Webspinner - Oligotoma - BugGuide.Net

Moved

Moved from Webspinners. ID by Dean Rider - more than likely the Black webspinner, but not certain

… john and jane balaban, 8 June, 2009 - 10:30pm

Thanks, John, Jane, and Dean.

Glad to get a highly educated guess.

… Jim McClarin, 9 June, 2009 - 12:08am

Wow!

Just looking at the winged males that were already in the Guide, one would have had no idea how odd and unique webspinners really are. Thank you for filling in the blanks with these amazing images!

I'm no expert on insects, let alone webspinners, but using the same sources I used to ID "my" Oligotoma nigra males, I would suggest this is most likely a female of that species:

The world Embiidina checklist lists only Dactylocerca rubra for NM, but the article on The Embioptera of California (1957- PDF format) lists Oligotoma nigra's "Man-created New World distribution" as: "Warm regions of California, Nevada, Arizona,and Texas (one record). Probably also in Rio Grande Valley of New Mexico, northern Sonora and Baja California, Mexico."

The same article has the following key: Hind basitarsus with a medial, membranous sole-bladder in addition to the usual terminal terminal bladder (fig. 2). Parthenogenetic species Haploembia solieri (Rambur) Hind basitarsus without a medial sole-bladder (fig. 1). Bisexual species . . . . . . . . . . . . 2 Small species (adults less than 8.0 mm. in length). Juveniles pale reddish-brown; adult female brick-red; adult male red with terminalia and head black. Left cercus of male one-segmented, long arcuate (fig. 3) Chelicerca rubra (Ross) Larger species (adults at least 9.0 mm. in length. Juveniles pale tan; adult female blackish-brown; adult male uniformly medium to dark brown. Left cercus of male two-segmented, segments straight (fig.4) Oligotoma nigra Hagen

Two obvious hits against Dactylocerca are the large size of this specimen, and the pale tan color of your juvenile:
Unless there's some other species that the references missed, it has to be Oligotoma nigra. I wonder whether there are other authenticated sightings/collections of this species in NM, or whether you've provided the first proof.

… Chuck Entz, 29 December, 2005 - 1:41am

Male & Female Compared

I've compared this individual with the newly collected winged male here.

… Jim McClarin, 29 December, 2005 - 11:31am

ID of Male

Whatever species the male is, he's not Dactylocerca rubra- that species has the left cercus shorter than the right one, and curved inward. Haploembia solieri is represented (in California, anyway) only by parthenogenic females- though there are males in the native populations in Europe. To eliminate it using the key above, you'd have to take closeups of the hind legs showing their itty-bitty-teeny-tiny little footsies. :)

There's always the possibility that we're looking at another species not covered by the California publication, in which case it could be almost anything else: Las Cruces is very close to the border, so there's always the possibility of a mated female hitchhiking in from Mexico unobserved.

… Chuck Entz, 29 December, 2005 - 3:19pm

Yes,

that Mexican border is pretty porous! Know any Webspinner authorities we could show these pix to? I do mave a macroscope at home I might be able to shoot feet with if/when I get around to it.

… Jim McClarin, 30 December, 2005 - 9:13am

Webspinner Experts

The authority on webspinners is Edward Ross at the California Academy of Sciences. You can find his email address on the world checklist page.

… Chuck Entz, 30 December, 2005 - 11:36am

Great

I found more juveniles or females today that look way darker. We may be dealing with several species here.

… Jim McClarin, 30 December, 2005 - 12:38pm

And Wow! back to you Chuck.

Great detailed comment! I just found a winged one that looks much like your pix. I'll photograph it today. Maybe I should introduce it to the female and see if I can get some mating shots.

… Jim McClarin, 29 December, 2005 - 2:49am