Bloxamia

Fungalpedia – Note 2872, Bloxamia

Citation when using this data: Wenping Wu & Yongzhao Diao. 2023 – Fungalpedia.

Index Fungorum, Facesoffungi, MycoBank, GenBank, Fig 1

Classification: Bloxamiaceae, Helotiales, Leotiomycetidae, Leotiomycetes, Pezizomycotina, Ascomycota, Fungi

=Endosporostilbe Subram., J. Indian bot. Soc. 37: 49, 1958.

Mycelium partly immersed and partly superficial, composed of pale brown to medium brown, smooth, septate and branched hyphae. Anamorph: Conidiomata synnematous or sporodochial, dark brown, composed of a basal parenchymatous stroma and the aggregated conidiophores. Conidiophores densely aggregated in a sporodochium or synnemata, erect, straight, cylindrical to clavate, septate, simple, subhyaline, pale brown to brown, smooth, terminating in a phialidic conidiogenous cell. Conidiogenous cells cylindrical to subcylindrical, subhyaline, pale brown to brown, smooth, with collarette not visibly differentiated from the venter. Conidia endogenous, extruded in short or long chains and aggregated in wet spore mass, cuboid or short-cylindrical, oblong, with truncated or flattened ends, straight, mostly hyaline, aseptate, smooth, often provided with basal marginal frill or rarely fringes of wall material. Teleomorph: Apothecia gregarious, sessile or nearly so, shallow cup-shaped, disc flat, bright sulphur-yellow, pale yellow, exterior paler and minutely smooth, tough. Asci cylindric or clavate, usually 8-spore, pore not blued by iodine. Paraphyses cylindrical, containing yellow oil drops. Ascospore biseriate, ellipsoid to elliptic-fusiform, hyaline, 1-septate (For teleomorph, adapted from Dennis 1968).

Ecology/substrate/host: Saprobe on dead branches, rotten wood.

Geographical distribution: Widely distributed worldwide.

Description and illustration: Pirozynski and Morgan-Jones (1968); Nag Raj and Kendrick (1975); Dennis (1968).

Notes: Bloxamia, typified by B. truncata, is characterized by its conidiophores densely aggregated in a black sporodochia or synnemata and arising from a basal thin parenchymatous stroma, cylindrical or clavate phialidic conidiogenous cells, and hyaline or pale-colored cuboid, short-cylindrical or oblong conidia in wet spore mass (Ellis 1971; Pirozynski and Morgan-Jones 1968; Nag Raj and Kendrick 1975; Aramarri et al. 1992). The conidiophores are macronematous, erect, cylindrical, septate, sparsely branched, subhyaline, pale brown or brown, forming a palisade over the stroma and terminating in phialides. The conidiogenous cells are phialidic, cylindrical, subcylindrical or clavate, with a deep collarette extending from undifferentiated venter. The conidia are endogenously differentiated, short-cylindrical to cuboid, oblong with truncate ends, and unicellular, hyaline to subhyaline (Nag Raj and Kendrick 1975). It shares its enteroblastic-phialidic mode of conidial ontogeny with Chalara and Sporoschisma, but is distinct in its sporodochia or synnemata, and the invisibly differentiated phialides. Bloxamiaceae Locq. Was created by Locquin (1984) and validated by Hernández-Restrepo et al. (2017) for Bloxamia truncata Berk. & Broome. However, the phylogenetic analyses showed that the genus Bloxamia was a member of Pezizellaceae (Johnston et al. 2019).

The species assigned to this genus include: B. bohemica, B. cremea, B. cyatheicola, B. foliicola, B. hesterae, B. nilagirica, B. santae–insulae and B. truncata (Nag Raj and Kendrick 1975; Aramarri et al. 1992; Liu and Zhang 1998; Coppins and Minter 1981; Minter and Holubová-Jechová 1981; Seifert et al. 2011; Spooren 2014; Guatimosim et al. 2016). Morphologically these species can be difficult to be distinguished, since limited morphological characters, including conidiogenous cells and conidia, can be used for identification (Lizon and Korf 1995). Several connections were established between the asexually typified genus Bloxamia and sexually typifie species, such as Calycina claroflava, C. discedens and C. sulfurina (Berthet 1964; Carpenter 1975; Johnston 1988; Lizon and Korf 1995; Gamundí and Giaiotti, 1998; Zhuang and Hyde 2001; Hosoya et al. 2011; Hosoya and Zhao 2016 ; Mitchell et al. 2022). Berthet (1964) reported a Bloxamia anamorph in culture from single ascospore isolations of Calycina sulfurina. Carpenter (1975) and Johnston (1988) reported a Bloxamia anamorph for Calycina discedens, where the anamorph was found on host tissue in association with the teleomorph, on the sides of the apothecia, and was also produced in culture from single ascospore. The two species, Calycina claroflava and C. sulfurina can hardly be distinguished from each other based on morphology (Johnston 1988). Guatimosim et al. (2016) described both anamorph and teleomorph under Bloxamia cyatheicola as a leaf pathogen of fern from Brazil.

In a recent study Mitchell et al. (2022) showed that species of Bisporella should be reassigned to at least four genera, and the species with chalara-like anamorphs such as B. claroflava and B. discedens were assigned to Calycina with broad concept. However, the phylogenetic analyses with different datasets of the integrated LSU/SSU and LSU/ITS sequences in this study showed that the genus Calycina was polyphyletic, and the analyzed species scattered in different subclades under the well-supported Calycina/Chalara clade. In the phylogenetic tree of Pezizellaceae, the 13 species of Calycina scattered in at least 3 subclades under Calycina/Chalara s. str. clade: the first one consisted of C. herbarum (the type species), C. alstrupii, C. discreta, C. languida, C. lactea, C. populina, C. vulgaris, and 6 chalara-like species, the second one consisted of C. cortegadensis, C. marina, C. claroflava, C. sulfurina and three Bloxamia species, and the last one consisted of C. citrina and C. shangrilana. Similar results were also presented by other researchers (Baral and Rämä 2015; Guatimosim et al. 2016; Friggens et al. 2017; Suija and Motiejūnaité 2016; Crous et al. 2019; Karunarathna et al. 2021; Mitchell et al. 2022). Within the second subclade consisting of Bloxamia truncata, C. cortegadensis, C. marina, C. claroflava, C. sulfurina and two other Bloxamia species, all species with Bloxamia anamorphs were nested together as one strongly supported clade (100 bs/1 pp). The similar result was obtained from another analysis by using the integrated LSU and ITS dataset of Calycina and Chalara. For this reason, the genus Bloxamia is accepted as a separate genus, although they are closely related to Calycina. This result was well supported by other works (Karunarathna et al. 2021; Mitchell et al. 2022). In the phylogenetic tree provided by Karunarathna et al. (2021), C. discedens and C. sulfurina clustered together as a strong supported subclade (99 bs/ 1 pp) distinct from other Calycina species. Mitchell et al. (2022) showed that B. truncata and C. claroflava clustered together, although the authors adapted a broad concept of Calycina. Biologically, most of the described Bloxamia species were saprophytic fungi on dead branches, rotten needles and woods. However, B. foliicola was reported as plant pathogens causing leaf spot disease (Liu and Zhang 1998). Bloxamia foliicola and B. nilagirica were recorded in China, however no strain could be found

for molecular phylogenetic study.

Type species: Bloxamia truncata Berk. & Broome, Ann. Mag. nat. Hist., Ser. 2 13: 468 (1854)

Other accepted species: Species Fungorum – search Bloxamia.

Figure 1 – Bloxamia truncata (Wu8259b). a Basal stroma and conidiophores of a sporodochial conidiomata. b, c, f Conidiophores and cylindrical phialidic conidiogenous cells. d, e Conidia. Scale bar: 10 μm for a, 5 μm for b–f.