Xenasteia fijiana, Grimaldi, 2009

Grimaldi, David A., 2009, The Asteioinea of Fiji (Insecta: Diptera: Periscelididae, Asteiidae, Xenasteiidae), American Museum Novitates 3671, pp. 1-60 : 51-56

Xenasteia fijiana , new species

Figures 24 , 30 , 31

DIAGNOSIS: Body largely dark brown with metallic highlights; legs light yellowish; scutellum velvety black; anteriormost (inclinate) fronto-orbital seta very small, about one-third the size of adjacent FO seta; wing with br-m cross vein almost completely lost. Distinguished from the very similar species X. divergens and X. similis by male terminalia, which in X. fijiana have stouter cerci, thicker surstyli, more slender posterior lobes of the hypandrium, thicker paraphyses, and a hypandrium and epandrium that is broader.

DESCRIPTION: ThL 5 0.58 mm. Body coloration: Frons, scutum, pleura, abdominal tergites glossy, polished brown. Eyes light pink, ocelli light yellowish. Antennal pedicel and basal flagellomere yellowish. Arista light brown, base whitish. Face, palps, proboscis very light yellow. Scutellum velvety blackbrown. Dorsal portion of pleura slightly darker than ventral portion. Femora very light brown, tibiae and tarsi light yellow. Wings hyaline, no patterning. Halter light brown, particularly knob. All setae blackish brown; lighter on legs and ventral portion of thorax.

Head: Broad, width slightly greater than that of scutum; postocciput deeply concave, anterior surface of scutum adpressed deeply into postocciput, such that posterior margins of eyes nearly reach to notopleural setae. Eyes bare of interfacetal setulae; no differentiation of facets; eye oblong in frontal view. Frons with lateral margins significantly convergent anteriad, width of anterior margin ca. 0.5X width of posterior margin of frons. Polished surface of ocellar triangle demarcated by thin, finely striate frontal vittae. Pair of strong ocellar setae present, about equal in size to anterior fronto-orbital; postocellars 0.7X size of ocellars, convergent to slightly cruciate. Inner verticals (upright, parallel) and outer verticals (lateroclinate) longest setae on head, approximately in size. Fronto-orbital plates with 2 large pairs setae posteriad, 3 small pairs anteriad (lengths ca. 0.4X that of PFOs); large setae lateroclinate to reclinate, small pairs inclinate. Antenna with pedicel having thick, upright seta on dorsal surface; pedicel with deep dorsal cleft, posterolateral surface short- er than anteromesal surface. Basal flagellomeres with fine setulae, flagellomeres only slightly divergent; arista completely bare (no evidence of fine hairs), base swollen about twice thickness of trunk. Face narrow, recessed, lightly sclerotized (possibly membranous); cheeks very shallow, depth equal to diameter of one eye facet. One pair of welldeveloped vibrissae, with 4–5 smaller setae posteriad. Clypeus very narrow. Palps slightly curved, with ventral row of fine setulae.

Thorax: Scutum only slightly arched, with two pairs dorsocentral setae that are closely situated (separated only one-half length of anterior DC). Acrostichal setulae numerous, scattered (barely in rows) over anterior half of scutum; acrostichals larger, about one-half the size of anterior dorsocentrals. Anterior DC about 0.6X length of posterior DC. Scutellum with two pairs of setae, anterior pair 0.6X length of posterior (apical) pair. Lateral setae of scutum: one supraalar, one presutural, two notopleurals, one postpronotal. Katepisternum with two setae near dorsal margin, anterior seta 0.5X size of other. Legs: forefemur with ventral row longer setae; midtibia with long apical spur (length ca. 2X thickness of tibial apex); basitarsomeres with ventral ‘‘combs’’ of thick setulae; claws large, black; pulvilli whitish, feathery. Wing: Hyaline; vein C extended to apex of R 4+5; no break in C at cross vein h, break near where R 1 joins C. R 2+3 short, length 0.65X that of R 4+5. Slight vestige of cross vein r-m present, cross vein largely lost and extremely short; vein M beyond this point is evanescent, represented by row of microtrichia. Vein CuA 1 straight, apex incomplete. Vein CuP or A largely or completely lost, alula present but narrow, with marginal fringe. Anal lobe present, with denser microtrichia on membrane surface.

Abdomen: Rotund, with tergites large and well sclerotized, with very fine setulae; sternites short, lightly sclerotized. Male terminalia: Tergite VII small, connected via narrow strips to ventrolateral lobes (‘‘sternites VIII, VII, VI’’) according to Hardy (1980). Epandrium short, with setae and microtrichia on dorsal surface. Cerci large, setose; surstyli long, slender lobes that project ventrad, apices with slight scales on inner surfaces. Hypandrium roughly triangular in shape, articulating laterally with epandrium, having long, projecting posterior lobes; each hypandrial lobe with two subapical spines pointed laterad. Aedeagus small, membranous lobe at base of paraphyses and posterior lobes of hypandrium. Aedeagal apodeme long.

TYPES: Holotype, male (dissected). Fiji : Viti Levu Isl., Sigatoka Prov., Sigatoka Sand Dunes N. P., Malaise [trap] 22.XII.02–3.I.03 FJ6B, 44 m, M. Irwin, E. Schlinger, M. Tokota’a 177 ° 2899100E 18 ° 999990S FBA045434 . Paratypes: female, same data as holotype, except FBA- 045434. Other paratype same locality except: 1.1 km SSW of Volivoli, 50 m, 23.IX–8.X.02, Schlinger and Tokota’a, FJVL6 b_M03_01, 218.1694, 177.4847 FBA059114 (females not dissected) .

ETYMOLOGY: In reference to Fiji.

TABLE 2 Species and specimen numbers of Asteiidae and Periscelididae on major Fiji islands (Mt 5 Malaise trap; Asp 5 aspirated from rolled leaves)

COMMENTS: Specimens of what appear to be X. divergens Hardy were dissected for comparison. These specimens, housed in the NMNH, are from Palau, Koror Island, coll. IV.17.57 by C.W. Sabrosky ( divergens occurs in Palau). Xenasteia fijiana appears to be most closely related to X. similis Hardy and X. divergens based on several features of male terminalia: apex of surstylus is textured (with slight, microscopic scales on mesal surface), anterolateral margins of hypandrium are concave, and the aedeagus is relatively short. Moreover, X. divergens (but also X. sabroskyi Hardy and X. shalam Freidberg ) have a velvety, black scutellum—a distinctive feature that unfortunately is rarely mentioned in most of the descriptions.

Figures

Fig. 24. Wings (entire and detail of bases) of Fiji Asteiidae and Xenasteiidae. A, B. Asteia pleurovitta, n. sp. C, D. Asteia vitiensis, n. sp. E, F. Xenasteia fijiana, n. sp. A, C, E to same scale; B, D, F to same scale.

Fig. 30. Xenasteia spp. A. Oblique frontal view of frons in Xenasteia divergens Hardy. B. Oblique frontal view of head of Xenasteia fijiana. C. Left lateral habitus of Xenasteia fijiana. All to the same scale.

Fig. 31. Male terminalia of Xenasteia spp. A–C: Xenasteia divergens. A. Segmentation in posterior view (diagrammatic), comparing homologies with Hardy (1980) and as used here. B, C: Entire genital capsule in oblique lateral view. C. Entire genital capsule in ventral view. D, E: Asteia fijiana. D. Entire genital capsule in oblique lateral view. E. Entire genital capsule in ventral view. B–E to same scale.