Search results for "Protoconch"
showing 3 items of 3 documents
Distinct protoconchs recognised in three of the larger Mediterranean Cerithium species (Caenogastropoda: Cerithiidae)
2017
The gastropod genus Cerithium includes several polymorphic species which are hardly distinguishable using a morphological approach based on teleoconch characters. Here we show that protoconch characters can be reliably used to identify the larger Mediterranean species (Cerithium alucastrum, C. repandum and C. vulgatum), and to assess their intraspecific variability. Based on a large amount of morphological data, we show that a multispiral, strongly sculptured protoconch (traditionally associated with C. vulgatum) is found in C. alucastrum. This species originated in the Pliocene. A multispiral, weakly sculptured protoconch, not observed previously, is reported for C. vulgatum. A paucispiral…
Embryonic Ammonoid Shell Features: Intraspecific Variation Revisited
2001
Two samples of ammonoids belonging to the Oppeliidae, Sublunuloceras virguloidesHecticoceras (Brightii) canaliculatum, are analyzed to estimate the intraspecific variability of embryonic shell features. The study of embryonic shell characters reveals two main shapes of protoconch, flattened and round. Prosiphons may be straight or slightly curved. New parameters for area are added to the linear parameters commonly found in the literature. Prosiphon length and caecum area vary greatly whereas protoconch and ammonitella diameter vary only slightly, and the ammonitella angle is almost constant. The protoconch-to-ammonitella size ratio behaves differently in each species, suggesting different p…
KYLLINIA PARENTALIS (NEOGASTROPODA: TURRIDAE), NEW GENUS AND SPECIES FROM THE PLIO–PLEISTOCENE OF THE CENTRAL MEDITERRANEAN AREA
2007
Abstract A new genus and species of turrid neogastropod, Kyllinia parentalis, is described based on three shells from the Pliocene (North Italy) and the Pleistocene (northwestern Peloponnesus) of the central Mediterranean area. The new taxon is compared to the buccinid (sensu lato) genus Metula H. and A. Adams, 1853 with which it shows a few superficial similarities mainly limited to the latticed sculptural pattern of the teleoconch. Kyllinia parentalis is placed in the turrid subfamily Mangeliinae on the basis of teleoconch characters (double sinuosity of the outer lip and the short, forward curved anterior canal) and protoconch (a characteristic pattern formed by narrow axial riblets givi…