Bibio velcidus Hardy 1937

Bibio velcidus Hardy, 1937 (Fig. 3) Type material examined. Paratypes: CANADA: Ontario: Low Bush, Lake Abitibi, 12 June 1925, N.K. Bigelow, 3 males (BYUC); New Brunswick: Fredericton, 30 May 1931, R.P. Gorham, 1 male (BYUC) [see “Comments” below concerning this specimen]. Other material examined. CANADA: New Brunswick: Sunbury Co., Oromocto River, Hwy 101, Tracy, 25 June 1993, Baumann & Kondratieff, 1 male (BYUC); Quebec: Riviere aux Pins, Hwy 385, N Forestville, 15 June 1997, Baumann & Kondratieff, 3 males (BYUC), 3 males (SFC). Comments. Bibio velcidus Hardy has not been reported in the literature since its original description in 1937 (Hardy 1937). It was described from two sites in southeastern Canada; Low Bush, Ontario and Fredericton, New Brunswick with the type locality at Low Bush. Hardy (1937) listed the holotype as being deposited in the CNCI, but it could not be located there (SF pers. comm. with Brad Sinclair, March 2023). However, four paratype specimens, including three specimens from the type locality at Low Bush, were found at the BYUC and form the basis of this study of the species. The four paratypes were found to represent more than one species. The specimen from New Brunswick represented an undersized (wing length about 5 mm), but otherwise typical, specimen of B. vestitus Walker; this specimen differed notably from the remaining 3 paratypes by the longer fore tibial spur (about 4/5 length of spine), posterior wing veins unpigmented, very long and slender hind basitarsus, and different male terminalia. The male terminalia matched well with a more typically-sized specimen of this species from New York (SFC). The remaining 3 paratype specimens from Low Bush can be characterized as follows: fore tibial spur ranging from a little over 1/2–3/4 the length of the spine, wing length about 5.5 mm (n = 3), posterior veins pigmented and distinctly darker than the hyaline membrane, pterostigma pigmented, r-m subequal to slightly shorter than the base of Rs, hind legs with basal 1/3 of hind femur orangish with remainder brown, hind tibia and tarsi brownish with an orange tint (but tibia and tarsi appear paler overall than brown part of femur, especially when backlit), hind basitarsus relatively slender and about 4–4.5x as long as wide, hind tibial spurs apically acute, sensilla on inner surface of hind tibia 33–45 (n = 5 tibiae examined), antennal flagellum apparently with nine segments, mesonotal pile mostly dark with some pale pile more laterally, and male epandrium and gonostylus as in B. similis (see Fitzgerald 1997b, Figs. 7 & 10). No structural differences could be found to distinguish the Low Bush specimens from the western species B. similis James with the exception that the 3 male B. similis available for direct comparison (Colorado & Utah; SFC) were larger in size (wing length 6–7 mm) and the Low Bush specimens all have the basal 1/3 of the hind femur orange (Fig. 3) while this was not true of the B. similis specimens studied. Aside from these two characters, the Low Bush specimens fit well with the characterization of B. similis provided by Fitzgerald (1997b) including the structure of the epandrium and gonostylus of the male terminalia which had not been previously studied in B. velcidus; illustrations of B. similis terminalia can be found in Fitzgerald (1997b, Figs. 7 & 10). Seven additional specimens from two other sites in southeastern Canada (listed under “Other material examined” above) were found to be conspecific with the Low Bush paratypes. Intraspecific variation in this additional material included the hind tibia of one specimen being nearly orange (lacking brown tint) and wing length from about 5–6 mm in length (both slightly smaller and larger than specimens from the type series). In summary, the primary difference between the B. velcidus specimens and the B. similis specimens available for study were the wing length (5–6 mm vs 6–7 mm respectively) and that B. velcidus consistently had the basal 1/3 of the hind femur orange. Whether these differences are meaningful with respect to species boundaries remains an open question. Neither B. velcidus nor B. similis are commonly collected and the intraspecific variation of both the wing length and leg color remain understudied. The wing length difference seems weak evidence when considering that commonly collected and studied species such as B. albipennis Say can have wing length variation from 5.25–8 mm in length, yet average size is often useful in helping to recognize many species. Leg coloration is known to be variable in many Bibio species, but B. velcidus specimens consistently had the basal 1/3 of the hind femur orangish with remainder brown while the intraspecific variation of the leg color of B. similis discussed by Fitzgerald (1997b) does not mention this aspect, only stating that “legs range in color from black to dark brown to the femora blackish and the tibia and tarsi brown orange.” At present, B. similis and B. velcidus also appear to be allopatric; specimens of B. similis reported as far east as western South Dakota (Fitzgerald 1997b) and specimens of B. velcidus as far west as eastern Ontario. Whether they are truly allopatric or if this is just a function of collecting remains unclear. Further study seems warranted before the status of B. velcidus can be further addressed, but it is best treated as a distinct taxon until more data suggests otherwise.

Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.