Snails, rats and parasites

Souza et al. just published a parasitological study where land snails also play a role. Their abstract is as follows “The nematode Angiostrongylus cantonensis is the most common cause of neuroangiostrongyliasis (manifested as eosinophilic meningitis) in humans. Gastropod molluscs are used as intermediate hosts and rats of various species are definitive hosts of this parasite. In this study, we identified several environmental factors associated with the presence and abundance of terrestrial gastropods in an impoverished urban region in Brazil. We also found that body condition, age and presence of co-infection with other parasite species in urban Rattus norvegicus, as well as environmental factors were associated with the probability and intensity of A. cantonensis infection. The study area was also found to have a moderate prevalence of the nematode in rodents (33% of 168 individuals). Eight species of molluscs (577 individuals) were identified, four of which were positive for A. cantonensis. Our study indicates that the environmental conditions of poor urban areas (presence of running and standing water, sewage, humidity and accumulated rain and accumulation of construction materials) influenced both the distribution and abundance of terrestrial gastropods, as well as infected rats, contributing to the maintenance of the A. cantonensis transmission cycle in the area. Besides neuroangiostrongyliasis, the presence of these hosts may also contribute to susceptibility to other zoonoses.”

Four species of land snails were studied in this project: Achatina fulica, Bulimulus tenuissimus, Sarasinula marginata and Subulina octona. Bradybaena similaris, which was also studied, proved not to be infected.

Reference:
Souza, F.N. et al. 2021. Angiostrongylus cantonensis in urban populations of terrestrial gastropods and rats in an impoverished region of Brazil. – Parasitology (advance online): 1-9. https://doi.org/10.1017/ S0031182021000597

Puerto Rican land molluscs

Recently a book announcement appeared with the title ‘Caracoles terrestres de Puerto Rico’. An intruiging title, as the last elaborate paper on the land snails from this Caribbean island appeared already in 1948!

Inspection of the book left me with mixed feelings. Written by two authors seemingly well-acquainted with the malacofauna of the island, the target group for this book is clearly the interested layman. The 13 chapters are structured as follows: history of malacological research, general introduction to snails, geological context of the island, snails living on the soil, tree snails, snails living on rocks, freshwater and seaside snails, carnivorous snails, snails with reduced shells, slugs, exotic snails, distribution, and finally conservation aspects. The book ends with a one page epilogue.

Gaeotis flavolineata

Although the book has an attractive lay-out with a number of full-page photos like the above, I really wonder what the authors had in purpose. Laymen will get only a general impression of the island fauna, but the book is unsuitable to take into the field. Leafing through it at home, a person will find several species named but without any taxonomic framework. There is no index, no systematic treatment and no literature references. If a person is interested to identify a shell this book will not help him out. Nor provides it any stimulus to dig further in literature to deepen a person’s knowledge.

When the idea was to present a general introduction, as the title suggests, the book fails sadly. Especially when compared to a similar book by Dourson et al. on the land snails of Belize that also recently appeared. The foreword by the authors is dated 2012, the book itself 2019, but is only now being advertised. It suggests that it was problematic to get the book published and I can see why.

Puerto Rico has a rich malacofauna and an interesting one. An updated overview would be very welcome, but this book is disappointing in most aspects. A completely missed chance as far as I am concerned…

Reference:
Genaro, J.A. & Sanchez, A.J., 2019. Caracoles terrestres de Puerto Rico. – Editorial Cocuyo [Habana, Cuba], 199 + 4 pp. ISBN 978-1696-979139. Price € 39.00 net.

Plant nurseries and slugs

Gutierrez Gregoric et al. reported on “Land slugs in plant nurseries, a potential cause of dispersal in Argentina. Commercial plant nurseries may serve as causes of dispersal of land snails and slugs (native and non-native) through the trade of plants and the related transport of eggs and small individuals that may pass unnoticed. Studies on the possible role of plant nurseries as a potential cause of dispersal of slugs in South America are lacking. To explore the role of garden centers, we collected and identified slugs in 12 commercial nurseries in two cities in the province of Buenos Aires, Argentina. Eight species of slugs were found. Based on our findings we validate the existence of Deroceras laeve and Belocaulus angustipes for Argentina and confirm the existence of Ambigolimax valentianus, which was recently cited for Argentina. We recommend that plant nurseries be regularly monitored given that snail and slug species are accidentally spread through trade in plants.”

Plant nurseries are a well-known source of unintentional invasions, due to the commercial trade. Regularly monitoring is indeed a sensible recommendation, but possibly not all countires make that into a stringent habit.

Reference:
Gutierrez Gregoric, D.E. et al. 2020. Land slugs in plant nurseries, a potential cause of dispersal in Argentina. – Arxius de Miscellania Zoologica 18: 173-181.

Arion in Mexico

“Knowledge of invasive terrestrial gastropods species in Mexico, and their potential impacts, is practically unknown. We document in this study, the occurrence of the large invasive slug Arion vulgaris Moquin-Tandon, 1855 for the first time in Mexico and only the third time in North America. In addition, we also report Arion (Kobeltia) intermedius Normand, 1852 from seven localities demonstrating that the species is already well established in Mexico. To identify both species, a Maximum-Likelihood phylogenetic analysis was performed using partial sequences, alone or concatenated, of nicotinamide adenine dinucleotide dehydrogenase 1 (ND1) and cytochrome C oxidase 1 (COI) genes. In addition, we used the morphological characters reported in other studies of these species to confirm their taxonomic identity. The phylogenetic analysis performed with the concatenated ND1 and COI genes, showed that the Mexican sequences of A. vulgaris were grouped with the corresponding sequences of this species from Canada and European countries. In addition, attributes such as the shape and position of the ligula were useful to confirm the taxonomic identity of this species. On the other hand, the phylogenetic analysis using ND1 sequences alone clustered Mexican specimens of A. intermedius with sequences of this species from Spain and UK. Characters such as the body color pattern, prickles on the dorsum, as well as characters of the reproductive system of A. (K.) intermedius corroborated the taxonomic identity of Mexican specimens of this species”.

A well-done paper which not only confirms the identity of the species by molecular research, but also provides anatomical illustrations of the differences. It is of course inevitable that a laboratory is needed, but once done such studies provide evidence needed for identifications. The paper is open access.

Reference:
Araiza-Gomez, V. et al. 2021.  Occurrence in Mexico of two European invasive slug species: Arion vulgaris Moquin-Tandon, 1855 and Anion intermedius (Norman, 1852). – BioInvasions Records 10 (1):10-20. https://doi.org/10.3391/bir.2021.10.1.02

New records from eastern Cuba

Two papers in the latest Festivus contain new distributional records from Cuba. Méndez-Hernández & González-Guillen reported on Polymita “Three new localities of Polymita venusta are uncovered from the northern foothills of Sierra de Boniato in the Santiago de Cuba province. In those, five new populations inhabiting fragmented forests over karstic substratum were found between 238-405 meters above sea level. The rediscovery of a unique color form took place in one colony from the La Luz vicinity. These populations occupy a highly deforested area where the main activities are cattle grazing and agriculture, combined with other anthropic threats. Protected Areas planning for this human highly disturbed zone is nonexistent”.

The second paper by González Guillén et al. presents “New findings of larger slugs from different localities of eastern Cuba, belonging to the family Veronicellidae (Gray, 1840), are revealed. Three of these species could be new to science. This paper verifies the geographic distribution, color forms and sizes, based on the evidence known to date”.

The problem with slugs, especially veronicellids, is the need for molecular studies to ascertain identifications. It has been stated before elsewhere, but is repeated again. Not easy to do, but someone ought to do it, one day…

References:
González Guillén, A. et al. 2021. Large Eastern Cuban Slugs: Overview of an Enigmatic and Forgotten Group. – The Festivus 53(1): 18-25.
Méndez-Hernández, A.A. & González Guillén, A. et al. 2021. New Records of Polymita venusta (Gmelin, 1792) Populations in Northern Foothills of Sierra de Boniato, Santiago de Cuba Province. – The Festivus 53(1): 52-62.

Snails and lichens

An interesting paper on ecology by Reyes-Tur et al. “Snail-lichen interactions have received little attention in tropical ecosystems. Here, we studied the species richness of corticolous lichens with snail grazing traces on host trees inhabited by the Cuban tree snails, Polymita venustaLiguus fasciatus and Hemitrochus lucipeta at La Rinconada, eastern Cuba. We sampled lichen specimens from ground level to 2 m, on the trunks of 15 host trees of eight species, in a 6 000 m2 forest patch, in April 2012. In addition, we sampled snail feces from the three snail species. Most of the tree snail and lichen species were associated with a tree species usually with smooth bark, Senna atomaria. We found 30 lichen species, of which 19 were identified to species, three to genus, and eight remain undetermined. Non-metric multidimensional scaling and χ2 tests showed that the three snail species had different associations with lichen species. Liguus fasciatus is associated with Physcia sorediosa and P. aipoliaH. lucipeta is associated with Platythecium grammitis and an unknown lichen, and P. venusta is associated with Buellia spuria and Chrysothrix candelaris. Evidence from snail grazing damage on lichen species, together with ingested spores from six species, suggested that L. fasciatus and P. venusta are generalist herbivores”.

Although this paper is related to Cuban taxa, the methodology used is also applicable to other species. A nice addition to the biology of these Cuban tree snails.

Reference:
Reyes-Tur, B. et al. 2020. Associations between tree snails and corticolous lichens in a secondary forest on eastern Cuba. – Poeyana 510: 18-26.

Brazilian Megalobulimus

Just published, a new species and a redescription of another one by Fontanelle et al. “Megalobulimus dryades sp. nov. is described from the Atlantic Forest in the Vale do Ribeira region, in the states of Paraná and São Paulo, S-SE Brazil, based on morphology. Representatives of the new species with white peristome and glossy periostracum have been misidentified as Megalobulimus gummatus (Hidalgo, 1870) since the 19th Century. The true M. gummatus is revised and redescribed, and its distribution is here restricted to Rio de Janeiro state. Externally, the new species differs from M. gummatus in having distinct protoconch color and sculpture, teleoconch sculpture marked by strong anastomosing rugosities and malleations, and lighter colored white-greyish head-foot. Internally, it presents distinct jaw and radular features, a talon, and a long convoluted penis bearing two flagella. Additional comparisons with other Brazilian congeneric species are also provided”.

This new species is very similar to another one, M. gummatus (Hidalgo, 1870), and has been confused in the past. As often, the paper is illustrated by excellent anatomical drawings by Luiz Simone, and also Hidalgo’s taxon is well-illustrated.

Reference:
Fontenelle, J.H. et al. 2021. Megalobulimus dryades, a new species from the Atlantic Forest in southeastern Brazil, and redescription of Megalobulimus gummatus(Gastropoda: Strophocheilidae). Papéis Avulsos de Zoologia 61: e20216144.

Suter’s Neotropical type specimens

“In 1900, Henry Suter, a New Zealand malacologist, described six land snail taxa from South America, mostly from Brazil. These taxa received little further attention from malacologists and the unusual depository of its type specimens (New Zealand) caused much confusion in the literature. Suter’s types and taxa are thus revisited in the present work. In summary, the following species are considered valid: Gastrocopta iheringi (Gastrocoptidae), Scolodonta interrupta (Scolodontidae), Radiodiscus compactus, and Radiodiscus patagonicus (Charopidae). Streptaxis tumescens is a junior synonym of Happia vitrina (Scolodontidae) and Pyramidula schuppi is a junior synonym of Rotadiscus amancaezensis (Charopidae)”.

Reference:
Salvador, R.B., 2021. Type specimens of the South American terrestrial gastropods described by Henry Suter. Integrative Systematics 3: 61-68.

Brazilian cave snails

Salvador et al. have just published a paper on molluscs from caves in the interior of Brazil. “Samples of terrestrial gastropods were collected year-round in seven caves in Presidente Olegário municipality, Minas Gerais state, southeastern Brazil, during several expeditions from 2012 to 2014. Twenty-four taxa (plus a single freshwater species), mainly stylommatophorans, were found in the material. The followingspecies are reported for the first time for Minas Gerais state: Alcadia iheringi Wagner, 1910 and Helicina sordida King, 1831 (Helicinidae); Cecilioides consobrina (d’Orbigny, 1841) (Ferussaciidae); Entodina gionensis Morretes, 1940 and Scolodonta interrupta (Suter, 1900) (Scolodontidae); Megalobulimus sanctipauli (Ihering & Pilsbry, 1900) (Strophocheilidae); Drymaeus coarctatus (Pfeiffer, 1845) (Bulimulidae); Habroconus semenlini (Moricand, 1846) (Euconulidae); and Solaropsis aff. rosaria (Pfeiffer, 1849) (Solaropsidae). Furthermore, the species Drymaeus iracema (Simone, 2015) and Drymaeus terreus (Simone, 2015) are synonymized with Drymaeus coarctatus (L. Pfeiffer, 1845)”.

Interesting to see that caves are getting more attention now in the Neotropics, although so far mainly in Brazil. The study has several new records for species and also some new synonymies, notably of species that were previously placed in a separate genus but appear to fall within the variation of the genus Drymaeus. As has been argued before, this genus is very variable and may therefore be misleading during identification. The paper was quickly published and the lay-out is not flawless, and some literature cited in the text is not mentioned in the references.

Reference:
Salvador, R.B. et al. 2021. Terrestrial Gastropoda from the caves of Presidente Olegário, southeastern Brazil. Biota Neotropica 21(2): e20201169.

Systrophia argentina re-found

Systrophia argentina (Strobel, 1874) n. comb. is here re-described 150 years after its discovery. The specimens were found in the Argentine Precordillera (Quebrada San Isidro, Mendoza province, Argentina), at 2.000 m, near the typical locality of the species, here restricted to the Angostura or garganta (gullet) of Villa Vicencio and Casa de Piedra. It is the southernmost distribution of the genus. This snail has a shell of medium size, planispiral, with six whorls; radula with central plate tricuspid, and latero-marginal teeth aculeate, formula: 13 – C – 13; vagina short, spermathecal duct reaching the distal extreme of the vagina, near the atrium; penial sheath long, penis occupying most of the penial sheath, epiphallus with a retractor muscle adhered to its extreme, large and quadrangular gland attached to the penial sheath; atrium very short. S. argentina is the only species ofSystrophia L. Pfeiffer, 1855 in Argentina, being the most austral distribution of the genus”.

Reference:
Miquel, S.E., 2020. Finding of Systrophia argentina n. comb. in the Argentine Precordillera (Mendoza province) a century and a half after its description (Mollusca: Gastropoda: Scolodontoidea). — Revista del Museo Argentino de Ciencias Naturales, n. s. 22(2): 167-172.