Acarnus Gray, 1867

Nascimento, Elielton & Pinheiro, Ulisses, 2023, A new species of Acarnus Gray, 1867 (Porifera, Demospongiae, Acarnidae) from NE Brazil, Zootaxa 5293 (3), pp. 521-540 : 522-523

Genus Acarnus Gray, 1867

Type species: Acarnus innominatus Gray, 1867

Definition: Non-fistular Acarnidae with cladotylote echinating spicules ( Hooper 2002).

Diagnosis: Non-fistulose, encrusting to massive growth forms; ectosomal tylotes with microspined ends, forming tangential or paratangential tracts (not brushes); choanosomal skeleton isodictyal, isotropic or anisotropic reticulate, occasionally plumo-reticulate or plumose or hymedesmioid in encrusting species; skeletal tracts cored by smooth styles, echinated by 1 or 2 (exceptionally 3) categories of cladotylotes, echinating acanthostyles present or absent; microscleres are palmate isochelae, toxas of several morphologies, smooth microxeas and acanthoxeas (emended from Hooper 2002, changes are in bold).

Remarks: Hooper (2002) indicates the presence of cladotylote, styles, tylotes, acanthostyles, palmate isochelae and toxas of several morphologies as the spicule complement. However, acanthoxa and smooth microxea have been recorded for the genus in the present study (found so far only in Acarnus microxeatus sp. nov.).