Acanthocnema rainierensis, Sinclair, 2025

Sinclair, Bradley J., 2025, Revision of the Nearctic species of Acanthocnema Becker, 1894 (Diptera: Scathophagidae), European Journal of Taxonomy 1026, pp. 304-337 : 320-323

Acanthocnema rainierensis sp. nov.

urn:lsid:zoobank.org:act:

Figs 35–40, 62

Diagnosis

This species is distinguished by the yellowish body, proepimeral seta present, fore femur with four long, spine-like posteroventral setae and distal row of strong posteroventral setae, wing with discal crossband and dark spot at apex of M 1, and crossvein dm-m not aligned with apex of M 4.

Etymology

The species is named after the type locality, Mt Rainier National Park.

Type material

Holotype

USA – Washington • ♂; “ MtRainier, Wn [ Washington ] / VanTrump Crk [ 46°47′34″ N, 121°46′33″ W] / Sep. 1, 1917 / A.L. Melander // ALMelander / Collection / 1961 // HOLOTYPE / Acanthocnema / rainierensis / Sinclair [red label]”; USNM.

Paratypes

USA – Washington • 1 ♀; same data as for holotype; USNM • 1 ♀; Mt Rainier, Longmire ; [ 46°44′56″ N, 121°48′51″ W]; 18 Jul. 1922; A.L. Melander leg.; USNM • 1 ♂; Mt Rainier NP, Wonderland Trail, Narada Falls to Cougar Rock ; 46°46′22.11″ N, 121°44′52.30″ W; 1317 m a.s.l.; 29 Jul. 2016; R.J. Pivar leg.; creek; CNC, CNC5288369 .

Description

Body yellowish laterally and brown dorsally ( Fig. 35), with dense white pruinescence. Body length: 4.4–5.0 mm; wing length: 4.4–4.7 mm.

Male

HEAD ( Fig. 35). Frontal vitta yellow to yellowish brown anteriorly, matt; fronto-orbital plate brown, with numerous dark setulae. Chaetotaxy: anterior orbital seta proclinate, posterior 2 orbital setae lateroclinate; 3 inclinate frontals; 1 ocellar, 1 inner vertical, 1 outer vertical; postocellar setae weak, divergent; row of dark postocular setae; 1 vibrissa, 1 strong subvibrissa. Gena silvery pruinescent, depth one-quarter eye height; postgenal setae white, soft, length shorter than width of postgena. Face, parafacial and occiput silvery pruinescent. Palpus yellowish white with white setae. Proboscis with broad, shiny prementum, with scattered white setae, shorter than width of prementum. Antenna dark, with inner face of pedicel and inner basal half of postpedicel yellow; postpedicel rounded apically, 2 × as long as broad. Arista pubescent on basal third and bare apically.

THORAX ( Fig. 35). Brown dorsally, broadly yellow laterally; greyish vitta along acrostichal series. Acrostichals biserial, short, slender; 1–2+3 dorsocentrals; 1+2 intra-alars; 1+1 supra-alars; 1 postpronotal; 2 notopleurals, 2 postalars; scutellum with pair of strong apical setae and pair of strong basal setae; scutellar disc with few scattered setulae. Proepisternal seta present. Proepimeral seta present. Anepisternum with dark setulae on posterior half and 1 long seta and several long thinner setae near posterior margin. Katepisternum with 1 strong, long seta in posterodorsal corner and numerous yellow setulae.

LEGS ( Fig. 36). Yellow. Fore femur with 4 posteroventral spine-like setae on basal half, longer than width of basalmost seta; row of strong posteroventral setae on distal half; distinct row of anteroventral setae, stronger near mid-length; 4 posterodorsal setae on apical half, shorter than width of femur. Fore tibia with ventral apical spur; 1 anterodorsal slightly proximal to mid-length, 1 posteroventral near mid-length and 1 preapical dorsal seta; biserial row of short spinules ventrally. Fore tarsomere 1 with dense mat of anterior setulae. Mid femur with 4 long posteroventral setae on basal half, several longer than width of femur; row of anteroventral setae on distal half, shorter than width of femur; row of 5–6 anterior setae; 1 preapical anterior seta and 1 posterior preapical seta. Mid tibia with 1 anterodorsal seta beyond mid-length and 1 preapical anterodorsal seta; 1 anteroventral seta and 1 posteroventral apical seta. Hind femur with row of 4–6 anterodorsal setae; 1–2 distal anteroventral setae. Hind tibia with 3 anterodorsal setae; 1 posterodorsal seta near mid-length; 1 dorsal preapical seta; 1 anteroventral apical seta.

WING ( Fig. 37). Infuscate, with discal crossband from costa to M 4 and dark spot at apex of M 1, veins black; crossvein dm-m not aligned with M 4; M 4 beyond cell dm weakened apically, reaching wing margin, more than one-half length of crossvein dm-m; CuA+CuP weakened but reaching wing margin. Calypteres and halter yellow.

ABDOMEN. Dark dorsally, similar to thorax, with greyish pruinescence; with long erect setae on tergite 2 anteriorly. Sternites 3 and 4 expanded laterally with elongate setae ( Fig. 38). Sternite 5 broadly expanded laterally with elongate setae, with pair of triangular lobes with narrow, incurved apex ( Fig. 38). Terminalia ( Figs 39–40): Epandrium rounded, narrow with short setae; prolonged ventrally beyond base of surstylus. Cercus short, apical margin rounded in lateral view; cerci closely approximated medially, with short apical setae. Surstylus digitiform; distal half expanded laterally, with wavy setae of various lengths, some longer than length of surstylus. Phallapodeme elongate, rod-shaped. Pregonite strongly recurved on distal half; apex tapered to rounded point with single short subapical seta. Postgonite gently arched with rounded apex. Ejaculatory apodeme flattened with expanded ejaculatory duct. Distiphallus narrow, tube-shaped with jagged inner margin.

Female

Similar to male except, abdomen darker, lacking long lateral setae on sternites 3 and 4; tergite 7 subtriangular, fused with sternite 7, dorsally tapered and medially divided; tergite 8 U-shaped, enclosing proctiger, narrowly divided medially, obliquely angled; sternite 8 divided into pair of tapered digitiform lobes, directed dorsally with pointed apex; epiproct and hypoproct small, triangular; cercus oval, thinly sclerotized. Three spermathecae tubular, narrow and recurved posteriorly into duct, expanded anteriorly.

Distribution

This species is currently known only from Mt Rainier National Park in the state of Washington, USA ( Fig. 62).