Discovery of living Potamolepidae (Porifera: Spongillina) from Nearctic freshwater with description of a new genus Author Copeland, John Author Pronzato, Roberto Author Manconi, Renata text Zootaxa 2015 3957 1 37 48 journal article 10.11646/zootaxa.3957.1.2 8bcc14d8-72d3-4fc0-945d-61d42b38d242 1175-5326 288551 FCF72565-AF25-45AC-8608-9A0C4D312FFD FAMILY POTAMOLEPIDAE BRIEN, 1967 Synonymy. Potamolepidae Brien, 1967 ; Manconi and Pronzato, 2002 ; Potamophloiinae Brien, 1969 [ Type genus Potamolepis Marshall , 1883 ] Family definition (emended from Manconi & Pronzato, 2002 , 2009 ). Spongillina with growth form from encrusting or massive to arborescent with irregular lobes, ridges or branches. Consistency from rigid to stony hard, fragile particularly at the sponge base that generally remains adherent to substrata during sampling. Spongin scanty except for the basal spongin plate and gemmular theca. Surface smooth to irregular with chimneys, to conulose with apices of ascending primary fibers supporting conules. Oscules with exhalant star-shaped canals in some cases. No special ectosomal skeleton except for spicular tufts supporting conules and tangential microscleres in the dermal membrane (only some genera). Choanosomal skeleton irregularly alveolate-reticulate with mono- to paucispicular tracts sometimes ascending towards the surface, skeletal network notably dense at the surface and more loose and irregular at the sponge base. Megascleres strongyles to oxeas from smooth to ornamented by variably dense granules/spines/tubercles. Microscleres, if present, slender oxeas. Gemmules, when present, single to grouped, sometimes free at the sponge base or more frequently sessile and strictly adhering to the substratum by the basal spongin plate. Gemmular theca mono-, bi- to tri-layered, usually of compact spongin, with more or less tangentially embedded gemmuloscleres. Pneumatic layer absent to scarcely developed of fibrous, not chambered spongin. Foramen not always evident. Gemmuloscleres strongyle-like, short to elongate, ovular to variably bent (C-like to button-like) variably ornamented to entirely smooth. A second category of gemmuloscleres as large, stout, spiny to smooth oxeas. Parenchymella larvae entirely ciliated, with spicules.