Comoclathris clematidis R. Xu, Phukhams. & Y. Li, 2024

Xu, Rong, Su, Wenxin, Wang, Yang, Tian, Shangqing, Li, Yu & Phukhamsakda, Chayanard, 2024, Morphological characteristics and phylogenetic evidence reveal two new species and the first report of Comoclathris (Pleosporaceae, Pleosporales) on dicotyledonous plants from China, MycoKeys 101, pp. 95-112 : 95

Comoclathris clematidis R. Xu, Phukhams. & Y. Li sp. nov.

Fig. 2

Etymology.

Refers to the host genus, Clematis .

Description.

Saprobic on dried branches of Clematis species. Sexual morph: Ascomata 150-230 × 120-150 μm (x - = 176 × 138 μm, n = 5), solitary, scattered or aggregated in small groups, immersed to erumpent, subglobose, elongated, black, without a distinct ostiole. Peridium 10-20 μm wide at the base, 15-20 μm wide at the sides, comprising thick-walled cells of textura angularis, dark brown to black. Hamathecium comprising numerous, 1-3.5 μm wide (x -= 2.0 μm, n = 20), filamentous, septate, rarely branched pseudoparaphyses, hyaline, embedded in a gelatinous matrix, extending above the asci. Asci 114-174 × 27-43 μm (x - = 140 × 34 μm, n = 20), 8-spored, bitunicate, fissitunicate, cylindrical-clavate, short pedicellate, apically rounded, with an ocular chamber. Ascospores 22-39 × 8-21 μm (x - = 30 × 14 μm, n = 40), 1-2-seriate, partially overlapping, broadly fusiform, initially 3-septate and yellowish, becoming brown, verrucose or echinulate wall, muriform, with 3 transversely septa and a vertical septum in second and third cells, constricted at the septa, with obtuse ends, smooth-walled, surrounded by a thick mucilaginous sheath. Asexual morph: Undetermined.

Culture characteristics.

Colonies on PDA reaching 40 mm diam. after three weeks at 25 °C. Cultures from above, circular, flat to umbonate, covered with flocculent aerial mycelium, velvety on the surface, greenish-olivaceous, dense, entire edge; reverse black in the middle, green olivaceous radiating outwardly, white mycelium at the edge.

Material examined.

China. Yunnan Province, Kunming , on the dead aerial branch of Clematis sp. ( Ranunculaceae ), 24 April 2021, S. Tibpromma, S42, HMJAU 64844 (holotype); ex-type, CCMJ 13076; MFLU 23-0384 (isotype), ex-isotype, CCMJ 13077 .

Notes.

In the phylogenetic analyses, Comoclathris clematidis (CCMJ 13076 and CCMJ 13077) clustered with C. xanthoceratis (CCMJ 13078 and CCMJ 13079) with 82% ML and 100 BPP within Comoclathris (Fig. 1 ). Comoclathris clematidis was found on dried stems of Clematis species in the subtropical zone of Yunnan Province, China. The majority of Comoclathris species are found in temperate regions, but only C. incompta (CH-16) has been identified in subtropical regions ( Moral et al. 2017). Comoclathris clematidis differs from C. flammulae which was also found on Clematis by its larger asci (114-174 × 27-43 µm vs. 50-55 × 13-17 µm) and larger ascospores (22-39 × 8-21 µm vs. 16-22 × 10-16 µm). In addition, C. clematidis contains fewer transverse septa in ascospores (3 transverse septa vs. 6 transverse septa) ( Brahmanage et al. 2020). The new species Comoclathris clematidis is distinguishable from Comoclathris sedi which was also isolated from Clematis by having larger asci (114-174 × 27-43 µm vs. 80-110 × 16-18 µm), larger ascospores (22-39 × 8-21 µm vs. 19-20 × 8-10 µm) and fewer ascospore septa (3 transverse septa vs. 4-5 transverse septa) ( Ariyawansa et al. 2015). The ascomata of C. clematidis are immersed to superficial and appear as black spots or convex surfaces, while the ascomata of C. xanthoceratis are immersed to semi-immersed and covered with dark brown setae. Comoclathris clematidis has cylindrical-clavate asci and verrucose or echinulate ascospore walls, while C. xanthoceratis has clavate asci and smooth-walled ascospores. Both C. clematidis and C. xanthoceratis have ascospores with 3 transverse septa and 2 vertical septa. In addition, the two species show different culture characteristics and only C. xanthoceratis produce ascocarps in the culture. The ITS and rpb 2 base pair differences between the two species are 0.95% (5/526, no gaps) and 4.69% (34/725, no gaps), respectively.

In the BLASTn search, the rpb 2 sequence was 89.53% similar to Comoclathris arrhenatheri (MFLUCC 15-0465) with 100% query cover, translating to 89.53% similarity. The LSU sequence was 98.76% similar to C. permunda (CBS: 127967) with 99% query cover, translating to 97.77% similarity, while the SSU sequence was 98.58% similar to C. lini (MFLUCC 14-0968) with 100% query cover, translating to 98.58% similarity. The ITS region was 97.93% similar to Comoclathris sp. (14APR) with 93% query cover, translating to 91.07% similarity. Therefore, Comoclathris clematidis was introduced as a novel species.

Figures

Figure 1. The Bayesian 50 % majority-rule consensus phylogram, based on a concatenated ITS, LSU, SSU and rpb 2 dataset of Comoclathris. The tree is rooted with Neocamarosporium betae (CBS 523.66) and N. calvescens (CBS 246.79). RAxML bootstrap support values ≥ 70 % (ML, left) and Bayesian posterior probabilities ≥ 0.90 (BPP, right) are shown near the nodes. The new isolates are indicated in orange. The type strains are in bold and labelled with T.

Figure 2. Comoclathris clematidis (HMJAU 64844, holotype) A, B appearance of ascomata on host substrate C vertical section of ascoma D peridium E pseudoparaphyses F-H asci I-O ascospores P, Q culture characteristics on PDA after three weeks at 25 ° C. Scale bars: 200 µm (B); 50 µm (C); 20 µm (E-H, O); 10 µm (D, I-N).