Tag Archives: costa rica

Demography Tikoconus

Due to oversight I missed the recent paper by Barrientos on the biology one of the new euconulid species; time to report it now.

Introduction: Ecology and natural history of neotropical land snails is almost unknown. Objetive: In this paper, I analyse the population dynamics of Tikoconus (Tikoconus) costaricanus Barrientos, an understory endemic euconulid.
Methods: I compared T. costaricanus’ demography patterns in tropical montane forests in central Costa Rica in three habitats with different restoration techniques: a mature forest, a secondary forest and a Cuppressus lusitanica plantation. I collected data in three month periods during a year. I analysed population size in relation with habitat, sampling date, leaf litter humidity, depth and quantity; and specimen size in relation with habitat and sampling date. I also kept some specimens in terraria and described part of their natural history.
Results: The species is more abundant in mature forest (Ø = 0.174 ind/m2). The number of specimens in each habitat was constant throughout the year (Kruskall-Wallis = 2.0118, p = 0.57, NS) and hatching occurs in the middle and last months of the rainy season (Kruskall-Wallis = 17.3061, P = 0.00061, **). Number of specimens is related with leaf litter humidity (Spearman correlation, r = 0.3524, n = 232, P < 0.001, **), quantity (Spearman correlation, r = 0.3922, n = 232, P < 0.001, **) and depth (Spearman correlation, r = 0.2543, n = 232, P < 0.001, **). This relationship is explained by the high and stable humid environment provided by leaf litter. Some specimens migrate from foliage to leaf litter during the drier months. Eggs (Ø = 1mm) are laid on moss or soil and the young spend the first 2 or 3 weeks of their life on moss. Egg masses are small (Ø = 4 eggs), and shells look bubbly. Egg development time (20 days) was longer than in other tropical species. Adult pigmentation appears around two months after hatch. In the only case observed, egg laying began 5 months after hatching and the specimen lived 9 months.
Conclusions: Restorations techniques should consider leaf litter features in order to protect endemic neotropical humid dependent diversity
“.

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This is an excellent ecological study of one of the new species recently described by her. And although the resulting data are not completely unexpected given the (very scarce) literature data, this study may have wider application than just the Costa Rican case. Albeit these studies are difficult to execute (especially if species are small and not occurring in abundant numbers), I hope that more Neotropical malacologists with endeavour them during field work.

Reference:
Barrientos, Z., 2019. Demography of the land snail Tikoconus (Tikoconus) costaricanus (Stylommatophora: Euconulidae) in tropical low montane and premontane forests, Costa Rica. – Revista de Biología Tropical, 67(6): 1449-1460.

New Costa Rican euconulids

Just published: a paper by Barrientos with new data on Costa Rican Euconulidae. The abstract is as follows:

Introduction: The family Euconulidae is circumglobal, but only one subfamily, the Euconulinae, occurs in the American continent. Fourteen native euconulids, in three genera, have been reported from Costa Rica.
Objective: In this paper I describe Tikoconus, a new genus of Euconulinae endemic to Costa Rica.
Methods: I dissected alcohol-preserved euconulids collected in Costa Rica. I took photographs or electron micrographs or drew the shell, external anatomy, reproductive system, mantle cavity organs and radula.
Results: The genus Tikoconus can be recognized by its semislug appearance and very thin and often flexible subglobose to subglobose-depressed external shell. Other distinctive features of the genus are a lack of black dots on the mantle and the presence of at least some dark blotches on the subpedal groove band. Internally, the urethra has a Z-shaped prolongation that almost reaches the mantle collar. The reproductive system has a distinctive external C-shaped penial gland that surrounds half of the penis circumference and is attached to the penis and to the penial caecum, but not connected to them by ducts. Also, there is an internal mono- or bi-lobulated extension in the penis. The epiphallus has a verge that enters into the penis. The penial sheath surrounds part of the penis, the epiphallus base and the penial retractor muscle insertion, but leaves the penial gland and the penis caecum free. The gametolytic gland is absent. I described two new subgenera: Tikoconus with six new species-T. (T.) costaricanus sp.n. (type species), T. (T.) onca sp.n., T. (T.) andresi sp.n., T. (T.) katyae sp.n., T. (T.) alosii sp.n., T. (T.) subsilvanus sp.n.; and Bribriconus with only one species-T. (B.) thompsoni sp.n. All species have restricted distributions and are endemic to particular watersheds, except for T. costaricanus which occurs nearly throughout the central mountains of Costa Rican. This genus inhabits very wet, little disturbed tropical forests from 400 to 2 500 masl on the Atlantic slope and from 760 to 2 500 masl on the Pacific slope. The genus Velifera, the other semislug euconulid reported from Costa Rica, is kept as a valid taxon and I choose the specimen ANSP 48765 as lectotype of Velifera gabbi with the purpose of clarifying the application of the name to a taxon.
Conclusion: A new euconulid genus and seven species were described.

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This is thorough paper on this less-known family which occurs in different Neotropical countries. A key is included for the species of the new genus. The paper provides interesting data on the anatomy and ecology of these species, data which are hardly known for other representatives of this family in the Neotropics.

Reference:
Barrientos, Z., 2019. A new genus of semislugs (Stylommatophora: Euconulidae) from Costa Rica and a review of the genus Velifera (Stylommatophora: Euconulidae). Revista de Biologia Tropical, 67 (6): 1313-1358.

Drymaeus tripictus ecology

Zaidett Barrientos have made an important contribution to the ecology of Neotropical snails to study the ecology and biology of Drymaeus tripictus (Albers, 1857) in Costa Rica. The abstract of the recent paper is as follows: “Very little is known about the ecology and biology of Drymaeus tripictus, an extremely rare and endemic land snail species from Costa Rican highlands. I studied the ecology and reproductive biology of D. tripictus from April 2009 through June 2010 in an old forest, a young forest and a Cupressus lusitanica plantation in central Costa Rica. Every three months I visited each habitat and collected specimens in 20 random sampling plots (3×3 m2 each). I observed the snail’s activity and microhabitat preference in the field, and in the labora- tory I recorded high definition videos of its mating behavior and analyzed reproductive morphology with light microscopy. The snail is more abundant in the old forest (0.017 ind./m2) and prefers leaves with little epiphyllous cover (0-25 % cover, chi-square test, p <0.0001). During the dry season the snails become active between 20:00 pm and 8:00 am (chi-square = 22.65, df=3, p < 0.0001); they are inactive mainly during the afternoon (11:00 am to 16:59 pm). I found active individuals mostly on the upper side of leaves, where they feed (Chi-square =6.76, df=1, p = 0.0093). Mating is unilateral, by shell mounting, with cryptic phallus intromission and without role switching or multiple mating. Its reproductive system is morphologically similar to that of Drymaeus costaricensis. Mating behavior is as expected for snails with high-spired shells, except for the lack of role switching. The density of D. tripictus is low even when compared with other endangered bulimulids”.

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A very interesting paper, which I had the pleasure to review as a draft (although not acknowledged).

Reference:
Barrientos, Z., 2016. Reproductive system, mating behavior and basic ecology of an extremely rare tropical snail: Drymaeus tripictus (Stylommatophora: Bulimulidae). – Revista de Biología Tropical, 64(1): 55–68.

A snail with an U-loop

Cornu aspersum (O.F. Müller, 1774) is a common European snail with a ground colour of yellowish brown , and mostly with some darker spiral bands and irregular light and dark blotches (Jansen, 2015). Recently in a Dutch zoo a new tropical greenhouse was installed with plants imported from Costa Rica. Herman Creemers sent me a picture of snails collected in this greenhouse (on the right side), together with some specimens from the Netherlands (on the left side). He wondered if this species was known from Costa Rica or not.

p1130112

Barrientos (2003) has given an overview of Costa Rican species and said: “El escargot, Helix aspersa [the old name], fue introducido has más de 100 años y está restringido a jardines urbanos en San José”; the species is thus more than a century present in Costa Rica, but still restricted to gardens in the capital. The different coloration of shells presumably originating from Costa Rica, imported together with plants, is somewhat different. This might be due to the prolonged isolation, but only detailed DNA research could tell whether some divergence has occurred or not.

References:
Barrientos, Z., 2003. Estado actual del conocimiento y la conservación de los moluscos continetales de Costa Rica. – Revista de Biologia Tropical 51, Supplemento 3: 285–292.
Jansen, A.W., 2015. Veldgis slakken en mossels. Zeist, KNNV, 272 pp.

Ecology of Costa Rican Drymaeus

Recently a very interesting paper has been published by Zaidett Barrientos (2016), describing the genitalia, mating behaviour and providing ecological data of the Costa Rican species Drymaeus tripictus (Albers, 1857).

The abstract reads “Very little is known about the ecology and biology of Drymaeus tripictus, an extremely rare and endemic land snail species from Costa Rican highlands. I studied the ecology and reproductive biology of D. tripictus from April 2009 through June 2010 in an old forest, a young forest and a Cupressus lusitanica plantation in central Costa Rica. Every three months I visited each habitat and collected specimens in 20 random sampling plots (3×3 m2 each). I observed the snail’s activity and microhabitat preference in the field, and in the laboratory I recorded high definition videos of its mating behavior and analyzed reproductive morphology with light microscopy. The snail is more abundant in the old forest (0.017 ind./m2) and prefers leaves with little epiphyllous cover (0-25 % cover, chi-square test, p <0.0001). During the dry season the snails become active between 20:00 pm and 8:00 am (chi-square = 22.65, df=3, p < 0.0001); they are inactive mainly during the afternoon (11:00 am to 16:59 pm). I found active individuals mostly on the upper side of leaves, where they feed (Chi-square =6.76, df=1, p = 0.0093). Mating is unilateral, by shell mounting, with cryptic phallus intromission and without role switching or multiple mating. Its reproductive system is morphologically similar to that of Drymaeus costari- censis. Mating behavior is as expected for snails with high-spired shells, except for the lack of role switching. The density of D. tripictus is low even when compared with other endangered bulimulids”.

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Supplementary files on the journal’s website are supposed to be videos of the mating, but these were unavailable at the time of writing.

Reference:
Barrientos, Z., 2016. Reproductive system, mating behavior and basic ecology of an extremely rare tropical snail: Drymaeus tripictus (Stylommatophora: Bulimulidae). – Revista  de Biologia Tropical 64 (1): 55–68.

Invasive Deroceras slugs

Just published: a paper by Hutchinson et al. (2014) on invasive Deroceras slugs. The abstract reads:

The article reviews distribution records of Deroceras invadens (previously called D. panormitanum and D. caruanae), adding significant unpublished records from the authors’ own collecting, museum samples, and interceptions on goods arriving in the U.S.A. By 1940 D. invadens had already arrived in Britain, Denmark, California, Australia and probably New Zealand; it has turned up in many further places since, including remote oceanic islands, but scarcely around the eastern Mediterranean (Egypt and Crete are the exceptions), nor in Asia. Throughout much of the Americas its presence seems to have been previously overlooked, probably often being mistaken for D. laeve. New national records include Mexico, Costa Rica, and Ecuador, with evidence from interceptions of its presence in Panama, Peru, and Kenya. The range appears limited by cold winters and dry summers; this would explain why its intrusion into eastern Europe and southern Spain has been rather slow and incomplete. At a finer geographic scale, the occurrence of the congener D. reticulatum provides a convenient comparison to control for sampling effort; D. invadens is often about half as frequently encountered and sometimes predominates. Deroceras invadens is most commonly found in synanthropic habitats, particularly gardens and under rubbish, but also in greenhouses, and sometimes arable land and pasture. It may spread into natural habitats, as in Britain, South Africa, Australia and Tenerife. Many identifications have been checked in the light of recent taxonomic revision, revealing that the sibling species D. panormitanum s.s. has spread much less extensively. A number of published or online records, especially in Australia, have turned out to be misidentifications of D. laeve.

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Reference:

Hutchinson, J., Reise, H. & Robinson, D., 2014. A biography of an invasive terrestrial slug: the spread, distribution and habitat of Deroceras invadens. NeoBiota 23: 17–64. Available at http://neobiota.pensoft.net/articles.php?id=4006.