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Journal of Paleontology 90(1):31–42
Maxwell did not present any evidence for their inclusion and movement of P. neozelanica in Ptychatractinae, the mostly poorly known subfamily in the Turbinellidae (Harasewych, 1987, p. 167). The poorly preserved nature of the ‘Wangaloan’ species, represented by a single incomplete and eroded speci- men, hinders any in-depth treatment of its identify and affinities. As stated earlier in the discussion of Wangaluta henaconstricta n. gen. n. sp., P. neozelanica is probably a Wangaluta, but it is distinct from the newly described species. Additional collecting at Boulder Hill and Wangaloa has yielded no further examples of this enigmatic species.
Subfamily Zidoninae H. and A. Adams, 1853 ( = Alcithoinae Pilsbry and Olsson, 1954)
Genus Alcithoe H. and A. Adams, 1853
Type species.—(by subsequent designation, Cossmann, 1899) Voluta pacifica (Solander MS) Perry, 1811.
Paleobiogeographic element.—Paleoaustral (possibly endemic) as interpreted herein.
Alcithoe s.l. wangaloaensis new species Figure 6F
Diagnosis.—Small- to moderately sized volute with a robust, low fusiform, stumpy shell; sutures clasping, mostly concealing axials of succeeding whorls; spire angle 67°; last whorl capa- cious, obtusely angulate with nearly vertical sutural ramp; sculpture of about nine inflated, broad, separated, axially extending ribs strongest at angulation and fading abapically along slow to moderately rapid basal constriction; columella with at least four oblique plaits; differs from A.(Leporamax) consisa Marwick, 1926a, and A.(Alcithoe) cylindrica Marwick, 1926a, in having a more squat shell, low fusiform profile, smaller shell, more capacious last whorl, more clasping suture and more concealed axials on spire whorls.
Description.—Shell small- to medium-sized for family (32.0mm high nearly complete), robust, low fusiform, stumpy
or squat; spire low of at least four small, gently concave, nearly flush, subtrapezoid whorls; whorl inflation very rapid from penultimate to last whorl; spire angle approximately 67°; pro- toconch unknown; sutures clasping, wrapping around succeed- ing whorls, nearly concealing axially extending ribs apart from adapical ends of ribs creating a sutural noded effect; last whorl capacious, obtusely angulate, moderately broad, and elongate, adapical sutural ramp of last whorl very steep, nearly vertical, smooth without sculpture, moderately long and concave; basal constriction slow to moderately rapid; sculpture of about nine inflated, broad (c. 3.5 mm), rounded, widely separated, axially extending ribs, strongest at shell periphery and fading abapically towards siphonal canal; axials originated abruptly at angulation and are concave inbetween; no spiral sculpture discernable; growth lines feeble, weakly prosocline on ramp becoming more orthocline abapically; siphonal canal details unknown due to being fragmentary, but probably short; columella slightly con- cave to mostly straight, bearing at least four oblique, spaced plaits centrally; outer lip probably moderately thin, if complete.
Dimensions.—Holotype OU 41228 height 32.0mm nearly complete, diameter of last whorl 18.5mm nearly complete.
Type.—Holotype OU 41228.
Type locality.—Mitchells Rocks, Wangaloa, southeastern Otago, South Island, H46/f166A. Figured specimen.—OU 41228. Material.—Holotype.
Stratigraphic range.—Wangaloa Formation, ‘Wangaloan’ Stage = lower part of Teurian Stage, Danian, early Paleocene, probably G. golzowense Zone, Wilson, 1992b, ca. 64–62 Ma.
Geographic distribution.—Wangaloa, southeastern Otago.
Discussion.—The affinity of this small, unusual, new volute appears to lie with Alcithoe and if it does, indeed, belong to this group, it is then the oldest recorded member, previously repor- ted in rocks no older than the Eocene. The previously described Wangaluta henaconstricta n. gen. n. sp. is easily separated from Alcithoe s.l. wangaloensis n. sp. in having a higher spired fusi- form outline and presence of a subsutural band, compared to the latter ‘Wangaloan’ species that has a low fusiform or more squat profile, a steep adapical sutural ramp without a swelling or axial sculpture, and broader and fewer axial ribs. These two taxa are doubtfully closely related. The complete shell of Alcithoe s.l. wangaloaensis n. sp.
probably had an outline, suture and sculpture close to Alcithoe (Leporemax) concise Marwick, 1931 (p. 127, fig. 271; Fleming, 1966, p. 356, pl. 129, fig. 1500) from the New Zealand Opoitian (lower Pliocene). Alcithoe s.l. wangaloaensis n. sp. is lower spired with a more squat profile, has a more capacious last whorl, more pouty and clasping sutures and more concealed axials on the spire whorls. The Altonian (upper lower Miocene)
species Alcithoe cylindrica Marwick, 1926a (p. 290, pl. 65, fig. 3; Fleming, 1966, p. 344, pl. 123, fig. 1471; see discussions of synonyms A. wekaensis, A. compressa, A. armigera, A. robusta and A. sequax (all Marwick, 1926a) in Beu and Maxwell, 1990 p. 206, especially A. robusta Marwick, 1926a, p. 291, pl. 65, fig. 5) is also comparable to A. s.l. wangaloaensis n. sp., differing mainly in its higher spire, less clasping suture, much larger size and sculptural details. Alcithoe s.l. wangaloaensis n. sp. may represent a new
genus or subgenus, but better-preserved material is necessary to secure relationships.
Etymology.—Species named after its discovery at Mitchell Rocks, Wangaloa.
Genus Teremelon Marwick, 1926
Type species.—(by original designation) Scaphella tumidior Finlay, 1926 (= Waihaoia (Teremelon) awamoaensis Marwick, 1926).
Paleobiogeographic element.—Paleoaustral.
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