Micropsalliota ventricocystidiata Al-Sadi & S. Hussain 2022, sp. nov.
Creators: name: Al-Kharousi, Moza
name: Hussain, Shah
name: Al-Muharabi, Marwa A.
name: Al-Maqbali, Dua'A
name: Al-Shabibi, Zahra
name: Al-Balushi, Abdullah H.
name: Al-Yahya'Ei, Mohamed N.
name: Saady, Nadiya Al
name: Velazhahan, Rethinasamy
name: Al-Sadi, Abdullah M.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Fungi
Basidiomycota
Agaricomycetes
Agaricales
Agaricaceae
Micropsalliota
Micropsalliota ventricocystidiata

description: Micropsalliota ventricocystidiata Al-Sadi & S. Hussain, sp. nov. (Figs. 3, 4)
MycoBank no: MB842602
Diagnosis: Micropsalliota ventricocystidiata can be distinguished from other species by its: medium-sized basidiomata with hemispheric pileus, covered with reddish-brown squamules, basidiospores amygdaliform to oblong, measuring 7.5–8.5 × 4.5–5.0 µm, with ventricose cheilocystidia.
Etymology: The specific epithet “ ventricocystidiata ” refers to the ventricose shape of the cheilocystidia of the new species.
Type: Oman, Dhofar, Gogob, 17°18′28.9″ N and 54°06′27.6″ E under the trees of Anogeissus dhofarica, 2 Sept 2018, N. Al Dhanki, S. Al Salami, M. Al Jahwari and I. Al Sabahi, GOB-002 (holotype SQUH-GOB002; GenBank accession: ITS = OM 397374, 28 S = OM 630413).
Description:Pileus 30–55 mm diam, at young stage ovoid to parabolic, as the pileus opened becoming hemispheric, at mature stage convex to plano-convex; surface finely squamulose, squamules more or less triangular or granular, slightly erect, concentrated at the center, sparse towards the margin, light reddish-brown (2.5YR 5/4–2.5YR 6/4) to moderate reddish-brown (7.5R 3/4–7.5R 3/6) on a white background; margins slightly scalloped. Lamellae free, crowded (25–30 per centimeter), ventricose, reddish-gray (7.5YR 6/2), with 1–5 series of lamellulae, becoming lightbrown (5YR 6/4) with age. Stipe 40–70 × 7–10 mm, central, equal, hollow, surface granulose, granules white, sparce above the annulus, more concentrated below the annulus, on a white background; annulus single layered, membranous, ascendant, white, smooth on both surfaces. Context white, unchanged on handling. KOH reaction reddish-brown on pileus. Odor and taste not recorded.
Basidiospores [60/2/2] (7.0)7.5–8.5(9.0) × (4.0)4.5–5.0(5.5) µm, on average 8.2 × 4.8 µm, Q = 1.6–1.86, av. Q = 1.7, ellipsoid to amygdaliform with acute apex in side view, oblong to sub-cylindrical in frontal view, smooth, brownish in 5% KOH, germ-pore absent. Basidia 20–26 × 8–9.5 µm, clavate, hyaline, smooth, 4-spored. Cheilocystidia 36–46 × 9.5–16 µm, mostly ventricose, rarely sub-cylindrical, abundant, smooth, hyaline. Pleurocystidia absent. Pileus covering is a cutis with septate hyphae, 10–15 µm diam, rarely branched, terminal cells 51–67 × 10–12 µm with acute apex, pale brownish in KOH. Clamp connections absent.
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Habitat and distribution: Scattered in small groups, saprotrophic, on humus rich soil with dead leaves and wood under the trees of Anogeissus dhofarica. So far only known from southern Oman.
Additional specimens examined: Oman, Dhofar, Attir, on a shady place with plenty of liverworts, 5 Sept 2018, N. Al Dhanki, S. Al Salami, M. Al Jahwari and I. Al Sabahi, ATR-004 (SQUH-ATR004; GenBank accession: ITS = OM 397373, 28 S = OM 630414).
Notes: The new species Micropsalliota ventricocystidiata is characterized by a medium-sized basidiomata with hemispheric to plano-convex pileus, covered with reddish-brown squamules; basidiospores amygdaliform with obtuse apex in side view, oblong in face view, measuring 7.5–8.5 × 4.5–5.0 µm and the cheilocystidia mostly ventricose, rarely more or less subcylindrical.
ML phylogenetic analyses revealed that the closely related species of M. ventricocystidiata are: M. suthepensis, M. megaspora, M. repanda and M. sp. (SDJ 2021-8-9) an undescribed species from China.
Micropsalliota suthepensis, described from Thailand, differs from M. ventricocystidiata by (i) its smaller pileus (10–20 mm diam) with violet squamules (ii) smaller spores (5–6 × 3–3.5 µm) that are somewhat similar in shape and have apical thickening, and (iii) cheilocystidia clavate with non-capitate apex (Zhao et al. 2010). Micropsalliota megaspora, also described from Thailand, differs in its small sized basidiomata, smaller spores (5.2–6.5 × 3.4–4 µm) and pyriform shaped cheilocystidia (Zhao et al. 2010). Micropsalliota repanda, originally described from Togo, differs from the new species by its pinkish pileal fibrils with clavate cheilocystidia (Heinemann 1980). Morphological comparison of the new species with regards to other species of Micropsalliota are further sorted in detail in Table 2.
Morphologically, the new species M. ventricocystidiata is similar to M. digitatocystis R.L. Zhao, J.X. Li & M.Q. He (2021: 171), a recently described species from China (Li et al. 2021). Both species share the reddish-brown pileal squamules. On the basis of basidiospores morphology, both species can be differentiated. Basidiospores in M. digitatocystis are mostly ellipsoid to amygdaliform and comparatively smaller (5.8–7.4 × 4–4.6 µm; Li et al. 2021). In M. ventricocystidiata, basidiospores are amygdaliform with obtuse apex to sub cylindrical or oblong and larger (7.5–8.5 × 4.5–5.0 µm). In M. digitatocystis cheilocystidia are cylindrical to subclavate, subcapitate to capitate, measuring 37.4–52 × 9–16.4 µm. On the other hand, cheilocystidia in M. ventricocystidiata are mostly ventricose, rarely subcylindrical.
description: Published as part of Al-Kharousi, Moza, Hussain, Shah, Al-Muharabi, Marwa A., Al-Maqbali, Dua'A, Al-Shabibi, Zahra, Al-Balushi, Abdullah H., Al-Yahya'Ei, Mohamed N., Saady, Nadiya Al, Velazhahan, Rethinasamy & Al-Sadi, Abdullah M., 2022, Notes on the genus Micropsalliota (Agaricales, Basidiomycota) and the description of a new species from Southern Oman, pp. 113-126 in Phytotaxa 543 (2) on pages 119-123, DOI: 10.11646/phytotaxa.543.2.2, http://zenodo.org/record/6450745