Leucoagaricus callainitinctus K. P. D. Latha, K. N. A. Raj & Manim., 2020

Deepna Latha, K. P., Anil Raj, K. N. & Manimohan, Patinjareveettil, 2020, Leucoagaricus callainitinctus-a new species of Leucoagaricus section Piloselli (Agaricaceae) from tropical India, Phytotaxa 442 (2), pp. 111-120 : 113-118

Leucoagaricus callainitinctus K. P. D. Latha, K. N. A. Raj & Manim. , sp. nov. Figs. 1–2

MycoBank MB 834942

Etymology:—From the Latin words callainus (turquoise) and tinctus (dyed); refers to the characteristic turquoise discolouration of the basidiocarps.

Diagnosis:—Differing from Lepiota harithaka in having basidiocarps that turn dark turquoise (24 E5, 24 F5) on handling/bruising or reacting with NH 4 OH, an appressed-squamulose pileus devoid of a pruinose centre, with white, cottony velar remnants on and around the margin, pseudocollariate lamellae, a shorter, yellowish white or greyish yellow stuffed stipe, a white spore print with a tint of cream, a pleasant odour, metachromatic basidiospores, variously shaped cheilocystidia that are devoid of crystalline encrustations, a trichoderm-type pileipellis, a disrupted cutis-type stipitipellis with isolated or bunches of cystidioid terminal elements and distinctive nrITS sequence and position in the phylogram.

Holotype:— INDIA. Kerala State: Malappuram District, Mayilanji Valavu , 11° 08.034′ N, 075° 52.156′ E, 18 June 2018, K. P. Deepna Latha & K. N. Anil Raj DKP503 ( CAL 1799 ). GenBank accessions: MT108797 (nrITS), MT108798 (nrLSU).

Description:— Basidiocarps small, more or less collybioid. Pileus 4–29 mm diam., paraboloid or obtusely conical when very young, becoming campanulate and finally convex or broadly convex with a low, broad umbo, at times with a shallow depression around the umbo; surface dark brown (6F7/OAC734) all over when young, becoming dark brown (6F7/OAC734) on the squamules and brownish orange (6C3/OAC753) elsewhere with age, appressed-squamulose all over with white, cottony velar remnants on and around the margin when young, becoming appressed- to slightly recurved-squamulose, densely so towards the centre and often minutely cracking, still with scattered velar remnants towards the margin with age; margin initially incurved, becoming decurved to somewhat reflexed with age, wavy or slightly appendiculate. Lamellae free, with a pseudocollarium, crowded, initially yellowish white (4A2/OAC899), becoming pale yellow (3A3/OAC898) at maturity, up to 4 mm wide, with lamellulae in 3–6 tiers; edge crenate under a lens, concolourous with the faces. Stipe 16–46 × 2–6 mm, centrally attached, terete, slightly tapering towards the apex, stuffed; surface initially yellowish white (4A2/OAC900), becoming greyish yellow (4B3/OAC850) at maturity, appressed-fibrillose all over as well as appressed- to slightly recurved-squamulose over entire length; base subbulbous, with white basal mycelium. Partial veil present and distinct, orange-grey (6B2/OAC780) when young, fugacious and disappearing when mature without leaving an annulus. Context up to 2 mm thick, white or off-white, soft. Odour faint, pleasant. Taste not recorded. Spore print white (4A1/OAC900) with a tint of cream. All parts of the basidiocarps turn dark turquoise (24 E5, 24 F5/OAC168) on bruising or on handling. Dried basidiocarps brownish grey (7F2/OAC639) or at times with patches of reddish grey (12C2/ OAC514) especially on the lamellae and stipe.

Basidiospores 5–7 × 3–4 (6.7 ± 1.3 × 3.9 ± 0.4) µm, Q= 1.2–4.3, Qm = 1.73, (some basidiospores exceptionally large and up to 8–13 × 4.5–5 µm), oblong-ellipsoid, amygdaliform or somewhat fusiform, with a conspicuous hilar appendix, smooth, thin- to slightly thick-walled (up to 0.75 µm thick), without a germ-pore, hyaline, with refractive guttules, dextrinoid, cyanophilous, congophilous, metachromatic in cresyl blue. Basidia 12–23 × 5–8 µm, clavate, hyaline, thin-walled, 4-spored or sometimes in some basidiocarps 1- or 2-spored; sterigmata up to 4.5 µm long. Lamella-edge heterogeneous, crowded with tufts of cheilocystidia. Cheilocystidia 18–32 × 7–13 µm, mostly broadly pedicellate-clavate, at times narrowly utriform, sphero-pedunculate, or clavate with a mucronate apex or with a strangulated or flexuose, apical prolongation up to 23 µm long and 3 µm wide, thin- to slightly thick-walled, hyaline. Pleurocystidia absent. Lamellar trama subregular; hyphae 3–8 µm wide, inflated up to 20 µm, thin-walled, hyaline, inamyloid. Subhymenium pseudoparenchymatous. Pileus trama interwoven, composed of both narrow and inflated hyphae; hyphae 3–16 µm wide, thin-walled, with a pale yellow wall pigment, inamyloid. Pileipellis a trichoderm composed of tufts of ascending or erect chains of cystidioid elements; hyphae 3–11 µm wide, thin- to slightly thick-walled, with a pale yellow wall pigment, inamyloid; terminal elements cystidioid 24–118 × 7–28 µm, versiform: narrowly clavate, clavate, subglobose, fusiform, cylindrical with an obtuse apex, ellipsoidal or utriform, thick-walled (up to 1 µm thick), hyaline or with a pale yellow wall pigment and yellowish brown amorphous contents, inamyloid. Stipitipellis a cutis disrupted by solitary or bunches of cystidioid terminal elements; hyphae 2.5–10 µm wide, thin- to slightly thick-walled, hyaline or with a pale yellow wall pigment, inamyloid; terminal elements cystidioid, 37–126 × 6–31 µm, narrowly clavate, clavate, cylindrico-clavate or narrowly utriform, thick-walled (up to 1 µm thick), with a pale yellow wall pigment, inamyloid. Caulocystidia absent. Clamp connections not observed on any hypha.

Macrochemical reactions:—Pileus, lamellae and stipe turning dark turquoise with 10 % NH 4 OH.

Habitat: — On soil, scattered or in small groups, amongst roots of living bamboo ( Bambusa striata ).

Geographical distribution range:—Known only from the type locality in Kerala State, India.

Additional specimens examined:— INDIA. Kerala State: Malappuram District, Mayilanji Valavu , 25 June 2018, K. P. Deepna Latha DKP505 (Deepna Latha personal herbarium) ; 28 July 2018, K. P. Deepna Latha DKP526 ( CUH AM700 ) ; 10 July 2019, K. P. Deepna Latha DKP551 (Deepna Latha personal herbarium) ; 27 July 2019, K. P. Deepna Latha & K. N. Anil Raj DKP566 (Deepna Latha personal herbarium) ; 12 August 2019, K. P. Deepna Latha & K. N. Anil Raj DKP586 ( CUH AM701 ) .

Comments:—A set of morphological features such as basidiocarps discolouring with NH 4 OH, a non-striate pileus, a cream-tinted spore print, smooth, metachromatic basidiospores without a germ pore, hyphae devoid of clamp connections, a trichoderm-type pileipellis and the absence of apical excrescence on the cheilocystidia are suggestive of subsect. Pilatianei and sect. Piloselli of the genus Leucoagaricus ( Singer 1973, 1986; Vellinga 2010; Vellinga et al. 2010). Although several species of Leucoagaricus show discolouration when reacting with ammonia or KOH, L. callainitinctus is remarkable in turning turquoise even in the absence of ammonia and KOH. Lepiota harithaka T.K.A. Kumar & Manimohan (2009a: 133) , a species that likely belongs in Leucoagaricus sect. Piloselli and described from Kerala ( Kumar & Manimohan 2009a), seems very close to Leucoagaricus callainitinctus in having basidiocarps that change colour on bruising, a non-striate, brown, squamulose pileus, crowded, pale yellow lamellae, a fibrillose stipe with a slightly bulbous base, a whitish context, basidiospores of somewhat similar size (5–7 × 3–4 µm) and shape and lacking a germ pore, similar-sized basidia, slightly thick-walled cheilocystidia, subregular lamellar trama, slightly thick-walled hyphae of the pileipellis and stipitipellis and hyphae lacking clamp connections. Besides these characters, these two species seem to share a common habitat as well. Basidiocarps of both the species are seen on soil amongst roots of bamboo ( Kumar & Manimohan 2009a). However, Lep. harithaka differs from L. callainitinctus by its greyish green (27E5) bruising reaction of the basidiocarps, a dull white and granulose pileus with a pruinose centre, lamellae not attached to a pseudocollarium, a whitish and smooth stipe, a superior, whitish, membranous annulus, a yellowish white spore print, non-metachromatic basidiospores that are with lower Q (1.4–2) and Qm (1.6) values and never fusoid in shape, consistently 4-spored basidia with a pale green colour, a sterile lamella-edge with slightly broader cheilocystidia that are generally clavate with greenish contents and speckled crystalline encrustations, pale green-coloured and slightly thick-walled hyphae of lamellar and pileus trama, a disrupted cutis-type pileipellis which becomes a trichoderm only at the centre with smaller terminal elements (27–65 × 10–20 μm) with dark grey plasmatic and encrusting pigments and a cutis-type stipitipellis rarely disrupted by ascending hyphae with a pale grey colour ( Kumar & Manimohan 2009a).

Leucoagaricus viriditinctus (Berkeley & Broome) J.F. Liang, Zhu L. Yang & J. Xu (in Liang et al. 2010: 1146), a species originally described as Agaricus viriditinctus Berkeley & Broome (1871: 503) and then as Lepiota viriditincta (Berkeley & Broome) Saccardo (1887: 57) , from Sri Lanka ( Pegler 1986) and India ( Manimohan et al. 1988) and finally in the present name from China ( Liang et al. 2010), seems to be somewhat similar to L. callainitinctus in having a slightly umbonate pileus with dark brown squamules, a white context, an attenuated stipe with an inflated base, basidiospores of somewhat similar shape and size ((6.5–)7.0–8.5 × 4.0–5.0 mm) and lacking a germ pore, cheilocystidia of similar morphology and hyphae devoid of clamp connections. However, L. viriditinctus has slightly larger basidiocarps (pileus 10–35 mm, stipe 15–65 × 1–4 mm), a pileus at times with striations, moderately crowded lamellae that never form a pseudocollarium, a white, hollow stipe, a white, membranous annulus, a dark blue discolouration of the context, stipe and the annulus on bruising, longer and consistently 4-spored basidia, larger cheilocystidia (10–50 × 7.5–21 μm) and a loosely organised cutis-type pileipellis with thin-walled terminal elements showing a pale brown intracellular pigment and brown encrustations ( Liang et al. 2010).

Leucoagaricus atroazureus J.F. Liang, Zhu L. Yang & J. Xu (in Liang et al. 2010: 1144), a species described from China ( Liang et al. 2010), shares with L. callainitinctus a few features such as a dark brown, squamulose pileus, a white context, somewhat similarly coloured lamellae, a yellowish white stipe, basidiospores of somewhat similar size (5.0–)5.5–8.0 (–9.0) × (3.0–)3.5–5.0(–6.0) μm) and shape and devoid of a germ pore, basidia of similar size with 4 and 2 sterigmata, lamella-edges with cheilocystidia and clampless hyphae. However, L. atroazureus differs in having larger basidiocarps (pileus 16–45 mm, stipe 22–40 × 2–6 mm), a blackish red to brownish red pileus with a dirty white margin, a context that becomes dark blue on bruising or on drying, lamellae that never form a pseudocollarium, a fistulose, nearly glabrous stipe which is greyish orange at maturity and turning dark blue when bruised or dried, a superior, white annulus that becomes dark blue on drying, larger and clavate or fusiform cheilocystidia, a loosely arranged cutis-type pileipellis with hardly differentiated terminal elements that are thin-walled and with brown intracellular pigment and brown encrustations ( Liang et al. 2010).

The characteristic discolouration of the basidiocarps on bruising is found in several other species of lepiotaceous agarics ( Akers et al. 2000; Kumar & Manimohan 2009a; Liang et al. 2010). Leucoagaricus coerulescens (Peck) J. F. Liang, Zhu L. Yang & J. Xu (in Liang et al. 2010: 1147), a species earlier described from Eastern North America as Lepiota coerulescens Peck (1899: 63) is an example. That species differs from L. callainitinctus in having white lamellae, consistently 4-spored basidia, a cutis-type pileipellis with poorly differentiated, thin-walled terminal elements with a pale brown intracellular pigment and in the non-persistence of bruising discolouration in the dried basidiocarps. Leucoagaricus flavovirens J.F. Liang, Zhu L. Yang & J. Xu (in Liang et al. 2010: 1143), L. viridiflavoides B.P. Akers & Angels (in Akers et al. 2000: 41), L. sulphurellus ( Pegler 1983: 420) B.P. Akers (in Akers et al. 2000: 48), Lepiota subcitrophylla Hongo (1956: 148) , Lep. trichroma Montoya & Bandala (2006: 112) and Leucocoprinus viridiflavus (Petch) E. Ludwig (2012: 554) also exhibit similar discolouration on bruising, but differ in several other characters ( Kumar & Manimohan 2009a, Akers et al. 2000; Montoya & Bandala 2006; Liang et al. 2010).

In the BLASTn search with the nrITS (679 bp) sequence of L. callainitinctus , the closest hit was Leucoagaricus species 2 GMB-2014 from Australia (96.31%, KP012819) followed by Lepiotaceae sp. PA341 (85.20%, AF079747) from Panama and Lepiotaceae sp. BR006 (85.20%, EF527287) from Brazil. With the nrLSU sequence (924 bp), L. atroazureus HKAS 48450 (97.62%, EU416300) and L. flavovirens HKAS 50024 (97.62%, EU416296) were the closest hits. In the phylogram generated from the nrITS-based ML analysis ( Fig. 3 ), L. callainitinctus was nested in a cluster composed mainly of the members of sect. Piloselli . Within this large cluster, the new species was found to be a distinct lineage sister to an unpublished Australian collection, Leucoagaricus species 2 GMB-2014 with maximum bootstrap support (100 % BS).

Figures

FIGURE 1. Leucoagaricus callainitinctus (CAL 1799, holotype). A–B, D. Basidiocarps in their natural habitat; C. Basidiocarps showing their partial veil; E. Lamellae turning green when reacting with 10 % NH OH. Scale bars: A = 5 mm, B–E = 10 mm. Photos by: K. N. 4 Anil Raj

FIGURE 2. Leucoagaricus callainitinctus (CAL 1799, holotype). A. Basidiospores in cresyl blue; B. Basidiospores in cotton blue; C. Basidiospores in Melzer’s reagent; D. Basidiospores in Congo Red, note the presence of some exceptionally large spores as discussed in the text; E. Basidia; F–G. Cheilocystidia; H. Stipitipellis; I. Pileipellis; J. Cystidioid terminal elements of pileipellis. Scale bars: A–G, J = 10 μm, H = 20 μm, I = 50 μm. Photos by: K. P. Deepna Latha

FIGURE 3. Phylogenetic tree of Leucoagaricus callainitinctus based on ML analysis of nrITS region. Bootstrap supports (BS) are indicated to the supported node. The newly described species is indicated in boldface. GenBank accession numbers and geographical origin are given after the name of each taxon. BS values ≥50% are shown.