Malbranchea parafilamentosa Guerra-Mateo, Cano & Gené, 2025

Malbranchea parafilamentosa Guerra-Mateo, Cano & Gené sp. nov.

Fig. 8 View Figure 8

Etymology.

Greek para - ( παρα -), to resemble, referring to the morphological similarity to the sexual and asexual morphs of M. filamentosa .

Type.

Spain • Catalonia, Mediterranean coast, Tarragona, Platja de la Arrabassada , 41°6'45"N, 1°16'51"E, from sediments at 27 m depth, March 2022, G. Quiroga-Jofre & D. Guerra-Mateo ( holotype CBS H- 25616 , ex-type FMR 20151 View Materials , CBS 152725 View Materials ) GoogleMaps .

Description.

Saprobic on marine sediments. Mycelium superficial and immersed, composed of hyaline, septate, branched, smooth-walled, 1.5–2 µm wide hyphae. Asexual morph with well-differentiated fertile hyphae, arising laterally from vegetative hyphae, branched, straight, sinuous, or contorted, forming intercalary and terminal arthroconidia randomly, 1.5–2 µm wide. Arthroconidia enteroarthric, 0–1 - septate, hyaline, smooth- and thin-walled, cylindrical to subcylindrical or T-shaped, 3.5–4.5 (– 7.5) × 1.5–2 µm; secession rhexolytic. Sexual morph heterothallic (observed in FMR 20151 × IHEM 28255 on OA). Gymnothecia superficial, surrounded by asexual fertile hyphae, single or aggregated, orange-brown, globose to subglobose, 200–310 µm diam. (excluding appendages); peridium composed of a conspicuous network of hyphae, septate, branched, hyaline to brownish orange, finely asperulate, thick-walled, cylindrical, 2.5–4 (– 4.5) µm wide, with short and long lateral appendages; short appendages arising at acute angles, spine-like, with subacute ends, orange-brown, finely asperulate, 14–25 (– 30) × 3–4 µm; long appendages arising from peridium at acute and subacute angles, unbranched, straight or curved, cylindrical, progressively tapering terminally, orange-brown, finely asperulate and thick-walled with a basal knuckle-joint towards the base, smooth terminally, with a rounded or subacute curved apex, 200–560 × 3–4 µm long. Asci 8 - spored, evanescent, irregularly disposed, globose to subglobose, 7 × 5–6 µm. Ascospores unicellular, pale yellow, yellow in mass, reticulate (reticulation regular with smooth polygonal meshes under SEM), thick-walled, subglobose, 3 × 2.5 µm.

Culture characteristics

(after 14 days at 25 ° C). Colonies on OA reaching 15–20 mm diam., flat, floccose, white (1 A 1), submerged towards periphery, margin fimbriate; reverse white (1 A 1). On PDA, 20–22 mm diam., umbonate, cottony, white (1 A 1), margin entire and diffuse; reverse orange-white (5 A 2) to white (1 A 1). On PYE, 25–27 mm diam., convoluted, slightly radially sulcate at periphery, cottony, white (1 A 1), margin entire; reverse uncolored. Diffusible pigment not observed in any of the media studied.

Additional specimens examined.

Belgium, Duffel, on bat fur ( Myotis daubentonii ), October 2018, C. Van den Eynde ( IHEM 28255 ).

Cardinal temperatures for growth.

Minimum 5 ° C ( 1 mm), optimum 25–30 ° C ( 22–25 mm), maximum 35 ° C ( 1 mm).

Habitat and geographic distribution.

Bat fur and marine sediment. Belgium and Spain.

Notes.

Malbranchea parafilamentosa represents an independent lineage related to M. thaxteri and M. filamentosa (Fig. 3 View Figure 3 ). The three species are characterized by the production of fertile hyphae that produce arthroconidia randomly. The morphological differences between their asexual morphs are subtle, but M. parafilamentosa shows conspicuously sinuous or contorted fertile hyphae, while in M. filamentosa , they are straight and rarely slightly sinuous ( Sigler et al. 2002; Rodríguez-Andrade et al. 2021). Their sexual morphs display gymnothecia with short and long appendages, subglobose asci, and reticulate, subglobose ascospores. Malbranchea parafilamentosa and M. filamentosa are characterized by being heterothallic and producing yellow mass ascospores. These species can be distinguished by the width of the peridial hyphae (2.5–4 (– 4.5) µm and 4.5–6 µm) and the length of the long peridial appendages (200–560 µm and 100–290 µm) ( Sigler et al. 2002). Although the lengths of the peridial appendages overlap between M. parafilamentosa and M. thaxteri (200–560 µm and 250–540 µm), the latter species is characterized by being homothallic and producing hyaline ascospores ( Kuehn 1955; Orr and Kuehn 1971).

Of note is that our phylogenetic analyses show that the strains CBS 198.92 and CBS 146932 (Figs 2 View Figure 2 , 3 View Figure 3 ), labeled as Malbranchea setosa and Malbranchea stricta , respectively, are genetically identical to M. filamentosa ( UAMH 4097 ) ( Sigler et al. 2002). However, the authors who sent the specimen to the CBS collection never formally described M. setosa , so this name should be deemed invalid, and M. stricta should be considered a synonym.