Sclerocoelus chilensis, 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 : 39-40

Sclerocoelus chilensis sp. nov.

urn:lsid:zoobank.org:act:12116740-67B2-4A52-BCB6-A6E1F4C79981

Figs 5I , 32–33

Etymology

This name reflects the apparent restriction of this species to Chile, where it is the only known species of Sclerocoelus .

Material examined

Holotype

CHILE • ♂; Valparaíso, Portillo, Río Juncalillo ; 32°50′58″ S, 70°07′59″ W; 2500 m a.s.l.; 10 Dec. 2008; Kits and Marshall leg.; stream vegetation; MNNC debu00310625.

Paratype

CHILE – Valparaíso • 1 ♂; same data as for holotype; DEBU debu00310638 .

Description

BODY ( Fig. 32A ). Length 3.0– 3.1 mm. Head dark brown, ventrolateral corners of frons orange; gena slightly reddish. Frontal width 2.5× frontal height. Three pairs of strong interfrontal bristles surmounting a fine fourth pair; anterior orbital 0.4–0.5× length of posterior. Palpus yellow. Eye reduced, greatest height about 2.0× shortest genal height. Thorax dark brown, scutum with slightly paler lateral edges. Two pairs of dorsocentral bristles (anterior pair distinct, 0.5× length of posterior pair) separated by 7–8 rows of acrostichal setulae. Membrane around prosternum darkened but bare. Legs brown, femora apically and tibiae basally paler. Fore femur with 3–4 large ventral preapical setae. Dorsal surface of mid tibia lacking small anterior seta in distal half. Ventral surface of male mid tibia with two rows of stout setae along apical half. Wing ( Fig. 5I ) slightly infuscate. CS2 subequal to CS3. Halter brown.

MALE ABDOMEN ( Figs32B–C , 33 ).Dark brown, posterior edges of tergites sometimes slightly desclerotized. T2–5 and S2–4 uniformly long-setose with large posterolateral setae. S5 broad, asymmetrical, medially 1.0× length of S4, left side reduced anteriorly and posteriorly, setose in posterior half with a short, darkened, setulose posteromedial patch. Anterior flange of S6+7 not developed. Sclerite A large, rectangular, setulose; sclerite B very large and flat, curved to right side and laying parallel to S5; sclerite C triangular, fused to right extension of S6+7, situated over and to the left of sclerite D+E; sclerites D and E fused, triangular, posteriorly split with a slight overlap of apices; sclerite F large, setulose with a dark, sinuate apodeme on left side; sclerite G large, bulging, broadly fused to right side of sclerite F; ring sclerite well developed. Epandrium large, 0.8× length of S8, height 1.4 × maximum length and 0.7× maximum width, uniformly long-setose; perianal pads weakly developed. Pseudocercus absent; halves of subepandrial sclerite broad, strongly arched, and medially fused. Subcercus large, basal half broad in posterior view and angled anteroventrally in lateral view, apical half flattened in posterior view, tapered and angled posteroventrally in lateral view. Hypandrium with thin, sinuate anteromedial apodeme. Surstylus large, triangular, long-setose with a blade-like, inner anterobasal lobe and a curved, preapical, posterodorsal emargination. Postgonite large, strongly sinuate, and evenly tapered. Phallapodeme very large with a short dorsal ‘fin’; basiphallus stout and connected to distiphallus by a neck-like distal part; distiphallus short, largely membranous with a broad, sinuate dorsal sclerite and a pair of sinuate lateral sclerites.

FEMALE ABDOMEN. Female unknown.

Distribution

Neotropical: Chile.

Remarks

Sclerocoelus chilensis sp. nov. is one of two species that has a darkened membrane around the prosternum, the other being S. rectangularis . Sclerocoelus chilensis can be readily separated from S. rectangularis by its smaller eye, smaller epandrium with an ovoid anal fissure, subtriangular subcercus, and bilobed genital pouch sclerite D. Sclerocoelus chilensis , the southernmost species of the genus, is known from small deposits of plant material along a stream in an otherwise dry and barren alpine landscape. An apparent restriction to the moist microhabitat created by bits of vegetation along high Andean streams or similar high elevation microhabitats is a characteristic of several related species, including S. lutosus sp. nov., S. punensis sp. nov., and S. tridens sp. nov.

Figures

Fig. 5. Sclerocoelus Marshall, 1995, left wings, ventral view. A. Sclerocoelus aduncus sp. nov. B. Sclerocoelus alpinus sp. nov. C. Sclerocoelus altus sp. nov. D. Sclerocoelus argentinensis sp. nov. E. Sclerocoelus azulensis sp. nov. F. Sclerocoelus binus sp. nov. G. Sclerocoelus bucki sp. nov. H. Sclerocoelus caligarius sp. nov. I. Sclerocoelus chilensis sp. nov. J. Sclerocoelus copiosus sp. nov. Scale bars: A–J= 0.5 mm.

Fig. 32. Sclerocoelus chilensis sp. nov. A. Male holotype habitus, lateral view (debu00310625). B. Male paratype terminalia, posterior view (debu00310638). C. Male paratype terminalia, lateral view (debu00310638). Abbreviations: epa=epandrium; sc =subcercus; se =subepandrial sclerite; ss= surstylus. Scale bars: A= 1.0 mm; B–C =0.25 mm.

Fig. 33. Sclerocoelus chilensis sp. nov., paratype (debu00310638). 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–B= 0.25 mm.