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This series shows a specimen from the California Academy of Sciences identified simply as "Tenthredomyia
" on the label data. Indeed, this goes clearly to Tenthredomyia
using the "Key to genera of Cerioidinae
" from Shannon(1927): based on the elongate antennifer and virtually non-constricted 2nd abdominal segment (see 5th image of the series
). Note that the genus name Tenthredomyia
is a prior synonym for the current genus name of Ceriana
...and, accordingly, this keys to Ceriana
using the more recent CJAI "Key to the Genera of Nearctic Syrphidae"
In the collage above, the specimen is shown in lateral view...together with various key characters indicated in green, and the "Key to Species of American Tenthredomyia
" from Shannon(1925) inset at the bottom. One can easily check that key leads unequivocally to T. anchoralis
(Coquillett). Note that Shannon erroneously added an "h" in his spelling of the epithet there...Coquillett's spelling (and that of others) is ancoralis
This specimen also goes to "Cerioides" ancoralis
using the key in Curran(1924)
, and is in excellent agreement with nearly all of Curran's detailed description thereof
...except for the absence here of the pollinose areas he described on the 4th (and less so 3rd) segment(s) in his paragraph on the abdomen (below the middle of pg. 38). Despite the absence of those pollinose markings, the ID seems bolstered by two diagnostic characters Curran emphasized at the outset of his discussion of ancoralis
: 1) "face with a small but conspicuous tubercle just above the oral margin" (dipicted in his Fig. 11 here
); and 2) "first abdominal segment with a peculiar lobe at the basal angles" (see 4th image of series
). Note also that the largely dark femora here are in accord with Curran's comments regarding leg color of the male
(near the bottom of pg. 38). This is a male, from the contiguous eyes at the vertex.
Coquillet's original 1902 description can be read here
, under the name Sphyximorpha ancoralis
. Note that, again beyond the absence of gray pollinosity on the 4th abdominal segment, the only other discrepancy between this specimen and Coquillett's description is his mention of a "small" yellow spot on the "lower part of pteropleura, sometimes very indistinct". On the other hand, Shannon's key expressly indicates that, in ancoralis
, the pleura have yellow spots only on the meso- and sterno-pleura. So I'm thinking the "sometimes very indistinct" qualifier Coquillett used in describing the pteropleural spot may allow for the 'absence' thereof. Indeed, there is no pteropleural spot in this lateral paratype image of ancoralis
(from this web page
...which also provides dorsal
images). In contrast there is a conspicuous pteropleural spot in this curated image identified as Ceriana ancoralis
. Note that neither of the two preceding curated ancoralis
specimens display the pollinosity on the 4th tergite that was mentioned by both Coquillett and Curran. As always, I wonder about the degree of intraspecies variation for many characters. As another such instance, note also that the supra-alar vitulla in the CAS specimen are much less conspicuously well-defined than they are in the hyperlinked paratype images.
Coquillett, Curran, and Shannon all indicated their specimens came from New Mexico...the location here is just west of New Mexico.
Finally, while the catalog of Stone et al(1)
(1965) listed Tenthredomyia ancoralis
as a synonym under T. tridens
, note that it's listed as a separate species in the relatively recent (2013) CJAI treatment of nearctic Ceriana here
Note on Nomenclature & Etymology: The old genus name Tenthredomyia is currently a junior synonym of Ceriana (sensu stricto)...or Ceriana (Ceriana) for those who follow the "subgenus approach" to circumscribing subtaxa of the tribe Cerioidini. [There are currently two nomenclatural schemes in use for referring to the traditional groupings within the tribe Cerioidini. Unfortunately, this results in much confusion in the interpretation of (binomial) names among those not familiar with the situation. For more on this, see the last five paragraphs of my (long!) iNaturalist comment here...or the remarks beginning at the 4th paragraph of my (again long) comment under this Flickr post of Sphiximorpha roederi.]
Shannon's name Tenthredomyia is a compound name formed from the Greek roots: "Tenthredo- = a kind of wasp" and "-myia = fly". It presumably refers to the un-constricted waist of these cerioidines, in analogy with wasps of the genus Tenthredo...which are among the "common sawflies" of the Symphyta. All other cerioidine genera have constricted waists and thus better mimic other (aculeate) wasps.