Sporothrix fraxini R. Jankowiak, 2021

Ostafinska, Agnieszka, Jankowiak, Robert, Bilanski, Piotr, Solheim, Halvor & Wingfield, Michael J., 2021, Six new species of Sporothrix from hardwood trees in Poland, MycoKeys 82, pp. 1-32 : 1

Sporothrix fraxini R. Jankowiak sp. nov.

Fig. 7

Etymology.

From Latin, referring to the genus name of the host ( Fraxinus excelsior ).

Type.

Poland, Małopolskie Province, Zbylitowska Gora , from the gallery of Hylesinus varius on Fraxinus excelsior , May 2016, R. Jankowiak (O-F- 258630 holotype, culture ex-type CBS 147936) .

Description.

Sexual and asexual structures produced on sterilized ash twigs and on surface of malt agar in Petri dishes. Ascomata abundant, superficially or partly embedded in the agar, single or in groups; ascomatal base black, globose, (89-)110-161(-216) μm diam., with brown hyphal hairs, 14 to 65 μm long and 1.1 to 2.1 μm wide at the base; ascomatal necks black, straight or curved, (222-)332-461(-526) μm long, diameter (10.1-)11.3-16(-20.4) μm at the apex and (26.2-)29.1-41.4(-53) μm at the base. Ostiolar hyphae present, pale brown, septate, straight or rather tortuous, tapering towards the apex or sporadically dichotomous branching at the tip, (8-)10-20(-24) in number (21.4-)31.1-52.1(-73.6) μm long, (0.4-)0.7-1.1(-1.4) μm at the apex and (1.4-)1.8-2.4-(3.1) μm at the base. Asci evanescent. Ascospores one-celled, allantoid in side view (2.7-)2.9-3.5(-4.4) × (0.9-)1-1.4(-1.8) μm, elliptical in front view (2.2-)2.9-3.8(-4.7) × (0.8-)1.2-1.6(-1.8) μm, sometimes with residual sheath up to 1 μm thick, accumulated in white-color mass at the tip of the neck. Conidiophores hyaline, micronematous, simple or branched, straight, simple or branched, bearing several conidiogenous cells, either borne on vegetative hyphae or on upright hyphae. Conidiogenous cells blastic, cylindrical terminal or intercalary, straight or curved, tapering towards the apex, swollen apical part forming conidia by sympodial proliferation on hardly visible denticles, (13.6-)14.6-47.7(-99.6) μm long, (0.9-)1.2-1.6(-1.9) μm wide at the base. Apical part (0.8-)1.7-5.1(-10.6) μm long and (0.8-)1.1-2(-3) μm wide. Conidia hyaline, unicellular, smooth, obovoid to ellipsoidal, ends slightly rounded or truncate, (2.6-)3.4-5(-6.8) × (0.8-)1.1-1.6(-2) μm, formed directly on denticles. Culture characteristics: Cultures showing optimum growth at 25 °C (1 mm/d) followed by at 30 °C (0.9 mm/d), white, flat, growing in a circular pattern with smooth margins, with sparse aerial mycelium, often fading around the edges.

Host tree.

Fraxinus excelsior .

Insect vector.

Hylesinus crenatus , H. varius .

Distribution.

Poland

Additional specimen examined.

Poland, Małopolskie Province, Zbylitowska Góra, from the gallery of Hylesinus varius on Fraxinus excelsior , May 2016, R. Jankowiak (O-F-258631, cultures CBS 147938).

Notes.

This species is phylogenetically distinct from the other Sporothrix species based on the ITS, βT, CAL and TEF1-α sequences. Sporothrix fraxini is closely related to S. variecibatus . However, S. variecibatus does not produce a sexual morph, and has narrower conidia (2-3 μm) ( Roets et al. 2008) compared to S. fraxini (0.8-2 μm). In addition, the conidia of S. variecibatus are clavate while S. fraxini has obovoid to ellipsoidal conidia.

Sporothrix fraxini was represented by three isolates collected from the galleries of Hylesinus varius on Fraxinus excelsior . It corresponds to Sporothrix sp. 8 in the previous study of Jankowiak et al. (2019a).

Figures

Figure 7. Sporothrix fraxini sp. nov. (CBS 147936) a ascoma b ascomatal base c ostiolar hyphae d ascospores e conidiogenous cell with an inflated cluster of denticles at the apex f conidia g fourteen-day-old culture on MEA. Scale bars: 100 μm (a), 50 μm (b), 25 μm (c), 10 μm (d-f).