Genus Argyrotheca Dall, 1900 |
[Type-species = Terebratula cuneata Risso, 1826, p. 388 ] Small, commonly transversely ovate with wide hinge line but outline variable; ventribiconvex, smooth to more commonly multiplicate; beak short, subtruncate; foramen large, commonly hypothyrid; deltidial plates narrow. Pedicle collar well developed, supported by long, narrow, median septum. Cardinal process short, transversely elongate, buttressed by long, high, thick median septum; crura widely separate, short, prominent, pointed; loop long, formed of 2 slender, arcuate descending branches attached to base of crura, valve floor, and anterior end of median septum; short septal flanges present in adult stages; lophophore large, schizolophous, spicules not observed. Upper Cretaceous (Maastrichtian) - Present Diagnosis from volume 5 of the Occurrences: cosmopolitan. |
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Only fossil species:
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Diagnosis Diagnosis Diagnosis Diagnosis Diagnosis Diagnosis Diagnosis |
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Type locality: "régions coralligènes" - off Nizza. Terebratula cuneata Risso, 1826 p. 388 Diagnosis from Risso (1826) T. Testa glabra, rotundata, superne truncata; valvis ambabus costis latis, depressis, divaricantibus, longitudinaliter striatis sculptis; lateribus rotundatis ; epidermide lutescente, radiis ruberrimis. |
Argyrotheca cuneata: in about 15 m depth at Tarrafal, northwestern coast of Sao Tiago Island (Cape Verde Islands). Copyright © Peter Wirtz - identification by Alan Logan. |
Argyrotheca cistellula (Wood, 1841) Type locality: "Coralline Crag of Sutton, near Woodbridge in Suffolk" - Pliocene. Terebratula cistellula Wood, 1841, p. 253 No original Diagnosis |
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Argyrotheca jacksoni Cooper, 1973 Type locality: a reef cave at Ras Muhammad, S Sinai peninsula, 10 m. Argyrotheca jacksoni Cooper, 1973 p. 17. Diagnosis from Cooper (1973) Small yellow-gray Argyrotheca, with rectangular dorsal valves with about 11 costae. |
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Argyrotheca somaliensis Cooper, 1977 Type locality: Anton Bruun Cruise 9, station 447, 10°00'N, 51°15'E, 59-61 m.
Diagnosis from Cooper (1977) Small coarsely costate Argyrotheca, rectangular in outline with well-formed delthyrium and scalloped anterior margin. |
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Argyrotheca cooperi Bitner et Logan, 2013 Type locality: Suakin Archipelago, Sudan, 18° 57’N, 38° 15’E, at 90m. Diagnosis from Bitner & Logan (2013) Small Argyrotheca with a wide hinge line and 4-6 heavy rounded ribs, producing scalloped anterior margin. |
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Argyrotheca angulata Zezina, 1987 Type locality: St. BENT.06DR, Benthedi cruise, off Glorieuses Is., France (Mozambique Channel), depth 500-460 m. Diagnosis from Zezina (1987) Shell : small, white, widely transverse (length of pedicle valve 2.1 mm, length of brachial valve 1.6 mm, width of shell 3.3 mm). Shell surface : almost smooth, but faintly faceted with two feeble ridges on each half of the valve ventrally and dorsally, middle ridges beeing moved aside (the middle ridges are stronger than the lateral ones). Tall area : inclined 45° to the plane of the shell, striated transversly. Deltidial plates : narrow, triangular, stretched out along the sides of rectangular hypothyrid open foramen which does not reach the umbo of pedicle valve. Pedicle collar: horizontal, flat and wide, grown together with the septum in its posterior half. Pedicle : short and flat, its attaching surface forming a brush of short filaments. No crura; descending branches of brachial loop attached posteriorly to the front of socket ridges and anteriorly to the back surface of pyramid-shaped septum; posterior part of the septum near the umbo forms a cavity for a brood pouch. |
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Argyrotheca furtiva Simon, 2010 Type locality: shipwreck "Mutiara", Bay of Palu, off Donggala Harbour, Sulawesi, Indonesia, at 30m. Diagnosis from Simon (2010) Small, thick, ventribiconvex shell, subpentagonal in outline with obtuse wing-like lateral extremities, lenticular in lateral profile. Four radial incipient costae on either valve in opposite folding. Shell surface regularly tuberculate under SEM examination. Rectimarginate anterior commissure and sinuous lateral commissure. Large pedicle collar not buttressed by the low blade-like ventral septum, which extends for two-thirds of the valve length. Obtusely pointed crural processes. Weakly defined descending branches fused up to the mid-valve with valve floor and raised on the lateral slopes and the posterior part ofthe dorsal septum. Dorsal septum rather low, narrowly subtriangular in lateral profile with anterior slope straight, not serrate nor tuberculate. Strong adductor muscles scars developed in the posterior part of the dorsal valve with one large ptmcta present on either internal side of these scars. |