Sweta, Viraktamath & Dietrich, 2011

Viraktamath, C. A. & Dietrich, C. H., 2011, A remarkable new genus of Dikraneurini (Hemiptera: Cicadomorpha: Cicadellidae: Typhlocybinae) from Southeast Asia, Zootaxa 2931 (1), pp. 1-7 : 1-2

Sweta gen. n.

Type species: Sweta hallucinata sp. n.

Head (Figs. 1–3) narrower than pronotum, short and broad, of uniform length throughout, strongly elevated above level of pronotum. Ocelli absent, vestiges present as paired pits on face well ventrad of crown margin, closer to eyes than to each other. Face longer than broad, in profile rather convex, weakly depressed. Clypellus broad at base, projecting beyond margin of gena, broader and more convex in male than in female. Frontal sutures reaching ocellar pits. Rostrum tapered, extended to middle coxae. Pronotum (Figs. 1–2) widened posteriorly, densely but finely punctate, extending beyond anterior margin of eyes anteriorly and to scutellar suture posteriorly, 1.2 times as wide as long, disc strongly convex with slight median posterior emargination; distinct submarginal furrow present along anterior and lateral margins; lateral margins long, carinate. Forewing (Fig. 4) widened gradually toward apex, widest at 0.66 length, without closed anteapical cells, R with two branches originating slightly distad of midlength, posterior branch strongly curved and sinuate toward apex; M with anterior branch strongly sinuate distally; inner apical cell narrow, elongate, gradually tapered; clavus with one indistinct vein; appendix absent. Hind wing (Fig. 5) with submarginal vein complete but weakly developed along costal margin; veins RP and MA confluent distally; CuA and MP completely confluent (CuA appearing unbranched); anal vein not forked. Front femur with dorsoapical pair of macrosetae; AM 1 large, on ventral margin; intercalary row with 4 large basal setae and 7 smaller setae more distad; tibia row AV with 8 macrosetae. Middle femur with only PD 1 developed; tibia without preapical macrosetae. Hind femur macrosetae 2+1; tibial chaetotaxy PD: 10–12, AD: 8–11, AV: 4, PV: ~28, PV setae capitate except 3 larger, tapered setae near apex; hind basitarsus (Fig. 6) as long as tarsomeres II and III combined, with dorsoapical pair of macrosetae and single enlarged ventromedial seta, acutely pointed distally, lacking apical transverse row of spines and platellae.

Male abdomen (Fig. 7) with apodemes of sternum III well developed. Pygofer (Fig. 8) with tergum long and well sclerotized, lobes short, irregularly rounded distally, with short, fine setae distributed sparsely over distal half, appendages absent. Tergum X (Fig. 8) massive, well sclerotized, extended ventrolaterad into pair of acuminate processes. Valve (Figs. 8–9) quadrate, articulated to pygofer. Subgenital plate (Figs. 8–9) depressed in basal half, compressed distally, triangular in ventral view, with 3–4 macrosetae in oblique row near midlength and small, fine setae scattered over distal half. Style ( Fig. 12 ) slender throughout length, apodeme short, apophysis elongate and nearly straight, preapical lobe poorly developed, apex hooked dorsad and acuminate, with preapical heel, shaft of apophysis with few sensilla and single seta preapically. Connective ( Fig. 11 ) not present as distinct sclerite, apparently fused to aedeagus and transverse. Aedeagus ( Figs. 10–11 ) symmetrical, dorsal apodeme weakly developed, preatrium short, shaft compressed, with paired subapical processes, gonopore preapical on posteroventral surface.

Female ovipositor with first valvula sculpturing strigate ( Figs. 14–15 ), striae reaching dorsal margin, arranged in three tiers distally. Second valvulae ( Figs. 16–19 ) strongly curved but not sigmoid distally, moderately broad throughout, with troughlike excavation at base of toothed distal blades; right and left second valvulae asymmetrical, teeth larger with secondary dentition on right valvula ( Fig. 17 ) compared to weaker teeth lacking secondary dentition on left valvula ( Fig. 19 ); additional row of teeth present submarginally, closer to dorsal margin on left valvula compared to those on right valvula.

Remarks. Sweta is easily distinguishable from all other known Typhlocybinae in having the pronotum enlarged, strongly convex, and extended to the scutellar suture, and the crown of the head strongly elevated above the anterior margin of the pronotum. Its small size and broad, tectiform forewing with elongate, sinuate distal segments of veins R and M, give the new genus a superficial resemblance to Psyllidae . Among other known macropterous leafhoppers, only Signoretiinae (=Phlogisinae, Dietrich 2005) have the pronotum extended to the scutellar suture. Sweta differs from Signoretiinae in several important respects (see Discussion below).

The female genitalia of Typhlocybinae have not been studied comprehensively; thus, the significance of the characters described above for the ovipositor of Sweta is unknown. A recent comparative study of species of European Empoascini indicates that Sweta has an ovipositor very similar to that of Empoasca pteridis (Dahlbom) (see Demichelis et al. 2010: Figs. 2D, 3D).

The new species upon which the genus is based appears to be widespread but very rare. The three specimens from Thailand were found only after a search of>3,000 Malaise trap samples containing>500,000 specimens, and only one other specimen, a female from northeastern India, has been found in museum collections .

The genus name is derived from the Sanskrit sweta, meaning “white”, and refers to predominantly white color of the insect and is to be treated as feminine noun.

Figures

FIGURES 10–19. Sweta hallucinata: 10, aedeagus, lateral view; 11, same, posteroventral view; 12, style, ventrolateral view; 13, female abdominal sternite VII; 14, first valvula, lateral view; 15, detail of same; 16, right second valvula; 17, detail of same; 18, left second valvula; 19, detail of same.