Spondylus mimus Dall, Bartsch & Rehder, 1938
DALL, W. H., P. BARTSCH & H. A. REHDER. 1938. A manual of the Recent and fossil marine pelecypod mollusks of the Hawaiian Islands. Bernice P. Bishop Museum Bulletin, 153: i-iv, 1-233, pls. 1-58. [p. 102, pl. 26, figs. 6, 7]
1938 Spondylus mimus Dall, Bartsch & Rehder, 1938
1938 Spondylus kauaiensis Dall, Bartsch & Rehder, 1938
1938 Spondylus kauaiensis Dall, Bartsch & Rehder, 1938
W. H. Dall, P. Bartsch & H. A. Rehder, 1938, plate 26.
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«Shell small, subcircular, crystalline sugary white with broad, concentric, brown bands on the central area, between which the shell is brilliantly rose colored. The spines are also rose colored, furnishing a very marked pattern. Prodissoconch of the upper valve worn, showing, however, at its ventral margin, radiating threads. The post-prodissoconch stage shows 12 major radiating ribs which are heavily spined, the spines being rather distantly placed and are concave on their ventral side. Between these, medially, another thread is present which is also spined and between this and the heavy radiating ribs still finer threads are present, which vary in number from two to five. These lesser threads are granulose but not spinulose. The wings are marked by fine wavy radiating threads which are not spinose, and the area on the lateral margin along side of these bears numerous fine threads, equaling those on the wings. In addition to this, there is a still finer microscopic sculpture which consists of exceedingly fine lirations which are present on the ribs and the spaces between them, and which in the middle of the disk are vertical, while on the edges they assume an outward slant. The inside of the upper valve is white with a reddlish flush, its lateral and ventral margins slightly scalloped and fluted at the edge. The interior shows the radiating ribs of the outside as light zones. The ligamental area is rather narrow and denticulated at the ventral margin. The hinge consists of the two low median teeth bordering the resilial pit, the deeper impressed pits to accommodate the larger teeth of the ventral valve and then two rather narrow, strong and decidedly hooked teeth. The margins ofi the deep pits separating the resilial teeth from the outer teeth are strongly denticulated. The two wings also show a number of transverse folds suggesting denticulations. The lower valve, wich is not described from the type but another specimen, U.S.N.M. Cat. No. 484164, has the tip of the prodissoconch hemispherical and the succeeding part flattened, showng only ligamental lines and microscopic radial striations on the outside, but on the inside 12 radliating ribs. The early post-prodissoconch stage, in fact all the parts that play a role in attachment. are marked with concentric lamina which slant ventrally. The spaces between the lamina may be spinose, the spines being long and slender where present, andl there is also a very fine microscopic, concentric and radiating sculpture present. The upturned portion of the lower valve is marked by a few strong radiating threads, which bear strong red and yellow tipped spines and between which finer spinose rows are present as in the upper valve, and still finer granulose threads between these and the strong threads. The inside of the lower valve is white and also shows the radiating zones referred to in the upper valve. The ligamental area is very broad, transversely threaded and longitudinally striated, and medially obliquely slit. The hinge bears two strong recurved teeth immediately outside of the ligamental pit and two lesser teeth on the lateral margin, separated by a broad pit. The upper portion of the hinge line is denticulated. The outer edge of the lower valve is also feebly scalloped and fluted.
The type, U.S.N.M. Cat. No. 337509, an Llpper valve, was collected by Thaanum in 13 fathoms at the entrace to Honolulu Harbor, Oahu.
U.S.N.M. Cat. No. 484164, a lower valve, was dredged by the U. S. Bureau of Fisheries Steamer Albatross at Station 3847 off the south coastof Molokai in 23-24 fathoms on sand and coral bottom. The latter has served for our description of the lower valve. The type measures: height, 20.3 mm.; length, 21.4 mm; diameter, 6.1 mm. This species is one of two that we have seen from the Hawaiian islands in which the wings are not spinose; the other is Spondylus kauaiensis. The present form will be at once distinguished from that by its brilliant color and also by the fact that it has 12 major radiating ribs instead of nine.» WILLIAM HEALEY DALL, PAUL BARTSCH & HARALD ALFRED REHDER, 1938
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«Dijkstra and Marshall (2008: 74) treated Spondylus asperrimus G.B. Sowerby II, 1847, from Norfolk and Kermadec Island, and synonymized several Hawaiian species of Dall et al., 1938, notably S. mimus, S. gloriosus and S. kauaiensis.
Spondylus gloriosus however, is a characteristic Hawaiian species, well known under its former, erroneous name “S. linguafelis” (Huber, 2009). Spondylus gloriosus is also known from offshore Panamic Islands, but does not live in waters of Norfolk or Kermadec Islands (Huber, 2009: 107, fig. 11; Huber, 2010: 216, fig. 1; Severns, 2011: 456, pl. 208, fig. 4). Although we agree that the Hawaiian S. mimus and S. kauaiensis are conspecific, we do not concur with them being synonymized with S. asperrimus which is another characteristic species and well known from the Philippines and Australia. Neither the juvenile holotype of S. kauaiensis (Figs. 20 E–F) nor the adult S. mimus have any resemblance to S. asperrimus. Furthermore, nothing similar to the type material of S. asperrimus, housed in Natural History Museum of London, has ever been seen from the Hawaiian Islands (see Huber, 2010: 216, figs. 2 and 3; Severns, 2011: pls. 207–209).» RAINES, B. K. & M. HUBER. 2012. Biodiversity Quadrupled—Revision of Easter Island and Salas y Gómez Bivalves. Zootaxa, 3217: 1-106, figs. 1-49. [p. 42]
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A–D, Spondylus aff. mimus Dall, Bartsch & Rehder, 1938; E–F, Spondylus kauaiensis Dall, Bartsch & Rehder, 1938, (Holoytype, USNM 335638); B. K. Raines & M. Huber, 2012, Biodiversity Quadrupled—Revision of Easter Island and Salas y Gómez Bivalves, figure 20.
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«Kay (1979) added S. kauaiensis Dali, Bartsch & Rehder, 1938, as a synonym of S. gloriosus. However, I do not agree with the additional synonym S. mimus Dall, Bartsch & Rehder, 1938. Spondylus mimus is regarded here as an uncommon, rather small, but valid species, as depicted by Severns (2000: 236) under “S. nicobaricus” from Hawaii.»
HUBER, M. 2009. Name changes for the two well-known Panamic spondylids. The Festivus, 41 (7): 103-109, figs. 1-12. [p. 107]
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