Scedosporium dehoogii Gilgado, Cano, Gene´ Guarro in Journal of Clinical Microbiology 46: 2 (2008).

Index Fungorum number: IF 538388; MycoBank number: MB 538388; Facesoffungi number: FoF 04829; Fig. 1, 2

Saprobic on decaying woody of Avicennia marina. Asexual morph: Colonies effuse, light brown. Mycelium mostly immersed, composed of septate, branched, smooth, pale brown to hyaline hyphae. Synnemata solitary to gregarious, erect, dark brown, 190–390 µm tall with a cylindrical stipe from 10 to 30 µm wide (x̄ =242×16 µm, n=10), dark gray, smooth-walled, terminated into a slimy head of conidia, slimy head 45–75 µm long, 55–80 µm wide (x̄ =60×64 µm, n=10). Hyphae interwoven at the base, unbranched in the stipe, branched at the apex to form conidiophores. Conidiophores synnematous, solitary, branched, often reduced to conidiogenous cells which were subhyaline. Conidiogenous cells terminal or lateral, hyaline, smooth-walled, cylindrical to slightly flask-shaped, 25–40×2–3 µm (x̄ =31×2.5 µm, n=10). Conidiogenous cells arise from undifferentiated hyphae, cylindrical to slightly flask-shaped, producing slimy heads of one-celled, smooth-walled, sub-hyaline, obovoid or sub-cylindrical conidia. Conidia: two types of conidia: (i) those produced on synnemata and solitary conidiophores were predominantly cylindrical or claviform, hyaline, 5–10×2–3 µm (x̄ =7.3×2.7 µm, n=20) with a wide truncate base; (ii) those developed mainly from the undifferentiated hyphae of the substrate were sessile or on short protrusions, solitary, lateral, brown, smooth, and thick-walled, mostly obovoid 2.5–7.5×2–3 µm (x̄ =4.3×2.4 µm, n=20). Sexual morph: Not observed.

Culture characteristics – Conidia germinating on Sea Water agar within 24 h. Germ tubes produced from the conidial base. Colonies on PDA fast growing, attaining 40–45 mm diameter after 14 days at 25 °C, circular, raised, with white to grey at centre and white to cream at margins, cottony; pale yellow in reverse with entire margin. The optimum growth temperature was from 25 to 37 °C. The fungus did not grow at 45 °C. Hyphae hyaline to pale brown, branched and septate, 1–3 µm wide. Conidiophores synemmatous; synnemata solitary to gregarious, erect, dark brown, 180–255 µm tall with a cylindrical stipe from 10–30 µm wide (x̄ =223×17 µm, n=10), dark gray, smooth walled, terminating into a slimy head of conidia, 45–85 µm long and 55–90 µm wide (x̄ =63×66 µm, n=10). Hyphae interwoven at the base, unbranched in the stipe, branching at the apex to form conidiophores. Conidiophores solitary, branched often reduced to conidiogenous cells which were sub-hyaline.
Conidiogenous cells terminal or lateral, hyaline smooth-walled, cylindrical to slightly flask-shaped, 30–45×2–3 µm (x̄ =35×2.4 µm, n=10). Conidiogenous cells arising from undifferentiated hyphae, cylindrical to slightly flask-shaped, producing slimy heads of one-celled, smooth-walled, sub hyaline, obovoid or sub-cylindrical conidia. Conidia: two types: (i) those produced on synnemata and solitary conidiophores, predominantly cylindrical or claviform, hyaline, 5–15×2–5 µm (x̄ =10×3 µm, n=20) with a wide truncate base; (ii) those developed mainly from the undifferentiated hyphae of the substrate were sessile or on short protrusions, solitary, lateral, brown, smooth, and thick-walled, mostly obovoid 2.5–9×2–5 µm (x̄ =5×3.5 µm, n=20).

Material examined – India, Tamil Nadu, Tiruvarur, Muthupet mangroves (10.4° N 79.5° E), on decaying wood of Avicennia marina (Forssk.) Vierh. (Acanthaceae), 28 November 2015, B. Devadatha (AMH 9945), living culture, NFCCI- 4274.

Hosts – Agricultural areas, playgrounds, riverbanks, Soil, Human infections (Rougeron et al. 2018)

Distribution – Australia, Austria, Chile, India, Netherlands, Spain, Thailand (Rougeron et al. 2018)

GenBank numbers – MH569493 (ITS), MH569492 (LSU), MH571777 (SSU)

Notes – Multigene phylogenetic analyses of combined datasets of ITS sequence data revealed that Scedosporium dehoogii (NFCCI-4274) clustered together with the type and other existing strains of S. dehoogii with moderate statistical 74% ML and 78% MP support (Fig. 2). Scedosporium dehoogii (NFCCI-4274) from decaying wood of Suaeda monoica and Avicennia marina and colonies on PDA also share similar morphological characteristics with S. dehoogii (CBS-117406) reported from the soil (Gilgado et al. 2008). Scedosporium dehoogii is a common environmental species occurs on locations with high human activities like soil, water, agricultural areas and not involved in human infections (Kaltseis et al. 2009). However, this is the first report of Scedosporium dehoogii (NFCCI- 4274) from marine habitats. Earlier Medicopsis romeroi has been reported from mangroves (Devadatha et al. 2020). Also, Calabon et al. (2018) reported S. aurantiacum from Sponges in mangroves. With the present two species from mangroves totally three Scedosporium spp. are recorded from marine environments (Figs. 2, 3).

Figure 1 – Scedosporium dehoogii (AMH 9945, new record) a Colonies on decaying woody stem of Suaeda monoica. b−c Synnemata. d−f Slimy head and conidiophores. g−h Conidiogenous cells with annellidic conidia. j Cylindrical and obovoid conidia. Scale bars: b=50 µm c=100 µm, d−j=10 µm

Figure 2 – Scedosporium dehoogii (NFCCI- 4274) a−b Cultures on PDA after 14 days. c−d Synnemata. e Slimy head and Conidiophores. f sessile obovoid conidia. g Conidiogenous cells with annellidic conidia. h. sub cylindrical conidia i−n Cylindrical and obovoid conidia and Scale bars: c=50 µm d−n=10 µm

Figure 3 – Phylogram based on the RAxML analysis of a combined ITSrDNA and tub2 sequence dataset. Bootstrap support values for ML and MP higher than 70% values are given above each branch respectively. The new isolates are represented in blue. The tree is rooted to Parascedosporium sanyaense EM65901. Thirty-eight sequences are included in the phylogenetic analyses with 1159 characters including gaps. The maximum parsimonious dataset consisted of 855 characters were constant, 166 parsimony-informative and 138 parsimony-uninformative. The parsimony analysis of the data matrix resulted in Two hundred and seventy equally parsimonious trees with a length of 486 steps (CI=0.759, RI=0.888, RC=0.674, HI=0.241)