Convex Whorls Research Articles

Similar shells in different seas: the case of Atlantic Brachystomia carrozzai (van Aartsen, 1987) and two allied Mediterranean species (Gastropoda: Pyramidellidae)

The comparison of shells of Brachystomia carrozzai (van Aartsen, 1987) of Atlantic and Mediterranean origin allowed us to detect slight but constant morphological differences. In particular, Mediterranean specimens, here attributed to Brachystomia pizzinii n. sp., show, with respect to B. carrozzai, a more protruding and widely umbilicated protoconch, and a teleoconch with more convex whorls and clear suture. A further species with distribution limited to the waters of southern Spain, in the literature attributed to B. carrozzai as well, is described here as Brachystomia hispanica n. sp. The latter is distinguished from both B. carrozzai and B. pizzinii due to its small size and broader profile. Further, Brachystomia sorianoi (Peñas & Rolán, 2006) is reported for the first time from the Bay of Algeciras.

An inventory of molluscs recorded from mid-Cretaceous Burmese amber, with the description of a land snail, Euthema annae sp. nov. (Caenogastropoda, Cyclophoroidea, Diplommatinidae)

A new species of Euthema of mid-Cretaceous age (Cenomanian, ca. 99–98 Ma), E. annae sp. nov., is described on the basis of two shells in Burmese amber (northern Myanmar). It differs by the presence of a parietal inclusion in the aperture and by the weakly convex whorls with dense, diagonally aligned ribs on the last whorl. The genus Euthema is redescribed, and a new synonym recognised, Paleodiplommatina. A list of all currently described molluscan species from Burmese amber is provided. Lagocheilus electrospira is reassigned to the genus Eotrichophorus. The taxonomic diversity and abundance of molluscs in Burmese amber are discussed on the basis of 198 observed snail inclusions from amber trading exchange and published data. Apparently, molluscs are much more common in Burmese amber than in any other deposit of amber, with a notable predominance of Cyclophoroidea. There are no specimens that could indicate the presence of Stylommatophora, Ellobioidea or other “pulmonates”.

Bouchetispira ponderi n. sp. (Conoidea: Bouchetispiridae), a new deep-sea gastropod from temperate Australia

ABSTRACTThis study presents the first record of the previously monotypic family Bouchetispiridae (Neogastropoda: Conoidea) outside of New Caledonia and provides the taxonomic description of Bouchetispira ponderi n. sp. from deep waters off the coast of New South Wales, Australia. Molecular analysis based on cytochrome c oxidase subunit I (COI), 16S ribosomal RNA (16S rRNA) and 12S ribosomal RNA (12S rRNA) mitochondrial markers confirms its placement within the family, which is corroborated based on similarities of the shell and hypodermic radula to its sister taxon Bouchetispira vitrea. B. ponderi differs from the latter in having shouldered, distinctly less convex whorls and a thicker, more opaque shell, as well as in details of the radula. Furthermore, the molecular results presented herein support its recognition as a new species. B. ponderi bears notable similarities in several shell characters to Belomitra pacifica (Belomitridae), providing another example of convergence with regard to shell morphology in the Neogastropoda.

Eulimacrostoma gen. nov., a new genus of Eulimidae (Gastropoda, Caenogastropoda) with description of a new species and reevaluation of other western Atlantic species

A new genus and a new species of Eulimidae are described based on the shell morphology and on the host-parasite relationship of the type species. Eulimacrostomamicrosculpturata Souza & Pimenta gen. nov. and sp. nov. parasitizes a starfish of the genus Luidia and has an elongated, conical, straight, or slightly curved shell, a protoconch with a brownish spiral band and convex whorls, a peculiar large and broad aperture with a strongly protruding outer lip, and microsculpture of axial lines on the teleoconch. Four other species are included in the genus, all from the western Atlantic: Eulimacrostomachascanon (Watson, 1883), comb. nov., Eulimacrostomafusus (Dall, 1889), comb. nov., Eulimacrostomalutescens (Simone, 2002), comb. nov., and Eulimacrostomapatula (Dall & Simpson, 1901), comb. nov. Newly available material of Eulimacrostomapatula expands the known geographic distribution of this species in the Caribbean to the north coast of Brazil. Eulimacrostomachascanon and Eulimacrostomafusus and Eulimacrostomalutescens are known only by the type series which was re-examined. A redescription is provided for Eulimacrostomachascanon and Eulimacrostomafusus. Species within Eulimacrostoma differ mainly by teleoconch sculpture, the presence or absence of an umbilical fissure, and shell dimensions. Lectotypes are designated for Eulimacrostomachascanon, Eulimacrostomafusus, and Eulimacrostomapatula.

A New Genus and Two New Species of Fossil Continental Gastropods from the Early Pliocene of Argentina (Mollusca)

A new genus and two new fossil species of continental gastropods from the upper part of the Irene Formation—which is probably Huayquerian–Montehermosian (early Pliocene) and is exposed in the Quequén Salado River (Buenos Aires Province, Argentina)—are described: the new genus and species of freshwater gastropod Argentisioliella pardignasi (Cochliopidae) and a new species of landsnail of the family Bulimulidae (Bocourtia (Kuschelenia?) bonariensis). Argentisioliella pardignasi is morphologically related to those described for the Pebas Formation of Pliocene age. The specimens have bulloid morphology, long and narrow aperture, with a channeled peristome and two folds in the columellar wall. This is the first description of similar snails of the Pebas and Irene formations. Bocourtia (Kuschelenia?) bonariensis is the most ancient record for the genus, being recorded far away from the area of its current distribution (northwest Argentina). The specimen is an internal cast, with more than three convex whorls and a large aperture. Its distribution would coincide with the final phase of the Mio–Pliocene climatic change, when numerous terrestrial gastropods of Patagonian and Pampean provenance disappeared. A well-conserved specimen of the terrestrial snail Austroborus (Strophocheilidae Pilsbry), showing an almost complete shell, with more than 4.5 convex whorls, last whorl and large aperture, was also recorded. In the study area, this genus was present during the Pleistocene and Holocene, living in restricted areas of Argentina and Uruguay, with a disjunctive and relictual distribution.

New species of Cyclodontina from Bahia, Brazil (Gastropoda, Pulmonata, Odontostomidae)

A new species of pulmonate snail was recently collected in a small forest fragment in the city of Bom Jesus da Lapa, Bahia state, Brazil. Bahia is known for a high diversity of land snails and Bom Jesus da Lapa is an interesting locality, since it is close to the interface between two major Brazilian biomes: Cerrado and Caatinga. The new species is described as Cyclodontina tapuia sp. nov. and can be easily identified by its brown shell, conical spire, convex whorls, a sculpture comprised of strong ribs, and an aperture with four barriers: a median parietal tooth, a median palatal tooth, a median basal tooth and a strong columellar lamella. This discovery is also a reminder of how little the Brazilian continental molluscan fauna is known and of the urgency in studying and preserving the rich (though usually overlooked) fauna of the Caatinga.

Lectotype designation for Murex nebula Montagu 1803 (Mangeliidae) and its implications for Bela Leach in Gray 1847.

Bela Leach in Gray is a misapplied and broadly defined genus within the family Mangeliidae Fischer, 1883. Examination of material from the Montagu collection at the Royal Albert Memorial Museum & Art Gallery (RAMM) in Exeter (UK) led to the discovery of six specimens of Murex nebula Montagu 1803 (the type species of Bela). This material is considered to belong to the original lot used by Montagu to define his species. We selected the best-preserved specimen as a lectotype. The lectotype and paralectotypes deposited at the RAMM are fully described and illustrated. Furthermore, diagnostic characters for recognizing B. nebula specimens are presented: protoconch shows weak ornamentation; teleoconch is fusiform with slightly convex whorls characterized by broad, suture-to-suture ribs and dense but weak spiral elements; outer lip is thin; anal sinus is shallow, placed on the shoulder ramp. These key features are of basic importance for: i) restricting the usage of the genus Bela and promoting its stability and consistent usage in literature and ii) separating two allied (and sometimes interchanged) genera: Bela and Mangelia Risso 1826.

Comparative Morphology and Redescription of Three Species ofCalliostoma(Gastropoda, Trochoidea) from Brazilian Coast

The morphology of Calliostoma adspersum, C. depictum and C. hassler, from the Brazilian coast, were studied in detail. Their anatomy has particularities that may be unique to the genus, such as: presence of an ampulla in the female; reduction or loss of the cephalic lappets; presence of a pseudoproboscis; occurrence of the intestinal loop outside the head-foot haemocoel. At species level, we conclude that C. vinosum is a synonym of C. hassler, because specimens identifiable as both species occur within a single ontogenetic series. Calliostoma hassler can be distinguished by: lack of the left dorsal esophageal fold, absence of a gastric spiral caecum and presence of an intestine with two wide loops. Based on anatomical evidence, we concluded that C. depictum is not a synonym of C. adspersum, differing by strongly convex whorls and a distinct suture; a marked groove near the columella; an odontophore partially covered by the mid-esophagus; absence of the pair of odontophore muscles m8a; a ventral esophageal fold of the same size as the dorsal folds; and a reduced spiral caecum with 0.5 whorl.

Description of a new species of Calliostoma (Gastropoda, Calliostomatidae) from Southeastern Brazil

Calliostoma tupinamba isa new species from Southeastern Brazil, ranging from southern Rio de Janeiro to northern São Paulo, and found only on coastal islands, on rocks and sessile invertebrates at 3 to 5 meters of depth. Shell and soft part morphology is described here in detail. Calliostoma tupinamba is mainly characterized by a depressed trochoid shell; eight slightly convex whorls; a sharply suprasutural carina starting on the third whorl and forming a peripheral rounded keel; and a whitish, funnel-shaped and deep umbilicus, measuring about 5%–10% of maximum shell width. Calliostoma tupinamba resembles Calliostoma bullisi Clench & Turner, 1960 in shape, but differs from it in being taller and wider, having a smaller umbilicus and lacking a strong and large innermost spiral cord at its base. Finally, an identification key of Brazilian Calliostoma species is presented.

Australocosmica,A New Genus of Land Snails from the Kimberley, Western Australia (Eupulmonata, Camaenidae)

The Western Australian Kimberley region harbours a diverse fauna of camaenid land snails characterised by marked patterns of narrow range endemism. A recent survey of previously poorly known areas along the Kimberley coast has resulted in the discovery of a number of further, yet undeschbed camaenid taxa. One of these, the genus Australocosmica, is newly described herein based on comparative studies of genital anatomy, shell and radular morphology, and analyses of partial sequences of the mitochondrial marker 16S rRNA. Australocosmica is characterised by a broadly conical to semi-globose shell with moderately elevated spire, well-rounded, convex whorls that are separated by a deeply incised suture, and a sculpture of dense, regularly spaced axial ribs. The most distinguishing feature of the inner penial anatomy is the presence of a furrowed, collar-like vergic papillum forming the entrance of the vas deferens into the lumen of the penial chamber. Three new species, Australocosmia augustae, A. sanctumpatriciusae, and A. vulcanice, are described based mainly on differences in penial anatomy. All species are well differentiated by uncorrected pair-wise p-distances of 15% to 20% in the 16S rRNA gene. Similar to most camaenids in the Kimberley region, species of Australocosmica are narrow-range endemics being restricted to single islands, sometimes including the immediately adjacent mainland coast.

Araucocharopa gallardoi gen. et sp. n. de Charopidae (Mollusca: Gastropoda: Stylommatophora) del sur de Chile

Araucocharopa gallardoi gen. et sp. n. of Charopidae (Gastropoda: Stylommatophora: Punctoidea) from Southern Chile. Araucocharopa gallardoi gen. et sp. n. from Southern Chile is described. It is characterized by a small trochoid shell (mean diameter: 1.8 mm), 4 ½ - 5 convex whorls, body whorl subcuadrangular; elevated spire (mean height / diameter: 0.74); adult sculpture of high, prominent and vertical 120 axial ribs; periostracal lamelae growing on the axial ribs; protoconch of 1 ¾ whorls with microsculture consisting of 12 spiral costulae with barely visible irregular rings; semilunate aperture descending basally; umbilicus very narrow. The ringed spiral costulae of protoconch is a distinctive feature into the family Charopidae. As part of the discussion, the protoconchs of type species of Stephanoda and Austrodiscus are described for the first time, the embrionic sculpture of S. dissimilis shows irregular axial and spiral fine ribs, and delicate incisurae; in A. twomeyi the protoconch begins smooth, showing axial ribs crossed by fine spirals costulae, not well separated from teleoconch.

Five new species of Turbonilla Risso, 1826 (Gastropoda, Heterobranchia, Pyramidellidae) found off the northeast coast of Brazil (02º-13º S)

Five new species of Turbonilla are described from the Brazilian northern continental shelf. Turbonilla virgulinoi n. sp. from off Pernambuco State (690 m depth) is diagnosed by its semi-pyriform profile and sinuous axial ribs. Turbonilla megascymna n. sp. from off Paraíba State (750 m depth) is characterized by its fragile shell and relatively large planispiral protoconch. Turbonilla kamayura n. sp. from off Paraíba State (750 m depth) is diagnosed by its slightly conical shell with convex whorls without spiral sculpture and the helicoidal protoconch. Turbonilla mermeroglaphyra n. sp. from off Alagoas State (255 m depth) has a slightly telescopic shell and is almost straight in profile; axial ribs become obsolete toward the last whorls. Turbonilla aquilonaria n. sp. from Pernambuco State (intertidal) is diagnosed by its tall shell without spiral sculpture and distinctly conical and almost flat-sided teleoconch whorls.

Three new species of Barleeidae (Mollusca, Gastropoda, Rissooidea) from Brazil

Three new species of the Barleedidae are described from Brazilian waters. Caelatura tigrina n.sp. from Davis Seamount (20°39’ S / 034°43’ W) is diagnosed by 5 narrow well-spaced spiral cordlets in each whorl and its golden-brown color with white axial flames. Caelatura especulabunda n.sp from Dogaressa Seamount (20°51’ S / 033°45’ W) is diagnosed by its shell oval-pupoid with slightly convex whorls and 9-10 close, thick, spiral cordlets. Protobarleeia pyrrocincta n.sp. from Abrolhos Bank (about 19° S, 38° W), the first report of the genus from South Western Atlantic, is diagnosed by its reddish belts.

A new bathyal Fasciolaria (Mollusca: Caenogastropoda) from the southwestern Caribbean

A new bathyal species of Fasciolaria is described for the southwestern Caribbean based on conchological characters. Fasciolaria tephrina sp. nov. is distinguishable from its west Atlantic congeners by its ashen white color, highly convex whorls, long thin siphonal canal, and large deviated protoconch.

Physa cubensis Pfeiffer, 1839 (Pulmonata: Physidae)

A description of Physa cubensis Pfeiffer, 1839, based on 15 speciments collected in Havana, Cuba, is presented. The shell, measuring 9.0 x 4,8mm to 12.3 x 6.4mm, is ovate-oblong, thin, diaphanous, horncolored, shining. Spire elevated, broadly conical; protoconch distinct, roundish, reddish-brown. About five moderately shouldered, roundly convex whorls, penultimate whorl expanded; spiral striation subobsolete; growth line faint on the intermediate whorls, clearly visible on the body whorl, crowded here and there. Suture well impressed. Aperture elongated 2.05 - 2.67 (mean 2.27) times as long as the remaining length of the shell, narrow obovulate-lunate; upper half acute-angled, lower half oval, narrowly rounded at the base; outer lip sharp, inner lip completely closing the umbilical region; a thick callus on the parietal wall; columellar plait well marked. Ratios: shell width/shell length - 0.52-0.61 (mean 0.55); spire length/shell length = 0.27 - 0.33 (mean 0.31); aperture length/shell length = 0.67 - 0.73 (mean 0.69). Oral lappets laterally mucronate; foot spatulate with acuminate tail. Mantle relection with 6 - 8 short triangular dentations in the right lobe (columellar side) and 4 - 6 in the left lobe (near the pneumostome). Renal tube tightly folded into a zigzag course. Ovotestis, ovispermiduct, seminal vesicle, oviduct, nidamental gland, uterus and vagina as in Physa marmorata (see Paraense, 1986, Mem. Inst. Oswaldo Cruz, 81: 459-469). Spermathecal body egg-shaped or pear-shaped; spermathecal ducta uniformly narrow with expanded base, a little longer than the body. Spermiduct, prostate and vas deferens as in P. marmorata (Paraense, loc. cit.). Penis wide proximally, narrowing gradually apicad; penial canal with subterminal outlet. Penial sheath following the width of the penis and ending up by a bulbous expansion somewhat narrower than the proximal portion. Penaial sheath/prepuce ration = 1,25 - 1,83 (mean 1.49). Prepuce much wider than the bulb of the penial shealth, moderately shouldered owing to the intromission of the bulb, and with a large gland in one side of its proximal half occupating about a third of its length. Extrinsic muscles of the penial complex as in P. marmorata. Jaw a simple obtusely V-shaped plate. Radula to be described separetely.

Physa Marmorata Guilding, 1828 (Pulmonata: Physidae)

A description of Physa marmorata Guilding, 1828, based on material collected at its type-locality, the Caribbean island of Saint Vincent, is presented. The shell is thin, horn-colored, surface very glossy, diaphanous. Spire acute, elevated; protoconch distinct, rounded-conical, reddish-brown; five not shouldered, broadly convex whorls with subobsolete spiral lines and thin growth lines. Aperture elongated, 1.4-2.0 times as long as the remaining shell length, narrow obovate-lunate; upper half acute-angled,lower half oval,narrowly rounded at the base, outer lip sharp, inner lip completely closing the umbilical region; a very distinct callus on the parietal wall; columellar lip with a low ridge gradually merging into the callus. ratios: shell width/shell length = 0.44 - 0.52 (mean 0.47); spire length /shell lenght = 0.33-0.41 (mean 0.39); aperture length/shell lenght = 0.59-0.67 (mean 0.62). Oral lappets laterally mucronate, foot spatulate with deeply pigmented acuminate tail. Mantle reflection with 6-10 short triangular dentations covering nearly half the right surface of the body whorl, and 4-6 covering a part of the ventral wall. Body surface with tiny dots of greenish-yellow pigment besides melanin. Renal tube tightly folded in toa zigzag course. Ovotestis diverticula acinous, laterally pressed against each other around a collecting canal. Ovispermiduct with well-developed seminal vesicle. oviduct highly convoluted, merging into a less convoluted nidamental gland which narrows to a funnel-shaped uterus and a short vagina. Spermathecal body oblong, more or less constricted in the middle and somewhat curved; spermathecal duct uniformly narrow, a little longer than be body. About 20 prostatic diverticula, simple, bifurcate or divided into a few short branches, distalmost ones assembled into a cluster. Penis long, nearly uniformly narrow; penial canal with lateral opening about the junction of its middle and lower thirds. Penial sheath with a bulbous terminal expasion the tip of which isinserted into the caudal end of the prepuce. Prepuce shouldered, much wider than the narrow portion of the penial sheath. Penial sheath/prepuce ratio about 2.08 (1.45-2.75). The main extrinsic muscles of the penial complex are a retractor, with a branch attached to the bulb, and another to the caudal end of the penial sheath; and a protractor, with a branch attached to the shoulder of the prepuce and adjoining area of the penial sheath, and another to the caudal end of the penial sheath. Egg capsule C-shaped, with 10-30 elliptical eggs (snails 10mm long) measuring about 1.10 mm (0.90-1.32) through the long axis and surrounded by an inner and an outer lamellate membranes. Jaw a simple obtusely V-shaped plate. radula will be described separately.

Observations on some of the Loxonematidæ, with Descriptions of Two New Species

T he genus Loxonema was founded by Phillips in 1841, and was thus described by him:— ‘Spiral, turriculated; whorls convex, their upper edges adpressed against the next above; without spiral band; mouth oblong, attenuated above, effused below, with a sigmoidal edge to the right lip; no umbilicus (?); surface covered by longitudinal threads or ridges, generally arched.’ He further states that these observations are merely provisional, until the form of the aperture is more perfectly known. In noting the number of species, he writes that most of them are probably ‘varieties of three or four types having L. sinuosa for one extremity and L. Hennahii for the other; a second related to L. tumida and L. lincta ; a third to L. rugifera .‘ [ Loc. cit. ] Later researches show that this description is correct for the group of shells having Loxonema sinuosum for the type, and the generic name must be restricted to them. The essential characteristics are the possession of whorls adpressed at the suture and the presence of strongly-sigmoidal lines of growth. Shells having more convex whorls, or less sigmoidal lines of growth, must be placed elsewhere. Prof. Koken and other palæontologists have created several new genera for some of these latter. The type, Loxonema sinuosum , is the first species described by Phillips: it is a Devonian form from South Petherwyn, which he identifies with Terebra (?) sinuosa , Sow. from the Aymestry Limestone. They are probably distinct species, although Mr. Whidborne thinks them correctly identified. The striæ on the Devonian form

II—On the Gault Aporrhaidæ

Shell elongated, spire composed of many convex whorls, which are very finely striated, 2 or 3 of the striæ being very distinct and wide apart in front of the sutures. The last 2 whorls have 10 or 11 and the other whorls have 14 or 16 well-marked ribs, with occasional varices. On the last whorl there is a slight angularity in place of keel. The wing exactly resembles that of A. Parkinsoni, and in this may be distinguished from that of A. Mantelli. The anterior canal is moderately long.