Pyrisinellidae, a new family of anascan cheilostome bryozoans

Abstract

A new family of anascan-grade cheilostome bryozoans, Pyrisinellidae n. fam., is introduced, together with two new gen-era, Pyrisinella n. gen. and Spinisinella n. gen. Containing species previously assigned either to the large, paraphyleticCalloporidae, or Microporidae, pyrisinellids are characterized by having small autozooids with a conspicuous pear-shapedridge formed by the mural rim and distal rim of the opesia, articulated oral spines, and hyperstomial ovicells recumbenton the distal zooid and indenting its mural rim. Five species of pyrisinellids are described, two of which are new: Spin-isinella zagorseki n. gen. et sp., from the Cenomanian or Turonian (Upper Cretaceous) of the Czech Republic, and Seto-sinella perfluxa n. sp., from the Langhian (Middle Miocene) of Kalimantan, Indonesia. A Recent species, Megaporaringens (Busk), is redescribed and questionably assigned to Pyrisinellidae. Important evolutionary changes within Py-risinellidae having parallels elsewhere among anascan cheilostomes include: (1) the development of opesiules for passageof the parietal muscles which correlates with a change from a trifoliate to a semielliptical opesia; and (2) the transitionfrom an open spinose ovicell in the oldest species (Spinisinella zagorseki) to a conventional ovicell with a solid hood-like ooecium that characterizes all other species belonging to the family.