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.
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.).
“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”.
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.).
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”.
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.
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.)”.
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.).
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”.
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
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”.
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.
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”.
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.