Pseudosperma triaciculare Saba & Khalid sp. nov. Figure 6

Diagnosis.

Characterised by the acutely umbonate brownish-orange to fulvous pileus, the presence of a pale velipellis coating on the pileus, septate cheilocystidia and an ecological association with Pinus .

Types.

Holotype: Pakistan, Prov. Khyber Pakhtunkhwa, Mansehra, Batrasi, under Pinus roxburghii, 3 Aug 2014, leg. M. Saba & A.N. Khalid; MSM#0039 (LAH 310054); GenBank accession nos. MG742423 (ITS), MG742424 (nrLSU), MG742425 (mtSSU). Paratypes: ibid., 3 Aug 2014; MSM#0040 (LAH 310055); GenBank accession nos. MG742426 (ITS), MG742427 (nrLSU), MG742428 (mtSSU). Ibid., 3 Aug 2014; MSM#0041 (LAH 310056); GenBank accession nos. MG742429 (ITS), MG742430 (nrLSU), MG742431 (mtSSU). Pakistan, Prov. Khyber Pakhtunkhwa, Abbottabad, Shimla, 14 Sep 2012, leg. M. Saba & A.N. Khalid; MSM#0038 (FH 00304561).

Etymology.

From Latin, meaning “three-needled,” with reference to the association with the three-needled pine Pinus roxburghii .

Description.

Pileus 12-29 mm in diam., conical when young, plane to convex at maturity, with acute to subacute or obtuse umbo; margin radially rimose, straight or flaring to uplifted; surface dry, dull, colour brownish-orange (5YR5/8) to fulvous, presence of a pale velipellis coating over the disc. Lamellae regular, adnexed to sinuate, close, pale orange yellow (10YR8/4), edges even; two tiers of lamelullae. Stipe 19-60 mm, central, equal, fibrillose, white with pale orange yellow tinge (10YR8/4). Odour mild, not diagnostic.

Basidiospores (7.7-)8.9-12.5 × 6.1-7.7 µm [x = 10.2 × 6.9 µm, Q = 1.64-2.2], smooth, mostly elliptic, thin-walled, yellowish-brown in KOH, apiculus present small and indistinctive. Basidia 24-36 × (9-)10-13 µm, clavate to broadly clavate with refractive contents, 4-sterigmate, thin-walled, hyaline in KOH; sterigmata 2.5-4.0 µm long. Pleurocystidia absent. Cheilocystidia cylindrical to clavate, septate, some with sub-capitate apices, terminal cells 23-54 × 9-16 µm, non-encrusted, hyaline, thin-walled. Caulocystidia 36-98 × 7-14 µm, cylindrical, non-encrusted, hyphoid, thin-walled. Pileipellis a cutis, hyphae cylindrical, 6-12 µm wide, thin-walled, golden brown or yellowish-brown in KOH, without encrustations, septate. Lamellar trama of parallel hyphae, 6-12 µm wide; subhymenium of compact hyphae, 3-6 µm wide. Stipitipellis cylindrical hyphae, 2-12 µm wide, hyaline in mass in KOH; all structures inamyloid. Clamp connections present.

Habit and habitat.

Occurring in August to September, solitary or in groups, scattered on the forest floor in stands of Pinus roxburghii ( Pinaceae).

Notes.

Pseudosperma triaciculare has been found in association with Pinus roxburghii, the three-needled pine. This new species forms a distinct monophyletic group without clear affinities outside of Rimosae s.s. subclade A (Figures 1 - 3). Some of the unique features of this species are the umbonate brownish-orange to pale orange yellow pileus; cylindrical to clavate cheilocystidia; and cylindrical, non-encrusted, hyphoid caulocystidia. Allied species include P. brunneoumbonatum, P. griseorubidum (K.P.D. Latha & Manim.) Matheny & Esteve-Rav., P. keralense [synonym I. rimulosa C.K. Pradeep & Matheny] and P. umbrinellum . Pseudosperma triaciculare shares the same presumed Pinus association and shape of basidiomata with P. brunneoumbonatum, but can be distinguished by its brownish-orange pileus and smaller basidiospores. Pseudosperma umbrinellum is differentiated from P. triaciculare by the presence of an obtuse umbo (acute in P. triaciculare), yellowish- or reddish-brown pileus (brownish-orange in P. triaciculare), somewhat narrower basidiospores (5.5-6.5 µm vs. 6.1-7.7 µm) and a broad host range, including species in Cistaceae, Fagaceae, Pinaceae and Salicaceae (Larsson et al. 2009).

Pseudosperma triaciculare is most closely related to P. griseorubidum and P. keralense, described recently from tropical India (Latha and Manimohan 2015, Pradeep et al. 2016, Figure 3). Pseudosperma griseorubidum can be differentiated by its pileus, which is greyish-red and rarely with an umbo. In addition, P. griseorubidum is associated with members of Dipterocarpaceae (Latha and Manimohan 2015). The differences between P. keralense and P. triaciculare are more subtle. Pseudosperma keralense can be separated based on the following features: its lamellae have serrate edges and its basidiospores are narrower on average (6.1 vs. 6.9 µm in P. triaciculare). It is also phylogenetically clearly different; the ITS sequence of the holotype collection (GenBank acc. no. KM924523) is 84.11% identical to the holotype of P. triaciculare, whereas the LSU (KM924518) is 95.13% identical.

Other similar Asian species include P. himalayense, P. neoumbrinellum, P. pakistanense and P. yunnanense (T. Bau & Y.G. Fan) Matheny & Esteve-Rav. Pseudosperma triaciculare resembles P. neoumbrinellum in its pileus and basidiospores. However, it is easily differentiated by the characteristic brownish-orange to fulvous colouration of its pileus, whereas the pileus of P. neoumbrinellum is chocolate to dark brown in colour (Bau and Fan 2018). In addition, the shape and size of caulocystidia in these two species are very different: 20-48 × 10-17 µm in P. neoumbrinellum vs. 36-98 × 7-14 µm in P. triaciculare . Pseudosperma triaciculare is different from the recently-described P. himalayense from Pakistan (Liu et al. 2018) by the presence of a velipellis and a shorter stipe (16-60 vs. 50-80 µm). Pseudosperma pakistanense is separated from P. triaciculare by the absence of velipellar hyphae (unless the authors referred to the velipellis by their description of "[pileus] sometimes peeling off in the form of fine threads"), presence of pleurocystidia and a generally wider stipitipellis lacking caulocystidia (Ullah et al. 2018). Finally, P. yunnanense, described from China, also has velipellar hyphae, but its basidiomata are much larger in size (pileus 30-60 mm in diam., stipe 60-70 mm) and it lacks caulocystidia (Bau and Fan 2018). We did not include P. yunnanense in our phylogenetic analyses, but blasted the ITS sequence of the holotype collection (GenBank acc. no. MH047250) against P. triaciculare, resulting in 89.09% identity. Pseudosperma yunnanense is phylogenetically most similar to P. perlatum .

Finally, P. avellaneum, P. bisporum, P. macrospermum and P. transiens from Kobayashi’s (2002) morphological Inocybe treatment are all different from P. triaciculare . Of all four, P. avellaneum is probably most difficult to separate from the new species: its pileus is pale greyish-ochraceous, the stipe is less slender and - this seems the best character for separating both species - no caulocystidia were observed. Pseudosperma bisporum has lamellae with serrate edges, 2-sterigmate basidia and pileipellis hyphae that are smaller in diameter. In addition, again, no caulocystidia were observed in this species. Compared to P. triaciculare, the basidiospores of P. macrospermum are longer (10.5-)14.0-15.5(-18.3) vs. (7.7-)8.9-12.5) µm, its basidia are narrower (8.8-9.5(-12.5) vs. (9-)10-13 µm) and its cheilocystidia are wider (16-18 vs. 9-16 µm). Pseudosperma transiens has basidiospores (4.8-6.5 vs. 6.1-7.7 µm) and basidia (8.8-9.5 vs. (9-)10-13 µm) that are both narrower than those in P. triaciculare . In addition, the pileus of P. transiens is coloured brown to dark brown, whereas P. triaciculare has a brownish-orange to fulvous pileus.