Scelolabes bivittatus Phillipi, 1865

Barros, Luana Machado, Freitas-Silva, Rafael Augusto Pinheiro de & Ale-Rocha, Rosaly, 2023, Revision of Neotropical Scelolabes Philippi (Diptera, Hybotidae, Ocydromiinae): two new species and a proposal of delimitation, European Journal of Taxonomy 890 (1), pp. 49-70 : 57-61

Scelolabes bivittatus Phillipi, 1865

Figs 3–4 , 7B

Scelolabes bivittatus Phillipi, 1865: 751 , pl. 28 fig. 45.

Scelolabes bivittatus – Gerstaecker 1867: 415 (citation). — Bezzi 1905: 458 (catalogue). — Kertész 1909: 104 (catalogue). — Melander 1928: 71 (catalogue). — Collin 1933: 49–51 (redescription). — Smith 1967: 16 (catalogue). — Camousseight 2005: 90 (list). — Yang et al. 2007: 336 (catalogue). — Ale-Rocha & Freitas-Silva 2014a: 441 (citation), 446 (list). — González et al. 2021a: 162 (list), 166 (catalogue).

Diagnosis

Scape and pedicel yellow, postpedicel brown ( Fig. 3D ). Scutum ( Fig. 3F ) orange yellow, except for narrow intra-alar black stripe reaching posterior margin and not extending laterally to notopleural region. Legs ( Fig. 3A ) with long, slender and waved setae, hind femur strongly swollen with 2 rows of spine-like setae, 1 anteroventral and 1 posteroventral.

Material examined

ARGENTINA • 1 ♂; “ Río Negro: Bariloche, Llao-Llao Lane , i.1962, Coscaron, & Capri, 254, Scelolabes bivittatus Phil., N. Papavero det. [19]62”; MNRJ • 1 ♂; “ Chubut: Lago Futalaufquen Lane , i.1962, Coscaron & Capri, Scelolabes bivittatus Phil., N. Papavero det. [19]62”; MNRJ .

CHILE • 1 ♀; “ Chile, E.P. Reed, E.P. Reed Collection”; CAS • 1 ♂, 1 ♀; “[Valparaíso:] Acon. Zapallar , 15.xii.1950, Ross and Michelbacher coll., Scelolabes sp. D . Wilder 1977 det”; CAS • 2 ♀♀; “ Curicó: 3 km SE. of Los Queñes , 1100 m, 9.iv.1966, Mike E. Irwin & Luciano E. Campos coll.”; CAS • 1 ♂; “ Concepcíon: Pinares , 9–13.xi.1970, T. Cekalovic coll.”; MZUSP • 1 ♀; “ Cautín: 20 km E. of Temuco , 1–8–52 [08.i.1952] Ross & Michelbacher leg.”; CAS • 1 ♀; “ Malleco: 18 km W. Angol, Nahuelbuta Ca. Pk [National Park]. 37°48′S, 72°43′W, 620 m, 10.ii.1967, E.I. Schlinger, Scelolabes B.J. Sinclair, 1993 det”; CAS • 1 ♂, 4 ♀♀; “ Osorno: Pq. Nac. [National Park] Puyehue, Termas Aguas Calientes , 40°44′S, 72°19′W, 440 m, 14–31.i.2017, sweeping, V.C. Silva & D.S. Amorim col.”; MNHM • ∙ 2 ♀♀; same collection data as for preceding; MZUSP • 1 ♀; same collection data as for preceding except “ 14.i– 3.ii.2017 ”; MZUSP • 1 ♂, 3 ♀♀; same collection data as for preceding except “ 14.i–3.ii. 2017, 464 m, Shannon trap ”; INPA • 1 ♂; same collection data as for preceding except “ 40°44′09″S, 72°18′19″W, 481 m, pan trap ”; MZUSP • 1 ♀; same collection data as for preceding except “ Sendero Los Rápidos , 40°44′05″S, 72°18′47″W, 528 m, 14–31.i.2017, Malaise ”; MZUSP • 1 ♂; “ Antillanca , límite de la vegetación, 40°46′28″S, 72°12′41″W, 1054 m, 14.i–3.ii.2017, Malaise trap ”; INPA • 1 ♀; “ Anticura, Sendero Repucura , 40°39′53″S, 72°10′02″W, 447 m, 17.ii.2005, SS Nothofagus / Chusquea for. UCR AtoL C05-022”; CNC • 1 ♀; “ Pucatrihue , ii.1967, L.E. Peña col.”; MZUSP • 1 ♂, 4 ♀♀; “ Chiloé: Isla Chiloé, Dalcahue , iv.1968, L.E. Peña col.”; MZUSP • 2 ♀♀; same collection data as for preceding except “ i.1962 ”; MZUSP • 1 ♂; same collection data as for preceding except “ 17–22.i. [19]62, Scelolabes bivittatus det. B.J. Sinclair, 2014”; CNC • 8 ♂♂, 15 ♀♀; “ Ahoni Alto , ix.1988, L.E. Pena, Scelolabes bivittatus Phil., J.A. Rafael 1994 det.”; INPA .

Redescription

Male ( Fig. 3A, C–F )

MEASUREMENTS. Body length: 9.7 mm. Wing length: 8.0 mm.

HEAD. Frons black, shining, except lower half with pruinosity, dichoptic, slightly narrower than width of anterior ocellus. Very close eyes on face, Face 1.9× height of frons. Antenna ( Fig. 3D ) yellow, except postpedicel brown. Scape 1.5 × as long as pedicel, postpedicel lanceolate, about 1.5× length of scape and pedicel combined, with dense brown microtrichia; stylus about 1.8× length of antenna. Proboscis pale yellow, short; palpus pale yellow, short, oval, covered with dense yellow pruinosity and 1 long and slender setae. Two pairs of slender proclinate ocellar setae, anterior pair long, posterior pair very short. Occiput ( Fig. 3E ) black covered with dense grey pruinosity, postocular setae elongated, scattered, upper postoculars short; row of occipital setae elongated and strong.

THORAX. Shining. Pronotum ( Fig. 3E ) brown, except lateral margin yellow. Scutum ( Fig. 3F ) longer than wide, orange yellow, except by narrow dorsocentral stripe reaching posterior margin and not extend to postpronotal lobe, postalar callus brown, except spot on anterior margin yellow. Pleura ( Fig. 3A ) pale yellow. Scutellum ( Fig. 3F ) yellow with yellow pruinosity, with 1 pair of thin and short lateral yellow setae and 1 long and strong apical pair of black bristles. Mediotergite ( Fig. 3H ) yellow, except narrow black spot on lateral margin with yellow pruinosity. Acrostichal setulae multiserial (rows undefined), dorsocentrals uniserial, short, slender and sparse; several short and slender setae (acrostichals and dorsocentrals) on prescutelar region; notopleuron with slight grey pruinosity, 1 long and strong black notopleural bristle and several shorter, slender yellow setae; postpronotal lobe with several short and slender setae; 2 postalar setae, 1 long and strong anterior and 1 short and slender posterior.

WING ( Fig. 3G ). Membrane pale brown; pterostigma brown, elongate and narrow; dm cell shorter than basal cells, approximately 2.5× as long as wide, bm cell 1.3× length of cua cell; CuA vein incomplete, not reaching CuP vein. Halter ( Fig. 3C ) yellow, except spot slightly darker on knob; stem with a row of spine-like setulae.

LEGS ( Fig. 3A ). Yellow, except hind coxa, dorsal surface of mid and hind femora brown, apex of hind femur and base of hind tibia dark brown. Coxae subequal in length. Fore femur slightly swollen, hind femur strongly swollen. Chaetotaxy: legs with several long, slender and waved setae. Fore femur with 2 long and slender anterodorsal setae at apical half, 2 long and strong posterodorsal setae at apical half; mid femur with 1 row of anterodorsal, 1 row of posterodorsal and 1 row anteroventral of long and strong setae at apical half; hind femur with 1 row anterodorsal of long and strong setae on apical half, 1 posterodorsal of long and strong setae, two rows of spine-like setae, 1 anteroventral and 1 posteroventral, both inserted on small tubercles. Fore tibia with 1 short and slender dorsal basal setae; mid tibia with 2 long and strong posterodorsal setae, 1 basal and 1 at mid-length, 2 long and strong anterodorsal setae, 1 basal and 1 at mid-length, and 1 row of long and strong ventral setae at apex; hind tibia with 1 strong dorsal basal seta, 1 short and slender anterodorsal apical seta. Tarsi without outstanding bristles.

ABDOMEN. All tergites ( Fig. 3H ) brown, paler and weakly sclerotized anteriorly. Sternites weakly sclerotized, 1 and 2 hyalines, 3–8 pale brown. All tergites with long and slender setae on apical margin.

MALE TERMINALIA ( Fig. 4A–F ). Hypandrium ( Fig. 4A ) short, about 1.5× as long as wide, sub-quadrangular, covered with several long and slender setae, with a distal short projection on right margin with a group of long and slender setae. Epandrial lamellae ( Fig. 4A–D ) covered with several short and slender setae. Left epandrial lamella ( Fig. 4C ) slightly shorter, sub-rectangular, as long as wide; right epandrial lamella ( Fig. 4B ) broad, sub-ovate, as long as wide ( Fig. 4D ); presence of a long and slender dorsobasal projection behind right cercus, inserted close to bridge that links right to left epandrial lamella ( Fig. 4B ). Left surstylus ( Fig. 4E ) long, narrowing towards apex, with a row of long and slender setae on dorsal surface, setae inserted on tiny tubercles; right surstylus ( Fig. 4F ) subequal in length to left surstylus, clavated on base, both lobes with same length, short, with row of long and slender setae on ventral surface, setulae inserted on tiny tubercles near apex. Cerci symmetrical, short, subtriangular, weakly sclerotized, covered with short and slender setae ( Fig. 4B ). Subepandrial sclerite wider than long, with basal margin truncate and distal margin with slight middle concavity ( Fig. 4B ). Hypoproct sub-rectangular with two short projections, one at middle and one on left margin. Bacilliform sclerite asymmetrical with long and slender setae at distal half.

Female ( Fig. 3B )

Similar to male, except by absence of rows of short spine-like setae on hind femur. In female’s hind femur, the rows of anteroventral and posteroventral setae are long and strong. Moreover, the body of the female is smaller. Abdomen ( Figs 3B , 4G ) with tergite and sternite 8 fused. Sternite 8 covered with several short and slender setae, with slight constriction on posterior margin forming a bifid and sharpened projection, slenderer than in S. amorimi sp. nov. Tergite 10 absent. Sternite 10 sub-triangular, narrowly divided medially until ⅔ of length, covered with several short and slender setae. Cerci short, about ⅔ of sternite 10, covered with several short and slender setae.

Variation

Specimens of Scelolabes bivittatus show a wide variation in size, with the smallest specimens of the series measuring 6.5 mm and the biggest measuring 10 mm.

Remarks

Scelolabes bivittatus is similar to S. verasilvae sp. nov. by the scutum with a black intra-alar stripe and the abdominal tergites weakly sclerotized anteriorly. In addition, S. bivittatus has the scape and pedicel yellow and the black stripes on the scutum are restricted to intra-alar region, whereas in S. verasilvae the scape and pedicel are brown and the darker marks on the scutum are broader and occupy the dorsocentral region. Also, in S. bivittatus the hind femur is strongly swollen, whereas in S. verasilvae the hind femur is only slightly swollen.

Distribution

This species is known from southern Argentina and Chile ( Fig. 7B ).

Figures

Fig. 3. Scelolabes bivittatus Philippi, 1865 (INPA). A–B. Lateral habitus A. Male. B. Female. C. Halter, row of spine-like setulae in evidence. D. Antenna of male in lateral view. E. Occiput of male in dorsal view. F. Scutum of male in dorsal view. G. Wing of male. H. Abdomen of male in dorsal view.

Fig. 4. Scelolabes bivittatus Philippi, 1865. A–F. Male terminalia. A. Ventral view. B. Dorsal view. C. Left lateral view. D. Right lateral view. E–F. Surstyli in frontal view. E. Left. F. Right. G. Female terminalia in ventral view. Scale bars = 0.1 mm.

Fig. 7. Geographical records of Scelolabes Philippi, 1865. A. S. amorimi sp. nov. and S. verasilvae sp. nov. B. S. bivittatus Philippi, 1865.