Stenocyamops robustus, Grimaldi, 2009

Grimaldi, David A., 2009, The Asteioinea of Fiji (Insecta: Diptera: Periscelididae, Asteiidae, Xenasteiidae), American Museum Novitates 3671, pp. 1-60 : 33-37

Stenocyamops robustus , new species

Figures 2 , 3 , 4 , 16 , 17 , 20 , 21

DIAGNOSIS: Large-bodied species (0.74 mm ThL), with pleura, ventral portion of thorax, and femora black-brown; scutum ochre with broad, longitudinal, black-brown vitta, female tergites III, IV, VI and all male tergites blackbrown (others yellowish). Male genitalia with long, pointed, sclerotized ventral lobes of cerci; surstylus scimitar shaped, apically bare; hypandrium with pair of broad, flat phragmata having continuous margins.

DESCRIPTION: ThL 5 0.74 mm. Body coloration: Head: Frons and face ochre; vertex, ocellar triangle, oral margin, and clypeus light brown; postgena light yellow; eyes brick red; ground color of cheeks light brown, overlain with silvery-reflective microtomentum. Antennal pedicel dorsally brown, ventrally ochre; basal flagellomere ochre; arista blackish brown. Thorax: Dorsal portion of scutum and scutellum dark brown, graded to ochre in notopleural areas of males, in females dark brown area with more discrete lateral edges and bounded by dorsocentral setae; pleura mostly dark brown, including ground color of anepisternum; anepisternum largely covered with silvery-reflective microtomentum; halter base dark brown, bulb white. Legs with coxae, femora, tibiae mostly dark brown, apices and trochanters lighter; foretarsi light yellow, mid- and hind tarsi whitish. Wing: very slightly and evenly infuscate, with a barely perceptible light transverse band just apical to cross vein dm-cu (best viewed at oblique angle with dark background, better developed in females). Abdomen of male with tergites and sternites entirely blackish brown; female with tergites I, II, V, and anterolateral corners of tVI yellow. All setae on body blackish brown.

Head: Two pairs of frontal-orbital setae present, anterior pair proclinate, slightly shorter than posterior FOs (which are erect); bases of ipsilateral anterior and posterior Fos separated by approximately the diameter of base socket. Ocellar setae and setulae absent; lateral ocelli either diminutive or same size as anterior (median) ocellus. Inner vertical setae proclinate, slightly divergent; outer vertical setae erect, divergent; lengths of each approximately equal. Eyes emarginate surrounding bases of antennae and on posterior margin bordering postgena; eyes with sparse, fine interfacetal setulae; fronto-median facets smallest in males, largest facets (ca. 1.5X diameter of smallest ones) dorsally and ventrally (females with less differentiation). Pedicels laterally flattened, with larger mesal surfaces, inner margins touching but pedicels divergent, having stout seta each on anterior surface that is projected forward and upward, with dorsal seam; basal flagellomeres divergent, each with minute tuft of setulae at apex and pair of small, stiff setae on ventromesal margin. Arista with 6–7 dorsal and 2 ventral branches (plus terminal fork); basal 4–5 dorsal branches crowded near base of aristal trunk, branches projecting laterad. Ptilinal suture extended to approximately level of pseudovibrissae, slightly convergent ventrad. Face protrudent, slightly recessed below level of pseudovibrissae. Pseudovibrissae stout, projecting forward and slightly divergent; bases separated by distance approximately equal to diameter of base socket. Ventral to pseudovibrissae are 6 pairs oral setae; 2 pairs closest to pseudovibrissae project forward and curve slightly laterad; others project laterad and curve slightly ventrad. Clypeus small; oral cavity large, with proboscis generally entirely retracted within.

Thorax: Deep; depth approximately equal to length in lateral view. (Meso-) scutum with single row of 6–8 long acrostichals, extended posteriad to level of dorsocentrals; dorsocentrals in graded series of 6–8 setae, with long posterior dorsocentral (longest seta on the fly), anterior to it one that is half the length, and anterior to that a smaller one, etc. Mesoscutellum with single pair of long setae, virtually erect. Postpronotal lobe with one or two very fine, short setae; notopleuron with two setae, and one finer seta above and between the notopleurals. (A supraalar seta present only in one specimen: no. 28.) Anepisternum with row of 5–6 fine setae on posterior margin. Single, erect, slender setae on dorsal portion of katepisternum. Coxae, mesosternum, and katepisternum with dense pilosity of long, fine setae. Forecoxa slightly flattened, with posterior surface adpressed to thorax, distal articulation facing laterad, with trochanter and femur projecting laterad. Basisternum triangular, lying between forecoxae; mesosternum broad; midcoxa narrow, anteriorly transverse and largely fused to posterior margin of mesosternum, posteriorly reduced to a narrow sclerotized strip in membrane, trochanteral articulation at posteromesal corner of coxa. Hind coxa with similar structure, but largely free (i.e., an anterior articulation to thorax), lying immediately posterior to mid coxa. Forefemur with long, fine, erect setae, pair of thick setae on distolateral surface, plus long, fine seta basally. Midtibia with long, stout, apical spur, length about half that of basitarsomere. Hind tarsi slightly flattened, white, with inner edge having feathery seam of golden, transverse rows/combs of setulae.

Wing: Fairly broad (W/L 5 0.43). Membrane with dense, well-developed microtrichia on dorsal and ventral surfaces, microtrichia arranged approximately in rows on distal half. Veins dark, sclerotized. Costal vein terminates at apex of M 1+2, with two longitudinal rows of long setulae, long dorsal seta at base; row of 2–4 long, stout setae proximal to where R 1 meets C. No break in C near cross vein h; C weakened but no gap where Sc meets C. Vein Sc incomplete, with terminal end abrupt, not tapered. Dorsal surface of vein R1 with row of 0–5 fine setae. Vein R 2+3 relatively straight; vein R 4+5 ends at apex of wing; vein M 1 slightly convergent with R 4+5. Cross vein r-m with m end reduced. Cross vein bm-cu and vein CuA 2 lost; cross veins not close together (L r-m / distance between r-m and m-cu 5 0.19), vein A 1 +CuA 2 present, short, with abrupt (vs. tapered) terminal end. Vein A 1 absent. Alula reduced, anal lobe present (anal margin not parallel with CuA 1).

Male Terminalia: Paired structures and hypandrium symmetrical. Epandrium setose, deep, with shallow dorsal bridge. Dorsal portions of lobes of cerci fused, membranous; ventral lobes of cerci long, pendulous, setulose, apically pointed, apex extended to nearly ventral margin of epandrium. Surstylus scimitar shaped (slightly curved, apically pointed), basal half setulose, no teeth or setae on mesal margin, no setulae at apex. Hypandrium reduced to lateral lobes bearing round, flat phragmata, with small median gap where lateral lobes nearly join. Aedeagus short, bulbous, spiculed, as figured. Female Terminalia: With tVI a simple dorsal plate (not fused to sternite), bearing pair of spiracles at lateral margins; sternite VII and tergite VII fused into a ring, bearing pair of spiracles laterally; tergite VIII a short, narrow sclerite, without spiracles; two spermathecae, heavily sclerotized, spherical.

TYPES: Holotype, male, FIJI: Viti Levu , VII.9.08, Nakobalevu Rd., 394 m., 18 ° 039310S, 178 ° 249550E, in rolled leaves, D. Grimaldi. Not dissected or numbered . Paratypes: Female , same data as holotype (no. 31); male, Viti Levu : VII.11.08, Namosi Rd, 200 m, 18069110S, 178109290E, in rolled banana leaves, D. Grimaldi (dissected, no. 28); female, Vanua Levu: VII.7.08, road up Mt. Ndulaikaro, 1000 m, in rolled leaves wild ginger, D. Grimaldi (no. 32, not dissected) .

ETYMOLOGY: From the Latin, robusta , for ‘‘large,’’ in reference to the large body size.

COMMENTS: Variation is substantial but difficult to assess with only four specimens. The minute size of the lateral ocelli in the male holotype is interpreted as a teratology, since there seems to otherwise be little difference between it and the other specimens from Viti Levu. The female from Vanua Levu differs the most: the face is slightly more protruding, the silvery microtomentum on the cheeks slightly more extensive, and the anterior dorsocentrals longer than in the other specimens .

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. 16. Heads of Fiji Stenocyamops, oblique frontal views. A. S. robustus (spcm. 28). B. S. luteus (spcm. 29). To same scale. Differentiation in facet size is modest, and silvery microtomentum is restricted to the cheeks.

Fig. 17. Wings of Fiji Periscelididae. A–C: Stenocyamops. A, B. S. luteus, entire (B) and detail of base

Fig. 20. Male terminalia of Stenocyamops robustus (spcm. 28). A. Epandrial complex, posterior view. B. Aedeagus, hypandrium, aedeagal apodeme, anterior view. To the same scale.

Fig. 21. Female terminalia of Fiji Stenocyamops, dorsal views (all to the same scale). A. S. luteus (spcm. 34). B. S. vittatus (spcm. 33). C. S. robustus (spcm. 31). Spermathecae are heavily sclerotized; the last pair of spiracles occur in the lateral margins of syntergosternite VII.