Dietotenhosen Santelli & del Río, 2019
SANTELLI, M. B. & C. J. DEL RÍO. 2019. New Neogene taxa of the tribe Chlamydini Teppner, 1922 (Pectinidae, Bivalvia) of southern South America. Journal of Paleontology, 93 (6): 1088-1104, figs. 1-7. [p. 1090]
«Dietotenhosen new genus
Type species.— Pecten hupeanus Philippi, 1887 (= Pecten vidali Philippi, 1887), La Portada, Bahía Inglesa, Coquimbo and Horcón formations, Chile; Pisco, Huaricangana, Taime, and Hornillos formations, Peru.
Other included species.— Dietotenhosen remondi (Philippi, 1887) (= Pecten coquimbensis Möricke, 1896) from Bahía Inglesa, Coquimbo and Horcón formations, Chile.
Diagnosis.— Shell as high as long in adults, left valve being strongly more convex than right one. Umbonal angle 99–116°. Byssal notch moderately deep, auricles long and quite symmetrical for the tribe, with free margins of posterior auricle convex or straight. Left valve sculptured with 17–22 plicae, 18–26 plicae on right valve, plicae are rather uniform width and ornamented with 3 or 4 ribs that appear at 40–60 mm from the beaks.
Occurrence.— Middle Miocene–early middle Pliocene from northern Peru to central Chile.
Etymology.— Dedicated to the German Rock Band “Die Toten Hosen.”
Remarks.— Dietotenhosen n. gen. is characterized by a large shell, subcircular or flabelliform in outline, usually opisthocline, highly inequiconvex with left valve nearly twice as convex than the right one, auricles quite symmetric in comparison with other Chlamydini, with free posterior margins convex or straight, and by the development of a moderately deep byssal notch. The valves are sculptured with evenly wide, rectangular or sub-rounded plicae in crosssection, bearing three or four ribs that appear at 40–60 mm from the beaks and with interspaces that are ornamented with a single central primary rib from 10–30 mm height on both valves and with secondary ribs that commence in late ontogeny.
Pecten remondi Philippi, 1887 and P. hupeanus Philippi, 1887 were placed by Herm (1969) in Chlamys sensu stricto Röding, 1798, but the presence of inequiconvex and larger shells than in Chlamys s.s., with less-inclined dorsal margins of discs, a wider umbonal angle, more symmetrical auricles with posterior freemargin convex or straight, a very shallow byssal sinus, and the development of conspicuous plicae (Figs. 3.12, 5.11) distinguish those taxa from Chlamys s.s. and group them into a new genus. Subsequently, Beu (1985) related D. hupeanus n. comb. and D. vidali with Psychrochlamys patagonica (King, 1832) (Recent, southern South American coasts) and with Moirechlamys actinodes (Sowerby, 1846) (late Miocene, Patagonia). Finally, Jonkers (2003) stated that C. remondi and C. hupeana would belong in Zygochlamys Ihering, 1907. However, the representatives of Dietotenhosen n. gen. have outstanding differences with the southern genus Zygochlamys (type species: P. geminatus Sowerby, 1846, late Oligocene–early Miocene, San Julián and Monte León formations) in possessing sub-circular or flabelliform shells with opisthocline discs, wider umbonal angles, a more flattened right valve, auricles markedly more symmetrical, with longer posterior ones having a convex or straight free margin, lower left anterior auricle, and shallower byssal notch and sinus. In addition, Chilean taxa are sculptured with plicae of almost uniform width that are unpaired on the right valve. Ribs on both valves are covered with lower scales, secondary and tertiary ribs on interspaces appear later in ontogeny, and left interspaces are narrower than the plicae (Table 1). Dietotenhosen n. gen. has flabelliform and sub-circular shells like the Patagonian genus Moirechlamys (type species: P. actinodes Sowerby, 1846, late Miocene, Puerto Madryn, Gran Bajo del Gualicho and Barranca Final formations and “Cape Fairweather Beds;” Santelli and del Río, 2019; figs. 9.2–9.4, 10), but the new genus has more-flattened right valves, more-symmetrical auricles, with a higher right anterior auricle, left anterior and posterior auricles sculptured with fewer ribs and with shallower sinus and byssal notch. Moreover, shells are sculptured with fewer and sub-equally wide plicae (Table 1).
Psychrochlamys Jonkers, 2003 is differentiated from Dietotenhosen n. gen. by the lack of shagreen microsculpture and the development of coarse commarginal lamellae over the entire surface. In addition, Psychrochlamys has orbicular shells with symmetrical and short auricles, with a shallow byssal notch, and free margin of left anterior auricle sloping posteriorly.» MARÍA BELÉN SANTELLI & CLAUDIA JULIA DEL RÍO, 2019
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Dietotenhosen hupeanus (Philippi, 1887) n. comb.; M. B. Santelli & C. J. del Río, 2019, New Neogene taxa of the tribe Chlamydini Teppner, 1922 (Pectinidae, Bivalvia) of southern South America, figure 3.
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