Population Dynamics of an Isolated Population of the Harvestman Ilhaia Cuspidata (Opiliones, Gonyleptidae), in Araucaria Forest (Curitiba, Paraná, Brazil)

Abstract

The harvestman Ilhaia ciispidata was studied in Curitiba, state of Parana, Brazil. The site studied is a 30,000 forest remnant of Araucaria forest surrounded by houses. Harvestmen were sampled 21 times over 14 months (June 1997-August 1998; at intervals of 21-30 days. The population size was estimated by Fisher-Ford and Jolly methods, and did not vary considerably from autumn (June) to spring (November 1997). However, it increased rapidly (300 %) during late spring and summer (December-March). The lowest population size estimated was 1,429 adults/subadults, during the winter (June 1997) and, the highest was 14,445 during the autumn (April 1998). The recapture rates ranged from 16%-41%. The sex ratio observed in all sampling periods was 1:1. The density varied from 0.05 (winter) to 0.47 adult + subadults/m^ (autumn). The extremely different abundances observed between seasons could have been influenced by temperature. The immatures were observed all year, suggesting a continuous reproduction, but they were much more abundant during spring and summer. Ecological aspects including aggregation, individual movement and life span were also discussed.

The harvestmen fauna (Arachnida: Opiliones) of the Parque Estadual Carlos Botelho, and the Floresta Nacional de Ipanema, São Paulo, Brazil

“…In FLONA Ipanema, Mischonyx squalidus was the dominat species, representing 23.6% of individuals collected, while the PE Carlos Botelho, this species represented only 1.5% of the total. Mischonyx is recognized a species of harvestmen associated to human disturbance in the environment (Mestre & Pinto-da-Rocha 2004). The difference between the abundances of the species may reflect the environmental conditions of the parks.…”

Spatial variation in phylogenetic diversity of communities of Atlantic Forest harvestmen (Opiliones, Arachnida)

“…The basic aspects of their biology are known, for instance their nocturnal and cryptic habits, and their dependence on humidity (Pinto‐da‐Rocha et al ., ). Most tropical harvestman species have very poor dispersal capability (Mestre & Pinto‐da‐Rocha, ; Bragagnolo et al ., ), which results in a high degree of endemism (97.5% of the AF's harvestman are endemic; Pinto‐da‐Rocha et al ., ). The latter can be very informative in biogeographic studies, since the distribution of species that are poor dispersers carries a strong historical signal (Graham et al ., ; Cavender‐Bares et al ., ).…”

Species differences and geographic variation in the communal roosting behavior ofPrionostemmaharvestmen in Central American rainforests

“…Roosting behavior (Mestre & Pinto-da-Rocha 2004;Willemart & Gnaspini 2004), sex ratios (Chelini et al 2012), and mite infestation levels (Townsend et al 2006) are all known to vary seasonally in harvestmen, so it cannot be assumed that the species differences that we observed hold year round. With that caveat, the preferred roosting microhabitats of the two Prionostemma species at Refugio Bartola during the dry season could scarcely be more distinct.…”

“…Because harvestmen can live for years as adults (Gnaspini 2007), we did not pool data from repeated visits to the same sites and instead analyzed data from different months and seasons separately. In the case of the study of Mestre and Pinto-da- Rocha (2004), we chose one month per season that best represented the average sex ratio of all the months in that season. In the case of the study of Willemart and Gnaspini (2004), we pooled data from different aggregation sites but analyzed each collection date (Proud et al 2010) at La Selva, Costa Rica (E, F) in both shape and proportion.…”