Family Dactylocalycidae Gray, 1867

Abstract

Dactylocalycidae Gray (Hexactinellida, Hexactinosida) is returned from Lychniscosida to Hexactinosida due to lack of convincing evidence for interpretation of its dictyonal nodes as lychniscid. It is distinguished among Hexactinosida by lack of side-to-side fusion of dictyonal rays in its primary framework, and thus its members bear beams with single axial filaments. Three Recent genera, including five species, are assigned to the family: the type genus Dactylocalyx, Auloplax, and Iphiteon, the latter here recognized as the senior synonym of Schmidt’s Margaritella and Joannella. Diplacodium Schmidt is transferred to junior synonymy of Dactylocalyx. All forms are thick- walled bodies constructed of branching and anastomosing tube systems, sometimes including cavaedial systems within body profile, but in the type genus, a single continuous labyrinthic complex without an associated cavaedial system is present. Channelization of the thin tubule walls is absent or barely marked in one genus as hemispherical depressions on both dermal and atrial tube surfaces. Spiculation includes pentactins, commonly with hexactins, as dermalia and atrialia, where they occur. Microscleres include discohexasters or disco- hexactins, with or without tylohexasters, onychexasters or oxyhexasters. Small uncinates without barbs occur in one genus but sceptrules are lacking (with one possible exception). The family is entirely Atlantic in distribution, roughly between 30N and S latitudes, and has been recovered from depths of 88–2500m.