Bambusicola hongheensis Phookamsak, Bhat & Hongsanan, 2024

Phookamsak, Rungtiwa, Hongsanan, Sinang, Bhat, Darbhe Jayarama, Wanasinghe, Dhanushka N., Promputtha, Itthayakorn, Suwannarach, Nakarin, Kumla, Jaturong, Xie, Ning, Dawoud, Turki M., Mortimer, Peter E., Xu, Jianchu & Lumyong, Saisamorn, 2024, Exploring ascomycete diversity in Yunnan II: Introducing three novel species in the suborder Massarineae (Dothideomycetes, Pleosporales) from fern and grasses, MycoKeys 104, pp. 9-50 : 9

Bambusicola hongheensis Phookamsak, Bhat & Hongsanan sp. nov.

Fig. 4

Etymology.

The specific epithet " hongheensis " refers to the locality, Honghe Hani and Yi Autonomous Prefecture (Yunnan, China), where the holotype was collected.

Holotype.

KUN-HKAS 129042.

Description.

Saprobic on dead culm of bamboo in terrestrial habitats, visible as black, shiny, gnarled on the host surface. Sexual morph: Ascomata 225-350 μm high, 340-590 μm diam., scattered, sometimes forming stroma with a clustered 1-3 ascomata, gregarious, semi-immersed, raised, becoming superficial, dark brown, dome-shaped to subconical or subglobose, glabrous, coriaceous, ostiolate with inconspicuous papilla. Peridium 40-80(-130) μm wide at sides towards the apex, 10-25 μm wide at the base, composed of several layers of small, dark brown pseudoparenchymatous cells, outer layer fused with host cells, arranged in textura angularis to textura globulosa, inner layer composed of 1-3 strata of flattened cells, of textura globulosa to textura prismatica, with thick, palisade-like cells at the sides. Hamathecium composed of 1-3 μm wide, filiform, dense, septate, branched, pseudoparaphyses, anastomosed between and above the asci, embedded in a gelatinous matrix. Asci (58-)70-90(-105)(-119) × 12-15(-17) μm (x̄ = 80.5 × 13.5 μm, SD = ± 13.2 × 1.8, n = 25), 8-spored, bitunicate, fissitunicate, cylindrical-clavate, shortly pedicellate, apically rounded with well-developed ocular chamber. Ascospores 22-26(-30) × 4.5-7 μm (x̄ = 24.6 × 5.4 μm, SD = ± 2.3 × 0.5, n = 30), overlapping 1-3-seriate, hyaline, fusiform, slightly curved, 1-septate, occasionally 2-3-septate, slightly constricted at the septum, the upper cell slightly larger than the lower cell, smooth-walled, surrounded by a thin, indistinct, mucilaginous sheath. Asexual morph: Undetermined.

Distribution.

China (Yunnan).

Specimen examined.

China. Yunnan Province: Honghe Hani and Yi Autonomous Prefecture, Honghe County, rice terraces, on dead culm of bamboo, 26 Jan 2021, R. Phookamsak BN06 (KUN-HKAS 129042, holotype). Notes: As the axenic culture is not active, the sequences of SSU and rpb2 were obtained from genomic DNA extracted from ascomata and dried culture.

Notes.

Based on the NCBI nucleotide BLAST search of ITS sequence, Bambusicola hongheensis (KUN-HKAS 129042) has the closest match with B. triseptatispora (MFLUCC 11-0166, ex-type strain) with 98.71% similarity (Identities = 535/542 with no gap) and is similar to B. loculata (MFLU 15-0056, ex-type strain) with 98.69% similarity (Identities = 528/535 with 1 gap) and B. splendida (MFLUCC 11-0611) with 98.25% similarity (Identities = 392/399 with no gap). The NCBI nucleotide BLAST search of LSU sequence indicated that B. hongheensis has the closest match with B. triseptatispora (MFLUCC 11-0166, ex-type strain) and B. didymospora (MFLUCC 10-0557, ex-type strain) with 100% similarity (Identities = 802/802 with no gap) and is similar to B. loculata (MFLU 15-0056, ex-type strain) with 99.75% similarity (Identities = 813/815 with 2 gaps) and B. nanensis (MFLUCC 21-0063, ex-type strain) with 99.49% similarity (Identities = 785/789 with no gap). The NCBI nucleotide BLAST search of rpb2 sequence indicated that B. hongheensis has the closest match with B. loculata (MFLU 15-0056, ex-type strain) with 99.90% similarity (Identities = 1042/1043 with no gaps) and is also similar to B. triseptatispora (MFLUCC 11-0166, ex-type strain) with 97.92% similarity (Identities = 990/1011 with no gap) and B. massarinia (voucher MFLU 11-0389) with 93.57% similarity (Identities = 975/1042 with 4 gaps).

Phylogenetic analyses of a concatenated ITS, LSU, rpb2, SSU and tef1-α sequence dataset demonstrated that Bambusicola hongheensis formed a separate branch (85% ML, 1.00 PP; Fig. 1 ), and clustered with B. loculata and B. triseptatispora with high support (100% ML, 1.00 PP; Fig. 1 ) and also clustered with the generic type of Bambusicola , B. massarinia with significant support (73% ML, 0.99 PP; Fig. 1 ). A nucleotide pairwise comparison of ITS sequence indicated that B. hongheensis differs from B. triseptatispora in 35/600 bp (5.83%), differs from B. loculata in 16/547 bp (2.92%) and differs from B. massarinia in 72/608 bp (11.84%). Whereas the nucleotide pairwise comparison of LSU sequence indicated that B. hongheensis is consistent with B. triseptatispora (0/802 bp) and B. loculata (1/816 bp), but differs from B. massarinia in 7/803 bp (0.87%). Furthermore, the nucleotide pairwise comparison of rpb2 sequence indicated B. hongheensis is not significantly different from B. loculata (1/1043 bp), but differs from B. triseptatispora in 21/1012 bp (2.07%) and differs from B. massarinia in 68/1042 bp (6.52%).

Morphologically, Bambusicola hongheensis resembles B. loculata and B. triseptatispora in terms of the size range of ascomata, asci and ascospores. However, B. hongheensis has comparatively smaller ascomata (340-590 μm diam. of B. hongheensis vs. 350-600 μm diam. of B. loculata vs. 470-730 μm diam. of B. triseptatispora ), shorter and wider asci ((58-)70-90(-105)(-119) × 12-15(-17) μm vs. 80-105 × 8-13 μm vs. (78-)80-100(-110) × 10-12(-14) μm, respectively) and sharing the size range of ascospores (22-26(-30) × 4.5-7 μm vs. 22-26.5 × 5-6 μm vs. (25-)26-30(-31) × 4-6 μm, respectively). The ascospores of B. hongheensis are typically hyaline, 1-septate, whereas B. triseptatispora has hyaline to pale brown and 3-septate ascospores ( Dai et al. 2017). Distinguishing B. loculata from B. hongheensis , based on morphological characteristics alone is challenging, but B. loculata can be differentiated by its larger ascomata and asci ( Dai et al. 2015). However, a clear differentiation is achieved through phylogenetic evidence (Fig. 2 ) and nucleotide pairwise comparison of ITS gene region (2.92% difference).

Figures

Figure 1. Phylogram of the best-scoring ML consensus tree of taxa in Bambusicolaceae and Occultibambusaceae. The new isolate is indicated in blue. Isolates from type materials are in bold. The ML ultrafast bootstrap and Bayesian PP values greater than 60 % and 0.90 are shown at the nodes.

Figure 2. Phylogram of the best-scoring ML consensus tree of Trichobotrys species in Dictyosporiaceae and closely-related families viz. Didymosphaeriaceae, Lentitheciaceae, Morosphaeriaceae, Sulcatisporaceae and Trematosphaeriaceae. The new isolate is indicated in blue. Isolates from type materials are in bold. The ML ultrafast bootstrap and Bayesian PP values greater than 70 % and 0.95 are shown at the nodes.

Figure 4. Bambusicola hongheensis (KUN-HKAS 129042, holotype) A the appearance of ascomata on the host surface B vertical section of an ascoma C, D peridia E pseudoparaphyses F, G asci embedded in pseudoparaphyses H-K ascospores L, M ascospores stained in India Ink show a thin mucilaginous sheath surrounding ascospores. Scale bars: 100 μm (B); 20 μm (C-G); 10 μm (H-M).