Two new tiny Nemesiidae species from Reserva Biológica do Tinguá , Rio de Janeiro , Brazil ( Araneae : Mygalomorphae )

Two new Nemesiidae species from Reserva Biológica do Tinguá, Rio de Janeiro, Brazil are described. Acanthogonatus minimus sp. nov. differs from the remaining species of the genus by the male palpal bulb, which has very long and twisted embolus, ca. 2/3 the length of the palpal tibia, long and twisted spermathecae, anterior eye row recurved and fovea T-shaped. Chaco tingua sp. nov. differs from the remaining species of the genus by the retrolateral megaspine on tibia I, palpal embolus tip hook-shaped, inferior tarsal claw on all legs, absence of pubescence on the carapace and legs. Both species were collected with Winkler extractors in leaf litter. They are the smallest specimens in their respective genera and also among the world Nemesiidae described to date. The smallest male of A. minimus sp. nov. measures 4.22 mm and of C. tingua sp. nov. measures 3.85 mm. Data on the phenology of C. tingua sp. nov. is presented.

Acanthogonatus was established by KARSCH (1880), with the type species, A. francki Karsch, 1880, based on a female from Chile.The genus currently includes 28 species, distributed mostly in the Occidental portion of South America, mainly in Chile and Argentina, and includes 25 species (GOLOBOFF 1995).In the Oriental portion, only A. ericae Indicatti et al., 2008 andA. tacuariensis (Pérez-Miles &Capocasale, 1982) are recorded, both in southern Brazil and the second also in Uruguay (PÉREZ-MILES & CAPOCASALE 1982, GOLOBOFF 1995, INDICATTI et al. 2008).
Chaco was established by TULLGREN (1905), with the type species, C. obscura Tullgren, 1905, based on a male from Salta, Argentina.The genus currently includes 11 species, six from Argentina, two from Chile, two from Uruguay and one from Brazil (GOLOBOFF 1995, MONTES DE OCA & PÉREZ-MILES 2013, FERRETTI 2014).
In an inventory using Winkler extractors in leaf litter in the Reserva Biológica do Tinguá, Rio de Janeiro, Brazil, representatives of two new Nemesiidae species were collected and are herein described: Acanthogonatus minimus sp.nov.and Chaco tingua sp.nov.In addition, data on the phenology of C. tingua sp.nov. is provided.

MATERIAL AND METHODS
The material examined is deposited in the following institutions (abbreviation and curator in parentheses): Instituto  1 A-C).
Samples were collected in the middle of each of the four seasons of 2002: summer (February 02-04); autumn (May 15-17); winter (June 05-07); spring (October 20-22).During each field excursion 25 points were marked along a 1,200 m transect, and at each point we stretched two perpendicular, 25 m lines; one to the left and the other one to the right.At the end of each line we delimited a 1 m 2 plot, totaling 50 plots.Each sample refers to one square meter of leaf litter, which was removed and sieved in a 5 mm mesh and soon after placed into the Winkler extractor where it remained for 48 hours.This procedure was adapted from DELABIE et al. (2000) and ORSOLON-SOUZA et al. (2011).Since abundance data did not meet the assumptions of parametric tests, the Kruskal-Wallis (KW) nonparametric analysis of variance was used for detecting betweenseasons differences in abundance of males, females and juveniles separately (ZAR 1999).
Etymology.The specific name is a noun in apposition taken from the type locality.63, which shows that the main activity period of males was during the winter (seven individuals), decreasing in the spring (three individuals).These values are statistically significant when the seasons are compared (KW = 9.173, GL = 3, p = 0.0270).However, the data obtained on male abundance are are not conclusive since the sample size is small.During the winter the lowest mean temperature and precipitation were recorded during the sampling period (Fig. 64), showing that the winter is probably the mating period of C. tingua sp.nov.If the same parameter is observed among females, an increase in the abundance curve is detected, but without clear activity peaks.A slight increase in activity was observed in the spring, when 22 females were collected, and during the summer, when 16 specimens were collected; these differences, however, are not statistically significance.Our dataset does not show clear activity peaks for females of C. tingua sp.nov., but there was a small and yet noticeable increase in activity in the spring and summer, when temperatures and precipitation were higher (Fig. 64).During field captures in the autumn we observed a lack of males and a smaller number of females (N = 6) of C. tingua sp.nov.Juvenile specimens were numerous in samples from the four seasons, with significance values (KW = 10.902,GL = 3, p = 0.0122).We suggest that the autumn is the growing period, because newly born Nemesiidae spiders were found forming assemblages in the litter, making their detection easier using the Winkler extractor.

Ecological data
Another observation we have made while looking at the samples obtained with the Winkler extractor is the massive presence of females, five times greater than the number of males.This pattern could be explained by the selectivity of the Winkler trap compared with pitfall traps.The first favors the capture of spiders at an area of a square meter, whereas soil traps such as pitfall traps capture wandering spiders ( Male of A. alegre Goloboff, 1995, A. brunneus (Nicolet, 1849), A. incursus (Chamberlin, 1916), A. juncal Goloboff, 1995, A. mulchen Goloboff, 1995, A. parana Goloboff, 1995, A. peniasco Goloboff, 1995, A. tolhuaca Goloboff, 1995 and A. vilches Goloboff, 1995 are unknown.1.ITC IV absent .. A. huaquen Goloboff, 1995 3'.Bulb different .
ZOOLOGIA 32 (2): 123-138, April 2015 mately eight hours.After dehydration it was critical-point dried.All the material used in SEM was fixed to stubs with doublefaced adhesive copper tape and sputter-coated with gold.Images were taken under high vacuum with a FEI Quanta 250 SEM at the Instituto Butantan.Pictures were

Acanthogonatus minimus sp. nov. and Chaco tingua sp. nov.
Were recorded 22 individuals of A. minimus sp.nov., three males (registered in summer), 11 females (seven in the spring collections) and eight juveniles.Since we only collected a few specimens of A. minimus sp.nov. it is not possible to draw conclusions on the fenology of the species, but that is sufficient data to compare it with what we know about other species of the genus.We observed that male and female specimens of Acanthogonatus ericae Indicatti et al., 2008 were collected with pitfall traps in the winter and the spring of southernBrazil  (INDICATTI et al. 2008).In another study using pitfall traps (FERRETTI etal.2012),males of Acanthogonatus centralis Goloboff, 1995 were recorded when temperatures were medium or low (autumn, end of winter and spring), while females and juveniles were collected when temperatures were high or low (summer and winter).Contrasting with A. minimus, C. tingua sp.nov.was abundant in the samples, totaling 12 adult males (2.89%), 59 females (14.2%) and 343 juveniles (83.5%).The phenology of C. tingua sp.nov. is illustrated in Fig.