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C. dorsata - dorsal - Castianeira dorsata - male

C. dorsata - dorsal - Castianeira dorsata - Male
Hornsby Bend, Austin, Travis County, Texas, USA
June 14, 2012
Size: 7.5mm
Castianeira dorsata. Det. J.T.Lapp 2013. Collected by myself, Joel Hallan, and Ian Wright

This spider readily keys to C. dorsata via Reiskind 1969. The male genital index (ratio of embolus length to full bulb length including embolus) is 28. The description for C. dorsata includes the words "an almost full, rectangular, orange ventral sclerite," which the live spider does not have. After much effort trying to find another species to fit this to, I realized that the key was using the colors of a preserved specimen. The colors change. I've included a ventral shot of the preserved specimen, which does have an orangish color.

The date given is the date collected as a penultimate male. The spider became an adult within a few days of August 1st. We also found a penultimate female only minutes and feet away from this specimen, which I also collected and raised. Here are photos of the adult and penultimate of that female. Notice how similar the penultimates are.

This is a new record for Texas, per Allen Dean's list. As of the Reiskind 1969 paper, there appear to only be a few records from far-south Arizona, as well as records in Mexico. Even if it's not C. dorsata, it's clearly in the "dorsata group" per Reiskind. Nothing in the dorsata group is reported for Texas, so it's still new for Texas.

Further supporting the likelihood that this is C. dorsata, BugGuide contains a number of photos of spiders that look just like mine -- immature and adult forms, male and female -- that are found in Pima County, Arizona, which is on the border with Mexico like the other Arizona counties where Reiskind reports C. dorsata to be found.

Images of this individual: tag all
C. dorsata - dorsal - Castianeira dorsata - male C. dorsata - side - Castianeira dorsata - male C. dorsata - ventral live - Castianeira dorsata - male C. dorsata - ventral in alcohol - Castianeira dorsata - male C. dorsata - ventral palp - Castianeira dorsata - male C. dorsata - palp tip - Castianeira dorsata - male C. dorsata - penultimate dorsal - Castianeira dorsata - male C. dorsata - penultimate side - Castianeira dorsata - male C. dorsata - penultimate angled - Castianeira dorsata - male C. dorsata - penultimate ventral - Castianeira dorsata - male

Allen Dean at TAMU looked at these two specimens (male and female) and confirmed that they are "probably" C. dorsata.

Reiskind's colors of limited value for live spiders
I'm inclined to disregard Reiskind's color pattern characterization for C. dorsata, regardless of whether this spider here is C. dorsata. Notice that the ventral sclerite of this specimen is black with a white patch in the live photo, yet the sclerite seems fully orange in the preserved photo. Reiskind says that the male C. dorsata has an orange ventral sclerite but no white on the abdomen. However, Reiskind was working with preserved specimens. Since we now see that black or white areas can turn (or appear) orange after preservation, it seems to me that much of Reiskind's color patterns go out the window, particularly for white and orange patterns, at least with respect to live photos, but perhaps also for recently preserved specimens.

Castianeira dorsata
Very impressive. It's wonderful to see both the juveniles and the adults. Great work!

I moved most of Jillian's images. I'd like your opinion on this one

These two spiders were a hugely lucky find. Both penultimates, one male and one female, same location and same time further suggesting that they're the same species. We're luckier still that we saw them and could catch them. These buggers are super-fast and they only stop when they think they're hidden. Photographing them in my bath tub was a huge pain in the tush. I could not keep the female in the tub. And without all this information together, connecting them to the Pima County spiders might have been less successful.

Moved from Spiders.

Moved from ID Request.

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