Scedosporium marina Devadatha & V.V Sarma, sp. nov.
Index Fungorum number: IF 558432; MycoBank number: MB 558432; Facesoffungi number: FoF 05035; Figs. 1, 2
Etymology – The specific epithet is in reference to the marine environment in which the fungus was collected.
Holotype – AMH-9946.
Saprobic on decaying woody stem of the halophyte Suaeda monoica. Asexual morph: Colonies effuse,
light brown. Mycelium immersed, composed of septate, branched, smooth, pale brown to hyaline hyphae. Synnemata solitary to gregarious, erect, dark brown, 170–1110 µm tall with a cylindrical stipe, 10–25 µm wide ( x̄ =642 × 16 µm, n=10), dark gray, smooth-walled, terminate into a slimy head of conidia, slimy head 60–140 µm long and 60–165 µm wide ( x̄ = 86 × 111 µm, n = 10). Hyphae interwoven at the base, unbranched in the stipe, branching at the apex to form conidiophores. Conidiophores synnematous, solitary, branched, often reduced to conidiogenous cells, growing laterally bearing a single verticil conidiogenous cell. Conidiogenous cells percurrent, terminal or lateral, hyaline, smooth-walled, cylindrical to slightly flask-shaped, 25–55×2–2.5 µm (x̄ =35×2.25 µm, n = 10). Conidiogenous cells arising from undifferentiated hyphae are cylindrical to slightly flask-shaped, producing slimy heads of one-celled, smooth-walled, sub hyaline, obovoid or sub-cylindrical conidia. Three types of conidia are produced: (i) those produced on solitary conidiophores sub hyaline, smooth-walled, obovoid, or sub cylindrical 7–13 × 2.5–5.5 µm (x̄ =10 × 4 µm, n=20); (ii) those produced on synnemata predominantly cylindrical or claviform, 5–13 × 1–3 µm (x̄ =9 × 2 µm, n=20) with a wide truncate base; (iii) those developed mainly from the undifferentiated hyphae of the substrate, sessile or on short protrusions, solitary, lateral, brown, smooth, and thick-walled, mostly obovoid 2.5–10×2–2.5 µm (x̄ =9×2.3 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 attaining 30–35 mm diameter after 14 days at 25 °C, circular, raised, light grayish at center and smoke gray at margins, cottony; yellow in reverse with entire margin. The optimum growth temperature was from 25 to 37 °C, and did not grow at 45 °C. Hyphae hyaline to pale brown, branched and septate, 3–7.5 µm wide. Synnemata developed after 30 days of incubation at 25 °C; synnemata solitary to gregarious, erect, dark brown, 190–1400 µm tall with a cylindrical stipe from 10 to 25 µm wide ( x̄ = 647 × 16.9 µm, n=10), dark gray, smooth-walled, terminated into a slimy head of conidia, 25–35 µm long and 35–50 µm wide (x̄ =30×36 µm, n=10). Conidiophores solitary, branched, often reduced to conidiogenous cells growing laterally bearing single verticil of conidiogenous cells. Conidiogenous cells terminal or lateral, hyaline, smooth-walled, cylindrical to slightly flask-shaped, 25–50 × 2–3 µm ( x̄ = 35 × 16 µm, n = 10). Conidiogenous cells arising from undifferentiated hyphae, cylindrical to slightly flaskshaped, producing slimy heads of one-celled, smooth-walled, sub-hyaline, obovoid or sub-cylindrical conidia. There were three types of conidia: (i) those produced on solitary conidiophores subhyaline, smooth-walled, obovoid or subcylindrical 5–10 × 1.5–3 µm (x̄ =6.8 × 2.3 µm, n = 20); (ii) those produced on synnemata predominantly cylindrical or claviform, 7.5–10 × 2–3 µm (x̄ =8.7 × 2.4 µm, n=20) with a wide truncate base; (iii) those developing mainly from the undifferentiated hyphae of the substrate, sessile or on short protrusions, solitary, lateral, brown, smooth, and thick-walled, mostly obovoid 5–10 × 2–2.5 µm (x̄ =9 × 2.4 µm, n=20). Sexual state not observed after incubation for 2 months at 25 °C.
Material examined – India, Tamil Nadu, Tiruvarur, Muthupet mangroves (10.4° N 79.5° E), on decaying woody stem of the halophyte Suaeda monoica Forssk. ex J.F.Gmel. (Amaranthaceae) 28 November 2015, B. Devadatha (AMH9946, holotype), ex-type living culture NFCCI-4273.
GenBank numbers – MF182397 (ITS), KY863508 (LSU), MH571780 (SSU), MF687078 (tub2), MF182399 (tef1)
Notes – Our present collection of Scedosporium marina (NFCCI-4273) has been assigned to Scedosporium based on its similar morphological characteristics in having Graphium-like synnemata and scattered, poorly differentiated, percurrent conidiogenous cells (Gueho 1991). The present taxon, Scedosporium marina (NFCCI-4273) and S. aurantiacum (FMR8630) share similar morphological characteristics in producing three different types of conidia like the obovoid, or sub cylindrical, cylindrical or claviform, sessile obovoid conidia with overlapping conidial dimensions and yellow diffusible pigments on PDA. However, combined multigene phylogenetic anlayses of combined datasets of ITS and tub2 revealed that Scedosporium marina (NFCCI-4273) formed distinct lineage sharing a sister relation with Scedosporium aurantiacum with significant statistical support 100% ML, 97% MP (105). Morphologically S. marina (NFCCI4273) is distinct from S. aurantiacum (FMR8630) in having long and wide synemmata (170–1110 × 10–25 vs 330–750 × 7.5–17.5), smaller heads (60–140 × 60–165
vs 60–70 × 140). The condiogenous cells of S. marina (NFCCI-4273) are percurrent and long in contrast to S. aurantiacum (FMR8630) (25–55 × 2–2.5 vs 10–37 × 1.5 2.5).
Figure 1 – Scedosporium marina on a twig (AMH-9946, holotype). a. Colonies on decaying woody stem of Suaeda monoica. b−c Synnemata. d−e, h Head and conidiophores. f Apical part of synnema producing conidia. g Conidiogenous cells with annellidic conidia. i Subcylindrical conidia. k−l Claviform conidia. m−o Obovoid conidia. Scale bars: b=50 µm, c=100 µm d−o=10 µm
Figure 2 – Scedosporium marina in culture (NFCCI-4273). a Synnemata on PDA b−c Synnemata. g−h Culture on PDA after 14 days. d−e Slimy head and Conidiophores. f Conidiogenous cells with annellidic conidia. l Apical part of synnema producing conidia. m Subcylindrical conidia. n−r, s Sessile obovoid conidia o−q Claviform Conidia. Scale bars: b−c=100 µm d=50 µm, e−f, i−s=10 µm