Indoporus shoreae A. Parihar, K. Das, Hembrom & Vizzini, in Parihar et al., Cryptog. Mycol. 39(4): 453 (2018)
Etymology: ‘Shoreae’ refers to Shorea robusta (Dipterocarpaceae), the host tree
Pileus 10-45 mm diam., initially convex, then plano-convex; surface dry, squamulose, grey (19-20B1) with black squamules, becoming black slowly when bruised or with age; margin entire, encurved. Pileus surface ruby (12C-D8) to blackish red with KOH but unchanging with FeSO4. Pore surface depressed near the juncture of stipe with age, reddish grey (12B2) or paler when fresh, slowly becoming reddish grey (7B2) with maturity, becoming initially brownish orange (6C4) on bruising then brown (7E4-5) to dark violet (15F8) finally, black to charcoal black after 5 minutes but, turning violet brown (11E4-5) initially then black with KOH; pores 2-3 per mm angular, simple. Tubes adnate, 4-5 mm long, pinkish white to greyish red (8C4-5) becoming black on 5 minutes after exposure. Stipe 30-45 × 5-8 mm, cylindrical to clavate, becoming narrow towards base, smooth, reticulation absent, greyish violet (17D4) at upper half, then grey (18F1) to blackish brown, finally becoming black. Context up to 7 mm wide in pileus, yellowish white on exposure, quickly becoming dull red to greyish red (8B3-4) then greyish magenta (13E4) finally, black to charcoal black, turning reddish brown to brownish red (9- 10D8) with KOH, unchanging with FeSO4; stipe context in young basidiomata reddish white to reddish grey (9A2-9B2) in upper half, dark blackish brown on lower half while in mature basidiomata greyish violet to dark violet (18E-F5) in upper half and dark blackish brown on lower half, becoming black to charcoal black on exposure, but turning coffee brown then blackish with KOH. Spore print greyish brown (6D3).
Basidiospores 8.72-12.3-12.5-(18.4)-20 × 3.6-4.5-4.7-5.4 μm, (Q = 2.1- 2.65-2.72-3.5), cylindrical, subfusiform, inequilateral, thin-walled, smooth. Basidia 28-41 × 8-10 μm, four-spored, clavate. Pleurocystidia 29-38 × 12-17 μm, rare, emergent up to 20 μm, lanceolate to ventricose, thin-walled, hyaline. Subhymenial layer up to 10 μm thick, pseudoparenchymatous. Tube edge fertile with basidia and cystidia; cheilocystidia 28-37 × 8-9 μm, frequent, narrowly lanceolate with rounded to capitate apex, hyaline. Hymenophoral trama divergent, hyphae septate, up to 10 μm wide. Pileipellis a trichoderm, 250-350 μm thick, composed of erect to suberect, loosely interwoven unbranched to rarely branched hyphae, mostly with constriction at septa, moderately thick-walled with dark brown to blackish pigment, mostly smooth sometimes with zebroid incrustationss; terminal cells typically inflated, 10- 45 × 5-12 μm, cylindrical to subcylindrical, sometimes subfusoid, content brown pigmented. Stipitipellis up to 50 μm thick, fertile near the apex of stipe, composed of basidioles, basidia and cystidia in several clusters; caulobasidia 30-35 × 9-10 μm, 2- to 4-spored, clavate; caulocystidia 45-57 × 11-14 μm, frequent, ventricose, lanceolate to obclavate, hyaline.
Ecology: Solitary to gregarious on the soil in the dry deciduous forest under the Shorea tree; known from the Koderma Wildlife Sanctuary and Rajmahal hills of Indian state Jharkhand and Lalgarh block of another Indian state West Bengal.
Index fungorum number: IF828966
Notes: Phylogenetically Indoporus shoreae is a distinct lineage within the Boletaceae but its true relationships to other bolete genera remained unresolved. Morphologically, Indoporus is somewhat similar to Afroboletus Pegler & T.W.K. Young and Strobilomyces Berk. Both these genera share the squamulose pileal surface and similar hymenophoral surface with Indoporus, but their ornamented basidiospores clearly separate them from the new genus (Pegler & Young 1981, Gelardi et al. 2013). Porphyrellus E.-J. Gilbert and Nigroboletus Gelardi, Vizzini, E. Horak, T.H. Li & Ming Zhang also show partial resemblance to the present novel genus because of the colour of pileus and smooth basidiospores, but the former can be separated by its white to pallid context, and bluish or reddish discoloration when cut (Gilbert 1931; Wolfe 1979), in comparison to reddish grey context which turns reddish brown to charcoal black when cut in Indoporus. Nigroboletus can be separated by its smooth pinkish pileus, yellowish to pinkish-orange stipe and yellowish context, moreover it is found to grow in forests dominated by Fagaceae and coniferous trees (Gelardi et al. 2015). Tylopilus species can be distinguished (Chakraborty et al. 2018) by white to pallid context of the pileus, a hymenophoral (pore) surface white when young, and discoloring pinkish when mature (reddish grey or paler from very beginning in case of Indoporus). Two North American species, viz. Tylopilus alboater (Schweinitz) Murrill and T. atronicotianus, look quite similar to the novel species. However, both these Tylopilus species have robust basidiomata with a pileus 30-150 mm diam. and stipe 40-100 mm in T. alboater, and pileus 75-200 mm diam. and stipe 60-120 mm in T. atronicotianus (Bessette et al. 2010, 2016) as well as distinctively smaller basidiospores (8-12 × 3-4 µm in T. alboater and 7.5-10.5 × 4-5 µm in T. atronicotianus). Both these species are also genetically different. Further, Indoporus shoreae appears to be strictly associated with Shorea robusta in tropical broadleaf forests.
Figure 1. Phylogram generated from combined nrLSU and rpb2 sequences: The evolutionary history was inferred by using the Maximum Likelihood method. Bootstrap support values (>70%) obtained from the ML analysis are shown above or below the branches at nodes.
Figure 2. Phylogram generated from nrITS sequences: The evolutionary history was inferred by using the Maximum Likelihood method. Bootstrap support values (>70%) obtained from the ML analysis are shown above or below the branches at nodes.