Wide Umbilicus Research Articles

Two new species of the carnivorous snail genus Sinoennea Kobelt, 1904 (Eupulmonata: Diapheridae) from Laos

ABSTRACT Two new species of carnivorous microsnails in the genus Sinoennea Kobelt, 1904, from Laos, are described herein. Sinoennea bounphanmyae Inkhavilay and Vanhdibay sp. n. from Vientiane Province is characterised by an ovate and nearly smooth-surfaced glossy shell, ear-shaped aperture, apertural dentition with five folds (parietal, two palatal, and two columellar), and a wide umbilicus with a periumbilical groove. The other species, S. houaphanica Inkhavilay, Inthavong and Oulaiseng sp. n. from Houaphanh Province, is characterised by an ovate cylindrical, glossy, and ribbed shell; rounded aperture; parietal callus not elevated; apertural dentition with three folds (parietal, lower palatal, and columellar); and a narrow umbilicus with swelling on the inner part of the last whorl. The discovery of these two species has increased the number of recorded Sinoennea snails in Laos to nine species. http://www.zoobank.org/urn:lsid:zoobank.org:pub:6832DD40-F7B0-4CDC-8EEA-A809C3FFC3B3

A new species of Lysinoe (Gastropoda: Helicoidea) from the Oligocene of Mexico

In her 1945 study on the Tertiary fossil mollusks of northeastern Mexico, Gardner listed only 2 taxa of land snails: Holospira eva Gardner, 1945 and “Helix” sp. The latter is recognized here as a new species of Lysinoe Adams & Adams, 1855 (Helicoidea, Xanthonychidae). The new species can be diagnosed from its congeners by its flattened shell profile, a lower body whorl with a faint angulation on its median portion, a ridge-like angulation around the umbilicus, and a likely wide umbilicus. The species is known to occur in 2 nearby Upper Middle Oligocene outcrops in the eastern part of the state of Nuevo León.

Molecular phylogeny and morphological evolution of the Chinese land snail Cathaica Möllendorff, 1884 (Eupulmonata: Camaenidae) in Shandong Province, China

Abstract Cathaica is a genus of bradybaenid land snails occurring in China and is widespread in Shandong Province. Here we re-describe three species, C. pyrrhozona, C. fasciola and C. leei, and describe two new species, Cathaica fohuiensis Zhang sp. nov. and Cathaica multicostata Zhang sp. nov.. Geometric morphometric analyses demonstrate that C. pyrrhozona, C. fasciola, C. leei and C. fohuiensis are conchologically similar. Based on differences in their genitalia and molecular data, we consider C. pyrrhozona and C. fasciola to be distinct species. This re-establishes C. pyrrhozona as the type species of Cathaica. Cathaica leei can be distinguished based on its plate spiral whorl and wide umbilicus. The new species C. fohuiensis, with a conical shell and expanded vaginal base, can be distinguished from other Cathaica species based on morphological criteria and is robustly supported in the phylogenetic tree. The other new species, C. multicostata, possesses a strongly ribbed discoid shell and exhibits mucous glands that cluster tightly with the vagina. It is robustly supported in the phylogenetic tree and is the sister taxon to the other Cathaica species. Based on morphological characters and our molecular tree, Pliocathaica, represented here by P. buvigneri, P. pulveratricula and P. gansuica, is not monophyletic.

Stapafurdius, a new genus of Bulimulidae (Mollusca, Eupulmonata) from Bahia, Brazil, with two new species

The new genus Stapafurdius gen. nov. is introduced collected from Bahia, Brazil, including two new species: S. glaber sp. nov., the type species, occurs in Ibicoara; and S. costiferus sp. nov., from Andaraí regions. The new genus includes species of about 10 mm, elongated shell, reticulated protoconch, elongated peristome, and wide umbilicus. Both species differ mainly by the sculpture, as S. glaber sp. nov. is smooth, while S. costiferus sp. nov. has strong axial sculpture. urn:lsid:zoobank.org:pub:C851695E-6BF1-4418-8D8A-8BC7D10CC2FE.

A New Species of Yezoceras (Ammonoidea, Nostoceratidae) from the Coniacian in the Northwestern Pacific Realm

A nostoceratid ammonoid Yezoceras elegans sp. nov. is newly described from the Coniacian of the Haboro area in Hokkaido, northern Japan. Yezoceras elegans sp. nov. having loosely coiled whorls, a wide umbilicus, and two prominent tubercle rows concentrated in the lower part of the whorls, is distinguished from the other species by these characteristics. Yezoceras elegans sp. nov. might have originated from Y. nodosum, judging from the stratigraphic correlation. The restricted occurrences of three Yezoceras species (Y. elegans sp. nov., Y. nodosum and Y. miotuberculatum) in Hokkaido, northern Japan suggest that the speciation of Yezoceras occurred in the northwestern Pacific realm during the Coniacian age.

Shell features associated with the sand-burying habit in gastropods

Author(s): Vermeij, GJ | Abstract: The relationship between shell form and mode of life in gastropods is important to the interpretation of fossils, but has been little explored owing, in part, to the great diversity of gastropod shells. Infaunal gastropods that actively bury in sand must conform to the demands of moving efficiently and noiselessly through a dense granular medium, but which shell characters reflect these demands and how infaunal gastropods differ from surface-dwelling (epifaunal) species remain incompletely answered questions. Here, I survey infaunal and epifaunal Indo-West Pacific members of four families (Cerithiidae, Mitridae, Costellariidae and Conidae) and consider more broadly the distribution of shell traits that confer streamlining and other potential benefits to infaunal species. Sand-burying cerithiids, mitrids and costellariids (but not conids) have on average slenderer shells than their epifaunal counterparts. The only shell features unique to sand-burying gastropods are terraced axial ribs, spiral cords or sutures, in each of which the trailing edge is steeper than the leading edge in the direction of movement; but not all infaunal gastropods have such features. An angular profile, wide umbilicus, high-relief shell sculpture and limpet-like shell is exclusive to surface-dwelling species. Specializations to the infaunal habit are more common and better expressed in the Indo-West Pacific than in tropical America.

Phenotypic plasticity can explain evolution of sympatric polymorphism in the hairy snail Trochulus hispidus (Linnaeus, 1758).

Morphological variation of snails from the genus Trochulus is so huge that their taxonomy is unclear. The greatest variability concerns forms hispidus and sericeus/plebeius, which are often considered as separate species. To evidence the species barriers, we carried out crossbreeding experiments between these two sympatric morphs. Moreover, we compared the shell morphology of laboratory-bred offspring with their wild parents to test if the variation can be explained by the phenotypic plasticity model. We found that the two Trochulus morphs show no reproductive barriers. The fecundity rates, the mean clutch size, and F1 viability observed for all crosses were not significantly different. In hybrid crosses (in F2 generation), we also recorded reproduction compatibility, similar fecundity, and hatching success as in their parents. Accordingly, phylogenetic analyses revealed the significant grouping of sequences from these different morphs and supported no constrains in reproduction between them. Comparison of shell morphology between wild and laboratory samples showed that various characters appeared highly plastic. The average shell shape of the hispidus morph changed significantly from flat with wide umbilicus to elevated with narrower umbilicus such as in the sericeus/plebeius morph. All these findings indicate that the examined morphs do not represent separate biological species and the evolutionary process is not advanced enough to separate their genetic pool. Therefore, phenotypic plasticity has played a significant role in the evolution of Trochulus shell polymorphism. The two morphs can evolve independently in separate phylogenetic lineages under the influence of local environmental conditions.

Taiwanassiminea phantasma n. sp.: a terrestrial assimineid (Caenogastropoda: Truncatelloidea) from Middle Osborn Island, Kimberley, Western Australia

A new terrestrial assimineid gastropod, Taiwanassiminea phantasma n. sp. (Truncatelloidea: Assimineidae), is described. Taiwanassiminea phantasma is characterised by its translucent, conical shell with deeply impressed sutures, spiral groove surrounding a wide umbilicus, relative lack of pigmentation and long distal penial papilla. The species differs from most assimineids in having a subcircular aperture and an operculum with a central nucleus. Taiwanassiminea phantasma has anatomical similarities to other members of Taiwanassiminea, and this relationship is supported by a partial cytochrome oxidase I mitochondrial analysis. Taiwanassiminea phantasma lives in leaf litter in vine thickets on Middle Osborn Island in northern Kimberley, Western Australia, where it is possibly endemic. No terrestrial assimineid is otherwise known from mainland Australia or its adjacent islands, including Tasmania.http://zoobank.org/urn:lsid:zoobank.org:pub:A14ACAAE-4BAD-402D-9F9D-3BC9D928411A

Divergence in the shell morphology of the land snail genusAegista(Pulmonata: Bradybaenidae) under phylogenetic constraints

The role of natural selection in phenotypic evolution is central to evolutionary biology. Phenotypic evolution is affected by various factors other than adaptation, and recent focus has been placed on the effects of phylogenetic constraints and niche conservatism on phenotypic evolution. Here, we investigate the relationship between the shell morphology and habitat use of bradybaenid land snails of the genus Aegista and clarify the causes of the divergence in shell morphology among phylogenetically related species. The results of ancestral state reconstruction showed that arboreal species have evolved independently from ground-dwelling species at least four times. A significant association was found between shell shape and habitat use, despite the existence of a certain degree of phylogenetic constraint between these traits. A principal component analysis showed that arboreal species tend to have a relatively high-spired shell with a narrow umbilicus. By contrast, ground-dwelling species have a low-spired shell with a wide umbilicus. Although the latitude and elevation of the sampling locations showed no relationship with shell morphology, the geology of the sampling locations affected the shell size of arboreal species. The development of a well-balanced shell shape is one effective method for reducing the cost of locomotion under the force of gravity in each life habitat, resulting in the divergence in shell morphology and the independent evolution of morphologically similar species among different lineages. The present study suggests that ecological divergence is probably the cause of shell morphology divergence in land snails. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 114, 229–241.

A review of the family Clenchiellidae (Mollusca: Caenogastropoda: Truncatelloidea).

The truncatelloidean family Clenchiellidae, previously treated as a tribe or subfamily of Hydrobiidae, is diagnosed as a distinct family including Clenchiella and three new genera, Coliracemata, Colenuda and Coleglabra. The family is characterised by the discoidal shell with spiral keels or cords, and a wide umbilicus. All species are found in mangrove swamps or adjacent habitats in tropical estuaries, with the exception of one riverine and one lacustrine species. Clenchiella includes the type species, C. victoriae Abbott, from the Philippines, the widespread C. minutissima (Wattebled) (= C. papuensis Benthem Jutting) from Vietnam, Singapore, Thailand, Papua New Guinea and tropical Australia, and three new species, C. bicingulata n. sp. from Singapore and Thailand, C. varicosa n. sp. from Hong Kong and Taiwan, and C. iriomotensis n. sp. from Okinawa, Japan. Coliracemata n. gen. includes C. mortoni n. sp. (type of the genus) from Hong Kong, C. katurana n. sp. from Okinawa, C. clarkae n. sp. from northeastern Australia, and tentatively C. microscopica (Nevill) and C. innocens (Preston) from India. Colenuda n. gen. consists of a single species, C. kessneri n. sp., from Northern Territory, Australia. Coleglabra n. gen. includes C. nordaustralis n. sp. (type of the genus) from Northern Territory and C. sentaniensis (Benthem Jutting) from a freshwater lake in Irian Jaya. Anatomical characters are described for nine of the twelve species. The Clenchiellidae is shown to be more closely related to Calopiidae, Tornidae, and Iravadiidae, than to Hydrobiidae.

Four new species and two new records of Odostomiinae (Gastropoda: Pyramidellidae) from Brazil

Four new species of the pyramidellid Odostomiinae from Brazil are described: Chrysallida conifera sp. nov., characterized by a small and regularly conical shell with prominent nodules; Parthenina biumbilicata sp. nov., characterized by a deep and wide umbilicus and a regularly increasing aperture diameter at the protoconch, which bears a small circular umbilicus; Eulimastoma franklini sp. nov., which is very similar to Eulimastoma dydima (Verrill & Bush, 1900) but has a prominent helicoid protoconch; Eulimastoma exiguum sp. nov., similar to Eulimastoma weberi (Morrison, 1965) but without spiral ridges. Fargoa diantophila (Wells & Wells, 1961) and Chrysallida nioba (Dall & Bartsch, 1911) are reported from the southwestern Atlantic for the first time.

Revision of genera Gaza and Callogaza (Vetigastropoda, Trochidae), with description of a new Brazilian species

A revision of the trochid genera Gaza and Callogaza, inhabiting the deep waters of western Atlantic Ocean and eastern Pacific Ocean, is here provided. Species are separated mainly by shell characters, but anatomical features are also used in some species. The species considered in this study are: Gaza compta n. sp. (SE Brazil), G. daedala Watson, 1879 (Central Pacific), G. rathbuni Dall, 1890 (tropical W Pacific), G. fischeri Dall, 1889 (E Caribbean), G. superba (Dall, 1881) (Gulf of Mexico and Caribbean), G. cubana Clench & Aguayo, 1940 (N Caribbean), G. olivacea Quinn, 1991 (NE South America and SE Brazil), Callogaza watsoni Dall, 1881 (Gulf of Mexico), C. sericata (Kira, 1959) (NW Pacific) and C. frederici (Smith, 1906) (S India). Anatomical data are provided for: Gaza compta, G. olivacea, G, fischeri, G. superba and G. cubana. Both Gaza and Callogaza are characterized by having iridescent, thin-walled shell, with the outer lip deflected (determined growth), and a flat callus partially or completely covering the wide umbilicus, making it a hollow chamber. Anatomically, the examined Gaza spp. have long epipodial tentacles and two series of holes between the propodium and the base of the head. The number of these structures can assist in the differentiation of species. Based on similarities of the shell and comparison with species of other trochid genera, we conclude that Gaza and Callogaza have some characters in common, which most probably constitute synapomorphies that support a monophyletic branch of the family. Microgaza is not regarded as part of this trochid branch, but may rather belong to Solariellinae.

Lista preliminar de los Punctoideos de Rio Grande do Sul, Brasil, con descripción de dos especies nuevas (Mollusca, Gastropoda, Stylommatophora)

Se presenta una lista parcial de gasterópodos terrestres Punctoideos del "Centro de Pesquisas e Conservação da Natureza Pró-Mata" (São Francisco de Paula, Estado de Rio Grande do Sul, Brazil) (CPCN-PM). Esta lista incluye siete especies, dos de ellas son nuevas. El CPCN-PM se localiza entre los 600 y 950 m de altitud; presenta clima templado superhúmedo a húmedo, lluvias de 2.250 mm anuales y temperatura promedio anual de 14,5ºC; están presentes tres regiones fitoecológicas principales, floresta ombrófila mixta, floresta ombrófila densa y sabana. Los taxones hallados son: Rotadiscus amancaezensis (Hidalgo, 1869), Lilloiconcha tucumana (Hylton Scott, 1963), Radiodiscus cuprinus Fonseca & Thomé, 2000, Radiodiscus tenellus Hylton Scott, 1957, Radiodiscus promatensis sp. nov., Zilchogyra gordurasensis (Thiele, 1927) y Zilchogyra zulmae sp. nov. La conchilla de R. promatensis sp. nov. es muy pequeña, casi plana, con ombligo muy desarrollado, abertura reniforme, con estrías espirales en la teleoconcha y 58-62 costillas axiales en el último anfracto. La conchilla de Z. zulmae sp. nov. es troquiforme alta, con cinco anfractos con fuertes y espaciadas costillas axiales (25-38), ombligo amplio y perspectivo y abertura subcircular angulosa. La fauna de gasterópodos carópidos del CPCN-PM tiene tres especies conocidas sólo del área (R. cuprinus, R. promatensis sp. nov. y Z. zulmae sp. nov.), una, que se distribuye también en Paraguay (R. tenellus) y tres (L. tucumana, R. amancaezensis y Z. gordurasensis), comunes a otras áreas de América del Sur, principalmente la región de las Yungas.

Miocene Vetigastropoda and Neritimorpha (Mollusca, Gastropoda) of central Chile

Species of Vetigastropoda (Fissurellidae, Turbinidae, Trochidae) and one species of Neritimorpha (Neritidae) from the Navidad area, south of Valparaı́so, and the Arauco Peninsula, south of Concepción, are described. Among these, the Fissurellidae comprise Diodora fragilis n. sp., Diodora pupuyana n. sp., two additional unnamed species of Diodora, and a species resembling Fissurellidea. Turbinidae are represented by Cantrainea sp., and Trochidae include Tegula (Chlorostoma) austropacifica n. sp., Tegula (Chlorostoma) chilena n. sp., Tegula (Chlorostoma) matanzensis n. sp., Tegula (Agathistoma) antiqua n. sp., Bathybembix mcleani n. sp., Gibbula poeppigii [Philippi, 1887] n. comb., Diloma miocenica n. sp., Fagnastesia venefica [Philippi, 1887] n. gen. n. comb., Fagnastesia matanzana n. gen. n. sp., Calliostoma mapucherum n. sp., Calliostoma kleppi n. sp., Calliostoma covacevichi n. sp., Astele laevis [Sowerby, 1846] n. comb., and Monilea riorapelensis n. sp. The Neritidae are represented by Nerita (Heminerita) chilensis [Philippi, 1887]. The new genus Fagnastesia is introduced to represent low-spired trochoideans with a sculpture of nodes below the suture, angulated whorls, and a wide umbilicus. This Miocene Chilean fauna includes genera that have lived at the coast and in shallow, relatively warm water or deeper, much cooler water. This composition therefore suggests that many of the Miocene formations along the central Chilean coast consist of displaced sediments. A comparison with different fossil and Recent faunas from around the Pacific and South America indicates that the vetigastropod and neritid fauna from the Miocene of Chile has only minor affinities with taxa living near New Zealand, Argentina, and the tropical eastern Pacific at that time.

Extensive intraspecific variation in a Triassic ammonoid from Siberia

The ammonoid species Czekanowskites rieberin.sp. from the Lower Anisian of Arctic Siberia (River Olenek) shows an enormous range of intraspecific variability. The 700 investigated specimens are packed in one single concretion. They are all adult with preserved living chambers and apertural structures. Morphologically they range from keeled smooth suboxycones with narrow umbilicus, through feebly ribbed platycones with a little wider umbilicus, to subcadicones with relatively wide umbilicus and straight ribs with bullae. The morphological variation is continuous; all specimmh belong to a single genetically linked population, variants of one biospecies. This phenomenon, which is quite common in boreal Triassic ammonoid faunas, has in the past led to serious taxonomic oversplitting. It presents a serious challenge to current ideas about a close correlation between modeof life and shell morphology in arnmonoids.□Amntonoidea, boreal Triassic, ecology. Siberia, variability.