Occurrence and morphological variability of Hydra (Hydroida: Hydridae) in freshwater bodies of Southeast of Buenos Aires Province, Argentina

Hydra constitutes a monophyletic clade of sessile and solitary polyps that occur on all continents except Antarctica. Despite its widespread presence in freshwater habitats, Hydra requires reasonably unpollut- ed conditions for survival, making its presence a reliable indicator of good water qualit...

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Main Authors: Maria Irene Deserti, Fabian Horacio Acuña
Format: Article
Language:Spanish
Published: Fundación Mguel Lillo 2025-08-01
Series:Acta Zoológica Lilloana
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Online Access:https://www.lillo.org.ar/journals/index.php/acta-zoologica-lilloana/article/view/2227
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author Maria Irene Deserti
Fabian Horacio Acuña
author_facet Maria Irene Deserti
Fabian Horacio Acuña
author_sort Maria Irene Deserti
collection DOAJ
description Hydra constitutes a monophyletic clade of sessile and solitary polyps that occur on all continents except Antarctica. Despite its widespread presence in freshwater habitats, Hydra requires reasonably unpollut- ed conditions for survival, making its presence a reliable indicator of good water quality and a certain degree of ecosystem conservation. Since their discovery, these polyps have become valuable biological models due to their morphological simplicity, global distribution, and low maintenance requirements in the laboratory conditions, enabling experiments on regeneration, reproduction, senescence, cellular differ- entiation, among other processes. All Hydra species are clustered into four morphological groups: viridissima (green), vulgaris (common), oli- gactis (stalked), and braueri (gracile). Species in the viridissima group are green due to the presence of intracellular symbiotic algae, whereas the brown hydras (braueri, oligactis, and vulgaris) lack such endosym- bionts. The oligactis and braueri groups are restricted to the Northern Hemisphere, while the viridissima and vulgaris groups include cosmo- politan species. To date, only five published records documenting the presence of Hydra in Argentina are available in the scientific literature. In the present study, we report six new occurrences from four wetlands in the southeastern region of Buenos Aires Province: two each for H. viridissima, H. vulgaris, and H. vulgaris pedunculata. The study includes a quantitative morphological analysis (body measurements, cnidome, and reproductive structures) to assess intraspecific variation among pop- ulations from different freshwater bodies. These findings expand the known distribution of Hydra in South America and provide reference data for future ecological and taxonomic studies.
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spelling doaj-art-9e761cc2604f4531906fa418cfd901fb2025-08-22T20:05:29ZspaFundación Mguel LilloActa Zoológica Lilloana1852-60982025-08-0110.30550/j.azl/2227Occurrence and morphological variability of Hydra (Hydroida: Hydridae) in freshwater bodies of Southeast of Buenos Aires Province, ArgentinaMaria Irene Deserti0Fabian Horacio Acuña1Laboratorio de Biología de Cnidarios (LABIC), Facultad de Cs. Exactas y Naturales (FCEyN), Universidad Nacional de Mar del Plata (UNMdP)Laboratorio de Biología de Cnidarios (LABIC), Facultad de Cs. Exactas y Naturales (FCEyN), Universidad Nacional de Mar del Plata (UNMdP) Hydra constitutes a monophyletic clade of sessile and solitary polyps that occur on all continents except Antarctica. Despite its widespread presence in freshwater habitats, Hydra requires reasonably unpollut- ed conditions for survival, making its presence a reliable indicator of good water quality and a certain degree of ecosystem conservation. Since their discovery, these polyps have become valuable biological models due to their morphological simplicity, global distribution, and low maintenance requirements in the laboratory conditions, enabling experiments on regeneration, reproduction, senescence, cellular differ- entiation, among other processes. All Hydra species are clustered into four morphological groups: viridissima (green), vulgaris (common), oli- gactis (stalked), and braueri (gracile). Species in the viridissima group are green due to the presence of intracellular symbiotic algae, whereas the brown hydras (braueri, oligactis, and vulgaris) lack such endosym- bionts. The oligactis and braueri groups are restricted to the Northern Hemisphere, while the viridissima and vulgaris groups include cosmo- politan species. To date, only five published records documenting the presence of Hydra in Argentina are available in the scientific literature. In the present study, we report six new occurrences from four wetlands in the southeastern region of Buenos Aires Province: two each for H. viridissima, H. vulgaris, and H. vulgaris pedunculata. The study includes a quantitative morphological analysis (body measurements, cnidome, and reproductive structures) to assess intraspecific variation among pop- ulations from different freshwater bodies. These findings expand the known distribution of Hydra in South America and provide reference data for future ecological and taxonomic studies. https://www.lillo.org.ar/journals/index.php/acta-zoologica-lilloana/article/view/2227freshwater cnidariansintraspecific variationwetlands
spellingShingle Maria Irene Deserti
Fabian Horacio Acuña
Occurrence and morphological variability of Hydra (Hydroida: Hydridae) in freshwater bodies of Southeast of Buenos Aires Province, Argentina
Acta Zoológica Lilloana
freshwater cnidarians
intraspecific variation
wetlands
title Occurrence and morphological variability of Hydra (Hydroida: Hydridae) in freshwater bodies of Southeast of Buenos Aires Province, Argentina
title_full Occurrence and morphological variability of Hydra (Hydroida: Hydridae) in freshwater bodies of Southeast of Buenos Aires Province, Argentina
title_fullStr Occurrence and morphological variability of Hydra (Hydroida: Hydridae) in freshwater bodies of Southeast of Buenos Aires Province, Argentina
title_full_unstemmed Occurrence and morphological variability of Hydra (Hydroida: Hydridae) in freshwater bodies of Southeast of Buenos Aires Province, Argentina
title_short Occurrence and morphological variability of Hydra (Hydroida: Hydridae) in freshwater bodies of Southeast of Buenos Aires Province, Argentina
title_sort occurrence and morphological variability of hydra hydroida hydridae in freshwater bodies of southeast of buenos aires province argentina
topic freshwater cnidarians
intraspecific variation
wetlands
url https://www.lillo.org.ar/journals/index.php/acta-zoologica-lilloana/article/view/2227
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