Mackinnon, D. I.; Hiller, N. (2010). Endoskeletal plate development in the recent indo-pacific brachiopod genus Jolonica dall, 1920 (Terebratulida: Laqueoidea). Special Papers in Palaeontology. 84: 193-202.

453629

Mackinnon, D. I.; Hiller, N.

2010

84: 193-202

Publication

In his original description of the Recent terebratellidine brachiopod J. hedleyi, Dall noted the presence of a 'calcareous plate' occupying the posteromedian lacuna of the loop which he attributed to 'coalescence of spicules'. We report on the discovery of a set of three distinctively shaped endoskeletal plates located within the mantle and lophophore tissues of the dorsal valves of adult Jolonica nipponica Yabe and Hatai, and Jolonica suffusa (Cooper). The plates consist of a central, flat and roundly pentagonal-shaped plate occupying the posteromedian lacuna of the brachidium and a pair of gently curved lateral plates enclosing the dorsal diductor muscle bases on either side of the median septum. Although all three plates exhibit a fibrous microfabric similar to the secondary shell mosaic pattern found on the valve interiors of most Rhynchonelliformea, they cannot be regarded as part of the standard secretory regime (sensu Williams 1968a). Examination of a subadult specimen of J. suffusa reveals that the plates formed as a result of amalgamation of isolated spicule-like platelets exhibiting a much less regular microfabric than that found in the plates of adult specimens; the rudimentary platelets in turn almost certainly developed as a result of clumping together of individual membrane-bounded scleroblasts containing intracellular calcite. The reassignment of the south-east African genus Compsoria Cooper, (type species C. suffusa), to Jolonica Dall substantially extends the present-day biogeographic distribution of the latter.

RIS (EndNote, Reference Manager, ProCite, RefWorks)
BibTex (BibDesk, LaTeX)

[Back to search]