Escharella ventricosa (Hassall, 1842)
Colonies are encrusting, multiserial and sheet-like. The ancestrula in Recent colonies is tatiform, 0.3 mm long, with 11 spines surrounding the hemielliptical opesia plus the proximal cryptocyst (Hayward & Ryland 1999, p. 128).
Autozooids are elongate, rounded-rhomboidal in outline shape, moderately large, about 0.50-0.57 mm long by 0.30-0.40 mm wide in colonies from the Coralline Crag. The convex frontal shield is granular, lacks pseudopores and is penetrated marginally by a single row of moderately large, subcircular areolar pores. The primary orifice is wider than long, about 0.08 mm long by 0.14 mm wide, with a lyrula occupying half or more of its width. A peristome is developed laterally and particularly proximally, forming an outwardly flared structure that includes an umbo. Oral spines number 4 in both infertile and fertile zooids. Zooidal basal walls contain an uncalcified window. The ovicell is recumbent on the distal zooid, about 0.30 mm long by 0.40 mm wide, and has an imperforate, coarsely granular ectooecial surface.
Avicularia are lacking.
This species differs from Escharella acuta in having only two oral spines. In addition, the autozooids are typically more elongate, have a well-developed, flared proximal peristome and larger areolar pores.
Pliocene, Late Zanclean–Early Piacenzian, Coralline Crag Formation, Suffolk, UK.
Recent populations of this species are distributed from the western Mediterranean to Shetland, the Faroes and Norway (Hayward & Ryland 1999).