Conus (Conolithes) wollastoni (Maxwell, 1978)

DESCRIPTION ⁽¹⁾.

Shell of moderate size for genus, biconic; spire 0.25-0.3 X total height. Protoconch narrowly conical, of about 4 lightly convex, smooth whorls with obscure sutures; nucleus missing in all specimens seen. Teleoconch of up to 9 whorls, obtusely shouldered well below middile on spire; many specimens with shoulder just above lower suture. Sutural ramp flat to gently concave, normally steeper in adults than in young shells; whorls sides sloping inward. Last whorl contracted gradually. Some shells almost straight from shoulder to anterior end, but most very gently convex over posterior two-thirds, straight and slightly oblique below, producing a weakly defined neck. Axial sculpture consisting of small, squarish, opisthocline, peripheral nodules, usually extending a short distance below shoulder but scarcely encroaching on to sutural ramp; about 23-29 nodules on penultimate whorl. Interspaces usually similar in width to nodules. (See below for discussion of atypical specimens from Awamoa Creek, White Rock River, and Tengawai River.) Growth lines moderately prominent on sutural ramp, usually as narrow, sharp, slightly raised ridges, much weaker below shoulder. Spiral sculpture on spire whorls consisting of a few weak threads on sutural ramp and 2 or 4 much stronger, though still weak, threads on shoulder. Last whorl with about 11-14 well defined, narrow grooves confined to anterior half (or less), the anterior ones with narrow, convex inters paces, the others with broad, flat interspaces. Broad zone between topmost basal groove and shoulder occasionally showing 1 or 2 weakly defined grooves, otherwise mooth and polished. Aperture rather narrow, ectangular. Inner and outer lip almost parallel in apertural view. Inner lip typically with a callus pad at posterior end, bounded below by a short, horizontal groove. Outer lip thin, with a moderately deep, arcuate sinus on sutural ramp.

DIMENSIONS OF HOLOTYPE (mm) ⁽¹⁾.

Height (lacking apex) 19.0, maximum diameter 8.2. The largest 'typical' specimen seen, from GS 9500, measures 39.1 x 14.5. Somewhat larger, though atypical, shells are present in GS 165; the largest measures 45.2 x 15.6.

HOLOTYPE ⁽¹⁾.

TM 5447; hypo types TM 5476, 5477.

TYPE LOCALITY ⁽¹⁾.

"Awamoa" (Hutton 1873, p. 10).

Early collections from Awamoa (5 km south of Oamaru) are from two distinct localities:

(a) bluegrey siltstone with scattered macrofossils exposed at intervals along Awamoa Creek for about 800 m upstream from the mouth;

(b) moderately cemented, richly fossiliferous sandstone either exposed on the beach near the mouth of the creek or represented by loose boulders.

The former locality is still readily collectable, but the beach outcrops are nowadays almost continuously covered by sand. The preservation of the type of Conus ornatus and the lithology of the adhering matrix can be matched perfectly among shells collected from the beach outcrops and boulders, and there is little doubt that (b) is the type locality. The very large collection made by Alexander McKay in 1876 (GS 170)-which was "mainly from boulders between high- and low-water marks" (note in original N.Z. Geological Survey register)-contains several hundred cones, most of which agree very closely with the holotype.

The origin of the fossils from "Awamoa" described or recorded by Hutton (1873) is uncertain, but it seems likely that they were presented to the Colonial Museum and N.Z. Geological Survey by Charles Traill. Park (1918, p. 87) states that TraiIl collected from Awamoa in 1869, although Traill does not state specifically where he collected the fossils he listed from the "Blue clay" (Traill 1870). That Hutton used the specific epithet trailli for species of Hinnites, Crassatella, Conus, and Pleurotoma from Awamoa is strong evidence that he was dealing with material collected by Traill.

FORMATION ⁽¹⁾. Rifle Butts Siltstone (Altonian, Lower Miocene).

LOCALITIES ⁽¹⁾.

GS 170, Awamoa Beach and Creek - see note above (several hundred well preserved specimens, including juveniles).

GS 9685, Pukeuri road cutting, North Otago (about 35 shells).

GS 9500, excavation for a Council septic tank, South Oamaru c.2 km N of Awamoa Creek (22).

GS 9700, Sutherlands, Tengawai River, South Canterbury (8).

(All localities of Altonian age.)

Cones from several other Altonian localities in North Otago and South Canterbury differ from those listed above in having the peripheral nodules confined to the first four whorls or so of the teleoconch.

In other respects they are very similar, and are here considered to be variants of C. wollastoni, although it is quite possible that they are distinct taxa. The strength of the peripheral nodules varies considerably in the Awamoa Beach, septic tank excavation, and Pukeuri samples, though among the large number of specimens examined none has the later whorls entirely devoid of them. (The variation in this feature in Pukeuri cones was noted by Suter (1917, p. 84) when he was seeking to demonstrate that Conus ornatus and C. trailli Hutton are conspecific – see below.)

Shells from Ardgowan Shell bed and from GS 11,174 seem partially to bridge the gap between the two morphotypes, in that some have nodules persisting on to the 6th or 7th whorl; the available specimens are, however, rather worn.

Cones having the peripheral nodules absent from later whorls are known from the following Altonian localities:

GS 9520, Awamoa Creek (3 specimens);

?GS 951, Target Gully Shellbed (2);

GS 9521, Ardgowan Shellbed (5);

GS 11,174, shellbed on hillside about 400 m NW of Ardgowan Shellbed (10);

GS 5177, Tengawai River near Sutherlands (5);

GS 165, White Rock River (7).

REMARKS ⁽¹⁾.

As noted above, the cone here named Conilithes wollastoni has long been thought to be conspecific with Conus trailli Hutton (= C. huttoni Tate), also described from "Awamoa". The holotype of C. trailli (Fig. 40) is a very incomplete shell lacking much of the anterior end and having a large part of the front of the spire and upper part of the last whorl missing. The specimen originally measured about 25 X 10.5 mm, and so falls well within the size range of C. wollastoni. There are traces of weak peripheral nodules on the early spire whorls but not on later whorls, giving the shell a superficial resemblance to the smooth-shouldered cones here considered to be variants of C. wollastoni (see above). However, it differs from both forms of wollastoni in having distinct spiral grooves over the whole of the last whorl below the shoulder (assuming the grooves were present on the missing anterior portion also) (see Fig. 40). On this feature alone it falls well outside the observed limits of variation in Conilithes wollastoni, and is considered to represent a distinct taxon. Unfortunately, no other cones from North Otago or South Canterbury Altonian localities examined by me have comparable spiral sculpture, so our knowledge of Conus huttoni is extremely imperfect. The holotype of huttoni is perhaps merely an abnormal form of the species here named Conilithes wollastoni, but at present this is an untestable hypothesis, so it is expedient to recognise two distinct taxa.

The exact provenence of the holotype of C. huttoni is unknown. Matrix within the shell is soft, medium grey-brown siltstone, which suggests that it came from Awamoa Creek itself, but it is just as likely to have come from poorly fossiliferous siltstones interbedded with the shellbeds at Awamoa Beach (Park 1905, p. 511-12).

Conilithes wollastoni is probably related to the somewhat younger species C. rivertonensis Finlay, 1926 (? Clifdenian, Middle Miocene, Pourakino, Southland) and C. oliveri (Marwick, 1931) (Clifdenian, Middle Miocene, Muddy Creek, Gisborne district). Finlay (1926, p. 255) distinguished C. rivertonensis from Conospira bimutata Finlay (Le., Conilithes wollaston i) by its "longer and more exsert spire and narrower shell". Judging by Finlay's illustration of the holotype (the only known specimen) the shoulder is situated much higher up on later spire whorls than in any specimen of C. wollastoni.

Conilithes oliveri seems to be closer to C. wollastoni; Marwick (1931, p. 132) distinguished it "by the more slender form and steeply inclined shoulders", but these features vary widely in both species. A more reliable distinguishing feature is the protoconch, which is considerably larger and more narrowly conical in oliveri than in wollastoni.

Conus wollastoni
Conus (Conolithes) wollastoni (Maxwell, 1978) mm. 32 - (Altoniano, Miocene) Pukeuri, Omaru, South Island, Nuova Zelanda	Conus (Conolithes) wollastoni (Maxwell, 1978) Plate 22 V GS95000, J41/f8028 Excavation for Oamaru Borough Council septic tank South Oamaru – Altonian New Zealand Stage: Altonian (17.5 - 16.5)
Beu & Maxwell (1990): Chapter 11; p. 207; pl. 22 v. Synonymy: Conus ornatus Hutton 1873b, p. 10 (not of Michelotti, 1847); Hemiconus trailli "(Hutton)" of Finlay 1924a, p. 105 (in part not Conus trailli Hutton 1873b, p. 10, not of A. Adams, 1855, = Conus huttoni Tate 1890, p. 189, = Conospira bimutata Finlay 1924d, p. 498); Conospirus huttoni "(Tate)" of Olson in Gage 1957, p. 126 (in part not Conus huttoni Tate, 1890); Conilithes wollastoni Maxwell 1978, p. 42-43 (new name for Conus ornatus Hutton, 1873, preoccupied); Hemiconus ornatus Classification: Conidae: Coninae Description: Rather small to moderate-sized for family (height 20-45 mm), biconic, spire 0.25-0.3 total height. Protoconch narrowly conical, of about 4 smooth whorls. Teleoconch of 8-9 whorls, angled below middle on spire, some shells with angulation just above suture, sutural ramp flat or slightly concave; last whorl straight or weakly excavated. Axial sculpture typically of small, squarish, opisthocline nodules on periphery, extending a short distance anteriorly but obsolete on ramp; 23-29 nodules on penultimate whorl. Some shells with nodules confined to first 4 whorls or so. Sutural ramp with thin, arcuate growth ridges. Spiral sculpture on spire whorls of 2-4 narrow cords on periphery and a few weak threads on ramp; last whorl with 11-14 well denned narrow grooves on anterior half or less, remainder smooth except for 1 or 2 weakly defined grooves on some shells. Aperture narrow, rectangular with inner and outer lips almost parallel and straight. Outer lip thin with shallow, arcuate sinus on ramp. Comparison: Conilithes wollastoni is the best-known New Zealand cone. It has long been identified as Conus (or Conospirus) huttoni, but the type specimen of that species (the only one known) has only weak nodules on the early teleoconch whorls, and has distinct spiral grooves over the whole of the last whorl below the periphery. C. rivertonensis (Altonian, Southland) is more slender and higher-spired than C. wollastoni, and has the shoulder angle situated higher up on later whorls. C. oliveri (Clifdenian, Gisborne district) is similar in shape to C. wollastoni, but has a larger and more narrowly conical protoconch. A recent analysis of Conus coxI-coxII intergeneric sequences (Bandyopadhyay et al., 2008) established that there are two groups of "Conus" species throughout the world ocean, the taller-spired species consistently falling out as a phylogenetic entity separate from Conus, so Conospirus might well prove to be the earliest name for the tall-spired genus, although at present it is uncertain whether this is the correct name for the genus. Distribution: Altonian; Mount Harris Formation, Awamoa (type — probably from the former beach outcrop at the mouth of Awamoa Creek where it seems to have been very abundant) and other localities in North Otago and South Canterbury.

mm. 24,3	mm. 18,6
Conilithes wollastoni (P. A. Maxwell, 1978) Miocene, Altonian, Awamoa Beach, Oamaru, Southland, Nuova Zelanda [Andrea Inzani]

C. antidiluvianus var. tauroascalarata (Sacco, 1893) Langhiano	Conus poulsenii The Gram Formation is a geological formation in Gram, Denmark. It preserves fossils dating from the Miocene period. The formation consists of three layers: the glauconite-rich, the Gram Clay, and the Gram sand.
Il periodo Altoniano si estende da 17,5 a 16,5 Ma, un periodo corrispondente al Burdigaliano: si tratta quindi di un periodo di gran lunga antecedente il Piacenziano, periodo nel quale il Conus antidiluvianus è rinvenuto più frequentemente. Sacco, tuttavia, scrive che esemplari di Conus antidiluvianus sono già presenti a partire dal Langhiano, un periodo di poco successivo all’Altoniano: queste forme più antiche, ad esempo il C. antidiluvianus var. tauroascalarata, sono ancora più simili al Conus wollastoni. La linea che attraversa il tubercoli, ben visibile nel Conus wollastoni, può essere individuata anche in alcuni esemplari di Conus antidiluvianus: sebbene sia molto meno chiara, in alcuni esemplari è più evidente, come ad esempio in questo esemplare del Miocene proveniente dalla Danimarca.

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Bibliografia Consultata

• (1) – “Taxonomic and nomenclatural notes on some New Zealand Cenozoic Mollusca, with descriptions of new taxa” PHILLIP A. MAXWELL