Bacchini (in development)
Authors: Even Dankowicz
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Bacchini
| | diagnosis |
Baccha | widespread | |
Leucopodella marmorata | UT, AZ records | |
Melanostoma mellinum | widespread | can be separated from other genera by abdominal markings: males with paired long subrectangular orange markings on T2-4, females with paired markings on T2-4 with margins anterior transverse, medial longitudinal, and posterolateral oblique. |
Platycheirus | widespread | |
Pyrophaena | | |
Xanthandrus mexicanus | potentially from AZ to TX | abdomen black with large yellow markings on T3-4; larger and more robust than Melanostoma or Platycheirus |
Males holoptic
Baccha
….
| | |
B. cognata | widespread | pollinose female ocellar triangle |
B. elongata | Alaska, NWT, Yukon | shiny female ocellar triangle |
Leucopodella marmorata
….
Melanostoma mellinum
Unlike Platycheirus, males have square spots on abdomen without expanded fore tibiae or basitarsus. Females and dark males are harder to tell apart in a simple description.
Unlike some Platycheirus, Melanostoma always have a relatively unprotruding face with a small tubercle, and have a scutum that is proportionately smaller, shinier and more brownish metallic than most Platycheirus spp; also seemingly with narrower abdomen base
Platycheirus
70+ Nearctic species, most impossible to ID without microscopic characters. Andrew etal 2016 has key on p18, p26 for females
P. quadratus - male with large orange spots filling up most of abdomen, orange legs, and diagnostically with middle tibia evenly expanded and flattened over much of its length (widespread)
P. obscurus - metallic dark grey, rippled, pruinose, protruding face, with lower edge of face extending anterior as far as tubercle (Eastern)
P. confusus, metallic dark grey, rippled, pruinose, protruding face, with tubercle extending anterior past lower edge of face (widespread; this diagnosis is only differential east of the rockies)
P. trichopus - Face with distinct lower anterior margin, with transverse ripples, abdomen with spots ; lower edge of face extending anterior slightly past tubercle (west of rockies)
P. stegnus - Face with distinct lower anterior margin, entirely silvery pollinose with large dark punctures, except for smooth dark black tubercle (Western)
Platycheirus
P. nearcticus - male with fore basitarsus expanded with anterior keel, fore tibia unexpanded except at apex, posterior fore femur with many flattened black setae (Northeastern diagnosis)
P. scutatus - male with orange spots, posterior profemur with two dark tufts, protibia not strongly expanded, probasitarsus about 6x longer than subsequent segment (Northeastern diagnosis)
Pyrophaena
….
abdomen relatively wide
| | |
Northern US/Canada | T2-4 irregularly and confluently orange, otherwise abdomen black; male with expanded fore and middle basitarsus | |
Northern US/Canada | male T3-4, female irregularly T2-4, with paired spots sometimes confluent, largest on T3, abdomen otherwise black; male with unmodified tarsi |
Xanthandrus mexicanus
….
Sources