Pentapora lacryma Lombardi, Taylor and Cocito, 2010
Colonies reaching at least 12 cm in diameter, forming three-dimensional, box-like growths of bifoliate fronds that are frequently broken into flakes during fossilization. The encrusting colony base is extensive, sometimes develops overgrowths to become multilayered, and may fail to develop erect growth. Each frond has a bifoliate structure, with a median lamina (visible in broken specimens and at growing edges) separating layers of zooids opening on opposite sides.
Autozooids are elongate, on average 0.53 mm long by 0.27 mm wide, and approximately rectangular in outline shape. The frontal shield is slightly convex and evenly penetrated by marginal areolar pores and pseudopores. The orifice is longer than wide, about 0.15 mm long by 0.13 mm wide, with a pair of lateral condyles and a proximal edge indented by the adventitious avicularium. Ovicells are prominent, globular, average 0.19 mm long by 0.24 wide, and have numerous small pores scattered across their entire surface.
Avicularia are adventitious, borne on the frontal shields of the autozooids, located suborally just beneath the orifice and directed proximally. Most are small, averaging 0.09 mm long by 0.07 mm wide, rounded, inclined and have a calcified crossbar. Enlarged avicularia occasionally replace the normal-sized avicularia. These giant avicularia average 0.24 mm long by 0.16 mm wide and are teardrop shaped or spatulate, with a deep palate and a crossbar bearing a knob-like columella.
The fact that Pentapora lacryma remained unrecognized until 2010 and was consistently misidentified as Pentapora pertusa betrays its close similarity to the latter species. If differs, however, in two respects. Firstly, the giant avicularia of P. lacryma are teardrop shaped or spatulate and are smaller and less protruberant than those of P. pertusa. Secondly, the ovicells of P. lacryma have numerous small pores evenly scattered across the surface, whereas those of P. pertusa contain a single large pore. Distinguishing between the two species in the absence of giant avicularia or well-preserved ovicellate zooids, as in many encrusting bases, is difficult or impossible, although the autozooids of P. lacryma tend to be smaller than those of P. pertusa.
Other ascophoran cheilostome bryozoan genera from the Coralline Crag sharing a bifoliate colony form, such as Metrarabdotos and Goodonia, have differently shaped orifices and pore patterns on the frontal shield. The Recent bryozoan Pentapora foliacea (Ellis & Solander), which occurs commonly around the British Isles as the so-called 'Ross Coral', lacks giant avicularia and has the ovicellular pores arranged in a band.
Pliocene, Late Zanclean–Early Piacenzian, Coralline Crag Formation, Aldeburgh and Sudbourne members, questionably Ramsholt Member, Suffolk, UK and Red Crag Formation, Essex