width 0.60–0.67 mm.

Colour as in male, except sternite 7 ventrally brown; in some specimens, dorsum more infuscated.

Pilosity: generally short, but laterotergites 2 with few longer setae, sternite 7 at connexival corner with tuft of long setae and laterotergites 8 and complete posterior edge of tergite 8 with dense brush of long setae.

Legs simple. Abdomen slender, anteriorly without modifications. Tergite 8 forming a sharp edge, dorsal and posterior face forming a right angle; posterior face ca. 2.5 times as wide as long. Proctiger forming a prominent, ventrocaudad directed knob. Most of gonocoxa 1 concealed by sternite 7.

Description of apterous male. – Body length 1.16–1.23 mm. Pronotal width 0.45–0.48 mm.

Colour: Similar to macropterous morph. Head usually orange. Pronotum brown with broad orange margin anteriorly, posterior margin rarely with narrow yellow margin. Tergites and laterotergites variably brownly infuscated. Most commonly, laterotergites, tergite 7, segment 8, and medial areas of tergites 1–3 orange, tergites 4–5 brown, in other specimens tergites 3–6 to 1–6 brown and laterotergites 4–5 also browly infuscated. Tergites 1–3 (–4) more or less frosted.

Pilosity as in macropterous morph.

Legs, abdomen, and genitalia as in macropterous morph. Pronotum much smaller, but long compared with some other species of the genus, medianly ca. 0.8 times as long as head and almost completely covering metanotum, hind margin convex. Sides of abdomen anteriorly subparallel, laterotergites moderately raised throughout. Tergite 7 much larger than preceding tergites, ca. 0.8 times as long as wide and slightly longer than tergites 5 and 6 combined.

Description of apterous female. – Body length 1.17–1.31 mm. Pronotal width 0.48–0.57 mm.

Colour dorsally similar to that of apterous male, but in some specimens dark parts more pronounced and giving a more distinct pattern. Tergites (1–) 2–3 frosted, 4–8 not frosted. Venter and sides as in macropterous female.

Pronotum as in apterous male. Abdomen ( Figs. 22, 23 ) usually very narrow, with sides anteriorly constricted, narrowest at segment 3, slightly convex at segments 5-6 and then again narrowed at segment 7. In such specimens laterotergites almost vertical throughout. In specimens with more swollen abdomen (probably filled with eggs), laterotergites directed more laterad or even totally flat, giving the abdomen a broader appearance. Tergite 7 ca. 0.7 times as long as broad at anterior margin and ca. 1.5 times as long as tergite 6; its sides strongly convergent posteriad. Tergite 8 almost as long as tergite 7, slightly longer than wide, and shallowly concave. Terminalia as in macropterous morph.

Etymology. – From Latin minutissimus; referring to the species’ extremely small size.

Remarks. – The presence of a mesotibial comb of the male ( Fig. 18 ) and the asymmetrical genitalia of the male with a long right ( Fig. 21 ) and a reduced left paramere place M. minutissima in the subgenus Picaultia Distant, 1913 . The new species is one of the smallest in the genus and has a slender body ( Figs. 4, 5 ). Apterous specimens have the dorsum usually orange to light brownish with variably infuscated pronotum and abdomen. The male can be recognized by the concave outline of sternite 7 in lateral view ( Fig. 19 ), by the small genital capsule ( Fig. 20 ), and by the shape of the slender and curved right paramere ( Fig. 21 ). The female can be easily distinguished from other Picaultia species by characteristics of the abdomen: The tergite 8 possesses a dense brush of equally long setae all along its posterior edge which are more than half as long as the tergite length ( Fig. 22 ); in the apterous female, tergite 1 is usually completely frosted, tergites 2–3 discretely, but completely frosted and tergites 4–8 usually not frosted at all.

Distribution. – Malaysia (Langkawi, Selangor) and Singapore.

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. 17–23. Microvelia (Picaultia) minutissima, new species: 17, fore tibia and tarsus of male; 18, middle tibia and tarsus of male; 19, abdomen of macropterous male, lateralview; 20, abdomen of macropterous male, ventral view; 21, right paramere of male, lateral view; 22, abdomen of apterous female, dorsal view; 23, abdomen of apterous female, lateral view.