Naematelia encephaloidea A. Thomas & T.K.A. Kumar

Thomas, Anjitha & Kumar, T. K. Arun, 2024, A new species of Naematelia (Tremellales, Basidiomycota) from India, Phytotaxa 646 (1), pp. 58-66 : 61-64

Naematelia encephaloidea A. Thomas & T.K.A. Kumar , sp. nov. FIGURE 1 , 2 .

MycoBank: MB850672

Etymology:—refers to the morphological resemblance with basidiocarps of the closely related species, N. encephala .

Diagnosis:— Naematalia encephaloidea is characterized by the presence of cream to yellowish brown, cerebriform basidiocarp, with a whitish inner core composed of host hyphae; thick-walled, non-germinating swollen cells, and thin-walled, germinating swollen cells; thick-walled, globose, conidia formation from tramal hyphae; inflated cells in the trama; and lack of hyphidia. Species is parasitic on Stereum species. Compared to the morphologically similar N. aurantialba , N. encephaloidea has smaller basidiocarps (5–53 × 4–40 mm), basidiospores (6.5–9 × 5–7 µm) and basidia (11–16 × 10–13 µm). Naematelia encephaloidea differs from N. encephala by a partially hollow inner core of the basidiocarp and a different host species. Phylogenetically, N. encephaloidea is distinct.

Holotype:— INDIA, Kerala State, Palakkad District, Silent Valley National Park, 24 June 2022, Anjitha Thomas , ZGCAT326 .

Description:—Basidiocarp 5–53 × 4–40 mm, medium-sized, firm gelatinous, cartilaginous, cerebriform, lobed, sessile, cream to yellowish brown, becoming paler with maturity, darkening on drying. Inner region partially composed of whitish host hyphae. Parasitic on an unidentified Stereum species.

Hymenium pale yellowish in water. Hyphidia not observed. Basidia 11–16 × 10–13 µm, subglobose to broadly ellipsoid, two to four-celled, longitudinally or obliquely septate, thin- to thick-walled, guttulate, hyaline. Basidioles subglobose to broadly ellipsoid. Sterigma 19–108 × 2–3 µm, slightly thick-walled, up to 5 µm towards tip. Basidiospores 6.2–9 × 5–7 µm (Q = 1.1–1.4 µm, Qm = 1.16 µm), globose to subglobose, broadly ellipsoid, obovoid, hyaline, thinto thick-walled, smooth, apiculate, guttulate. Direct germination and secondary spore formation observed. Tramal hyphae mixed with host hyphae, 2–5.5 µm wide, frequently inflated, slightly thick- to thick-walled, branched, smooth, guttulate, hyaline with clamp connections. Haustoria abundantly present throughout the trama, frequently branching, up to 5 haustorial hyphae from a haustorial cell, with basal clamp connection. Swollen cells are of two types. Type 1; 4–10 × 4–6 µm, globose, subglobose, ellipsoid, cylindrical, narrowly utriform, thick-walled, prominently guttulate, non germinating, with basal clamp connection, borne on hyphae. Type 1 swollen cells were abundant in the basidiocarp developing on the host ( Stereum ) basidiocarp and not observed in basidiocarp developing on the bark. Type 2; 4–12 × 3–5 µm, ellipsoid, lemoniform, oblong and clavate, sometimes with 3–8 µm long apical protuberances, thin-walled, guttulate, rarely germinating, commonly terminal. Type 2 swollen cells were rare in basidiocarp developing on the host ( Stereum ) basidiocarp and abundant in basidiocarp developing on the bark. Inflated cells 12–16 × 6–5 µm, versiform, thin-walled. Conidia 3–5 × 3–5 µm, globose, abundant, thick-walled, guttulate.

Habitat:—Mycoparasitic on Stereum species present on dead and decaying wood.

Additional specimen examined:— INDIA, Kerala State, Palakkad District, Silent Valley National Park, 24 June 2022, Anjitha Thomas, ZGCAT325. INDIA, Kerala State, Palakkad District, Silent Valley National Park, 24 June 2022, Anjitha Thomas, ZGCAT327. INDIA, Kerala State, Palakkad District, Silent Valley National Park, 24 June 2022, Anjitha Thomas, ZGCAT329.

Molecular phylogeny

The final aligned data matrix consisted of 56 taxa with 94 ITS and 78 LSU sequences representing 55 ingroup and one outgroup species. The ITS and LSU sequences of holotype showed 92.86% and 98.29% identity in the BLAST search analysis with N. encephala strain UCDFST 68-887.2 (GenBank accession number: OL739376 (combined SSU, ITS, LSU sequence). All the six sequences generated from N. encephaloidea clustered independently with high bootstrap support value. The Naematelia clade contained five species, including N. encephaloidea . The new species is related to N. aurantialba and N. encephala in the phylogenetic tree.

Discussion

The newly proposed species perfectly fits within the genus concept of Naematelia , both morphologically and phylogenetically. The morphological features like cerebriform shape, cream to yellowish brown color; parasitizing nature on Stereum species; presence of host hyphae as reticulate patches in the inner core region; subglobose to broadly ellipsoid basidia and globose to subglobose basidiospores are conspecific with other Naematelia members ( Bandoni & Zang 1990, Chen 1998). In the phylogenetic tree generated using ITS and LSU sequences ( FIGURE 3 .), N. encephaloidea clusters in between other Naematelia members.

Among the Naematelia members considered in the phylogenetic study, N. aurantia and N. microspora has foliose basidiocarp and, N. aurantialba , N. encephala and N. encephaloidea has cerebriform basidiocarps. The clustering of N. encephaloidea between N. aurantialba and N. encephala supports the evolutionary relationship of cerebriform members in the genus Naematelia .

Sequences of N. encephaloidea showed a close relationship with N. aurantialba and N. encephala in the BLAST search analysis and also in the molecular phylogenetic tree. When compared with N. aurantialba , N. encephaloidea has small-sized (5–53 × 4–40 mm) basidiocarps, smaller basidiospores (6.5–9 × 5–7 µm) and basidia (11–16 × 10–13 µm). Whereas, N. aurantialba has larger basidiocarp (60–170 × 35–110 mm), larger basidiospores (10–14 × 9–12.5 µm), and basidia (16–32 × 10–20 µm) ( Bandoni & Zang 1990). Morphologically, N. encephaloidea is similar to N. encephala in the basidiocarp size, shape, basidia, and basidiospore measurements. Naematelia encephala has a solid, non-gelatinous, whitish mass of host hyphae in the inner core of the basidiocarp ( Chen 1998), whereas N. encephaloidea has a partially hollow inner core of the basidiocarp. Naematelia encephala is associated with the host Stereum sanguinolentum ( Bandoni 1961, Roberts 1999, Hawksworth et al. 2016). Whereas, N. encephaloidea has a different host species.

Figures

FIGURE 1. A. Naematelia encephaloidea growing on the host basidiocarp (Dried specimen showing interior is given as inset); B. Naematelia encephaloidea growing on wood log (Dried specimen showing interior is given as inset). Scale bars: A,B=10mm.

FIGURE 2. Naematelia encephaloidea: A. Basidiospores; B. Basidiospore producing secondary spore; C. Hymenium with basidia of different developmental stages; D–E. Basidia; F–G. Haustoria and thick-walled swollen cells; H. Thick-walled swollen cells; I. Thinwalled swollen cells; J. Germinating thin-walled swollen cell; K. Trama with abundant thick-walled swollen cells and two inflated cells; L. Tramal hyphae with haustoria and host hyphae (arrow); M. Tramal hyphae with conidiospores; N. Conidiophore with conidiospores. Scale bars:A–N=10µm.

FIGURE 3. Maximum Likelihood tree generated from the combined ITS and LSU sequences. Bootstrap support values above 50 are indicated above branches. The new species is indicated in bold. Holotype is represented in red color. Cryptococcus depauperatus was set as the outgroup.