Candolleomyces asiaticus M. Asif, A. Izhar, Niazi & Khalid 2022, sp. nov.

Field: Agricultural and Biological Sciences (Life Sciences)

Candolleomyces asiaticus M.Asif, A.Izhar, Niazi & Khalid sp. nov. Mycobank: MB841351 Figs 2–3 Diagnosis Differs from Candolleomyces cacao by the combination of the following characters: broad spores (up to 6.3 µm) with indistinct germ pore, absence of caulocystidia, and whitish evanescent veil. Etymology The specific epithet ‘ asiaticus ’ refers to the continent from where it was collected. Type material Holotype PAKISTAN • Punjab Province, Haroonabad City, District Bahawalnagar; 29°60′81″ N, 73°14′67″ E; alt. 163 m a.s.l.; on nutrient-rich loamy soil; 4 Oct. 2019; Muhammad Asif, BWN -86; GenBank No. OK392605 (nrITS); LAH[36809]. Additional material examined PAKISTAN – Punjab Province • Sheikhupura City; 31°42′40″ N, 73°59′16″ E; 236 m a.s.l.; on muddy soil; 23 Jul. 2017; Aiman Izhar, SKP -04; GenBank No. OK392596 (nrITS); LAH[35718] • Haroonabad City, District Bahawalnagar; 29°60′81″ N, 73°14′67″ E; 163 m a.s.l.; on nutrient-rich loamy soil; 8 Sep. 2020; Muhammad Asif, AG -143; GenBank No. OK392606 (nrITS); LAH[36975]. Description Pileus 3–6.3 cm, plano-convex to applanate, hygrophanous, light grey (10YR8/1) to brownish grey (10YR4/1), subumbonate, some slightly depressed at the center, disc dull brown (7.5YR5/4), surface shiny, silky fibrillose, fibrils crowded at the center, radially translucent striate, striations prominent near margins, margins irregular, splitting on full maturity. Pileal veil white, fragile, powdery evanescent. Lamellae about 0.1–0.2 cm broad, moderately close, adnate to adnexed, in shades of dull orange (7.5YR7/4) to brown (10YR4/3), edges even, serrate, lamellulae present in 2–3 different lengths. Stipe 5.5–7 cm long, 0.3–0.5 cm diameter, equal, cylindrical with a small grainy bulb at the base, hollow, fragile, off-white (7.5Y9/2), apex pruinose, covered with white to greyish, evanescent fibrils. Basidiospores [60/3/3] (6.2–)7.2–7.6(–9.1) ×(4–)4.5–6(–6.3) µm, avl× avw = 7.5×5 µm, Q = 1.4–1.5, ellipsoid to oblong-ellipsoid, few elongated in face view, slightly flattened in side view, dull orange in water (5YR 6/4), greyish red (10R6/2) in 5% KOH, inamyloid, smooth, thick-walled, multi-guttulate, germ pore indistinct. Basidia 19.3–22.5×9.4–10.5 µm, broadly clavate, hyaline, thick-walled, weakly granular, mostly 4-spored, a few 2-spored. Cheilocystidia 21–38×9.6–16 µm, hyaline, moderately thick-walled, mostly lageniform to utriform, few fusiform, base with a tapered short to long stipe, abundant, smooth, no adhering deposits or crystals at apex. Pleurocystidia absent. Trama of gills irregular, consisting of septate hyphae, up to 6 μm. Pileipellis consists of thin-walled, hyaline, 2–3 cells deep layers of spherical, subglobose to columnar cells, 17.3–34.6 µm broad interspersed with very few septate 3–5 μm broad hyphae. Stipitipellis cuticle made up of 4.5–7 µm broad parallel, septate hyphae, rarely branched. Caulocystidia absent. Clamps are present throughout. Habitat Found from nutrient-rich loamy soil, along the canal bank under Vachellia nilotica (L.) P.J.H.Hurter & Mabb. (Fabaceae), and on rotten wood debris in muddy soil. Distribution This species is reported for the first time from two different locations in Punjab, Pakistan. Discussion In this study we identified a new fungal species of Candolleomyces collected from Punjab, Pakistan based on morpho-anatomical features and its phylogenetic placement. The combination of microscopic features, dull orange to greyish red basidiospores with indistinct germ pore, polymorphic, varying from lageniform to utriform, smooth cheilocystidia, lack of pleuro- and caulocystidia, and presence of clamp connections assigns this interesting species to the genus Candolleomyces which make it easy to recognize in the laboratory (Fig. 3). According to the taxonomy of Smith (1972), C. asiaticus sp. nov. belongs to Psathyrella section Subatratae (Romagn.) ex Sing, emended in having an evanescent veil, small basidiospores (5–10 µm long), and absence of pleurocystidia. The ITS sequences of C. asiaticus sp. nov. showed 99.8% similarity with sequences from Indian specimens (GenBank accession numbers KP686449, KP686452, KR154976, and KR154977) (Fig. 1). These specimens formed a well-supported clade with the Pakistani specimens analyzed in this study, clearly distinguishable from other species of Candolleomyces. The sequences KR154976 and KR154977 correspond to the vouchers BAB-4747 and BAB-4748 respectively, and KP686449 and KP686452 correspond to the vouchers BAB-4772 and BAB-4775 named as Psathyrella species in GenBank. These Indian collections should be also recognized as C. asiaticus based on our phylogenetic study, but their morpho-anatomical characteristics need to be studied and confirmed in future studies. In phylogenetic analysis, Candolleomyces asiaticus sp. nov. reveals to be close relative of C. cacao, a species described from São Tomé (Africa), but the latter has significant morphological differences such as convex to broadly convex pileus, smaller in diameter (0.5–1.5 cm), lack of partial veil, smaller basidiospores (5.7–6.8 × 3.5–4.8 µm) and frequent occurrence of caulocystidia (Desjardin & Perry 2016). Candolleomyces asiaticus sp. nov. is also phylogenetically related to C. subcacao but differs from it by its bigger basidiospores (6.3–9.1×4–6.3 μm) (vs 6.8–8.8 × 3.9–4.9 μm in C. subcacao; Bau & Yan 2021). A comparison of diagnostic characters of phylogenetically close species is also given in Table 2.