This appears to be an anomalous Timema female.

The ventral aspect of the terminalia seen here appears quite different from the norm for female Timema...in that there are three (rather than one) large, overlapping, and roughly distally-triangular structures.

From left to right: the first such structure is the subgenital plate, which appears as a single, somewhat-oval, undivided sclerite here. But the two remaining and more distal, long-triangular structures seem quite unusual to me. They appear to be divided mesially into two longitudinal, reflectionally-symmetric halves that are connivent (or fused?). Very strange!

For comparison with a more typical female, see the thumbnail images below showing: 1) the ventral shot here; and 2) the other female Martin posted from the McCullough Range just southeast of Las Vegas:

      1)
      2)

For context...as far as functionality goes, I believe the female's subgenital plate protects her internal genitalia. It is lifted and held out of the way during copulation...as illustrated in the two (clickable) thumbnail images below:

           

...which come from Ken-ichi Ueda's iNat post here.

And the female's paddle-like lateral cerci are thought to be used, directly after egg-laying, to manipulate the egg by rolling it...together with a mixture of soil & the mother's feces...into a ball which is then placed in the soil. It's thought this is done to provide crypsis, reduce desiccation-stress on the egg, and perhaps transmit potential gut-flora symbionts for the future foliage-feeding larvae.

But it's a mystery to me what the origin and/or function may be for the two additional (and apparently anomalous) "triangular structures" in Martin's ventral image here? Perhaps one (or both) those two distal structures are normally shorter, and mostly hidden under the subgenital plate?