Nactus heteronotus (Boulenger, 1885)

Nactus heteronotus View in CoL group

This clade has a disjunct distribution spanning northern Australia, the southern coast of New Guinea and the northern coast of New Guinea. In Australia and northern New Guinea, we had little trouble matching lineages to names; lineages from southern New Guinea were much more problematic. Samples from the type locality of N. heteronotus on Yule Island ( cf. heteronotus 5) are genetically somewhat divergent from a population of small-bodied Nactus ( cf. heteronotus 2) that Zug (2020) assigned to this species from savannahs around Port Moresby. These Yule Island samples are genetically closer to samples from the Kikori and Purari River basins ( cf. heteronotus 3) that Zug assigned to N. papua . The holotype of N. heteronotus is believed to be immature, meaning it is difficult to determine what the typical adult size of the population it hails from is ( Zug, 2020). In addition, Nactus populations from Laronu ( cf. alotau ) that Zug ascribed to N. alotau (see below) fall into the N. heteronotus species group and are genetically highly divergent from other samples of N. alotau . Clearly resolving species boundaries and diversity within this group will take some work, but to stabilise the taxonomy of the group, we consider all these six lineages conspecific. Accordingly, we consider N. papua a synonym of N. heteronotus and apply the earlier name, N. heteronotus , to all populations of smaller-bodied Nactus (max SVL < 65 mm) in a well-supported and geographically cohesive clade occurring from Gulf Province, Central Province, and into southwestern Oro Province (including some that have been referred to as N. alotau ).