Wing measures of 97 species of Drosophilidae (Diptera) photographed by Duda in 1924

The taxonomy of the Drosophilidae of New Guinea requires detailed knowledge of the fauna of neighbouring regions to the south (Australia), the east (islands of the South Pacific), the west (Indonesia) and the northwest (Philippines). The majority of species known from Indonesia were collected on Java and Sumatra by Jacobson in the period 1906–1929; he deposited all his specimens in Dutch museums and they are now at Naturalis in Leiden. De Meijere and Duda worked independently on this material in the first decades of the twentieth century and between them described most of it. Since then very little taxonomic research has focused on the drosophilid fauna of this part of the world. Duda (1924) published photographs of the wings of 103 fly species including 48 drosophilids from Southeast Asia (mainly Java and Sumatra). The venation, visible in each photo, has now been measured and tabulated here (Table 1). It is known that wing venation is variable between, but not significantly within, species and therefore provides a useful diagnostic tool. Diagnostic success is greatly enhanced when comparative analysis involves many metrics screened simultaneously. About seven standard wing indexes that describe ratios of vein lengths and sections (e.g., C, 4v, 4c, M, 5x, hb, prox.x, etc., see Table 2) are available for almost all drosophilids described since the 1950s. Standard measure-points or landmarks of the drosophilid wing are given by McEvey (2017). Datasets of wing indexes can be assembled from the literature. It is possible to interrogate such datasets with the measurements of an unknown taxon to produce a shortlist of one or several taxa that are possibly conspecific. The tables presented here list the wing indexes of all 103 species pictured by Duda (1924), many of them are given here for the first time. These metrics can be appended to available datasets greatly facilitating research on the largely undescribed drosophilid fauna of New Guinea.Table 1. Wing measures based on 104 fly wing photos published by Duda (1924, Arch. Naturgesch. 90(A3): 172–234). Heavy setation in the third costal section is not visible and could not be measured; in several instances dark wings obscured venation; Duda’s original 1924 figure captions are given as well as the currently valid name (Taxon); all photos are at the same scale (Vergrößerung einheitlich), wing length (WL) in the D. melanogaster photo (Fig. 82) is, from other data, 1.63 mm and so magnification factor is 18 not 11 as stated by Duda. SEA = present in southeast Asia; * see Brake & Bächli (2008, Drosophilidae (Diptera). World Catalogue of Insects).Table 2. Key to abbreviations for wing measures and indexes used in Table 1; a vein or vein-section length is the distance between two measure-points or landmarks (see labelled diagrams of measure-points in McEvey, 2017).