The micropolychaete Josephella commensalis sp.n. commensal to the scleractinian coral Tarbellastraea reussiana (MILNE-EDWARDS & HAIME, 1850) from the Korytnica Clays (Middle Miocene; Holy Cross Mountains, Central Poland)

Abstract

Tiny calcareous tubes, observable under SEM-magnifications, settled within calyces of colonies of the scleractinian coral Tarbellastraea reussiana (MILNE-EDWARDS & HAlME, 1850) from the topmost part of the Korytnica Clays (Middle Miocene; Holy Cross Mountains, Central Poland), and ascribed to the life activity of micropolychaetes commensal to this coral, are accomodated into the extant genus Josephella CAULLERY & MESNIL, 1896, to represent a separate species, Josephella commensalis sp.n. A coat developed on some tubes, and structured like a dense felt composed of needle-shaped sclerites (presumably aragonitic) associated with a granular precipitate of calcite, is interpreted as having been produced by the infested scleractinian polyps which reacted against the intruders by an immense secretion of calcium carbonate. An abundant occurrence of Josephella commensalis sp.n. on local growth-discontinuity surfaces within the scleractinian colonies may suggest their formation just by temporary overpopulations of the micropolychaetes whose metabolism (? or exploitation) has become fatal to a part of the colony.