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Volume 59, 1928
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Three New Recent Volutes from New Zealand.

By A. W. B. Powell.

[Read before the Auckland Institute, 29th May, 1928; received by Editor, 31st May, 1928; issued separately, 30th August, 1928.

Plate 53.

The larger Recent Volutes of New Zealand are separable into two main groups. One of shallow-water occurrence showing considerable variation, characterized by a projecting callus-plate on the columella; and the other from deeper water showing slight variation, characterized by a straight pointed columella, without callus-plate.

To the former group belong the species arabica, swainson, and depressa and to the latter, jaculoides, larochei, and two of the new species described below.

The writer is greatly indebted to Dr. J. A. Thomson and Dr. J. Marwick for the loan of valuable material, to Dr. E. N. Drier for the donation of a specimen as type, and to Mr. H. Hamer for his care and skill with the photography.

Alcithoe swainsoni Marwick (Figs. 1 and 2).

A figure of the holotype, an Upper Pliocene fossil from Kai-iwi is here given, as Marwick was unable to include it in his paper (2p. 294). He states that the division of the arabica-swainsoni group of shells into satisfactory species is a difficult matter.

The writer, however, has observed that typical arabica is quite constant throughout the Auckland and Manukau Harbours and Hauraki Gulf down to 25 fathoms; while swainsoni is the ruling shallow-water type in Wellington Harbour, though but a short distance away at Waikanae both swainsoni and arabica appear to intergrade.

A figure of a Wellington Harbour specimen (Fig. 2) is given for comparison with the Pliocene type (Fig. 1).

A very distinctive depressa-like variety of swainsoni occurs at Muriwai on the West Coast. For many years damaged shells were observed washed up on the sandy beach, and others wedged among the rocks. Recently three live specimens were collected. All are quite constant in having a depressed spire with weak shouldernodules, almost on a line with suture, and in the colour-pattern being weak or entirely wanting. They seem to represent a local race, not observed elsewhere, and are well worthy of subspecific distinction.

Alcithoe swainsoni motutarensis n. subsp. (Figs. 3 and 4).

Shell solid, moderately large. Whorls 5, exclusive of damaged protoconch. Spire low, conic, less than ⅓ height of aperture. Postnuclear spire-whorls faintly nodulous, angled below towards lower

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suture, body-whorl devoid of nodules. Suture almost on a line with shoulder tubercles, which are rather small, regularly spaced, and laterally compressed. Shoulder steep, almost straight. Body-whorl large, inflated. Fasciole prominent, marked off by defined ridge. Aperture large, open, deeply notched below, sub-angled above towards posterior notch. Outer lip thickened and reflexed, ascending less than ⅓ height of penultimate whorl. Columella vertical with large projecting callus-plate and 6 plications, upper two weak, lower four very strong. Inner lip spread as a thin glaze broadly over body whorl, with prominent callosity towards posterior notch. Colour uniform pinkish-buff, with a very obscure pattern in the form of zigzag lines of darker buff, entirely absent towards outer lip. The paratypes show no traces of colour-pattern.

Height, 93.5 mm.; diameter, 42.5 mm. (holotype).

Height, 74 mm.; diameter, 33 mm. (paratype).

Habitat Motutara and Muriwai Beach, West Coast, Auckland (A.W.B.P.).

Holotype and two paratypes in Author's collection, Auckland.

Alcithoe calva n. sp. (Figs 5 and 6).

Shell very large, narrow and elongated. Whorls 8½. Protoconch scaphelloid, moderately large of 2½ smooth whorls. Post-nuclear whorls smooth, devoid of sculpture except in rare instances where spire-whorls are faintly shouldered, showing traces of axial costae. Spire tall, half the height of aperture, whorls slightly convex. Bodywhorl elongate, sub-cylindrical, gradually contracted below to rounded fasciole, not marked off by usual ridge. Aperture long, rather narrow with shallow notch below. Outer lip thickened, reflexed above, ascending about ⅓ height of penultimate whorl. No projecting callus-plate on columella which is straight, tapering to a sharp point below, with six comparatively weak, very oblique plications; upper one more or less rudimentary. Inner lip spread as a thin glaze broadly over body-whorl.

Colour pale buff, ornamented with indistinct irregular light brown zigzag lines. Interior of aperture pinkish-fawn.

Most specimens have the outer. surface badly eroded.

Height, 173 mm.; diameter, 64 mm. (holotype).

Height, 177 mm.; diameter, 64 mm. (paratype).

Habitat off Cape Campbell, Marlborough in 40-50 fathoms (H.Hamilton, 1925). Castlecliff, Wanganui (Upper Pliocene) 1 sp. (A. W.B.P. Jan. 1927).

Holotype and 21 paratypes in Dominion Musuem, Wellington.

This species differs from swainsoni in the elongated shape, weak columella plications, shallow anterior siphonal notch, and absence of projecting columellar callus-plate. Another related species, larochei Marwick, is distinguished by its broadly-fusiform shape and fewer and stronger columellar plications.

Both larochei and calva n. sp. occur commonly at Cape Campbell but do not seem to intergrade.

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1. Alcithoe swainsoni Marwick (holotype) 145 mm. × 61 mm.
2. Alcithoe swainsoni off Rona Bay, Wellington Harbour, 179 mm. × 70 mm.
3. Alcithoe swainsoni motutaraensis n. subsp. (holotype) 93.5 mm. × 42.5mm.
4. Alcithoe swainsoni motutaraensis n. subsp. (paratype) 74 mm. × 33 mm.
5. Alcithoe calva n. sp. (holotype) 173 mm. × 64 mm.
6. Alcithoe calva n. sp. (paratype) 177 mm. × 64 mm.
7-8. Alcithoe johnstoni n. sp. (holotype) 169 mm. × 65 mm.

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Alcithoe johnstoni n. sp. (Figs. 7 and 8.)

Shell very large, elongate, inflated below. Whorls 8½ Protoconch scaphelloid, moderately large, of 2½ smooth whorls. Postnuclear spire-whorls angled at centre and prominently nodulous. Penultimate whorl with 11 strong laterally compressed nodules. Shoulder sloping slightly concave. Body-whorl large, inflated, smooth and devoid of nodules, merged into fasciole without any defining ridge. Spire rather short, less that half height of aperture. Aperture long, expanded at centre, contracted above and below. Anterior siphonal notch shallow. Outer lip thickend and reflexed, uniformly broadly arched, ascending over half height of penultimate whorl. No projecting callus-plate on columella, which is straight, tapering to a sharp point below, with five strong oblique plications. Inner lip spread as a thin glaze broadly over body-whorl. Colour pale pinkish-buff, covered with a network of reddish-brown zigzag lines, becoming heavier and blotched at regular intervals, forming definite spiral bands, two on spire-whorls, four on body-whorl. Parietal callus and interior of aperture uniform pinkish-buff.

Height, 169 mm.; diameter, 65 mm.

Habitat off Cuvier Island, in 44 fathoms.

Holotype in Author's Collection and two specimens in collection of Dr. E. N. Drier, Auckland.

This species is named in honour of Captain Fred Johnston of S.T. “Thomas Currell” who obtained the specimens. It resembles jaculoides in form of spire and columella but differs in the smooth inflated body-whorl and broadly arched outer lip.

Radula.

The extremely simple degenerate radulae of the Volutidae are of little use for classification, as, in the majority of the genera (based on nuclear characters) only the central tooth remains, and it is almost invariably tricuspid. Alcithoe has this common type of radula but it is possible to detect minor specific differences in the form of the tooth and its cusps as illustrated by the accompanying diagrams.

1. Represents 3 of the 69 rows from the radula of Alcithoe arabica (Puketutu Island, Manukau Harbour, on tidal mud-flats. Three radulae compared, characters found constant).

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2. Represents 3 of the 86 rows from the radula of Alcithoe johnstoni (paratype).

Compared with arabica the individual teeth of johnstom are more deeply excavated at base and the cusps are shorter and stronger.

List of New Zealand Recent Volutes.
(with references).

  • Waihaoia (Pachymelon) lutea (Watson) (4, p. 449 & 2, p. 282).

  • Iredalina mirabilis Finlay (1, p. 59).

  • Alcithoe arabica (Martyn) (4, p. 445).

  • Alcithoe depressa (Suter) (4. p. 447).

  • Alcithoe jaculoides (Powell) (3, p. 108).

  • Alcithoe swainsoni Marwick (2, p. 294).

  • Alcithoe swainsoni motutaraensis n. sub sp.

  • Alcithoe larochei Marwick (2, p. 294).

  • Alcithoe calva n. sp.

  • Alcithoe johnstoni n. sp.

  • Alcithoe gracilis (Swainson) (4, p. 448).

  • Alcithoe hedleyi (Murdoch & Suter) (4, p. 448).

Literature Cited.

1. Finlay, H. J., 1926. On Iredalina a New genus: A Volute without plaits. Pro. Mal. Soc., vol. 17, pt. 1, pp. 59-62.

2. Marwick, J., 1926. Tertiary and Recent Volutidae of New Zealand. Trans. N.Z. Inst., vol. 56, pp. 259-303.

3. Powell, A. W. B., 1924. Description of a new subspecies of Alcithoe arabica Martyn from New Zealand. Pro. Mal. Soc., vol., 16, pt. 2.

4. Suter, H., 1913. Manual of the New Zealand Mollusca.

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1. Murdochia aranea n. sp. (3 mm. 1.5 mm.)
2. Aeschrodomus worleyi n. sp. (2 mm. 2.6 mm.)
3-4. Egestula spectabilis n. sp. (0.7 mm. 1.5 mm.)
5. Laoma (Phrixgnathus) larochei n. sp. (2.25 mm. 2.3 mm.)

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6. Cavellia spelaea n. sp. (2.5 mm. 5.25 mm.)

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