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.