A Peculiar Wing Structure of Hydrellia tritici Coq.
[Read before the Auckland Institute, August 22, 1950; received by the Editor, August 24, 1950]
A fly, Hydrellia tritici Coq.,* captured by the author at Brown's Bay, Auckland, on November 7, 1948, was found to possess a peculiar lobe-like appendage on each wing. This abnormality was apparently responsible for the sluggish and awkward movements that first caused the insect to be noticed.
The purpose of this note is to place the discovery on record.
H. tritici, redescribed by Tonnoir and Malloch (1926), is a small fly 2 mm. long, recorded from South Island localities, but also common in Auckland. The Brown's Bay specimen has wings in which the distal break in the costa, at the apex of the first longitudinal vein, is enlarged, and here a lobe-like structure arises. It branches off from the anterior margin of the wing at an angle of approximately 20μ, is 0·8 mm. long and increases in width from 0·15 mm. at the wing margin to 0·25 at the apex. The lobe consists of wing membrane surrounded by a vein similar to the costa. It has a weaker mid-vein extending from near the base of the lobe to the apex and it is folded slightly along the line of this mid-vein. Apart from the wings, the Brown's Bay specimen appears to be normal. The wing of a normal H. tritici and that of the Brown's Bay specimen are shown in Fig. 1.
The significance of the structure is not known, but it appears to be an interesting mutant. Professor R. B. Goldschmidt, Professor of Genetics, University of California, considered that the Brown's Bay wing is comparable to the homoeotic mutant podoptera of Drosophila melanogaster (Goldschmidt, 1945), but stressed that this could be proved only by a breeding test (in litt.). Although a search was made in the same area, further specimens were not found. It is probable that this mutant is very rare and further specimens might be obtained only if a controlled breeding programme from stock from the Brown's Bay population was carried out.
The fly is in the Diptera collection and the right wing in the microscope slide collection of the Plant Diseases Division, Department of Scientific and Industrial Research, Auckland, New Zealand.
Goldschmidt, R. B., 1945. The Structure of Podoptera, a Homoeotic Mutant of Drosophila melanogaster. J. Morph., v. 77, no. 1, July, 1945, pp. 71–103.
Tonnoir, A. L., and Malloch, 1926. New Zealand Muscidae Acalyptratae. Part I, Ephydridae. Rec. Cant. Mus., vol. 3, no. 1, pp. 1–8.
[Footnote] * Identified by the Commonwealth Institute of Entomology.