Determination of a new species of crayfish (Decapoda: Cambaridae) from the lower Tennessee River Drainage, USA.

Abstract

The crayfish genus Faxonius, formerly composed of surface-dwelling Orconectes, has over 95 species and subspecies. From these, no other species group has been the topic of more debate than the F. juvenilis complex (FJSC). As far back as 1885, Walter Faxon questioned the validity of species in FJSC due to similar character-states, leading to the composition of the group being up for debate for over 130 years. The FJSC is currently defined in Taylor, 2000 as all members of the former subgenus Procericambarus (genus Cambarus) east of the Mississippi River possessing a strong central project of the form I male gonopod, and a central projection that accounts for at least 35% of the total gonopod length. The most recent work on this taxonomic group was published in 2016 naming a new species, F. yanahlindus, from the lower Tennessee River drainage. However, there is another crayfish found in Weatherford Creek that we believe to be a new Faxonius species. We hypothesize F. sp. to be most closely related to F. yanahlindus due to the presence of the distomedial carpal spine, a character unique in the FJSC. F. sp. found in Weatherford Creek differs from F. yanahlindus in coloration and morphology. Preliminary analyses show that F. sp. is genetically distinct from F. yanahlindus. Our findings will be used to describe F. sp. from the lower Tennessee River drainage as a new species.