Abstract
A new cheilostome bryozoan genus, Powellitheca gen. nov., is erected here for three species from New Zealand, one of which has been previously assigned to Emballotheca Levinsen, 1909, but which differ significantly from the Australian type species of Emballotheca , E. quadrata (MacGillivray, 1880). Notably, whereas Emballotheca has a cormidial orifice (i.e., formed by numerous neighbouring zooids), and lepralielliform ooecia, the orifice of Powellitheca gen. nov. is formed by single zooids and ooecia are of the microporelliform type. The introduction of a new family, Powellithecidae fam. nov., becomes necessary because of the nonconformity of Powellitheca gen. nov. with other known families having microporelliform ooecia. In addition to the Recent type species Powellitheca terranovae gen. et sp. nov., one other new Recent species, P. labiosa gen. et sp. nov., and a Plio-Pleistocene fossil species, Monoporella waipukurensis Waters, 1887, are assigned to the new genus.
Highlights
Current research focusing on Plio-Pleistocene bryozoans from the Wanganui Basin has prompted the re-evaluation of a common cheilostome usually known as Emballotheca waipukurensis (Waters, 1887), which was originally described from Waipukurau Gorge in Hawkes Bay
The autozooidal orifice in E. quadrata is cormidial, while the ooecium is of the lepralielliform type, with an uncalcified endooecium and a calcified ectooecium, covered by the sutured secondary calcification formed by several zooids distal and distolateral of the fertile zooid
Restudy of Recent material from New Zealand previously identified as Emballotheca waipukurensis shows that it too differs from the Australian type species of Emballotheca and, close to the fossils from New Zealand, differs in several respects, warranting its recognition as a new species
Summary
Since its first description by Waters (1887) as Monoporella waipukurensis Waters, 1887, the common New Zealand Plio-Pleistocene species currently known as Emballotheca waipukurensis has causedEuropean Journal of Taxonomy 207: 1–17 (2016)problems for taxonomists, who have placed it in various genera, always with a degree of uncertainty. Brown (1952) excluded the species from Monoporella Hincks, 1881, as defined by Harmer (1926), but had difficulties in choosing an alternative genus, assigning it to “Hippoporina?” Neviani, 1895, pending the availability of better material to confirm his identification. Powell (1967) found, for the first time, several infertile specimens of what seemed to be the same species in Recent material obtained by the ‘Terra Nova’ Expedition in 1910. Powell (1967) found, for the first time, several infertile specimens of what seemed to be the same species in Recent material obtained by the ‘Terra Nova’ Expedition in 1910. He discussed Brown’s tentative assignment of M. waipukurensis to Hippoporina, noting that the dimorphic orifices, gigantic ooecia and randomly occurring lateral avicularia were features associated with Emballotheca Levinsen, 1909. Images obtained by Scanning Electron Microscopy (SEM) of a Recent specimen of Emballotheca quadrata in the Zoological Collection of the Natural History Museum, London (NHMUK) have allowed us to investigate further the differences between E. quadrata and ostensibly congeneric species from New Zealand, leading to the introduction of the new genus, Powellitheca gen. As Powellitheca gen. nov. does not conform to any of the other five families with microporelliform ooecial structure, the new family Powellithecidae fam. nov. is introduced here
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