Euthecosomata (Mollusca, Gastropoda, Thecosomata). Taxonomic review

The Euthecosomata Meisenheimer, 1905, holoplanktonic Mollusca with coiled or straight shell were respectively classified in Limacinoidea Gray, 1847 and Cavolinioidea Gray, 1850. In a biometrical analysis (Rampal 1973) a first change had occurd in this last superfamily: the conica shell genera Creseis Rang, 1828, Boasia Dall, 1889, Styliola Gray, 1850 and Hyalocylis Fol, 1875 were gathered into the Creseidae Rampal, 1973. Therefore it was necessary to carry on this study using molecular data. Our recent cladistic and molecular analyses as well as palaeontologic data led to a systematic and phylogenetic revision of the Euthecosomata: the Limacinoidea and of the Creseidae are not monophyletic, the other straight shells Euthecosomata are monophyletic (Corse et al. 2013). The Limacinoidea are invalidated; they are split into three families: Limacinidae Gray, 1847, Heliconoididae n. fam. and Thieleidae n. fam. The Creseidae Rampal, 1973 are validated but at least there are two genera Creseis Rang, 1828 and Boasia Dall, 1889; Styliola and Hyalocylis are considered incertae sedis. In the Cavoliniidae Gray, 1850 there are four subfamily: Cuvierininae Gray, 1850 , Cliinae Jeffreys, 1869 , Diacriinae n. subfam., Cavoliniinae Gray, 1850. The Creseidae Rampal, 1973 and the Cavoliniidae Gray, 1850 belong to the Cavolinioidea Gray, 1850. The species rank of most taxa is confirmed. New genera are proposed or reinstated: Telodiacria n. gen., Hyalaea de Blainville, 1821, Boasia Dall, 1889. The fossil Vaginella Daudin, 1800 is included within the Cuvierininae Gray, 1847. The spiral fossil Altaspiratella Korobkov, 1966 is no longer considered part of the Limacinidae Gray, 1847. Two phylogenetic hypotheses are analysed. According to molecular analyses in COI there is the double emergency of straight shell from two coiled shell lineages; in 28S there is monophyly; this last hypothesis we have kapt is the most parsimonious but requires some reserve and new investigations (Corse et al. 2013)

Clio oblonga n. sp. (Mollusque, Gastéropode, Euthécosome, Cavoliniidae, Clionae) fossile de thanatocœnoses quaternaires de la Méditerranée

Clio oblonga n.sp. (Mollusca, Gastropoda, Euthecosomata, Cavoliniidae, Clionae) fossil from Mediterranean Quaternary thanatocœnoses. Clio oblonga n.sp., has been dredged in Quaternary sediments in the Tyrrhenian Sea. The shell, oval, has a lozenge-shaped transversal section ; it has a double transversal striation. This new species is compared with other transversely striated Clio, i.e. present species and fossile ones from the Miocene and Pliocene. This fossile is probably a warm species with a restricted geographic and duration range ; it disappeared just before the actual sedimentary period. After the post-glacial period, other warm Thecosomata also disappeared from the Mediterranean, but they are actually found in the tropical Atlantic from which they had colonized the Mediterranean during an interglacial warm period.Clio oblonga n.sp. a été draguée dans les sédiments quaternaires de la mer Tyrrhénienne. La téloconque, ovale, a une section transversale losangique ; elle est doublement striée transversalement. Cette nouvelle espèce a été comparée à d'autres Clio à striation transversale, espèces actuelles et fossiles du Miocène et du Pliocène. Ce fossile, probablement thermophile, est limité spatio-temporellement ; apparu en Méditerranée vers la fin du Quaternaire, il se serait éteint sur place avant la période de sédimentation actuelle. A la fin de la période post-glaciaire, d'autres Thécosomes thermophiles ont disparu aussi de la Méditerranée mais on les trouve encore actuellement dans l'océan Atlantique tropical à partir duquel ils avaient très probablement colonisé la Méditerranée lors de passées chaudes.Rampal Jeannine. Clio oblonga n. sp. (Mollusque, Gastéropode, Euthécosome, Cavoliniidae, Clionae) fossile de thanatocœnoses quaternaires de la Méditerranée. In: Géologie Méditerranéenne. Tome 23, numéro 3-4, 1996. pp. 175-185

Biodiversité et biogéographie chez les Cavoliniidae (Mollusca, Gastropoda, Opisthobranchia, Euthecosomata). Régions faunistiques marines

Rampal, Jeannine (2002): Biodiversité et biogéographie chez les Cavoliniidae (Mollusca, Gastropoda, Opisthobranchia, Euthecosomata). Régions faunistiques marines. Zoosystema 24 (2): 209-258, DOI: http://doi.org/10.5281/zenodo.539422

Biodiversité et biogéographie chez les Cavoliniidae (Mollusca, Gastropoda, Opisthobranchia, Euthecosomata). Régions faunistiques marines

Plusieurs Cavoliniidae nouveaux pour la science sont décrits ici : Cavolinia gibboides n. sp. (groupe gibbosa), Diacria gracilis n. sp. (groupe trispinosa), Creseis conica falciformis n. ssp., Creseis virgula frontieri n. ssp., Cavolinia longicostata n. sp., Cavolinia pachysoma n. sp., Cavolinia labiata robusta n. ssp. (groupe inflexa), Clio convexa cyphosa n. ssp. (groupe pyramidata) et Diacria trispinosa heterocolorata n. ssp., les cinq derniers provenant de sédiments récents. Le rang spécifique est attribué à plusieurs sous-espèces : Cuvierina urceolaris (Mörch, 1850) (synonyme Cuvierina columnella urceolaris), Cuvierina columnella (Rang, 1827) (synonyme Cuvierina columnella columnella), Cavolinia plana (Meisenheimer, 1905) (synonyme Cavolinia gibbosa plana), Cavolinia flava (d’Orbigny, 1836) (synonyme Cavolinia gibbosa flava), Cavolinia gibbosa (d’Orbigny, 1836) (synonyme Cavolinia gibbosa gibbosa), Cavolinia labiata (d’Orbigny, 1836) (synonyme Cavolinia inflexa labiata). Cuvierina columnella forma atlantica est redécrit et nommé Cuvierina spoeli n. sp. Du point de vue structural, le mode le plus répandu est la variation clinale, mais on observe aussi des isolats géographiques, notamment en Méditerranée, en mer Rouge et dans le canal de Mozambique. Le problème des phénotypes originels est posé sur la base des caractéristiques des spécimens actuels et parfois de leurs ancêtres fossiles. La biogéographie de ces différents taxons permet, d’une part, de scinder les Cavoliniidae de l’Indo-Pacifique en deux entités, celle de l’Indo-Pacifique occidental et celle du Pacifique oriental ; d’autre part, en raison de certaines similitudes faunistiques entre l’Atlantique et le Pacifique oriental, de confirmer les relations qui existaient entre ces deux océans jusqu’au Pliocène, avant l’émersion de l’isthme de Panama. La Méditerranée et la mer Rouge sont des appendices des océans Atlantique et Indien, caractérisées par la présence d’endémiques et de relictes téthysiennes, mais aussi de phénotypes originaux ou d’espèces biologiques. Malgré leur proximité et leur relation artificielle récente, ces deux mers ont des composantes faunistiques différentes : on n’a pas encore observé de migration lessepsienne chez les Euthecosomata.Several Cavoliniidae new to science are described: Cavolinia gibboides n. sp. (gibbosa group), Diacria gracilis n. sp. (trispinosa group), Creseis conica falciformis n. ssp., Creseis virgula frontieri n. ssp., Cavolinia longicostata n. sp., Cavolinia pachysoma n. sp., Cavolinia labiata robusta n. ssp. (inflexa group), Clio convexa cyphosa n. ssp. (pyramidata group) and Diacria trispinosa heterocolorata n. ssp., the last five collected in recent sediments. Several subspecies take the species level: Cuvierina urceolaris (Mörch, 1905) (synonym Cuvierina columnella urceolaris), Cuvierina columnella (Rang, 1827) (synonym Cuvierina columnella columnella), Cavolinia plana (Meisenheimer, 1905) (synonym Cavolinia gibbosa plana), Cavolinia flava (d’Orbigny, 1836) (synonym Cavolinia gibbosa flava), Cavolinia gibbosa (d’Orbigny, 1836) (synonym Cavolinia gibbosa gibbosa), Cavolinia labiata (d’Orbigny, 1836) (synonym Cavolinia inflexa labiata). Cuvierina columnella forma atlantica is redescribed and renamed Cuvierina spoeli n. sp. At the structural level, the most widespread is the clinal variation, but geographically isolated species are also recorded for example in the Mediterranean, the Red Sea and the Mozambique Channel. The problem of the primary phenotypes is evaluated on the basis of the characters of the recent species and sometimes of their fossil ancestors. The distribution of the different taxa induces to split the Indo-Pacific Cavoliniidae in two entities: the western Indo-Pacific and the eastern Pacific ones, and to point out some faunistic similarities between the Atlantic Ocean and the eastern Pacific Ocean confirming that relations existed between those two oceans until the Pliocene, before the emergence of the Isthmus of Panama. The Mediterranean and the Red seas are appendices of the Atlantic and Indian oceans but they both represent entities characterized by endemic species and Tethysian relicts along with original forms or biological species. Despite their proximity, and the recent artificial connections, the Mediterranean and the Red seas have different faunistic caracteristics: no lessepsian migration has been recorded for Euthecosomata.</p

Thecosomata in late Quternary deposits of ODP Holes 134-830A and 134-831A

We undertook a quantitative study of Thecosomata shells (pelagic gastropods) and their remains in Quaternary foraminiferal oozes deposited on the tilted calcareous platform of the Bougainville Guyot (Hole 831 A), and in the late Quaternary volcanic siltstones, claystones and sandy interbeds on the upper forearc slope of the central New Hebrides Island Arc (Hole 830A). The distribution of the species is based on the identification of adult shells, juvenile stages, protoconchs, and characteristic shell fragments. By studying thecosomatous shells using a scanning electron microscope (SEM), we were able to specify the fine microstructure of the coiled Limacina inflata and compare it with the rod-type crossed-lamellar structure of some other Limacina species, as well as with the helical structure of the Cavoliniidae