Sclerocoelus frigidifrons, 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 : 59-60

Sclerocoelus frigidifrons sp. nov.

urn:lsid:zoobank.org:act:0E578D20-6A89-4DD3-A883-1E93D7063CC9

Figs 6I , 58–60

Etymology

This name reflects the collection of most of the type series from under vegetation that was in contact with the ground along cold, high elevation, streams (from the Latin words ‘ frigidus ’, meaning ‘cold’, and ‘ frons ’, meaning ‘leaf, foliage’).

Material examined

Holotype

ECUADOR • ♂; Pichincha, Cotopaxi National Park, Quebrada Mishahuaycu ; 3600 m a.s.l.; 26 Oct.–8 Nov. 1999; S.A. Marshall leg.; pans along stream; QCAZ debu00139771.

Paratypes

ECUADOR – Carchi • 3 ♀♀; Guandera Forest Reserve , 15 km E of San Gabriel; 3400 m a.s.l.; 1 Nov. 1999; S.A. Marshall leg.; hand; DEBU . – Loja • 1 ♂, 1 ♀; Podocarpus National Park, Cajanuma, Oso de Anteojos trail; 3000 m a.s.l.; 16–20 Feb. 2009; M. Pollet and A. De Braekeleer leg.; yellow pans; QCAZ . – Napo • 1 ♂; Baeza , W along road; 1500 m a.s.l.; 16–19 May 1987, L.D. Coote and B. V. Brown leg.; montane rainforest/pasture, Malaise trap; DEBU • 1 ♂, 1 ♀; near Lago Papallacta ; 6 Nov. 1999; S.A. Marshall leg.; under tree branches (brown leaves); QCAZ . – Pichincha • 18 ♂♂, 20 ♀♀; same data as for holotype; debu00339891/ MYCRO1019-22 sequenced for CO1-5’; DEBU • 18 ♂♂, 20 ♀♀; same data as for holotype; QCAZ • 1 ♂; same data as for holotype; 25 Oct. 1999; near stream, pan traps; DEBU • 1 ♂, 1 ♀; same data as for preceding; under streamside vegetation; QCAZ • 1 ♀; Bellavista Reserve ; 0°00′54″ S, 78°40′56″ W; 2200 m a.s.l.; 1 May 2011; S.A. Marshall leg.; treefall; QCAZ • 1 ♀; Campamento Pichan, near Nono ; 24 Oct. 1999; S.A. Marshall leg.; sweeping; QCAZ • 1 ♀; Valley near Hostería San Jorge, 10 km NW of Quito; 3000 m a.s.l.; 23 Oct. 1999; S.A. Marshall leg.; pans in grass pile; DEBU .

Description

BODY ( Fig. 58A ). Length 3.5–4.6 mm. Head dark brown, ventrolateral corners of frons slightly orange. Frontal width 2.3–2.4× frontal height. Three pairs of strong interfrontal bristles usually surmounting a fine fourth pair; anterior orbital 0.5–0.6× length of posterior. Palpus pale brown. Eye reduced, greatest height about 2.0 × shortest genal height; entire ventral margin of gena with row of setae. Thorax dark brown, scutum with slightly paler lateral edges. Two pairs of dorsocentral bristles (anterior pair distinct, 0.4× length of posterior pair) separated by 7–8 rows of acrostichal setulae. Membrane around prosternum bare. Legs dark brown, apices of fore and mid tibiae paler. Fore femur with 4–5 large ventral preapical setae. Dorsal surface of mid tibia with an offset pair of setae at about ⅓, a large anterior seta at about ½, and a pair of large, curved setae at about 4/5. Ventral surface of male mid tibia with two rows of stout setae along apical third. Wing ( Fig. 6I ) slightly infuscate. CS2 1.0–1.1 × CS3. Alula very broad. Halter brown.

MALE ABDOMEN ( Figs 58B–C , 59 ). Dark brown, posterior edges of tergites sometimes slightly desclerotized. T2–5 and S2–4 uniformly long-setose with large posterolateral setae. S5 rectangular, 1.2× length of S4, posterolaterally long-setose with a medial, T-shaped, pale area and a posteromedial, V-shaped, dark, long-setose area flanked by broad, pale, bare areas. Anterior flange of S6+7 small, 3.0× as long as wide. Sclerite A pale, indistinct from S6+7; sclerite B dark, arched; sclerite C dark, fused to sclerite A; sclerites D and E fused, forming a large, dark, trapezoidal sclerite; sclerite F large, triangular, apical half angled inwards, wrapping around sclerite D+E; sclerite G dark, stout; ring sclerite well sclerotized and fused to sclerite G. Epandrium large, 0.5× length of S8, height 1.8× maximum length and 0.8× maximum width, densely long-setose; anal fissure large and ovoid; perianal pads weakly developed. Pseudocercus absent; halves of subepandrial sclerite very short, well separated, and curved. Cercus small, rectangular with a small, triangular, ventral lobe, cerci narrowly fused medially to form a subanal plate. Hypandrium with very long, thin anteromedial apodeme. Surstylus orange, subquadrate, bulging, ventral third densely setose, setae of inner surface thickened. Postgonite elongate, basal third with a rounded posterolateral lobe, apical two-thirds gently tapered and slightly curved. Phallapodeme large, sinuate with a large, twisted flap of sclerotized tissue on right side, connecting ventrolaterally at base to dorsolaterally at apex; basiphallus elongate, basal third tapered, resembling base of a femur; distiphallus elongate, largely membranous, without any distinct supporting sclerites.

FEMALE ABDOMEN ( Fig. 60 ). T7 broad, simple; T8 divided into a small, pale, dorsal sclerite and two large, dark, lateral sclerites, posterolateral corners very slightly expanded and rounded. Epiproct large, ovoid with posteromedial point, medially desclerotized, and entirely setulose. Cercus elongate, apically pointed with long apical, dorsal, and apicoventral setae. S7 broad, posteromedially expanded into a rounded, desclerotized tab, posteriorly with 7–8 large posterior setae; S8 entirely membranous. Hypoproct with dense setulae in apical half. Three spermathecae, bulb stout, spherical, finely striate with a shallow apical and a very deep basal invagination, invaginations joined centrally.

Distribution

Neotropical: Ecuador.

Remarks

Sclerocoelus frigidifrons sp. nov. is externally most similar to Sclerocoelus cubus sp. nov., but differs by its larger size (3.5–4.6 mm), smaller eye (~2.0 × genal height), rounded, saddle-shaped epandrium, and the male S5 with unmodified setae. This species has distinct cerci fused basally into a subanal plate but not differentiated into separate pseudocerci or subcerci. These characters suggest that S. frigidifrons and its brachypterous sister species S. aduncus sp. nov. are among the few species in the genus that are basal to the large, derived groups characterized by separate subcerci and pseudocerci. With the exception of S argentinensis sp. nov., the species that have the plesiomorphic subanal plate and simple cerci are associated with wet, green plant material in high elevation cloud forests or elfin forests in the Andes.

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. 58. Sclerocoelus frigidifrons sp. nov. A. Male paratype habitus, lateral view (debu00142443). B. Male paratype terminalia, posterior view (debu00139644). C. Male paratype terminalia, lateral view (debu00139644). Abbreviations: cer =cercus; epa =epandrium; se =subepandrial sclerite; ss= surstylus. Scale bars: A= 1.0 mm; B–C =0.25 mm.

Fig. 59. Sclerocoelus frigidifrons sp. nov., paratype (debu00139644). 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. 60. Sclerocoelus frigidifrons sp. nov., paratype (debu00142033). 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 =0.04 mm.