Key to the Neotropical Eristalis

Here is a key to the Eristalis of the Neotropical region.

There is an excellent paper on 'The Eristalis Flower Flies of the Americas South of the United States' by F.C. Thompson. This covers all the species here, and includes a very useful key, as well as full descriptions of all the species. Almost all of my information comes from this paper. The Thompson key however includes some clauses not well tailored to photographic ID, and also includes a few Palpada species.

The advantages of doing another key are partly the opportunity to tailor it towards photographs, partly for accessibility, and partly as a consolidation of learning exercise for myself. The Neotropical Eristalis are mostly quite visually distinctive, and it is not necessary to resort to clauses such as 'aristae plumose or bare'.

I'm not quite covering the same area as the Thompson paper. The Mexican states bordering the USA can see species that are regarded as Nearctic: So Thompson includes E stipator, but E arbustorum is also recorded on iNat from those northern states, and there is the obvious potential for other species such as E hirta to cross the border. For that reason I'm not including the very North of Mexico: Species covered by this key are alleni, bellardii, bogotensis, circe, croceimaculata, gatesi, persa and tenax.

For the Nearctic Eristalis (including the northernmost states of Mexico) see the excellent key by @edanko and @zdanko.

The greatest difficulty in identifying Eristalis in this region is actually confusion with some of the many Palpada species. Bolder markings on the scutum, a bright scutellum, brighter markings generally, and thickened hind legs are all indications that you may in fact have a Palpada.

Posted by matthewvosper matthewvosper, 31 December, 2021 11:29



Posted by zdanko about 1 year ago (Flag)

Note: Your link to Thompson's paper just goes to this journal post.

Posted by zdanko about 1 year ago (Flag)

Thanks! I've corrected the link. It was great to get such a flood of notifications this afternoon - good work! Incidentally, there's more to come on Eristalis - I'd hoped to get further over Christmas, so it might be a little while now, but other parts of the world are on their way (obviously I won't be duplicating your work in the Nearctic!)

Posted by matthewvosper about 1 year ago (Flag)

That sounds amazing; thank you for all of your work going through the Nearctic Eristalis, also.

P.S. do you have agreeing notifications on?

Posted by zdanko about 1 year ago (Flag)

Yes - I still get notifications for everything. Generally I hover over each one and if it's research grade I normally ignore it, if not I check to see If I've been disagreed with.

Posted by matthewvosper about 1 year ago (Flag)

I think if you include an Identify Link on the first slide that would be helpful.

Posted by zdanko about 1 year ago (Flag)

@zdanko I have added a link

Posted by matthewvosper about 1 year ago (Flag)

Great, thanks!

Posted by zdanko about 1 year ago (Flag)

There seem to be a few observations cropping up off North American coasts which are obviously caught by the boundaries of 'North America', but not excluded by the boundaries of e.g. 'Not Canada'. (I basically did 'North and South America, excluding Canada, USA, Greenland, and some northern Mexican States')

Posted by matthewvosper about 1 year ago (Flag)

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