Pelastoneurus arcuatus Loew 1861
Creators: name: Soares, Matheus M. M.
name: Runyon, Justin B.
name: Capellari, Renato S.
name: Ale-Rocha, Rosaly
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Dolichopodidae
Pelastoneurus
Pelastoneurus arcuatus

description: The arcuatus -group of Paraclius
Diagnosis (males). Head. Face gradually narrowing below (funnel-shaped), the narrowest point slightly wider than the mid ocellus (e.g. Figs 1D, 2C, 7E). Clypeus short, about 1/4 as long as face (e.g. Figs 1D, 2C, 8C, 11C). Palpus oval, short, with 1 strong apical seta, shorter than palpus (absent in P. xibun sp. nov.). Antenna dark brown to black; postpedicel suboval, subtriangular or subrectangular; arista-like stylus two-segmented, shorter than eye height, first segment usually arched, second segment long, about 2–3X longer than first segment and with dense and short microtrichia (e.g. Figs 1E, 2E, 8E). Thorax. Mesonotum with 5 pairs of strong dorsocentral setae; acrostichals short, biseriate, ending at level of the fourth posterior dorsocentral seta (e.g. Figs 8B, 11B). Wing. Long and narrow; anal lobe barely developed; vein M 1 strongly bowed towards R 4+5, weakly to strongly concave posteriorly; vein M 1 ending before distal portion of wing apex; vein M 4 longer than dm-m (e.g. Figs 1I, 2F, 8F). Legs. Legs unmodified, only ventral surface of tarsus I covered with weak whitish pile (e.g., P. arcuatus). Femur I with anteroventral row of short setae increasing in length at apex; femur II with anteroventral row of setae, ending in 2–3 more conspicuous setae and with 1 strong anterior preapical seta at 5/6; femur III laterally compressed, with anteroventral and dorsal rows of setae, anteroventral row increasing in length towards apex, and 1 strong anterior preapical seta at 5/6.
Abdomen. Tergites 1–5 setose, tergite 6 either with short or long and strong lateral setae (e.g. Figs 1H, 8D, 9F, 11E) (bare in P. arcuatus (Fig. 2D)), segment 7 forming a long (usually as long as hypopygium) and well sclerotized peduncle; sternite 6 plate-like, weakly connected posteriorly to tergite 6 (e.g. Figs 3A, 9A, 12A). Hypopygium: Epandrium narrow, about 2.5–3X longer than high, with lateral ridge forming an acute apicoventral projection. Apicoventral epandrial lobe not developed, but recognizable by two apicoventral epandrial setae (e.g. Figs 3G, 9E, 12D); basal apicoventral epandrial seta usually longer than ventral lobe of surstylus. Ventral lobe of surstylus somewhat digitiform or L-shaped, weakly to strongly curved ventrally, with 1 stout modified apical seta (e.g. Figs 9C, 12D, 16D). Dorsal lobe of surstylus shorter than ventral lobe and weakly sclerotized, usually with strong setae at ventral and/or apical edges (e.g. Figs 3F, 9J, K, 12D). Phallus divided into two narrow and strong sclerotized arms, coated with a thin membrane, with small bumps or spinules at base of exposed part, apical part with dentiform or rounded processes (e.g. Figs 3D, 12F, 16E, 20E) (with fringe of spines in P. angustipennis Van Duzee (Fig. 9C, D)). Hypandrium as long as exposed part of phallus, strongly sclerotized, trough-shaped, with weak connection to epandrium basally, free laterally, apex bifurcate and weakly sclerotized (e.g. Figs 3E, 9I, 16G) (apex strongly sclerotized in P. xibun sp. nov. (Fig. 20F)), somewhat arrow-shaped, lateral margin usually with dentiform preapical processes, base of hypandrium projecting up inside epandrial capsule, cradling the phallus. Sperm pump short, well sclerotized, somewhat kidney-shaped, pipe-shaped or C-shaped, about 1/2 to 1/3 as long as ejaculatory apodeme (e.g. Figs 3D, 9C, 12E). Ejaculatory apodeme usually strongly sclerotized (weakly sclerotized in P. brooksi sp. nov. (Fig. 12E)), long and narrow, about 1/2 as long as epandrium and slightly widening apically (e.g. Figs 3D, 9C, 16E). Proctiger weakly sclerotized, dorsoventrally flattened (e.g. Figs 12E, 16E) (modified in an undivided proctiger brush in P. arcuatus (Fig. 3D)). Cercus short, suboval or drop-shaped, about 1/3 to 1/2 as long as epandrium, lacking basolateral tail (e.g. Figs 2D, 9G, 12B). Females. Similar to male in habitus and chaetotaxy, differing mainly by the face and clypeus wider (both wider than ocellar tubercle), with eyes almost parallel sided and the short postpedicel, about as long as wide (e.g. Figs 4B, C, 10B, C, 13B, C).
Included species. P. arcuatus (Loew, 1861), P. pumilio Loew, 1872 and the following newly ascribed species: Paraclius angusticauda Van Duzee, 1933, P. angustipennis Van Duzee, 1929, P. brooksi sp. nov., P. elongatus Van Duzee, 1930, and P. xibun sp. nov.
Remarks. Brooks (2005) was the first to mention the Paraclius arcuatus species-group (Paraclius sensu stricto) composed of the following species: Paraclius arcuatus, P. pumilio and “ Paraclius sp. 1 ”. However, after gathering information from descriptions, photos of types and identified material of nearly all New World Paraclius we found additional species that fit this group. The Paraclius arcuatus species-group is a small lineage whose monophyly is supported by the characters discussed below (see Discussion section), mainly by the male face narrowing below, clypeus short, about 1/4 as long as face, the absence of a developed apicoventral epandrial lobe, the acute apical ridge of epandrium and the trough-shaped hypandrium.
Distribution. The group is mostly restricted to Central and North America, with some species reaching the Caribbean Islands. The distribution range is from Northern USA to Costa Rica in Central America and the Caribbean islands of Cuba, Jamaica, Grenada, and Saint Vincent and the Grenadines, not reaching mainland South America (Figs 22, 23).
description: Published as part of Soares, Matheus M. M., Runyon, Justin B., Capellari, Renato S. & Ale-Rocha, Rosaly, 2023, Review of Paraclius arcuatus species-group (Diptera, Dolichopodidae) with description of two new species, pp. 151-182 in Zootaxa 5323 (2) on pages 152-153, DOI: 10.11646/zootaxa.5323.2.1, http://zenodo.org/record/8204101