Sutorius vellingae Vadthanarat, Raspé and Lumyong.
Pileus 7–5.1 cm, convex, margin slightly exceeding (1 mm); surface even to subrugulose, dark brown (8F6–7) with some purple (10F7) shining through at places; pileus context 12–13 mm thick halfway to the margin, yellowish white (2A2), with scattered small groups of reddish brown (9E/D7–8) encrustations. Stipe central, curved, cylindrical to slightly compressed, 6.8 _ 1.6 cm; surface even to finely scabrous, with some veins on the upper part, dull to slightly shiny, reddish gray to grayish brown (9C2–3), scattered with reddish brown (10F8) granulose squamules to purplish dark brown (9–10F4–6) granulose squamules near the base; basal tomentum little developed, yellowish white; stipe context solid, marmorate to virgate, yellowish white (2–3A2) and brownish red (10E6–7) to violet brown (10F6–7), with scattered small groups of reddish brown (9E/D7–8) encrustations. Hymenophore tubulose, adnate; tubes pinkish white (9A2), 7 mm long halfway to the margin; pores fine, subregular, violet brown (10F8). Odor fungoid. Taste not distinctive. Spore print not observed. Basidiospores (9–) 9.5–10.4–11.1 (–11.5) _ (3.6–) 3.8–4.2–4.6(–4.8) mm, Q = (2.22–) 2.22–2.52–2.82 (–2.93), N = 65, narrowly ellipsoid to subcylindrical with slight suprahilar depression, thinwalled, smooth, brownish to yellowish hyaline in water, yellowish hyaline in KOH or NH4OH, inamyloid. Basidia 4-spored (19–)19–24–28 (–28) _ (10–) 10–11–12 (–12) mm, with sterigmata up to 4.5 mm long clavate, hyaline, inamyloid. Cheilocystidia 28–29 _ 5–8 mm, rare, narrowly fusiform to fusiform, thin-walled, hyaline. Pleurocystidia 29–35 _ 6–7 mm, rare, narrowly fusiform to fusiform, thin-walled, hyaline. H. trama divergent, 36–77 mm wide, with 10–31 mmwide of subregular mediostratum. Pileipellis a trichoderm, 110–140 mm thick, thin-walled hyphae, composed of cylindrical terminal cells 23–61 _ 4–7 mm, with subacute to acute apex, slightly yellowish hyaline in water, slightly greenish to yellowish hyaline in KOH or NH4OH, with scattered yellowishbrown parietal encrustations. Pileus context made of moderately interwoven hyaline hyphae, 4–10 mm wide, with scattered reddish brown loose crystals in water or NH4OH. Stipitipellis a disrupted hymeniderm, 130–175 mm thick, composed of parallel hyaline hyphae anastomosing at places and terminal cells 13–19 _ 7–8 mm, thin-walled, giving rise to clusters of basidiole-like cells and caulocystidia, with scattered loose crystals. Caulocystidia (17–) 17–21–30 (–30) _ (7–) 7–9–11 (–11) mm, frequent in groups, fusiform to broadly fusiform, thin-walled, hyaline. Stipe context composed of parallel 4.5- to 9-mm-wide hyphae, with scattered loose crystals. Clamp connections not seen in any tissue. (Fig. 2 L, Fig. 2)
Habitat: Solitary under Castanopsis and Lithocarpus trees.
Distribution: Chiang Mai Province, Northern Thailand.
Notes: The Sutorius specimen voucher ECV3603 was first recognized as a taxon discrete from S. eximius and S. australiensis in the original publication of Sutorius, based on phylogenetic analysis of a combined LSU C tef 1 dataset (Halling et al.,2012). However, it was not described as a new species at that time because of the solitary nature of the collection. In this study, that same specimen was further studied and is hypothesized to be a new species, S. vellingae. Based on that single collection, S. vellingae is characterized by the combination of following characteristics: marked violet brown pore color; pileipellis trichoderm composed of cylindrical terminal cells with subacute to acute apex; rare, narrowly fusiform to fusiform cheilocystidia and pleurocystidia; and its very distinct, isolated
phylogenetic position within Sutorius.
Fig. 1 Phylogenetic tree inferred from the three-gene dataset (atp6, rpb2 and tef1), of Sutorius species and selected Boletaceae in Pulveroboletus group, using Maximum Likelihood and Bayesian Inference methods (ML bipartition tree is presented). The three Butyriboletus species were used as outgroup. All generic clades, excluding Sutorius, that were highly supported were collapsed. Seventeen species-level clades within Sutorius are indicated with label. Bootstrap support values (BS 70%) and posterior probabilities (PP 0.90) are shown above the supported branches. The star (*) indicates additional collections with exactly identical sequences or sequences differing only by heteromorphisms in tef1 (with the number of heteromorphisms mentioned in square brackets. (Phylogenetic tree from Vadthanarat et al 2021)