AUTOCHTHONOUS BIOFACIES IN THE PLIOCENE LORETO BASIN, BAJA CALIFORNIA SUR, MEXICO

The present paper examines the molluscan and/or echinoid assemblages recovered from two lithostratigraphic units (Piedras Rodadas Sandstone and Arroyo de Arce Norte Sandstone) outcropping in the Pliocene Loreto Basin, Baja California Sur, Mexico. Ten biofacies have been identified, i.e. Trachycardium procerum-Trachycardium senticosum Biofacies, Chione compta-Transennella modesta Biofacies, Laevicardium elenense-Chione kelletii Biofacies, Xenophora sp. 1-Strombus subgracilior Biofacies, Crassostrea californica osunai Biofacies, Myrakeena angelica Biofacies, Vermetid-Nodipecten Biofacies, Argopecten abietis abietis Biofacies, Aequipecten dallasi Biofacies and Encope Biofacies. The first four biofacies have been defined on the basis of statistical analyses (cluster analysis, MDS). The other six, which are monospecific or definitely low-diversity, were already identified during field work. The deduced paleoecological bearing of biofacies, largely relying upon the comparison to their closest modern counterparts, provides the basis for the paleoenvironmental reconstruction. The latter also considers sedimentological evidence and is framed within the tectonic and sedimentary context recently proposed by American workers. Biofacies point toward environments differing in terms of substrate texture, presence/absence of vegetal cover, energy level, variously distributed within the low tide mark-40 m bathymetric range.&nbsp

EOCENE, OLIGOCENE AND MIOCENE NATICID GASTROPODS OF NORTHERN ITALY

The present paper covers 77 species and six subspecies of naticid gastropods occurring in the Eocene, Oligocene and Miocene units of Northern Italy; all are described and commented on in the systematic account. Forty-two taxa are identified as formerly described ones; of these, 16 are associated with a generic name different from the previous one, and four are ranked at a different taxonomic level. Twenty-four taxa are proposed as new and the rest likely represent undescribed species, but more, better preserved material is required in order to establish their identity and to name them. Of the 83 taxa considered, 17 are assigned to the genus Cochlis Röding, 1798, one belongs in Cryptonatica Dall, 1892, another belongs in Tanea Marwick, 1931, 11 are members of the genus Tectonatica Sacco, 1890, three are included in Ampullonatica Sacco, 1890, one belongs in Eunaticina Fischer, 1885, 20 are assigned to Euspira Agassiz in J. Sowerby, 1837, three belong in Neverita Risso, 1826, five belong in Payraudeautia Bucquoy, Dautzenberg & Dollfus,1883, two agree with the characters of Pliconacca Cossmann & Martin in Martin, 1914, four are members of Polinices Montfort, 1810, two belong in Sigatica Meyer & Aldrich, 1886, four belong in Sigaretotrerma Sacco, 1890, and nine have the characters of the genus Sinum Röding, 1798. All genera are discussed in terms of type species designation, distinctive characters and subfamilial affiliation (when different from the current one).  The character analysis has shown that the measurable elements of the protoconch along with its microsculpture (if any) are diagnostic in many species of all subfamilies. The features of the outer surface of the calcareous operculum proved to be diagnostic in the Pliocene and Recent naticine species. In the present case, the operculum of only four Cochlis species is known, readily differentiating them from one another. The umbilical characters, i.e. umbilicus width and presence/absence and strength of inner spiral structures, proved to be of variable utility in identifying species. The inner umbilical characters are never species-diagnostic in the case of the naticine taxa, particularly those of Cochlis. The inner structures, primarily presence/absence, number and strength of cordlets or threads on the umbilical bottom, are more effective in distinguishing poliniceine taxa. The umbilical callus can be used diagnostically for a limited number of naticine and poliniceine taxa. The exterior sculpture of the teleoconch (absent in the naticine and in most poliniceine taxa) is well developed in all the sinine species. In the case of Sigaretotrema and Sinum, the sculptural characters proved to be relevant in species recognition. The color pattern is diagnostic in most of the taxa in which this character is preserved. The shell morphology and the apertural characters are relevant only in a few cases. In the absence of diagnostic elements, a combination of all characters can help in recognizing species

PECTINIDS AND OYSTERS FROM THE PLIOCENE LORETO BASIN (BAJA CALIFORNIA SUR, MEXICO)

Fourteen pectinid and oyster species from the Pliocene Loreto Basin (Baja California Sur, Mexico) are recorded and discussed with regard to their relationships with closely related taxa. The whole assemblage points toward a Pliocene age. Aequipecten dallasi and Argopecten abietis abietis resulted to be the most useful biostratigraphic taxa, being restricted to Pliocene. The bulk of the considered species were confined within southern regions during the Pliocene. Crassostrea californica osunai is likely to have been endemic of Baja California Sur. Pectinids and oysters appear to have inhabited fine to coarse shallow infralittoral bottoms wave- or current-nfluenced. The environmental energy was the main factor controlling presence/absence of species. Finally, a unusual vermetid-Nodipecten association is described and interpreted in terms of paleoenvironmental meaning

NOTES ON SOME PLIOCENE GASTROPODS FROM RIO TORSERO, WESTERN LIGURIA. ITALY

The present paper is the second of a series dedicated to Pliocene molluscs of Liguria. lt deals with 13 gastropods species belonging to the superfamilies Rissoacea, Rissoinacea, Cerithiopsacea and Triphoracea. The generic assignment of each taxon is reviewed on the basis of the protoconch characters, and the description is provided for less known species. The genera Cerithiopsidella and Retilaskeya are quoted for the first time in Mediterranean area as well as Rissoina (Rissoina) varicosa Boettger and Metaxia abrupta (Watson). The new species Alvania (Alvania) obliquistoma is proposed

REMARKS ON THE AGE OF THE LIMESTONES OF SOUTHEASTERN JAVA (INDONESIA)

The present paper deals with the age assignment of the limestones (Wonosari Formation) cropping out in the East Southern Mountains of South East Java (Indonesia), based on the foraminiferal assemblages observed in several limestone samples from that area. The assemblages are typical of Lower Tf stage; ages range from planktonic foraminiferal Zone N8 toZone N9 or are slightly younger, corresponding to Langhian and earliest Serravallian in terms of Mediterranean stages. The limestones with Flosculinella bontangensis of the East Southern Mountains of Java, have the same age of those of the Australian margin. They correlate with Zone N9 or with a stratigraphic interval ranging from Zone N9 to basal N10

THE REMBANGIAN (MIDDLE MIOCENE) MOLLUSK-FAUNA OF JAVA, INDONESIA. I. ARCHAEOGASTROPODA

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A REVISION OF THE PLIOCENE NATICIDS OF NORTHERN AND CENTRAL ITALY. II. THE SUBFAMILY NATICINAE: ADDITIONS TO COCHLIS, TANEA AND TECTONATICA

The present paper is the second in a series devoted to the revision of the Pliocene naticids of Northern and Central Italy. It concludes the section covering the calcareous operculum-bearing Naticinae and expands to 18 the total number of species and subspecies of this subfamily recovered so far from the Pliocene deposits of Italy. Of the six taxa considered in this study, two (epigloafuniculata and fredianii) fully match the characters of the genus Cochlis Röding, 1798, one (koeneni) is assigned to the genus Tanea Marwick, 1931, the rest (astensis, prietoi and tectula) belong to the genus Tectonatica Sacco, 1890. All the six taxa considered in this paper are described and commented in the systematic account. One, Cochlis fredianii, is proposed as new. In the chapter treating the generic assignment of the studied taxa, the range of Tanea, hitherto used to allocate several Indo-Pacific species, is extended to the Mediterranean Basin as well, and the relations between Tectonatica and Cryptonatica Dall, 1892 are discussed. This study further demonstrates that the morphological characters of the teleoconch are of low significance in species recognition. In fact, should the characters be ranked, the operculum comes first and is the primary element, sufficient to distinguish each species. The protoconch and the color pattern are the second and third relevant attributes that can be used diagnostically for several taxa, but not always. The other shell features appear to be useful tools in separating species only occasionally. Some species lack distinctive shell characters and do require operculate specimens in order to be confidently

A REVISION OF THE PLIOCENE NATICIDS OF NORTHERN AND CENTRAL ITALY.III. THE SUBFAMILIES POLINICEINAE AND SININAE

The present paper is the third in the series and concludes the revision of the Pliocene naticids of northern and central Italy. It expands to 31 the total number of species and subspecies of this family recovered so far from the Pliocene deposits of the investigated area. Of the thirteen taxa covered in this study, eight (bononiensis, exturbinoides, grossularia, guillemini, helicina helicina, magenesi, notabilis and pulchella) belong to the genus Euspira Agassiz in J. Sowerby, 1837, one (olla) belongs to the genus Neverita Risso, 1826, two others (fasciolata and intricata) are members of Payraudeautia Bucquoy, Dautzenberg & Dollfus, 1883, and the last two (perregulare and striatum) belong to the genus Sinum Röding, 1798. All thirteen taxa considered in this paper are described and commented on in the systematic account. Since species herein recorded under Euspira were often assigned to Polinices Montfort, 1810 by earlier workers, both genera are discussed and their characters are defined on the basis of their respective type species. A significant output is that the tropical genus Polinices, well represented in Late Oligocene and Miocene naticid assemblages of Europe, disappeared from that area and there are no reliable records of it subsequent to the Tortonian. Also the relations between Polinices and Neverita are discussed and their respective distinguishing characters are pointed out. This study demonstrates that the taxonomic relevance of a particular character may change greatly depending on the subfamily considered, and cannot be extended to Naticidae as a whole. Naticine species are confidently identifiable primarily by characters of their opercula. These latter can be combined with protoconch characters and color patterns, umbilical callus and umbilical characters in descending order of importance. Poliniceine and sinine species are readily and univocally distinguished by a combination of protoconch and umbilical characters, the larval shell being the most important element. In the case of Neverita, Payraudeautia and Sinum species, the teleoconch shape, the aperture and the umbilical callus also may have diagnostic value. The teleoconch shape appears to have been overrated by most workers

A REVISION OF THE PLIOCENE NATICIDS OF NORTHERN AND CENTRAL ITALY. I. THE SUBFAMILY NATICINAE EXCEPT TECTONATICA

The present paper is the first in a series devoted to the revision of the Pliocene naticids of Northern and Central Italy. It recovers some previously disregarded but valid species and expands the number of naticine taxa (Tectonatica excluded) from four to twelve. Of these, one belongs to the genus Natica Scopoli, 1777, the others are assigned to the genus Cochlis Röding, 1798 which is reused herein for the first time after more than one century. The vast material examined (personal and museum collections) has allowed to analyze all shell and opercular characters, in terms of range of variation and significance in species recognition. The study demonstrates that the morphological characters of the teleoconch, such as the height of the spire, the suture, the umbilical features and the sculpture (subsutural axial wrinkles), are diagnostic only in some instances as it happens with the color. The operculum stands as the most significant diagnostic element in that is species-specific and, thence, sufficient to recognize each taxon. The protoconch is relevant as well to distinguish several, but not all species. The characters which are necessary and/or sufficient for the identification of the species considered in this study are summarized in the conclusive remarks. All the twelve taxa considered in this study are described and commented in the systematic account. One species, Cochlis sulcogradata, and one subspecies, Cochlis raropunctata obliquicallosa, are proposed as new.

EUSPIRA MAGENESI, A NEW SPECIES OF THE NATICIDAE (GASTROPODA) FROM THE PLIOCENE OF ITALY

The new naticid species Euspira magenesi is described and figured. The type-material was recovered from Pliocene deposits exposed along the stream Rio Rosello (Emilia region, Piacenza province) and near Villalvernia (Piedmont, Alessandria province).The small-sized Euspira magenesi is featured by channeled suture, open, rather wide umbilicus and abapically produced aperture. It is an uncommon infralittoral element likely related to ecotones between paleobiocoenoses similar to the modern Mediterranean SFBC and DC.