Tag Archives: mexico

Yucatan gastropods

A paper in the journal of the German shell collectors club by Gibb is about Mexican land snails from Yucatán and Quintana Roo.

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A two-week stay in the south-east of Mexico in the summer of 1999 was used to collect marine mollusks as well as land and freshwater gastropods. All of the localities were in the states of Quintana Roo and Yucatán. The non-marine material resulted in 28 species (4 freshwater and 24 terrestrial species) all by collecting empty shells. Various soil samples were also taken and later examined under the binocular“.

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Gibb, W., 2020. Nicht-maritime Gastropoden von der Halbinsel Yucatan (Mexiko). – Club Conchylia Mitteilungen 34: 17-28.


Land cover change in NE Mexico

Land-cover change and protected nature areas is not a subject that is well-studied. Vázquez-Reyes et al. recently published about it related to a region in northeastern Mexico.

Protected areas (PAs), priority terrestrial regions (PTRs) and priority terrestrial sites (PTSs) are strategies for conserving natural resources. However, loss of coverage on the peripheries can lead to isolation between these conservation areas. The present study analyzed the association of the change of coverage inside and outside 2 PAs, 5 PTRs and 128 PTSs in Tamaulipas with the richness and geographic distribution of 5 species groups (strict, semi-aquatic and tolerant hydrophiles, as well as gastropods and pteridophytes in 3 periods (1986, 2002 and 2011). In addition, we identified areas with similar species composition and socioeconomic-environmental factors related to the change in coverage. The highest richness and geographic distribution of aquatic plants occurred outside the conservation areas, while the greatest richness of ferns and gastropods was present inside them. The greatest loss of coverage occurred outside the El Cielo Biosphere Reserve and the Sierra de Tamaulipas PA. The loss of native cover increased in the last 30 years and is greater outside the conservation areas, therefore is necessary to propose and implement strategies to reduce the isolation of these areas“.

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Although no list is given of the gastropods studied, assumingly they were terrestrial species. This is a policy study rather than a taxonomical one, but for conservation purposes it may be of interest.

Vázquez-Reyes, C.J. et al., 2019. Biodiversity risk from land-cover change in terrestrial priority regions and protected natural areas in northeastern Mexico. – Revista Mexicana de Biodiversidad 90: e902726 (16 pp.).

Cornu aspersum as pest

A brief paper by Ruiz-Galván et al. (2918) described how in Mexico a non-native population of Cornu aspersum (O.F. Müller, 1774) developed since 2013 into a pest on apple trees. Although the authors have not found a specific reason for this, their paper shows an effective counter-tactic.

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Ruiz-Galván, I. et al., 2018. Helix aspersa (Stylommatophora: Helicidae) plaga emergente de la manzana (Malus spp.) en Guerrero, Chihuahua. – Acta Zoológica Mexicana (n.s.) 34: e3412161 (5 pp.).

New record for Gulella bicolor in Mexico

A specimen of Huttonella bicolor = Gulella bicolor (Hutton, 1834) was collected from clayey-sandy soil in Tabasco, Mexico, which constitutes its second record in the state and the third in Mexico. This small gastropod is a predator that has mainly spread through tropical and island regions as an exotic species. Its introduction to Asian and Caribbean Islands is noteworthy. Its pupiform shell and the lamella or tooth complex were compared against previous descriptions. In Mexico, this species has been found in northern Veracruz and Tabasco, which confirms that it is spreading along the Gulf of Mexico from the United States towards Brazil. The features of this streptaxid as a potential hazard through its preferred prey are discussed”.

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An additional record to the ones given in the paper is the recent mentioning of this species for Belize by Dourson et al. (2018: 315).

Introduced species are often problematic with regard to the native malacofauna, but in this case the authors argue that also additional reasons may be present for keeping a close eye on the further spread of this species. Which is related to exotic species always a good idea to follow and document their distribution.

Costillo-Rodriguez, Z.G. et al., 2018. A new record of Huttonella bicolor (Hutton, 1834) (Mollusca, Gastropoda, Streptaxidae) in Mexico. – Acta Zoológica Mexicana (n.s.) 34: e3411181 (6 pp.).

New Bunnya species from Mexico

Mexican papers are plentiful this moment, but I am sure it is coincidental…

Just published, a paper by a mixed Mexican-Costa Rican author team, whose abstract reads as follows: “We describe a new helicoidean semi-slug based on morphological and molecular evidence. The new species belongs to the genus Bunnya and is described from a small agricultural area in Zinacantepec, San Juan de las Huertas, México. The genus Bunnya is externally similar to Xanthonyx, another Helicoidea genus; both genera have similar shell and body form, and both have a tail horn. Internally, Bunnya is similar to Humboldtiana, since both have dart-sacs (3 in Bunnya, 3−4 in Humboldtiana) surrounding the vagina, two dart-bulbs associated with each dart sac, and a gland number similar to the dart-sacs number. Four adult specimens of Bunnya metli n. sp. were dissected and compared with the two described species: B. bernardinae from Cuajimalpa, México City, and B. naranjoe from Sierra de Manantlan, Jalisco. Bunnya metli n. sp. is characterized by: very closely-spaced radial riblets (about 23 per mm) crossed by fine spiral wavy threads on the embryonic whorls; unfused glands inserted on the vagina above the dart-sacs and only one dart per sac; a short, swollen penis with a large spherical verge about half the penis size; an elongated bursa copulatrix with a slight constriction in the middle; a long bursa copulatrix duct; and dart sacs with a muscular pad within the vaginal lumen, surrounding the basal part of the genitalia. We performed a phylogenetic analyses using data from fragments of 16S rRNA mtDNA and 28S rRNA genes from one of the collected specimens, as well as other helicoidean sequences from GenBank. Our analyses support the membership of Bunnya metli n. sp. in Xanthonychidae. This suggests that the taxonomic position of Bunnya in Humboldtianidae or Xanthonychidae warrants reevaluation”.

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This appears to be a very well-executed study on this novelty, which also question the familiar placement of the species. No other Bunnya species have been sequenced, while only two taxa of the Xanthonychidae are currently included in GenBank. Further research may solve this situation.

Araiza-Gómez, V. et al., 2019. A new species of the genus Bunnya H.B. Baker, 1942 (Helicoidea) from Mexico. – Malacologia, 62 (2): 237-246.

Auguste Ghiesbreght’s travels in Mexico

Through serendipity I found an interesting paper on Auguste Ghiesbreght and his collecting work in Mexico (Schätti et al., 2018). Ghiesbreght (1812-1893) was a Belgian botanist, who lived for several decades in Mexico and collected plants, animals and other natural history objects, which were shipped to Europe for identification. His malacological material was used e.g. by Nyst, L. Pfeiffer and Crosse and P. Fischer.

Although the paper focusses on frogs, snakes and lizards, the content is interesting as the land snails were in all likelihood collected by Ghiesbreght during the same trip. He sent end 1841 a shipment which contained among others “sixty-two terrestrial snails (24 spp.)”.

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Despite some biographical data having been published previously, a correct itinerary of his travels through Mexico has never been detailed and as such this paper fills a gap which may help to locate the occurrences of some species.

Schätti, B., Ineich, I & Kucharzewski, C., 2018. Auguste Ghiesbreght’s natural history exploration in Oaxaca and other parts of Mexico until 1854. – Acta Zoológica Mexicana (n.s.) 34: e3411184 (22 pp.).

More on Humboltiana

Another paper on Humboldtiana appeared as an advance online paper; it is by López, Zúñiga & Mejía. Their abstract is “It has been postulated that Pleistocene climatic change has promoted repeated contraction and expansion of the distributions of montane taxa in Mexico (‘see-saw effect’). Under such a scenario, we would expect taxa, particularly those with limited dispersal such as land snails, to exhibit strong phylogeographic struc- ture. Using an approach based on four molecular markers (COI, 16S, ITS1 and ITS2), we investigated the phylogeography of Humboldtiana durangoensis, a land snail endemic to the Madrean central region of the Sierra Madre Occidental of Western Mexico. We sampled a total of 178 individuals from 16 localities spanning the known geographic range of the taxon. Two main groups of H. durangoensis were recovered, one occupying the northern part of the current range of the species and the other the southern part. While these two groups show high haplotypic diversity and low nucleotidic diversity, suggesting a recent demographic expansion, our Bayesian Skyline Plots point to a more complex demographic history, involving expansion and contraction of the effective population size. The phylogeographic structure of H. durangoensis in the Sierra Madre Occidental may possibly be a result of Pleistocene climatic changes”.

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As postulated before in literature, land snails are good model organisms for this kind of phylogeographical studies. It is noteworthy that this group of Mexican researchers have begun to study this group of land snails as shown by this recent post.

López, B. et al., 2019. Phylogeographic structure in the apparent absence of barriers: a case study of the Mexican land snail Humboldtiana durangoensis (Pulmonata: Humboldtianidae). – Journal of Molluscan Studies : (9 pp.) [advance online] doi:10.1093/mollus/eyz007

Fossils from NE Mexico

Vega et al. just published a paper on fossils from northeastern Mexico. Their abstract reads as follows: “Additions are offered to the diverse estuarine, freshwater and terrestrial gastropod fauna of the Upper Cretaceous (Campanian) and Paleocene lithostratigraphic units of the Difunta Group, NE México (Coahuila and Nuevo León). Nineteen species of continental gastropods (five of them new) are reported and illustrated from the upper Campanian Cerro del Pueblo Formation (Las Águilas/Porvenir de Jalpa locality) and the Paleocene Las Encinas Formation (La Leona locality), northern Parras Basin, Difunta Group, Coahuila. The first record of pulmonate gastropods from the Difunta Group is based on several specimens of different species. This is the third contribution dealing with these continental gastropods from the study region and a revised list of reported species is presented. Although we follow the most recent classification of continental gastropods, we also base the identification on paleonto- logical systematics, knowing that some important diagnostic features were not preserved. Thus, we do not intend to propose paleobiogeographic or evolutionary inferences. Our main goal is to present the paleodiversity known from the study area, in hope that these data would be useful for more detailed studies in the near future”.

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The new species are Goniobasis unilirata, Pleurocera gigantica, Birgella burchi, Haitia taylori, and Holospira thompsoni. All new taxa are authored by Naranjo-García & Aguillón.

Vega, F.J. et al., 2019. Additions to continental gastropods from the Upper Cretaceous and  Paleocene of NE Mexico. – Boletin de la Sociedad Geologica Mexicana, 71 (1):169-191.

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.

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

Holospira in Oaxaca

Guerrero-Arenas et al. (2018) published about their findings of a Holospira species in Oaxaca state, Mexico. Their abstract reads: “Holospira (Bostrichocentrum) goldmani Bartsch, 1906 is an urocoptid gastropod distributed throughout northwestern Oaxaca in southern Mexico. Since its original description, posterior records have been restricted to the Mixteca Baja region of Oaxaca. The purpose of this paper is to expand on the geographical distribution of this species, georeferencing six additional localities. Five of our sites are located in the Mixteca Alta region of Oaxaca. Holospira goldmani can survive in soil derived from non-calcareous rocks. Field observations of ecological preferences of H. goldmani suggest that they are more ecologically tolerant than previously thought”.

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The pictures of the localities where these snails were found show the volcanic rocks and several pine forest demonstrating that this species is indeed ecologically tolerant and may be found in habitats where snails usually are not very abundant.

Guerrero-Arenas, R. et al., 2018. New occurrences of Holospira (Bostrichocentrum) goldmani Bartsch, 1906 (Gastropoda, Urocoptidae) in northwestern Oaxaca, southern Mexico. – CheckList, 14 (1): 107-112.