Ooperipatellus nickmayeri

Ooperipatellus nickmayeri is a species of oviparous velvet worm in the family Peripatopsidae. This species is larger than any other in the genus Ooperipatellus. With a body size exceeding 60 mm in females and 30 mm in males, these velvet worms can be more than twice as long as other species of this genus.

Discovery
This species was first described by the biologists Ivo de Sena Oliveira and Georg Mayer in 2017 based on ten specimens collected from rotting logs and leaf litter in a small fragment of forest near the Lyell Highway in Tasmania. These specimens include a male holotype, three female paratypes, and six other specimens (five females and one male). The authors of the original description named this species for the six-year old son (Nick Mayer) of one of the authors, who suggested a stop along the road during which the authors discovered this species in 2013. The holotype is deposited in the Queen Victoria Museum and Art Gallery in Launceston, Tasmania.

Description
These velvet worms have 14 pairs of legs in both sexes, with the last pair reduced in size. Notwithstanding the large body size, which distinguishes this species from others in its genus, this species exhibits many of the features that characterize this genus, including oviparous reproduction, 14 leg pairs in each sex, females with a well-developed ovipositor, males with a cruciform gonopore, and the absence of any modified head papillae or head organ. Molecular phylogenetic analysis confirms the placement of this species in the genus Ooperipatellus.

This species also exhibits several features aside from its large size that help distinguish these velvet worms from other species in this genus. For example, these velvet worms vary in color from blue to predominantly orange-brown, with a light blue ventral surface, and their antennae feature a distinctive pattern of tan or orange bands on the antennal rings. Furthermore, the dorsal integument features dermal papillae arranged into 12 complete plicae per segment. Finally, karyological analysis reveals a distinct karyotype for this species, with a heteromorphic pair of sex chromosomes (XY) and the greatest number of chromosomes (2n = 50 XY) reported to date for a species in the family Peripatopsidae.