Shell shape and land-snail habitat in a Mediterranean and desert fauna

1987 ◽  
Vol 31 (3) ◽  
pp. 257-272 ◽  
Author(s):  
JOSEPH HELLER
Keyword(s):  
Land Snail ◽  
Shell Shape

Notodiscus (Charopidae) on South Georgia: some implications of shell size, shell shape, and site isolation in a singular sub-Antarctic land snail

2011 ◽  
Vol 23 (5) ◽  
pp. 442-448 ◽  
Author(s):  
P.J.A. Pugh ◽  
R.I. Lewis Smith
Keyword(s):  
East Coast ◽  
Land Snail ◽  
Shell Shape ◽  
Shell Size ◽  
Site Isolation ◽  
South Georgia ◽  
North East ◽  
Larus Dominicanus ◽  
Close Proximity ◽  
Georgia Population

AbstractMultivariate analysis shows that shells of Notodiscus sp. (Charopidae: Pulmonata) reported from South Georgia are smaller and proportionately taller than, but otherwise similar to, populations of Notodiscus hookeri (Reeve) from Iles Crozet and Iles Kerguelen. The origin of this solitary, and spatially limited, South Georgia population is enigmatic. It is confined to a remarkably small coastal lowland site which was glaciated at Last Glacial Maximum, precluding a Tertiary relict origin, and on the leeward north-east coast, ruling out post-glacial ocean rafting. The site is close to the King Edward Point settlement, yet the absence of any logistics connections with the Iles Crozet or Iles Kerguelen mitigates against anthropogenic introduction. The close proximity of the population to nests of blue-eyed shag (Phalacrocorax atriceps), Dominican gull (Larus dominicanus) and light-mantled sooty albatross (Phoebetria palpebrata) could imply the snail was originally introduced to South Georgia via these ocean transiting seabirds.

scholarly journals The operculate micro land snail genus Dicharax Kobelt & Möllendorff, 1900 (Caenogastropoda, Alycaeidae) in Thailand, with description of new species

2021 ◽  
Vol 97 (1) ◽  
pp. 1-20
Author(s):  
Parin Jirapatrasilp ◽  
Barna Páll-Gergely ◽  
Chirasak Sutcharit ◽  
Piyoros Tongkerd
Keyword(s):  
New Species ◽  
Conical Shell ◽  
Intraspecific Variability ◽  
Land Snail ◽  
Type Locality ◽  
Shell Shape ◽  
Subjective Synonym

This study reviews the Dicharax species in Thailand. Altogether ten Dicharax species are reported, four of which are new to science and described herein. They are Dicharax borealis Jirapatrasilp & Páll-Gergely sp. nov., Dicharax burchi Jirapatrasilp & Páll-Gergely sp. nov., Dicharax panhai Jirapatrasilp & Páll-Gergely sp. nov. and Dicharax pongrati Jirapatrasilp & Tongkerd sp. nov.Alycaeus davisi Godwin-Austen, 1914 is regarded as a junior subjective synonym of Alycaeus cucullatus Theobald, 1870 (= D. cucullatus) based on a similar depressed-conical shell shape, a long sutural tube and a sharp swelling behind the peristome. Furthermore, the type locality of Alycaeus pratatensis Panha & Burch, 1997 (= D. pratatensis) had to be amended. Most important characters to distinguish Dicharax species are the general shell shape and relative lengths of teleoconch regions, whereas the spiral striation of R1, the shape of swelling of R3, the outer peristome crenulation and protrusion, and the exterior opercular sculpture show large intraspecific variability.

scholarly journals Spatial distribution and morphometry of the succineid snail Succinea baconi (Pfeiffer, 1854) in India

2021 ◽  
Author(s):  
Himangshu Barman ◽  
Soujita Pramanik ◽  
Gargi Nandy ◽  
Sampa Banerjee ◽  
Gautam Aditya
Keyword(s):  
Spatial Distribution ◽  
Vertical Distribution ◽  
Shell Length ◽  
Land Snail ◽  
Shell Morphology ◽  
Shell Shape ◽  
Regression Equations ◽  
Growth Strategies ◽  
Shell Weight ◽  
Significant Difference

The spatial distribution and morphological features of the land snail Succinea baconi (Pfeiffer, 1854) (Gastropoda: Succineidae) from India were evaluated. The survey performed in gardens and bushes in Coochbehar, West Bengal, India, has made it possible to assess the abundance of the snail S. baconi on the randomly selected lemon plants (n = 18). Logistic regressions were employed to judge differences in vertical distribution, resource association and size class variation in the snails under study. Variation in shell morphology was assessed by performing the regression analysis of the sampled shells of live snails (n = 258) and vacant shells of the deceased individuals (n = 100). An overall significant difference (p < 0.05) in the vertical distribution of snails in lemon plants was observed. As to their association with resources available, snails were found to be more abundant in detritus than on living parts of the plants. The performed logistic regression revealed that the relative abundance of different S. baconi size classes was significantly different (p < 0.001). Significant correlations (p < 0.001) were found among different body size variables, with the shell length (x)-body weight (y) relationship being: y = 0.232x2.524 (for live snails) and the shell length (x)-shell weight (y) relationship being: y = 0.358x2.537 (for shells of dead snails). Various parameters of the snail shell shape could be represented through regression equations. Although reproduction and growth strategies of snails need to be explored further, the presented observations improve our understanding of the ecology of S. baconi, which may prove useful for future conservation efforts.

Phylogenetic systematics of the land snail Basedowena from the Australian arid zone: taxonomic revision with description of new taxa (Stylommatophora : Camaenidae)

2016 ◽  
Vol 30 (4) ◽  
pp. 370 ◽  
Author(s):  
Francesco Criscione ◽  
Frank Köhler
Keyword(s):  
New Taxa ◽  
Arid Zone ◽  
New South ◽  
South Australia ◽  
Taxonomic Revision ◽  
Land Snail ◽  
Shell Shape ◽  
Mountain Ranges ◽  
South Wales ◽  
Mitochondrial Phylogeny

The land snail Basedowena Iredale, 1937 currently comprises eight species that inhabit mountain ranges in the central Australian arid zone. By studying the variation in shell and genital anatomy and the differentiation in the mitochondrial markers 16S and COI, we revise the taxonomy of this camaenid and describe new taxa. We demonstrate that the current morphology-based classification has been misled by homoplasy mainly in shell shape. In fact, Basedowena as herein revised contains species with vastly different shells, which have so far been assigned to different genera. By contrast, these species have the same general genital anatomy in common and form a clade in the mitochondrial phylogeny. Based on these findings, we transfer Pleuroxia bethana, P. hinsbyi, P. elfina, P. oligopleura, P. polypleura, P. radiata, Montanomelon angatjana and Minimelon colmani to Basedowena. While Pleuroxia and Montanomelon are maintained as distinct genera, although with fewer species, the monotypic Minimelon becomes a junior synonym of Basedowena. We identify and describe three new Basedowena species (B. bicolor, sp. nov., B. holoserica, sp. nov., B. siparium, sp. nov.). A fourth new species differs substantially from all other arid zone camaenids and is hence placed in a new genus, Xeromelon, gen. nov. The revised delineation of Basedowena renders it now the most widespread camaenid genus in Australia. It is distributed throughout the Australian arid zone from Western Australia, via the Northern Territory and South Australia into New South Wales.

Found, forgotten, and found again: systematics and distribution of Cooper’s Rocky Mountain snail (Oreohelix cooperi) on a sky island in the Canadian Prairies

2019 ◽  
Vol 97 (9) ◽  
pp. 833-840 ◽  
Author(s):  
Z.W. Dempsey ◽  
T.M. Burg ◽  
C.P. Goater
Keyword(s):  
Great Plains ◽  
Sequence Data ◽  
Conservation Status ◽  
Morphological Characteristics ◽  
Rocky Mountain ◽  
Land Snail ◽  
Shell Shape ◽  
Sky Islands ◽  
The North ◽  
Sky Island

The results of phylogeographic and biogeographic studies of organisms residing in isolated habitats provide key insights into processes of population differentiation, speciation, and endemicity. Several of the approximately 70 species of land snail in the genus Oreohelix Pilsbry, 1904 occur only on isolated sky islands on the North American Great Plains. The restricted distributions of these snails have led to concerns regarding their conservation status, particularly in western Canada where their systematics and distributions are poorly known. Cooper’s Rocky Mountain snail (Oreohelix cooperi (Binney, 1858)) has been reported from several sky islands in the northern United States. We evaluated morphological characteristics and sequence data for samples of putative O. cooperi collected from a sky island in the Cypress Hills area of southeastern Alberta and southwestern Saskatchewan. COI sequences matched O. cooperi from snails collected on sky islands in South Dakota and Wyoming and morphological analyses of shell shape and male genitalia were consistent with published descriptions of this species. COI and ITS2 sequences and morphological characteristics of these snails did not match other Oreohelix spp. found in the Cypress Hills and in the adjacent Rocky Mountains. Our results extend the distribution of O. cooperi into southern Canada and confirm its endemicity within sky islands of western North America.

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