Biodiversity of the Indonesian marine sponge genus Aaptos with molecular networking approach

Abstract

Many natural products have been isolated from the cryptic species of the Indonesian marine sponge. Despite this, it remains unclear how sponges produce such a diverse array of metabolites and their relationship to sponge diversity. During our expedition in 2017-2019, we collected the Indonesian marine sponge of the genus Aaptos, which was found surrounding Weh and Aceh Islands, the northwesternmost part of the Indonesian archipelago. All specimens were subjected to a feature-based molecular networking approach to understand their relationship. The molecular phylogenetic clades of genus Aaptos were examined by cytochrome oxide I (COI) while the presence of their chemotypes were confirmed by chemical analysis based on bioassay-guided separation with several steps of chromatography. As results, the presence Aaptos suberitoides, Aaptos aaptos, Aaptos nigra, Aaptos lobata, and Aaptos sp. were confirmed by the molecular phylogenetic. On the other hand, chemical analysis showed the presence of alkaloid-class molecules on all specimens. Interestingly, feature-based molecular networking revealed the whole figure of cryptic species were formed a clear and distinct group together with their chemotypes. Consequently, it confirmed that the relationship between the presence of each species as well as its chemotype can be distinguished clearly. In conclusion, we suspect the chemical analysis of the genus Aaptos have unknowingly conflated between different cryptic species, resulting in the seemingly idiosyncratic chemical variations.