Comoclathris acuminata A.J. Mattoo, S. Nonzom & A. Ghosh, 2023

Mattoo, Aroosa Jan, Ghosh, Aniket & Nonzom, Skarma, 2023, Comoclathris acuminata (Pleosporaceae, Pleosporales): A new endophytic species from Indian Himalayas, Phytotaxa 589 (3), pp. 230-244 : 236-237

Comoclathris acuminata A.J. Mattoo, S. Nonzom & A. Ghosh sp. nov.

Figures 2–3

Mycobank:—MB 847073

GenBank: MW205771 (nrITS, holotype), OQ547243 (nrITS), OQ547244 (nrLSU, holotype), OQ547245 (nrLSU).

Etymology:—Specific epithet ‘ acuminata ’ refers to the ascospores with pointed apex.

Holotype:— INDIA. Ladakh: Kargil district, Namkila pass, isolated as an endophyte from stem of Ephedra gerardiana Wall. ex Stapf (Ephedraceae) , 3700 msl elev., 34°20ʹ.10ʹʹN, 76°33ʹ.21ʹʹE, 13 October, 2019, A.J Mattoo & S. Nonzom E2/MN2 (holotype MCC 9771 ), preserved in a metabolically inactive form.

Diagnosis:— Comoclathris acuminata differs from C. spartii by having larger ascomata, dark-brown ascospores with pointed apex and from C. antarctica by having superficial ascomata, larger asci and ovoid to elliptical ascospores with acuminate apex.

Description:— Mycelium brown,hyphae septate, branched,5–12 µm wide. Ascomata perithecial,slightly immersed to erumpent, (75–) 150–225 (–300) µm (n= 57) in diam., solitary, scattered or aggregated into small groups, globose to sub-globose, dark brown to black, with an inconspicuous, 47–103 μm ostiole; perithecial hyphae brown to dark brown, 4–7 µm wide. Peridium (9.8–) 21.7–29.1 (–33) µm wide, with 2–4 layers of dark brown to lightly pigmented cells of textura angularis. Asci (112–) 143–165 (–190) × (23–) 33–43 (–45) µm (x̅ = 154 × 38 µm, n= 36), 8-spored, cylindroclavate, stipitate; stipe slightly curved; bitunicate, fissitunicate, (15–) 30–36 (–40) × (3–) 4–5 (–6) µm (x̅ = 33 × 5 µm, n= 11); apex round, with a distinct, shallow ocular chamber. Hamathecium comprising numerous, (1.4–) 1.9–2.4 (–2.8) µm (n= 16) wide, cellular, filamentous, anastomosing pseudoparaphyses. Ascospores (17–) 24–29 (–30) × (13–) 14–17 (–18) µm (x̅ = 26 × 15 µm, n= 70), uni- to bi-seriate in asci, partially overlapping, golden when immature, darkbrown at maturity, roughly ovoid to elliptical, smooth, constricted at the middle transverse septum, upper half slightly broader than the lower half, clavate, muriform, with 3–8 transverse septa, 3–5 vertical septa, consisting of 15–21 cells; characteristically pointed at the apex, apical cell mostly undivided, with a beak-like extension; beak 2.1–5 × 2.6–4 µm (x̅ = 3.5 × 3.3 µm, n = 15); basal cell broad, rounded. Asexual morph undetermined.

Culture characteristics:—Colonies on PDA restricted, 15–20 mm in diam. after incubating for 25 days at 25±2℃; surface floccose, radiated, mouse grey, centre elevated, with white undulating margin; margins broad; reverse light brown, centre hollow, elevated, initially sterile, sporulating after induction treatment of 1–2 cold shocks on PDA at 4℃. Colonies after sporulation adpressed to medium, surface dark brown to black, with brown margins, appear spotted due to black superficial ascomata, 30–45 mm in diam. after eight weeks of incubation at 25±2℃; reverse black, hollow in the centre, sometimes forming ridges and grooves. On MEA, colonies restricted, 8–9 mm in diam. after incubating for 25 days at 25±2℃, closely adpressed to medium, surface suede-like, with dense felt of hyphae, radially sulcate, centre mouse-grey, elevated, margins white, narrow, entire; reverse furrowed; furrows deep; centre black, elevated, appears hollow; margins light brown. On CDA, colonies 13–16 mm in diam., surface flat or slightly elevated in the centre, centre broad, grey, margins off-white, narrow, diffused, undulating; reverse unevenly furrowed, furrows shallow, dark brown to black centre, with light-brown periphery.

Habitat and distribution:— Endophytic in the stem of Ephedra gerardiana growing in the cold arid desert of Ladakh, India.

Additional specimen examined:— INDIA. Ladakh: Kargil district, Namkila pass, isolated as an endophyte from stem of Ephedra gerardiana Wall. ex Stapf (Ephedraceae) , 3700 msl elev., 34°20ʹ.10ʹʹN, 76°33ʹ.21ʹʹE, 13 October, 2019, A.J Mattoo & S. Nonzom, MN3-2019.

Notes:— Phylogenetically, Comoclathris acuminata formed a distinct and independent clade closer to C. antarctica exhibiting 70% ML, 0.98 BPP (477/495bp nrITS; 807/813bp nrLSU) bootstrap support value ( FIGURE 1 ). Morphologically, C. acuminata conforms to the generic concept of Comoclathris by having brown to black, ostiolate ascomata, cylindro-clavate asci with an apical chamber, reddish-brown to dark brown, muriform ascospores. Comparative account of micromorphological features of C. acuminata with its allies is given in TABLE 2 .

Figures

FIGURE 1. Phylogram generated by Bayesian analysis based on combined sequence data of nrITS and nrLSU for Comoclathris acuminata and its allied species. Maximum Likelihood bootstrap support values (MLbs) ≥ 70% are shown on the left of “/” and Bayesian Posterior Probabilities (BPP) ≥ 0.95 are shown on the right above or below the branches at nodes. The new species is placed in red font to highlight its phylogenetic positions in the tree. Scale bar = 0.05.

FIGURE 2. Comoclathris acuminata (MCC 9771, holotype). a, b Ascomata on nutrient medium. c–e Magnified view of ascomata and the release of asci. f Clavate ascus with 8 overlapping ascospores. g Empty ascus. h Asci with haemathecium. i Ruptured ascus with muriform ascospores. j Magnified view of stipe. k–n Ascopsores. Scale bars a = 400 μm, b–e = 200 μm, f, g = 10 μm, h = 20 μm, i–n = 10 μm. Photo credit:Aroosa Jan Mattoo.

FIGURE 3. Cultural characteristics of Comoclathris acuminata. a Isolation plate showing the emergence of mycelium from the surface sterilized stem segment. b Colony on PDA before sporulation. c Colony after sporulation induction on PDA. d, e Colonies on MEA and CDA, respectively.