Parallygus Melichar

Dai, Wu & Zhang, Yalin, 2012, Revision of the Oriental leafhopper genus Parallygus Melichar (Hemiptera: Cicadellidae: Deltocephalinae) with description of new species, Zootaxa 3157, pp. 41-53 : 42-44

Parallygus Melichar

Parallygus Melichar, 1903: 179 . Type species: Parallygus divaricatus Melichar , by original designation.

Medium sized leafhoppers measuring 5.5–7.5 mm long. Ochraceous with brown to chocolate brown markings; stripe ventrad of lateral carina of pronotum, one submarginal line along basal half of costa bordering yellow band and in contact with large, elongate costal spot, chocolate brown.

Head narrower than pronotum, rather thin anteriorly, angulate at transition of vertex and face; disc of vertex with transverse furrow, polished, longitudinally rugulose, anterior margin beyond furrow shagreen. Face (including eyes) as wide as long, antennal pits shallow, slightly transgressing margins of frontoclypeus, transclypeal sulcus complete, clypellus with concave lateral margins, slightly wider at apex than at base, lora not attaining genal margin. Eyes moderately large overlying anterolateral angles of pronotum. Ocelli large, separated from adjacent eye by distance less than half their diameter. Labium not exceeding prosternum. Pronotum with long carinate lateral margins, anterior margin roundly produced, posterior margin slightly concave; disc polished but with transverse, smooth, irregular ridges, sparingly punctate, about twice (1.75–2.0) as long as head. Scutellum as long as pronotum or slightly longer, surface of scutum shagreen, transversely wrinkled. Forewings with claval veins either connected by one or two cross veins or separate; one cross vein between claval suture and outer claval vein; three subapical cells and four apical cells; inner subapical cell open basally, outer subapical cell small, one reflexed vein arising from outer subapical cell, another one from median subapical cells to costa, rarely from the outer subapical cell ( guttatus ); outer and inner apical cells triangular. Profemur AM row with one preapical macroseta (AM1); AD row of setae present only in basal half, intercalary row with 12–13 long slender setae; AV row with short peg-like setae about 19 in number. Protibia and mesotibia with 4+4 setae. Hind femoral distal setal formula 2+2+1; hind tibial setal formula AD 12, AV 17–20, PD 17–20; metabasitarsus with two rows of five setae on plantar surface, outer row of setae shorter; apical pecten with 6 platellae and one outer short stout seta.

Male tenth segment well developed, sclerotized. Male pygofer fused laterally with valve, with dorsal marginal lobe-like process. Subgenital plates infolded at midlength appearing rounded at caudal margin with prominent macrosetae, anterior part triangular, apically sclerotized and pigmented, with indication of setal bases or with setae. Style with reduced apophysis, thin, plate-like, unpigmented, lodged in infolded area of subgenital plate, oriented almost at 45o angle dorsad, articulated with connective at midlength. Connective with reduced stem, V- or Ushaped, or stem absent, with divided arms that independently articulate with aedeagus. Aedeagus with paired shafts, each with separate gonopore, with or without basal and ventral processes. Gonopores apical or subapical.

Female seventh sternum broader than long with posterior margin truncate or medially slightly emarginate. First pair of valvulae straight, of uniform width for most part except caudal 0.3, sculptured area on distal 0.3 length, proximally with oblique corrugated lines, and distally with overlapping cells ( Figs 2 A–D). Second pair of valvulae arcuate, with dorsal toothed area on distal 0.33 length, teeth prominent with secondary crenulations ( Figs 2 E, F).

Remarks. This genus is externally similar to Platyretus Melichar (see Viraktamath et al. 2008) both in coloration and appearance. In fact, specimens of Parallygus are often mixed up with those of Platyretus in entomological collections. J. Zahniser (personal correspondence) also points out that the African genera, Scaphoidophyes Kirkaldy and Capoideus Theron are also very similar, at least externally to Platyretus and Parallygus , being dark brown dorsally and lemon-yellow or pale ventrally, often with the median part of the scutellum bright yellow and having the lateral margin of the pronotum fairly long, almost as long as the basal width of the eye. In addition, the outer anteapical cell is very small in Parallygus , and even sometimes absent as in Scaphoidophyes .

Despite their external similarities, the male genitalia of the above genera are very different. The male genitalia of Parallygus are specialized; the subgenital plates are infolded so that the distal end of a rather degenerate style is lodged into each infolding of the plate, the connective is either U or V-shaped without stem or with divided arms articulating with the aedeagus independently and the aedeagus has paired shafts with or without a pair of ventral posteriorly directed blade-like processes. The female seventh sternite in Platyretus is trilobed with the median lobe flap-like and showing specialization ( Viraktamath et al. 2008) compared to a simple plate-like seventh sternite in Parallygus .

Parallygus has been assigned to the tribe Athysanini (Metcalf, 1957; Oman et al. 1990) but it differs from other genera of this tribe, including Capoideus , Platyretus and Scaphoidophyes , in having paired aedeagal shafts with two gonopores, the most distinctive feature of the tribe Opsiini ( Emeljanov, 1962) . Recent phylogenetic analyses have failed to support consistently the monophyly of Opsiini and Athysanini , ( Zahniser and Dietrich, 2008, 2010; Dai et al., 2011), but this could be due to a lack of sufficiently informative data and/or low taxon sampling. Moreover, closely related species of some groups vary for certain characters thought to be stable at the tribal level. For example, connectives among species of Paralaevicephalus Ishihara (deltocephaline tribe Paralimnini ) are either racquet-shaped, as is usual for Paralimnini , or Y-shaped ( Xing et al., 2009), which would cause these congeneric species to key out to different tribes. Similarly, the genus Paralampridius Dai, Dietrich & Zhang, closely resembles Lampridius Distant (Opsiini) but lacks the main diagnostic feature of Opsiini : paired aedeagal shafts with two gonopores ( Dai et al., 2011). Also, the paired aedeagi among Deltocephalinae are also found in the genera Masiripius Dlabola and Japananaus Ball of the tribe Scaphytopiini ( Oman et al., 1990) and in some Mukariini. So the tribal placement of Parallygus remains uncertain and is only tentatively retained in Athysanini pending further studies on Deltocephalinae classification.

In addition to the five species dealt with below there are at least three more species represented only by females collected from India (UASB). Female genitalia of one of them are illustrated in Figs 2 A–F. The distributions of the four species in the Indian subcontinent and China are shown in Fig. 8 .

Figures

FIGURE 2. Female ovipositor of undetermined species of Parallygus. A. First pair of valvula, lateral view; B. First pair of valvula showing distribution of sculpturing; C. Details of sculpturing of first pair of valvula in middle region; D. Details of sculpturing of first pair of valvula in the apical region; E. Second pair of valvula, lateral view. F. Second pair of valvula showing arrangement of teeth.

FIGURE 8. Map showing distribution of species of Parallygus in India, Sri Lanka and China.