A new Georissa (Gastropoda: Neritopsina: Hydrocenidae) from a limestone cave in Malaysian Borneo

In a previous paper, we have reported on a new, troglobiticspecies of Georissa and its possible parapatric origin fromGeorissa saulae Benthem-Jutting, 1966, which occurs outsidethe cave system of Batu Sanaron, a limestone outcrop in Sabah,Malaysian Borneo. These analyses were based on genetic and morphometricdata. Here, we formally describe the new species adding anatomicaldata derived from dissections and histological serial sectionsas well as fine structural data of shell, operculum and radula,and compare it with its stem species. The two species differin shell and radular morphology as well as genital characters.Since we found anatomical differences between very closely relatedspecies, we assume that dissections would be of general usefor the taxonomy of Georissa and the remaining nominal genus-grouptaxa of the poorly known Hydrocenidae.     

RADULAR TEETH OF INDO-PACIFIC MOLLUSCIVOROUS SPECIES OF CONUS: A COMPARATIVE ANALYSIS

Species determination in the gastropod genus Conus, heretoforeexclusively based on shell morphology and color pattern, hasled to considerable uncertainty and disagreement. We proposethat qualitative and quantitative radular tooth characters arepotentially useful in differentiating species as well as geographicsubspecies and will improve the taxonomic base. Molluscivorousspecies of Conus, sometimes placed in the subgenera Cylinder, Textilia,Darioconus, and the nominal subgenus, are taxonomically amongthe most difficult. We thus examined intra- and interspecificvariation in radular morphology of 11 of these species, C. ammiralis,C. araneosus, C. bandanus, C. canonicus, C. episcopatus, C. marmoreus,C. nodulosus, C. omaria, C. pennaceus, C. textile, and C. victoriae,and intra- and interregional variations in radular morphologyof C. pennaceus from three geographic regions. Taxonomicallyuseful qualitative characters include presence/absence of one ortwo barbs and a blade, and whether the row of denticles comprisingthe serration is continuous or interrupted. Useful metric charactersinclude the ratios of first barb, second barb, blade, serration,shaft width and base width to tooth length, the ratio of toothlength to shell length, the ratio of shaft width to base width,and the degree of curvature of the teeth. Univariate analysisof variance (ANOVA and unplanned pairwise comparison tests)distinguished 53 of the 55 possible species pairs from eachother by at least one character. Multivariate analysis of variance (MANOVA)indicated statistically significant differences between thespecies in the other two pairs. In C. pennaceus, ANOVA and unplannedpairwise tests differentiated Hawaiian from Indian Ocean samples,and MANOVA differentiated those from Maldives and Sumatra. Thediscrete radular characters sort the 11 species into three groups,and these are consistent with the distribution patterns of thequantitative characters. Radular tooth characters are thus potentiallyuseful in differentiating species and subspecies and shouldbe combined with other character sets in generating future phylogenetichypotheses. ¹ Present address: Department of Pathobiology, University of Pennsylvania,019104-6068, USA ² Author for correspondence: e-mail: kohn{at}washington.edu (Received 23 October 1999; accepted 25 January 1999)     

A NEW SPECIES OF RUNCINELLA ODHNER, 1924 (GASTROPODA: OPISTHOBRANCHIA) FROM THE GALAPAGOS ISLANDS

Runcinella thompsoni new species (Gastropoda: Opisthobranchia)is described on the basis of material collected in the GalapagosIslands. This new species differs from R. zelandica Odhner,1924, both in colour, reddish in the former, dark green withwhite freckles in the latter, and radular tooth morphology,mainly the first lateral teeth. The species is also comparedwith other red runcinids both from Atlantic and Pacific localities. (Received 28 October 1991; accepted 4 January 1993)     

SYSTEMATICS OF POTAMACMAEA FLUVIATILIS (BLANFORD): A BRACKISH WATER PATELLOGASTROPOD (PATELLOIDINAE: LOTTIIDAE)

Potamacmaea fluviatilis (Blanford, 1867), which is known fromestuaries and tributaries that drain into the Bay of Bengal,was studied to assess available material, determine possiblerelationships between P. fluviatilis and other patellogastropodtaxa, and review the current state of our knowledge of thisenigmatic species. Radular and shell structure characters indicatethat P. fluviatilis is referable to the Patelloidinae Chapman& Gabriel, 1923. The radular tooth morphology of P. fluviatilisis similar to that of the wood-eating taxon PectinodontinaePilsbry, 1891; both taxa have multicuspid lateral teeth. Substantialhuman population increase and its accompanying habitat destructionin this region may have had deleterious effects on this uniquepatellogastropod. (Received 22 May 1989; accepted 25 July 1989)     

REVISION OF THE GENUS ACAVUS FROM SRI LANKA (GASTROPODA: ACAVIDAE)

The genus Acavus from Sri Lanka includes three species, Acavushaemastoma (Linnaeus), Acavus superbus (L. Pfeiffer) and Acavusphoenix (L. Pfeiffer) with two subspecies, Acavus phoenix phoenix(L. Pfeiffer) and Acavus phoenix castaneus new subspecies.The conchological and anatomical differences between these species,as well as their intraspecific variation are described. Theirdistribution is shown on maps and all locality records are listed.The presence of extensive intraspecific polymorphism, the developmentof geographical subspecies and the presumable hybridizationbetween some species show that the Acavus species are not isolatedrelict species, but that speciation is in progress and thatthe radiation of the Acavus species is probably much youngerthan the radiation of the acavid genera. The three Acavus speciesare not acutely endangered at present. In contrast to manyother land snails, there is no risk of a rapid decline of theAcavus species due to deforestation, because these species alsooccur in synanthropic habitats. (Received 22 December 1998; accepted 2 October 1999)     

COMPARATIVE MORPHOLOGY OF RADULAR TEETH IN CONUS: OBSERVATIONS WITH SCANNING ELECTRON MICROSCOPY

Radular teeth of 22 Indo-Pacific species of the genus Conus(Neogastropoda: Toxoglossa) were compared. On morphologicalfeatures all can be related to one of three known feeding modes:piscivorous, vermivorous and molluscivorous. Observations arereported on the radular teeth of six piscivores, thirteen vermivoresand three molluscivores. The radular teeth of piscivores areof two general types. In the first, two barbs and a posteriorly-directedprocess with a recurved tip are found at the anterior end. Inthe second, two barbs are located at the anterior end and theshaft is serrated for most of its length. An enlarged posteriorregion (terminal knob) is present in the first and absent inthe second. Molluscivores possess radular teeth with two anteriorbarbs and in some species a serrated shaft or terminal knob.The radular teeth of vermivores, which show much greater interspecificvariation than those of piscivores or molluscivores, are characterizedby one or two anterior barbs and in most species a serratedregion near the apex. A forwardly-projecting cone (basal spur)is usually located on the terminal knob. Piscivores and molluscivoreslack such basal spurs. The radular teeth of Conus are used toconvey a potent venom and hold prey firmly during feeding. Previouslyundescribed morphological features are noted on the teeth ofC. obscurus and C. lividus. Figured here for the first timeare the radular teeth of C. abbreviatus, C. aureus, C. catus,C. litoglyphus, C. pennaceus, C. rattus and C. sponsalis. ^*Present address: Department of Paleontology, University ofCalifornia, Berkeley, California 94720, U.S.A. (Received 2 April 1979;     

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 ANATOMY AND RELATIONSHIPS OF A MARINE VALVATOIDEAN (GASTROPODA: HETEROBRANCHIA)

The anatomy of Cornirostra (new genus) pellucida (Laseron),a marine Indo-West Pacific gastropod, is described and is shownto be similar to that of the northern hemisphere, freshwaterValvatidae. There are, however, several differences betweenCornirostra and valvatids, notably in details of the anatomyof the reproductive system, the morphology of the head-foot,the spawn and in radular characters that warrant family-levelseparation for Cornirostra. Tomura bicaudata (Pilsbry and McGinty) from Florida is alsoa member of the family. (Received 9 September 1989; accepted 30 December 1989)     

Comparative morphology of three South African Triviidae (Gastropoda: Prosobranchia) with the description of a new species

Three species of Trivia were collected from subtidal habitats in the Cape of Good Hope Peninsula, South Africa. The morphology of T. ovulata (Lamarck, 1811), T. millardi (Cate, 1979) and T. verhoefi sp. nov. is described. Each species can be distinguished by a unique pattern of mande coloration, conchological characters of the fossula and shape of the radular teeth. The central nervous system was examined and found to be of the same configuration in die diree South African spe Trivia ovulata and T. verhoefi appear to be gonochoric while T. millardi is a protandric hermaphrodite. Trivia ovulata and T. millardi also differ in the position of the receptaculum seminis. Differences in internal morphology reported in previous work and the present study are discussed. The fact that the central nervous system of Trivia is euthyneurous is reconfirmed. Trivia ovulata and T. millardi were associated with colonial tunicates as previously recorded for other members of the genus.     

PHYLLODESMIUM GUAMENSIS (NUDIBRANCHIA: AEOLIDOIDEA), A NEW SPECIES FROM GUAM(MICRONESIA)

A new species of Phyllodesmium (Aeolidoidea) from Guam (Micronesia)is described. Phyllodesmium guamensis n.sp. is characterizedby having two rows of denticles in the radular teeth, this beingdifferent from the previously described species of the genus.The shape of the teeth, however, is identical in all the speciesof the genus, and unique among aeolids. Furthermore, P. guamensispossesses a double row of cerata in the precardiac cluster andup to 10 post-cardiac ceratal rows. Also, P. guamensis showsa very dense accumulation of zooxanthellae in the ceratal digestivegland, which is ramified inside the cerata. This species feedson at least three species of the soft coral Sinularia: S. polydactyla,S. maxima and a third, undescribed species. The aeolid matchesthe colour of its prey and is cryptic on the soft coral surface. (Received 3 October 1996; accepted 28 April 1997)     

A NEW SPECIES OF ABYSSOCHRYSOS (GASTROPODA: LOXONEMATOIDEA) FROM THE OMAN MARGIN

A new species of Abyssochrysos, A. xouthos n. sp. is describedfrom south-west Oman in the northern Arabian Sea at a depth of3150 metres. This represents the first record of this genusfrom the northern Indian Ocean. Of the five previously describedextant species of Abyssochrysos A. xouthos is most similar to A.melanioides from which it differs in radular and shell characters. (Received 22 February 1999; accepted 20 May 1999)     

SYSTEMATIC REVISION OF PATELLOIDA PYGMAEA (DUNKER, 1860) (GASTROPODA: LOTTIIDAE), WITH A DESCRIPTION OF A NEW SPECIES

Patelloida pygmaea (Dunker) and its closely allied species,P. heroldi (Dunker) and P. conulus (Dunker) have caused nomenclaturalconfusion because of their variable shell morphology and distinctivehabitats. According to current nomenclature, these species ofPatelloida have been synonymized and treated as one specieswith two ecological forms. Patelloida pygmaea lives on the shellof Crassostrea gigas (Ostreidae), P. pygmaea form heroldi occurson intertidal rocks on sheltered shores and P. pygmaea formconulus is found on the shell of Batillaria multiformis (Batillariidae).Their taxonomic relationships and possible species status are,however, unclear. Using two mitochondrial genes (fragments ofCOI and 16S ribosomal RNA; total 1192 sites), we analysed 88specimens of P. pygmaea, P. pygmaea form heroldi and P. pygmaeaform conulus from 37 localities in East Asia. In the resultingmolecular phylogenetic trees, the specimens of Patelloida fallinto four clades with high bootstrap probabilities; these cladescorrespond taxonomically to P. pygmaea, P. conulus, P. heroldiand a fourth previously unrecognized taxon, Patelloida ryukyuensisn. sp., described here. A minimum-spanning network for 29 uniquemitochondrial COI haplotypes obtained from 45 specimens in thesame bay in central Japan form three distinct clusters, consistingof P. pygmaea, P. conulus and P. heroldi, respectively. Thissuggests that reproductive isolation has been established betweeneach group. A detailed examination of radular and shell morphologiesof the four taxa clarifies the morphological distinction betweenthese species. The four species form a rather young clade inthe genus Patelloida that diverged during the Pliocene. Theyprovide an example of habitat segregation in a restricted marineenvironment. (Received 21 December 2004; accepted 11 March 2005)     

MORPHOLOGICAL STUDIES OF LYMNAEID SNAILS FROM THE HUMAN FASCIOLIASIS ENDEMIC ZONE OF BOLIVIA

The taxonomic position of the Lymnaeidae from the BolivianAltiplano has been unclear. On the basis of conchological characters,some authors reported two species from this area, Lymnaea viatrix andL. cubensis while others, considering also anatomical characters,considered L. viatrix as a synonym of L. cubensis. More recentstudies demonstrated genetic identity between the Bolivian lymnaeidsand L. truncatula from the Iberian Peninsula. Populations recognizedas L. cubensis correspond to a distinct genetic group, but geneticinformation was not available for L. viatrix. In the light ofthese genetic results, a morphometric study of both the shell (usingRaupian parameters) and male reproductive system was carried outof L. cubensis from Cuba (type locality), Dominican Republic,Guadeloupe and Venezuela, and of L. truncatula from Bolivia,France, Portugal, Spain and Morocco. Syntypes of L. viatrixfrom Argentina (var. A. ventricosa) and specimens of L. viatrix(var. B. elongata) from the type locality, Peru, were also studied(conchological characters only). The conchological study showedthe presence of a large amount of variability between populations.This variability was not congruent with genetic results. Alarge amount of variability was also found using anatomicalcharacters of the male reproductive system and all of them clearlyseparate L. cubensis from L. truncatula independently from geographicalorigin. Thus anatomical characters, unlike conchological parameters,do differentiate taxonomic species inferred from genetic studies. (Received 11 September 1997; accepted 5 March 1999)     

ADELACERITHIINAE: A NEW SUBFAMILY OF THE TRIPHORIDAE (MOLLUSCA: GASTROPODA)

Adelacerithiinae is proposed for the Pliocene Adelacerithiummerulatum Ludbrook, 1941, from Abattoirs Bore, South Australia,and the Recent A. mirabilis n.sp., from off northern New Zealand,Adelacerithium species have a dextral cerithiform shell, distinctiveshell sculpture, a columellar plait, and rhinioglossate dentitionwith reversed radular cross-row configuration. Relationshipsbetween the major triphorid groups and the possibilities forcommon origin for the Triphoroidea, Ccrithiopsoidea, Cerithioidea,and the Neogastropods are discussed. (Received 21 January 1983;     

核桃扁叶甲三亚种的分类地位订正 (鞘翅目：叶甲科，叶甲亚科)

通过对核桃扁叶甲3个亚种（指名亚种Gastrolina depressa depressa Baly,淡足亚种G. depressa pallipes Chen和黑胸亚种G. depressa thoracica Baly）的比较形态学研究,结合生物学和生物地理学方面的资料,对其分类地位进行了探讨。从形态上来说,三者的上唇、下唇、后翅和爪的形态区别较小,但是触角、上颚、下颚和受精囊则存在着较大的区别,而且通过超微形态的比较,淡足亚种、黑胸亚种和指名亚种均存在着较为明显的形态区别。动物地理学研究表明,指名亚种和黑胸亚种在我国北纬25°～30°之间有地域重叠,目前仅在部分地区可以通过海拔来区分。但是对于淡足亚种而言,它的分布区与其他两个亚种有着一定的地理隔离,其间并没有重叠区的存在。因此从地理分布上而言,三者也存在着不同。通过上述讨论,本文将核桃扁叶甲三亚种恢复或提升为种,即核桃扁叶甲G. depressa Baly,黑胸扁叶甲G. thoracica Baly和淡足扁叶甲Gastrolina pallipes Chen, stat. Nov.。     

RADULAR VARIATION IN TWO SPECIES OF SPONGE-RASPING DORID NUDIBRANCHS

The damp live weight of specimens of Archidoris montereyensisand Anisodoris nobilis was found to be positively correlated( = 0.05) to the number of teeth per row, the number of rowsin the radula and the length of teeth. Covariance analyses ofthe regressions of the first two radular characteristics toweight failed to statistically separate the two species. Theseresults argue against the utility of radular information astaxonomic characters in sponge-rasping dorids. The increase in tooth size with increasing animal size was foundto be statistically divergent for these two species and wasinterpreted as being consistent with the feeding biology ofthese two species. (Received 10 March 1977;     

Microgeographic differentiation among closely related species of Biomphalaria (Gastropoda: Planorbidae) from the Andean Altiplano

Direct development and water dependence entail limited vagility in freshwater fauna. In these organisms, the population structure is probably linked to restrictions imposed by the habitat. In this study we investigate the relative contribution of processes stimulating the divergence of populations of Biomphalaria costata (Biese, 1951) and Biomphalaria crequii (Courty, 1907), two freshwater snails occurring in two contiguous and fragmented closed basins from the Andean Altiplano using mitochondrial DNA (cytochrome c oxidase subunit I) sequences, shell morphometric and radular morphology. In order to clarify the species boundaries, a third allopatric species was included: Biomphalaria aymara Valdovinos & Stuardo, 1991. Molecular analyses recovered two distinct clades: one composed of B. aymara from the Isluga swamps and B. costata from Spring 1 in Salar de Carcote, the single spring occupied by this species, and another integrated by snails from 12 springs spread across the Salar de Carcote and the Salar de Ascotán assigned to B. crequii, originally described from the Salar de Ascotán. Unlike shell morphometrics, radular morphology was informative for distinguishing these species. The division of the lineages occurred in the Late Pleistocene. A subclade that includes snails from the southernmost springs in Salar de Ascotán suggests fragmentation of the distribution of B. crequii associated with landscape discontinuities. In addition to microvicariance signals, the private haplotypes scattered around both salt spans show that close‐range dispersal is a common biogeographic process in this species. As evolutionary units, the single isolated and restricted population of B. costata has a high priority for conservation. © 2013 The Linnean Society of London