Mystivagor Iredale, 1944: 317

Mystivagor Iredale, 1944: 317 View in CoL . Type species Mystivagor mastersi Iredale, 1944 by monotypy. Masculine. Syn nov.

Remarks

We follow Smith (1992) in synonymizing Howeinsulea , Deceptrena , Ballena , and Lidgbirdia . In addition, we synonymize Mystivagor based on molecular phylogenetics. Pseudocharopa is re-described to capture its changed species composition.

Pseudocharopa differs from Goweroconcha in its relatively large shell with reduced whorls, patterned with zigzagging flammulations, with either a supraperipheral sulcus or whorls flattened above the periphery. All species have shown a strong decline in numbers since they were first described, with one presumed extinct ( P. exquisita ) and three listed as Critically Endangered ( P. ledgbirdi , P. mastersi , P. whiteleggei ). The final species, P. balli , has demonstrated a sharp decline since the introduction of rats and would also be eligible for listing but has been considered a synonym of P. ledgbirdi for many years.

Members of this genus may be more vulnerable to disturbance than Goweroconcha . This could be due to their generally larger size, making them more attractive to rats; however, even the smaller members of the genus are affected. All Pseudocharopa species are endemic to the upper slopes and summits of the southern mountains, which are experiencing impacts from climate change. However, the summit species belonging to Goweroconcha do not appear to be similarly affected. It may be that Pseudocharopa has a lower birth rate and cannot replace its population as quickly, making it more susceptible to predation. In the larger species, P. whiteleggei and P. balli , adult shells of living specimens are extremely worn, perhaps indicating that these species grow slowly and live to an advanced age compared to other groups.