Ebiscothyris, Bitner & Cohen, 2015

Bitner, Maria Aleksandra & Cohen, Bernard L., 2015, Congruence and conflict: case studies of morphotaxonomy versus rDNA gene tree phylogeny among articulate brachiopods (Brachiopoda: Rhynchonelliformea), with description of a new genus, Zoological Journal of the Linnean Society 173 (2), pp. 486-504 : 496

EBISCOTHYRIS GEN. NOV.

Ebiscothyris bellonensis gen. et sp. nov. was collected in the Coral Sea, where the molluscan fauna is characterized by high endemism ( Kantor & Bouchet, 2007; Bouchet et al., 2008), and has not been reported elsewhere. A terebratelloid articulate brachiopod, Gyrothyris , also occurs in the Coral Sea but has a wider distribution, being known also from around New Zealand ( Lüter, 2008; MacFarlan et al., 2009). The gene tree ( Fig. 3 ) shows E. bellonensis gen. et sp. nov. to be sister to Kanakythyris pachyrhynchos Laurin, 1997 , which is known only from New Caledonia, the Loyalty Islands, and the Norfolk Ridge ( Laurin, 1997; Bitner, 2009), localities further from the Coral Sea than the expect- ed dispersal range of lecithotrophic terebratulide larvae. These taxa differ substantially in morphology: in Kanakythyris the beak is incurved with a very small foramen, whereas the loop has a strong, sharp median fold on the transverse band, forming a narrow ridge. Their disjunct distributions suggest that Ebiscothyris gen. nov. and Kanakythyris may have differentiated in place, descending from a formerly more widespread common ancestor.

Figures

Figure 3. Case 3: Dyscolioid and Terebratuloid gene tree. Best maximum-likelihood tree (GTR + invariant + gamma model) from RAxML with thorough bootstrap support (%), based on 3427 nucleotides of aligned sequences from up to four genes (12S and 16S mitochondrial, and SSU and LSU nuclear) from 19 in-group and three rhynchonellide out-group taxa. Pruned of potentially misaligned and gap sites by hand (7% discarded). In-group backbone nodes with no bootstrap support value attached are considered to be unsupported (may be collapsed; boostrap <50%). Nine taxa, marked (LSU), are represented by LSU sequence data alone, and in each case this sequence clusters with the cognate multiple sequences, indicating that the LSU fragment alone can accurately place the taxon. These results validate the placement of Ebiscothyris, Dallithyris, and Dyscolia, each of which is represented by LSU alone.