Drosophila oreas Hardy, 1965

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 : 22-24

Drosophila oreas Hardy, 1965

Fig. 7

Drosophila oreas Hardy, 1965:399 . Type Ƥ, Haleakalā, 1,500 ft., no collector or date, BPBM 6415.

Diagnosis. The wing markings, with a quadrate anterior mark spanning R2+3 and R4+5 beyond the dm-cu crossvein, are distinctive enough to separate this species from all others. The male has not been previously described; the setation of the front legs is very similar to D. macrothrix of Hawai‘i, to which it is most closely related.

Description. Male. Head. Front pale brown; area between ocelli slightly darker, remainder of ocellar triangle concolorous with front. Fronto-orbital setae normal, anterior reclinate 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 and third segments brown; arista with about 8–9 dorsal and 2 ventral rays in addition to the apical fork, and several median branches. One strong oral vibrissa, followed posteriorly by a row of smaller setae. Palp pale brown, elongate, narrow, slightly broadened near the middle; with a very long, thin, yellow-brown apical seta, curled at the apex, about 1.5 times as long as palp. Mentum brown. 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 filling in most of the space between the acrostichal setulae, narrowing abruptly at posterior margin. Scutellum almost entirely dark brown to black except at lateral margins.

Pleura predominantly yellow, with a narrow dark stripe along the dorsal margin of the anepisternum; an irregular round mark on the anepimeron below the wing base; and the posterodorsal third of the katepisternum dark. Two pairs of strong dorsocentral setae, the anterior about 2/3 as long as the posterior. Legs. Almost entirely yellow, marked with brown on mid and hind coxae, all trochanters, and with faint tinges of brown at apices of femora and both ends of hind tibiae. Front tibia with an anterodorsal row of about 15 long curved cilia each along its entire length, slightly longer at the base, and a transverse row of 3 apical dorsal cilia; dorsal surface otherwise completely bare, lacking small setulae. Front basitarsus with a row of 7 anterodorsal cilia along the entire length, 3 posterodorsal cilia over the apical third, and a dorsal cilia at the apex. Second and third tarsal segments each with a single dorsal cilia. Wings. Shape normal, about three times as long as wide, rounded at apex. Subbasal wing spot large, extending posteriorly into cell M, covering r-m crossvein, and with an anterior prolongation in cell R1. Anterior median mark quadrate, extending from costal margin posteriorly beyond R4+5. Apical marks discrete; mark at apex of R4+5 small and nearly circular, mark on M elongate, reaching nearly halfway to dm-cu crossvein. Mark on dm-cu crossvein large and quadrate, extended distally on CuA1. Costal fringe extending about 1/2 the distance between apex of R2+3 and R4+5. Abdomen. Each segment yellow on anterior half, brown posteriorly and medially. Cerci brown, quadrate, about as long as high. Parameres of aedegus each with a very short, yellow apical setula. Preapical protuberance of aedeagus very strong, vertical on apical side.

Female. Identical to the male with the following exceptions. Head. Apical seta of palp shorter, stronger, black. Legs. Front legs without elongate cilia or setae. Abdomen. Ovipositor long, straight, brown, pointed vertically at rest.

Material examined. Maui: 13 1Ƥ, Pua‘aka‘a Stream, 1300 ft., 18.xii.2010, K. Magnacca. 23 4Ƥ, Waikapū Valley, 2000 ft., 15.x.2011, K. Magnacca.

Distribution and ecology. Maui; very rare. Breeds in Pisonia umbellifera (pāpala kēpau, Nyctaginaceae ) ( Montgomery, 1975).

Discussion. Nearly all specimens of this rare species previously came from a single site on East Maui, at Pua‘aka‘a. It had been collected only once on West Maui, at Pohakea Gulch, and no suitable habitat was found on a recent visit there. However, a sizable population was recently found in nearby Waikapū Valley, and other undiscovered sites may yet exist on both sides of the island. Its sister species, D. macrothrix , is likewise currently restricted to a single site on Hawai‘i, though it was formerly more widespread. Together they are probably related to D. spaniothrix , which is only known from a few collections on O‘ahu and has not been collected since 1971. At least D. oreas and D. macrothrix breed in Pisonia , but they may occupy a unique niche as the host is much more widespread than any of the species.

Figures

FIGURE 7. Drosophila oreas. A. Right front leg of male, anteroventral view. B. Wing. C. Male terminalia, lateral view. D. Left palp of male, dorsal view.