Acerocnema rufula
Creators: name: Chagnon, Marie-Eve
name: Sinclair, Bradley J.
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Scathophagidae
Acerocnema
Acerocnema rufula

description: Acerocnema rufula (Curran, 1927)
(Figs 5, 6, 12, 17, 21, 25)
Cordylurella rufula Curran, 1927: 257. Type locality: Aylmer, Québec, Canada.
Cordylurella rufula: Vockeroth, 1965: 836.
Acerocnema rufula: Vockeroth, 1987: 1089 and 1093 (new combination).
Type material examined. HOLOTYPE ♀ labelled: “Aylmer, Que. [45°24′00″N 75°51′00″W]/ 4.VII.1924 / C.H. Curran ”; “ IDEMA / illustration”; “ Acerocnema / rufula/ det. M.-E. Chagnon 2018”; “ Cordylurella / Type/ rufula ♀ / Curran/ No. 2610 [red label]”; “ CNC/ 1589604 ” (CNC).
Additional material examined. CANADA. Ontario: 7 mi E Griffith [45°14′38.5″N 77°09′58.7″W], 8.vii.1989, B.E. Cooper (1♂, CNC); same data except, 16.vii.1989 (1♀, 1♂, CNC); same data except, 14.vii.1990 (4♀, CNC). Quebec: King Mountain, Old Chelsea [Gatineau] [45°32′32.6″N 75°52′05.8″W], 26.v.1963, J.G. Chillcott (1♀, CNC).
Diagnosis. This species is distinguished by its shiny yellow colouration, dark setae and narrow fascia along the posterior margin of the abdominal tergites.
Redescription. Male. Body primary colour yellow; pleura yellow; scutum yellow; entire body shiny. Setae on head black.
Head with face and gena yellow; genal width 1/3 eye height; postgena yellow; postocellar triangle brown. Frontal vitta dark yellow/brown; fronto-orbital plate dark yellow; parafacial yellow. Fronto-orbital plate with 4 inclinate frontal setae, 1 proclinate and 2 lateroclinate orbital setae, 1 pair of long lateroclinate ocellar setae, 1 pair of short, erect postocellar setae, 1 long, inclinate inner vertical seta, 1 lateroclinate outer vertical seta, shorter in length than inner vertical seta. Vibrissa strong, with 6 variably lengthened subvibrissal setae, none subequal to vibrissa, all subvibrissal yellow. Antenna with postpedicel black, about five times as long as pedicel; scape and pedicel black; arista black, pubescent and same length as dorsal surface of postpedicel. Palpus yellow with clear setae apically.
Thorax with scutal setae black; acrostichal setae biserial, finer than dorsocentrals, but distinct; 2 presutural and 3 postsutural dorsocentral setae, with smaller setulae between; 2 posterior postpronotal setae; 2 presutural intra-alar setae; 2 notopleural setae; 2 postsutural intra-alar setae; 1 postsutural supra-alar seta; 2 postalar setae; 2 pairs of scutellar setae. Pleura with 1 yellow proepisternal seta; 1 yellow proepimeral seta; 3 posterior anepisternal setae and several long anepisternal setulae, all yellow; 1 yellow, posterodorsal katepisternal setae; anterior half of anepisternum and anepimeron without setulae; katepisternum with setulae ventrally.
Wings (length 2.8–3.2 mm) clear, lightly infuscate, R 1 bare; CuA+CuP ending before wing margin. Halter yellow to white.
Legs entirely yellow. Setae on legs black. Fore femur with white ventral pile. Fore tibia with 1 mid dorsal seta. Mid femur with white ventral pile and 2 dorsal setae on apical 1/4. Mid tibia with 4 dorsal setae along dorsal surface. Hind femur with white ventral pile. Hind tibia with 4 dorsal setae along dorsal surface. Tarsi yellow with ventral pile.
Abdominal tergites yellow, except tergite 5 and epandrium black. Abdominal tergites with black setulae over surface.Abdominal tergites yellow. Sternite 5 Y-shaped, large and yellow, lobes triangular, broadly divergent, closely approximated medially; lobes with scattered stout setae (Fig. 12).
Terminalia (Figs 5, 6) with surstylus yellow; cercus yellow; hypandrium yellow. Epandrium on dorsal surface of abdomen, surstylus, cercus and tergite 5 all jutting out from ventral surface of abdomen. Surstylus long and slender, apical third curved ventrally, with short apical setae. Cercus small, composed of two sclerotized sections connected via membranes; dorsal section rectangular, with cluster of very long setae over surface (nearly subequal to length of surstylus), extended ventrally; ventral section in lateral view forming two sclerotized plates, one directly below dorsal section, bearing dense short setae on inner face and other extending ventrally as digitiform process. Pregonite with rectangular base and short forked apex; anterior fork triangular; posterior fork narrower, arched with 2 long, strong setae apically; setae extend anteriorly, 3 times length of pregonite. Postgonite digitiform, rather uniformly slim and gently curved anteriorly; longer than pregonite. Epiphallus similar shape and length to postgonite.
Female. Very similar to male; terminalia as in generic diagnosis.
Distribution. This species is currently known from a small region in eastern Ontario and western Quebec (Fig. 25).
Remarks. In the key to genera, Vockeroth (1987) stated that there were two species of the genus in North America, but he did not specifically list them. However, A. rufula was identified as one of the two species in a figure caption (Vockeroth 1987, fig. 17). Because this species was named in the Manual of Nearctic Diptera, we consider this to constitute the formal transfer of rufula to the genus Acerocnema.
description: Published as part of Chagnon, Marie-Eve & Sinclair, Bradley J., 2021, Revision of Nearctic species of Acerocnema Becker (Diptera: Scathophagidae), pp. 523-539 in Zootaxa 4952 (3) on pages 529-530, DOI: 10.11646/zootaxa.4952.3.5, http://zenodo.org/record/4690611