Pycnolepas articulata Collins, 1980

Original description. Collins (1980: 22, figs 2, 3).

Type. Holotype is BAS KG.1657.8b; paratypes are BAS KG.1657.8a, c; all are articulated, near-complete capitula (leg. M.R.A. Thomson).

Locality and stratigraphy. Station KG.1657, northern Hyperion Nunataks, southeastern Alexander Island (Antarctica); Fossil Bluff Formation,?lower Aptian. Associated ammonites and a brachiopod suggest approximate correlation with the Fossil Bluff section, for which an early Aptian age (c. 113–112 Ma) was suggested (Thomson, 1974; see also Crame, 1985).

Remarks. The type lot represents the only articulated material of Pycnolepas known to date. Pycnolepas articulata is a moderately large species with thin, strongly ridged valves; carina subcylindrical, with rounded parietes; tergum subrhomboidal; scutum elongate-triangular, showing one longitudinal ridge more prominent than other ridges on occludent side of apicobasal ridge; rostrum only partially preserved, apparently reaching half the length of scutum; imbricating plates in three or four whorls, subtriangular and with broadly rounded apex, each having narrow basal ridge with shallow, slit-like median socket.

Occurrence. Known only from the type locality; no subsequent records.