Genus Charonia Gistel, 1848.
Subgenus Charoniella nov.
Type: Charonia (Charoniella) arthritica nov.
The new species described below is undoubtedly congeneric with Austrotriton neozelanica Marshall and Murdoch and Charonia clifdenensis
Figs. 15 & 16.—Baryspira platycephala n. sp. Holotype.
Figs. 17 & 18.—Baryspira platycephala n. sp. Paratype.
Fig. 19.—Turritella (Maoricolpus) waitemataensis n. sp. Holotype.
Fig. 20.—Turritella (Maoricolpus) gittosina n. sp. Holotype.
Fig. 21.—Turritella (Zeacolpus) tetleyi n. sp. Holotype.
Fig. 22.—Turritella (Zeacolpus) tetleyi n. sp. Paratype.
Figs. 23 & 24.—Navicula waitemataensis n. sp. Holotype.
Figs. 25 & 26.—Estea verticostata n. sp. Holotype.
Figs. 27, 28 & 31.—Zefallacia benesulcata n. sp. Paratypes.
Figs. 29 & 30.—Zefallacia benesulcata n. sp. Holotype.
Fig. 32.—Pyrazus consobrinus n. sp. Holotype.
Fig. 33.—Pyrazus consobrinus n. sp. Paratype.
Fig. 34.—Pyrazus waitemataensis n. sp. Holotype.
denesis Finlay. In referring both these species to Charonia, Finlay (Trans. N.Z. Inst., vol. 54, 1924, pp. 461–464) admits the difficulty of separating the various genera of the family.
Typical Charonia is a large symmetrical shell with a large aperture and moderately expanded outer lip; in Austrotriton and Charoniella, however, the shell is small, invariably distorted and with small aperture not projecting beyond the penultimate whorl, whilst the sculpture is in the form of close granulated spiral threads.
Charoniella differs from Austrotriton and comes much nearer to Charonia in the form of the varices, the less-twisted canal and the presence of denticles on the lower columellar lip. Juvenile specimens of Charonia, it may be remarked, do not compare well with Austrotriton or Charoniella, for they are more symmetrical and less distorted.
A solid tuberculate and varicate elongate sub-pyriform turretted shell, with conical spire about equal in height to aperture and canal. Known by a single specimen.
Apical whorls badly eroded: about 7 adult whorls indicated. Outline of whorls irregular: nodular sections angled at one-quarter height above suture; plain sections almost flat. Suture undulating. Body-whorl with strong tubercular angle a little above middle, with concave shoulder above tubercles; a little below this there is an obsolescent faint angle below which there is almost straight or lightly convex moderately rapid descent at the base.
Axial sculpture of varices and weak axial costae produced below at angle into prominent rounded tubercles or nodules in series of 4 or 5 alternating with spaces about one-third whorl in extent free from such nodules. These blank spaces alternate with varices and each represents a ventral surface developed during an appropriate growth-stage. The nodules are also absent near the outer lip.
Varices are prominent only on later whorls; apparently about 1 per whorl. They are sub-vertical, broad and low: that near inner lip of holotype has its outer (left) margin sharply defined and slightly raised, whilst its inner margin fades into inner lip and body-whorl; it is covered by slightly-raised callus-plate of lower inner lip and gradually wedges out against the fasciole, from which it is separated by a groove oblique to the right. Other varices are ill-defined at their margins.
Highly characteristic spiral sculpture of flat-topped threads (about 24 on penultimate and 65 to 70 on body-whorl), reticulated by oblique shallow linear grooves more or less coincident with growth-lines. The spiral threads are stronger and the reticulate structure faint on fasciole. On lower subsidiary angle of body-whorl, to left of varix, a row of 3 nodules has developed closer-spaced than at main angle, whilst the initiation of a still lower equi-spaced nodular series is indicated by a single small but sharp nodule immediately against, the varix.
Aperture small, ovate, with a fairly narrow, rather deep posterior canal above, whilst the anterior canal (imperfect) is indicated as
narrow, short and slightly recurved; it is apparently only shallowly notched below, for the broad low fasciole is not separable from the base. A very prominent tubercle margins the inner side of upper canal, whilst near the outer lip there are 7 small elongate internal denticles. Outer lip sharp, though strengthened by adjacent low, ill-defined varix in holotype. Inner lip with about 3 oval rounded tubercles on lower portion; narrow and lightly-spread callus on parietal wall, thickened into plate below on pillar with strong raised outer edge. Parietal wall concave and continuous in curve with the columella, which is flexed to right.
Ventral surface of body-whorl above aperture free from axial ornamentation.
Dimensions of holotype (in collection of A. W. B. Powell): Height, 50 mm.; breadth, 26 mm.
The new species stands nearest to Austrotriton neozelanica Marshall (Trans. N.Z. Inst., vol. 54, 1923, p. 129), which Finlay (Ibid., vol. 55, 1924, p. 464) has referred to the genus Charonia.