Diagnosis of the subgenus Allograpta (from Mengual et al. 2009).
Face straight, with low indistinct tubercle of variable size; oral opening about 1.5 to 2 times as long as wide, with oral apex at level of antennal base; antennal pits confluent; plumula well developed or absent; subscutellar fringe distinct or absent; wing partially bare basomedially, with or without apical dark macula; alula broad, about 1.5 times as broad as cell BM; metasternum pilose or bare; abdomen elongate, parallel to slightly petiolate.
A curious species, which in size, black-banded scutellum and black coxae, resembles Ischiodon scutellaris, while in all other characters it agrees with Allograpta javana (=Xanthogramma javanum distinctum), having moreover a broad black facial vitta, mainly black pili on the head, thorax and abdomen, and infuscated wings (from Bezzi, 1928).
Bezzi (1928) described this taxon as Xanthogramma amphoterum, but Thompson and Vockeroth (1989) included this taxon within Allograpta (Allograpta).
Allograpta (Allograpta) amphoterum (Bezzi, 1928).
Bezzi, M. (1928) Diptera Brachycera and Athericera of the Fiji Islands based on material in the British Museum (Natural History). British Museum (Natural History) London. viii + 220 pp. [1928.06.23]
Adapted from original publication (Bezzi 1928).
MALE.
Head: Occiput black, without any dorsal grey macula, but with broadly grey-dusted sides ventrally; posterior eye-borders shallowly sinuous, with argenteous scaly pile, and with black pili above on vertex. Ocellar triangle very narrow, black and black-haired; eyes united for a distance equal to ocellar triangle, with upper interior facets very little enlarged; frontal triangle prominent, black-haired, yellow, with broad shining black macula just above base of antennae, and with shinning black tubercle in middle of lunule. Face yellow, with whitish sides clothed with darkish pile; a broad black median vitta, running from base of antennae to tubercle, and below this much more narrowly to mouth-border; gena yellow, very narrow; proboscis dirty yellowish. Antennae reddish, with basoflagellomere rounded and broadly black on upper border; arista black, bare, rather thick, longer than antenna.
Thorax: shining black dorsally, with complete lateral yellow stripe on each side extending from postpronotum to scutellum; pleurae deep black, with same yellow maculae as in X. javanum distinctum (Allograpta javana); metathoracic spiracular fringes whitish; pili rather long, black on dorsum, pale on pleurae. Scutellum yellow, black-haired, with broad medial black macula. Mesophragma shining black; calypters blackish, with lower calypter whitish towards middle, with black border and black fringe; halteres yellowish. Legs: Coxae and trochanters deep black in type, partly yellowish in Fijian specimen; four anterior legs entirely yellowish with apical tarsi segments blackened; metafemora black on distal half; metatibiae black, with yellowish ring in middle; metatarsi black, with yellowish base; pili on metalegs black; claws yellowish, with black tips, those of front pair quite regular. Wings evenly infuscated in type, but less deeply in Fijian specimen; stigma blackish; veins black, disposed as in X. javanum, that is, with costa ending at wing-tip, vein R4+5 almost straight and cell R4+5 of regular shape; node of vena spuria beyond origin of R4+5 .
Abdomen of same elongate form as in I. scutellaris, clothed with long, pale yellowish pile at sides of base, and with shorter black or blackish pile elsewhere; first tergum yellow, with broad, rounded black macula in middle; second tergum deep black, narrowly shining on posterior margin, with yellow fascia narrowly interrupted in middle; third and fourth terga deep black, narrowly shining on anterior and posterior margins, with entire yellow fasciae, which reach sides and are slightly emarginate on posterior margin; fifth tergum shining black, with yellow fascia on anterior margin, deeply emarginate behind; genitalia shining black and black-haired; ventral membrane translucent, so that dorsal pattern shows through.
FEMALE.
Frons with broad shining black vitta, extending from vertex to lunule and gradually broadened in front; facial vitta as in male; sides of face yellow, with white pile. Thorax, scutellum and abdomen as in male; velvety black fasciae on abdomen narrower, shining parts thus being wider. Legs exactly as in male, with all coxae black. Wings a litlle less infuscated than in male.
unless otherwise stated