ALBERT

Description: This study describes bioerosion traces ascribed to either predation or endo- and epibiont activity in twenty assemblages from the Mediterranean region and Paratethys, spanning in age from Eocene to Recent. Statistical analysis of the distribution of bioerosion traces among genera and assemblages revealed that there is higher drilling predation intensity on smaller species. Larger species seem to be primarily affected by non-drilling predators. Greatest variety in types of bioerosion could be related to species’ ecology and body size. Both major categories of bioerosion (etchings and traces of predatory activity) vary considerably among samples. Different genera show significant differences in the frequency of different bioerosion types. Shell size seems a major factor contributing to these differences.

Description: This paper describes a terebratelloid articulate brachiopod, Gyrothyris williamsi sp. nov., based on 95 specimens from seamounts on the Lord Howe Rise, Coral Sea, SW Pacific Ocean. The new species is attributed to Gyrothyris on the basis of (a) morphological and growth trajectory similarities; (b) phylogenetic analyses of an alignment of DNA sequence (∼2900-sites) obtained from nuclear-encoded small- and large-subunit ribosomal RNA genes (SSU and LSU); and (c) the presence of a distinctive, two-part deletion in the LSU gene. It is distinguished morphologically from Gyrothyris mawsoni and its subspecies by both internal and external morphology and by its isolated geographical distribution, which extends the patchy, known range of this genus to an area some 2000 km north of its previous northern limit around New Zealand. Phylogenetic analyses of the rDNAs and of mitochondrial cox1 gene sequences (663 sites) confirm previous indications that the New Zealand endemic terebratelloid genera form a clade (Neothyris (Calloria, Gyrothyris, Terebratella), but the position of Terebratella with respect to Calloria and Gyrothyris remains weakly established. These sequences disagree inexplicably about the closeness of the relationship between Neothyris parva and N. lenticularis. Analyses of the first sequences from Calloria variegata, a species restricted to the Hauraki Gulf, New Zealand, are consistent with the possibility that it originated locally, and recently, from C. inconspicua. Magellania venosa from S. America/Falklands joins with Antarctic Magellania fragilis and M. joubini to form an rDNA clade that excludes Terebratalia as the putative sister-group of the New Zealand terebratelloid clade. The cox1 (but not the rDNA) sequences of the New Zealand clade pass a test for clock-like rates of evolution, and maximum likelihood pairwise distances suggest that if genetic isolation between the ancestor of Antarctic Magellania and the last common ancestor of the New Zealand terebratelloid clade was initiated by separation of the Antarctic and New Zealand plates ∼90 Mya, isolation from M. venosa was initiated earlier, perhaps ∼145 Mya. However, in the simple phylogenetic reconstruction presented here from cox1 sequences, S. American and Antarctic Magellania spp. do not yield a well-supported clade, perhaps because of differences in base composition.