Remarks on Bacinella irregularis Radoicic, 1959 (type species B. irregularis) and its representatives.

Abstract

Bačinella irregularis was described by RADOIČIĆ (1959) as an alga incertae sedis. Based on material from the Lower Aptian of the western Maestrat Basin (Spain), the genus Bačinella with its various species is revised; an emended diagnosis is given as well as a detailed description. Bačinella is interpreted as an organism excavating complex branching galleries into biogenic hard substrates, e.g., the crusts of Lithocodium aggregatum ELLIOTT (such as in the holotype specimen of B. irregularis). Its morphology and boring pattern is comparable to that of modern filamentous-septate euendolithic green algae of the class Ulvophyceae. These forms, however, are microfilamentous (microborer) whereas Bačinella has larger filament diameter. Nearly all of the 'Bačinella irregularis' occurrences reported in the literature do not belong to this taxon, but represent irregular vesicular crusts ('bacinellid' fabrics = Bačinella irregularis auct. non) that display some resemblances with modern microbial mats.