The genus Neosulcatispora was established in 2015 for a single species, Neosulcatispora agaves, a coelomycetous fungus described from leaves of Agave vera-cruz on the Indian Ocean island of La Réunion. A second species, Neosulcatispora strelitziae, was added a year later from leaf spots of the bird-of-paradise plant Strelitzia nicolai in South Africa. The genus is characterized by flask-shaped fruiting bodies called pycnidial conidiomata, walls built from brown cells of a tissue type known as textura angularis, conidiogenous cells that produce spores phialidically, and pigmented spores marked with longitudinal striations. Despite these defining traits, the genus had remained poorly sampled, and its phylogenetic boundaries, host range and morphological variation had never been evaluated with extensive multilocus phylogeny.

The setting for the new discovery is ecologically distinctive. The dry-hot valleys of southwestern China experience high temperatures, pronounced seasonality, low precipitation during the dry season and strong solar radiation. The collection site in Honghe County sits at 762 meters above sea level within the Yuanjiang–Honghe dry-hot valley system, a landscape of deeply incised valleys, steep slopes and pronounced seasonal water limitation. The region has a tropical semi-arid valley climate, and the January 2026 collection date fell within the dry season, which generally extends from November to April. Natural vegetation in these valleys has a savanna-like appearance, with a predominantly herbaceous layer interspersed with drought-adapted shrubs and scattered trees. The landscape is ecologically fragile, marked by sparse vegetation cover, eroded and nutrient-poor soils and localized land degradation driven by steep terrain, concentrated seasonal rainfall and human disturbance.

Such environments may select for distinctive fungal communities, and recent surveys across Yunnan have repeatedly shown that underexplored habitats continue to yield fungal novelties, from bamboo and herbaceous plants to woody litter and cultivated hosts. A targeted survey of dead woody litter in the Honghe dry-hot valleys had already revealed substantial undocumented microfungal diversity. The new study extends that picture to xerophytic monocotyledonous hosts, demonstrating the value of habitat-focused fungal inventories in these harsh landscapes.

In the laboratory, the team examined the dead agave leaves under a stereomicroscope, photographed the dark conidiomata visible on the leaf surface, and performed single-conidial isolation by transferring individual spores onto potato dextrose agar. Type specimens, including the holotypes, were deposited in the Herbarium of Cryptogams at the Kunming Institute of Botany, and living cultures were placed in the institute’s culture collection, with the new taxa registered in MycoBank. Hand sections of the fruiting bodies were mounted in distilled water and measured for diameter, wall thickness and spore dimensions, while colony growth was recorded on potato dextrose agar at 25 degrees Celsius in the dark over 30 days.

The cultures themselves revealed further differences between the two species. Neosulcatispora agavicola colonies reached 20 millimeters in diameter after seven days, developed moderate aerial mycelium with an irregular margin and produced brown-black pigment when mature, sporulating after 30 days. Neosulcatispora hongheensis grew faster, reaching 30 millimeters in the same period, with a white surface, a golden brown reverse and the same brown-black pigment at maturity. In culture, both species formed stromatic conidiomata immersed to semi-immersed in the agar, and their spores in vitro were somewhat larger than those produced on the host, a reminder that morphological characters can vary with growth conditions.

The phylogenetic work was extensive. The researchers amplified and sequenced five genetic loci from each new isolate: the internal transcribed spacer region, the partial 28S large subunit rDNA, the partial 18S small subunit rDNA, the translation elongation factor 1-alpha gene and the RNA polymerase II second largest subunit gene. The combined dataset comprised 4,386 characters, including gaps, and covered 92 representatives of genera within the family Phaeosphaeriaceae, with two strains of Quixadomyces hongheensis from the family Parapyrenochaetaceae serving as the outgroup. Maximum likelihood analysis with RAxML and Bayesian inference with MrBayes produced congruent topologies for the focal lineages.

The results were unambiguous. All five new isolates resolved within the clade containing the type species Neosulcatispora agaves. Three isolates, assigned to the new species Neosulcatispora agavicola, formed a lineage with 100 percent maximum likelihood bootstrap support and a 0.99 Bayesian posterior probability. The two remaining isolates, assigned to Neosulcatispora hongheensis, formed another fully supported monophyletic lineage with 100 percent bootstrap support and a posterior probability of 1.00. The clade containing both new species and the type species received 86 percent bootstrap support and a posterior probability of 1.00. An additional analysis based on the ITS locus alone, run in IQ-TREE, confirmed the two new species as distinct lineages separated from Neosulcatispora agaves.

The two new species differ clearly from one another in both form and molecules. Neosulcatispora agavicola produces larger conidiomata, measuring 250 to 300 by 180 to 220 micrometers, and mature conidia with a single septum, measuring 7 to 10.5 by 4 to 6 micrometers. Neosulcatispora hongheensis has smaller conidiomata of 90 to 120 by 100 to 150 micrometers and mature conidia with three to four septa, measuring 7.5 to 10 by 3.8 to 6 micrometers. Pairwise comparisons between the two species revealed differences of 2 out of 846 base pairs in LSU, 20 out of 540 in ITS, 25 out of 873 in tef1 and 46 out of 891 in rpb2. Distinguishing Neosulcatispora agavicola from the type species proved harder on morphology alone, because their conidial dimensions overlap substantially; the case instead rests on molecular differences, including 12 nucleotide differences across 540 ITS positions when gap-containing positions were excluded, and the fact that the two species are not recovered as immediate sister taxa in the combined phylogeny.

One of the study’s most consequential findings concerns Neosulcatispora strelitziae. In the five-locus analysis, the ex-type strain of that species was not recovered within the clade containing the type species of Neosulcatispora; instead, it was placed elsewhere in Phaeosphaeriaceae, sister to Phaeosphaeria thysanolaenicola. This raises questions about whether the genus, as previously applied, is monophyletic, meaning a group containing all descendants of a common ancestor. The authors stopped short of any formal reassignment, noting that a dedicated analysis with broader sampling and complete locus coverage is required. They also caution that both Neosulcatispora agaves and Neosulcatispora strelitziae are represented only by ITS and LSU sequences, so their phylogenetic positions rest solely on ribosomal loci, and the current topology should be treated as a working hypothesis rather than a definitive resolution.

The occurrence of all three longitudinally striate species on Agave vera-cruz, one from La Réunion and two from southwestern China, is noteworthy, but the authors are careful about what it means. With so few records, the pattern is insufficient to demonstrate host specificity and may partly reflect limited collecting or host-sampling bias, so these fungi should not yet be regarded as Agave-associated specialists. Similarly, while studies of other filamentous fungi suggest spore surface ornamentation can influence hydrophobicity, adhesion and dispersal, no ultrastructural, chemical, wettability or adhesion data exist for Neosulcatispora, and no adaptive function can yet be assigned to its striations. What the discovery does establish is that the Honghe dry-hot valleys, with their harsh climate and fragile landscapes, remain a rich and understudied reservoir of undescribed fungal diversity, one that continued surveys integrating voucher specimens, living cultures and multilocus sequence data will be essential to document.

Subject of Research: Taxonomic description of two new Neosulcatispora fungal species associated with Agave vera-cruz in a dry-hot valley of Yunnan, China

Article Title: Taxonomic novelties of two Neosulcatispora species ( Pleosporales , Phaeosphaeriaceae ) associated with Agave vera-cruz plants in a dry-hot valley of Yunnan, China

Article References: Dissanayake, L. S., Phookamsak, R., Maharachchikumbura, S. S. N., Al-Sabri, A. E., Xu, J., & Wanasinghe, D. N. (2026). Taxonomic novelties of two Neosulcatispora species (Pleosporales, Phaeosphaeriaceae) associated with Agave vera-cruz plants in a dry-hot valley of Yunnan, China. MycoKeys, 142, 157-184. https://doi.org/10.3897/mycokeys.142.213343

Image Credits: AI Generated

DOI: 10.3897/mycokeys.142.213343

Keywords: Neosulcatispora, Phaeosphaeriaceae, Pleosporales, Agave vera-cruz, Yunnan, dry-hot valley, fungal taxonomy, new species, multilocus phylogeny, coelomycetes, Honghe County, saprobic fungi