Tenactisgen. nov. (Actiniaria, Haloclavidae) a new genus of sea anemones from the Gulf of California, Mexico

Abstract

We describe and illustrate a new genus and species of sea anemone from the intertidal in the Gulf of California (Mexico).Tenactisgen. nov. is characterized by mesenteries decamerously arranged, a single pair of directives attached to a single and strong siphonoglyph, small conchula, endodermal marginal sphincter muscle, pedal disc with basilar muscles, cinclides in pedal disc and proximal column, column with verrucae and pseudoacrorhagi, and a cnidom withp-mastigophores A2 andp-mastigophores B1 and B2a.Tenactis riosmenaigen. et sp. nov. is characterized by having a column not divisible into regions with longitudinal rows of verrucae distally and pseudoacrorhagi forming spherical structures at the tip, only 10 pairs of perfect mesenteries, diffuse endodermal marginal sphincter muscle andp-mastigophores A2 andp-mastigophores B1 and B2a in the filaments. Because of the decamerous arrangement of the mesenteriesTenactisgen. nov. most closely resembles some members of Actiniidae, Haloclavidae, Minyadidae, Oractiidae and Limnactinidae (Actinioidea), Halcampidae (Metridioidea) and Halcuriidae (Actinernoidea). However, the combination of having a decamerous arrangement of mesenteries, single siphonoglyph, conchula and cinclides indicate this new genus belongs to Haloclavidae. Additionally, the presence of a diffuse endodermal marginal sphincter muscle, basilar muscles, a single pair of directives, column with longitudinal rows of verrucae distally and pseudoacrorhagi,p-mastigophores A2, andp-mastigophores B1 and B2a in the filaments distinguishTenactis riosmenaigen. et sp. nov. within Haloclavidae. This is the first record of the family Haloclavidae for the Gulf of California.