A new approach to species delimitation in Septoria - CBS - KNAW

Verkley et al.Conidiomata simple or complex, with several merging cavities,lacking a differentiated ostiolum, opening by tearing of the wall;conidiomatal wall composed of a single layer of isodiametric cells,6–13 μm diam. Conidiogenous cells discrete, or integrated inshort, 1–2-septate conidiophores, hyaline, cylindrical, holoblastic,sympodial; conidia cylindrical, hyaline, smooth-walled, mostlycurved, rounded at the tip, attenuated to a truncate base,(0–)1–3-septate , not or only slightly constricted around the septa,with minute oil-droplets near the ends and the septa, 9–31 × 1.8–2.2 μm (MEA), 17–30 × 1.7–2.0(–2.5) µm (OA); Spermatia hyaline,ellipsoid, with rounded ends and minutely granular contents, 3–5 ×0.8–1.2 μm.Hosts: Coprosma robusta, Coprosma sp.Material examined: New Zealand, North Island, Bay of Islands area, N. of Russell,mycosphaerella-like sexual morph on living leaves of Coprosma robusta, G. Verkley2020, CBS H-21246, living single ascospore isolate CBS 113391.Notes: CBS 113391 was obtained from rehydrated spotted leavesof Coprosma robusta collected in New Zealand that contained amycosphaerella-like sexual morph. No mature asci were observedin this material, nor a septoria-like morph, but the isolate obtaineddeveloped pycnidia agreeing with conidia described for S.coprosmae (30 × 2 µm). In the multilocus phylogeny CBS 113391groups with CPC 19304, originating from Vigna unguiculata subsp.sesquipedalis in Australia, and CPC 19793, isolated from Syzygiumcordatum in Australia, and is also relatively closely related to S.verbenae (CBS 113438, 113481) isolated from Verbena officinalisin New Zealand. Aptroot (2006) investigated an isotype ofMycosphaerella coacervata from BPI and could only find “variouscoelomycetes”. It is unclear whether it contained a Septoria. Sydow(1924) provided a description of the sexual morph of M. coacervataand an associated spermatial state, but not of a Septoria.Septoria cruciatae Roberge ex Desm., Annls Sci. Nat., sér.3, Bot. 8: 20. 1847. Fig. 15.= Septoria urens Pass., Atti Soc. crittog. ital. 2: 31. 1879.= Septoria aparines Ellis & Kellerm., J. Mycol. 5: 143. 1889.≡ Rhabdospora aparines (Ellis & Kellerm.) Kuntze, Revisio generumplantarum 3 (2): 509. 1898.= Septoria asperulae Bäumler, Verh. zool.-bot. Ges. Wien 40: 142. 1890.= Septoria galii-borealis Henn., Bot. Jahrb. Syst. 37: 163. 1905 [non Bubák& Kabát].= Septoria galii-borealis Bubák & Kabát, Hedwigia 52: 350. 1912 [non Henn.,later homonym].?= Phleospora bresadolae Allesch., Ber. bot. Ver. Landshut 12: 60. 1892.?= Septoria relicta Bubák, Annls mycol. 4: 116. 1906.For more synonyms see Jørstad (1965).Description in planta. Symptoms leaf lesions indefinite, usually asingle one on each leaf expanding to ultimately cover the entirelamina, brown. Conidiomata pycnidial, epiphyllous, numerous,semi-immersed to immersed, subglobose to globose, dark brownto black, 170–240 µm diam; ostiolum central, circular, initially25–55 µm wide, later becoming more irregular and up to 90 µmwide, surrounding cells concolourous; conidiomatal wall 20–35 µmthick, composed of an inner layer of isodiametric to irregular cellsmostly 2.5–4.5 µm diam with hyaline cell walls up to 2 μm thick,and an outer layer of hyphal cells, 8–15 × 5–6.5 μm with orangebrown walls thickened up to 2 μm, well developed and up to 15μm thick in the upper part of the pycnidium wall. Conidiogenouscells hyaline, discrete, rarely integrated in 1-septate conidiophores,cylindrical, or narrowly to broadly ampulliform, holoblastic,proliferating rarely percurrently showing 1–2 indistinct annellations,sometimes (also) proliferating sympodially, 10–15(–22) × 3–5.5(–6) µm. Conidia filiform, curved to flexuous, rounded to somewhatpointed at the apex, attenuated modestly towards the truncatebase, (0–)2–3-septate, not constricted around the septa, hyaline,containing several large oil-droplets and granular material in theliving state and rehydrated state, (30–)42–54(–60) × 2.5–3.2 µm(living; rehydrated, 2.0–2.5 µm wide), released in white cirrhi.Description in vitro (20 ºC, diffuse daylight). Colonies on OA 8–12mm diam in 2 wk, with a glabrous, colourless, even margin; colonyrestricted, the surface mostly covered by pure white, woolly-floccoseaerial mycelium, immersed mycelium mostly bright or darkerherbage-green, brick in the centre, reverse dark green to black; ared pigment diffuses into the medium. Conidiomata developing inthe centre on the surface of the colony or in the aerial mycelium,releasing pale milky white to rosy-buff conidial slime. Colonies onMEA 5–7 mm diam in 2 wk, with a barely visible, irregularly ruffledmargin; colony restricted, hemispherical to irregularly pustulate,the surface entirely covered by a dense felty to woolly mat ofpale olivaceous-grey, locally reddish, aerial mycelium, immersedmycelium almost black; reverse olivaceous-black to black;conidiomata developing on the surface in the centre of colonies,releasing milky white to rosy-buff conidial slime. Conidiomata onOA olivaceous-brown to olivaceous, globose, single or aggregated,200–380 μm diam, on the agar mostly without a well-developedostiolum, the wall composed of a rather undifferentiated outer layerof loosely interwoven, pale brown hyphae with barely thickenedwalls, and an inner layer of globose to angular cells with hyalinewalls up to 2 μm thick. Conidia as in planta, mostly 3-septate, 35–65 × 2–2.5(–3) µm (OA).Hosts: Galium spp.Material examined: Czech Republic, Moravia, Milovice, forest Milovika stran, 15Sep. 2008, on living or decaying leaves of Galium odoratum, G. Verkley 6007,epitype designated here CBS H-21250 “MBT175354”, living cultures ex-epitypeCBS 123747, 123748. France, Libisey near Caen, on living leaves of G. cruciatum,Jul.-Sep. 1844, M. Roberge, “Col. Desmazieres 1863, no. 8, 200”, isotype PC0084552, with handwritten description in French; Libisey near Caen, on living leavesof G. cruciatum, July 1844, M. Roberge, PC 0084551; Puy-de-Dôme, Ambert, on G.cruciatum, 23 Aug. 1903, L. Brevière, PC 0084553. Germany, Thüringen, Berka a.Ilm, on leaves of G. rotundifolium, 21 July 1912, H. Diedicke, distributed in Sydow,Mycotheca germanica 1132, PC 0084548. Iran, Pass Ghaleh, on G. coronatum, 10July 1968, Sharif, PC 0084549. Romania, Bucharest, on G. mollugo, 4 Oct. 1974,G. Negrean, distributed in Herb. Mycol. Romanicum 50, 2476, PC 0084550.Notes: The description given above is based on the collections onGalium odoratum and G. cruciatum, including the well-preservedtype specimen from PC and the collection V6007, which agreeswell with this type material. Although the latter is from CzechRepublic and another host species than the type, it is selected hereas epitype as two cultures derived from it are also preserved inCBS. According to Jørstad (1965), on G. boreale conidia are 23–73× (1–)1.5–2(–2.5) µm (with mostly 3 septa), and on G. aparine37–88 × 1–1.5 µm (with up to 5 septa). Jørstad placed five namesin the synonymy of S. cruciatae, including S. asperulae from G.odoratum. He reported limited differences between material ondifferent species of Galium, and it is not unlikely that there is just onespecies capable of infecting several species of Galium. In additionto the names he listed as synonyms of S. cruciatae, S. relicta andPhleospora bresadolae, both described from G. odoratum (syn.Asperula odorata) in Czech Republic and Germany, respectively,252