Hysterium madraspatanum Kumar. M, Nivetha. M, & Agnes K.A.

Manogaran, Nivetha, Kayalvizhi, Agnes & Munuswamy, Kumar, 2024, Hysterium madraspatanum (Hysteriaceae), a new species from Tropical Dry Evergreen Forest of Tamil Nadu, India, Phytotaxa 649 (1), pp. 98-110 : 100-103

Hysterium madraspatanum Kumar. M, Nivetha. M, & Agnes K.A. sp. nov. ( Figs. 1 & 2 )

Mycobank number: MB849745

GenBank number: OR420067

Etymology: —Named after the region Madras where the type specimen was collected.

Saprobic on deadwood of Azadirachta indica . Telomorph: Ascomata typically hysterithecioid, ovoid to elongated ellipsoid, arising singly or in small groups, straight or irregularly curved, slightly erumpent, somewhat laterally compressed in the basal region, slit sulcate, very shallow, existing as a narrow rim with a conspicuous longitudinal cleft and often with 1–2 inconspicuous parallel striations, sessile on the substrate, 0.5–1.5 × 0.2–0.3 mm (20). Peridium with lateral walls, composed of very dark, opaque, thick walled brown–black cells of textura globosa. Pseudoparaphyses hyaline, 1–1.5 μm wide, filiform with thickened tips, branched above the ascal layer to form an epithecium. Asci bitunicate, arises from the basal hymenial layer, cylindrical to clavate, short pedicel, hyaline, 8-spored, (110–)115–122 × 20–22 μm. Ascospores biseriate, initially two celled, four celled at maturity, initially hyaline to dark brown at maturity, oblong to ellipsoid, (28–) 34–(39) × (7–) 9–(–12) μm when mature. Anamorph: Undetermined.

Material examined: — INDIA, Tamil Nadu, Chennai, Madras Christian College Campus , near Boxing ring, on dead wood of Azadirachta indica tree ( Meliaceae ), 12° 55’ 16.6836’’ N 80° 7’ 14.6928’’E, 11 th January 2021, Nivetha. M Specimen Code: MCCHF210111 .

Notes: — Hysterium madraspatanum is morphologically similar to H. angustatum ( Jayasiri et al. 2018) by having central slit unopened but H. angustatum is smooth and lacks any other striations on the ascomata, while H. madraspatanum has few parallel striations ( Fig.2 a–d ). Microscopically H. madraspatanum resembles H. angustatum by having biseriate arrangement of spores but H. madraspatanum has larger spores (28–39 µm) and strictly 3 septate than H. angustatum (16–30 µm), 3 septate and rarely 4 septate. The Hysterium rhizophorae (Devdatha et al. 2018) differs from H. madraspatanum by having overlapping biseriate ascospores which are much smaller (10–17 µm) and has a constriction in the median septum. Also H. madraspatanum closely resembles the ascomata morphology of H. pulicare (Boehm et al. 2009) in having striated ascomata but the central groove is prominent.

The spore morphology of H. madraspatanum closely resembles the spores of H. pulicare but the terminal cells in Hysterium pulicare are hyaline whereas the spores of H. madraspatanum are concolorous which is a remarkable characteristic feature to diverge from H. pulicare and establish as a new species.

The single locus analyses itself provides clear indication of the species being new by aligning in a separate clade with 35 bp difference. The result is found satisfactory even with the single dataset in order to erect as a new species. Although at present we haven’t analysed using other datasets, the morphological data and phylogenetic analyses clearly indicate the uniqueness of the species. Therefore H. madraspatanum is established as a new species.

Figures

FIGURE 1: Hysterium madraspatanum. a Habit. b Ascospores. c Various stages of ascus with ascospores. d Pseudoparaphyses showing the branching pattern. Scale bars: a = 0.5 mm, b = 20 µm, c = 20 µm, d = 10 µm.

FIGURE 2: Hysterium madraspatanum. a–d Ascomata on host surface. e–g Hamathecium. e–g Hamathecium of H. madraspatanum. h young developing ascus. i–j Ascus with biseriate ascospores. k Pseudoparaphyses. l young spore showing single septum. m–p Various stages of ascospores. Scale bars: a–b = 2 mm, c–d = 1 mm, e = 0.2 mm, f–g = 0.1 mm, h = 5 µm, i–j =10 µm, k =5µm, l–p = 10µm.