Drosophila moli Magnacca

Magnacca, Karl N. & Price, Donald K., 2012, New species of Hawaiian picture wing Drosophila (Diptera: Drosophilidae), with a key to species, Zootaxa 3188, pp. 1-30 : 18

Drosophila moli Magnacca , new species

Fig. 4

Diagnosis. The wing and body coloration patterns resemble others in this species complex, including D. lanaiensis , with which it was formerly grouped, and females of D. conspicua . Males can be immediately distinguished by the elongate, narrow wings, and both sexes have the mark over the dm-cu crossvein distinctly L-shaped.

Description. Male. Head. Front pale, faintly tinged with brown; ocellar triangle black. Fronto-orbital setae normal, anterior reclinate very small, about half as long as the proclinate and one-third as long as the posterior reclinate. Face and gena pale yellow except for a small black spot below the eye. Antenna with the second segment brown laterally, otherwise yellow; arista with about 9–10 dorsal and 4 ventral rays in addition to the apical fork, and several rather long median branches. One strong oral vibrissa, followed posteriorly by three progressively smaller setae, with numerous small setulae in between them. Palp largely yellow, slightly darker at the tip, nearly cylindrical; with a long, thin, yellow apical seta. Thorax. Mesonotum largely yellow with three strongly contrasting dark brown to black stripes; lateral stripes dark, extending from the anterior margin of the humeri nearly to the scutellum; median stripe fainter, broadening between the dorsocentral setae to fill the space between them, and extending onto the scutellum. Pleura almost entirely yellow except for a large dark mark on the posterior half of the anepisternum. Two pairs of strong dorsocentral setae, the anterior about 2/3 as long as the posterior. Legs. Entirely yellow. Front tibia with regular anterodorsal and posterodorsal rows of 10–12 long cilia along its entire length, slightly longer at the base, with a few scattered dorsal cilia in between. Front tarsus with about 20 dorsal cilia arranged in three irregular rows, similar to those of the tibia. Second and third tarsal segments also with sparse cilia. Wings. Extremely long and narrow, about four times as long as wide; apically pointed and slightly bent posteriorly, posterior margin between M and CuA1 weakly concave. Subbasal wing spot small, scarcely reaching into cell R2. Anterior mark elongate, extending along about 1/3 the length of the wing; connected to the large L-shaped mark on the dm-cu crossvein via a small circular mark over R2+3 (the latter rarely reduced or absent). Apical marks confluent or nearly so. Costal fringe extending about 1/2 the distance between apex of R2+3 and R4+5. Abdomen. Coloration variable, from each segment predominantly yellow with only a narrow posterior band dark brown, to predominantly brown with yellow anterolateral areas. Cerci yellow-brown. Genitalia not dissected.

Female. Identical to the male with the following exceptions. Head. Third antennal segment tinged with brown. Apical seta of palp shorter, stronger, black. Thorax. Median stripe of mesonotum broader on the anterior half and dark, similar to the lateral stripes. Legs. Front legs without elongate cilia or setae. Wings. Not as long and narrow, about three times as long as wide; shape normal, posterior margin convex, apex only very weakly pointed. Abdomen. Ovipositor long, straight, yellow, pointed vertically at rest.

Types. O‘ahu: Holotype 3 and allotype Ƥ, above Nu‘uanu Pali lookout, 1400 ft., 21.365°N 157.761°W, on bait sponge, 2.viii.2009, K. Magnacca (UHIM); paratype, 3, same data (BPBM).

Distribution and ecology. O‘ahu. Probably breeds in Charpentiera ; females observed ovipositing in rotting trunk (not reared).

Etymology. From the Hawaiian m ō l ī, albatross, referring to the similarly long, narrow, pointed wings.

Discussion. Hardy (1965) considered this population from O‘ahu to be conspecific with D. lanaiensis , described from only females. However, it is now clear that the D. lanaiensis types are identical to recent specimens from Lāna‘i and those from Maui (previously known as D. virgulata ), and different from the O‘ahu specimens (see Discussion under D. lanaiensis above). The drawing of the male wing in Hardy (1965) appears to be of an unusual specimen; all those I have seen possess a small but distinct spot in the middle of vein R4+5, as in D. lanaiensis and D. digressa , although it is missing on one wing of the D. moli allotype. This variation is occasionally seen in individuals of the other two species as well. None of the specimens examined by Hardy, or any other earlier ones, could be located in the BPBM or UHIM collections. Although it has not been reared from Charpentiera , it was observed ovipositing in a rotting tree, and D. digressa and D. lanaiensis have both been reared from it. This species is probably highly vulnerable due to habitat loss; although Charpentiera is still relatively common on O‘ahu, the restricted range suggests that D. moli requires large trees to breed in, and these are increasingly scarce. In recent years it has only been taken at the type locality. It has been reported from Hālawa Valley (S.L. Montgomery, pers. comm.), but the specimens could not be located. Other potential sites may exist in the middle and northern Ko‘olau range, but are difficult to access.

Figures

FIGURE 4. Drosophila moli. A. Right front leg of male, anterior view. B. Male wing. C. Female wing.