Gryllacris (Gigantogryllacris) bilineata, 2018

Ingrisch, Sigfrid, 2018, New taxa and records of Gryllacrididae (Orthoptera, Stenopelmatoidea) from South East Asia and New Guinea with a key to the genera, Zootaxa 4510 (1), pp. 1-278 : 63-64

publication ID 10.11646/zootaxa.4510.1.1

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Gryllacris (Gigantogryllacris) bilineata

sp. nov.

Gryllacris (Gigantogryllacris) bilineata View in CoL sp. nov.

Figs. 11I View FIGURE 11 , 12O View FIGURE 12 , 15 View FIGURE 15 J–L

Material examined. Holotype (male): Papua New Guinea: Madang, Baiteta , elev. 57 m (5°1'S, 145°45'0''E), 30.iv.1995, leg. Olivier Missa (FOG AR 22)—(Brussels RBINS). GoogleMaps

Diagnosis. G. bilineata sp. nov. and G. ligulata sp. nov. differ from other species of the subgenus Gigantogryllacris by the colorless hind wings without any traces of dark bands along the cross-veins. G. bilineata is very similar to G. ligulata in general appearance and coloration, but differs by the following characters: Face wider, more oval, mandibles shorter with lateral margin not distinctly concave; tegmen wider (length: width 34:12 instead of 34: 10.5 mm); Ninth abdominal tergite at transition from dorsal to apico-ventral surface with a distinct cone and below that cone with a pair of transverse narrow maculae, both missing in the other species; the pair of compressed and bent apical projections of ninth tergite is inserted more proximal and lateral, thus that even when the subgenital plate is wide open and the ninth tergite is pressed dorsal they cannot be seen from behind without further manipulation. The conically projecting surface of the ninth abdominal tergite resembles somewhat the condition in G. compromittens Brunner, 1898 but is more pronounced than in that species, another difference is the pair of black marks on the underside of the cone and the black projections from the apical margin are inserted more proximad and cannot be seen from behind without manipulating the specimen while visible from behind in G. compromittens .

Description. Medium large to large species. Head: Face ovoid; forehead nearly smooth with scattered impressed dots and very fine transverse riffles (formerly conserved in alcohol); fastigium verticis wider than scapus, separated by a fine transverse suture from fastigium frontis; ocelli distinct; subocular furrows distinct ( Fig. 12O View FIGURE 12 ). Abdominal tergites two and three each with two rows of stridulatory pegs (3, 8; 9, 12; n = 1).

Wings surpassing hind knees ( Fig. 11I View FIGURE 11 ). Tegmen: Radius releases RS between basal third and mid length of tegmen, both branches forked in apical area. Media anterior fused in basal area with radius, divides behind end of basal third; media posterior absent; cubitus anterior divides little before mid-length of tegmen into CuA1 and CuA2; cubitus posterior undivided, free throughout; with 4 anal veins.

Legs: Fore coxa with a spine at fore margin; fore and mid femora unarmed; fore and mid tibiae with 4 pairs of large ventral spines and one pair of smaller ventral spurs; hind femur with 5–7 external and 6–7 internal spines on ventral margins; hind tibia with spaced spines on both dorsal margins, ventral margins with one pre-apical spine; with 3 apical spurs on both sides.

Coloration. General color uniformly light brownish, frons and rim of pronotum but not at fore margin black; with a small black spot at genicular area of all legs; ventral spines of hind femur and dorsal spines of hind tibia black. Face including anterior area of vertex and basal segments of antennae black; compound eyes light, ocelli light yellow; lateral and ventral areas of clypeus brownish yellow. Tegmen yellowish semi-transparent, towards base cells faintly infumate; veins and veinlets yellow; hind wing semi-transparent greyish; veins dark yellow, cross-veins yellow.

Male. Eighth abdominal tergite prolonged, with lateral areas nearly rectangularly bent to dorsal surface, although the angle itself is gradually curved. Ninth abdominal tergite strongly curved down from sub-flattened dorsal to lateral surfaces, at tip rounded and in middle strongly bent ventro-proximad, more laterally apico-ventrad; apical surface in about dorsal half in middle strongly swollen, forming a projecting cone and at lower margin of swelling with a pair of transverse black sclerotizations, surface bent ventro-proximad and strongly furrowed; on proximate margin of ventro-apical surface with a compressed and except at base black projection at each side; projections with approaching margins to about two thirds of their lengths, then bent proximad and widening to truncate tip; somewhat more laterally there is a compressed, black (except in basal area) projection at each side bent proximad in subapical area [the projections have been artificially pressed backward to make them visible; the folds of the margin of the tergite at their base are a result of that handling] ( Figs. 15 View FIGURE 15 J–L). Tenth abdominal tergite reduced to a short transverse area mediad of bases of cerci. Epiproct triangular with concave surface and rounded tip; paraproctes prominently projecting between remnants of tenth tergite. Subgenital plate wide in about basal half, then strongly narrowed and at tip bilobate; styli inserted at apico-lateral angles of wide area and largely surpassing tip of plate.

Female unknown.

Measurements (1 male).—body w/wings: 44; body w/o wings: 30; pronotum: 8.5; tegmen: 34; tegmen width: 12; hind femur: 23 mm.

Etymology. The new species is named for the pair of swollen black strokes at the tip of the ventral hind margin of the ninth abdominal tergite.


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