Sclerocoelus tridens Kuwahara, Marshall & Paiero, 2025, sp. nov.
Creators: name: Kuwahara, Gregory K.
name: Marshall, Stephen A.
name: Paiero, Steven M.
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Sphaeroceridae
Sclerocoelus
Sclerocoelus tridens

description: Sclerocoelus tridens sp. nov.
urn:lsid:zoobank.org:act: 298959FA-DEC2-4C86-A506-695F84F8AC63
Figs 9F, 139–141
Etymology
This name refers to the additional ventromedial strip of slightly thickened setulae on the female hypoproct, giving a trident-shaped pattern of setulae (from the Latin ‘ tridens ’, meaning ‘three-tined, having three prongs or teeth’).
Material examined
Holotype
ECUADOR • ♂; Napo, Quito–Baeza Road; 4000 m a.s.l.; 10–18 Feb. 1983; L. Masner leg.; elfin forest, pan traps; QCAZ.
Paratypes
BOLIVIA – Cochabamba • 1 ♂; South Corani, Yungas El Chapare; 2900 m a.s.l.; 29–31 Jan. 1976; L.E. Peña leg.; CBFC.
ECUADOR – Napo • 1 ♀; Quito-Baeza Pass; 4000 m a.s.l.; 1 Mar. 1979; S.A. Marshall leg.; elfin forest, dung trap; QCAZ. – Pichincha • 1 ♂; 12 km NW of Papallacta west slope; 3840 m a.s.l.; 11–12 Oct. 1987; C. Young, R. Davidson and J. Rawlins leg.; subpáramo mixed grass/woodland; CMNH • 1 ♂; 46 km E of Quito; 4000 m a.s.l.; 2–6 Mar. 1976; S. Peck leg.; elfin forest, dung; DEBU • 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 ♂; Cotopaxi National Park, Lago Limpiopungo; 3800 m a.s.l.; 25 Oct. 1999; R. Anderson leg.; paramo, shrub litter; DEBU • 1 ♀; Cotopaxi National Park, Quebrada Mishahuaycu; 3600 m a.s.l.; 26. Oct.–8 Nov. 1999; S.A. Marshall leg.; pans along stream; DEBU.
Description
BODY (Fig. 139A). Length 3.2–4.4 mm. Head dark brown, lower frons, face, and antennae orange; anterior third of gena orange. Frontal width 2.2–2.3× frontal height. Three pairs of strong interfrontal bristles surmounting a very fine fourth pair; anterior orbital 0.4–0.5 × length of posterior. Palpus yellow. Eye large, greatest height about 4.0 × shortest genal height. Thorax dark brown, scutum with 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 bare. Legs brown, hind tibia darker. Fore coxa with row of stout setae along inner surface; fore femur with three large ventral preapical setae. Ventral surface of male mid tibia with two rows of stout setae in apical two-thirds. Wing (Fig. 9F) hyaline. CS2 subequal to CS3. Halter pale brown with white apex.
MALE ABDOMEN (Figs 139B–C, 140). Dark brown, posterior edges of tergites sometimes slightly desclerotized. T2–5 and S2–4 uniformly long-setose with large posterolateral setae. S5 rectangular, 1.0× length of S4, laterally setose, posterior margin unpigmented with a row of long, tubercle-based setae and two rows of 4–5 short, stout, posteromedial setae. Anterior flange of S6+7 small, weakly developed. Sclerite A small, fused to S6+7; sclerite B long, dark, arched into genital pouch; sclerite C elongate with a small posteromedial lobe; sclerite D dark, subtriangular, and lying against posteromedial margin of S5; sclerite E absent; sclerites F and G fused into a large, inflated sclerite with dense setulae on left third; ring sclerite incorporated into posterior margin of sclerite F+G. Epandrium moderate, 0.5× length of S8, height 1.7× maximum length and 0.8× maximum width, uniformly setose; perianal pads weakly developed. Pseudocercus absent; halves of subepandrial sclerite thin, slightly curved, and fused medially. Subcercus simple, triangular, posteriorly setulose and ventrally extended as a curved, almost bare process. Hypandrium with thin anteromedial apodeme. Surstylus slightly elongate, distally setose, posterolaterally convex and setulose, anterolaterally bare and concave, inner surface flat and bare. Postgonite simple, elongate, and apically tapered. Phallapodeme long, apex dorsoventrally flattened; basiphallus stout and connected to distiphallus by a short, neck-like distal part; distiphallus largely membranous with a small dorsal sclerite and a pair of sinuate ventral sclerites.
FEMALE ABDOMEN (Fig. 141). T7 broad, simple; T8 entire but dorsally desclerotized, appearing as two lateral sclerites, posteroventral corners rounded and expanded. Epiproct elongate, medially pale, appearing split, and entirely bare of setulae. Cercus elongate, apically pointed with large apical and dorsal setae. S7 rounded posteriorly, broadly desclerotized with six large posterior setae; S8 entirely membranous/absent. Hypoproct with a sclerotized ventromedial strip. Vagina with an internal, dark, crescent-shaped sclerite. Three spermathecae, bulb stout, spherical, finely striate with a broad, deep invagination on both ends.
Distribution
Neotropical: Bolivia, Ecuador.
Remarks
Sclerocoelus tridens sp. nov. can be reliably separated from all congeners by the anteroventral strip of the female hypoproct covered in slightly thickened setulae, transverse crescent-shaped vaginal sclerite, and thin, straight postgonite. Although Sclerocoelus tridens has clearly differentiated subcerci that are well separated from the epandrium, they are relatively simple and there is no trace of the pseudocercus characteristic of the S. galapagensis, S. regularis, and S. dasysternum groups. As is often the case for Sclerocoelu s species outside those derived species groups, S. tridens is a high Andean species.
description: Published as part of Kuwahara, Gregory K., Marshall, Stephen A. & Paiero, Steven M., 2025, A revision of the genus Sclerocoelus Marshall (Diptera: Sphaeroceridae), pp. 1-277 in European Journal of Taxonomy 979 on pages 116-117, DOI: 10.5852/ejt.2025.979.2803, http://zenodo.org/record/14980852