Chokekenia Santelli & del Río, 2019
SANTELLI, M. B. & C. J. DEL RÍO. 2019. Neogene Pectinidae (Bivalvia) of tribe Chlamydini Teppner, 1922 in Patagonia (Argentina): Zygochlamys Ihering, 1907 and three new genera. Journal of Paleontology, 93 (2): 312-336, figs. 1-11. [p. 325]
«Chokekenia new genus
Type species.— Zygochlamys nicolasi Morra, 1985. Early Miocene, San Julián and Monte León Formations, bymonotypy.
Diagnosis.— As for type species.
Occurrence.— Early Miocene of southern littoral of the Golfo de San Jorge and of northern and southern sectors of the Austral Basin.
Etymology.— From the word chokeken, which in the language of the Tehuelche native tribe means “plateau,” in reference to the growth ledges on the shells.
Remarks.— Chokekenia n. gen. is here defined to include the Miocene species C. nicolasi n. comb. (Morra, 1985), characterized by having few plicae that are paired on right valve and being a monospecific genus clearly differentiated from the genera described so far.
Chokekenia n. gen. is distinguished from Zygochlamys by its shells with orbicular outlines, one ledge, a wider umbonal angle, more symmetrical auricles (Fig. 8.3, 8.4, 8.6, 8.7), and narrower plicae covered with finer ribs of equal width that bifurcate twice on right plicae. Moreover, the ribs are sculptured with scales that appear at 20–40 mm shell height, and left interspaces are narrower than plicae, whereas in Zygochlamys scales appear earlier in ontogeny and interspaces are wider than the plicae. Chokekenia n. gen. can be separated from Swiftopecten because it has a wider umbonal angle and a shorter hinge margin, and shells are sculptured with more plicae without nodes and with fewer ledges, covered with fewer scaly ribs. Chokekenia n. gen. is differentiated from Semipallium Jousseaume in Lamy, 1928 (type species: Pecten tigris Lamarck, 1819 [= Semipallium flavicans {Linnaeus, 1758}], Recent, Indo-West Pacific; Dijkstra, 2013, fig. 22, 1a–d) in having plicae entirely subdivided and bifurcated and arranged in conspicuous pairs, larger posterior auricles, and a deeper byssal notch. The Patagonian genus also has shagreen microsculpture always restricted to the umbonal area, whereas in Semipallium it extends over the entire disc. Chokekenia n. gen. is particularly similar to Semipallium hallae (Cotton, 1960) (Recent, between Adelaide and Glenelg, South Australia; Dijkstra and Beu, [2018] figs. 84 g–h, 86a–c) in having shells sculptured with ribs of homogenous size. In addition, the Australian species has an incipient bifurcation on some right valve plicae.» MARÍA BELÉN SANTELLI & CLAUDIA JULIA DEL RÍO, 2019
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Chokekenia nicolasi (Morra, 1985) n. comb; M. B. Santelli & C. J. del Río, 2019, figures 8.1-8.7.
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