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|Morphology||Ecology and taphonomy||External Literature Search||Age range and collections|
Bivalvia - Pectinida - Streblochondriidae
If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
|J. W. Busanus and R. D. Hoare 1991||Streblochondria with broad, low, radiating costae on both valves; costae crossed by slightly smaller, low, rounded, comarginal ridges, more prominent on right valves.
Right valve subcircular, slightly higher than long, with margins in ventral half nearly equally convex; hingeline shorter than valve length; posterior auricle with broadly obtuse marginal angle, separated from shell body by distinct sulcus; anterior auricle more distinct, separated from shell body by deep, pronounced sulcus; shell body with numerous, closely spaced, low, rounded costae crossed by slightly narrower, closely spaced, low, faint, comarginal ridges giving a reticulate appearance; anterior auricle with pronounced comarginal lamellae; posterior auricle with growth lines.
Left valve narrower and more elongate in appearance than right valve; hingeline short; ornamentation similar to right valve but less pronounced; both auricles with growth lines only.
Streblochondria tiltoni is easily distinguished from other species of the genus by the presence of the low, rounded costae crossed by low rounded ridges on both valves. One specimen of a right valve, believed to belong to this species (Figure 4.19), has an essentially smooth shell, which would indicate significant variation in the development of the ornamentation.
This species is most closely related to Streblochondria simpliciformis (Girty, 1927) in terms of overall size of shell and lack of well-developed surface ornamentation. It differs from Girty’s species in having a less convex posterior margin and the presence of radial and transverse ornamentation. Streblochondria similis (Walcott, 1884) and S. tenuilineata (Meek and Worthen, 1860) are larger, more ovate, and have much stronger ornamentation than S. tiltoni.