Cystisoma neptunus Guérin ­Méneville

Cystisoma neptunus Guérin­Méneville, 1842: 215 ­216, pl. 1, fig. 1.

The type seems to be lost. It is not in the ANSP, which holds most of the Guérin­Méneville collection (Zeidler 1997), and it is not present in the collections of the MNHN (checked personally by T. Laperousaz), or the BMNH.

In the past it has been considered a questionable synonym of C. pellucida (e.g. Vinogradov et al. 1982), but the antennae and uropods of C. pellucida are quite distinctive, and unlike that illustrated for C. neptunus by Guérin­Méneville (1842). The specimen illustrated by Guérin­Méneville appears to be male, as pereopod 7 would have differentiated at 80 mm if the specimen was female. The length of the antennae and pereopods resemble C. longipes (Bovallius, 1886), but in the absence of knowledge regarding the teeth on the mandible, this species cannot be determined with certainty.