"Chlamys" trilirata (Almera & Bofill, 1897)
ALMERA, J. & A. BOFILL. 1897. Monografía de las especies del género Pecten del Burdigalense superior y de una Lucina del Helveciense de las provincias de Barcelona y Tarragona. Memorias de la Real Academia de Ciencias y Artes de Barcelona, 3ª época, 1 (20.2): 395-408, pls. 1-7 (2ª ed., Establ. Tipog. de Jaime Jepús y Roviralta, Barcelona). [p. 401, pl. 4, figs. 6, 6a]
J. Almera & A. Bofill, 1897, plate 4.
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«Testa ovato-oblonga, aequilatera, convexiuscula, longitudinalitèr 16-17 costata; costae medianae planiusculae, Iatae, ad marginem bisulcatae, undè triliratae; laterales angulosae et angustiores, ad marginem bifidae; interstitia versùs marginem unicostulata, caeterùm in costis medianis angustiora, in lateralibus subaequalia; auriculae minimae radiatìm costulatae, costulis margini laterali subparalellis.
Molasa de Bará.»
JAIME ALMERA & ARTURO BOFILL, 1897
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«Description: Chlamydoid shell is small (maximally 22 cm in length), higher than long with length/high-ratio ranging between 0,88 and 0.93, biconvex, moderately arched, valver are thin and outside the palial line translucent, discs both posteroventrally elongated with rounded posterior and ventral margins and pointed anterior and dorsal margins, umbonal angles ranging between 83 and 90º. The right valve with 18-19 ribs, the left one with 17 ribs; on both valves ribs mederately prominent, wider than interspaces convex to subtriangular, initiated non-synchronously (the subsequent ones by intercalation) between shell height of 0.7 and 2 mm. At shell height of about 10 mm a single riblet can intercalate the interspaces of the lateral region, at shell height of about 20 mm three riblets on rib tops and one in each interspace become initiated on the central disc region, the riblets can develop coarse scales on tops. Ears large, pointed and about two times longer anteriorly, truncated posteriorly, up to 5 riblets can sculpture each one. Active ctenolium with fine denticles, and deep byssal synus present. Exterior typically sculptured by shagreen microsculpture present on the whole shell or reduced to its parts as in morphs with transversal bars developed on rib tops. The smooth parts bear commonly Camptonectes-type microsculpture. Interior with internal ribs lining the interspaces and missing the rib carinae. Hinge region very narrow with reduced dentition and shallow, triangular resilial pit.
Variation: The strong morphological variation typical of this species (cf. Mandic & Harzhauser 2003) is expressed in the prominence of ribs and riblets and in the development of the shagreen microsculpture that can be almost completely absent. The transversal bars on rib tops are also rarely present. Normally the weaker radial sculpture is followed by reduced shagreen microsculpture. The transitional character of this variation is documented by a sample from the Middle Miocene of Boujan in S-France including more than 40 specimens and housed in the Roger (1939) collection.
Remarks: As noted by Mandic & Harzhauser (2003) investigations of the type material haused at the Type Collection of the Department of Earth Sciences, Claude Bernard University Lyon proved types mof "Chlamys" triliratus and "Chlamys" bryzodermis (Almera et Bofill) for the left and the right valve same species. Roger (1939) correctly classified the latter specimen together with the specimens from the Lower Badenian of the Gaindorf Formation. Yet as he erroneously held them for the topotypes of Chlamys jakloweciana (Kittl) he applied the latter name to all those specimens. The mistake was detected and partly revised by Shultz (2001). Hence Chlamys jakloweciana is not only restricted to the Early Miocene, but also differs by distinctly larger size, more massive shell and numerous but more prominent ribs with a different sculptural pattern. The large left valve from the Badenian of Sievring being a part of the Chlamys jakloweciana original type series also differs from the Eggeburgian representatives (cf. Schultz, 2001). According to the arrangement and trigonal shape of ribs it appears to be related to Chlamys justiniana (Fontannes).
Chlamys jakloweciana indicated by Kautsky (1928) from the Karpatian (Late Burdigalian, Early Miocene) of Stetten/Korneuburg (NE Austria) is a erroneus identification of Aequipecten fragments previously published by Glaessner (1926) as Pecten (Chlamys) sp. nova. The lot bearing an indentical inscription written by Glaessner (per. com. Harzhauser, Viena), but also "Chlamys jakloweciana Kittl, Dr. Kautsky det." is haused in the Locality Collection of the Geological Department — Natural History Museum Viena. As pointed out by Waller (1993) the shangreeen microsculpture is a feature unique to Chlamys-related pectinids. Thus among other typical features like hinge and commarginal lamellae shape, especially the presence of shangreen microsculpture do not allow classification of "Chlamys" triliratus with Aequipecten (cf. Waller 1991). However, its morfology also differs importantly from the representatives of Chlamys s.s. (cf. Waller 1993). hence the genus is provisionally referred to as "Chlamys".» MANDIC, O. 2004. Pectinid bivalves from the Grund Formation (Lower Badenian, Middle Miocene, Alpine-Carpathian Foredeep) - Taxonomic revision and stratigraphic revision. Geologica Carphatica, 55 (2): 129-146, figs. 1-7. [p. 135, 136]
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"Chlamys" trilirata (Almera et Bofill); O. Mandic, 2004, Pectinid bivalves from the Grund Formation (Lower Badenian, Middle Miocene, Alpine-Carpathian Foredeep) - Taxonomic revision and stratigraphic revision, figures 4.1-4.5.
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