Smaragdiniseta musae Samarakoon & Chomnunti, 2022

Samarakoon, Binu C., Wanasinghe, Dhanushka N., Bhat, Jayarama & Chomnunti, Putarak, 2022, Taxonomy and phylogeny of Smaragdiniseta musae sp. nov. and Albifimbria verrucaria (Hypocreales, Stachybotryaceae) on Musa from Thailand, Biodiversity Data Journal 10, pp. 89360-89360 : 89360

Smaragdiniseta musae Samarakoon & Chomnunti sp. nov.

Materials

Type status: Holotype. Occurrence: occurrenceRemarks: Found on a dead leaf of Musa sp.; recordNumber: BNS264; recordedBy: Binu C. Samarakoon; disposition: Living cultures: MFLUCC 22-0015 and MFLUCC 22-0016; associatedSequences: GenBank MFLUCC 22-0015: ON563485 (ITS), ON586151 (rpb2), ON572191 (tub2); MFLUCC 22-0016: ON563486 (ITS), ON58615(rpb2), ON572192 (tub2); Taxon: scientificName: Smaragdiniseta musae Samarakoon & Chomnunti; kingdom: Fungi ; phylum: Ascomycota ; class: Sordariomycetes ; order: Hypocreales ; family: Stachybotryaceae ; genus: Smaragdiniseta ; specificEpithet: musae; taxonRank: species; scientificNameAuthorship: Samarakoon & Chomnunti; Location : continent: Asia ; country: Thailand; stateProvince: Chiang Rai; locality: Mae Sai ; Identification : identifiedBy: Binu C. Samarakoon; Event : year: 2019; month: June ; day: 16; habitat: Terrestrial ; Record Level : institutionID: MFLU; collectionID: MFLU 22-0047

Description

Saprobic on dead leaves of Musa sp. Sexual morph: Undetermined. Asexual morph: Sporodochia 0.2-0.35 mm diam., cup-shaped, scattered, solitary, circular with an entire margin, initially emerald green, later becoming black, composed of hyaline, erect conidiophores, surrounded by filamentous white marginal hyphae and setae at periphery. Fungal hyphae arranged in parallel like a palisade layer, compacted, verrucose, olivaceous-brown or hyaline, sometimes warticulate, septate, branched, irregularly thick-walled, with ultimate hyphal cell rounded at apex and flat at base; hyphal cells: 10-14 × 0.8-2.5 μm (x̄ = 13.3 × 1.6 μm, n = 30). Aggregated hyphae hyaline or emerald green when immature, tan brown at maturity. Setae fast growing from marginal hyphae, numerous, aggregating as a pale grey brush, elongated, straight or slightly curved, tapering towards apex, hyaline, septate, unbranched, apiculate at apex, sometimes caudate, truncate or rounded, swollen to globose to ovate or rounded at base, setae wall 0.4-1.5 μm (x̄ = 0.8 μm, n = 30) thick, often smooth, sometimes rough with hyaline acellular coatings, (60-)90-160(-250) × 0.8-2.8 μm (x̄ = 126.4 × 1.6 μm, n = 30); septa 4-8 μm apart. Marginal hyphae often coiling or growing around the setae or projecting out, forming a wefty cover around setae, 95-125 μm (x̄ = 106 μm, n = 30) wide. Conidiophores 4-14 × 1.3-2.5 μm (x̄ = 12.9 × 1.7 μm, n = 30), macronematous, hyaline, smooth, thin-walled, arising from sub hyaline or pale brown, with slightly thickened and swollen basal cells, often with a narrow truncate base, wider in the middle, tapering to rounded at apex, 3-4 × 5-6 μm (x̄ = 3.5 × 5.5 μm, n = 10), septate, rarely unbranched, mostly branched and with 2-3 conidiogenous sub-branches at each node. Conidiogenous cells phialidic, rough or thin-walled, rod-shaped, elongated or ovate, 4-9 × 1-3 μm (x̄ = 6.8 × 1.9 μm, n = 20), without a collarette, pinching off simple conidia at the apex of each phialide. Conidia simple, hyaline, smooth, thin-walled, elliptic or slightly ovate, rounded at one end and acute at other end, with two distinct guttules at vertical ends, sometimes with 3-5 guttules, 6-10 × 2-3.5 μm (x̄ = 8.3 × 2.7 μm, n = 10).

Culture characteristics. Conidia germinating on PDA after 48 hours, germ tubes being produced from the acute end. Colonies growing on PDA reaching 20 mm diam. after 2 weeks in light conditions at 25°C, mycelium mostly immersed, not slimy, cottony, pinkish-white, dense in the middle and comparatively sparse at the periphery. Radially and unevenly striated, colonies have a slightly wrinkled appearance from the top. The formation of sporodochia was not observed in mature colonies.

Etymology

The species epithet reflects the host genus, Musa .

Notes

Based on BLASTn search results of ITS, tub2 and rpb2 sequence data, Smaragdiniseta musae (Fig. 1 ) showed a high percentage identity (ITS = 97.23%, tub2 = 89.16% and rpb2 = 91.10%) without gaps to S. bisetosa (CBS 459.82). In the multigene phylogeny, S. musae clustered with S. bisetosa in having strong statistical support (100% ML, 1.00 BYPP) (Fig. 3 ). The base pair comparison of ITS, tub2 and rpb2 of our new taxon revealed 3.14% (17/540), 12.36% (35/283) and 9.34% (63/674) nucleotide differences with S. bisetosa . Besides, S. musae differs from S. bisetosa by the conidial morphology. The conidia of S. musae have two distinct guttules at the vertical poles. In addition, some conidia bear minute guttules at the centre. However, the taxonomic illustration and description of S. bisetosa did not indicate the guttule formation in the conidia ( Rao and De Hoog 1983). Moreover, the conidia of S. bisetosa are obclavate, narrowly ellipsoidal or rod-shaped, whereas our new taxon has elliptic or slightly ovate-shaped conidia with a rounded top and an acute base. Both ends of the conidia of S. bisetosa are rounded or sometimes are found with a truncate base ( Rao and De Hoog 1983). We have not observed a truncate base in the conidia of S. musae . Furthermore, the marginal hyphae of S. musae often coil or grow around the setae, but have never overgrown. The marginal hyphae always reach around 95-125 μm of the setae and terminate at a point. According to the description of Rao and De Hoog (1983), in S. bisetosa , the marginal hyphae always covered the entire setae. Our new collection is similar in morphology to the other genera in Stachybotryaceae in having conidiophores where the ultimate branches become phialides ( Lombard et al. 2016). This feature phenotypically justifies the placement of our new collection in Stachybotryaceae. Based on distinct morphological characteristics and strong statistical support from our molecular phylogeny, Smaragdiniseta musae is, therefore, herein introduced as a new species on Musa sp. from Chiang Rai Province, Thailand. This is the first report of Smaragdiniseta on Musaceae from Southeast Asia. In addition, S. musae is the second taxon that is being described in this genus.

Figures

Figure 1. Smaragdiniseta musae (MFLU 22 - 0047, holotype) a, b sporodochia on the host; c, d cupulate sporodochia; e-i, q setae and marginal hyphae; j-l attachments of conidiophores and phialides; m-t conidia; u colony on PDA after 8 weeks. Scale bars: 400 μm (a, b), 100 μm (c, d, i, q), 50 μm (e-h), 20 μm (j), 10 μm (k-t).

Figure 3. Maximum Likelihood tree revealed by RAxML analyses of ITS, rpb 2 and tub 2 sequence data of selected genera of Stachybotryaceae, showing the phylogenetic position of Albifimbria verrucaria (MFLUCC 22 - 0017) and Smaragdiniseta musae (MFLUCC 22 - 0015, MFLUCC 22 - 0016). ML bootstrap supports (≥ 60 %) and Bayesian posterior probabilities (≥ 0.95 BYPP) are given above the nodes, respectively. The tree is rooted with Fusarium sambucinum (CBS 146.95) (Nectriaceae). Strains generated in this study are indicated in bold red. Ex-type strains are indicated in bold black. The scale bar represents the expected number of nucleotide substitutions per site.