Okane Izumi, Hsieh Huei-Mei, Ju Yu-Ming, Lin Chun-Ru, Huang Chun-Yun, Kuan I-Ching
Institute of Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305- 8577, Ibaraki, Japan.
Institute of Plant and Microbial Biology, Academia Sinica, Nankang, 11529, Taipei, Taiwan.
Bot Stud. 2025 Jan 17;66(1):4. doi: 10.1186/s40529-024-00447-7.
Fungus gardens of the termite Odontotermes formosanus, excavated from Iriomote Island, Okinawa Prefecture, Japan, were subsequently incubated under laboratory conditions. A Xylaria species emerging from these fungus gardens was initially identified as X. angulosa, a species originally described from North Sulawesi, Indonesia. The Iriomote fungus is now described as a distinct species, X. iriomotensis.
Xylaria iriomotensis is peculiar in producing the teleomorph in culture but lacking an anamorph. Cultures of X. angulosa were obtained from two Taiwan specimens, which agree with the holotype from BO and the isotypes from NY and WSP in their stromata being repeatedly dichotomously branched and possessing a black core. In contrast to X. iriomotensis, X. angulosa does not form the teleomorph in culture but a typical Xylaria anamorph with conidiophores densely arranged in palisades. The ITS sequence obtained from the WSP isotype shared high similarities with those two Taiwan specimens as well as an Indian specimen, reconfirming the latter three specimens as X. angulosa. These four specimens shared 98.28-99.66% similarities at ITS sequences among themselves but only 84.25-85.01% similarities with X. iriomotensis. Molecular phylogenetic studies based on sequences of multiple protein-coding loci indicate that, while X. iriomotensis is grouped with three soil-dwelling species of the X. guepini cluster, X. angulosa belongs to the X. nigripes cluster, which includes all known species capable of producing massive sclerotia.
Xylaria iriomotensis has the teleomorph known only in culture, remaining to be rediscovered in its natural habitat where the stromatal morphology may be somewhat varied. The geographic distribution of X. angulosa, previously known only in Indonesia, has been expanded to Taiwan and India. Xylaria angulosa grouping with the X. nigripes cluster in our phylogenetic analyses indicates its potential to form massive sclerotia within termite nests.
从日本冲绳县西表岛挖掘出的台湾白蚁菌圃，随后在实验室条件下进行培养。从这些菌圃中分离出的一种炭角菌最初被鉴定为角状炭角菌，该物种最初是在印度尼西亚北苏拉威西岛被描述的。现在将西表岛炭角菌描述为一个独特的物种，即西表炭角菌。
西表炭角菌的独特之处在于其在培养物中产生有性型，但缺乏无性型。从两个台湾标本中获得了角状炭角菌的培养物，它们的子座反复二叉分枝并具有黑色核心，这与来自BO的模式标本以及来自NY和WSP的等模式标本一致。与西表炭角菌不同，角状炭角菌在培养物中不形成有性型，而是形成典型的炭角菌无性型，分生孢子梗密集排列成栅栏状。从WSP等模式标本获得的ITS序列与这两个台湾标本以及一个印度标本具有高度相似性，再次确认后三个标本为角状炭角菌。这四个标本在ITS序列上彼此之间的相似性为98.28 - 99.66%，但与西表炭角菌的相似性仅为84.25 - 85.01%。基于多个蛋白质编码基因座序列的分子系统发育研究表明，虽然西表炭角菌与炭角菌属guepini簇的三种土壤栖息物种聚在一起，但角状炭角菌属于炭角菌属nigripes簇，该簇包括所有已知能够产生大量菌核的物种。
西表炭角菌的有性型仅在培养物中已知，有待在其自然栖息地中重新发现，在那里子座形态可能会有所不同。角状炭角菌的地理分布以前仅在印度尼西亚已知，现已扩展到台湾和印度。在我们的系统发育分析中，角状炭角菌与炭角菌属nigripes簇聚在一起，表明其有在白蚁巢内形成大量菌核的潜力。
