Borehamia crawfordi (Hutton, 1873)
HUTTON, F. W. 1873. Catalogue of the Tertiary Mollusca and Echinodermata of New Zealand, in the collection of the Colonial Museum. Wellington, Government Printer, for Colonial Museum and Geological Survey Dept. xvi, 48 p. [p. 32]
1873 Pecten crawfordi Hutton, 1873
Mesopeplum crawfordi (F. W. Hutton, 1873); A. U. E. Boreham, 1965, A revision of F. W. Hutton's pelecypod species described in the Catalogue of Tertiary Mollusca and Echinodermata, plate 10, figures 1, 2.
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«Sub-orbicular, inequivalve, longer than high; right valve convex, with five or six broad plications, the central ones deep near the umbo, but all getting shallow towards the margin, with numerous radiating sub-scaly ribs, crossed by fine concentric striae; left valve compressed, flattened at the umbo, with four plications; exterior markings like the right valve; ears sub-equal, with radiating rugose ribs. Height, 2; length, 2.35.
Localities.— Maunga-pakeha Taipo, East Coast, Wellington.» FREDERICK WOLLASTON HUTTON, 1873
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«REMARKS: This large, distinctive, coarsely and consistently plicate species with small, square, almost equilateral and equivalve auricles is common in Waipipian rocks of a wide variety of facies - mudstone to Te Aute lithofacies limestone - and was accepted by Beu (1978) as a restricted Waipipian index species. Further collecting during the present project and re-examination of earlier records make it clear, however, that it definitely occurs at a few Opoitian localities.
A poor, distorted, incomplete specimen of M. crawfordi from the early Opoitian Ormond Limestone at Rimuhau Hill, Waerengaokuri (X18/f7552, GS 11493: see list in Appendix A) is the oldest specimen I am aware of. Other undoubted Opoitian specimens are from T24/f7325, GS 1310, conglomerate in Mangatoro Formation, Waitakotorua Strearn, western side of Waewaepa Range (see Appendix A) and Q20/f8484, GS 1218, Toko Road east of Straford, Taranaki (an atypical specimen with a prominent secondary costa in each primary interspace; occurs with common small P. marwicki). Also, closely similar but, very finely costate specimens occur in the early Opoitian Momoe-a-Toa Shellbed, Chatham Islands. This age assignment therefore removes the reliability of M. crawfordi as an index of Waipipian age for isolated localities whose age is not demonsraed by stratigraphy or by the occurence of other reliable pectinids. The two isolated localities for which the occrurence of M. crawfordi has previously seemed a guide to a Waipipian age, but for which an age younger than Opoitian can no longer be confirmed, are listed in Appendix A (under M. crawfordi, Opoitian): Maungaharuru Formation near Lake Opouahe, west of Lake Tutira (V19/f8529, GS 11306); and western Ruahine Range, near the summit of Te Rakaunuiakura (U21/f66, GS 14870).» 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. 54]
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Mesopeplum (Borehamia) crawfordi (Hutton); A. G. Beu, 1995, Pliocene Limestones and their scallops, figure 21b.
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«Large for genus (90-125 mm high), longer than high; right valve much more inflated than left; disc symmetrical and ears almost symmetrical, almost square, anterior ones retracted very slightly to disc, without byssal sinus or etenolium. Dorsal margins of disc long and lightly concave, diverging at a very high angle, producing a very strongly convex ventral margin. Sculpture of 5 major radial folds in disc, evenly and regularly folded on both valves, very prominent on dorsal half of disc but becoming weaker lower down, fading out before ventral margin of large shells; superimposed on folds are many prominent, wide, closely to widely spaced radial costae, highly variable in width, spacing and numbers of secondary costellae; in most specimens, costae are relatively wide, flat-topped, and closely spaced on right valve but narrow-crested and more widely spaced on left valve; on many specimens, margins of costae are finely serrated by fine commarginal threads. Hinge lacks cardinal crura. Valves meet at thickened, flat-faced, narrowly triangular facets on each side of resilifer, at a nodule at outer base of each ear (auricular crura), and around ventral margin of commissure, leaving narrow anterior and posterior gapes. Adductor scar moderately large (0.2 height of disc), oval; pallial line broad, simple; many small muscle scars around pallial line dorsal to adductor scar, and in a curved line just above adductor scar.
Waipipian; "Maungapakeha Taipo" (actually Mangapakeha hill, north of Taueru), east of Masterton, central Wairarapa (type); abundant and widespread in conglomerate, limestone, shellbeds and near-shore sandstone in Wanganui-South Taranaki (particularly at Waihi Beach, Hawera), Hawke's Bay, Wairarapa, Marlborough, and North Canterbury (particularly in Greenwood Formation in Lower Waipara Gorge near Greenwood's Bridge). A few doubtful records from Opoitian, but all appear to be an unnamed smaller, more coarsely ribbed species; one specimen from high in the type Nukumaruan sequence (Tewkesbury Formation) at Wanganui (reworked from Waipipian 1). The complete lack of a functional byssus in even juvenile shells confirms the evidence from relative valve inflation — Mesopeplum crawfordi is one of the group of pectinids that lies on its more inflated right valve, and has an "aerofoil" cross-section for sustained, active swimming to escape predatory starfish, and never lives byssally attached. Members of this group (like most pectens) live on current-swept "hard-grounds", where sediment will not clog their gills, as they lack a mantle cavity cleaning mechanism. The very much larger size, the few, very prominent radial folds, the prominent, wide radial costae, and the relatively small, almost square ears readily distinguish M. crawfordi from the more ubiquitous M. (Mesopeplum) convexum; earlier species (notably Waiauan, Tongaporutuan and Opoitian unnamed ones) of M. (Borehamia) are smaller than M. crawfordi, but are still larger than M. convexum. The much smaller Kapitean-early Opoitian M. (Borehamia) toaense has more subdued radial folds but much more prominent, square-edged radial costae than those of M. crawfordi; specimens of M. toaense are very rare in the Momoe-a-Toa Shellbed, Chatham Island (type) but common in limestone and shellbeds in southern Wairarapa and at Tolaga and Anaura Bays, north of Gisborne. Figured specimens (PI. 33f, g): GS5240, Q211f6501, Waihi Beach, Hawera, South Taranaki, Waipipian (NZGS) x 0.67 (2 separate valves).» 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. 278]
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Mesopeplum (Borehamia) crawfordi (Hutton); A. G. Beu & P. A. Maxwell, Cenozoic Mollusca of New Zealand, 1990, plate 33, figures f, g.
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«Boreham (1965, p. 33, pI. 10, figs. 1, 2) redescribed the species and figured both valves of the holotype. An excellent specimen from Waihi Beach, Hawera, collected by C. A. Fleming in January 1931, is figured here for comparison with M. hilli.
Boreham (1965, p. 33) discussed Hutton's type locality "Maunga-Pakeha Taipo", concluding that no Pliocene rocks were known in the taipos east of Mangapakeha Valley. This is confirmed by geological mapping of the district by Johnston (1975). Crawford (1863, p. 48), discussing the geology of the Taueru Valley, reported that "some very perfect "pecten", from the top of the Maunga Pakeha range, were presented to me by Mr Varnham, for the museum in Wellington". As they are referred to in the section on Taueru, and not later in the section of his report dealing with the taipos east of Tinui (second column p. 49), it appears that Crawford thought the specimens (presumably including the holotype of Pecten crawfordi Hutton) were collected from the low hills to the north-west of Taueru and Awatoitoi, which include Trig. Maungapakeha (grid ref. N158/383705, 1967 ed.). These hills include the Waipipian rocks known north of Taueru, and so the original type locality was probably correct, and confused by Hutton (1873, p. 32) with the taipos east of the Mangapakeha Valley. Therefore, the type locality can be accepted as being near Taueru, east of Masterton.» BEU, A. G. 1978. Taxonomy and biostratigraphy of large New Zealand Pliocene Pectinidae (Phialopecten and Mesopeplum). New Zealand Journal of Geology and Geophysics, 21: 243-269, figs. 1-30. [p. 261]
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Mesopeplum (Borehamia) crawfordi (Hutton,
1873); A. G. Beu, 1978, Taxonomy and biostratigraphy of large New Zealand Pliocene Pectinidae (Phialopecten and Mesopeplum), figure 3. |