GENUS Physoporella STEINMANN 1903
SPECIES Physoporella laevis PRATURLON 1963
holotype: Pl. IV, fig. 2, thin section N° G 1/8, A. Praturlon Collection, Micropalaeontological Collection, Institute of Geology and Palaeontology, Roma (Italy)
type locality: Vallone Secosta, Auronzo di Cadore, Véneto (Italy)
stratum typicum: Upper Permian (Bellerophon Fm, uppermost part of the "Bellerophon-zone")
original description (Praturlon, 1963): « Aspect in thin section – Owing perhaps to a feeble calcification, well-preserved specimens are few. The branches are filled with crystalline calcite, central hollow is frequently marked by dark secondary detritus. Thin calcareous walls, reddish in colour, line axial hollow and single branches. Sections very oblique to the axis show an ellipsis truncated at both extremities (Pl. IV, 4) by meeting of two consecutive whorls with the cutting plane. More elongated sections (Pl. IV, 2, 3) show besides, at regular intervals, lateral branches couples, to each of which corresponds a biseriate whorl. Easily recognizable, but nearly always incomplete the cross-sections. Very rare the axial sections.
Main cell and calcareous wall – Thallus cylindrical, lined with a very thin calcareous layer, which would correspond not to the usual calcareous wall but merely to the calcified cell-membrane. This is a rather rare character among the Dasycladaceae; it seems to be constant in this species, and not in connection with unfavourable lighting.
Branches shape and disposition – Branches euspondyl, alternative in biseriate whorls arranged at regular intervals along the stem (Pl. IV, 1, 2). The branches depart from main cell perpendicular to the axis, but often they get inclined in opposite directions. In their axial sections they appear as egg-shaped bodies, fastened to the wall by means of a brief stalk, not always visible. They swell very quickly in proximal portion, then close to the exterior lengthening in a rather smooth point. We are in presence of the pyrifer type, and it is justifiable to consider them as both assimilatory and reproductive organs. »
Measurements: (see above)
6. Stratigraphic range