GNS Science

Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)

New Zealand Cenozoic Mollusca

Paracominia lignaria (Powell & Bartrum, 1929)


(Pl. 25e): Oneroa, Waiheke Island, Auckland, Otaian (GNS, ex Fleming Collection)

Beu & Maxwell (1990): Chapter 11; p. 227; pl. 25 e.

Synonymy: Cominella (Paracominia) lignaria Powell and Bartrum 1929, p. 433-434

Type species of Paracominia Powell and Bartrum, 1929

Classification: Buccinulidae

Description: Moderate-sized for family (height 40-52 mm), elongate- ovate, spire about half total height. Protoconch reportedly conical, of about 3 smooth whorls. Teleoconch of about 6 whorls, first 3 convex, later whorls with a very prominent, rounded subsutural fold, bordered below by a narrow sulcus of variable depth; last whorl contracted gradually, profile only slightly interrupted by fasciole. Axial sculpture on early whorls of distant costae reaching from suture to suture, but becoming very weak on subsutural collar and strongest just below sulcus, typically reduced to rounded nodules with little or no axial extension on last whorl; 10 or 11 on penultimate whorl. Spiral sculpture absent from most shells, but present as very weak, low ridges below sulcus on others. Surface covered with numerous, narrow, sinuous, anastomosing lines imbedded in the outer shell layer and differentiated from it by their darker colour, weathering to form a system of fine ridges resembling wood-grain (possibly calcitic rods in the aragonitic shell structure). Aperture pyriform, constricted posteriorly to form a short channel; columella slightly concave above, twisted below to form a short, deeply and obliquely notched siphonal canal; fasciole prominent, bordered above by a narrow ridge but scarcely projecting. Inner lip moderately callused at posterior end, thinly below; outer lip thin.

Comparison: Paracominia lignaria is readily distinguished from other species of Paracominia by its unusual wood-like colour pattern, apparently formed by small, vertically aligned calcitic rods of shell material in the outer shell layer. Paracominia was proposed for buccinulids closely resembling species of Cominella in most shell characters, but differing in having a conical protoconch, and in the presence of a very prominent subsutural fold or collar. The genus has a recorded range of Waitakian to Altonian; most occurrences are in very shallow-water assemblages, and it apparently occupied the same ecological niche as Cominella does now.

Distribution: Otaian, Oneroa, Waiheke Island (type).

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
ISBN 978-0-478-19705-1
ISSN 1177-2441
(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)


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