Tag Archives: anatomy

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.

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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.

 

Omalonyx unguis in Argentina

Recently, Guzmán et al. reported on this species with the following abstract: “Omalonyx unguis (d’Orbigny, 1837) is a semi-slug inhabiting the Paraná river basin. This species belongs to Succineidae, a family comprising a few representatives in South America. In this work, we provide the first record for the species from Misiones Province, Argentina. Previous records available for Omalonyx in Misiones were identified to the genus level. We examined morphological characteristics of the reproductive system and used DNA sequences from cytochrome oxidase subunit I (COI) gene for species-specific identification. These new distributional data contribute to consolidate the knowledge of the molluscan fauna in northeastern Argentina”.

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In the paper also figures of the shell and the genitalia are presented. The authors were likely unknown of the revisionary work of Vidigal et al. (2018), who showed that the correct name of this species is Omalonyx matheroni (Potiez & Michaud, 1835).

Reference:
Guzmán, L.B. et al., 2018. First record of the semi-slug Omalonyx unguis (d’Orbigny, 1837) (Gastropoda, Succineidae) in the Misiones Province, Argentina. – CheckList 14 (5): 705-712.

Brazilian Solaropsis

A recent paper by Cuezzo et al. discusses the position of Solaropsis brasiliana (Deshayes, 1832) and its relatives. Their abstract reads: “A detailed anatomical revision on Solaropsis brasiliana (Deshayes 1832) has been carried out. New characters on shell, anatomy of soft parts, and a review of the genus distribution in South America, as well as clarification on S. brasiliana distributional area are provided in the present study. Solaropsis brasiliana is diagnosed by its globose, solid, and hirsute shell, with periphery obsoletely angular, bursa copulatrix with a thick, long diverticulum, a thick, long flagellum and a penis retractor muscle forked, with the vas deferens passing through it. This compiled information was used to test the phylogenetic position of S. brasiliana within South American Pleurodontidae through a cladistics analysis. In the phylogenetic hypothesis obtained, S. brasiliana is sister group of S. gibboni (Pfeiffer 1846) and the monophyly of thegenus Solaropsis Beck is also supported. Here, we sustain that the distribution of S. brasiliana is restricted to Brazil, inhabiting the States of Rio de Janeiro, Espírito Santo, Bahia and Minas Gerais”.

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This study, which carries a somewhat misleading title, deals *not* with the phylogenetics of this group in the sense of molecular studies. The authors have made a cladistic analysis using morphological characters, a method that has some support in a restricted group of authors and had better be indicated as such to avoid confusion with the more generally used terminology.

The authors have included in their dataset the monotypic genus Olympus, described from the Pantepui region on the Brazilian-Venezuelan border. They suggest there are but slight differences with Solaropsis undata (Lightfoot, 1786) in their anatomy, and therefore “the validity of Olympus as a separate genus from Solaropsis, should be carefully considered until more information is available”. I would suggest that molecular studies might be able to clear this issue.

Reference:
Cuezzo, M.G. et al., 2018. Solaropsis brasiliana, anatomy, range extension and its phylogenetic position within Pleurodontidae (Mollusca, Gastropoda, Stylommatophora). – Anais da Academia Brasileira de Ciencias, 90 (3): 2753-2765.

Ventania from Argentina

Pizá et al. just published a paper in which they redescribed the single Ventania species known from Argentina.

“Although the presence of apertural folds and lamellae is the most recognizable character of the Odontostomidae, some species lack them, mostly in Anctus Martens, 1860, Bahiensis Jousseaume, 1877 and Moricandia Pilsbry & Vanatta, 1898. Eudioptus avellanedae Doering, 1881 – a slender odontostomid species that lacks even the slightest trace of folds or lamellae in its shell aperture – was however transferred to Odontostomus by Pilsbry in 1902 on the basis of its building forward of the aperture-margins. It is currently placed in its own monotypic subgenus, Cyclodontina (Ventania) Parodiz, 1940, on the basis of about the same argument. In this paper we redescribe its shell morphology and, for the first time, describe the internal anatomy of the pallial complex and the reproductive and digestive systems. The presence of a spongy gland in the pallial complex; of a short penis sheath with no retractor muscle; of a bursa copulatrix duct longer than spermoviduct, and of an epiphallic gland strongly support the inclusion of this unusual species in Odontostomidae. The species is diagnosable by the sculpture of the protoconch, which is not smooth as previously described, but has waved axial ribs crossed by spiral lines in young specimens; the distinctive external and internal shape of the bursa copulatrix duct; the internal penis wall divided in three regions of different sculpture; the smooth inner wall of the vagina; the long and cylindrical epiphallus with a distal widening indicating the presence of an epiphallic gland, and the penis retractor muscle inserted in the distal end of a short flagellum. These characters support the validity of Ventania Parodiz, 1940, different from Cyclodontina Beck, 1837”.

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The first two authors are known to have published already a series of thorough papers on Odontotomidae of Argentina. This paper follows in this line and gives convincing arguments why Ventania should be considered a separate, monotypic genus.

Reference:
Pizá, J., Cazzaniga, N.J. & Ghezzi, N.S., 2018. Redescription of Ventania avellanedae (Stylommatophora: Odontostomidae), a land snail endemic to the Ventania Mountain System, Argentina. – Zoologia, 35: e17786 (11 pp.). DOI: 10.3897/zoologia.35.e17786