Pseudosperma triaciculare Saba & Khalid, 2020

Saba, Malka, Haelewaters, Danny, Pfister, Donald H. & Khalid, Abdul Nasir, 2020, New species of Pseudosperma (Agaricales, Inocybaceae) from Pakistan revealed by morphology and multi-locus phylogenetic reconstruction, MycoKeys 69, pp. 1-31 : 1

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.

Figures

Figure 1. The best-scoring ML tree (- lnL = 27210.474) of the Rimosae s. s. and Inosperma clades, reconstructed from the concatenated ITS-nrLSU-mtSSU dataset. ML bootstraps (if ≥ 70) are presented above or in front of the branch leading to each node. Thick branches have maximum support (ML BS = 100). Subclade designations within sect. Rimosae s. s. follow Larsson et al. (2009) in the strict sense. Newly-described species are in boldface.

Figure 3. The best-scoring ML tree (- lnL = 5704.951) of Rimosae s. s. subclade A, complemented with recently-described species within sect. Rimosae s. s., reconstructed from the nrLSU dataset. ML bootstraps (if ≥ 70) are presented above or in front of the branch leading to each node. Thick branches have maximum support (ML BS = 100). Newly-described species are in boldface.

Figure 6. Pseudosperma triaciculare: A Basidiomata of paratype collection (FH 00304561) B-F microscopic characters: B Basidia C cheilocystidia D caulocystidia E basidiospores F pileipellis. Scale bars: 1 cm (A), 10 µm (B, E), 30 µm (C, D, F).