The rudist bivalve Pironaea milovanovici Kühn, 1935, a multiple-fold Hippuritidae, from south-eastern Spain. Taxonomic implications. Pore and canal system constructional morphology

• The shell characters' ontogenetic and intraspecific variability of Pironaea Milovanovici Kühn is described from a large number of specimens from the same horizon.
• Several Pironaea species are recognized as junior synonyms of Pironaea milovanovici Kühn.
• The pore-canal system of the left valve is described in detail. Its pattern is constrained by the presence of secondary pillars.
• An interpretation of the pore-canal system in the American multiple-fold hippuritids is hypothesized.

The study of the external and internal shell characters of Pironaea milovanovici Kühn, as well as of their ontogenetic and intra-specific variability, observed on abundant, well preserved, and matrix-free specimens from Tavernes de la Valldigna, Valencia province, Spain, revealed that other Pironaea species (e.g. P. bacevicensis Milovanović, P. petkovici Milovanović, Sladić-Trifunović, and Grubić, P. postdalmatinica Pamouktchiev, P. signumpraeverta Pamouktchiev, and Pironaea sp. ex gr. polystyla in Lupu), based on one or a very small number of specimens, are junior synonyms of P. milovanovici Kühn. The pore and canal system of the left valve is described in detail, based on differently weathered valves and differently oriented sections; it is constrained by the presence of secondary pillars in both valves. Being the pore and canal system and its relation with the secondary pillars relatively simple and well understood in P. milovanovici, by comparison, an interpretation of these structures in more complex multiple-fold Hippuritidae such as those of the Americas is hypothesized.