Sarcodon atroviridis sensu lato , a stipitate hydnoid from Amazonian campinarana , Roraima , Brazil

Sarcodon atroviridis sensu lato has a rich nomenclatural history as a result of its variable morphology. Here we discuss the species most plastic morphological characters as well as its ecology and distribution, and we report it for the first time from the State of Roraima, Brazil. Color images of the basidiomata, complete descriptions and microscopic images are also provided.

Sarcodon atroviridis (Morgan) Banker has a rich nomenclatural history.Described originally from North American material by Morgan (1895) as Hydnum L., the genus was changed to Sarcodon by Banker (1906).Subsequently, Peck (1906) described H. blackfordae Peck, which was also transferred to Sarcodon by Banker (1906).Baker and Dale (1951) described Hydnum bambusinum (R.E.D. Baker & W.T. Dale) Maas Geest.from Trinidad.More recently, Baird and Khan (1986) listed all names cited above as synonyms of Sarcodon atroviridis (Baird et al. 2013).In South America, Bononi (1981) reported this species as occurring in Bolivia, Trinidad and Tobago and Brazil from the states of Mato Grosso, Rio de Janeiro, São Paulo and Rio Grande do Sul.Singer et al. (1983) considered Sarcodon atroviridis as "rather variable in shape and color and usually somewhat darker than described with an ample area of distribution in the Americas, in the Amazonas region where it seems to be restricted to ectotrofic forests (campina and campinarana forest) and seems to form ectomycorrhiza with leguminous trees." Here we report Sarcodon atroviridis sensu lato in the Amazonian basin, from the state of Roraima, and we discuss the morphology and distribution of this species in its wide sense.
The description of the macroscopic features is based on fresh material.Microscopic-features description is based on dried specimens, rehydrated in water or 3% KOH for spore dimensions, and then mounted in Congo red to observe the hymenium and pileipellis, and in water for pigment localization.Twenty-five spores were measured including tubercles.Extreme measurements are indicated within parentheses.The following abbreviations are used: L (W) = average length (width) with standard deviation of the basidiospores measured; Q = spore quotient (length/width ratio); Qm = average spore quotient (Wartchow 2012).References to color codes follow Online Auction Color ( 2004) -OAC and Kuppers (1979).
Materials for scanning electron microscope (SEM) were dried and metalized with gold and observed at LEO 435VP with SE1 detector, EHT of 15-20 kV.(Morgan) Banker, Mem. Torrey Bot. Club 12: 148. 1906 N80C30A60) and olive green (OAC866 or N99C00A00) when dried, margin plane; context soft.Hymenium spinose, with spines up to 2 mm long and less than 0.5 mm wide, obtuse, very crowded about 9 spines per 1 mm 2 , adnexed, black in fresh material, white granules around the spines at stereomicroscope (25 ×; Figure 1B), and becoming brownish in dried state.Stipe 25 mm long and up to 4 mm wide, central, cylindrical black (between OAC 901-908 or N80C30A60) then olive green (OAC866 or N99C00A00) when dried, concolorous with the pileus, smooth and glabrous, context the same color of pileus.Spore print brown (OAC841).
Known distribution: USA, Trinidad and Tobago, Bolivia and Brazil (Amazonas, São Paulo, Rio de Janeiro, Paraná, Santa Catarina, Rio Grande do Sul and now Roraima).
Pileus up to 17 mm in diam., broadly convex; surface smooth, black colored (between OAC 901-908 or  Sarcodon atroviridis sensu lato (including our material) were referred as growing on soil.
In South America, a description of Sarcodon atroviridis sensu lato was given by de Meijer and Baird (1992) from Paraná state, South Brazil.They also reported it growing on soil, but with dark violet and purplish tints, a longer stipe up to 100 mm, mostly cylindric to subcylindric in form, and no evidence of olivaceous color after dried.Recently Magnago et al. (2015) also reported somewhat similar specimens of Santa Catarina and Rio Grande do Sul, South Brazil.Baird et al. (2013) considered now S. fumosus a synomym of S. scabripes despite the presence of clamps and subtle olive green color change in the context of S. fumosusis.This decision is supported by spore measurements, context color and other morphological characters described in the note provided by K.A. Harrison after reviewing collection MICH 10272 (Baird et al. 2013).
At the moment, we consider our collection to be 'Sarcodon atroviridis sensu lato', mostly due to the habit on soil and distribution in tropical South America (Figure 3), rather than on wood as occurring with the North American taxon.Phylogenetic studies with these taxa will be necessary for future clarification of the species concept within this group.

Figure 3 .
Figure 3. Geographical distribution of Sarcodon atroviridis.A: The shade areas represent previous reports from literature.B: Distribution in Brazil (yellow) and the new site of collection (green).