Sclerocoelus flavus, Kuwahara & Marshall & Paiero, 2025

Kuwahara, Gregory K., Marshall, Stephen A. & Paiero, Steven M., 2025, A revision of the genus Sclerocoelus Marshall (Diptera: Sphaeroceridae), European Journal of Taxonomy 979, pp. 1-277 : 57-59

Sclerocoelus flavus sp. nov.

urn:lsid:zoobank.org:act:FAFDB45E-58EE-4071-9075-86647AE8E0AB

Figs 6H , 55–57

Etymology

This name refers to the bright yellow colouration of the head and legs (from the Latin ‘ flavus ’, meaning ‘yellow, golden’).

Material examined

Holotype

VENEZUELA • ♂; Mérida, Sierra Nevada National Park, Laguna Negra ; 4000 m a.s.l.; 28–30 Aug. 1992; L. Masner leg.; elfin forest , yellow pan traps; USNM.

Paratype

VENEZUELA – Mérida • 1 ♂, 1 ♀; Apartaderos, Laguna Negra ; 3350 m a.s.l.; 1–29 Jul. 1989; S.B. Peck and J. Kukalova-Peck leg.; treeline moss forest, carrion traps; FMNH .

Description

BODY ( Fig. 54A ). Length 3.2–3.4 mm. Head yellow, dark brown at level of ocelli and behind; center of frons reddish, antenna orange. Frontal width 1.8× frontal height. Three pairs of strong interfrontal bristles surmounting a fine fourth pair (holotype has a fourth large interfrontal bristle on one side); anterior orbital 0.5× length of posterior. Palpus yellow. Eye large, greatest height about 4.0 × shortest genal height. Thorax yellow, scutum brown with slightly paler lateral edges. Two pairs of dorsocentral bristles (anterior pair distinct, 0.4× length of posterior pair) separated by 6–7 rows of acrostichal setulae. Membrane around prosternum bare. Legs yellow, tibiae slightly darker. Fore femur with three large ventral preapical setae. Dorsal surface of mid tibia with an additional small anterior seta in distal half. Ventral surface of male mid tibia with two rows of stout setae along apical quarter. Wing ( Fig. 6H ) strongly shortened, extending to end of T2; strongly infuscate. M 1 and M 4 converging apically, eliminating dmm; cell bm-m pointed. CS2 1.6× CS3. Halter reduced to a small brown nub.

MALE ABDOMEN ( Figs 55B–D , 56 ). Dark brown, posterior edges of tergites sometimes slightly desclerotized. T2–5 and S2–4 uniformly long-setose with large posterolateral setae. S5 very broad, 1.3 × length of S4, largely bare except a group of 3 posteromedial setae, two patches of long setae on either side of a deep, setulose, posteromedial emargination, and a patch of setae on left side, anterior margin with a broad anteromedial expansion. Anterior flange of S6+7 small, triangular, 1.0 × as long as wide. Sclerite A a short flap fused to S6+7; sclerites B and C absent; sclerite D small, ovoid, and fused to sclerite E via a short ‘neck’; sclerite E triangular, right side darker and apex curved dextrally; sclerites F and G fused, sclerite F elongate on left side to curve around sclerite E; sclerite G short, concave; ring sclerite moderately developed. Epandrium large, 0.7 × length of S8, height 1.7 × maximum length and 0.7 × maximum width, uniformly long-setose; anal fissure ovoid; perianal pads weakly developed. Pseudocercus absent; halves of subepandrial sclerite weakly developed. Subcerci fused anteromedially, short, triangular with apex curved posteriorly. Hypandrium with sinuate anteromedial apodeme. Surstylus large, 2.5 × as long as deep, concave, long-setose on inner and outer surfaces, subrectangular with curved anteroventral corner and a long, pointed posterodorsal lobe. Postgonite short, subtriangular, gently curved with apex bent forwards abruptly. Phallapodeme very large, sinuate; basiphallus very large, dorsal part bulbous, ventral part split into two lobes: anterior lobe short, connecting to posterodorsal corner of distiphallus, posterior lobe very large, medially swollen and apically tapered, curved downwards and emarginate, posterior lobe almost as large as postgonite; distiphallus almost entirely membranous, large ventral lobes supported by a tubular basal part.

FEMALE ABDOMEN ( Fig. 57 ).T7broad, simple;T8 divided into two large, dark, lateral sclerites, posterolateral corners slightly expanded and rounded. Epiproct large, shield-like with posteromedial point, medially desclerotized, and setulose largely in the desclerotized area. Cercus stout, apically rounded with long apical, dorsal, and apicoventral setae. S7 broad, subtriangular, posteriorly with 11–12 large posterior setae; S8 entirely membranous. Hypoproct with dense setulae in apical half. Three spermathecae, bulb cylindrical, apical third slightly constricted, finely striate with an apical and basal invagination, both with a small, finger-like, central process.

Remarks

Sclerocoelus flavus sp. nov., along with the sympatric S. meridensis sp. nov., can be distinguished from all other species of Sclerocoelus by the characteristically abbreviated wing ( Fig. 6H ) with a non-reduced alula. Sclerocoelus flavus can be separated from S. meridensis by its yellowish head, thorax, and legs, and characters of the male and female terminalia. This species is known only from high elevation sites from at or near the treeline in Venezuela and is one of the most basal species of the genus, with the complex genital pouch sclerites that define the genus but without the apomorphic asymmetrical spermathecae or differentiated subcerci of more derived species.

Figures

Fig. 6. Sclerocoelus Marshall, 1995, left wings, ventral view. A. Sclerocoelus costaricensis sp. nov. B. Sclerocoelus cubus sp. nov. C. Sclerocoelus dasysternum sp. nov. D. Sclerocoelus dominicensis sp. nov. E. Sclerocoelus dryadalis sp. nov. F. Sclerocoelus elephas sp. nov. G. Sclerocoelus espeletia sp. nov. H. Sclerocoelus flavus sp. nov. I. Sclerocoelus frigidifrons sp. nov. J. Sclerocoelus grandicercus sp. nov. Scale bars: A–J =0.5 mm.

Fig. 55. Sclerocoelus flavus sp. nov. A. Male paratype habitus, lateral view (debu01041019). B. Holotype left surstylus, posterior view (USNM). C. Male holotype terminalia, lateral view (USNM). D. Holotype cercus, posterior view (USNM). Abbreviations: cer =cercus; epa=epandrium; ss=surstylus. Scale bars: A=1.0 mm; B–D =0.25 mm.

Fig. 56. Sclerocoelus flavus sp. nov., male holotype (USNM). A. Aedeagus and associated structures, lateral view. B. Male S5 and genital pouch, ventral view.Abbreviations:bp = basiphallus; dp =distiphallus; pg =postgonite; ph =phallapodeme. Scale bars: A=0.13 mm; B= 0.25 mm.

Fig. 57. Sclerocoelus flavus sp. nov., paratype (debu01041018). A. Female terminalia, dorsal view. B. Female terminalia, ventral view. C. Female terminalia, lateral view. D. Spermatheca. Scale bars: A–C= 0.25 mm; D =0.03 mm.

Fig. 54. Sclerocoelus espeletia sp. nov., paratype. A. Aedeagus and associated structures, lateral view. B. Male S5 and genital pouch, ventral view. Abbreviations: bp = basiphallus; dp =distiphallus; epi =epiphallus; pg =postgonite; ph =phallapodeme. Scale bars: A=0.13 mm; B=0.25 mm.