Tag Archives: achatinidae

New Brazilian Rectobelus

A paper published last year describing a new species from Brazil is Simone & D’ávila. “Rectobelus levogyrus, a new species of subulinid, is described found in archaeological surveys in Amazon shell mounts (sambaquis) from Costa Marques, Rondônia, Brazil. It is the first sinistral subulinid species recorded in Brazil, and that is its main distinguishing character. A brief taxonomical treatment of the other congener species, R. rectus (Baker, 1927) (the type species, from Venezuela) and R. birabeni (Hylton Scott, 1946) (from Argentina) is included, with figures, as well as a discussion on the validity of the genus“.

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The title of this papers is curious, citing two different subfamily names, which are both outdated as the Subulininae are now considered as belonging to the Achatinidae. This is a very difficult group as the species are separated on minor details which are often not consistently studied in larger series. Many species from the ‘subulinid’ group are supposed to have continuous growth, making size differences difficult to use as a taxonomic characteristic. Moreover, for many species anatomical and molecular data are lacking. In this paper Simone disagrees with the opinion of Hausdorf, who considered Rectobelus H.B. Baker. 1927 as a synonym of Ischnocion Pilsbry, 1907. The latter is placed on MolluscaBase in the subfamily Coeliaxinae. Thus there remains ample room for further research.

Reference:
Simone, L.R.L. & D’ávila, 2019. The discovery of a sinistral Obeliscinae (Eupulmonata, Subulinidae) in Brazil, found in Amazon archaeological shell mounds of Rondônia. – Journal of Conchology 43(4): 327-336.

Brazilian Obeliscus

Recently published by D’Avila e.a., a paper on Brazilian Obeliscus species. The abstract reads as follows: “Obeliscus agassizi Pilsbry, 1906 was described from specimens collected in Brazil, by J. G. Anthony, during the Agassiz expedition, in 1865. The type locality of the species was given simply as Brazil, without further information. More than a century after its description, this species was rediscovered during an expedition to the Biological Reserve of Pedra Talhada, Alagoas/Pernambuco states, Brazil. In the present study we provide detailed description of the anatomy of the soft parts of O. agassizi specimens, collected during this expedition, besides more precise data concerning the species occurrence. This work presents the first anatomical description for the genus. An annotated checklist of Obeliscus Beck, 1837 species is also provided. The species of Obeliscus have been traditionally distinguished by shell characteristics, mainly the general shell shape, number of whorls proportionally to the shell size, shell ornamentation, the shape of the protoconch and aperture size and shape. The distinction between species is often subtle. Considering that shell traits may be not sufficient as single taxonomic characters, other evidence for species boundaries, especially anatomical characters, is needed. Presently, it is not possible to discuss the taxonomic meaning of the set of anatomical characters described for O. agassizi, at the intra-genus level, as there is no information on the anatomy of the soft parts of other species of Obeliscus. The comparative analysis of the genital system of O. agassizi, Neobeliscus calcareus (Born, 1780), Stenogyra terebraster (Lamarck, 1822) and Rectobelus birabeni (Hylton-Scott, 1946) pointed out anatomical characters with potential diagnostic significance for the genus Obeliscus. However, the establishment of a definitive dif- ferential diagnosis for this genus, based in both conchological and anatomical traits, depends on the analysis of a greater number of species of Obeliscus, as well as species of other genera of Obeliscinae Thiele, 1931“.

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This is a useful paper, especially by providing anatomical details for this species and a checklist of other Brazilian species of the genus. However, the authors have missed the chance to add also molecular data to place this genus in the phylogentic data already available for the family. According to MolluscaBase the genus Obeliscus is classified in the Achatinidae (subfamily Stenogyrinae), no longer in the Subulinidae (subfamily Obeliscinae).

Reference:
D’ávila e.a., 2020. Resdiscovery of Obeliscus agassizi Pilsbry, 1906 (Gastropoda, Subulinidae, Obeliscinae), annotated checklist of species of Obeliscus beck, 1837 and first description of the anatomy for the genus. – Zoosystema 41(12): 159-172.

Snails from Fernando de Noronha

Recently published by Freitas et al., a survey at this archipelago. “Oceanic island biotas are known by their high levels of endemism and high vulnerability. In Brazil, only few islands have been studied. The present study reports general information on the distribution and abundance of terrestrial gastropods of the Fernando de Noronha archipelago, a group of islands 345 km off the Brazilian coast. In total, four species of land snails were recorded: the endemics Hyperaulax ridleyi (Smith, 1890) and Ridleya quinquelirata (Smith, 1890), and the widely distributed Beckianum beckianum (Pfeiffer, 1846), and Allopeas gracile (Hutton, 1834). The most abundant species was H. ridleyi. By reporting the present situation of native land snails of Fernando de Noronha, this study provides data that could help in their conservation, comprising an important first step for planning future conservation strategies for the land biota of the whole archipelago“.

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Reference:

Freitas, A.V.L. et al., 2019. Land snails of the Fernando de Noronha archipelago, Brazil. – American Malacological Bulletin, 37(2): 66-69.

Achatina in Ecuador

Earlier this year a paper by Cuasapaz-Sarabia & Salas presented results about the occurrence of Achatina fulica in a private nature reserve. “Achatina fulica is an invasive terrestrial gastropod known as one of the 100 most harmful invasive species in the world. Achatina fulica is known in Ecuador since 2008, but the impact over their native ecosystems has not evaluated. The main objective was to determine the home range (HR) of this species in two zones with different levels of intervention in the Cerro Blanco reserve. The field work consisted in the capture, marking, recapture, taking of morphometric measurements and georeferencing of the individuals; for the analysis of data, HR was calculated using the convex polygon method, and environmental variables were correlated through a principal component analysis (PCA). The average HR in the altered zone was 3.58 m2 (± 0.93, n = 30), and on the ecotourist trail was 3.27 m2 (± 0.48, n = 40); the humidity was the environmental parameter that directly influences the life area and the population density in both zones study. The management of this invasive species does not appear as a key management issue for this private reserve, so it is recommended a control actions for its eradication“.

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It is remarkable that – although the occurrence of this species in Ecuador is known for more than 10 years – eradication programs seem to be lagging behind. And even (private) nature reserves are not alarmed about it. Thus the risk of spread of this important pest species is still prevalent. A serious issue…

Reference:
Cuasapaz-Sarabia, J. & Salas, J.A., 2019. Área de vida de la especie invasora Achatina fulica (Gastropoda: Achatinidae) en un área de conservación de bosque seco ecuatoriano. Revista peruana de biología 26(1): 41 – 48.

A new subulinid from Argentina

A paper that escaped my attention until now, is by Miquel & Jaime (2018) describing a new species from Argentina. “The presence of two Subulinidae living in the tropical region of Argentina is recorded: Nannobeliscus mariaisabelae spec. nov. and an indeterminated species of Leptinaria. N. mariaisabelae is characterized by turrited shell, radular formula 17+1+17 with tricuspid teeth, penis with verge and epiphallus (producing spermatophores); vagina long, with one medial bulb; ovoviviparous. Leptinaria spec. is known only for its small shell, conical, perforated, with strong axial ribs, columella not truncated, amber-yellowish“.

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Based on anatomical data the authors argue that Nannobeliscus deserves to be raised to generic status. The genus is thus known from Argentina and Central Peru (where is was described from by Weyrauch), but undoubtedly more taxa in intermediate regions may be grouped with it.
Reference:
Miquel, S.E. & Jaime, G.L., 2018. Subulinidae species from northern Argentina with description of a new species of Nannobeliscus Weyrauch (Gastropoda, Stylommatophora, Achatinoidea). Spixiana, 41: 1–7.

Shells and bones

Found by serendipity: a forensic medicine study on the association of terrestrial shells with a buried skeleton (Galvão et al., 2015). As this is the first report of such an association and the crime case was in Brazil, it seems apt to report here.

The abstract reads as follows: “Little is known regarding the scavenger fauna associated with buried human corpses, particularly in clandestine burials. We report the presence of 20 shells of the terrestrial snail Allopeas micra, within hollow bones of human remains buried for 5 years, during the process of collecting DNA material. The fact that a large number of shells of A. micra had been found in the corpse and in the crime scene supports the assumption that there was no attempt to remove the corpse from the area where the crime occurred. Despite this, our observations cannot be used to estimate the postmortem interval because there is no precise knowledge about the development of this species. This is the first record of a terrestrial snail associated with a human corpse and its role in this forensic medicine case“.

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One of the co-authors was Luiz Simone, who also made the identification of the shells. Earlier studies on forensic malacology were focussed on marine species, and so this was an interesting case.

Reference:
Galvão M. et al., 2015. Shells and bones: A forensic medicine study of the association of terrestrial snail Allopeas micra with buried human remains in Brazil. – Journal of Forensic Sciences 60: 1369-1372.

New Cuban species

A while ago (December 2017) Espinosa et al. published a paper which only now surfaced. Its abstract is extremely short, even not mentioning the names of the new species they described. “A commented and illustrated catalog of 37 land an freshwater mollusks species from Cupeyal del Norte, Alejandro de Humboldt National Park, Guantánamo, Cuba, is presented, 18 of them are new records to the park and 8 are described as new species, and data’s about others land mollusks species of the Park are included”.

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The new taxa introduced are:

[Helicinidae:] Emoda poeyana

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[Annulariidae:] Diplopoma (Subannularia) mucaralense

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Annularisca (Annularella) haylerae

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[Urocoptidae:] Arangia humboldtiana

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Carcinostemma silvai

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[Achatinidae:] Obeliscus (Stenogyra) diegoi

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[Cepolidae:] Coryda thierryi

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Coryda carabelloi

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Reference:
Espinosa J., Herrera-Uría J. & Ortea J., 2017. Moluscos terrestres y fluviales del Sector Cupeyal del Norte, Parque Nacional Alejandro de Humboldt, Guantánamo, Cuba, con la descripción de nuevas especies. – Revista de la Academia Canaria de Ciencias, 29: 61-110.

New Subulinid from Brazil

Freshly pressed, a new genus and species from Brazil. Simone’s abstract reads “Lavajatus moroi is a new genus and species found in cave environment from Santa Quitéria region, Ceará, Brazil. It is mainly characterized by the very elongated shell measuring about 30 mm, the growth is uniform, adult shell of ~28 whorls, and the shell profile is rather straight. The species has an extraordinary capacity of retraction inside the shell, keeping empty from 1/3 to 1/2 of the shell length when retracted. Anatomically, lung lacking developed vessels; ureter entirely tubular; kidney wide, with narrow anterior projection; genital structures mostly located inside anterior half of the haemocoel; lack of jaw, esophagus very narrow; large pair of retractor muscles of buccal mass (m2), with a branch passing through the nerve ring; odontophore lacking horizontal muscle (m6), with cartilages ~3/5 fused with each other; spermoviduct having two regions, being the anterior one normally bearing young specimens; and nerve ring having a large visceral/ subesophageal ganglion. The dissection of the intrauterine young specimens, which normally have a swollen head and a posterior pedal flap, revels some interesting ontogenetic features, such as the extreme elongation of some structures, e.g., the lung and digestive tubes, the repositioning of some haemocoel structures, and the modification of the nerve ring (appearance of the pleural ganglia, fusion and migration towards anterior of the subesophageal ganglia) during the development. Comparison with known subulinines is performed, including accounts on the youth intrauterine development. The new species is almost troglobian, except for the presence of eyes”.

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As usual, there are many detailed drawings of the anatomy. The author has a specific, actual etymology for the genus name: “The generic name is a Latinization of the Portuguese words Lava Jato (car wash), an allusion to the Lava-Jato Operation, which designates a conjunct of investigations of Federal Police of Brazil, mostly investigating corruption crimes. The translucency of the shell, revealing the occult inner structures, is an afflatus”. Also the specific epithet is related to this: “The specific epithet is in honor to the judge Sérgio Fernando Moro, professor of criminal law in Federal University of Paraná, who is leading Lava-Jato Operation referred above. This is a demure acknowledge of his effort in remodeling Brazil into a better country”.

Sometimes scientists try to make pinholes in the actual world; this is how far a taxonomist can go….

Reference:
Simone, L.R.L., 2018. Lavajatus moroi, new cavernicolous Subulininae from Ceará, Brazil (Gastropoda, Eupulmonata, Brazil). – Spixiana, 41 (2): 173-187.

 

Life history of subulinids

Just published: a paper on the life history of some subulinid species by D’ávila et al. The abstract reads: “In the present study, we aimed to characterize the life history of the land snail Subulina octona integrating information on life- history traits and morphology. We also compared the histology of the free-oviduct and spermoviduct of ovoviviparous and egg-retaining species of subulinids. We considered as ovoviviparous the species in which the complete embryonic development as well as egg hatching occurs inside the parent’s body and, at the end of this process, the parent releases juveniles instead of eggs. We considered as egg-retaining the species in which a great part of the embryonic development takes place inside the parent’s body and the eggs laid contain well-developed embryos. The results showed that the free-oviduct of both ovoviviparous and egg-retaining species shows a histological arrangement that confers greater strength to its walls and is probably related to egg retention. The wall of the spermoviduct is formed by pseudostratified columnar epithelium, with cell apical processes (probably cilia), and by underlying secretory cells. In gravid egg-retaining snails, the eggshells appear in close contact with the secretory cells of the spermoviduct. This fact suggests that these cells play a role in eggshell formation. The present study is the first account for histological features of S. octona, Allopeas gracile and Allopeas micra. The life history of S. octona is a combination of long life-span, early sexual maturity, indeterminate growth and egg reten- tion. Egg retention limits the number of young that can be produced in one reproductive event. However, the reproductive strategy adopted by S. octona, associating egg retention and K-strategism, compensates this cost of retaining eggs, because the reproductive success may be enhanced as a result of the higher survival of juveniles and the possibility of performing sev- eral reproductive events during the year”.

Since there are too many papers on the life history of land snails, this a welcome contribution. Especially since these subulinids are wide-spread, this paper is also of interest to non-Neotropical malacologists.

Reference:
D’ávila, S. et al., 2018. Life history of Subulina octona (Brugüière) (Gastropoda: Pulmonata: Subulinidae) based on four-year laboratory observations and a comparative histological analysis of egg-retaining and ovoviviparous subulinids. – Journal of Natural History 52 (23-24): 1551-1569.