Kionochaeta setosimplicia Chuaseehar., Somrith. & Boonyuen, 2021

Nuankaew, Salilaporn, Chuaseeharonnachai, Charuwan, Somrithipol, Sayanh, Kwantong, Papichaya, Srihom, Charisa, Ros, Chandapheakdey & Boonyuen, Nattawut, 2021, Contribution to Chaetosphaeriaceae-Kionochaeta setosimplicia sp. nov. from Thailand, Phytotaxa 508 (2), pp. 175-186 : 181

Kionochaeta setosimplicia Chuaseehar., Somrith. & Boonyuen , sp. nov. ( FIGURE 2 )

Mycobank number: MB839136

Etymology:—referring to simple setae arising beside the conidiophore.

Saprobic on a submerged decaying twig of an unidentified plant. Asexual morph: Colonies on plant substratum effuse, caespitose, glistening, with a light yellow and slimy mass of conidia. Mycelium mostly immersed, partially superficial. Setae subulate, erect, acute, sterile, arising beside the conidiophores, smooth-walled, unbranched, septate, dark brown, 227.5–400 μm high, 7.5–8 μm wide at the base. Conidiophores macronematous, mononematous, solitary, setiform, erect, straight or slightly curved, smooth- and thick-walled, branched; with 2–26 sterile lateral branches situated below the middle part of central element, septate, dark brown and swollen at the base, paler towards the acute apex, 210–320 μm high, 7.5–15 μm wide at the base (av. = 276.8 × 9; n = 15). Lateral branches setiform, curved, sterile, smooth-walled, septate, brown to dark brown, 47–160 μm long, 3–7.5 μm wide at the base. Fertile region borne below the median part on the conidiophores, around the base of the lateral setiform branches, comprising of a mass irregularly short branches upon which conidiogenous cells are borne, 35–50 μm high, 27.5–70 μm wide. Conidiogenous cells monophialidic, discrete, determinate, terminal, ampulliform to short lageniform or oblong, with an indistinct collarette, pale brown, 5–8 × 2–3 μm (av. = 6.2 × 2.6 μm; n = 20). Conidia acrogenous, solitary, falcate, fusiform, smooth-walled, aseptate, slimy, hyaline, 6–7 × 1–1.2 μm (av. = 6.7 × 1 μm, n = 50). Conidial secession schizolytic. Sexual morph: Undetermined.

Material examined:— THAILAND. Chon Buri Province: Khao Kheow Open Zoo, Si Racha District , on a submerged decaying twig of an unidentified plant, 22 August 2018, C. Ros and C. Chuaseeharonnachai ( BBH 49002 holotype, TBRC 14899 ex-type living culture; BBH 49003 isotype, TBRC 14900 ex-isotype living culture) .

Notes: Morphologically, Kionochaeta setosimplicia is unique and differs from other accepted Kionochaeta taxa by the presence of sterile lateral setiform branches and sterile setae arising beside the conidiophores ( FIGURE 1 ; no.4 and FIGURE 2 ; a–b). In this study, Kionochaeta setosimplicia is compared with five closely related species viz., K. australiensis , K. castaneae , K. keniensis , K. pughii and K. ramifera ( Matsushima 1971, Kirk 1985, Kirk & Sutton 1985, Kuthubutheen & Nawawi 1988, Goh & Hyde 1997, Lin et al. 2019). In TABLE 2, K. setosimplicia resembles K. nanophora possessing setae along with the conidiophore, but setae of the latter are apically fertile or swollen ( FIGURE 1 ; no.1). In K. nanophora , it can be separated from the new species in having conidiophores with apical conidiogenous apparatus and in lacking lateral setiform branches ( Kuthubutheen & Nawawi 1988). The novel taxon shares morphological features with K. keniensis and K. ramifera ( FIGURE 1 ; no.6) by having sterile tips of a central element and lateral branches, and has a single locus of the fertile region at the sub-median part of conidiophores. However, the new fungus has sterile setae alongside the conidiophores, possessing more sterile lateral branches (2–26) and smaller conidia (6.0–7.0 × 1.0–1.2 μm) than those of other species as follows: K. keniensis (11.0–)12.0–16.0 (excluding the setulae) × 1.5–2.5 μm (Kirk 1985) and K. ramifera (5–)6–10(–12) × 1.0–1.5 (–2.0) μm ( Matsushima 1971).

Figures

FIGURE 1. Phylogenetic tree generated from RAxML based on the combined SSU, ITS, LSU and RPB2 sequences. Bootstrap support values for maximum likelihood (ML) and maximum parsimony (MP)> 50% and Bayesian posterior probabilities (PP)> 0.95 are indicated above each branch as ML/MP/PP, respectively. Bootstrap support values of MP, ML = 100% and PP = 1.00 are indicated with thickened branches. Ex-type strains are in bold and the new species are in purple. The morphologies of seven selected species shown in the tree are illustrated in panels on the right. Red dots (1–7) refer to tightly branched loci with multiple conidiogenous cells. Brown dots (1, 3, 5, 7 & 8) indicate loosely branched loci with a single conidiogenous cell. The black dot (1) indicates a swollen or lobed apex of the seta.

FIGURE 2. Kionochaeta setosimplicia (holotype, BBH 49002). a. Colony with setae (arrow) on woody substrate. b. Conidiophore with seta. c–d. Conidiophores. e–f. Seta. g–h. Conidiophore, conidiogenous cells and conidia. i. Conidia. Scale bars: a–f = 50 μm. g = 20 μm. h, i = 5 μm.