Endocalyx phoenicis Senan. & K.D. Hyde, sp. nov.
Index Fungorum number: IF 900459; MycoBank number: MB 900459; Facesofungi number: FoF 14214; Fig. 1
Etymology – Refers to the name of the host genus, Phoenix.
Saprobic on dead petioles of Phoenix roebelenii O’Brien. Sexual morph: Undetermined. Asexual morph: Conidiomata 230–250 µm diam., 250–270 µm high, scattered or aggregated, emerging from annulus-like, black, circular pustules, short, cylindrical or cup-shaped, reaching up to 100 mm high, well-developed, consisting of dark brown, conidial mass enclosed by greenish yellow, mass of sterile peridial hyphae. Sterile peridial hyphae grow upwards surrounding the conidial column, hyaline to olivaceous, ends bulbous with greenish yellow, globose bulbs. Conidiomata wall 60–70 μm wide, thick, comprising dark brown cells of textura angularis. Conidiophores reduced to conidiogenous cell. Conidiogenous cells 15–20×1.5–2.5 µm long (x=18×2 μm, n=20), holoblastic, monoblastic, integrated, terminal, cylindrical, flexuous, hyaline, septate, smooth. Conidia 10–15×8–10 µm (x=13×10 μm, n=30), globose to subglobose, unicellular, dark brown, with a paler equatorial germ slit, thick-walled, smooth to finely roughened, often with a central attachment scar.
Culture characteristics – Colonies on PDA reaching 6 cm diam., after seven days at 25 °C, white at first, irregular, raised, undulate, rough, after maturity, smooth at the margin, white from above, pale-brown from below.
Material examined – China, Guangdong Province, Shenzhen City, Futian District, northwest of Futian, Bijiashan Park, on dead petioles of Phoenix roebelenii (Arecaceae), 8 June 2020, I.C. Senanayake, SI 2-2 (MHZU 22-0078, holotype), ex-type cultures ZHKUCC 22-0135, ZHKUCC 22-0128.
GenBank numbers – ITS: OR164914, OR164915.
Notes – The sequence data of ITS, and LSU of our isolate (ZHKUCC 22-0135) gives species in Endocalyx as the closest matches with NCBI. The phylogenetic analysis (Fig. 2) showed that our isolate grouped with E. ptychospermatis Y.R. Xiong, Manawas & K.D. Hyde and E. melanoxanthus (Berk. & Broome) Petch, but distinct from them forming a separate subclade with MP/BI=93%/1.00 support. Comparison of the sequence of ITS, and LSU locus of our isolate (ZHKUCC 22-0135) with strains of E. ptychospermatis and E. melanoxanthus revealed the base pair differences of 1.02%, 5.66%, 0.34% and 2.51% respectively. Our collection (MHZU 22-0078) is morphologically different from E. melanoxanthus by absence of conidiophores, smooth-walled conidiogenous cells and only globose to sub-globose-shaped conidia while E. melanoxanthus comprises anastomosing, micronematous, filiform conidiophores, minutely denticulate conidiogenous cells with intercalary conidiogenesis, conidia with broadly ellipsoidal, slightly polygonal and fattened in front view and ellipsoidal, lenticular or rarely oblong in lateral view. Endocalyx ptychospermatis has wider (470–520 µm diam.) conidiomata and elliptical to closed polygonal conidia with verrucous inclusions and our collection has narrowed (230–250 µm diam.) conidiomata with globose to sub-globose conidia. Most species in Endocalyx are reported from Arecaceae plants as saprobes. Therefore, ecological and life mode data are uninformative for species identification. We introduce our collection as a new species, Endocalyx phoenicis.
Figure 1 – Endocalyx phoenicis (MHZU 22-0078, holotype). a Host. b Examined material. c Lateral view of conidiomata. d Upper view of conidiomata on the natural substrate. e Cross section of conidioma. f Sterile peridial hyphae. g–j Conidiogenous cells attached to conidia. k, l Conidia. Scale bars: e=300 µm, f–l=15 µm
Figure 2 – Phylogram generated from maximum likelihood analysis based on combined ITS and LSU sequence data of 40 taxa, which comprised 1514 characters (ITS=635 bp, LSU=879 bp). The best scoring RAxML tree with a final likelihood value of − 8357.252007 is presented. The matrix had 582 distinct alignment patterns, with 14.19% of undetermined characters or gaps. Estimated base frequencies were as follows: A=0.250270, C=0.238774, G=0.272133, T=0.238823; substitution rates: AC=1.344249, AG=1.787142, AT=1.867513, CG=1.324573, CT=4.906484, GT=1.0; gamma distribution shape parameter α=0.225328. Bootstrap support for maximum likelihood (ML) equal to or greater than 50% and clade credibility values greater than 0.90 (the rounding of values to 2 decimal proportions) from Bayesian inference analysis are labelled at each node. Ex-type strains are in bold, while the new isolate is indicated in blue bold. The tree is rooted to Arthrinium caricicola (ALV16691)