Austrochlamys Jonkers, 2003
JONKERS, H. A. 2003. Late Cenozoic-Recent Pectinidae (Mollusca: Bivalvia) of the Southern Ocean and neighbouring regions. Monographs of Marine Mollusca, 5: i-viii + 1-125 pp, 17 pls. Backhuys Publishers, Leiden. [p. 59]
«Genus Austrochlamys gen. nov.
Etymology. From the Latin auster ('south') and the generic name Chlamys, thus combined since it both reflects the common name for A. natans in Chile, "ostión del sur" ('southern large oyster'), and the southern distribution of all members of this genus.
Type species. Pecten natans Philippi, 1845.
Diagnosis. Moderate- to large-sized (mean VH 50-100 mm; Fig. 41) chlamydoids with prosocline shells that change little in shape during ontogeny (Fig.42); disc nearly circular to highly asymmetrical (and then anterior part of disc longer than posterior part); umbonal angle 100º-120º; disc gapes not present in all species. Macrosculpture consisting of simple corrugations of the disc; costae low, main ribs sometimes of uneven width, never fasciculate. Prominent commarginal lamellae in rib interspaces. Microsculpture in pre-radial stage of LV and on disc consisting of low and wide antimarginal ridgelets; microsculpture on disc never shagreen (Plate 2, figs. a, c, e, Plate 3, figs. a-c). Outer ligament comparatively long; hinge and resilial teeth (if present) weak. No byssal sinus; byssal notch acute and deep. Functional ctenolium in all species.
Remarks. Austrochlamys differs from Zygochlamys and Psychrochlamys in having a prosocline shell, commarginal lamellae in rib interspaces throughout ontogeny, and a mostly acute rather than arcuate byssal notch (Fig. 29). Fasciculate ribs, as seen in the latter genera, do nor occur in Austrochlamys. Antimarginal microsculprure on the disc (if present) is much coarser than in Zygochlamys and Psychrochlamys.
StratigraphicaI range and distribution. Oligocene-Recent (Fig. 25). Fossil species are widely distributed in Antarctica; rare fossils occur on the Patagonian shelf and in sub-Antarctic New Zealand. A single Recent species occurs in southernmost South America (Fig. 28).
Included species. Austrochlamys gazdzichii sp. nov., Oligocene, King George Island, South Shetland Islands, A. marisrossensis sp. nov., Early Miocene, Ross Sea, A. heardensis (Fleming, 1957), ?Late Miocene, Heard Island, A. anderssoni (Hennig, 1911), Late Miocene-Late Pliocene, Antarctica, A. tuftsensis (Turner, 1967), Early Pliocene, Antarctica, A. natans (Philippi, 1845), comprising the Recent, southern South American A. natans natans and ?late Pleistocene A. natans walosseki subsp. nov., from South America and New Zealand.»
H. A. JONKERS, 2003
|
Austrochlamys natans natans (Philippi); H. A. Jonkers, 2003, Late Cenozoic-Recent Pectinidae (Mollusca: Bivalvia) of the Southern Ocean and neighbouring regions, plate 15, figures a, b.
|