Toxoglossan gastropods of the subfamily Crassispirinae (Turridae) lacking a radula, and a discussion of the status of the subfamily Zemaciinae

Two new species of Horaiclavus, lacking radula, venom glandand proboscis, are described. The genus is placed in the subfamilyCrassispirinae (Turridae). Both species possess a peculiar foregutstructure, the muscular rhynchodaeal outgrowth situated in therhynchocoel. The possible function of the rhynchodaeal outgrowthis discussed. Other studied species of Horaiclavus possess aradula of a typical ‘crassispirine’ type but lackthe outgrowth. The anatomy of the foregut of the new speciesis superficially similar to that of Zemacies excelsa (Turridae:Zemaciinae), which also possesses an additional structure ofthe rhynchocoel, namely the ‘pyriform gland’. Conchologically,there is no resemblance between Zemacies and Horaiclavus andit is concluded that similar foregut arrangement appeared independentlyin both lineages. A new monotypic subfamily Zemaciinae was erectedmostly on the basis of the unique foregut arrangement of Zemaciesexcelsa. We express doubts concerning the importance of thesecharacters in establishing a new taxon of subfamilial rank andtherefore the validity of the subfamily Zemaciinae. (Received 16 May 2007; accepted 1 October 2007)     

TRANSFER EXPERIMENT SUGGESTS ENVIRONMENTAL EFFECTS ON THE RADULA OF LITTORARIA FLAVA (GASTROPODA: LITTORINIDAE)

Phenotypic variation in radulae has been studied in severallittorinid species because of this organ's intrinsic relationshipwith diet and, consequently, with the environment. In this work,we compared the radulae of the Brazilian species Littorariaflava found in mangroves and on rocky shores. Individuals ofL. flava showed marked differences in the shape of the cuspsamong samples from rocky shore and mangrove. In a transfer experiment,the shape of the radula changed within 40 days. A differentresponse was observed in individuals transferred to mangrove,where two different phenotypes were found, suggesting eitherintrapopulational variation in the responses to change of environmentalconditions, or that some snails showed a slow reaction to theenvironmental changes. The alterations could be attributed toecophenotypic plasticity. Analysis of variance showed that thelength of the radula in L. flava was strongly influenced bythe substrate (F_6,22=17.13, P<0.000), but apparently notby the transfer experiment. (Received 3 May 2005; accepted 18 July 2005)     

A NEW SPECIES OF THE AEOLID GENUS FLABELLINA (NUDIBRANCHIA) FROM THE STRAIT OF GIBRALTAR

A new species of nudibranch, Flabellina insolita, is describedfrom specimens from the Strait of Gibraltar. The new speciesis assigned to the genus Flabellina on the basis of the jaws,radula and reproductive system, despite the shape of the rhinophoresand oral tentacles and the presence of small papillae flankingthe pericardium and small laminar enlargements on the dorsalsurface of the body. These features separate this species fromother aeolids. (Received 14 June 1988; accepted 19 August 1988)     

EASTERN MEDITERRANEAN OPISTHOBRANCHIA: RUNCINIDAE (RUNCINACEA), WITH A REVIEW OF RUNCINID CLASSIFICATION AND A DESCRIPTION OF A NEW SPECIES FROM FIJI

An account is given of the runcinaceans Runcina adriatica, R.brenkoae and R. zavodniki collected on diving expeditions inthe northern Adriatic Sea. The new data permit a clear separationof these from other runcinaceans of the north Atlantic Ocean.Several diagnostic features of the radulae and the oral cuticu-lararmature are corrected or amplified. Dental metamorphoses aredescribed for R. adriadca and R. zavodniki. The world's runcinaceanfamilies, genera and species are reviewed, and Runcina fijiensisn.sp. is described from the Pacific island of Viti Levu, Fiji (Received 14 December 1987; accepted 7 January 1988)     

Radula formation in two species of Conoidea (Gastropoda)

The radula is the basic feeding structure in gastropod molluscs and exhibits great morphological diversity that reflects the exceptional anatomical and ecological diversity occurring in these animals. This uniquely molluscan structure is formed in the blind end of the radular sac by specialized cells (membranoblasts and odontoblasts). Secretion type, and the number and shape of the odontoblasts that form each tooth characterize the mode of radula formation. These characteristics vary in different groups of gastropods. Elucidation of this diversity is key to identifying the main patterns of radula formation in Gastropoda. Of particular interest would be a phylogenetically closely related group that is characterized by high variability of the radula. One such group is the large monophyletic superfamily Conoidea, the radula of which is highly variable and may consist of the radular membrane with five teeth per row, or the radular membrane with only two or three teeth per row, or even just two harpoon-like teeth per row without a radular membrane. We studied the radulae of two species of Conoidea (Clavus maestratii Kilburn, Fedosov & Kantor, 2014 [Drilliidae] and, Lophiotoma acuta (Perry, 1811) [Turridae]) using light and electron microscopy. Based on these data and previous studies, we identify the general patterns of the radula formation for all Conoidea: the dorsolateral position of two groups of odontoblasts, uniform size, and shape of odontoblasts, folding of the radula in the radular sac regardless of the radula configuration. The morphology of the subradular epithelium is most likely adaptive to the radula type.     

Indirect evidence for ecophenotypic plasticity in radular dentition of Littoraria species (Gastropoda: Littorinidae)

In examination of radulae from all but one of the 36 speciesof the littorinid genus Littoraria we found extraordinary intraspecificvariation in those occurring on a range of substrates. Radulaefrom rock showed a less well developed `hood' on the rachidiantooth, a strikingly enlarged major cusp on each of the fivecentral teeth, fewer cusps on the outer marginal teeth and theradular ribbon was longer, when compared with radulae of conspecificsfrom plant substrates. The radulae of species found exclusivelyon rock differed in similar ways from those restricted to plantsubstrates (mangroves, driftwood and saltmarsh). We suggestthat this may be an example of phenotypic plasticity of radularform, induced by substrate and/or diet, as recently shown experimentallyin another littorinid genus. The mechanism of inducible plasticitydeserves further study. Ecotypic variation in the radula maybe widespread in littorinids, and radular characters shouldtherefore be used with caution in studies of taxonomy, phylogenyand adaptation. (Received 20 July 1998; accepted 10 November 1998)     

Egg capsules, eggs and embryos of the southwestern Atlantic gastropod Coronium coronatum (Gastropoda: Muricidae)

The egg capsules, eggs and embryos of the muricid gastropodCoronium coronatum are described for the first time. Capsulesare sessile, bulliform, semi-circular, with a plug in the dorsalcenter. Sutures split the capsule into two asymmetrical halves.Recently laid capsules showed the presence of 3639 (n = 2) uncleavednurse eggs with a diameter of 180–210 µm (mean= 197.4 ± 8.9). The number of early embryos was 9–11.The size of the embryos was 320 x 320 to 820–880 µm.Nine pre-hatching embryos of 3.94 mm (n = 8, SD = 0.32)were found inside the older capsule. SEM illustrations of embryosand radulae are provided. Comparison of shell and radula ofembryos with the protoconch and radulae of adults of C. coronatumrevealed that the capsule belongs to this species. (Received 18 March 2006; accepted 10 October 2006)     

NEW SPECIES OF THAIS (NEOGASTROPODA, MURICIDAE) FROM SINGAPORE, WITH A RE-DESCRIPTION OF THAIS JAVANICA (PHILIPPI, 1848)

The intertimdal gastropod Thais malayensis n.sp. (Neogastropoda,Muncidae) is described from Singapore and peninsular Malaysia.Although a common species, it may have been previously overlookedor mistaken for other species found in and near mangroves. Anotherpoorly known species, T javanica (Phdippi) may also have beenconfounded with the new species. New data on their soft parts,radulae, opercula, and egg capsule morphology are presentedto distinguish between these closely related species. (Received 26 February 1996; accepted 15 May 1996)     

A New Genus and Species of the Family Anulidentaliidae (Scaphopoda: Dentaliida) and its Systematic Implications

Shell, radula, and anatomy of Epirhabdoides ivanovi new genusand species are described from a sample of the Russian VitjazExpedition from the Japan Trench. It is distinguished from thesimilar Laevidentalium sominium by shell morphometrics and radulamorphology. The radula is almost identical with that of Anulidentaliumbambusa (Anulidentaliidae). The anatomy of the mantle margins,however, including dorsolateral slits at the anterior mantlemargin and a connective tissue bolster at the posterior mantleopening is that of the family Rhabdidae. In a parsimony analysisEpirhabdoides ivanovi takes an intermediate position betweena basal grade of Gadilinidae and the remaining Dentaliida implyingconvergent evolution of mantle characters. An alternative butless parsimonious tree with E. ivanovi as sister taxon to Rhabdusrequires convergences in radula characters. This is the firstdocumented case of convergent anatomical features among Scaphopodaand enhances the need of radula and soft part investigationof the conchologically little informative, smooth-shelled dentaliidgroups. (Received 16 March 1998; accepted 1 June 1998)     

Key innovations in Mesozoic ammonoids: the multicuspidate radula and the calcified aptychus

A nearly complete radula with seven elements per row preserved inside of an isolated, bivalved, calcitic lower jaw (= aptychus) of the Late Jurassic ammonite Aspidoceras is described from the Fossillagerstätte Painten (Bavaria, southern Germany). It is the largest known ammonite radula and the first record for the Perisphinctoidea. The multicuspidate tooth elements (ctenodont type of radula) present short cusps. Owing to significant morphological differences between known aptychophoran ammonoid radulae, their possible function is discussed, partly in comparison with modern cephalopod and gastropod radulae. Analogies between the evolution of the pharyngeal jaws of cichlid fishes and the ammonoid buccal apparatus raise the possibility that the evolution of a multicuspidate radula allowed for a functional decoupling of the aptychophoran ammonoid jaw. The radula, therefore, represents a key innovation which allowed for the evolution of the calcified lower jaws in Jurassic and Cretaceous aptychophoran ammonites. Possible triggers for this morphological change during the early Toarcian are discussed. Finally, we hypothesize potential adaptations of ammonoids to different feeding niches based on radular tooth morphologies.     

FEEDING PATTERNS OF FISSURELLA SPECIES ON ISLA DE MARGARITA, VENEZUELA: USE OF RADULAE AND FOOD PASSAGE RATES

Structural differences and functional wear of the radula inthree species of the gastropod Fissurella from Isla de Margarita,Venezuela, were examined using light and electron microscopy.Wear patterns indicate between 6 and 9 transverse rows of teethare comonly used during feeding. Mechanical wear was most noticeableon the cusps of the outer lateral tooth; this wear varied fromrounding (F. nimbosa) to blunting (F. barbadensis) to squaring(F. nodosa) of the cusps. Morphological changes were additionallycharacterized by a significant decrease in the cusp length ofmarginal cusps in F. nodosa and breakage of the central toothand inner lateral teeth in F. barbadensis. Interspecific differencesin wear patterns suggest that the rhipidoglossate radula maybe used differently by congeneric Fissurella. Despite considerable variation, rasping rates while feedingon the same substrate were comparable among species; however,food passage rates through the digestive system differed amongspecies studied. Fissurella barbadensis requires 12 hours topass its food through the digestive tract, taking almost twiceas much time as F. nodosa and F. nimbosa. These data highlightdifferences in the feeding ecology of Fissurella species andcorrelate well with individual activity patterns and grazinghabits. ^*Present address: La Salle University, Department of Biology,20th Street at Olney Avenue, Philadelphia, PA 19141, USA. (Received 4 October 1988; accepted 16 February 1989)     

FRESHWATER SNAILS OF THE BULINUS TRUNCATUS/TROPICUS COMPLEX IN KENYA: TETRAPLOID SPECIES

Studies in recent years on chromosome number in freshwater snailsbelonging to the Bulinus truncatus/tropicus complex demonstratedthe occurrence in Kenya of one diploid species, B. tropicus,and 2 tetraploid species, B. truncatus and B. permembranaceus.Further observations are now described on the morphologies ofthe tetraploid species, and their distributions. Observations were made on B. truncatus from 26 localities (11newly reported) and B. permembranaceus from 26 localities (7newly reported), in respect of chromosome number, egg proteins,enzymes (5 systems), shell (10 variables measured), male genitalsystem (normal or aphallic) and radula (1st lateral tooth, sizeand mesocone shape). B. permembranaceus differs most clearly from B. truncatus inegg proteins, enzyme-loci and in lacking aphallic individuals.Mesocone shape is generally less angular in B. permembranaceus.The shell of B. permembranaceus grows larger, has the columellamore commonly concave and its spire is proportionally higherand more acute. To distinguish these tetraploid species fromthe partly sympatric B. tropicus, observations on chromosomenumber and biochemical characters are necessary. The tetraploids are allopatric, B. truncatus being found rarelyas high as 1900 m altitude, whereas B. permembranaceus occupiesthe altitude range 1940–2760 m. B. truncatus may be expandingits distribution in Kenya in man-made waterbodies, while B.permembranaceus possibly is restricted by adaptation to coolconditions and by interaction with B. tropicus. Differencesbetween B. truncatus and B. permembranaceus, both morphologicaland biochemical, indicate their origins lie in independent episodesof tetraploidy. ^*Member of External Scientific staff, Medical Research Council (Received 31 October 1988; accepted 6 December 1988)     

PAGODATROCHUS, A NEW GENUS FOR MINOLIA VARIABILIS H. ADAMS, 1873 (GASTROPODA: TROCHIDAE)

Nomenclaturel confusion surrounding the name Minolia variabilisH. Adams, 1873 is clarified. Joint consideration of overallshell morphology and radula structure indicates previous subfamilialand generic referral of the taxon to be incorrect. This necessitatesthe proposal of Pagodatrochus gen. nov. which is provisionallyplaced in the Gibbulinae. Trochus mariei Fischer, 1886, andMinolia eutyches Melvill, 1918, are shown to be synonyms. Lectotypesof the following species are designated and figured: M. eutyches,Gibbula holdsworthana G. & H. Nevill, 1871, and Vanitrochustragema (Melvill & Standen, 1896); the holotype of Trochusmariei is also figured. Minolia charmosyne Melvill, 1918, issynonymised with Gibbula holdsworthana G. & H. Nevill, 1871. (Received 24 April 1988; accepted 26 May 1988)     

NOTES ON SOME IBERO-MOROCCAN AND MEDITERRANEAN TRICOLIA (GASTROPODA, TRICOLIIDAE), WITH DESCRIPTIONS OF NEW SPECIES

Three new species hitherto confused with Tricolia tingitanaGofas, 1982 are described, one from Corsica and Sicily and twofrom the Strait of Gibraltar. Distinctive characters seen onliving animals and on radulae are discussed. (Received 26 August 1992; accepted 4 January 1993)     

Radula und Fangarme beiMichelinoceras sp. aus dem Silur von Bolivien

New finds of michelinoceratid cephalopods from the Kirusillas-Shale (Ludlow/Silurian) of Ushpa-Ushpa in the Eastern Cordillera of the Bolivian Andes reveal parts of the radula and imprints of arms owing to extremely good preservation conditions. The imprints of soft parts point that the orthoce-rates had 10 arms, two of them shaped to long tentacles as recent coleoids have. Of more importance is the first proof of a michelinoceratid radula in situ. This is the first known ra-dula of lower palaeozoic cephalopods at all. TheMichelinoceras radula consisted of 7 teeth per row. So the radulae of michelinoceratid cephalopods are very similar to those of ammonites and coleoids. But there are great differences in the radula ofMichelinoceras sp. and that ofNautilus sp. All known radulae of fossil and recent cephalopods are compared and phylogenetic or systematic implications are discussed. The classification of the cephalopods into six subclasses as used in the “Treatise” turns out to be unnatural and should be given up. Finally ecological relations between the morphology of radula-elements and mode of life are dis-cussed. Size and number of radula teeth let suppose that thisMichelinoceras specimen must have been an adult individual living far off the coast in pelagic seas.     

RADULAR PRODUCTION RATES IN TWO SPECIES OF LACUNA TURTON (GASTROPODA: LITTORINIDAE)

The molluscan radula is a dynamic organ, both in terms of itsuse and production. New rows of teeth are constantly producedat the posterior end of the radula, while older, worn teethare shed anteriorly, producing a dynamic equilibrium. We useda cold-shock to mark the radular ribbon and measure tooth rowproduction rates in two gastropod species, Lacuna vincta (Montagu)and L. vanegata Carpenter. We found that the average tooth rowproduction rate at 10–11°C did not differ betweenthese two species, and was 2.94 (SE = 0.002) rows per day forLacuna vincta and 2.97 (SE = 0 002) for L. vanegata Inter-individualvariability in production rate was very low, and was correlatedwith shell length, smaller individuals had slightly higher productionrates. The total length of the radular nbbon varied greatlyamong individuals, ranging from 47 to 94 (2.57 to 5.68 mm) rowsin L vincta and 53 to 99 rows (2.80 to 7.14 mm) in L vanegata,and was only somewhat correlated with the length of the shelLThis great variability will result in large differences amongindividuals in the time it takes to replace the radula totally,from 14.96 to 35.44 days in L vincta and from 17 43 to 39 69days in L. vanegata. (Received 1 September 1995; accepted 20 November 1995)     

THE GENUS HAMINOEA (GASTROPODA: CEPHALASPIDEA) IN PORTUGAL, WITH A REVIEW OF THE EUROPEAN SPECIES

The study of specimens of Haminoea collected on the coast ofPortugal, together with the re-evaluation of historical specimensused by Nobre (1938–40) in his main work on the Portuguesemolluscs, recognized the presence of two species, Haminoea navicula(da Costa, 1778) and H. orbignyana (Férussac, 1822),and confirmed the misidentification of H. orbignyana as H. elegans(Gray, 1825). Anatomical analysis found intraspecific variabilityin the radula of H. navicula and H. orbignyana and in the seminalduct of the latter. The systematic value of taxonomic featuresincluding the shell, external morphology, animal coloration,radula, jaws, gizzard plates, prostate gland, seminal duct,penis and egg-masses is discussed. For all European speciesbut H. orbignyana, identification is only possible when anatomicaldata are considered, and the most relevant character is themale reproductive system. SEM images of the penis and prostateof H. navicula and H. orbignyana are given for the first time.A synoptic table for the recognition of the European speciesis provided. (Received 21 January 2005; accepted 17 June 2005)     

THYSANODONTINAE: A NEW SUBFAMILY OF THE TROCHIDAE (GASTROPODA)

New genera Thysanodonta, Carinastele and Herbertina are referredto a new subfamily of the Troch-idae, Thysanodontinae, on thebasis of extremely distinctive jaw and radula. At up to 1400times longer than broad, the teeth are the most slender of anyknown gastropod, and they are unique among archae-ogastropodsin having harpoon-like tips with back-wardly inclined barbs.While food and feeding mode are unknown, it is suggested thatthey feed suctorially, perhaps on cnidarians. New species describedare Thysanodonta aucklandica, T. wairua, Carinastele kristelleae,C. jugosa, and C. coronata from New Zealand, T. boucheti fromNew Caledonia, and Herbertina eos and H. cognata from SouthAfrica. The Tasmanian Basilissa nicetarium Hedley & Mayis tentatively referred to Carinastele (Received 23 September 1987;     

MAINWARINGIA NEVILL, 1885, A LITTORINID GENUS FROM ASIATIC MANGROVE FORESTS, AND A CASE OF PROTANDROUS HERMAPHRODITISM

On the basis of reproductive anatomy and radula, the poorlyknown genus Mainwaringia Nevill, 1885, is shown to belong tothe Littorinidae. The genus is represented by two species, M.leithii (E.A. Smith, 1876) from India to Vietnam, and a newspecies, M. rhizophila, from Malaysia to Hong Kong. Both occurin mangrove forests. The reproductive anatomy of M, rhizophilais described in detail, and it is interpreted as a protandroushermaphrodite, a condition unique in the Littorinacea. In theintersexual and female stages both closed pallial oviduct andopen prostate are present in the mantle wall, suggesting thatthese structures are not strictly homologous. The affinitiesof Mainwaringiaare discussed, and it is concluded that it maybe most closely related to Littorina s.s. (Received 30 May 1986;