Phylum:Basidiomycota >> Class: Basidiomycetes >>  Order: Boletales 
   
 
 BCRC Number NO BCRC Number!  
   
 Scientific Name: Austroboletus dictyotus
 
   
   
 Author:

Austroboletus dictyotus (Boedijn)Corner, Boletus in Malaysia p.80 –81. 1972.

Basionym: Porphyrellus dictyotus Boedijn, Persoonia 1: 316. 1960.

   
 
 
 
 
 Description: Pileus 5-7 cm broad, conical, then convex and umbonate when age, floccoso-felted to subsquamulose, whitish then pale fawn, at centre especially. Surface of the pileus covered by a thick pile about I mm high, composed of long sparingly branched, cylindric hyphae 4-9 um wide, long-celled, often arising from shorter wider cells 18 um wide in the tissue adjoining the flesh of the pileus. Context whitish, spongy, 8 - 10 mm thick in the centre of the pileus, unchanging when cut. Tubes 7 – 9 mm long, strongly sinuate decurrent, decurrent diminishing in length near the stipe and the margin whitish then vinaceous pink or pale vinaceous cinnamon. Pores 0.8 – 1 mm wide, circular, concolorous with tubes. Stipe cylindrical 5.5-6 cm long,14-16 mm broad, alveolate-lacunose, the alveolar 3-9 mm long, dirty yellow, about Chamois ( R).Spore print deep rufous madder to light chocolate. Spores 23 – 28 × 11 – 12.5 um, amygdaliform , exosporium ornamented coarsely tuberculate, 1.5 – 2 um deep, the ends pitting and pale, apiculus 0.3 um. Basidia clavate, 4-spored, 40-50 × 18-22.5 um; sterigmata conical, 7-8 um long, 1-2 um broad at the base, some with yellow content in KOH and Melzer,s. Pleurocystidia 71 – 132 × 20 – 26 um, mostly fusoid-ventricose, the apical half often elongation with one or two septa, 36-61 um long, and the apex subacute. Cheilocystidia rare, size and shape similar to pleurocystidia. Caulohymenium present over the whole stipe mainly consisting of basidioliform cells that are intermixed with both basidia and polymorphic, cystidia–like elements, extra- and intracellular pigments in 3 % KOH vivid orange, brown to ochraceous in the lower part of the stipe, pale yellowish above. Clamp connections absent.
 
 
 
 
 
 Specimens:

Taiwan, Nantou: Shanlihsi, alt. 1750m, 23 Nov. 1998, Chen CM 2303.

 
 
 
 Habitat: Solitary in the broad-leaved forest.
 
 
 
 Distribution:

Taiwan, Malaysia, Indonesia.

 
 
 
 References:

Zang, M et al. 1999.

   
   
   
 Provided:

C. M. Chen

 
 
 Note: Corner (1972) substituted subgen. Austroboletus for sect. Graciles (Singer) that was classified to genus Porphyrellus previously. Nevertheless Austroboletus resembles Strobilomyces in spore, Boletellus in pileus, and Heimiella in tube-trama. Thus Wolf (1979) proposed genus Austroboletus, based on the result of EM scanning observation. Its fruit bodies have a well developed marginal veil, a long lacunose-reticulate stem and boletoid tube-trama. Its spores are vinaceous pink to purple brown or chocolate in the mass; they are fusiform-amygdaloid and show a certain amount of compresion. They have a hyaline exospore and coloured endospore with conical warts or a close reticulation, apiculus 0.3-0.5 um long. Corner (1972) has explained that smooth boletoid spore has evolved from the ornamented one and Austroboletus is a transition between the twos. In our specimen examined, this collection can be easily distinguished from A. gracilis and A. subvirens reported before (Chen et al., 1997) by the white color of pileus. In addition, there are major differences in basidiospore morphology among them. Basidiospores of A. dictyotus are reticulate – ruminate medial surface, foveate proximal and distal surface. While those of A. gracilis have a verrucose – foveate surface thoroughly, some of which are easily lost and we found it difficult to find ornamented spores. Basidiospores of A subvirens with wall becoming minutely pitted, eventually dissected by meandering subreticulate channels that occasionally isolate irregular truncate warts or ridges, especially around middle, with walls up to 1.4 um thick. However, the acute distal end of the spores of A. dictyotus and the blunt distal end of the spores of A. subvirens can make it remarkable.