45 out of a total of 55 specimens of a second isopod species were found still in situ inside rhizomes, indicating that this isopod may also utilize seagrass as a source of food. This is most probably also the case with the polychaete, the echiurid and one isopod species, as other specimens of these three species were found to feed on other kinds of plant material (of terrestrial origin). It is certain that at least the gastropod feeds on the marrow of the rhizomes. A total of nine different, hitherto underscribed species were found inside Thalassia rhizomes (viz., a polychaete, an echiurid worm, a cocculinid gastropod, and six species of isopods). Fresh traces of gnawing activity on rhizomes and blades are abundant. Eight or nine kinds of sessile animals (including large protozoans, actinians, gastropods, and a tanaid crustacean) have used blades and/or rhizomes as a substrate. Recent American photographic surveys of the deep-sea floor off the east coast of the United States and in the Caribbean have shown the occurrence of a sometimes large number of seagrass blades, particularly after hurricanes.Examination of considerable quantities of seagrass (mainly Thalassia testudinum Banks ex König) collected in 1973 by the Soviet R/V Akademik Kurchatov has revealed extensive. Six new combinations are proposed: Ennucula kokozuraensis (Hatai and Nisiyama, 1949), Parvamusium tochigiense (Kanno, 1961), Semipallium crassivenium (Yokoyama, 1929), Securella yokoyamai (Makiyama, 1927), Phacosoma hataii (Masuda, 1963) and Parilimya kawadai (Omori, 1952).
A new subgenus, Chlamys (Nomurachlamys), and three new species, SaccellaĪnnakensis, Limopsis nodai and L. A total of 122 species and subspecies of marine bivalves belonging to 78 genera are discriminated from the Middle to Upper Miocene sequences in the Annaka-Tomioka area, Gunma Prefecture (Tomioka and Annaka Groups), the Karasuyama area, Tochigi Prefecture (Arakawa Group), the Iwadono area, Saitama Prefecture (Tokigawa Group) and some other areas. This paper presents a systematic study of fossil marine bivalves from Middle to Upper Miocene deposits in the northern Kanto region, central Japan, as the basis of a better understanding of Neogene molluscan faunal changes in the Japanese Islands. Because mouthparts that are usually used to make familial and generic assignments are not preserved, traditional systematic methods are combined with a multivariate principal coordinate analysis, as well as ecological and paleontological considerations to evaluate the most likely affinity of the fossil isopod. The high reactivity of the enclosing volcanic ash set the stage for unique and variable taphonomic conditions with some skeletal elements being preserved in high resolution, whereas others were completely obliterated by the formation of large crystals of secondary zeolites. It is preserved in a concretion that was formed in a glass-rich volcanic ash deposited into a shallow epicontinental seaway. The new taxon is represented by a single specimen collected from the Estancia 25 de Mayo Formation, formerly known as the Centinela Formation, in the Calafate region of southern Patagonia. Few fossil isopods are known from South America, and none were previously known from Argentina. The new occurrence reported herein further supports the environmental preferences of the genus throughout its geological past for deep-marine settings.Ĭirolana centinelensis, a new species of fossil cirolanid isopod from the early Miocene of Argentina is described, and the fossil record of South American isopods is briefly reviewed.
At the time of deposition of these marls, the area represented a part of the Norbetic Strait, a corridor connecting the North-East Atlantic with the Mediterranean. The new species is so far known only from the type locality in close vicinity of Arroyo Trujillo, in the municipality of Cantillana (Seville, Spain), where the marls of the Écija Formation are exposed. differs from its congeners by both uropod rami having the obtuse distolateral corner produced as a distinct tip and a wider gap between the second and third side distal spines than between others. Based on a single posterior moult from the upper Miocene (Tortonian) of southwestern Spain, a new species is described. Herein, a somewhat older occurrence of the genus is reported, from the North-East Atlantic. In not so distant geological past, however, the genus was present also in the Mediterranean, as documented by numerous fossils from the Plio–Pleistocene of Italy. Today representatives of the giant cirolanid isopods of the genus Bathynomus inhabit tropical to warm-temperate waters of the West Atlantic and the Indo-West Pacific.
0 kommentar(er)
