Sclerocoelus synorios 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 synorios

description: Sclerocoelus synorios sp. nov.
urn:lsid:zoobank.org:act: 86808438-F122-4007-9C83-FF8343EBB199
Figs 9D, 133–135
Etymology
This name reflects the distribution of this species, which spans the border between Mexico and the United States (from the Greek ‘ sýnoro ’, meaning ‘border, boundary, limit’).
Material examined
Holotype
MEXICO • ♂; Baja California Sur, Sierra Laguna, La Laguna, 31.5 km ENE of Todos Santos; 1800 m a.s.l.; 12–18 Dec. 1979; C.E. Griswold leg.; CAS.
Paratypes
MEXICO – Baja California Sur • 1 ♀; same data as for holotype; CAS. – Chiapas • 2 ♂♂; 5 km NE of Coapilla; 17°10′34″ N, 93°07′59″ W; 1990 m a.s.l.; 25 May–14 Jun. 2008; 2° mesophyll forest, Malaise trap; DEBU • 2 ♂♂, 1 ♀; same data as for preceding; UVGC. – Mexico • 1 ♀; 1.6 km E of Ixtapan de la Sal, km 78; 1900 m a.s.l.; 31 Aug.–6 Sep. 1971; A. Newton leg.; “Trop/Dec/Jun.”, human dung; FMNH.
UNITED STATES OF AMERICA – Arizona • 1 ♂; Flagstaff, Oak Creek Canyon, at Sterling Canyon; 1800 m a.s.l.; 17–25 Jul. 1979; S. and J. Peck leg.; riparian woods, Malaise trap; DEBU.
Description
BODY (Fig. 133A). Length 2.3–3.6 mm. Head dark brown, lower fifth of frons orange, orange area extending along orbital plate; gena reddish. Frontal width 2.2–2.3× frontal height. Three pairs of strong interfrontal bristles surmounting a very fine fourth pair; anterior orbital 0.6–0.7 × length of posterior. Palpus orange. Eye large, greatest height about 3.5× shortest genal height. Thorax dark brown, scutum with 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 dark brown, tarsomeres paler. Fore femur with three large ventral preapical setae. Ventral surface of male mid tibia with two rows of stout setae in apical quarter. Wing (Fig. 9D) slightly infuscate. CS2 0.8–0.9 × CS3. Halter brown.
MALE ABDOMEN (Figs 133B–C, 134). Dark brown, posterior edges of tergites sometimes slightly desclerotized. T2–5 and S2–4 uniformly long-setose with large posterolateral setae. S5 rectangular, 2.0× as long as wide, sparsely setose, anterior half with two narrow, converging pale stripes, posteromedially with a large, dark, slightly bulging patch of dense setulae flanked by pale areas and dark, setose patches. Anterior flange of S6+7 very large, 1.1 × as long as wide. Sclerite A small, dark; sclerite B large, broad, arched; sclerite C absent; sclerite D short, broad, club-shaped, arising from left side of posteromedial process of S5; sclerite E elongate, sinuate, slightly folded over itself; sclerite F large, rectangular with an elongate, deflexed, apicoventral process on left side; sclerite G elongate, curved; ring sclerite dark, small. Epandrium moderate, 0.7× length of S8, height 1.1 × maximum length and 0.7 × maximum width, uniformly setose, posterior setae larger, posteroventral corner slightly emarginate; anal fissure broadly triangular; perianal pads strongly protruding, elongate, dark, curved, dorsally setulose, ventrally setose. Pseudocercus large, separate from epandrium, bearing three strong setae; halves of subepandrial sclerite narrow, strongly arched, and fused medially. Subcercus with a short inner part, articulating with subepandrial sclerite dorsally, forming a small, posteriorly bent process ventrally, and an outer part with short lobes articulating with surstylus and subcercus. Hypandrium with narrow, sinuate anteromedial apodeme. Surstylus subquadrate, slightly elongate, laterally setulose, ventrally setose, inner surface with a large carinate lobe extending from near middle to anterodorsal corner. Postgonite flattened, curved anteriorly, apex slightly expanded, pale, and striate. Phallapodeme large, apex dorsoventrally flattened; basiphallus strongly dorsoventrally flattened basally, apically notched, and distally expanded, extending along dorsal margin of distiphallus; distiphallus short, with a pale, broad, sheath-like ventral sclerite and a pair of dark, narrow dorsolateral sclerites.
FEMALE ABDOMEN (Fig. 135). T7 broad, simple; T8 divided into a small, pale, dorsal sclerite and two large, dark, lateral sclerites, posterolateral corners expanded posteriorly. Epiproct broad, medially desclerotized (especially posteromedially), and entirely setulose. Cercus elongate, apically pointed with long apical and dorsal setae. S7 broad, posteromedially pointed with 4–5 large posterior setae; S8 reduced to a thin, curved sclerite with dark lateral edges. Three spermathecae, bulb stout, bean-shaped, finely striate with a deep, broad invagination on thicker end, invagination with a finger-like, central process.
Distribution
Nearctic: United States of America; Neotropical: Mexico.
Remarks
Sclerocoelus synorios sp. nov. is superficially similar to S. recurvatus sp. nov. but differs by the asymmetrical (strongly reduced on the right side) male S5 with a stout posteromedial setulose patch, elongate surstylus, strongly reduced female S8, and relatively stout hypoproct. Sclerocoelus synorios is a mostly Mexican species also known from a single record just across the border into Arizona, making it one of three Sclerocoelus species known from the United States. It is one of eight congeners found in Mexico, two of which are known only from Mexico. One of the apparent Mexican endemics (S. rostrum sp. nov.) is in the S. dasysternum group along with S. synorios sp. nov.; the other endemic (S. pararegularis sp. nov.) is in the S. regularis group.
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 110-111, DOI: 10.5852/ejt.2025.979.2803, http://zenodo.org/record/14980852