Patrones de abundancia de cinco especies de arañas lobo (Araneae: Lycosidae) en dos ambientes del Parque Nacional Mburucuyá, Corrientes, Argentina

RUBIO GONZALO; MINOLI IGNACIO; PIACENTINI LUIS

BRENESIA

Museo Nacional de Costa Rica

Año: 2007 vol. 67 p. 59 - 67

0304-3711

Two environments of Mburucuyá National Park (hygrophilous woodland and savannah-park) were considered to analyze patterns of abundance of the Trochosippa anomala, Alopecosa humilis, Lycosa thorelli, Hogna bivittata and Trochosa sp. The spiders were collected by pitfall trappings and sieve of dead leaves using seasonal samplings (2003-2004). Temporary and spatial abundance patterns, as well as aspects related to demographic structures and the contribution of collecting techniques to the abundance of these species were analyzed. A total of 320 specimens were collected. Wolf spiders species studied here are biotically sympatric for both environments, except for A. humilis and H. bivittata which were exclusively restricted to the savannah-park. In this environment A. humilis was found to be more abundant while T. anomala was more abundant in the hygrophilous woodland, presenting peaks in winter. In the savannah, the same temporary pattern was observed in A. humilis, T. anomala and H. bivittata, being more abundant in autumn. Also, an aggregated distribution of these species was observed in both environments (I.D.>1). Immature spiders represented the 85,3% of all the individuals gathered, and only in spring do adults surpass immatures in number. Female were more abundant than males (55,3%), except in spring. From all the spiders gathered, 61,2% were obtained using sieve of dead leaves and 38,8% by pitfall trappings. In summer, autumn and winter, the gathering was greater using sieve of dead leaves than in spring when gathering was mainly obtained by pitfall trappings. It is concluded that there are spatial-temporary variations in the abundance, and that environments may control the studied species and certain populations. It is estimated that L. thorelli could flow between environments along the year depending on their development stage.