The value of cytological criteria in distinghuising sponges at the species level: example of the genus Polymastia

We examined the value of using cytological criteria for sponge taxonomy within the well-defined genus Polymastia and redescribe the species Polymastia janeirensis comb.nov. Comparison of the anatomical, morphological, and skeletal characteristics of P. janeirensis with those of the 17 other known Atlantic species demonstrated that P. janeirensis is closely related to P. agglutinans and P. mammillaris. The study confirmed that the close relationship between P. janeirensis and P. mammillaris can also be recognized at the cytological level. We conclude that cytological criteria can be used for the identification of sponges at the species level, and that these criteria may provide useful information about phylogenetic relationships among sponges belonging to genera with many species and a wide geographical distribution.