Tremella sairandhriana A. Thomas & T.K.A. Kumar, sp. nov.
Index Fungorum number: IF 844398; Mycobank number: MB 844398; Facesoffungi number: FoF11779; Fig. 192
Etymology: refers to the collection locality.
Holotype: ZGCAT89.
Diagnosis: The species is characterised by whitish, resupinate, cerebriform basidiomes, and clamped hyphidia, and conidial formation from sterigmata. This species differs from the closely related T. resupinata by their larger basidiomes, presence of hyphidia and conidia borne on sterigmata.
Basidiomes medium sized, 10–45 × 1.5–3.5 mm, soft gelatinous, resupinate, cerebriform, sessile, broadly attached, easy to separate from the substratum. Margin sometimes wavy, white to pale yellowish white when fresh and pale yellowish brown when dry. Spore print whitish.
Hymenium pale brown in water. Hyphidia 3–7 µm, branched, septate, thick-walled, with clamp connections. Basidia 27–35 × 26–27.5 µm, globose to subglobose, two to four celled, longitudinally, transversely (rare), or obliquely septate, thin-walled, guttulate, hyaline, with basal clamp connection. Basidioles clavate to obovoid. Sterigma 59–96 × 6.5–9 µm, sometimes with swollen tip (up to 11 µm), septate, branched, occasionally producing conidia. Conidia from sterigma 3–7×3–7 µm, globose, hyaline, smooth, thin-walled. Basidiospores 16–19×17–20 µm (Q =0.84–1 µm, Qm =0.96 µm), globose to subglobose, hyaline, thin-walled, smooth, guttulate, apiculate. Secondary spore production, and yeast cell formation from basidiospores observed. Yeast cells 3–7×3–7 µm, globose, subglobose, broadly ellipsoid. Vesicles 10.4–12.7×5.9–7.8 µm, ellipsoid, oval, thick-walled. Swollen cells absent. Tramal hyphae 2–5.5 µm wide, slightly thick- to thick-walled, branched, smooth, hyaline, frequently anastomosing, with clamp connections. Haustoria abundant on hyphidia and subhymenium, rarely branching, with basal clamp connection, sometimes with forked tip.
Habitat and distribution – On unidentified fungal host growing on dead and decaying wood log. Material examined: India, Kerala State, Palakkad District, Silent Valley National Park, 4 July 2019, A. Thomas, ZGCAT89 (holotype).
GenBank numbers – ITS=ON668075, LSU=ON668076.
Notes – Tremella sairandhriana is characterised by whitish, resupinate basidiomes, presence of hyphidia, globose to subglobose basidia, formation of condia from sterigmata, and rarely branching haustoria. Among the whitish Tremella members, T. sairandhriana show close similarity to T. resupinata in the resupinate nature of basidiomes and larger size of basidia and basidiospores. However, T. sairandhriana differs from T. resupinata in the following characters: relatively large basidiomes, branched, septate, thick-walled, clamped hyphidia, and conidial formation from sterigmata.
Tremella cheejenii has similarity with T. sairandhriana in its whitish cerebriform basidiomes, and in the formation of conidia from sterigmata. However, T. cheejenii has smaller basidiospores (5–10 µm) when compared to T. sairandhriana. Tremella latispora also have whitish basidiomes and are similar in morphology with T. sairandhriana, but T. latispora differs by their smaller basidia (17.2–24.0 µm) and basidiospores (10.1–11.8 µm, Fan et al. 2021).
In the molecular phylogenetic analysis, T. sairandhriana clusters with T. resupinata (Fig. 2), and is a sister clade to the T. fibulifera complex of Fan et al. (2021). Members of T. fibulifera complex are morphologically characterised by cerebriform whitish basidiome and abundant clamp connections (Fan et al. 2021). The resupinate nature of basidiome, and the larger sized basidia and basidiospores of T. sairandhriana and T. resupinata segregate them from the T. fibulifera complex.
Figure 1 – Tremella sairandhriana (ZGCAT89, holotype). A Basidiocarp. B Cross section in water. C-E Diferent septations in mature basidia. F Vesicle. G Haustoria. H Basidiospores, budding and germination via germ tube. I Hyphidia with basidia of different developmental stages. J Collapsed basidia (Arrow) and conidia from its sterigmata. K Septate sterigmata (Arrow). L Bifurcating sterigmata bearing basidiospores. Scale bars: A=10 mm, B=30 µm, C—L=10 µm.
Figure 2 – Phylogram generated from maximum likelihood analysis based on nITS and nLSU sequences. The dataset contained 92 representative accessions with 1583 characters including gaps. Cryptococcus depauperatus were used as outgroup (Malysheva et al. 2015). Type strains are in bold and newly generated sequence is in blue