Estudios entomofaunísticos en el archipiélago del Cabo de Hornos: III.- Composición y estructura de la entomofauna de suelo-superficie asociada a bosques y turbales en caleta Toledo (isla Deceit: 55º49ºS-67º06'O)
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1983
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Se informa de la composición y estructura de la fauna entomológica capturada en formaciones de bosque y turbal en caleta Toledo (isla Deceit, archipiélago del Cabo de Hornos) sobre la base de material recolectado durante parte de la primavera de 1982. La composición específica y la estructura se estudian considerando las densidades de captura, la constancia espacial y las relaciones de dominancia numérica. Para el análisis cuantitativo se aplican diversos criterios: similitud, riqueza específica, diversidad, sobreposición y uniformidad. El conjunto presenta una gran semejanza con la entomofauna registrada en otras islas del archipiélago (Lanfranco, 1980; 1981). La muestra está compuesta de 52 especies de los órdenes Díptera, Coleóptera, Hymenoptera, Psocoptera, Homoptera y Hemiptera. El orden Díptera aporta el mayor número de especies (48,1%) en tanto el orden Coleóptera contribuye con el mayor número de ejemplares (64,2%). Las especies dominantes generales son los carábidos Ceroglossus suturalis y Cascellius gravesi y el micetofílido Mycomya sp. nov., que constituyen el 61,48% del total de los insectos capturados. Otras consideraciones cualitativas se refieren a la falta de endemismo insular y al predominio de géneros de origen paleoantarrico. La similitud biocenótica entrega valores superiores entre formaciones vegetales semejantes por la influencia de elementos comunes y una baja similitud entre ambientes diferentes. La determinación de grupos recurrentes define conjuntos de especies con una clara tendencia de fidelidad ambiental. Respecto a la estructura, los resultados de isla Deceit revelan una mayor complejidad en los ambientes de bosque. Ellos poseen la mayor diversidad y uniformidad y la menor dominancia. En los ambientes de turbal los resultados denotan la influencia del dominante C. suturalis.
De situaciones comparables en otras islas del archipiélago ha sido posible insinuar tendencias respecto a algunos parámetros poblacionales en relación con la gradiente latitudinal.
Composition and structure of the entomological fauna captured during part of the spring of 1982 in forest and moorland communities in caleta Toledo are presented (isla Deceit, Cabo de Hornos archipelago). These topics are studied on based of capture density, spatial constance and numeric dominance relations. For the cuantitative analysis several criterions are applied: similarity, species richness, diversity, overlap and uniformity. The assemblage presents a great similarity with the entomofauna registrad in other islands of Cabo de Hornos archipelago (Lanfranco 1980, 1981). The sample has 52 species of the following orders: Diptera, Coleoptera, Hymenoptera, Psocoptera, Homoptera and Hemiptera. Diptera contribute with most of the species (48,1%) while Coleoptera with most of the individuals (64,2%). The dominant species are the carabids Ceroglossus suturalis and Cascellius gravesi, and the micetofilid Mycomya sp. nov., which constitute 61,48% of all the insects captured. Other cualitative considerations are the lack of insular endemism and the predominance of paleoantarctic genera. The biocenotic similarity gave the highest values between similar vegetational formations by the influence of common species, and a low similarity between different communities. The recurrent groups determine species assemblage with a clear trend of environmental fidelity. In respect to the structure, the Deceit island results show a great complexity in forests. They have the highest diversity and uniformity and the lowest dominance. In the moorland communities results indicate a great influence of dominant: C. suturalis. In comparable situations with other islands of the archipelago, it is possible to suggest tendencies on some population parameters related to the latitudinal gradient.
Composition and structure of the entomological fauna captured during part of the spring of 1982 in forest and moorland communities in caleta Toledo are presented (isla Deceit, Cabo de Hornos archipelago). These topics are studied on based of capture density, spatial constance and numeric dominance relations. For the cuantitative analysis several criterions are applied: similarity, species richness, diversity, overlap and uniformity. The assemblage presents a great similarity with the entomofauna registrad in other islands of Cabo de Hornos archipelago (Lanfranco 1980, 1981). The sample has 52 species of the following orders: Diptera, Coleoptera, Hymenoptera, Psocoptera, Homoptera and Hemiptera. Diptera contribute with most of the species (48,1%) while Coleoptera with most of the individuals (64,2%). The dominant species are the carabids Ceroglossus suturalis and Cascellius gravesi, and the micetofilid Mycomya sp. nov., which constitute 61,48% of all the insects captured. Other cualitative considerations are the lack of insular endemism and the predominance of paleoantarctic genera. The biocenotic similarity gave the highest values between similar vegetational formations by the influence of common species, and a low similarity between different communities. The recurrent groups determine species assemblage with a clear trend of environmental fidelity. In respect to the structure, the Deceit island results show a great complexity in forests. They have the highest diversity and uniformity and the lowest dominance. In the moorland communities results indicate a great influence of dominant: C. suturalis. In comparable situations with other islands of the archipelago, it is possible to suggest tendencies on some population parameters related to the latitudinal gradient.
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Entomofauna, Caleta Toledo, Isla Deceit
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Anales del Instituto de la Patagonia, Vol. 14, pp. 119-131, 1983.