On the Brazilian Amazonian species of Acanthoscurria ( Araneae : Theraphosidae )

In this study the Brazilian Amazonian species of Acanthoscurria Ausserer, 1871 are redescribed: A. geniculata (C.L. Koch, 1841), A. tarda Pocock, 1903, A. juruenicola Mello-Leitão, 1923, A. theraphosoides (Doleschall, 1871). Acanthoscurria simoensi Vol, 2000 and A. insubtilis Simon, 1892, previously known from French Guyana and Bolivia, respectively, are recorded for Brazil by the first time. The females of these two species are described for the first time and a new species, A. belterrensis sp. nov., is described from Belterra, Pará, Brazil. In addition, four synonymies are established: A. transamazonica Piza, 1972 as junior synonym of A. geniculata; A. ferina Simon, 1892 and A. brocklehursti F.O.P.-Cambridge, 1896 of A. theraphosoides; and A. xinguensis Timotheo da Costa, 1960 of A. juruenicola. Acanthoscurria belterrensis sp. nov. resembles A. gomesiana Mello-Leitão, 1923 by the color pattern and structure of sexual organs. The male can be distinguished by the less curved embolus and the very projected prolateral superior and prolateral inferior keels, giving a triangular aspect to the basis of embolus, and the female seminal receptacles presenting a larger and narrower basis.

Variation.Some males lack vertical leg stripes.Male palpal bulb with accessory keel varying from vestigial to very evident and projected, sometimes bifurcated .
Natural history.The species is mainly nocturnal but in reproductive periods males can be found during the day, walking in the forest litter and crossing roads as other species of the genus (PÉREZ-MILES et al. 2005, GONZALEZ-FILHO et al. 2012).Females and juveniles dwell in tubular burrows, located under rocks, fallen trunks, inside living trees and in ravines and on the ground level.The burrow of a female in Rondônia was 18 cm wide and about 100 cm deep, with the entrance followed by a gradual decline, leading to a horizontal large chamber.
Male palpal bulb with long and thickened embolus ending like a shell with well developed superior and inferior keels and a third accessory one between them .
Synonymy.The examination of the holotype of A. xinguensis, specimens of A. juruenicola from Instituto Butantan and the specimen of A. juruenicola described by LUCAS et al. (1981) allowed us to consider A. xinguensis as a junior synonym of A. juruenicola, as all specimens shared the same morphology of male palpal bulb, tibial apophysis, blunt tubercle on palpal tibia and color.
Natural history.TIMOTHEO-DA-COSTA (1960: 1) states that three males and one large female were collected in an expedition to Alto Xingú, Mato Grosso, by the naturalist R. Arlé.An eggsac was also collected, approximately 5.5 cm wide and 1.5 cm high, containing about 3,944 young at various stages of development (TIMOTHEO-DA-COSTA 1960, figs 5-10).These spiders are aggressive, bite and easily throw urticating setae when disturbed.They can also display defensive behavior by raising the anterior legs, palps and opening the chelicerae, thus exposing the red ventral setae; at this moment the spiders open the fangs, releasing poison droplets in some cases, and make false attacks (mainly males), like A. suina (PÉREZ-MILES et al. 2005) and A. gomesiana Mello-Leitão, 1923(GONZALEZ-FILHO et al. 2012).Diagnosis.Acanthoscurria simoensi resembles A. geniculata and A. juruenicola by the structure of sexual organs, but differs by the male palpal bulb without an accessory keel and with a longer and smaller embolus, with the PS and PI projected , and by the female seminal receptacles with rectangular bases and two lobes projected apically and fused basally .
Synonymy.Acanthoscurria ferina and A. brocklehursti are herein considered junior synonyms of A. theraphosoides.The synonymies were established through the examination of the male holotype of A. theraphosoides, male holotype and female allotype of A. ferina, female holotype of A. brocklehursti and descriptions and illustrations given by SCHIAPELLI & GERSCHMAN DE PIKELIN (1964) of the male holotype and female allotype of A. ferina, corroborated by the study of several specimens from the different collections examined.The specimens examined present the same morphology of sexual organs, male palpal bulb and tibial apophysis and female seminal receptacles.They also share the same color pattern.
Natural history.This species can dig tubular burrows located under fallen trunks and in ravines.The tubular burrows have a circular shape, 3-4 cm wide and 10 to 20 cm deep.Males were collected walking in the forest litter and on roads near the forest and urban areas in Abunã, Porto Velho, Rondônia.Diagnosis.Acanthoscurria insubtilis resembles A. theraphosoides by the structure of sexual organs and body length (33.3-42.2mm), but it can be distinguished by a dark patch on ventral side of abdomen (Fig. 40), male palpal bulb with SGA not pronounced and less curved embolus; PS projected and fused to embolus .Female seminal receptacles divergent, originating from a wide U-shaped base .
Variation.The carapace color of live females and juveniles can be light brown to dark brown and the abdomen light pinkish-brown to dark pinkish-brown .