Tetraphalerella is an extinct genus of stationary epifaunal suspension feeders
Identification in Hand Sample:
- Larger shell, more strongly transverse outline, more prominent and well-arranged pseudopunctae, and much thinner socket ridges that are undercut and dip posteriorly than Strophomena
- Pseudopunctae arranged in radial rows, whereas they are irregularly distributed in Strophomena
- Ventral adductor muscle scars completely enclosed by diductor scars
- Socket plates more recurved laterally back toward the hinge line
- Dorsal transmuscle ridges not known
- Very similar to Strophomena. On weathered or etched specimens, pseudopunctae in Tetraphalerella can be seen to be arranged in radial rows, whereas they are irregularly distributed in Strophomena.
Jin & Zhan (2001):
- Remarks: Wang (1949) initially distinguished Tetraphalerella from Strophomena by its generally larger shell, more strongly transverse outline, more prominent and well-arranged pseudopunctae, and much thinner socket ridges that are undercut and dip posteriorly (see also Jin et al., 1997). Dewing (1999) proposed a new family, the Tetraphalerellidae, largely on the basis of the microscopic shell structure of Tetraphalerella, which has uncored pseudopunctae arranged in regular radial rows, particularly in the anterior part of the disc area. The pseudopunctae of Strophomena, in comparison, have a smooth telolate core and are usually arranged ireegularly over the entire shell. Dewing (1999) further proposed a closer affinity of Tetraphalerella to Coolinia than to Strophomena in terms of their dentiulation and cardinal process. Shells of Tetraphalerella from both the Hudson bay Lowlands (Jin et al., 1997) and southern Manitoba confirm Dewing’s observation on the characteristic development of pseudopunctae of the genus. The consistency of the size and arrangement of pseudopunctae, however, need further investigation. Some shells of Tetraphalerella from the Hudson Bay Lowlands, for example, may have pseudopunctae regularly arranged in radial rows in the disc area but randomly arranged in the marginal, geniculate part of the same valve (Jin et al., 1997). Pending a broader survey of shell microstructures in the strophomenoids and a thorough evaluation of the taxonomic importance of pseudopunctae, the genus Tetraphalerella is retained provisionally here in the Stophomenidae.
- In the revised brachiopod volumes of the Treatise on Invertebrate Paleontology, Cocks and Rong (2000) treated Tetraphalerella as a subgenus of Strophomena without taking microscopic shell structures into consideration. Because of the opposing views of Dewing (1999) and Cocks and Rong (2000), Tetraphalerella and Strophomena are retained herein as independent genera.
Treatise on Invertebrate Paleontology, Part H, Vol. 2 (2000)::
- Similar to Strophomena but with small ventral adductor muscle scars completely enclosed by diductor scars; socket plates more recurved laterally back toward the hinge line; dorsal transmuscle ridges not known