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

A new approach to species delimitation in Septoriavisible; colonies irregularly pustulate to hemispherical, immersedmycelium olivaceous-black to black, glabrous, the surface bearingnumerous droplets of milky white to dirty buff conidial slime emergingfrom scattered pycnidial conidiomata; reverse olivaceous-black toblack. Colonies on CHA 3–5 mm diam in 2 wk [7–10 (22–26) mm in6 wk], the margin distinctly ruffled, glabrous, ochreous to greyish;colonies irregularly pustulate, immersed mycelium olivaceousblack,lacking aerial mycelium; milky white to dirty buff conidialslime emerging from scattered pycnidial conidiomata; reverseblood colour.Conidiomata (OA) as in planta, single and pycnidial, brownto black, glabrous, 85–150 µm diam, with a single ostiolum up to50 µm wide, rarely also merged into multilocular stromata up to300 µm diam which may have several openings; conidiogenouscells as in planta, proliferating sympodially and/or percurrently,9–20 × 4–7 µm; conidia as in planta but longer, 30–65(–72) ×1.5–2(–2.2) µm.Hosts: Polygonum spp.Material examined: Austria, Tirol, Ötztal, Sautens, on living leaves of Polygonumpersicaria, 30 July 2000, G. Verkley 1024, CBS H-21213, living culture CBS 108982.Netherlands, prov. Utrecht, Baarn, Zandvoordtweg, same substr., 9 July 1967,H.A. van der Aa 98, CBS H-18695, living culture CBS 347.67; same substr., prov.Limburg, St. Jansberg, near Plasmolen, 9 Sep. 1999, G. Verkley 926, CBS H-21208,living cultures CBS 102330, 102331; same substr., prov. Limburg, Savelsbos, 28June 2000, G. Verkley 967, CBS H-21212, living cultures CBS 109007, 109008;Prov. Zeeland, Zuid-Beveland, community of Borsele, Valdijk near Nisse, 27 Aug.2001, G. Verkley 1110, CBS H-21164, living culture CBS 109834. New Zealand,North Island, Coromandel, Tairua Forest, along roadside of St. Hway 25, nearcrossing 25A, 23 Jan. 2003, G. Verkley 1843, CBS H-21242, living culture CBS113110.Notes: More than ten Septoria species have been described fromthe host genus Polygonum, of which S. polygonorum is the oldestone. The material available for the present study agrees generallywell in morphology with the description of S. polygonorum providedby other authors. Priest (2006) described the conidiogenous cellsas holoblastic (first conidium), producing subsequent conidiaenterobastically, seceding at the same level (mode “Event 13:enteroblastic non-progressive”). Muthumary (1999), who studiedtype material of S. polygonorum from PC, observed sympodiallyproliferated cells. Priest may have overlooked the sympodialconidiogenesis, as in the present study sympodially proliferatingcells were also observed in field specimens of S. polygonorum.The strains available from distant geographical origins showedhighly similar sequences for seven loci. The multilocus phylogenyindicates a rather isolated position of S. polygonorum (Fig. 2).Septoria protearum Viljoen & Crous, S. Afr. J. Bot. 64: 144.1998.Description in planta: Symptoms leaf spots varied according to thehost. Conidiomata pycnidial, epiphyllous or amphigenous, semiimmersedor becoming erumpent, subglobose to globose, darkbrown to black, 65–200 µm diam; ostiolum central, circular, slightlypapillate, 18–30(–60) µm wide, surrounding cells concolourous,releasing white cirrhi of conidial slime; conidiomatal wall 10–22 µmthick, composed of 3–4 layers of brown, isodiametric to irregularcells mostly 5–10 µm diam with dark brown cell walls up to 2 μmthick, sometimes with an an inner layer of hyphal to isodiametriccells 3.5–5 μm diam with thin, hyaline walls. Conidiogenous cellshyaline, discrete and globose or doliiform often with an elongatedneck, or integrated in 1–5-septate conidiophores up to 30 µmlong and narrowly to broadly ampulliform, holoblastic, proliferatingpercurrently with indistinct annellations as well as sympodially,4–12 × 1.5–3.5(–5) µm. Conidia hyaline, cylindrical, subcylindricalto obclavate, straight to curved, rounded to somewhat pointedat the apex, attenuated gradually or more abruptly towards thetruncate base, (0–)1–3(–4)-septate, not constricted around thesepta, containing minute oil-droplets and granular material inrehydrated state, (6–)12–22(–30) × 1.5–2 µm (rehydrated). Sexualmorph unknown.Description in vitro (18 ºC, near UV): Colonies on OA 11–16 mmdiam in 1 wk, 23–30 mm in 2 wk, with an even, slightly undulating,colourless margin; colonies plane, spreading, immersed myceliumochreous to pale luteous or rosy-buff and rarely also with greenishtinges, aerial mycelium absent or scarce with few grey to rosybufftufts; conidiomata developing mostly immersed in the agar,scattered or in concentric zones, olivaceous-black, releasingdroplets of milky white to pale salmon conidial slime. Reversecinnamon to hazel or fawn, or rosy-buff. Colonies on MEA 32–36mm diam in 2 wk, with an even, (vinaceous) buff to colourlessundulating margin; colonies restricted with a cerebriform elevatedcentral area or lower and more spreading, radially striate, the entiresurface covered by a dense mat of finely felted, somewhat woolly,white to greysh, or salmon to flesh aerial mycelium; reverse dark,fawn to brown-vinaceous, or olivaceous-black mixed with brightrust to coral. Conidiomata developing after 1 wk, mostly immersedand releasing whitish conidial slime. Colonies on CHA 17–19 mmdiam in 1 wk, 25–31 mm in 2 wk, with an even, saffron margin withsome diffuse white aerial mycelium; colonies spreading but slightlyelevated in the centre, entirely covered by a dense mat of purewhite, locally weakly salmon, woolly and somewhat sticky aerialmycelium, in the marginal area later with a glaucous haze; reversein the centre chestnut, surrounded by rust and apricot zones,margin saffron. Sporulation as on MEA.Conidiomata (OA) pycnidial, globose, single or merging intocomplexes up to 220 µm diam, brown to black, the wall composedof pale brown textura angularis with cells up to 10 µm diam, innercells smaller and hyaline. Conidiogenous cells hyaline, discreteor integrated in simple, 1(–2)-septate conidiophores, cylindricalor narrowly to broadly ampulliform, holoblastic, proliferatingsympodially, and/or percurrently with indistinct annellations, andthen often showing a narrow neck of variable length, 5–10(–13.5)× 2.5–3(–3.5) µm. Conidia filiform to cylindrical, straight, moreoften curved or flexuous, or bent irregularly, rounded to somewhatpointed at the apex, attenuated gradually or more abruptly towardsthe narrowly truncate base, (0–)1–3-septate, not constricted atthe septa, hyaline, contents as in planta, (8–)12–22(–25) × 1.5–2µm (CBS 119942), (12–)15–23.5(–31) × 1–1.5 µm (CBS 179.77),17–35 × 1–1.5(–2) µm (CBS 658.77).Hosts: Asplenium ruta-muraria, Boronia denticulata, Geum sp.,Ligustrum vulgare, Myosotis sp., Nephrolepis sp., Pistacia vera,Protea cynaroides, Protea sp., Skimmia sp. and Zanthedeschiaaethiopica.Material examined: Germany, Potsdam, Maulbeerallee beneath the Orangerie, onliving leaves of Asplenium ruta-muraria, 17 Nov. 2005, V. Kummer 0045/3, CBSH-19729, living culture CBS 119942. Italy, details of loc. unknown, on Pistacia vera,June 1951, deposited by G. Goidánich, living culture CBS 420.51; on Ligustrumvulgare, June 1959, M. Ribaldi, living culture CBS 390.59. Netherlands, Reeuwijk,in leaf spot of Skimmia sp., commercially cultivated under plastic ‘tunnels’, 1996, J.de Gruyter, CBS H-21190, PD 96/11330 = CBS 364.97. New Zealand, Auckland,on Myosotis sp., Dec. 1976, H.J. Boesewinkel, CBS H=18209, living culturewww.studiesinmycology.org281