Xisha Islands are located in a low-latitude area that straddles the boundary between the Indian and eastern Asian monsoon systems. The unique and diverse ecosystem provides habitats for numerous microorganisms, generating exceptionally rich microbial resources. Due to the remote geographical locations of most islands and the fact that the coastal vegetation is in the vanguard stage of oligotrophic conditions, the microbial communities may differ from those of islands with complex vegetation. In this study, through the research on the fungal diversity of coastal coral sandy soil in Xisha Islands, two new species of Aspergillus, namely A. paraflavipes and A. ganquanensis, were isolated from the local coral sandy soil samples using potato-dextrose agar. Identifications of new species were carried out based on various methods such as detection of growth rate in plate culture, observation of colony morphology in plate growth, microscopic morphological comparison, and multi-gene combined phylogenetic analysis (ITS-BenA-CaM-RPB2). The results showed that the species exhibiedt taxonomic status and morphological characteristics that are different from those of existing species. By integrating various detection methods and comparison results, they could be regarded as new taxonomic units. A. paraflavipes and A. ganquanensis belonged to the genus Aspergillus, subgen. Circumdati in sect. Flavipedes and sect. Circumdati, respectively. According to the results of the combined phylogenetic analysis of multiple genes, A. paraflavipes in sect. Flavipedes was a separate lineage parallel to the ser. Flavipedes. According to its microscopic morphological structure, it is shown that the conidiomata of A. paraflavipes was very special, and the size of its stipes and vesicles was much smaller than that of other species in the sect. Flavipedes. According to the growth rate detection results, A. paraflavipes could grow at a relatively fast rate (21-24 mm, 7 days) on Czapek yeast autolysate (CYA) at 40 ℃. Among the ser. Flavipedes similar to A. paraflavipes, only A. ardalensis (growth rate ≤2 mm, 7 days) and A. templicola (4-8 mm, 7 days) could grow on CYA at 40 ℃. And its growth rate was extremely slow, and none of the other species grow. Based on the results of phylogenetic analysis, microscopic morphological observation and growth rate comparison, it is believed that A. paraflavipes is located in an undiscovered series in sect. Flavipedes. Therefore, we propose to establish a new strain, ser. Paraflavipedes, to accommodate A. paraflavipes. The detailed morphological comparison and the description of the identification results were described in the article. Multi-gene combined phylogenetic analysis showed A. ganquanensis presented a unique branch in the sect. Circumdati, ser. Sclerotiorum, showing similar morphology to those of the species in this series. This study isolated and documented two new species of Aspergillus originated from the Xisha Islands, expanding our understanding of the fungal diversity of the Xisha Islands. Moreover, it is particularly important to record the biodiversity of the ecosystem before human activities affecting it.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |