Beschreibung:
AbstractWe record for the first time a nominal species of the genusMicrosclerodermain the Western Atlantic, and the first record of the genusAmphibleptulain Mexico. Two new species of ‘lithistid’ Tetractinellida are described:Microscleroderma mexicasp. nov. from crevices of two reefs in Veracruz, Mexico, andAmphibleptula aaktunsp. nov. from the anchialine cave El Aerolito, Cozumel Island, Mexico.Microscleroderma mexicasp. nov. is characterized by its tubular and cup-shaped to wavy laminar habitus, hirsute surface and two size categories of oxea diactines.Amphibleptula aaktunsp. nov. is characterized by its ficiform or lobular habitus with an exhalant area at the flat top of the body, divided into numerous vertical septa-like structures; its desmas have thinner epirhabds, and thinner oxea than those ofAmphibleptula madrepora. This is the second species ofAmphibleptulathat has been described; hence, we propose the redefinition of the genus. Both species described have a shallow distribution (≤21 m depth); they are differentiated from each other by the disjunction between their habitats as well as by their morphology.