New record for the distribution of the colonial hydroid Cordylophora caspia (Pallas, 1771) (Cnidaria: Hydrozoa) in Argentina

Cordylophora caspia is a colonial, athecate hydroid inhabiting both in freshwater and brackish habitats. Its global distribution is in part due to its ability to tolerate a wide range of salinity. It is considered an invasive species and its control is widely studied because of the industrial and ecological problems it causes in many environments. We report for the first time the occurrence of this hydrozoan in Nahuel Rucá Lake (Buenos Aires province, Argentina) with some notes on its internal and external morphology.Fil: Deserti, Maria Irene. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Escalante, Alicia Haydee. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Acuña, Fabian Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

Statistical analysis on the cnidome of genus Hydra using Generalized Linear Models

In the systematics of cnidarians, the different types of cnidocysts are considered an important taxonomic character. In Hydra, the four types of cnidocysts found in the ectoderm, concentrated in tentacles and their measurements, together with other morphological and reproductive characteristics, are very important for the taxonomy of the species. In this study, we explore in detail the biometric and statistical characteristics of the cnidome of three species of Hydra collected in three different environments for each climate season. A total of 17,378 capsules were measured. We used ANOVA test and Generalized Linear Model to analyze the distribution and differences reflected in each cnidome, considering the factors “individuals”, “season”, “lagoon” and “species”. The results were clear: the cnidome keep specific information that, together with other taxonomic characteristics, allows us to discern between species of different groups. The same happens with cnidome of the same species but from different lagoons or climatic seasons: we observed a variation of parameters for each type of cnidocyst that could differentiate “ecological races”, since these differences are not enough to declare different species

Hydra vulgaris Pallas, 1766, (=Hydra attenuata) (Cnidaria; Hydrozoa) from the Los Padres Lagoon (Buenos Aires province, Argentina)

This paper reports the presence of Hydra vulgaris Pallas, 1766, from the Los Padres Lagoon (Buenos Aires province, 37º 56’ S; 57º 45’ W), and represents the first record of this species for Argentina. The study showed that morphological characters coincide with what has been reported by other authors, such as stenoteles 10-3 µm (15.48 ± 0.44; mean ± standard deviation) long and 6-20 µm (11.75 ± 0.82) in diameter, holotrichous isorhiza 9-14 µm (11.96 ± 0.56) long and 4-7 µm (5.45 ± 0.31) in diameter, atrichous isorhiza 5-13 µm (8.00 ± 0.87) long and 3-8 µm (4.80 ± 0.38) in diameter and the desmonemes 6-12 µm (8.24 ± 0.67) long and 4-8 µm (5.70 ± 0.43) in diameter. The colour of this species is brown; the column oscillates between 1.98-9.88 × 0.31-1.82 mm and their tentacles, ranging from 6 to 9, have a relative length of ~¾ the length of the column. This species is dioecious; young buds have five or six tentacles, with discontinuous growth

Sierras del Tandil. First Meeting of Morpfological Sciences.

Las hidras son los cnidarios dulceacuícolas por excelencia y el ejemplo clásico de la forma pólipo dentro de dicho phylum. Sin embargo existe aún una gran confusión en lo que concierne a la taxonomía del género, ya que muchas especies presentan variaciones morfológicas que dificultan su identificación.Las hidras del hemisferio sur han sido poco investigadas, por lo que no se conoce con certeza cuales son las especies presentes y si éstas pertenecen a los grupos taxonómicos existentes hasta el momento. El presente estudio analiza la presencia de Hydra vulgaris en dos cuerpos lagunares distintos de la provincia de Buenos Aires (Argentina); lagunas ?Los Padres? y Nahuel Rucá, registrando para una de ellas dos formas distintas en su nematocisto holotrico isorriza.Fil: Deserti, Maria Irene. Universidad Nacional de Mar del Plata. Facultad de Cs.exactas y Naturales. Departamento de Cs.marinas. Laboratorio de Biologia de Cnidarios; Argentina;Fil: Zamponi, Mauricio Oscar. Universidad Nacional de Mar del Plata. Facultad de Cs.exactas y Naturales. Departamento de Cs.marinas. Laboratorio de Biologia de Cnidarios; Argentina;Fil: Escalante, Alicia Haydee. Universidad Nacional de Mar del Plata. Facultad de Cs.exactas y Naturales. Departamento de Biologia. Laboratorio 13 (ex Lab Ecologia de Agua Continentales); Argentina

Trophic ecology and diet of Hydra vulgaris (Cnidaria; Hydrozoa)

Hydra is a genus of common, sessile, solitary freshwater cnidarians, which are defined as carnivorous and efficient predators. The purpose of this study was to obtain information on the feeding habits and diet of Hydra vulgaris collected from its natural habitat in Nahuel Rucá Lake (Buenos Aires Province, Argentina). We found three categories of food items in the coelenteron: Algae, fungi, and small invertebrates. Algae dominated the diet in terms of abundance and frequency of occurrence, but their volumetric contribution was almost negligible, as was their possible nutritional value. Invertebrate prey captured, using active predation, represented the major volumetric contribution, with four different taxa found. The detection of phytoplankton in the gastral cavities reveals the input of some organisms present in the surrounding waters in addition to the invertebrates. This information is novel, since studies on the natural diet of Hydra are very scarce.Fil: Deserti, Maria Irene. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Esquius, Karina Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Escalante, Alicia Haydee. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Acuña, Fabian Horacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin