Rhingia rostrata I think

Geoff F · #1 (**permalink**) 01-06-2011, 06:24 PM

We were discussing the differences between R. campestris and the uncommon variation R. rostrata.

Here is what I think is R. rostrata, but I am willing to reconsider.

31/05/11 S. Devon wood near the sea.

and for comparison, R. campestris from the same location and on the same day.

JRsbugs · #2 (**permalink**) 01-06-2011, 07:06 PM

The thorax does look mostly dusted.

The abdomen does look a little dark on the side margins in the front view, although there's not much I think that is iffy.

The arista should be bare for rostrata, even though it looks bare campestris only has short hairs and photos don't always show them.

For rostrata the 3rd antennal segment should be as long as wide.. not really possible to say.

The real stumper here is the snout.. it looks to me to be too chunky, and longer than the diameter of an eye where for rostrata it should be as long as the diameter of an eye and hardly curved.

These are really difficult from photos, I have two angles of one from last year taken the day before the one I linked to diptera.info on the other thread. The abdomen has dark sides, and from behind looks to have little thorax dusting. From a slightly underneath side view the thorax looks well dusted and the snout looks more like the shape of rostrata.

Geoff F · #3 (**permalink**) 01-06-2011, 07:20 PM

Thanks. I will try to find the one that Roger confirmed for me last year.

Stubbs mentions that there can be some dark hair towards the edge of the tergites but he doesn't give any other subtle hints except about the short hairs on the thorax of females.

Geoff F · #4 (**permalink**) 02-06-2011, 07:37 PM

Looking at this one beside an image of R. campestris, the thorax does seem to have a bit of a bluish tint. A tip from Roger last year.

So I think I will label it as possible R. rostrata for now.

Time is a bit short for now as I am still finding more oddities to ponder.

Today produced a slightly different variation on what must be Chrysotoxum elegans, I think. This year, in a couple of locations, I am finding one or two a day.

And what I think must be Chrysotoxum bicinctum which is another newcomer for me.