Ancylometes Bertkau

Höfer, H. & Brescovit, A. D., 2000, A revision of the Neotropical spider genus Ancylometes Bertkau (Araneae: Pisauridae), Insect Systematics & Evolution 31, pp. 323-360 : 354-356

[Genus Ancylometes Bertkau ]

Natural history

All observed Ancylometes species ( bogotensis, hewitsoni, riparius, rufus, terrenus) are nocturnal hunters and strongly ground related, however they climb on tree trunks to hide during inundation of the ground or to flee from army ants. During the day they hide in crevices and at night they hunt in a sit-and-wait manner, often near water bodies. The biology of A. rufus in a terra firme forest near Manaus (Reserva Ducke) was studied by Azevedo (1999). The species is most frequently observed along small rivers in the forest. An observed strong temporal variation of densities along the stream indicated seasonal migrations within the habitat, e.g. to the stream banks during the dry season and to small water ponds within the forest during the wet season.

Hunting on frogs has repeatedly been observed for several species ( Brandão pers. comm. for A. concolor - IBSP 6536, preying Hyla sp.; for A. rufus and A. hewitsoni pers. obs. and photo in Höfer & Beck 1996, photos in Bernarde et al. 1999, Hödl 1993); and tadpoles (pers. obs.) and fish (pers. obs.) are also preyed. The spiders can easily paddle on the water surface, and dive for prey but also to hide; remaining more than 30 minutes below water has been recorded (pers. obs.). One bite accident in Manaus has been brought to our knowledge, but in the field these spiders are not at all aggressive and can easily be captured by hand. Moults are often found hanging down from leaves in vegetation (30-50 cm above ground). One male which was kept for one night in a small device had difficulties to moult, which resulted in curved legs. Pompilid wasps have been observed to prey on Ancylometes spiders. To avoid flooding in inundation forests and army ant raids in terra firme forest the spiders climb on tree trunks, where they were caught in arboreal funnel traps.

Mating of A. bogotensis was described by Merrett (1988). We found some females with their epigynes plugged. Females carry their egg sacs, which are covered by strong brown water proof silk, attached to the chelicerae and held by the pedipalps under the venter. Egg sacs of A. rufus contained more than 1000 eggs. The nursery webs constructed by the females of A. rufus are about 10 cm in diameter and were frequently encountered near the ground along the stream. Juveniles were observed to remain for about one week in the webs. Adults were encountered throughout the year indicating that there is no seasonal reproduction(Azevedo 1999).