Zoila platypyga ( McCoy, 1876 )

Darragh, Thomas A., 2011, A revision of the Australian fossil species of Zoila (Gastropoda: Cypraeidae), Memoirs of Museum Victoria 68, pp. 1-28 : 17

Zoila platypyga ( McCoy, 1876)

Figures 2A , 11A–H , 12A–G , 13A–C

Cypraea (Aricia) platypyga McCoy, 1876, p. 39 , fig. 1-1c.

Cypraea (Aricia) consobrina McCoy, 1877, p. 36 , pl. 49, fig. 2.

Cypraea toxorhyncha Tate, 1890, p. 210 .— Tate, 1892, p. 5, fig. 6; pl. 6, fig. 5.

Cypraea platypyga McCoy. — Tate, 1890, p. 211.

Cypraea (Erosaria) platypyga McCoy. — Harris, 1897, p. 209.

Gisortia platypyga (McCoy) .— Vredenburg, 1927, p. 43.

Gisortia consobrina (McCoy) .— Vredenburg, 1927, p. 43.

Zoila (Zoila) platypyga platypyga (McCoy) . — Schilder, 1935, p. 338.

Zoila (Zoila) platypyga simplicior Schilder, 1935, p. 338 .

Zoila (Zoila) consobrina (McCoy) .— Schilder, 1935, p. 338.

Zoila (Zoila) toxorhyncha (Tate) .— Schilder, 1935, p. 338.

Zoila platygyra [sic] (McCoy). — Wilson and Clarkson, 2004:51, pl. 52, pl 53 ( toxorhyncha ) form.

Zoila consobrina (McCoy) . — Wilson and Clarkson, 2004:51, pl. 54.

Description. Shell of five to six whorls, solid, of medium size for genus, globose to subpyriform, last whorl covered with glaze, enveloping the previous whorls, somewhat humped posteriorly with posterior dorsal slope steeper than anterior; smooth dorsal surface. Spire slightly projecting, of 4–5 whorls, covered with thick callus on most specimens. Protoconch smooth, of one whorl merging imperceptibly with teleoconch whorls; beginning of protoconch slightly immersed. Posterior canal with rounded sides, wide, notched, projecting posteriorly on most specimens with prominent solid lateral projections, longer on columellar side. Anterior canal subcylindrical, narrow, deeply incised, reflexed dorsally and supported by thick lateral flanges on most specimens; on large specimens canal considerably extended.Aperture narrow, very slightly curved, slightly wider and steeply sloping inwards at anterior end before anterior canal; outer lip with 24–33 well-developed teeth extending along entire lip. Columella with 24–33 strongly developed ridges, extending along entire columella, bifurcating on some specimens, not extending onto fossula. Fossula well developed, concave, broad and spoon-shaped, bounded anteriorly by well-developed single terminal ridge.

Dimensions.

Type locality. ‘Tertiary clays of shore near foot of Mount Eliza’.

Type material. Holotype P12137, collected Geological Survey of Victoria . Holotype of Cypraea (Aricia) consobrina P12134, Moorabool River . Holotype of Cypraea toxorhyncha Tate, 1890 , SAM T832 , Muddy Creek , Ralph Tate collection . Holotype of Zoila (Z.) platypyga simplicior Schilder, 1935 , BM (NH), Muddy Creek , E.O. Teale collection (specimen missing). Figured specimen P304414, F.A. Cudmore collection, collected 1941. Figured specimen P304415, presented Mr J. T. Cunningham, 22 February 1966. Figured specimen P14954, collected F.A. Cudmore, February 1932 .

Time range. Balcombian–Bairnsdalian, Middle Miocene.

Occurrence and material. Balcombian. Muddy Creek Formation: Muddy Creek (P14639, P61587, P304426, P308692-4, P308696, P308748, P308798, P308796, 21 specimens); PL3082 Clifton Bank (P58641, P304419, P304434, P304446, P308691, P308695, P308697, 16 specimens) .

Gellibrand Formation : Gellibrand River (P304424, P304448, P308734, four specimens) ; northwest of Princetown (P304441, one specimen) ; Princetown (P5347, one specimen); PL3060 dam on lot 393 (P304429, one specimen) ; 4 km north of Port Campbell (P304439, one specimen) ; between Pt. Ronald and Gibsons Beach (P304444, one specimen) ; Cowley Creek (P304438, one specimen) ; dam at Clyne’s house (P308698, one specimen) ; north of Port Campbell (P308699, one specimen) ; Curdies (P59228, one specimen); PL3068 southwest end of Gibson Beach (P304443, one specimen) .

Fyansford Formation: PL3078 Fossil Beach (P304427-8, P304437, P304415, ten specimens); Balcombe Bay (P308751-3, three specimens) ; Schnapper Point (P308755, two specimens); Braeside Tunnel (P30445, one specimen); Campbells Point (P304436, one specimen); PL3069 Red Bluff, Shelford (P304435, one specimen) ; Shelford (P304420, one specimen); Overburden, Batesford Limestone Quarry (P308811, P309021-3, P310316, P310313, six specimens).

Cadell Marl: PL3084 south of Morgan , South Australia (P304430, one specimen) .

Bairnsdalian

Fyansford Formation : Grices Creek (P14594, P304425, five specimens); PL3103 downstream Grices Creek (P308754, one specimen) ; Grices Creek , middle beds (P304414, one specimen); PL3100 Murgheboluc 4A (P308735, one specimen) .

Remarks. The holotype of Cypraea consobrina McCoy is a slightly immature, water-worn specimen found in the Moorabool River near Geelong, washed out of the Fyansford Formation. The posterior and anterior canals are not so highly callused, even when allowing for wear, as typical specimens of Z. platypyga . However, these forms intergrade and it is synonymised with the latter.

The holotype of Cypreaea toxorhyncha Tate is a large specimen, with the extensions of the posterior canal very well developed. The anterior canal is very long and reflexed dorsally. Similar specimens are associated with and intergrade with typical Z. platypyga specimens in the Muddy Creek Formation and the Fyansford Formation. This name is also synonymised with Zoila platypyga . The holotype of Zoila (Zoila) platypyga simplicior Schilder, 1935 , said to be in the Teale collection, Natural History Museum, London, cannot be located. Schilder indicated that it came from Muddy Creek and that it differed from Z. platypyga sensu stricto by having less produced and less rounded extremities, less developed lateral flanges and a less projecting spire. The posterior extremity was bent to the left.These differences in callus development are minor intraspecific variations, as the specimens illustrated in figs. 11–13 show. Schilder stated that it bore a resemblance to Z. consobrina and that it came from a younger horizon than the latter. In fact, the holotype of consobrina comes from the same stratigraphical horizon.

Figures

Figure 2. Protoconchs. A, Zoila platypyga (McCoy, 1876), P308781, × 7; B, Zoila gigas (McCoy, 1867), P308792, × 3.6; C, Zoila viathomsoni sp. nov., WAM × 10.

Figure 11. A–H, Zoila platypyga; A–B, D, H, holotype, P12137, Mount Eliza, × 1; C, E, holotype of Cypraea consobrina McCoy, P12134, Mooroobool River, × 1; F–G, holotype of Cypraea toxorhyncha Tate, SAM T 823, Muddy Creek, × 1.

Figure 12. A–H, Zoila platypyga; A–D, G, P14594, Grices Creek, × 1; E–F, P304414, Grices Creek, × 1.

Figure 13. A–C, Zoila platypyga, P304415, PL 3078, × 1; E–H, Z. gigas; E, protoconch, P308804, Muddy Creek, × 2.5; F, protoconch, P308807, Batesford Quarry, × 2; G–H, holotype of Cypraea dorsata Tate, SAM T849, Muddy Creek, × 1.