Andrés Taucare-Ríos

Microhabitat selection in the sand recluse spider (Sicarius thomisoides): the effect of rock size and temperature

ABSTRACT In spiders, temperature is considered an important environmental variable for microhabitat selection. In this study, we evaluated the effect of temperature and rock size on the presence of the sand recluse spider Sicarius thomisoides and the degree of selectivity in different locations. This species is a large spider that lives under rocks in desert and semi-desert climates and is particularly active during the summer. In Chile, these spiders can be found at both coastal and inland locations under different thermal conditions, where usually the temperatures are lower near the coast. If large-scale climatic conditions are important for this species, they may be expected to select lower rock temperatures on the coast than at inland locations. In addition, we would expect that the spiders would choose larger rocks in inland compared to coast locations, which reduce the effect of high temperatures. We found that the probability of finding individuals of this species increased according to rock temperature and rock size in the field. Our results suggest that S. thomisoides prefers larger and warmer rocks to shelter under during the day, this selectivity being similar at both coastal and inland locations. Thus, this species tends to select rocks with the same thermal and structural conditions, independent of the climatic conditions.

Primeros registros de la araña saltarina Hasarius adansoni (Auodouin, 1826) (Araneae: Salticidae) en Chile

A partir de aranas adultas capturadas en la Region de Tarapaca se registra por primera vez para Chile la presencia de Hasarius adansoni Auodouin, arana cosmopolita frecuentemente presente en climas calidos. Se entrega una breve diagnosis para reconocer la especie y datos acerca de su distribucion e historia natural. Se discute respecto de las posibles vias de ingreso de este aracnido a Chile.

Occurrence of Philolema sp. (Hymenoptera: Eurytomidae) in Latrodectus thoracicus (Nicolet, 1849) (Araneae: Theridiidae) Egg Sacs

Abstract Aspects of the natural history of the black widow spider Latrodectus thoracicus (Nicolet, 1849) are poorly known. The first observation of predation on L. thoracicus egg sacs is presented here, and we describe the predatory wasp (Philolema sp.) as a natural enemy for this species.

Nuevos registros de arañas (Araneae: Arachnida) para la Región de Arica y Parinacota, Norte de Chile

A partir de aranas adultas colectadas en el valle de Azapa se actualiza el numero de especies presentes en la Region de Arica y Parinacota. Se entregan datos ecologicos y distribucionales de las especies encontradas y una breve diagnosis para poder identificarlas.