Comparisons of species richness among assemblages using different sample sizes may produce erroneous conclusions due to the strong positive relationship between richness and sample size. A current way of handling the problem is to standardize sample sizes to the size of the smallest sample in the study. A major criticism about this approach is the loss of information contained in the larger samples. A potential way of solving the problem is to apply extrapolation techniques to smaller samples, and produce an estimated species richness expected to occur if sample size were increased to the same size of the largest sample. We evaluated the reliability of 11 potential extrapolation methods over a range of different data sets and magnitudes of extrapolation. The basic approach adopted in the evaluation process was a comparison between the observed richness in a sample and the estimated richness produced by estimators using a sub‐sample of the same sample. The Log‐Series estimator was the most robust for the range of data sets and sub‐sample sizes used, followed closely by Negative Binomial, SO‐J1, Logarithmic, Stout and Vandermeer, and Weibull estimators. When applied to a set of independently replicated samples from a species‐rich assemblage, 95% confidence intervals of estimates produced by the six best evaluated methods were comparable to those of observed richness in the samples. Performance of estimators tended to be better for species‐rich data sets rather than for those which contained few species. Good estimates were found when extrapolating up to 1.8‐2.0 times the size of the sample. We suggest that the use of the best evaluated methods within the range of indicated conditions provides a safe solution to the problem of losing information when standardizing different sample sizes to the size of the smallest sample.

We suggest a new phylogenetic hypothesis for the tripunctata radiation based on sequences of mitochondrial genes. Phylogenetic trees were reconstructed by parsimony, maximum likelihood and Bayesian methods. We performed tests for hypotheses of monophyly for taxonomic groups and other specific hypotheses. Results reject the monophyly for the tripunctata group whereas monophyly is not rejected for the tripunctata radiation and other specific groups within the radiation. Although most of the basal nodes were unresolved we were able to identify four clusters within the tripunctata radiation. These results suggest the collection of additional data before a proper taxonomic revision could be proposed.

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ABSTRACT. It was sampled the litter frogs at altitudinal sites of a semideciduous mesophytic forest located at SeITa do Japi (Jundiaí, São Paulo, 23°I7'S, 47°00'W, 800-1300m altitude, 1500mm rain/year). Forty two plots of 8x8m were sampled in the dly/cold season of 1995: 21 at a Higher Site (HS) (lOOOm) and 21 at a Lower Site (LS) (850m). The plots were evenly located near, mid-distance, and far from lhe stream-bed. lt was found a total of tive species, three aI each sile. Eleulherodaclylus guenlheri comprised 83% of lhe individuaIs aI HS and E. juipoca 67% aI LS. The density of individuaIs was higher aI HS and near lhe slream. The grealer density aI HS may be due to grealer humidity there, provided by mist. The frogs may aggregate in wetter places (stream edges) in lhe dry/cold season. The studied sites represent harsh and early successional environments and bolh these factors may be acting together to produce the low observed diversity. KEY WORDS. Brachycephalus, Eleutherodactylus, Hyla, litter frogs, diversity, Southeastern Brazil Species composition and abundance of litter frogs are influenced by local environmental conditions such litter depth and humidity (SCOTT 1976; TOFT 1980) in addition to historical factors such as human disturbance (LIEBERMAN 1986; HErNEN 1992). The Serra do Japi is a group of low mountains in the Mantiqueira range in Southeastern Brazil mostly covered by a seasonally dry semideciduous mesophytic forest (LEITÃO-FILHO & MORELLATO 1997). On its west face, in a 300m altitudinal range (850-1 170m), different vegetational types are found (RODRIGUES & SHEPHERD 1992). lt was sampled the litter frogs at two altitudinal sites on this west face, in the altitudinal extremes where an accessible forest stream is found. Specifically it was asked: I) Do lhe litter frog diversity and abundance differ between the sites?; and 2) Do the abundance vary with distance from the stream? Revta bras. Zool. 14 (2): 341 -346 ,1 997