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Species Physocephala sagittaria

Physocephala sp? - Physocephala sagittaria Curated Specimen from CAS - Physocephala sagittaria - male Conopidae- Thick-headed flies, Physocephala sp - Physocephala sagittaria - male Double-keeled Fly - Physocephala sagittaria - female Mating Flies [=Physocephala?] ID Request - Physocephala sagittaria - male - female Physocephala sagittaria? - Physocephala sagittaria - male Physocephala - Physocephala sagittaria - male Fly - Physocephala sagittaria
Classification
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Diptera (Flies)
No Taxon ("Acalyptratae")
Superfamily Sciomyzoidea
Family Conopidae (Thick-headed Flies)
Subfamily Conopinae
Genus Physocephala
Species sagittaria (Physocephala sagittaria)
Synonyms and other taxonomic changes
Synonymy below from Camras (1957), hyperlinks go to original descriptions.
  Conops sagittaria Say, 1823, Jour. Acad. Nat. Philad., 3:83
  Conops aethiops Walker, 1849, List Dipt. Brit. Mus., part 3, pg 671
  Conops dimidiatus Walker, 1852, Dipt. Saundersiana., 4:254
  Conops genualis Loew, 1853, Neue Beitrage, 1:32 (see Williston's 1882 translation from Trans. Conn. Acad. Arts & Sci.)
  Conops castanopterus Loew, 1853, Neue Beitrage, 1:33 (see Williston's 1882 translation from Trans. Conn. Acad. Arts & Sci.)
  Conops ruficornis Van Duzee, 1934, Ann. Ent. Soc. Amer., 27:315
Identification
P. sagittaria is a variable species (see "Remarks" section below) with overall body color grading from dark brownish-black, to deep reddish with black dorsal markings. In each case, the first four or more abdominal segments have thin yellowish apical bands.
The most constant characters of the species are: discal cell dark; facial grooves dark; cheeks brown fore and aft, quadrate yellow "spot" filling middle; yellowish humeral markings present (dash-like and "waxy-dusted" = pollinose), rarely the dust-like pollinosity faint, revealing underlying red.
More variable characters are: vertex usually yellowish-brown to red, sometimes black; scutellum usually red, sometimes black; costal cell usually concolorous with adjacent cells, sometimes lighter brown or even partly hyaline.
Range
North Dakota e. to Massachusetts, and s. to New Mexico and Florida (1)
Remarks
This appears to be one of the most variable Physocephala species (along with P. marginata and P. texana).
There are (at least) two major color forms of P. sagittaria:
A dark form (black or dark brown) that occurs throughout the species range, and corresponds to Loew's Conops genualis (description here), seen in the thumbnails below:
         

And a ferruginous form (i.e. mostly red) occurring in the southeastern U.S. (sometimes mistaken for P. texana), corresponding to Loew's Conops castanopterus (description here) seen in these other thumbnails:
         
Other forms exist corresponding to various modalities associated with the six named entities (and their intermediates) which are synonymized under P. sagittaria.
See Also
P. marginata is separated from P. sagittaria based mainly on whether the discal cell is hyaline or infuscated, respectively. But sometimes there are intermediates, e.g. the discal cell of P. sagittaria may be patchily pale...or in P. marginata the discal cell may be darkened well within its edges. Parsons(1948) considered the two to be variants within a single species and referred both to P. marginata, whereas Camras(1957) found that in the vast majority of specimens the two were readily separable, and decided to maintain the two species as separate in his circumscription.
P. marginata (like P. sagittaria) has "dark" and "ferruginous" forms, as well as intermediate color forms.
Print References
Camras, S. and P. D. Hurd, Jr (1957). "The Conopid Flies of California (Diptera)(2)", Bull. Cal. Insect Survey Vol 6, No.2 (Full Text)
Camras, S. (1957). "A review of the New World Physocephala (Diptera: Conopidae)". Ann. Ent. Soc. Am. 50:213-218.
Camras, Sidney (1996). "New information on the New World Physocephala (Diptera: Conopidae)", Entomological News, 107(2): 104-112 (Full Text)
Parsons C.T. (1948). A classification of North American Conopidae. Ann. Ent. Soc. Am. 41: 223-246 (Full text)
Townsend, L. H. (1935). The mature larva and puparium of Physocephala sagittaria (Say) (Diptera, Conopidae). Psyche, 42: 142-148. (Full Text)
Internet References
MCZ Type image of Conops genualis, a synonym (for the "dark form") of P. sagittaria.
Works Cited
1.A Catalog of the Diptera of America North of Mexico
Alan Stone, et al. 1965. United States Department of Agriculture.
2.The Conopid Flies of California
Sidney Camras and Paul D. Hurd, Jr. 1957. University of California Press.