Drosophila atroscutellata Hardy

Lapoint, Richard T., Magnacca, Karl N. & O’Grady, Patrick M., 2009, Review of the spoon tarsus subgroup of Hawaiian Drosophila (Drosophilidae: Diptera), with a description of one new species, Zootaxa 2003, pp. 53-68 : 56

Drosophila atroscutellata Hardy

Figures 2 a and 3a

Drosophila atroscutellata Hardy, 1966: 200

Diagnosis. The spoon structure of Drosophila atroscutellata males is highly reduced relative to the other taxa in this subgroup. The forebasitarsi is slightly extended apically and densely setose with 7 bristles that start at the apex and extend 2/3 of the length of the segment. The second tarsal segment on the forelegs of the male is barely wider than the third tarsal segment, about as long and lacking concavity. Legs mostly yellow, with a dark brown margin at the apical end of the middle tibia (see Fig. 2 a). Thorax light yellow except for the dark brown scutellum. The wings are hyaline except for a dark apical spot extending from the anterior portion of vein R2+3 to halfway through cell M1 (see Fig. 3 a).

Types. KAUA‘I: Holotype ɗ (BPBM 11258), Halemanu Valley, 1220m, 28.viii.1964, HTS. Allotype Ψ (BPBM 11258a), same collection as holotype. Type locality reported as “Malemanu Valley” by Evenhuis (1982).

Material Examined. KAUA‘I: 8 ɗ have been studied from the BPBM: ɗ, Kōke‘e, 3600 ft, vii.1963, HLC, FEC & MRW; 2 ɗ, Kōke‘e, 3600 ft., vi.1964, HLC, FEC & MRW; 2 ɗ, Halemanu Valley, 4000 ft, vi.1964, FEC, MRW, DEH & HTS; 3 ɗ, Nu‘alolo Trail, 3800 ft., v.2007, KNM. Over 40 ɗ and 25 Ψ in the UHIM were also examined from the following localities: 4 ɗ and 4 Ψ, from Kōke‘e, 3600', iii.1964, MRW; ɗ, Kōke‘e, 3600', iv.1964, DEH; 15 ɗ, Kōke‘e, 3600', vi. 1964, DEH, HTS, HLC; ɗ and 2 Ψ, Kōke‘e, 3600', vi.1966, DEH; 4 ɗ, Halemanu Valley, 4000', iii.1964, MRW; 16 ɗ and 14 Ψ, Halemanu Valley, 4000', vi.1964, DEH, HTS, HLC; 3 ɗ and 5 Ψ, Halemanu Valley, 4000', viii.1964, DEH, HTS.

Distribution. This species is endemic to wet forest habitat on Kaua‘i.

Chromosomes. The metaphase complement of this species is 5 rods and 1 dot ( Clayton 1968; Yoon & Richardson 1978).

Illustrations. Foreleg ( Hardy 1966: 201, figs. 3c, d); mouthparts ( Hardy 1966: 201, fig. 3a); wing ( Hardy 1966: 201, fig. 3b); middle tibia ( Hardy 1966: 201, fig. 3e); male genitalia, ventral and lateral ( Hardy 1966: 201, figs. 3f, g); female genitalia, lateral ( Hardy 1966: 201, fig. 3h).

Discussion. Drosophila atroscutellata is the only spoon tarsus species recorded from Kaua‘i. It is considered the most basal member of the group because of its highly reduced spoon.

Figures

FIGURE 2. Fore-legs of selected males a) D. atroscutellata, b) D. dasycnemia, c) D. conformis, d) D. incognita, and e) D. percnosoma.

FIGURE 3. Wings of selected species a) D. atroscutellata, b) D. sordidapex, c) D. conformis, d) D. dasycnemia, and e) D. waddingtoni.