Towaipecten ongleyi (Marwick, 1965)
MARWICK, J. 1965. Upper Cenozoic Mollusca of Wairoa District, Hawke's Bay. New Zealand Geological Survey Paleontological Bulletin, 39: 1-83, pls. 1-11. [p. 22, pl. 1, figs. 3, 5; pl. 2, fig. 6]
1965 Phialopecten ongleyi Marwick, 1965
J. Marwick, 1965, plates 1, 2.
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«Shell moderate to fairly large; left valve moderately to well inflated, right valve gently inflated; some specimens with about four vveak apical folds. Sculpture of 26-30 or more main ribs of fairly equal strength in youth, but differing more with age, also several much finer radial ridges along dorsal margins. In youth most main ribs flattened on top and separated by interstices of about equal width; medial grooves in the ribs start at about 30 mm diameter and persist into adult, some remaining comparatively shallow, but others dividing the rib into two distinct parts; most specimens have a few ribs with two grooves and so are medially crested, some have many such ribs; interstices generally with a strong secondary, many of which start about 20 mm diameter and some rival in strength the divisions of primary ribs, but mostly they are of only moderate strength; whole surface, where unworn, with close, regular, sharp transverse ridges. Ears large, subequal, each bearing four or five strong, rather distant, radials; byssal notch well defined, deep until about half-grown, then becoming progressively shallower.
HOLOTYPE: N.Z. Geological Survey (right valve), TM2711.
Length, 77 mm; height, 77 mm; inflation, 10 mm. PARATYPES (left valve): 84 X 87 X 18 mm., TM2713; right valve, 2712. LOCALITIES: GS2604, stream t mile SE of Otamaharua (Trig G), Hangaroa Survey District (type). GS871, Ormond Limestone, \Vaihirere Stream, Waimata Survey District. GS1532, 20 ft limestone, Te Reinga - Ruakituri road. GS1849, 10 ch. north of Trig 90, Waiau Survey District. OS1994, divide 1 mile north of Whakapunake Trig. GS1996, limestone down Hangaroa River from Bushy Knoll Road. GS1998, limestone at Mangamate Stream, Hangaroa River. GS2045, Hangaroa River, 32 ch. downstream from l\1angamate Stream. GS2852, shelly sandstone and limestone, Hangaroa-Tiniroto road, about 3 miles SSW of Hangaroa. AGE: Opoitian.» JOHN MARWICK, 1965
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«REMARKS: The previous confusion between eastern North Island typical populations of weakly costate Towaipecten ongleyi ard the small Opoitian specimens of Phialopecten marwicki that occupied most of the rest of New Zealand was discussed above under P. marwicki. Towaipecten ongleyi seems to have occupied much or all of eastern North Island during early Opoitian time, to judge from the fauna of the Ormond, Opoiti and Haurangi Limestones and of Maungaharuru Formation, and occurs in the late Opoitian Kairakau Limestone with P. marwicki, but l am not aware of specimens of T. ongleyi from outside eastem North Island. This interpretation means that the Opoitian T. ongleyi ranges from 70 to 100 mm in adult height, with an enormously variable number of very low, wide, closely spaced radial costae (ranging from 23 to 46; frequency peaking at 31-32 costae). A single low, wide secondary costa almost fills most intercostal spaces. Primary costal surfaces are weakly to quite strongly subdivided into two or three riblets by weak to prominent grooves, but in most specimens with two grooves the costal surface remains low and strap-like, without the raised median riblet (fasciculate profile) of Phialopecten marwicki. Radial interspaces and, on a few well preserved specimens from siliciclastic lithologies, entire valve surfaces are crossed by low, thin, sharp, moderately widely spaced, simple commarginal lamellae. Auricles are relatively small and have a moderately deep byssal notch and sinus in small to half-grown specimens, after which the byssal notch and sinus are somewhat reduce, but remain obvious.
DISTRIBUTION: Apparently limited to eastern North Island. The sole moderately large, obvious pectinid (i.e. apart from small Talochlamys and Mesopeplum species) present in Opoiti Limestone, Ormond Limestone, Maungaharuru Formation and Haurangi Limestone (all early Opoitian); occurs with Phialopecten marwicki in Kairakau Limestone (late Opoitian). A few similarly sculptured but larger specimens (height to 110 mm), with radial costae becoming weak over the ventral half of the disc, from Tahaenui Limestone on Mahia Peninsula (GS8114, X20/f7613; GS15025, X20/f11; both from Long Point, west coast of Mahia) appear to represent the single Waipipian record of Towaipecten. Towaipecten is entirely absent from Waipipian Te Aute lithofacies of northern Hawke's Bay to Wairarapa. AGE: Limited to Opoitian, apart from the record of larger specimens from Waipipian Tahaenui Limestone on Mahia Peninsula.» BEU, A. G. 1995. Pliocene Limestones and their scallops. Lithostratigraphy, pectinid biostratigraphy, and paleogeography of eastern North Island late Neogene limestone. Institute of Geological & Nuclear Sciences Monograph 10. Institute of Geological and Nuclear Sciences, Ltd., Lower Hutt, New Zealand, 243 p. [p. 48, 50]
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Towaipecten ongleyi (Marwick); A. G. Beu, 1995, Pliocene Limestones and their scallops, figures 15c, d.
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«Small to moderately large for genus (64-100 mm high), most specimens equidimensional or slightly longer than high, obliquely elongate posteroventrally; left valve moderately more inflated than right; ears moderately large, almost equal in 2 valves, anterior moderately to markedly longer than posterior, with wide, shallow, but obvious byssal sinus at base of right anterior ear, but no etenolium in adult. Sculpture of 25-36 (about 30 on most specimens) low to prominent, narrow, closely spaced radial costae, equal in width on 2 valves, those on left valve bearing 3 low, narrow costellae on their surfaces in most advanced (late Opoitian) populations; I secondary costella in all interspaces on left valve, secondary costellae absent from some right valves. Internal features unknown.
Opoitian; Opoiti Limestone, tributary of Kaikoura Stream three km east of Tiniroto-Gisborne Highway, northeast of Tiniroto, northern Hawke's Bay (type); particularly abundant in Opoiti and Whakapunake Limestones in Northern Hawke's Bay; also abundant in Te Aute limestone facies and in near-shore sandstone facies in Wanganui basin, South Taranaki, the northern Ruahine Range, and throughout the eastern North Island from Gisborne (Ormond Limestone) to southern Wairarapa (limestone on the Aorangi Range). The smaller size and the more oblique disc distinguish Phialopecten ongleyi from its apparent successor P. marwicki (PI. 33a), and the larger size, less marked obliquity, and coarser ribbing distinguish it from the apparently ancestral P. tolagaensis (Kapitean, Tokomaru Sandstone fades of Tolaga Bay to Anaura Bay, north of Gisborne) (height 27 to 61 mm). Statistical reassessment in long sequences is under way to more certainly distinguish P. ongleyi from P. marwicki, as these are the most useful indices of the Opoitian and Waipipian stages in the widespread Te Aute limestone facies of eastern North Island, but the lineage appears to have increased maximum shell size very gradually through Opoitian and Waipipian time. Figured specimen (PI. 33e): GS11886, R21/f01, Larsen shellbed, north of road end, Waitotara Valley, Wanganui basin, Opoitian (NZGS) x 0.67.» BEU, A. G. & P. A. MAXWELL. 1990. Cenozoic Mollusca of New Zealand. New Zealand Geological Survey Paleontological Bulletin, 58: 1-518, pls. 1- 57. [p. 276]
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Phialopecten ongleyi Marwick; A. G. Maxwell & P. A. Maxwell, 1990, Cenozoic Mollusca of New Zealand, plate 33, figure e.
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