Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Cadmium is a toxic metal for zooplankton that produces deformations. Therefore, we used two native zooplankton species from Quintana Roo, Mexico, to obtain data regarding cadmium toxicity including the threshold concentration for observable morphological alterations and the percentage of organisms with morphological alterations at the exposure concentrations. We used the rotifer Rotaria sp. and the oligochaeta Aeolosoma hemprichi, both fed with the alga Nannochloropsis oculata. Then, Rotaria sp. and A. hemprichi were exposed to a cadmium concentration range from 0.05 to 10.0 mg L-1. The LC50 for cadmium in Rotaria sp. was 0.7 mg L-1, whereas in A. hemprichi it was 3.38 mg L-1. Cadmium at 0.5 mg L-1 for ≤24 h induced morphological alterations in the lorica of rotifers, foot deformations, and constriction in the middle part of the body. In oligochaetes, damage to the epidermis was noted. The threshold concentration where deformations appeared in rotifer was 0.3 mg L-1 at 24 h and in oligochaeta was 0.5 mg L-1 at 30 min.

Hypericum is a genus belonging to the Hypericaceae family, which has 469 species of herbs, trees and shrubs. Two sections in particular: Brathys and Trygynobrathys are an integral part of the Paramo vegetation type. Taking into account its composition and the antidepressant activity properties reported for this plant, the histochemistry and anatomy of Hypericum juniperinum collected in the Colombian Paramo is described. To achieve this goal, the aerial organs (stems, leaves and flowers) of Hypericum juniperinum were collected in the village Arbolocos of the municipality of Cuitiva, Boyacá (voucher code No.589611, COL). For the anatomical analysis, the organs of H. juniperinum were processed with fixation techniques, incorporation in paraffin, cutting in microtome and staining with Astra-blue and basic fuchsin; for the histochemical analysis freehand cuts were made with specific stains for lipids, phenol compounds, alkaloids and pectins. The anatomy of the organs of H. juniperinum should be understood in the context of the living conditions of the Paramo. The leaves are highly xeromorphic as they are chartaceous, rosette-shaped, convolute and upright, with parenchyma in bistratified palisade, thickened walls, thick cuticle and epicuticular wax in the two foliar epidermis, stomata on the abaxial side and with epidermal chamber. However, it has some mesomorphic characteristics such as parenchymatic bundle sheath and loose spongy parenchyma. Hypericum juniperinum presents translucent glands in leaves, calyx and gynoecium, and lacks black glands typical of the Hypericum section where the medicinal plant Hypericum perforatum belongs. Histochemical analysis showed lipids in leaf canals, radial parenchyma of the stem and in some floral structures. Phenolic compounds were detected along the leaf, in the phloem of the stem and in the anthers. Hypericum juniperinum lacks alkaloids and presents pectins in the parenchyma of the sheath surrounding the vascular bundle of the leaf. In this way, the present work contributes by relating the metabolites with their distribution in the tissues of this native species. In addition, the anatomy showed that H. juniperinum has characteristics of a plant from Paramo. The description given here could be used as a preliminary monograph of plants from the Hypericum genus with promising therapeutical properties.

Abstract: The Dichopetala genera group was proposed recently after revision of the genus Dichopetala Brunner von Wattenwyl, 1878. Currently, the group consists of eight genera and 44 species distributed from southern United States to southern Mexico. This generic arrangement was based only on morphological evidence, and was accompanied by discussions on the new erected genera, for which their monophyly was not tested. In this study we assessed the phylogenetic relationships among representative species of the eight genera of the Dichopetala genera group. For this, we generated DNA sequences for one mitochondrial (Cytochrome oxidase I: COI) and two nuclear (28s, Histone III: H3) markers, and included specimens of other phaneropterine genera to test the monophyly of the ingroup. Our results support the monophyly of the Dichopetala genera group and the monophyly of genera Dichopetala, Obolopteryx and Planipollex. In addition, genera Rhabdocerca, Acanthorintes, and Pterodichopetala were recovered as paraphyletic. The mitochondrial markers also suggest that the widely distributed genera Rhabdocerca and Acanthorintes, may actually contain various overlooked species. A more robust phylogenetic and morphological definition of some of the genera involved is provided.

Abstract. Introduction: Ecology and natural history of neotropical land snails is almost unknown. Objetive: In this paper I analyse the population dynamics of Tikoconus (Tikoconus) costarricanus Barrientos, in prep., an understory endemic euconulid. Methods: I compared T. costarricanus’ 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 = 0.000, **), amount (Spearman correlation, r = 0.3922, n = 232, p = 0.000, **) and depth (Spearman correlation, r = 0.2543, n = 232, p = 0.000, **). This relationship is explained by the high and stable humid environment provided by leaf litter. During the drier months some specimens migrate from the foliage to the leaf litter. 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: Although no conclusive, these data point to a fragile species susceptible to habitat and climate change. Restorations techniques should consider leaf litter features in order to protect endemic neotropical humid dependent diversity.

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 sensu stricto with seven 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.