Tag Archives: argentina

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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Priority conservation areas

A few years ago a species catalogue was published for Argentina (Superfamily Orthaicoidea only), which now forms the basis for a paper on conservation by Ovando et al.

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Their abstract reads “Mollusca is a megadiverse phylum with an estimated number of 70,000–76,000 described species which can inhabit a wide variety of environments. Among them, land snails are a main component of terrestrial ecosystems and they play a pivotal role in ecosystem functioning. They are suffering habitat loss, overexploitation and competition from introduced species, but are regarded as a “non-charismatic” group for conservation purposes. Orthalicoidea is a dominant faunal element in the Neotropics and in Argentina includes 104 species that inhabit a variety of environments. Their abundance, diversity, comprehensive taxonomy and widespread representation in different ecoregions makes this molluscan group an excellent model for biodiversity assessments. The database used here consisted of 985 unique geographic records of 104 species. Species distribution models were generated using the Maximum Entropy method and Zonation v 3.1 was used to evaluate the proposed conservation goals. Three analyses including species distributions, the current protected areas system (PAs) and the Human print layer were carried out. This allowed the identification of priority areas for conservation, the percentage of the species distribution under PAs and analysis of the potential impacts under current land use and in the priority areas detected above. Sixty-one species were modeled, and 59 of them were included in the priority area selection process due to their high area under curve (AUC) scores. Five high priority areas located in the different ecoregions, were identified: 1-dry Chaco, 2-humid Pampas, 3-Southern Andean Yungas, 4-Alto Paraná Atlantic Forests and 5-high Monte. A small percentage of the average distribution range of Orthalicoidean species (3%) was within the current protected areas. Highest-ranked priority areas for land snails are outside the current protected areas system. When human impact is considered, the priority areas are reduced in size and appear as small patches. However, highest priority areas for conservation continue being those detected in the above analyses. Most of the areas detected are used for economic purposes, creating conflicts of interest between the development of human activities and conservation. This study represents one of the first attempts to identify ecoregion level priority areas for a terrestrial invertebrate group. Further analyses, including new predictors and other molluscan taxa, would improve planning the conservation of poorly known invertebrate groups“.

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A useful study, the more as the authors have embraced the ecosystems approach widely used in conservation policies, and with interesting results concerning this group. Their conclusions that conflicts of interests between economic development and conservation continue is nor new nor re-assuring. We all know that conservation is likely to draw the shortest straw in this battle…

Reference:
Ovando, X.M.C. et al., 2019. Identifying priority areas for invertebrate conservation using land snails as models> Journal for Nature Conservation 50: 125707 (10 pp.).

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 fossils from Argentina

Just published: a paper by Miquel on continental gastropods from Argentina. “A new genus and two new fossil species of continental gastropods from the upper part of the Irene Formation—which is probably Huayquerian–Montehermosian (early Pliocene) and is exposed in the Quequén Salado River (Buenos Aires Province, Argentina)—are described: the new genus and species of freshwater gastropod Argentisioliella pardignasi (Cochliopidae) and a new species of landsnail of the family Bulimulidae (Bocourtia (Kuschelenia?) bonariensis). Argentisioliella pardignasi is morphologically related to those described for the Pebas Formation of Pliocene age. The specimens have bulloid morphology, long and narrow aperture, with a channeled peristome and two folds in the columellar wall. This is the first description of similar snails of the Pebas and Irene formations. Bocourtia (Kuschelenia?) bonariensis is the most ancient record for the genus, being recorded far away from the area of its current distribution (northwest Argentina). The specimen is an internal cast, with more than three convex whorls and a large aperture. Its distribution would coincide with the final phase of the Mio–Pliocene climatic change, when numerous terrestrial gastropods of Patagonian and Pampean provenance disappeared. A well-conserved specimen of the terrestrial snail Austroborus (Strophocheilidae Pilsbry), showing an almost complete shell, with more than 4.5 convex whorls, last whorl and large aperture, was also recorded. In the study area, this genus was present during the Pleistocene and Holocene, living in restricted areas of Argentina and Uruguay, with a disjunctive and relictual distribution“.

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Always interesting to see how palaeontologists are able to read those fragments. In this case the connection between Central Argentina and Pebas, in northeastern Peru on the Amazonian side, is remarkable. Thus a short but interesting paper.

Reference:
Miquel, S.E., 2019. A new genus and two new species of fossil continental gastropods from the early Pliocene of Argentina (Mollusca). – Ameghiniana 56 (2): 187–194.

Historical range information

A paper just published by Salvador provides interesting information on some distribution ranges based on a historical collection. The abstract reads “The malacological collection of the Museum of New Zealand Te Papa Tongarewa (NMNZ), despite naturally focusing on New Zealand species, also includes a variety of specimens from South America. Examination of this material revealed new distributional data for several species. All Brazilian, Uruguayan and Argentinian terrestrial gastropods from the NMNZ collection were examined and re-identified (no material from Paraguay was found). The information gathered was compiled and is presented in this article, and may contain significant data for malacologists working with the region’s fauna. In summary, 99 species are reported, 13 of which represent new records and meaningful increments in geographical distribution, either extending their known range or filling distributional gaps. Moreover, the NMNZ collection houses the type material of six species from Brazil and Argentina described by the New Zealand malacologist Henry Suter (1841–1918) in 1900“.

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The material consists of species from 17 families. “The following 13 species have significant increments in their distribution (range extension or filling of distributional ‘gaps’): Auris chrysostoma, Auris illheocola, Auris melanostoma and Thaumastus nehringi (Bulimulidae [Thaumastus belongs to the Megaspiridae]); Callionepion iheringi (Megaspiridae); Cyclodontina fusiformis, Moricandia willi and Spixia martensii (Odontostomidae); Simpulopsis decussata (Simpulopsidae); Neobeliscus calcarius (Achatinidae); Happia iheringi (Scolodontidae); Epiphragmophora hieronymi (Epiphragmophoridae); and Solaropsis punctatus (Pleurodontidae) [sic, Solaropsidae]“. The author rightly draws attention to the fact that even historical collections – although sometimes lacking from precise data – can contribute to our knowledge of distribution of species. This being said, however, it also points to the insufficient inventories being made on a detailed scale in many of the Neotropical countries which leads to insufficient insights in the distribution of many species.

Reference:
Salvador, R.B., 2019. Brazilian, Uruguayan and Argentinian terrestrial gastropods in the collection of the Museum of New Zealand Te Papa Tongarewa. – Tuhinga, 30: 82-98.

Clessinia from Argentina

A recent paper by Cuezzo et al. provides a revision of Argentinian species. Their abstract reads in full:

“Background: Land gastropods of the Dry Chaco merit special attention because they comprise a highly diverse but barely studied group. Clessinia Doering, 1875 are typical inhabitants of this ecoregion. The inclusion of their distribution areas into Spixia range, their shell shape similarities, and a former molecular study raised doubts on the monophyly of this genus. The present study review the species of Clessinia, under a morphological, geometric morphometrics, and molecular combined approach.
Methods: Adults were collected, photographed, measured, and dissected for anatomical studies. Shell ultrastructure was studied with scanning electron microscope. Geometric morphometric analyses on shells were performed testing if they gave complementary information to anatomy. Two mitochondrial genes, and a nuclear region were studied. Phylogenetic reconstructions to explore the relationships of DNA sequences here obtained to those of Clessinia and Spixia species from GenBank were performed.
Results: Species description on shell, periostracal ornamentation and anatomy is provided. We raised former Clessinia cordovana striata to species rank, naming it as Clessinia tulumbensis sp. nov. The periostracum, consisting of hairs and lamellae, has taxonomic importance for species identification. Shell morphometric analyses, inner sculpture of penis and proportion of the epiphallus and penis, were useful tools to species identification. Nuclear markers do not exhibit enough genetic variation to determine species relationships. Based on the mitochondrial markers, genetic distances among Clessinia species were greater than 10%, and while C. cordovana, C. nattkemperi, and C. pagoda were recognized as distinct evolutionary genetic species, the distinction between C. stelzneri and C. tulumbensis sp. nov. was not evident. Clessinia and Spixia were paraphyletic in the molecular phylogenetic analyses. Species of Clessinia here treated have narrow distributional areas and are endemic to the Chaco Serrano subecoregion, restricted to small patches within the Dry Chaco. Clessinia and Spixia are synonymous, and the valid name of the taxon should be Clessinia Doering, 1875 which has priority over Spixia Pilsbry & Vanatta, 1894.
Discussion: Our results support the composition of C. cordovana complex by three species, C. cordovana, C. stelzneri, and C. tulumbensis sp. nov. The low genetic divergence between C. stelzneri and C. tulumbensis sp. nov. suggests that they have evolved relatively recently. The former Spixia and Clessinia are externally distinguished because Clessinia has a detached aperture from the body whorl forming a cornet, periostracal microsculpture extended over dorsal portion of the peristome, five inner teeth on the shell aperture instead of three–four found in Spixia. Morphological similarities exists between both genera in shell shape, type of periostracum microsculpture, reproductive anatomy, besides the overlap in geographic ranges”.

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This is an interesting paper for me, as more than 6 years ago I did research on type material in the London museum and found the species of the two ‘genera’ difficult to entangle, the more when phylogenetic results proved a paraphyletic relationship (Breure & Romero, 2012). This study comes to the same phylogenetic outcome as shown in the figure below. And for clarity: the Clessinia specimens used in our 2012 study were identified and supplied to us by one of the current authors and another Argentinian malacologist; they had more expertise and resources available.

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The conclusion of the study by Cuezzo et al. is that Clessinia and Spixia are synonyms, with the older name (Clessinia) taking precedence. As such this is correct, but at the same time they conclude that the two ‘genera’ are morphological distinguishable (see the Discussion in their abstract). As taxonomists we have a solution for this: the subgenus…, which is treated in MolluscaBase as ‘alternate representation’. So instead of complete synonymisation, I would say there seems enough reason to distinguish the two as subgenera despite not being strictly monophyletic. The nomenclature then becomes:

Clessinia Doering, 1875
Clessinia (Clessinia) Doering, 1875 – type species Bulimus (Clessinia) stelzneri Doering, 1875.
Clessinia (Spixia) Pilsbry & Vanatta, 1898 – type species Clausilia striata Spix in Wagner, 1827.
See Cowie et al. (2004) for details on the names of Spix and Wagner.

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In this paper also one new species is described. The authors say “The new species, Clessinia tulumbensis sp. nov. include Clessinia cordovana striata (Parodiz, 1939). The name striata has not been used here to avoid homonymy with Pupa striata Spix, 1827 [= Clausilia striata Spix in Wagner, 1827], the type species of Spixia, since in the present study the genera Clessinia and Spixia are proposed as synonymous. The new species with its own holotype and paratypes is defined based on live-collected material from which DNA sequences were obtained and the anatomy described. In this sense, although the Parodiz name is preoccupied, we are not replacing the name proposed by him in 1939 but creating a new species with its own type series”.

With Parodiz’ name mentioned by the authors as a full synonym, I fail to see the reason to introduce the name tulumbensis as a species novum. Although it is correct to replace the name of Parodiz to avoid homonymy, it is nonsense to say that you can introduce a replacement name with its own type series. The name tulumbensis is thus not a ‘sp.nov.’ but a nomen novum. And the holotype of Clessinia cordovana striata Parodiz, 1939 (MACN-In 9127) becomes automatically the holotype of Clessinia tulumbensis! The “holotype IBN 883” and the paratype material mentioned in this paper has no status other than being vouchers for this study.

References:
Breure, A.S.H. & Romero, P.D., 2012. Support and surprises: a new molecular phylogeny of the land snail superfamily Orthalicoidea (Gastropoda, Stylommatophora) using a multi-locus gene analysis. – Archiv für Molluskenkunde, 141: 1–20.
Cowie, R.H. et al., 2004. The South American Mollusca of Johann Baptist Ritter von Spix and their publication by Johann Andreas Wagner. – The Nautilus, 118: 71-87.
Cuezzo, M.G. et al., 2018. From morphology to molecules: a combined source approach to untangle the taxonomy of Clessinia (Gastropoda, Odontostomidae), endemic land snails from the Dry Chaco ecoregion. – PeerJ, 6: e5986 (54 pp.).

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.