Fuscocatenula Reblova & A.N. Mill., 2021

Reblova, Martina, Nekvindova, Jana & Miller, Andrew N., 2021, Phylogeny and taxonomy of Catenularia and similar fungi with catenate conidia, MycoKeys 81, pp. 1-44 : 1

Fuscocatenula Reblova & A.N. Mill. gen. nov.

Etymology.

Fuscus (L) dark, brown, dusky, catenula (L), a little chain, referring to pigmented conidia in chains.

Type species.

Fuscocatenula submersa (Z.L. Luo, K.D. Hyde & H.Y. Su) Réblová & A.N. Mill.

Description.

Colonies effuse, hairy, brown, mycelium partly immersed, partly superficial. Anamorph. Conidiophores macronematous, mononematous, solitary, erect, unbranched, brown to dark brown, thick-walled, paler and thinner-walled towards the apex. Conidiogenous cells integrated, terminal, monophialidic, extending percurrently, cylindrical to lageniform, brown; collarettes funnel-shaped, brown. Conidia cuneiform to obovoid, broadly rounded apically, truncate at the base, aseptate, hyaline when young, pale brown at maturity, with protracted maturation, smooth, formed in a basipetal chain. Teleomorph. Unknown. (Description partly adapted from Li et al. 2017; Luo et al. 2019).

Habitat and geographical distribution.

Members of the genus are saprobes on decaying plant matter in terrestrial and freshwater environments, known only in Asia in China.

Notes.

Fuscocatenula is proposed as a segregate genus for fungi distantly related from Catenularia (Fig. 2 ), although morphologically similar. Conidia of Fuscocatenula are obovoid with a truncate base, lack an angular outline and small, circular, thin-walled pale areas in corners that are present in Catenularia . Conidia have a protracted maturation; at first they are hyaline and only later become pale brown, while still attached in a chain. Sometimes the chain consists of hyaline conidia with only one or a few mature pigmented conidia ( Li et al. 2017: fig. 1; Luo et al. 2019: fig. 52). In Catenularia , conidia are also hyaline when young but mature soon and when released from the conidiogenous locus they are usually pigmented. Since Catenularia also includes species lacking capitate hyphae, this character alone is not reliable in the distinction of Fuscocatenula from Catenularia .

Two species are accepted in the genus. Li et al. (2017) introduced Catenularia variegata for a foliicolous species from China and Luo et al. (2019) described Chaetosphaeria submersa for a dematiaceous hyphomycete from submerged wood in Thailand. Both species are similar and reminiscent of Catenularia . In the phylogenetic analysis based on ITS-28S sequences, relationship of Ch. submersa and Catenularia was not supported. Molecular data of C. variegata are not available. Based on a detailed comparison of original descriptions and illustrations of both species we conclude that C. variegata is congeneric with Ch. submersa . Therefore, C. variegata is excluded from Catenularia and both species are transferred to the new genus Fuscocatenula .

Figures

Figure 2. A Phylogenetic analysis of the combined ITS and 28 S sequences of members of the Chaetosphaeriaceae. Species names given in bold are taxonomic novelties; T, E, I, N and P indicate ex-type, ex-epitype, ex-isotype, ex-neotype and ex-paratype strains; * holotype of Chaetosphaeria trianguloconidia; Catenularia cubensis fide Luo et al. (2019). Thickened branches indicate branch support with ML BS = 100 %, PP values = 1.0. Branch support of nodes ≥ 75 % ML BS and ≥ 0.95 PP is indicated above and below branches B phylogenetic analysis of ITS and 28 S of the Chaetosphaeriaceae (continued). For legend refer to (A). Abbreviation: p. p. after a genus name (pro parte).