Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 1a): paratype, Boulder Hill, Wangaloan (Auckland Museum)
(Pl. 1c): paratype, Boulder Hill, Wangaloan (Auckland Museum)
Beu & Maxwell (1990): Chapter 5; p. 78; pl. 1 a, c
Synonymy: Cucullastis barbara Finlay and Marwick, 1937, p. 20- 21
Type species of Cucullastis Finlay and Marwick, 1937
Description: Moderately large for family (length 60-73 mm), subquadrate, strongly inflated, with a broad, shallow depression running radially across middle of disc, forming a shallow sinus in middle of ventral margin. Umbones very high. Left valve with about 35 narrow, rounded radial costae on anterior and middle parts of shell, well preserved specimens with numerous very fine radial threads as well. Posterior area almost smooth except for radial threads and growth ridges. Right valve with about 50 relatively broad, flat-topped radial costae, each with a narrow median groove and rendered finely scaly by growth lines. Hinge relatively narrow, with rather few (3 or 4), long, subhorizontal, striated teeth at each end. Adductor muscle scars large, posterior scar with prominent myophoric ridge. Inner margin crenulate.
Comparison: Cucullaea barbara differs markedly from C. inarata in its more elongate shape, its medially concave ventral margin and its narrower hinge and, most importantly, in having definite radial sculpture. Younger New Zealand species of Cucullaea (which were assigned to the subgenus Latiarca by Boreham (1965, p. 8, 13)) have less prominent umbones and have radial sculpture of broad, flattened costae in both valves, though these are more subdued in the left valve than in the right. The significance of subgenera in Cucullaea is debatable, but the ones introduced by Finlay & Marwick (1937) are retained here.
Distribution: Wangaloan, Boulder Hill (type); Wangaloa (rather uncommon at both localities).
Cite this publication as: "A.G. Beu and J.I. Raine (2009). Revised
descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990). GNS
Science miscellaneous series no. 27."
© GNS Science, 2009
(Included with a PDF facsimile file copy of New Zealand Geological Survey Paleontological Bulletin 58 in CD version from: Publications Officer, GNS Science, P.O. Box 30368 Lower Hutt, New Zealand)