Revised descriptions of New Zealand Cenozoic Mollusca from Beu and Maxwell (1990)
(Pl. 2p): GS10195, I44/f8486, Boulder Hill, Wangaloan (hypotype of Finlay & Marwick 1937, pl. 10, fig. 10) (GNS)
Beu & Maxwell (1990): Chapter 5; p. 84; pl. 2 p.
Synonymy: Heteroterma zelandica Marshall 1917, p. 453
Description: Size moderate for family (height 30-65 mm), pyriform; spire low, conical. Protoconch not known. Teleoconch whorls probably 6-8 in largest shells, strongly clasping, reaching up to periphery of previous whorl; sutural ramp concave. Last whorl with prominent peripheral angulation and weaker basal angulation, below which it is strongly excavated and contracted to a long, straight neck. Axial sculpture of short, slightly prosocline, rounded costae (15-18 on last whorl) extending from periphery to somewhat below basal angulation; sutural ramp with a subsutural row of low, rounded nodules, otherwise devoid of axial sculpture apart from growth lines. Spiral sculpture of narrow cords and threads which are noticeably stronger on whorl sides than on ramp or neck. Aperture pyriform, columella long, almost straight except for weak twist at inception of short, unnotched siphonal canal. Inner lip moderately and narrowly callused over columella, thinly callused in parietal region. Outer lip thin, with a broad shallowly arcuate sinus on ramp, slightly convex and almost vertical below.
Comparison: Heteroterma is of uncertain affinity and has been included in the Turridae by some workers. It was assigned to the Tudiclidae by Zinsmeister (1983, p. 1298), and tentatively to the Perissityidae by Popenoe & Saul (1987, p. 12). The type species, H. trochoidea Gabb, 1869, is from the Paleocene of California; other species are recorded from the Californian Paleocene, and possibly from the Late Cretaceous of Patagonia. However, when describing the new species Pyropsis zinsmeisteri from Wangaloa, Stilwell (1993, p. 365) indicated that "Heteroterma" zelandica was wrongly assigned to Heteroterma, and apparently also belongs in Pyropsis. This is part of a Pacific-wide complex of similar genera and species in the Perissityidae, including the similar species Antarctissitys austrodema Stilwell & Zinsmeister (2003) (Late Cretaceous, Seymour Island, Antarctic Peninsula). "Heteroterma" elegans Griffin & Hünicken (1994, p. 267, fig. 7.1, 7.2) (Paleocene, Rio Turbio, southern Argentinean Patagonia) also appears to be a species of Pyropsis, whereas H. tumida (Wilckens, 1903) (Griffin & Hünicken 1994, p. 267, fig. 6.5) (Late Cretaceous in the same succession) probably belongs in another genus, but is too poorly preserved to classify.
Distribution: Wangaloan, Wangaloa Formation Wangaloa (type) (not uncommon); Boulder Hill (common). Also doubtfully recorded from Red Bluff Tuff, Pukekio, Chatham Island (Waipawan).
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)