First record of Inosperma subsphaerosporum (Inocybaceae) in Indonesia

Abstract

Inosperma (Inocybaceae) was originally described as a subgenus of Inocybe. Some species of Inosperma are considered edible mushrooms, but this genus also includes a few toxic species with high levels of muscarine. To date, the knowledge of this genus in Indonesia remains poor. During a mushroom hunting in Central Kalimantan (Indonesia) by the Indonesian mushroom hunter community, some fruiting bodies of inocyboid fungi which consumed and traded by the local people were collected. At glance, the specimens resembled Inosperma or Pseudosperma by the macromorphological characters in the field. Our goal was to justify the taxonomical position of our inocyboid specimens based on morphological and molecular evidence. The fresh fruiting bodies were used for the analysis. The basidiomata was described based on the macro- and micromorphological characters. The molecular analysis and phylogenetic tree construction were performed based on ITS 1–2 sequences. The combination of morphological and molecular analyses confirmed our collection as Inosperma subsphaerosporum. Morphologically, our specimens can be determined by the conical applanate cap with umbo, incurved to decurved margin, dry pileus with fibrillose to rimulose surface, lamellae adnexed to sinuate, cylindrical stipe, subglobose to globose smooth basidiospores, and abundant cheilocystidia in clusters. The yellow intracellular contents of cheilocystidia distinguished our specimen from Pseudosperma, while the outline of basidiospores differed our specimens to closely morphological species of I. carnosibulbosum, I. akirnum, and I. saragum. The BLAST result revealed that our specimen exhibits 96 % similarity to I. subsphaerosporum as the top hit. The phylogenetic tree (RAxML) nested our specimens in the I. subsphaerosporumclade from type material. The current study provides the first information on the occurrence of I. subsphaerosporum in Indonesia. Future study should be done to analyze both nutritional and muscarine content of this Indonesian Inosperma.