Tag Archives: anatomy

Variability of Bostryx

Miranda published new data on the anatomy and shell shape variability of a Bostryx species. Her abstract reads as follows:
Introduction: The gastropod Bostryx torallyi shows high variability in shell shape and coloration. Subspecies of this organism have been described based on shell characters but, since they were slightly different, they were synonymized afterwards. Until now, shell variability has been analyzed only descriptively and its anatomy is still unknown.
Objective: In this study, I provide anatomical information of B. torallyi and apply a geometric morphometric analysis to evaluate the shell shape variation among specimens.
Methods: To accomplish this, type material and numerous lots were examined and dissected out. Additionally, relative warp analysis, based on 9 landmarks in ventral view of the shell, was performed using 80 specimens of 9 localities from Bolivia and Argentina.
Results: According to our results, geometric morphometrics is a suitable method to evaluate differences in shell shape among localities; for instance, distinctions in the shell were noticeable between gastropods of low and high altitudes. On the other hand, it was established that the coloration of this species is independent of large-scale factors since the examined specimens came from environments with similar conditions. Furthermore, the sculpture of the protoconch and anatomy of B. torallyi coincided with the other Argentinian species of the genus.
Conclusions: Therefore, I concluded that a geometric morphometric analysis of shell shape is a good complement to traditional qualitative description of the characteristics of the shell in this species
“.

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As this study shows, Bostryx species can be very variable in their shell shape and colouration, with their anatomy still being the same. The study indicated that altitude is possibly related to the shell shape, but this needs confirmation from material sampled in the wider distribution area.

Miranda, M.J., 2020. Anatomy and shell shape variability in a land snail Bostryx torallyi (Stylommatophora: Bulimulidae). – Revista de Biologia Tropical 68(1): 218-229.

Range extension of Bradybaena

Serniotti et al. recently published a new paper on the malacofauna of Argentina. “The Asian tramp snail Bradybaena similaris (Férussac, 1822) is an exotic mollusk native to Southeast Asia. The species has been catalogued as invasive in several countries and is important to human health, animal health, and agriculture. We report for the first time the presence of B. similaris in Córdoba Province, Argentina, extending the southern distribution of the species in this country and in South America. Anatomical, conchological, and molecular information obtained here represent the second contribution for this species in Argentina“.

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This paper presents integrative data about this species, with a list of GenBank records for  sequences from Argentina and have traced the transport of ornamental plants or organic compost within the country as the most probable source of the dispersal of this species.

Reference:
Serniotti, E.N. et al., 2020. New record and range extension of Bradybaena similaris (Férussac, 1822) (Gastropoda, Camaenidae) in Argentina. – CheckList 16(1): 211-217.

New streptaxid from Brazil

Salvador & Cunha just published a new paper, describing a new Brazilian species. “A new species of Streptartemon Kobelt, 1905 land snail from Santos, SE Brazil, is herein described as Streptartemon waukeen sp. nov., from specimens originally found in an urban garden. The new species is distributed along coastal urban areas from southern Espírito Santo state to São Paulo state. It can be diagnosed from its congeners by the following features: a comparatively small shell; the penultimate and body whorls bulging and rounded; a small and roughly circular aperture; and the lack of apertural lamellae/teeth. The new species also presents a bursa tract diverticulum, which is a plesiomorphic state in stylommatophoran snails, but absent in most streptaxid genera. Further details of the genital anatomy, as well as DNA barcoding information, are provided“.

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The discovery of this new taxon in urban areas is remarkable. Further collecting should show if this species is confined to anthropological habitats or not.

Reference:
Salvador, R.B. & Cunha, C.M., 2020. A new species of Streptartemon from southeastern Brazil (Gastropoda: Streptaxidae). – Journal of Conchology 43(5): 513-520.

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.

New Pantepui Plekocheilus

Freshly pressed: a paper with additional data on snails from the Eastern Pantepui region, with description of 3 new species. “Recent visits by a herpetologist to hitherto unexplored or ill–explored tepuis in the Pantepui area of Venezuela reveal three new species: Plekocheilus (P.) sanderi, P. (Eurytus) annetae, and P. (E.) timoi. This brings the total number of recognised species in the Pantepui to 27 land snails, of which 23 belong to the dominating superfamily Orthalicoidea“.

sanderi-annetae-timoi

 

Reference:
Breure, A.S.H., 2020. Additional data on Eastern Pantepui Orthalicoidea land snails (Mollusca, Gastropoda). – Journal of Conchology 43(5): 481-496.

New Argentinian Succinea

Recently Miquel et al. investigated the Succineidae from the southern tip of South America and found a new species.

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A new species of Succinea from Santa Cruz Province (Argentina) is described. Succinea argentina sp. nov. is characterized by the following features: a shell of regular growth, 3 to 3.25 whorls, length of 6.0 to 7.15 mm, shell not succineid, opaque walls and conspicuous axial ribs; straw­yellow opaque deciduous peri­ostracum; radular formula: 21-9-C-9-21, with central tooth tricuspid, lateral teeth bicuspid and marginal teeth tricuspid; penis with epiphallus, wrapped in a com­mon sheath, without appendices, and formed by two regions: a long proximal re­gion, which is lined by a mucosa with multiple transverse folds, and a short distal region, which opens into the atrium; vas deferens composed of three main regions – pre­prostatic, prostatic and post­prostatic –, entering the epiphallus subtermi­nally, and covered by a mucosa with multiple folds of different sizes; vagina long, thin and convolute; spermatheca globose, with a long duct that opens in the last portion of the vagina; atrium short“.

As with all succineid species the anatomy plays an important role. Nonetheless it is remarkable that the authors diagnose this species morphology as “not succineid”. There are several other related species occurring in this region from which it is, however, clearly different.

Reference:
Miquel, S.E. et al., 2019. A new species of Succinea Draparnaud from the extreme south of Argentina. – Spixiana, 42: 177-184.

Veronicellids recharacterised

Just published: a paper by Rocha & D’ávila on the Veronicellid genera Latipes and Angustipes.

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Their abstract is “The genera Angustipes Colosi, 1922 and Latipes Colosi, 1922 were originally proposed as “groups” within the genus Vaginulus Ferrussac, 1822, and since their establishment they have been variously considered valid or invalid until they gained the ultimate status of genus. The descriptions of both genera are general and broadly inclusive, and this fact has complicated taxonomic recognition. Additionally, incomplete descriptions and difficult identification of characteristics in the name-bearing type specimens demonstrate the need to revisit the species and revise the two genera. Herein, we broaden the description of Latipes erinaceus Colosi, 1922 with respect to the circulatory system, the radula, the jaw, the position of entry of the ligation duct in the bursa copulatrix in relation to the canal of the bursa, the origin of the muscle of the penial gland, along with the morphometric characteristics of the phallus, the penial gland, the pedal gland, and the bursa copulatrix. We also propose new differential diagnoses for the genera Angustipes and Latipes, limited to the essential characteristics that enable taxonomic recognition. Hence, we propose the assignment of the species L. erinaceus, Latipes rosilus (Thiele, 1927), Latipes ribeirensis (Thiele, 1927), and Latipes absumptus (Colosi, 1921) to the genus Angustipes, based on the presence of morpho- logical characteristics attributable to this genus, such as the phallus being short and conical; the bursa copulatrix being sessile or short, and lacking a head; the ligation duct inserted near the canal of the bursa; as well as on the similarity in phallus morphology with Angustipes difficilis Colosi, 1922, the type species of this genus“.

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The family Veronicellidae is notoriously enigmatic due to the need to use anatomical charcters for classification. This paper is thus a welcome addition to the literature of this family.
Reference:
Rocha, C.A. & D’ávila, S., 2019. New Morphological Characterization of Latipes erinaceus (Gastropoda, Veronicellidae), Differential Diagnosis for the Genera Angustipes and Latipes, and Novel Combinations for Species of Latipes. – Zoological Science (Tokyo), 36 (3):231-241.

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.

New Humboldtiana species

Recently a paper was published by Mejía et al., on species from northern Mexico. “Three new species of the genus Humboldtiana are described. The presence of a mantle mottled with dark spots allocates H. paquimei from Chihuahua to the subgenus Gymnopallax. On the other hand, the embryonic whorls, a smooth and granular sculpture distributed over the shell surface, allocate H. wixarika from Jalisco and H. aurea from Chihuahua to the subgenus Humboldtiana s.s. The newly described species are distinguished from other species of the genus by the combination of shell and anatomical characters and by their geographic distribution”.

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The paper is dedicated to the memory of the late Dr Fred G. Thompson, a specialist of Mexican and Central American non-marine molluscs.

Reference:
Mejía, O. et al., 2018. Three new species of Humboldtiana (Gastropoda, Pulmonata: Humboldtianidae) from Mexico. – The Nautilus 132 (2): 124-130.

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.