There were hundreds of these "bee beetles" darting around at mid-day in somewhat overcast-to-clear but relatively warm and calm weather. The habitat was rolling coastal prairie with a sandy substrate, within a mile of the Pacific to the west, and also equally close to Drake's Estero on the east.
These beetles really do
look and sound like bumble-bees as they fly past! This seemed quite a feat to me for beetles...which are so often such cumbersome flyers, holding out their elytra like ungainly wind baffles.
More posts from the population seen here on this date appear below:
I think it's clear these are Lichnanthe
and diligently tried to key them out using Carlson (1980)
...and I think what my photos here record from that day are two (of the three!) color forms of Lichnanthe rathvoni
. But I'm not very satisfied I was able to capture (or properly interpret) the key characters used in that reference. One useful item gleaned from the range maps and discussion in Carlson's paper is that only two species of Lichnanthe
are known from the Point Reyes area: L. rathvoni
and L. ursina
At any rate, here's a summary of the characters that seem relevant:
1) All my images here appear to be of males, as they have relatively long lamellae (= apical "club segments" of the antennae). In particular, the lamellae are longer than the funicle (= portion of antenna between the scape [= 1st segment] and the lamellae, or "club").
2) In all my images, I think
I see a (quite small) impunctate area on the posterio-lateral corners of the pronota which, according to the key in Carlson, would result in L. rathvoni
...as opposed to L. ursina
, which is described as having the posterio-lateral corners of the pronota entirely punctate.
3) The dorsal aspect diagrams for the pronota of L. rathvoni
and L. ursina
appear on pg. 187 of Carlson (1980). That of rathvoni
is smoothly convex along the posterior edge which agrees with my photos. (The posterior edge in ursina
is shown as slightly emarginate.)
4) Carlson uses the term "dihiscence" to refer to the angle and degree to which the elytra separate apically. (Coming from a botanical background, this seemed to me a strange use of that term, which refers to fruits or other structures opening along sutures in botany. But it's consistent with the definition given here
.) Comparing the elytra in the image of the "dark form" here with the diagrams for rathvoni
on pg. 188 of Carlson, it's hard for me to say which fits better. (But it seems to me the diagram for rathvoni
definitely fits better for the more sharply triangular separation in the "yellow form" in my other images.)