Pseudostaurosphaeria chromolaenicola Mapook & K.D. Hyde, sp. nov.

MycoBank number: MB 557356; Index Fungorum number: IF 557356, Facesoffungi number: FoF 07815; Fig. 69

Etymology: Name reflects the host genus Chromolaena, on which this species was growing.

Holotype: MFLU 20-0360

Saprobic on dead stems of Chromolaena odorata. Sexual morph: Undetermined. Asexual morph: Conidiomata 105–120 µm high × 85–120 µm diam. ( = 113 × 100 µm, n = 5), pycnidial, solitary, immersed to semi-immersed, uniloculate, globose to subglobose, pale brown to light brown. Ostiole central, short papillate. Pycnidial wall 5–15 µm wide, comprising 3–4 layers of thick-walled, hyaline or pale brown to light brown cells of textura angularis. Con- idiophores reduced to conidiogenous cells. Conidiogenous cells holoblastic, ampulliform to cylindrical, hyaline and unbranched. Conidia 6.5–9 × 5–6.5 μm ( = 7.6 × 6 µm, n = 45), oblong to obovoid, 1-transverse septum, later developing 1-vertical septum, muriform, smooth-walled, slightly constricted at the septum, yellowish brown to brown with single polar appendage from apex, observed clearly when mounted in Indian ink.

Culture characteristics: Conidia germinating on MEA within 48 h. at room temperature and germ tubes produced from both ends. Colonies on MEA circular, mycelium umbonate, entire, cultures white at the surface, olivaceous- brown to dark brown from the centre of the colony in reverse with creamy-white at the margin (Fig. 70b).

Pre-screening for antimicrobial activity: Pseudostaurosphaeria chromolaenicola (MFLUCC 17-1497) showed antimicrobial activity against M. plumbeus with an 18 mm inhibition zone, observable as partial inhibition, when com- pared to the positive control (18 mm), but no inhibition of E. coli and B. subtilis.

Material examined: THAILAND, Chiang Rai Province, Doi Pui, on dead stems of Chromolaena odorata, 2 April 2017, A. Mapook (DP90, MFLU 20-0359); living culture MFLUCC 17-1491; (DP96, MFLU 20-0360, holotype); ex-type culture MFLUCC 17-1497.

GenBank numbers: LSU: MN994571, MN994572, ITS: MN994594, MN994595, SSU: MN994617, MN994618, TEF1: MN998175, MN998176

Notes: In a BLASTn search of NCBI GenBank, the closest match with the ITS sequence of Pseudostaurosphaeria chromolaenicola (MFLUCC 17-1497, ex-holotype) with 93.91% similarity was Neosetophoma sp. (strain CFE-31, MK614774). The closest match with the LSU sequence with 98.46% similarity was Phaeosphaeria sinensis (strain C454, MK348022). The closest match with the SSU sequence with 99.82% similarity was Phaeosphaeria avenaria f. sp. triticae (strain ATCC 26370, EU189210), while the closest match with the TEF1 sequence with 96.81% similarity was Yun- nanensis phragmitis (strain MFLUCC 17-0365, MF683625). In the present phylogenetic analysis, Pseu. chromolaenicola clusters with Pseu. chromolaenae (MFLUCC 17-1490) with high bootstrap support (100% ML and 1.00 BYPP, Fig. 52). However, Pseu. chromolaenicola differs from Pseu. chromolaenae in having oblong to obovoid conidia with 1-transverse septum and later developing 1-vertical septum, while Pseu. chromolaenae has larger conidiomata (110–145 × 95–140 μm vs. 105–120 × 85–120 μm) and larger conidia (7–10 × 5–8.5 μm vs. 6.5–9 × 5–6.5 μm), with globose or oblong to obovoid, 1–2-transverse septa, later developing 1–2-vertical septa (Table 14). A comparison of the ITS (+5.8S) gene region of Pseu. chromolaenicola and Pseu. chromolaenae reveals 59 base pair differences (10.9%) across 539 nucleotides. Therefore, Pseu. chromolaenicola is described as a new species based on phylogeny and morphological comparison.

Table 14 Synopsis of Pseudostaurosphaeria species with similar morphological features discussed in this study

Species Conidiomata (μm) Pycnidial wall Conidia (μm) Septate of conidia Reference
P. chromolaenae (MFLUCC 17-1490) 110–145 high × 95–140 diam. 9–15 7–10 × 5–8.5 Globose or oblong to obovoid, 1–2-transverse septa, later devel- oping 1–2-vertical septa This study
P. chromolaeni- cola (MFLUCC 17-1497)

 

105–120 high × 85–120 diam. 5–15 6.5–9 × 5–6.5 Oblong to obovoid, 1-transverse

septum, later developing 1-verti- cal septum

This study

Fig. 52 Phylogram generated from maximum likelihood analysis based on combined dataset of LSU, ITS, SSU, TEF1 and RPB2 sequence data. Thirteen strains are included in the combined sequence analysis, which comprise 4416 characters with gaps. Tree topology of the ML analysis was similar to the BYPP. The best scoring RAxML tree with a final likelihood value of − 8333.195072 is presented. The matrix had 327 distinct alignment pat- terns, with 24.82% of undetermined characters or gaps. Estimated base frequencies were as follows: A = 0.252190, C = 0.233838, G = 0.264447, T = 0.249525; substitution rates: AC = 1.127465, AG = 2.895211, AT = 2.022869, CG = 0.534488, CT = 8.448227, GT = 1.000000; gamma distribution shape parameter α = 0.020000. Boot- strap support values for ML equal to or greater than 60% and BYPP equal to or greater than 0.90 are given above the nodes. Newly generated sequences are in dark red bold and type species are in bold. Phaeosphaeria oryzae (CBS 110110) is used as outgroup taxon

Fig. 69 Pseudostaurosphaeria chromolaenicola (holotype) a, b Appearance of conidiomata on substrate. c Section through of conidioma. d Ostiole. e Peridium. f-i Conidiogenous cells and developing conidia. j-l Conidia with appendages m Conidia with appendages in Indian ink. Scale bars: a = 500 µm, b = 200 µm, c, d = 20 µm, e-m = 10 µm

Fig. 70 Culture characteristics on MEA: a Pseudostaurosphaeria chromolaenae (MFLUCC 17-1490). b Pseudostaurosphaeria chromolaenicola (MFLUCC 17-1497)