Vilargus triquetricans, Stiller, 2010

Stiller, M., 2010, Revision of Vilargus Theron (Hemiptera: Cicadellidae: Deltocephalinae) from South Africa, Zootaxa 2674 (1), pp. 1-25 : 14-20

Vilargus triquetricans sp. n.

( Figs 22–27 , 92–103 ).

Diagnosis. Aedeagus with parallel-sided process arising laterally from base of shaft, length variable (as long as or shorter than shaft). Plate acutely triangular, apex angled dorsad, of variable length. Female sternite 7 posterior margin with short, blunt, median ligula.

Etymology. Latin, tri, three, quetra, suffix meaning angle, for the triangular shape of the subgenital plate.

Colour. Male, female and nymph. Ochraceous, sometimes with more distinct darker fuscous markings dorsally ( Figs 22, 23, 25 (fuscous markings); nymph, Fig. 27 , all specimens from Orrie Baragwanath; Figs 24, 26 , specimens from Serala (few or without fuscous markings).

Male. Dimensions. (n=23) Length from apex of vertex to apex of tegmina 2.0– 2.2 mm, length from apex of vertex to apex of abdomen 2.4–2.6 mm, median length of vertex 0.4–0.5 mm, length of vertex next to eye 0.3 mm, length of pronotum 0.3 mm, width of head 0.7–0.8 mm, width of pronotum 0.7 mm, diameter of ocellus 28 µm, ocellocular distance 36–47 µm.

Genitalia. Aedeagus, laterally, dorsal apodeme angled or curved posteriad, shaft arising from preatrium, C-shaped, wide basally, tapered toward apex ( Fig. 93 ). Aedeagus, posteriorly, dorsal apodeme semicircular, shaft somewhat depressed, asymmetrical, single spine arising laterobasally from shaft ( Fig. 92 ). Shaft and spine variable ( Figs 92, 96, 97, 98 ), three forms recognized: Aedeagus, veiwed ventrally,

a. Spine as long as shaft, curved widely, tapered uniformly ( Figs 92, 93 ); apex of shaft asymmetrical, acute; gonopore subapical; specimens from Strydpoortberg.

b. Spine about half as long as shaft with apex compressed ( Figs 96, 97 ); apex of shaft asymmetrical, laterally with two unpaired, variable triangular processes, apex deflected laterad; gonopore apical ( Figs 96, 97 ); specimens from Orrie Baragwanath Pass.

c. Spine slightly shorter than shaft, digitate; opposite side with very short rounded protrusion ( Fig. 98 ); apex asymmetrical, with long, acute subapical spine, apex curved slightly laterad; gonopore apical ( Fig. 98 ); specimens from Serala Forestry Station.

Connective symmetrical, width across stem and arms similar; stem one third length of arms, constricted at base ( Fig. 94 ). Style ( Fig. 95 ) with anterior medial lobe extending beyond base of apophysis, acutely angled to base; apophysis acute. Plate ventrally acutely triangular; apex curved or bent dorsad at right angle, apex of variable length: about one quarter as long as length of plate (specimens from Serala Forestry Station and Strydpoortberg), or about one third as long as length of plate ( Fig. 99 ) (specimens from Orrie Baragwanath Pass); aedeagus in cleared specimen, when viewed as in Fig. 99 , with spine always on right side. Pygofer, laterally, rectangular ( Fig. 101, 102 ); dorsally as in Fig. 100 . Pygofer lobe variable, rounded or triangular, arising apically or subapically from dorsoposterior margin of pygofer, about half as wide across base as width of pygofer ( Figs 101, 102 ).

Female. Dimensions. (n=11) Length from apex of vertex to apex of tegmina 2.2–2.4 mm, length from apex of vertex to apex of abdomen 2.8–3.2 mm, median length of vertex 0.5 mm, length of vertex next to eye 0.3 mm, length of pronotum 0.3 mm, width of head 0.8–0.9 mm, width of pronotum 0.7–0.8 mm, diameter of ocellus 28 µm, ocellocular distance 39–50 µm.

Genitalia. Sternite 7 posterior margin with short, blunt ligula ( Fig. 103 ).

Material examined. Holotype male. South Africa. Limpopo Province. Orrie Baragwanath Pass , 24°08ʹS, 30°11ʹE, 1361 m, 8.xi.2005, M. Stiller, DVac, short moribund grass ( SANC) . Paratypes. 22♂, 14♀.

Limpopo Province. 6♂, 2♀, Serala Forestry Station , fire lookout, 24°00ʹS, 29°57ʹE, 2029 m, 7.xi.2005, DVac, moribund grass, including Festuca sp .; 2♂, Strydpoortberg, SE Polokwane, 24°04ʹS, 29°49ʹE, 1800 m, 13.xii.2003, sweeping, grass on sandstone outcrop; 1♂, 1♀, Strydpoortberg, SE Polokwane, 24°03ʹS, 29°48ʹE, 1900 m, 13.xii.2003, sweeping, grass on S-slope, sandstone; 13♂, 11♀, ibid., holotype; all collected by M. Stiller ( BMNH, SANC) .

Remarks. Vilargus triquetricans has a unique acutely triangular plate, with narrow dorsally angled apex, of variable length and the aedeagus that is variable in its structure, but has a laterobasal spine and C-shaped shaft. Three forms are recognized, but that are considered as intraspecific variation. The structure of the aedeagus of this species corresponds well with that of the genus, and therefore does not justify placement in another genus. The sternite 7 of associated females is least typical of the genus, and no corresponding intraspecific variation is visible, and is considered of secondary importance in the placement of this species.

The plate in specimens from Orrie Baragwanath Pass has the apical third angled dorsad ( Fig. 102 ). Specimens from Serala and Strydpoordberg have the apical quarter angled dorsoposteriad ( Fig. 101 ).

The aedeagus in the Orrie Baragwanath Pass specimens has the basal process shorter than the shaft and compressed, and has the apex tapered and ending in the gonopore ( Figs 96, 97 ).

The aedeagus in the Serala specimens has the basal process shorter than the shaft, but tubular, and not compressed. It has the apex with a lateral, blunt spine and the gonopore opening in a short tube. Additionally there is a short stub at the base of the shaft, opposite the elongate basal process ( Fig. 98 ).

The aedeagus in the Strydpoortberg specimens has the longest basal process, that is not compressed, and the apex of the shaft has a more elongate lateral spine, and the gonopore is flush with the apex of the shaft, and does not open at the end of a tube ( Figs 92, 93 ).

There are no differences in the connective and style between the male specimens from these three localities.

No other species of Vilargus has a similar acutely triangular plate in the male. Vilargus budenticans was also found at Serala Forestry Station and appeared to be more common than V. triquetricans (62 specimens of V. budenticans versus 8 specimens of V. triquetricans ). These two species are readily distinguished by the shape of the plate of the male, and the shape of the sternite 7 of the female.

The structure of the plate of Pravistylus varicudiscus Stiller, 2010 is similar to that of V. triquetricans ( Fig. 99 ). In both these species the apex of the plate is similar in shape with the apex right-angled dorsad. However the known distributions of these two species differ and other structures of the male and female differ significantly.

Figures

FIGURES 22–27. Vilargus triquetricans sp. n. Habitus. 22–24, male; 25–26, female; 27, nymph (scale = 1 mm).

FIGURES 92–103. Vilargus triquetricans sp. n. Male and female genitalia. 92, aedeagus, ventrally; 93, aedeagus, laterally; 94, connective; 95, style; 96, aedeagus, ventrally; 97, aedeagus, laterally; 98, aedeagus, laterally; 99, plate; 100, pygofer, dorsally; 101, pygofer, laterally; 103, pygofer, laterally; 103, female, sternite 7 (scale = 0.1 mm).