Description:
<jats:title>Abstract</jats:title><jats:p>We record for the first time a nominal species of the genus<jats:italic>Microscleroderma</jats:italic>in the Western Atlantic, and the first record of the genus<jats:italic>Amphibleptula</jats:italic>in Mexico. Two new species of ‘lithistid’ Tetractinellida are described:<jats:italic>Microscleroderma mexica</jats:italic>sp. nov. from crevices of two reefs in Veracruz, Mexico, and<jats:italic>Amphibleptula aaktun</jats:italic>sp. nov. from the anchialine cave El Aerolito, Cozumel Island, Mexico.<jats:italic>Microscleroderma mexica</jats:italic>sp. nov. is characterized by its tubular and cup-shaped to wavy laminar habitus, hirsute surface and two size categories of oxea diactines.<jats:italic>Amphibleptula aaktun</jats:italic>sp. 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 of<jats:italic>Amphibleptula madrepora</jats:italic>. This is the second species of<jats:italic>Amphibleptula</jats:italic>that 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.</jats:p>