Semipallium hallae (Cotton, 1960)
COTTON, B. C. 1960. A new species of scallop Notochlamys hallae sp. nov. from South Australia. Royal Society of South Australia Malacological Section, Publication, 14: 2 p. (unnumbered). [(1), 2 figs. unnumbered]
1960 Notochlamys hallae Cotton, 1960
Semipallium hallae (Cotton, 1960); B. K. Raines & G. T. Poppe, 2006, A Conchological Iconography, The Family Pectinidae, plate 185, figure 3.
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«Slightly inequivalve, inequilateral, higher than long; about nine principal but weakly defined radial ribs on each valve slightly less defined than those of the left. Radial ribs on both valves are very much cut up into radial riblets, but they continue to the umbo; principal ribs weakly defined internally; auricles very unequal, byssal gape large, pectinidal teeth almost obsolete in mature shells. The colour is white in the umbonal area then light violet and finally violet. Holotype: Australia, SA, Largs Bay, alive, length 47 mm., height 51 mm. Hall Collection.»
BERNARD CHARLES COTTON, 1960
[fide B. K. Raines, B. K. & G. T. Poppe, 2006] |
«Type data. Holotype (pr) SAM D16541. Type locality: South Australia, Largs Bay, Semaphore Beach.
Comments on type data. The listed and figured articulated paratype (H 50 mm, W 44 mm) is not in the SAM collection, but is possibly in the Hall collection.
Additional material examined. —AUSTRALIA: SOUTH AUSTRALIA: Yorke Peninsula, Edithburgh Jetty, alive, 4–5 m (1 pr, SAM D19012); Adelaide, West Beach, c. 34°56'S 138°36'E, dead, beach (1 v, WAM S12924); Gulf of St Vincent, Port Adelaide, Outer Harbour, alive, 5 m (3 pr, SAM D19013); Gulf of St Vincent, Henley Beach, dead, beach (2 v, SAM D19014); offshore from Glenelg, 34°59'S 138°31'E, low limestone reef, alive (1 pr, ZMA Moll.146627).
Description. Shell up to c. 55 mm high, weakly inflated, almost equally convex, elongate, somewhat higher than wide, slightly inequivalve and inequilateral, anterior auricles larger and longer than posterior, umbonal angle c. 95°; most specimens purplish, umbonal area paler; right valve paler; interior deep purplish.
Both valves sculptured with 8–9 evenly spaced, weakly defined primary radial plicae (narrower on left valve, wider on right valve), less prominent towards anterior and posterior ends of disc; secondary radial riblets present on plicae (c. 3 on left valve, 4 on right valve) and in radial interspaces. Interstitial shagreen microsculpture throughout. Anterior auricles bearing c. 7–10 radial riblets, posterior bearing 4–6. Dorsal margin straight. Byssal notch moderately deep, byssal fasciole rather broad. Functional ctenolium weakly developed, with c. 6 teeth, or almost obsolete in mature stage. Internal corrugations well-defined, corresponding to external radial plicae; edges sharply defined, carinate around ventral margin. Hinge with prominent resilial and dorsal teeth. Dimensions. Illustrated specimen: SA, offshore from Glenelg, 34.9667°S 138.5167°E, low limestone reef (ZMA Moll.143774): H 48.6, L 49.4, D 15.2 mm.
Habitat. Living in the littoral zone in crevices of limestone ledges at silty reef edges, hidden in shallow areas amongst rubble, and byssally attached to hard substrates.
Distribution. This species has a very limited distribution in South Australia, in particular in the Gulf of St Vincent. Present specimens alive at 4–5 m.
Remarks. Cotton (1960) placed this little-known species in Notochlamys Cotton, 1930, based mainly on the shagreen microsculpture. However, Semipallium hallae differs from Notochlamys species in several characters: more elongate in shape (Notochlamys more nearly circular), less clearly defined primary radial plicae (well-defined in Notochlamys), and great reduction in the size of the posterior auricles (in Notochlamys the anterior and posterior auricles are of almost identical size). Semipallium hallae is more appropriately placed in Semipallium.
Beu & Darragh (2001: 76) synonymized Semipallium hallae with S. aktinos (Petterd, 1886) with a query, having seen no material of this very restricted species. In our opinion the two are distinct and differ in the larger size, wider shape, more prominent radial plicae, and more uniform purplish colour of S. hallae than of S. aktinos.» DIJKSTRA, H. H. & A. G. BEU. 2018. Living scallops of Australia and adjacent waters (Mollusca: Bivalvia: Pectinoidea: Propeamussiidae, Cyclochlamydidae and Pectinidae). Records of the Australian Museum, 70 (2): 113-330, figs. 1-102. [p. 267, 268]
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Semipallium hallae (Cotton); H. H. Dijkstra & A. G. Beu, 2018, Living scallops of australia and adjacent waters, figures 82G, 82H, 84A–84C.
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«Slightly inequivalve, inequilateral, higher than long; about nine principal but weakly defined radial ribs on each valve slightly less defined than those of the left. Radial ribs on both valves are very much cut up into radial riblets, but they continue to the umbo; principal ribs weakly defined internally; auricles very unequal, byssal gape large, pectinidal teeth almost obsolete in mature shells. The colour is white in the umbonal area then light violet and finally violet. Holotype: South Australia, Largs Bay, alive, length 47 mm., height 51 mm. Hall Collection. Fig. 85.
Remarks: The paratype measures 44 mm. x 50 mm. The spccies is named after Mrs. R. A. HaIl who in company with her husband, a keen collector and secretary of the Malacological Section of South Australia, found four specimens of this new scallop alive, two washed up on the beach and two in shallow water, on August 24th, 1959, Largs Bay.
Mr. A. Stokes found a single valve at the same locality. Later Mrs. P. Baack showed to me a speeimen taken alive in shallow water, again at Largs Bay. This specimen is dark yellow coloured changing to dark brown towards the margin; interior reddish lilae blotched with green and yellow. The nearest species to N. hallae is N. tasmanicus Adams and Angas 1863, a Peronian shell, type locality east coast of Tasmania, odd dilapidated specimens of which have been rarely taken in South Australia. N. hallae is a quite distinct narrower sheil with practically similar sculpture on each valve and there are no bold well-separated major radial ribs so characteristic of N. tasmanicus. A series of the Tasmanian shell from the May collection sholvs the marked difference in the species. Another distinguishing feature is the great reduction in the size of the smaller auricle. N. hallae has the fine shagreen sculpture of Notochlamys Cotton 1930 as distinct from the concentric threads of Mesopeplum Iredale 1929.» COTTON. B. C. 1961. South Australian Mollusca. Pelecypoda. W. L. Hawes, Government printer, 363 p., figs. 1-348. Adelaide, Australia. [p. 99, 100]
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