Siamiassus, Dai, Wu, Dietrich, Christopher H. & Zhang, Yalin, 2015

Dai, Wu, Dietrich, Christopher H. & Zhang, Yalin, 2015, A review of the leafhopper tribe Hyalojassini (Hemiptera: Cicadellidae: Iassinae) with description of new taxa, Zootaxa 3911 (1), pp. 1-142 : 31-32

Siamiassus gen. nov.

Type species: Siamiassus constanti sp. nov.

Pale olive green with brown markings ( Fig. 5 C, D). Body robust, weakly depressed. Head in dorsal view much narrower than pronotum ( Fig. 5 C); crown short, rounded to face, anterior and posterior margins parallel; vertex and frontoclypeus transversely rugose; face slightly broader than tall; gena broadly rounded, obtusely emarginate below eye; rostrum slender, extended slightly beyond front coxa; anteclypeus weakly convex, slightly tapered from base to apex, apex truncate, even with lower margin of gena; lorum narrow, well separated from lateral and ventral margins of gena, with basal fourth of mesal margin bordering frontoclypeus; frontoclypeus flattened medially; antennal ledge well developed, narrow, transverse; lateral frontal suture extended short distance above antennal ledge, not reaching ocellus; ocellus large, separated from eye by one ocellar diameter. Pronotum strongly convex, with conspicuous transverse rugae; lateral margins long, strongly carinate, evenly divergent posterad. Exposed part of mesonotum and scutellum together as long as pronotum, transversely rugose, scutellar suture arched anterad, scutellum convex basally with apex acuminate ( Fig. 5 C, D). Forewing venation obscure in basal half; membrane semiopaque, conspicuously marked with numerous small black spots, setae short and inconspicuous; appendix much broader than inner apical cell; vein R with ca. eight branches; three closed anteapical cells present; apical cells elongate, parallel-sided, progressively longer toward trailing edge of wing, bases aligned; posterior branch of CuA connected to margin at apex of clavus; clavus broadly truncate apically; texture of inner apical cell same as that of appendix and adjacent cells ( Fig. 23 A). Hind wing with RP confluent with MA distally. Front femur with pair of dorsoapical macrosetae; AM without conspicuous setae except AM1 well developed; intercalary row with dense patch of stout pale setae; AV with numerous longer setae scattered in basal half; PV with few stout setae near base; tibia flat and bicarinate dorsally, rows AD and PD 5+5. Mesothoracic tibia also flattened and bicarinate dorsally. Hind femur macrosetal formula 2+2+1; tibial rows PD, AD, and AV with 21, 12, and 14 macrosetae, respectively; tarsomere I without enlarged dorsoapical setae or rows of plantar setae, pecten with 5 platellae.

Male abdominal apodemes poorly developed. Sternite VIII twice as long as sternite VII, broader than long, lateral margins roundly tapered posterad, apex truncate. Genital capsule with ventral part completely concealed by sternite VIII in repose, with only anal tube visible. Pygofer with tergite well sclerotized forming unbroken ring continuous with posterolateral margin, roundly produced and forming shelf over anal tube; posterior margin with few short spatulate setae; basolateral setal group with several fine tapered setae and few spatulate setae; anterodorsal margin in lateral view emarginate along intersegmental membrane; posterior margin long and straight, with process arising dorsoapically, extended basoventrad and terminating in hammerlike apex, process free from pygofer margin only at apex; intersegmental membrane between anal tube and aedeagus partially sclerotized with few short setae ( Fig. 20 A). Subgenital plates short, broad, depressed, fused medially at base, free in distal half with small dorsal preapical tooth, few short fine setae at apex and preapically near lateral margin ( Fig. 20 B). Valve long and narrow, broadly fused to pygofer at base, posterior margin truncate ( Fig. 20 B). Connective amorphous, membranous ( Fig. 20 A, C). Style vestigial, consisting of short, sclerotized, digitiform projection attached to atrium of aedeagus by membrane. Aedeagus simple, tubular, U-shaped in lateral view; apex acuminate in lateral and posterior view; atrium with prominent ventrolateral lobes; gonopore preapical on posterior surface ( Fig. 20 C, D). Female unknown.

Notes. The genus name, which is masculine, was formed by combining Siam, a former name for Thailand, with Iassus , type genus of Iassinae. The new genus is unique among known leafhoppers in having the style almost completely vestigial, represented only by a small, partially membranous, digitiform projection. The broad forewing appendix, small black spots on the forewing membrane, fused subgenital plates and membranous connective suggest that the new genus is most closely related to Siniassus, but the latter genus differs in having well-developed styles. The type species of Siamiassus is also much larger and less strongly depressed than any known species of Siniassus, and has a well-developed pygofer appendage. The pygofer appendage of Siamiassus is similar to that of some New World iassine genera (e.g., Penestragania ) in arising posterodorsally and extending anteroventrad, but unlike that of any known Old World genus.

Figures

FIGURE 5. Dorsal and lateral habitus. A, B, Lamelliassus chiangmaiensis sp. nov.; C, D, Siamiassus constanti sp. nov.; E, F, Trocniassus shaanxiensis sp. nov.; G, H, Trocniassus henanensis sp. nov.

FIGURE 20. Siamiassus constanti sp. nov. A. Genital capsule, lateral view; B. Genital capsule, ventral view; C. Aedeagus, lateral view; D. Aedeagus, ventral view.

FIGURE 23. Forewing. A. Siamiassus constanti; B. Lamelliassus chiangmaiensis.