Tag Archives: taxonomy

New Brazilian species

Recently published, Simone & Do Amaral studied snails collected on islands off the Brazilian coast and discovered new species.

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Their abstracts is as follows: “Three new species of Bulimulidae (Gastropoda, Pulmonata) are described, each one endemic to a different island off the São Paulo coast, showing a high degree of endemicity of these islands in terrestrial malacofauna. Drymaeus castilhensis occurs on Castilho Island, it is mainly characterised by the strong axial dark spots in the shell or in being totally pale beige, penis elongated, lacking any inner chambers or glands, and double ducts of albumen gland. Drymaeus micropyrus occurs on Queimada Pequena Island, it is mainly characterised by greenish-cream shell, with narrow axial spots, and single duct of albumen gland. Bulimulus sula is from Alcatrazes Island, its main features include a relatively cylindrical, featureless shell, bilobed penis and, mainly and remarkably, a genital appendix that looks like a small accessory penis. These three species are described and compared with similar species, and accounts on their biogeography”.

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The two species of Drymaeus, if presented as shells only and without locality data, are so similar that would have doubted them to be two different taxa. But the anatomical differences evidently show that cannot be conspecific. Also the Bulimulus species is anatomically peculiar with the reported “small accessory penis”.

Reference:
Simone, L.R.L. & Amaral, V.S. do, 2018. Insular life: new endemic species from São Paulo oceanic islands, Brazil (Pulmonata, Bulimulidae), as example of endemicity. – Journal of Conchology, 43(2): 167-187.

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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

New Cuban Cerion

In a not so current journal, a new species of Cerion was just described from Cuba.

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Cerion milerae sp. nov. is described from the type locality Punta Bejuquera, Gibara, Holguín province, Cuba. It is compared conchologicaly with Cerion paucicostatum paucicostatumCerion paucicostatum harringtoni and Cerion caroli aedilii. Anatomically it is compared with Cerion paucicostatum paucicostatum. With its description the number of species known from Cuba is increased to 148 and to 35 the number of species and subspecies known from Holguín province. An extensive survey in the zone showed that Cerion milerae sp. nov. is microlocalized, associated to Bayhops (Ipomoea pes-caprae), in sandy substrate”.

Reference
Suárez, A., 2018. Especie nueva de Cerion (Mollusca: Pulmonata: Cerionidae) de Holguín, Cuba. – Novitates Caribaea, 12: 43-48.

Xolotrema and the collation of Ferussac’s ‘Histoire naturelle…’

Harry Lee regularly adds insightful tidbits which go way beyond the limited distribution of the home-made journal in which he publish them. One such tidbit is the correct publication date of a Polygyrid snail occurring in Florida and described by Férussac. While has has struggled to get everything right, he now presents an updated collation of Férussac’s Histoire naturelle…, which deserves a wider audience. Reason why I copy his whole article here in this blogpost.

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Reference:
Lee, H.S., 2018. Xolotrema denotatum (Férussac, 18xx), its iconography and taxonomy – resolution. – Shell-O-Gram, 59 (4):2-4.

Taxonomy of Omalonyx

A group of Brazilian authors have made a comprehensive study on the succineid genus Omalonyx, with interesting results.

“The genus Omalonyx d’Orbigny, 1837, includes neotropical semi‐aquatic succineid slugs and comprises six recognized species to date. Field surveys across continental South America recovered five of the six recognized species. According to the morphological characters traditionally included in Omalonyx descriptions, the specimens were tentatively identified as O. matheroni, O. pattersonae, O. convexus, O. geayi and O. unguis. Employing sequences of mitochondrial cytochrome oxidase I (COI) alone or combined with the nuclear second internal transcribed spacer (ITS2) in discovery methods of species delimitation (GMYC and STACEY) led to species delimitation hypotheses that, except for unambiguously supporting O. convexus, have no correspondence to morphologically based assignments. To choose the delimitation model that best fit our data, the hypotheses recovered by GMYC, STACEY and morphology and created by merging species recovered by those methods had their marginal likelihood estimated and compared using the Bayes factors. The best‐supported hypothesis distinguished two species besides O. convexus: one widespread over most of South America and the other restricted to Rio de Janeiro State, Brazil. Furthermore, the pattern of genetic structuring supports pathways connecting the Amazonian and Atlantic forests. This pattern is similar to that observed in terrestrial taxa (e.g., forest‐dwelling small mammals) and is different from the pattern for fully aquatic taxa.”

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This is a well-executed study that uses different methods to formulate several hypotheses. The best-supported one leads the authors to conclude that there are two species to be recognised: O. convexus (Martens, 1868) and O. matheroni (Potiez & Michaud, 1835). This result is interesting, the more since this group is extremely difficult to study using the morphology alone. Such integrative studies are thus the way forward, and should be attempted also for other groups of Neotropical snails.

 

Reference:
Vidigal, T.H.D.A. et al., 2018. Integrative taxonomy of the neotropical genus Omalonyx (Elasmognatha: Succineidae). – Zoologica Scripta, 47 (2): 174-186.

New Urocoptid from Hispaniola

Just released: a paper by Thomas Watters dealing with the urocoptid genus Gyraxis, and describing a new species. The abstract reads “The genus Gyraxis in Hispaniola is reviewed, currently only known from the area of the Bahía de Samaná in the Dominican Republic. It includes three taxa: Gyraxis samana (Clench, 1966), G. sericata (Pilsbry, 1903) and G. excalibur new species. The radular morphology and isolation from Cuban Gyraxis suggest they may yet require a new genus”.

Watters also, when dealing with the nomen inquirendum Cylindrella gouldiana Pfeiffer, 1853, indicated this taxon has never been figured and that Crosse subsequently mentioned the first precise locality for the species (“Région Dominicaine: rochers du Tablaso, près San Cristobal (A. Sallé)”). Watters expressed “it is not clear how he knew this”. This answer is simple: Crosse always indicated behind his localities the collector of the material, in this case Sallé. The material which Crosse saw may either have been returned to Sallé or have ended up in the Crosse collection. Both collections have been dispersed after their owner’s death, and the current depository of the material is unknown.

Reference:
Watters, G.T., 2018. The genus Gyraxis Pilsbry, 1903 (Gastropoda: Urocoptidae) from Bahía de Samaná area of the Dominican Republic. – Journal of Conchology, 43: 103-108.

 

Ovachlamys fulgens redescribed

Salles et al. just published a paper on the tropical Helicarionid snail Ovachlamys fulgens (Gude, 1900) for which they used Brazilian material to redescribe the species.

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Their abstract reads “The geographical distribution of the jumping snail Ovachlamys fulgens Gude, 1900, originally described from Loo-Choo Island, is expanding rapidly throughout the tropics. The full extent of the environmental damage caused by the in- troduction of this exotic species is still unknown. So far, it has been implicated in damage to orchids and horticultural plants. Ovachlamys fulgens is only known by a few characteristics of the shell and information on its anatomy is scant. The present study aims to redescribe this species based on specimens from Brazil, which is here characterized by the a globose shell, with wide aperture, externally micro-sculptured with undulating spiral groves, umbilicus partially obliterated by a thin plate, pedal sole tripartite, cephalopedal mass consisting of a series of oblique muscles, mantle with two flattened lobes, large caudal horn, pallial cavity small, vascular system evident, auricle fibrous, ventricle highly muscular, aorta subdivided in cephalic and gastric veins, a large kidney internally folded, jaw smooth and crescentic, radulae with 127 teeth per row (55-(8)- 1-(8)-55), each row with about 25 mm, crop absent, salivary glands fused, stomach large with thin walls, ovotestis with at least three distinct lobes, talon totally immersed in the albumen gland, uterus with two regions, capsule gland hardly visible, bursa copulatrix small and sacculiform, penial sheath present, epiphallus small and narrow, nervous ring asymmetrical, visceral ganglion on left side only, five and six nerves running from each cerebral and pedal ganglia, respectively, one statocyst immersed in each pedal ganglion, and two pairs of ganglia (mandibular and buccopharyngeal ganglia) extra to the nervous ring.”

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The authors have done a thorough morphological and anatomical study, which will undoubtedly help to identify this species in future.

Reference:
Salles, A.C.A., Oliveira, C.D.C. & Absalão, R.S., 2018. Redescription of the jumping snail Ovachlamys fulgens (Gude, 1900) (Gastropoda: Helicarionoidea: Helicarionidae): An anatomical and conchological approach. – The Nautilus, 132 (1): 19-29.