Orseolia orientalis (Felt)

[Figs 30 a–o]

Orseoliella orientalis Felt, 1921d: 90 .

Orseolia orientalis (Felt): Gagné (1973: 507), new combination; Gagné (1985: 147), revision.

Material examined. Lectotype male, designated by Gagné (1985: 148), paralectotypes female and pupa, reared from leaf sheath gall on Oplismenus compositus P. Beauv., Bogor, Java, vi-1920, Felt type #a3152. The types are whole, cleared mounts on two separate slides, remounted by RJG, entire except for most circumfila being dissolved and mostly unrecognizable, and the 2 and 3 terminal male flagellomeres are missing.

Description. Adult. Wing length 3.1 mm in male, 3.5 in female ( Gagné 1985). Vein R 1 slightly bowed, joining C posteriad of wing apex [Fig. 30c]. Palpus 4-segmented [Fig. 30e]. Tarsal claws as for genus [Fig. 30d].

Male. Flagellomeres [Figs 30g, h, i] with short circumfilar loops. Terminalia [Fig. 30f]: gonocoxite narrow beyond bulbous base; gonostylus long, cylindrical, widened just proximad of tooth, setulose at basal 1/4, carinate beyond; cerci tapered caudally; hypoproct much longer than cerci, convex apically; aedeagus longer than and nearly as wide as hypoproct, conical apically, with asetose sensilla terminally.

Female. Flagellomere nodes narrowed at basal third, circumfila slightly irregular [Fig. 30j]. Tergum 10 with setae along caudal margin, cerci ovoid, setae narrower towards apex, thick sensory setae slightly longer than adjacent setae [Fig. 30k].

Pupa. Antennal horns bifid, one part longer, wide and serrated apically, the other shorter, narrow, pointed and smooth [Fig. 30o]. Prothoracic spiracle long, slightly tapered and bowed, widened and serrate at apex, trachea reaching apex [Figs 30m, n]. Tergal spines short and broad [Fig. 30l].

Larva unknown.

Remarks. This distinct species differs from the other congeners in the long, narrow gonostylus and wide aedeagus and shape of the pupal antennal horns. Two other, differently shaped, leaf sheath galls on O. compositus by unknown Cecidomyiidae . occur in Indonesia (DvLR & DvL 1926, galls No 56, 57).

Biology. This species causes a leaf sheath gall on Oplismenus compositus (Poaceae), described by DvLR & DvL (1926, gall No 55, Figs 32, 33) [Figs 30a, b]. The leaf sheath of the youngest leaf is changed into a tube emerging among other, unchanged leaves [Fig. 30a]. The leaf blade is developed though not quite normal at the end of the tube, and in this case the occurrence of the leaf blade is a feature of the gall, although that feature occurs occasionally with leaf sheath galls of other species. When older, the gall tube grows very quickly. There is a weak spot about a third of the total length from the tip of the gall where the gall breaks in two, allowing the gall midge to emerge [Fig. 30b].

Geographical distribution. This species is currently known only form its type locality in Java: Bogor, alt. 250 m, v and vi-1920 (Felt 1921d; DvLR & DvL 1926).