Sclerocoelus binus 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 binus

description: Sclerocoelus binus sp. nov.
urn:lsid:zoobank.org:act: DD38063F-484E-408F-B8B3-D0E2896CB4D0
Figs 5F, 23–25
Etymology
This name refers to the two, very long, distinctive setae flanking the posteromedial patch of setulae on the male S5 (from the Latin ‘ binus ’, meaning ‘pair, occurring twice’), but it could equally well refer to the unusual reduction of the spermathecal number to two from the usual three.
Material examined
Holotype
BOLIVIA • ♂; La Paz, 23 km NE of Caranavi; 14 Apr. 2001; S.A. Marshall leg.; roadside/stream sweep; CBFC debu00165447.
Paratypes
BOLIVIA – La Paz • 42 ♂♂, 12 ♀♀; same data as for holotype; CBFC • 40 ♂♂, 11 ♀♀; same data as for holotype; debu00165453 / MYCRO1025-22 sequenced for CO1-5’; DEBU • 2 ♂♂; 0.5 km SE of Coroico; 16°11′ S, 67°44′ W; 15 Apr. 2001; S.A. Marshall leg.; CBFC • 1 ♂; Apa-Apa, 8 km S of Chulumani; 16°35′36″ S, 68°51′12″ W; 1960 m a.s.l.; 9 Mar. 2001; A. Freidberg leg.; USNM.
COSTA RICA – Cartago • 1 ♂; Tapantí National Park, Arboles Caídos Trail; 1300 m a.s.l.; 9/ 11 Oct. 1999; S.A. Marshall leg.; MNCR • 3 ♂♂; Tapantí National Park, outside near west entrance; 1150 m a.s.l.; 8–9 Oct. 1999; Marshall and Buck leg.; sweep trail; DEBU • 2 ♂♂; same data as for preceding; MNCR. – Heredia • 1 ♂; 16 km SSE of La Virgen; 10°16′ N, 84°05′ W; 1050–1150 m a.s.l.; 9–21 Feb. 2001; transect; DEBU • 2 ♂♂; same collection data as preceding; 21 Mar. 2001; MNCR. – Puntarenas • 1 ♂; Monteverde Biological Reserve; 1500 m a.s.l.; 11–13 Jun. 2000; S.A. Marshall leg.; cloud forest; DEBU • 1 ♂; same data as for preceding; 11 Jun. 2000; M. Buck leg.; sweep; MNCR • 3 ♂♂; Monteverde Biological Reserve; 1500 m a.s.l.; 14 Jun. 2000; M. Buck leg.; sweeping treefall and trail; MNCR • 4 ♂♂; same data as for preceding; treefall sweep and pans; DEBU.
ECUADOR – Napo • 3 ♂♂; El Chaco; 2000 m a.s.l.; 15–23 Feb. 1983; L. Masner and M. Sharkey leg.; Malaise trap; CNCI. – Pichincha • 1 ♂; 3.5 km SE of Tandayapa; 28 Oct. 1999; S.A. Marshall leg.; in green leaf litter (treefall); QCAZ • 1 ♂; Bellavista Cloud Forest Reserve; 0°01′13″ S, 78°40′30″ W; 2200 m a.s.l.; 9–13 May 2009; S.A. Marshall leg.; DEBU.
PERU – Cusco • 1 ♂; Cock-of-the-Rock Lodge, NE Paucartambo; 13°03′18″ S, 71°32′42″ W; 1120 m a.s.l.; 4–9 Nov. 2007; D. Brzoska leg.; flight-intercept trap; MUSM.
VENEZUELA – Aragua • 1 ♂; Henri Pittier National Park, 12 km W of Maracay, on Choroni Road; 1290 m a.s.l.; 7 Mar. 1995; S.A. Marshall leg.; DEBU.
Description
BODY (Fig. 23A). Length 2.9–3.5 mm. Head brown, lower third of frons and antennae orange; face and gena orange-brown. Frontal width 2.2–2.3× frontal height. Three pairs of strong interfrontal bristles surmounting a very fine fourth pair; anterior orbital 0.5–0.6 × length of posterior. Palpus pale brown. Eye very large, greatest height about 5.0 × shortest genal height. Thorax brown, scutum with paler lateral edges. Two pairs of dorsocentral bristles (anterior pair only slightly larger than surrounding acrostichal setulae) separated by 7–8 rows of acrostichal setulae. Membrane around prosternum with a small, setula-bearing sclerite. Legs brown, trochanters pale. Fore femur with three large ventral preapical setae. Ventral surface of male mid tibia with two rows of stout setae in apical third. Wing (Fig. 5F) slightly infuscate. CS2 0.7–0.8 × CS3. Halter pale brown.
MALE ABDOMEN (Figs 23B–C, 24). Dark brown, posterior edges of tergites sometimes slightly desclerotized. T2–5 and S2–4 uniformly long-setose with large posterolateral setae; preabdomen relatively long and typically curved downwards. S5 rectangular and short, 1.0× as long as S4, laterally long-setose, posteromedially with a patch of dense setulae and a pair of very long setae. Anterior flange of S6+7 weakly developed. Sclerite A lightly sclerotized but distinct from S6, with two long bristles in addition to sensory setulae; sclerite B small, narrow; sclerite C absent; sclerite D elongate, L-shaped; sclerites E and F large, bifurcate, the right lobes parallel, long and extending posteriorly; sclerite G well developed, elongate, and sinuate; ring sclerite large but thin. Epandrium large, 2.3× length of S8, height 1.2 × maximum length and 0.8× maximum width, sparsely setose; perianal pads weakly developed but densely setulose. Pseudocercus large, elongate, separate from epandrium, with three setae; halves of subepandrial sclerite very narrow, separate and expanded medially, articulating with medially contiguous posterodorsal lobes of subcercus. Subcercus elongate, inner part forming a broad, flat, triangular anterior lobe, outer part smaller with narrow posteromedial lobes and broad lateral lobe articulating with surstylus and epandrium. Hypandrium long, anteromedial apodeme narrow. Surstylus large, divided into a broad, setose anteroventral lobe and a setulose posterior lobe, inner surface with a prominent, carinate, anteriorly projecting lobe. Postgonite broad, apically bilobed, and slightly curved; anterior lobe truncate, posterior lobe digitate. Phallapodeme long but narrow; basiphallus short, basally with a central carina and lateral expansions; distiphallus largely membranous, dorsoventrally flattened with S-shaped ventrolateral sclerites.
FEMALE ABDOMEN (Fig. 25). T7 broad, simple; T8 divided into a small, pale, dorsal sclerite and two broad, dark, lateral sclerites, posterolateral corners expanded posteriorly. Epiproct broad, shield-like, medially desclerotized, and entirely setulose. Cercus slightly elongate, blunt, with long, relatively stout apical and preapical setae. S7 broad, posteromedially pointed with two large medial setae and two large posterolateral setae; S8 entirely membranous, only two minute setulae indicating its presence. Two spermathecae, bulb stout, bean-shaped, finely striate with a deep invagination on one end and a shallow invagination beside insertion point of duct, both invaginations with a finger-like, central process.
Distribution
Neotropical: Bolivia, Costa Rica, Ecuador, Peru, Venezuela.
Remarks
Several features, including an elongate, curved male abdomen, large bilobed surstylus, and a setose prosternum, suggest a relationship between S. binus sp. nov. and S. caribensis and other species in the S. galapagensis group. Sclerocoelus binus, however, has only a single pair of prosternal setae and lacks the large perianal pads characteristic of S. caribensis and related species. Sclerocoelus binus has an unusually wide distribution, extending from Costa Rica to Bolivia, but the distinctive male genitalia are consistent throughout the range. The holotype and many of the paratypes were collected at the same Bolivian locality as half a dozen congeners (S. andensis, S. brasilensis, S. bucki sp. nov., S. caligarius sp. nov., S. copiosus sp. nov., and S. xynos sp. nov.). Most of the type specimens were swept over wet leaf litter along streams, ditches or treefalls.
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 30-31, DOI: 10.5852/ejt.2025.979.2803, http://zenodo.org/record/14980852