FNZ 20 - Bibionidae (Insecta: Diptera) - Morphology
Harrison, RA 1990. Bibionidae (Insecta: Diptera). Fauna of New Zealand 20, 28 pages.
(
ISSN 0111-5383 (print),
;
no.
20.
ISBN 0-477-02595-1 (print),
).
Published 13 Nov 1990
ZooBank: http://zoobank.org/References/B52BAEA5-8E92-48C2-88FD-C08826C7DCAA
Morphology
New Zealand examples of the subfamily Bibioninae are the main source of the following generalised morphological description of the family. Other sources are from worldwide literature on bibionids. The terminology used is standard for Diptera.
The body (Fig. 1) shows varying degrees of hairiness, and varies in length from 2.0 mm to 16.0 mm.
The head (Fig. 1 and 2) is holoptic in males. The rostrum (the portion of the head anterior to the eyes) is either well developed and produced distinctly beyond the base of the antennae or is not or scarcely developed beyond the antennal base; in length it is equal to the lower division of the eye in males, or is equal to or longer than the eye in females, or in both sexes is only half the length of the eye. The antennae have a variable number of segments - up to 16 have been recorded - with fusion of segments sometirnes apparent, reducing the number of distinguishable segments beyond the pedicel; the pedicel is flattened, and its distal segment is often distinctly longer than the others. The mouthparts have labella usually as a prominent structure, and often hairy; the proboscis is never much elongated; and the palpi are 3-5-segmented. The round or reniform eyes are larger in males and sometimes divided into distinct areas of different-sized ommatidia, the smaller ones ventral. The ocelli are strong, and the ocellar triangle is distinct, and sometimes raised above the level of the eyes.
The thorax (Fig. 1 and 3) lacks sutures. The pronotum has two comb-like transverse rows of strong or fairly strong spines which are variable in number, colour, and strength. The mesonotum is bare, or bears longitudinal rows of hairs embedded in or adjacent to two longitudinal sulci and on the lateral margins. The pleurites are generally bare. The scutellum (Fig. 3) has a tuft of apical setulae.
The legs have the coxae bare or with a few hairs or minute pubescence, and the trochanters with fine hairs. The femora are elongate, sometimes enlarged towards the apex, and occasionally grooved. The fore tibiae (Fig. 9-13) have spines, varying in number and strength, at the apex and on the middle third of the posterodorsal surface. The fore tarsus and middle tibia and tarsus are normal, but the hind tibia (Fig. 14-17) may be normal or swollen, especially towards the apex, and sometimes has an apical spur; the tarsal segments are sometimes enlarged. The empodium and pulvilli (Fig. 4) are equally strong, or the empodium is absent in some species.
The wings (Fig. 18-22) have the membrane usually clear, but when not so then the shading is more prominent anteriorly, but with transverse clear areas on either side of the stigma. The anterior veins are darker than the posterior veins. A stigma is usually present at the apex of R1 . Venation is normally as in Fig. 21, but with modifications usually in the form of deletions of portions of M1 and M2 and/or loss of m-cu . There is no discal cell, and at most a single complete anal vein reaches the wing margin. The anal cell is rarely closed. The costa does not extend to the posterior margin but ends close to the wing apex. The R veins bear dorsal hairs which are either few and weak or numerous and strong; if the latter, then their length equals or exceeds the distance between them.
The abdomen is of 7-9 segments, elongate, and more or less cylindrical and hairy. The male terminalia (Fig. 5 and 23-30) have the terminal stemite supporting a pair of claspers, the hairiness and shape of which is variable, and the terminal tergite supporting a pair of cerci. The female terminalia (Fig. 6 and 7) have the posterior sternite and tergite bearing a pair of lobes and cerci respectively.