Sweta hallucinata, 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 : 3-6

Sweta hallucinata sp. nov.

Figs. 1–21

Milky white to pale yellow. Forewing cells rather clouded with faint pale brown; distal portions of tarsi dark brown ( Fig. 19 ). Male abdomen with 3S apodemes slightly divergent, extended to midlength of segment IV (Fig. 7); aedeagus with ventral preapical processes gradually recurved in lateral view ( Fig. 10 ), straight and slightly divergent from shaft in ventral view ( Fig. 11 ); distal processes extended posteroventrad in lateral view; extended laterad and slightly basad in ventral view; shaft apex abruptly and obliquely tapered in lateral view. Other features as in generic diagnosis.

Female genitalia. Seventh sternite ( Fig. 13 ) broadly roundly produced caudally.

Measurements. Male 3.5–3.8 mm long, 0.75 mm wide across eyes, 0.8 mm wide across hind margin of pronotum. Female 3.8–3.9 mm long, 0.8 mm wide across eyes, 0.9 mm wide across hind margin of pronotum.

Material examined. Holotype ♂ THAILAND: Phetchabun, Khao Kho NP, mixed deciduous forest at Ta Phol river , 16º32.546'N 101º2.501'E, 274m, Malaise trap 5–12.xi.2006, Somchai Chachumnan & Saink Singhtong T970 ( QSBG) . Paratypes: 1 ♀ THAILAND: Lampang, Chae Son NP behind visitor center 18º50.075'N 99º28.433'E 421m, Malaise trap 1–8.ix.2007, Bunruen Kwunnui & Acharaporn Sukpeng T2832 ( QSBG) ; 1 ♂ THAILAND Lampang, Chae Son NP Huay Yen 18º49.924'N 99º28.652'E 419m, Malaise trap 1–7.xi.2007, Bunruen Kwunnui & Acharaporn Sukpeng T2837 ( INHS) ; 1 ♀, INDIA: Mizoram: Aizawl , 18.xi.1981, C.SW. Wesley ( BMNH) .

Etymology. The species name is derived from the Latin hallucinor, meaning “dream” and refers to the unusual and remarkable appearance of the new species.

Discussion. Discovery of the new genus described above is important because it provides further evidence of a relationship between the leafhopper subfamilies Typhlocybinae and Signoretiinae .

Signoretiinae is a small, poorly known subfamily of leafhoppers, apparently restricted to the Old World tropics. The group was previously uniquely defined within Cicadellidae based on the enlarged pronotum that extends to the scutellar suture. Other leafhoppers, with the exception of a few groups with reduced wings, have the pronotum relatively short, such that part of the mesonotum anterad of the scutellar suture is exposed.

A morphology-based phylogenetic analysis of Cicadellidae ( Dietrich 1999) placed Signoretiinae in a clade together with Cicadellinae (sensu stricto), Evacanthinae , Mileewinae and Typhlocybinae and a recent, more detailed analysis of this lineage ( Dietrich 2004) placed Signoretia Stål as sister to a clade comprising Typhlocybinae + ( Mileewinae + Tinterominae).

Signoretiinae has mixed morphological affinities to these taxa. It is similar to most Cicadellinae sensu lato in having the frontoclypeus inflated (an indication of xylem feeding), the ocelli on the crown, and the female second valvulae with the toothed section occupying more than half its length, but resembles Evacanthinae (tribe Evacanthini ) in having a complete median longitudinal carina on the frontoclypeus and the ocelli in submarginal depressions on the crown. Similarities to Typhlocybinae and Mileewinae include the reduced forewing venation (R two- branched and crossveins r-m1 and m-cu2 absent), the tapered first hind tarsomere, and the strongly curved ovipositor.

Although Sweta resembles Signoretia in having the pronotum enlarged and the forewing veins sinuate distally, the new genus is clearly referable to Typhlocybinae based on its small size, vestigial ocelli, absence of closed preapical cells in the forewing, acuminate first hind tarsomere, and asymmetrical female second valvulae. Table 1 provides a comparison of Sweta , the apparently related dikraneurine genus Anaka Dworakowska & Viraktamath , and Signoretia Stål , indicating that although the Sweta and Signoretiinae share one putative synapomorphy that does not occur in other Typhlocybinae--the enlarged pronotum--it shares many more synapomorphies with Typhlocybinae that do not occur in Signoretia . A detailed phylogenetic analysis will be needed to further elucidate the relationship between Signoretiinae and Typhlocybinae in light of the discovery of Sweta , which is morphologically intermediate between these two subfamilies.

Sweta may be placed with confidence in Typhlocybinae based on its acuminate first hind tarsomere and in the typhlocybine tribe Dikraneurini based on its long, subparallel sided forewing inner apical cell, and hind wing with the submarginal vein complete and veins RP and MA confluent. Other features consistent with Dikraneurini are the vestigial ocelli and the triangular male subgenital plate with few lateral macrosetae. The absence of pygofer processes and presence of ventrolateral processes on segment X are unusual among dikraneurines; the latter feature also occurs in the Indomalayan dikraneurine genus Golwala Dworakowska but is more common in the typhlocybine tribe Empoascini . The slender style with footlike apex is also unusual for this tribe; most dikraneurines have the style short and broad with a well developed preapical lobe. The unbranched anal vein of the hind wing is rare among Old World dikraneurines, most of which instead resemble Dikraneura in having this vein forked preapically. Most Neotropical dikraneurines have the vein unbranched, but among described Old World dikraneurines, this feature has been reported only in Kalkiana Sohi, Viraktamath & Dworakowska , Motschulskyia Kirkaldy and Trifida Thapa & Sohi.

In having the aedeagus fused to the connective, Sweta resembles the bamboo-feeding dikraneurine genera Anaka , Apetiocellata Sohi and Trifida . Among these genera, Sweta is somewhat similar to Anaka in general habitus in that the body is not depressed as in most other dikraneurines and the orientation of the face is nearly vertical (see Dworakowska and Viraktamath 1975: Figs. 1–3).

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.