Stenomicra distincta, Grimaldi, 2009

Grimaldi, David A., 2009, The Asteioinea of Fiji (Insecta: Diptera: Periscelididae, Asteiidae, Xenasteiidae), American Museum Novitates 3671, pp. 1-60 : 17-22

Stenomicra distincta , new species

Figures 2–5 , 12

DIAGNOSIS: Distinctive species with bold, contrasting blackish-brown and light yellow markings: ocellar triangle, scutum, scutellum, postnotum, anepisternum, tIV+V (males; in females also tVIII+IX) dark blackish brown, rest of body light yellowish. Wing entirely hyaline. Cerci with two pairs of large, stiff setae ventrally; distiphallus long, slender.

DESCRIPTION: ThL 5 0.53 mm. Body coloration: Frons, face, cheeks, postgenae, proboscis very light yellow, only dark area of head is blackish ocellar triangle. Eyes light purple. Scape and pedicel light orange; arista coppery brown. Scutum, scutellum, postnotum, most of anepisternum and anterior portion of anepimeron blackish brown; rest of thorax whitish to yellow. Mesosternum yellow. Legs with diffuse yellow on femora, other podomeres whitish. Wing completely hyaline; halter white. Abdominal tergites mostly light to dark yellow, except tIV, V, VIII (epandrium) in males dark brown; these three tergites plus IX dark brown in females. Setae on frons mostly light yellow; pseudovibrissae, oral setae, and mesonotal setae brown. Setae and setulae on legs and ventral surface of thorax very light yellow.

Head: Chaetotaxy and other features similar to that of Stenomicra tokotaai , with exceptions as follows: Vertical setae shorter; arista with four dorsal and two ventral branches. Pseudovibrissae on facial protuberance projecting forward and curved upward; bases separated by distance approximately 2X diameter of basal sockets. Oral margin ventral to pseudovibrissa with row of four setae, projecting laterad and curved slightly downward.

Thorax: Scutum with single, incomplete row of 6–7 long, fine acrostichals; two pairs larger dorsocentral setae (finer setulae anterior to these), anterior dc ca. 0.7X length of posterior dc. Katepisternum with one long seta near dorsal margin. Wing hyaline, fairly broad (W/ L 5 0.23); cross veins not particularly close (L r-m / distance from r-m to m-cu 5 0.23); wing tip rounded, alula virtually lost, vein A 1 +CuA 2 reduced to short spur but present. Abdominal tergite VI of male approx. equal to length of tVII; abdominal apex of female less tapered. Male genitalia: Epandrium deep, setose, with ventromedial notch for cerci; cerci lightly sclerotized on ventral portion only (dorsal portion membranous), with 7 spiculelike setae on each lobe, ventral margin with 2 long, stiff setae pointed ventrad. Surstylus simple, with blunt, sclerotized apex; slender, length ca. 4X greatest width. Hypandrium slightly asymmetrical, with right side slightly larger. Aedeagus typically complex, with right, spiculed, membranous lobe to which is connected a sclerotized strip; a median, membranous lobe with scales; ventral lobe (distiphallus) that is slender, pointed, spicules at apex. Left paraphysis (?) present, slightly sclerotized, as figured.

TYPES: Holotype, male: Fiji: Viti Levu , VII.10.08, Savura Topline Rd, 150 m, in rolled leaves of wild ginger, D. Grimaldi (no. 36: not dissected).InAMNH . Paratypes: 1female (no. 37) same data as holotype. 1 male: Viti Levu , VII.11.08, 18 ° 029150S, 178 ° 109030E, in rolled banana leaf, 100 m, D. Grimaldi coll. (no. 38: dissected) .

ETYMOLOGY: Fom the Latin distincta (fem., ‘‘different, separate’’), for the distinct coloration.

Stenomicra distinctipennis (Collin) , new combination

Figures 1 , 4 , 5 , 13

Diadelops distinctipennis Collin, 1951: 41 .

Stenomicra fascipennis Malloch, 1927 : Sabrosky, 1965 (as probable synonym).

DIAGNOSIS: Easily distinguished from oth- er species of periscelidids in Fiji by the slender, gray body; infuscate wing with whitish bands over the cross veins and at base, and the setae on the head (inner verticals minute, anterior fronto-orbitals nearly lateral to posterior FOs). Distinguished best from other species in the S. fascipennis species complex (see below) by the distinctive shape of the surstylus, which are strongly curved and have a setose lobe at base of inner margin.

DESCRIPTION: Body coloration: Frons, face, cheeks pollinose and yellowish, ocellar triangle brown; scape, pedicel, and basal flagellomere ochre. Eyes light pink. Scutum and scutellum brown with a layer of light bluish pollinosity; pollinosity heaviest as two paramedian vittae (specimen requires tilting under light for best observation). Dorsal portion of pleura (anepisternum, anepimeron) brown, remainder of pleura and most of legs light yellow (tarsomere 1 light brown). Abdominal tergites uniformly brown, including all of syntergosternite VII, tergites slightly lighter anteriad. Halter knob light brown. Wing with infuscation pattern as described below. Arista and dorsal setae of body coppery, setae on light cuticle (legs, pleura) are blond.

Head: greatest length in profile is oblique. Frons flat. Two pairs fronto-orbital setae present, setae long and fine: reclinates slightly posteromedial to proclinates, approximately equal in length. Fronto-orbitals lie near middle of frons at margin of eyes. Inner vertical setae minute, posterior to ocellar triangle; outer vertical setae large, divergent, slightly shorter than fronto-orbitals. Eye is an irregular oblong in lateral view; posterior margin flat to slightly concave, anterior margin convex. Eye with dense but short, fine interfacetal setulae. Cheek deep, greatest depth ca. 0.5X greatest depth of eye. Face with protuberance in middle, ventral portion of face sloping posteroventrad. Pair of large, divergent, upturned pseudovibrissae at apex of protuberance; two pairs downturned setae ventral to pseudovibrissae, lengths approximately equal to pseudovibrissae. Maxillary palps reduced to minute papillae; labellum broad, in well-preserved specimens where labella fully unfolded, lateral margins of labella with dense fringe of fine lobes (pseudotracheal extensions?). Antenna with pedicel caplike, having inner surface ca. 2Xlength of lateral surface; pedicel with single dorsal seta and with dorsolateral seam. Basal flagellomeres divergent, each with minute tuft of setulae at apex. Arista with long branches: 4 dorsal, 2 ventral (besides terminal fork).

Thorax: Scutum flat, not domed or significantly convex; with short, single row 4–5 acrostichal setulae; two larger pairs dorsocentrals, posteriormost pair long and fine; dorsocentrals decreased in size anteriad. Scutellum with single pair long (apical) setae. Thorax with 2 notopleural setae; 1 long, erect katepisternal; no postpronotals. Wing with infuscation pattern: along middle of wing with infuscation, interrupted by incomplete whitish bands over cross veins dm-cu and r-m, and at base; slight whitish area preapically over tip of R 2+3. Cross veins dm-cu and r-m at nearly right angle to longitudinal veins; distance between these cross veins 2.3X length of cross vein dm-cu. Greatest width of wing 0.37 the length (from wing tip to level of cross vein h).

Abdomen: Epandrium hemispherical, with short, stiff setae over much of surface; inner lateral walls with pair of sclerites (tergal remnants?), to which articulate dorsal arms of hypandrium. Dorsal portion of cerci membranous, with lightly sclerotized ventral, pendulous lobes; ventral tips of cerci with 2–3 long, fine setae. Sursylus distinctive: strongly curved, crescent shaped, apex lightly sclerotized, scooped shaped, apical margin concave; base of surstylus with large lobe on mesal surface, having 3 fine setae on apex of lobe. Hypandrium divided, asymmetrical (as figured), apex of arms articulate dorsally with condyle on inner wall of epandrium and with ‘‘tergal remnants.’’ Aedeagal apodeme reduced to paddlelike structure. Aedeagus bulbous, surface extensively spiculed, without sclerotized band/strip at apex; apex turned to right.

TYPES: Not specified by Collin (1951), material mentioned: Fiji : Viti Levu, Wainibokasi, 29.iii.49, B.A. O’Connor, on para grass (1 male); Viti Levu, Naduruloulou, viii.50, B.A. O’Connor, on para grass (7 males, 5 females). In NHM, London .

MATERIAL EXAMINED: FIJI: Viti Levu: Serua Prov., Nambukelevu, 1.XII.85, W.W. Wirth (1, NMNH); Nandi, 0–100 m, 5. III.74, N.L.H. Krauss (6, NMNH; 1 male dissected [no. 26]); Naitairi Prov., Etnei, Novai, Malaise trap, 6. VI –15. VII.2003, FJ11B, 700 m, M. Irwin, E. Schlinger, M. Tokota’a, 177 ° 599E, 17 ° 379S, 1200 m (2 BPBM, 1 AMNH [1 male dissected, no. 25]); Sigatoka Sand Dunes N.P., Malaise 1.1 km SSW of Volivoli. 50 m, 23.IX– 8.X.02, Schlinger, Tokota’a, FJVL 6b_M03_01 (1, AMNH). Viti Levu: Vuda Prov., Koroyanitu EcoPark, Mt. Evans, 1 km E. Abaca, Kokabula Trail : 217.667 °, 177.55 °, 800 m, 12.X– 19.X.2002, Malaise MO1, M. Tokota’a, FBA202858 (male); 17 ° 409S, 177 ° 359E, 19– 26.X.02, Malaise, E. Schlinger and M. Tokota’a, FJVL 02, MO1.64 FBA085404, 085405 (2 males). Naitasiri Prov., 4.8 km N Veisari Stlmt., log rd. to Waivudawa, 300 m, 12.XII.02–3.I.03, Malaise 1, Schlinger and Tokota’a, 18.075 ° S, 178.362 ° E, FBA178233 (1 female). Taveuni: Cakadrove Prov., 5.6 km SE of Tavuki Village, Malaise, rainforest 31.X– 4.XI.02, Schlinger, Tokota’a FJTA 8a_MO1_06, 216.843 °, 2179.965 °, 1187 m, FBA056962 (1 female); Cakadrove Prov., 3.2 km NW Lavena Vlg., Mt. Koronibuabua, 234 m, 24.X.03– 4.I.04, Malaise 2, Schlinger and Tokota’a, 16.855 ° S, 179.891 ° W, FBA169952 (1 female).

COMMENTS: This species belongs to a complex of closely related (cryptic/sibling) species that have traditionally been grouped under S. fascipennis ( Sabrosky, 1965) , known from Madagscar, parts of Africa, Australia, India, and other parts of Southeast Asia to throughout the Pacific from Indonesia to Hawaii and Fiji. The complex was discovered by dissecting the genitalia of males from throughout the putative range of fascipennis (i.e., material reported in Sabrosky, 1965) and comparing these with details of the wings and other features. A separate paper will be published that revises S. ‘‘ fascipennis .’’ The complex is distinguished from other Stenomicra by the presence of a light brown infuscation along the middle of the wing, interrupted by faint, white, transverse bands (one at base, one each over cross veins r-m and dm-cu). The fascipennis complex is also distinguished on the basis of the following combination of external features: anterior (proclinate) fronto-orbital seta large, only slightly smaller than posterior (reclinate) FOS; inner vertical setae proclinate but minute, ca. 0.3X size of outer verticals; scutum brown, with longitudinal strip of bluish pollinosity; pleura with light brown stripe; halter knob light brown; abdominal tergites that are almost entirely brown. Species differ little in chaetotaxy, body proportions and coloration, so it is easy to understand how Sabrosky (1965) did not distinguish the geographic trends in variation. Differences in proportions of wing veins and wing infuscation patterns are subtle but consistent, and the most substantial differences are in the male terminalia. The original description and drawing of the wing by Collin is detailed and very accurate; the terminalia were not illustrated.

Figures

Fig. 2. Thoraces of select Fiji Periscelididae showing coloration, left lateral views (to same scale). A. Stenomicra tokotaai, n. sp. B. Stenomicra distincta, n. sp. C. Stenocyamops robustus, n. sp. D. Cyamops fiji Baptista and Mathis.

Fig. 3. Abdominal coloration of select Fiji Periscelididae, dorsal views (to same scale). A. Stenocyamops vittatus, n. sp. B. Stenocyamops robustus. C. Stenocyamops luteus, n. sp. D, E: Stenomicra tokotaii, male (D) and apex of female abdomen (E). F, G: Stenomicra distincta, male (F) and apex of female abdomen (G).

Fig. 4. A–E: Terminal abdominal segments and syntergosternites of male Periscelididae (ventral views, not to same scale). A. Stenocyamops robustus. B. Stenocyamops luteus/pseudoluteus. C. Stenomicra distincta. D. Stenomicra distinctipennis. E. Stenomicra castanea. F–H: Thoraces (dorsal view) of select Fiji Stenomicra (to the same scale). F. S. brunnea. G. S. xoutha. H. S. sylpha.

Fig. 5. Wings and details thereof of Fiji Stenomicra. A. S. ariela. B, C. S. distincta. D. S. tokotaai. E, F. S. distinctipennis.

Fig. 12. Male terminalia of Stenomicra distincta (spcm. 38). A. Epandrial complex, posterior view. B. Epandrial complex, anterior view. C. Hypandrium, aedeagus, and aedeagal apodeme (anterior view). A and B to same scale.

Fig. 1. Heads of select Fiji Periscelididae, oblique frontal views (not to same scale). A. Stenomicra tokotaai, n. sp. B. Stenomicra distinctipennis Collin. C. Cyamops fiji Baptista and Mathis.

Fig. 13. Male terminalia of Stenomicra distinctipennis (Collin). A. Epandrial complex, posterior view. B. Epandrial complex with genitalia, anterior view. C. Surstylus (terminal view), showing apex in mesal view. D. Genitalia in anterior view (enlarged).