Tag Archives: euconulidae

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.

Determinanda (3): Euconulus

Adri??n Gonz??lez spotted this species, presumably an Euconulus, on a photographing trip in northern Ecuador.
These photographs were taken in Prov. Sucumbios, at La Bonita.

Material from Euconulus was observed by Adri??n between 1000-3500 m in very humid areas, in cloud forests and along river streams.

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