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

A new approach to species delimitation in SeptoriaFig. 8. Septoria anthrisci. A. Conidia and conidiogenous cells in planta (CBS H-21185). B. Conidia on OA (CBS 109020). Scale bars = 10 µm.Material examined: Czech Republic, Moravia, Veltice, Forest of Rendez Vous,on living leaves of Aegopodium podagraria, 16 Sep. 2008, G. Verkley 6013, CBSH-21249, living cultures CBS 123740, 123741.Notes: Morphologically, the material from the Czech Republicavailable here agrees well with S. aegopodina as described byVanev et al. (1997) and Shin & Sameva (2004), although thepycnidia are larger than described by these authors (55–85 μmdiam). The species can easily be distinguished from S. aegopodiioccurring on the same host plant, as the conidia of that fungusare considerably larger (30–115 × 3.5–4 µm), and appearpredominantly 1-septate. The conidia more closely resemblethose of S. anthrisci. The diagnoses of S. aegopodina var. trailiibased on material on Pimpinella saxifraga, and of S. aegopodinavar. villosa on Pimpinella villosa, agree with the description of thetype variety. Both varieties are therefore considered synonyms ofS. aegopodina. In the multigene phylogeny S. aegopodina groupsfairly closely with S. oenanthicola, S. sii and S. oenanthis from thesame host family (Apiaceae), but other taxa from that family likeS. anthrisci are relative distant and belong elsewhere the Septoriaclade (Fig. 2). Other isolates grouping with S. aegopodii includethose of S. mazi from Mazus japonicus (Scrophulariaceae), S.campanulae from Campanula takesimana (Campanulaceae), andS. gentianae from Gentiana scabra var. buergeri (Gentianaceae).Septoria anthrisci Pass. & Brunaud, Rev. Mycol. (Toulouse)5: 250. 1883 [non P. Karst., Meddn Soc. Fauna Flora fenn.13: 10. 1884]. Fig. 8.Description in planta: Symptoms leaf spots numerous but small,circular to elliptical, visible on both sides of the leaf, the centre whiteto pale ochreous, surrounded by a relatively narrow, somewhatelevated, dark reddish brown to black margin. Conidiomatapycnidial, epiphyllous, sometimes also visible from the undersideof the lesion, mostly one, rarely up to three in each leaf spot,subglobose to lenticular, sometimes becoming cupulate, brownto black, immersed, 115–190 µm diam; ostiolum central, initiallycircular and 30–55 µm wide, later becoming more irregular andup to 100 µm wide, surrounding cells concolorous; conidiomatalwall about 12–20 µm thick, composed of an outer layer of palebrown angular cells 4.5–7 µm diam with somewhat thickenedwalls, and an inner layer of thin-walled, pale yellow angularto globose cells 2.5–5 µm diam. Conidiogenous cells hyaline,discrete, rarely integrated in 1-septate conidiophores, globoseor narrowly or broadly ampulliform, holoblastic, mostly with arelatively narrow elongated neck, proliferating percurrently severaltimes with distinct annellations, often also sympodially after or inbetween a few percurrent proliferations, 6–14(–18) × 2.5–5(–6)µm. Conidia filiform, straight, curved to flexuous, attenuatedgradually to a narrowly pointed apex and narrowly truncate base,(0–)1–3(–4)-septate (septa very thin and easily overlooked), notconstricted around the septa, hyaline, contents with several minuteoil-droplets and granular material in each cell in the living state, withminute oil-droplets and granular contents in the rehydrated state,(18–)25–59 (–65) × 1–2 µm (living; rehydrated, 1–1.8 µm wide).Sexual morph unknown.Description in vitro: Colonies on OA 4–6(–9) mm diam in 1 wk (18–22 mm in 22 d), with an even, glabrous, peach, later coral margin,with a concolorous pigment diffusing beyond the colony margin;colonies after 1 wk restricted, distinctly elevated in the centre,immersed mycelium first peach to pale coral, then deep coral, thecolony already appearing darker in the centre after 1 wk due tonumerous almost black pycnidial conidiomata in part merging intolarge complexes, releasing pale whitish or rosy-buff droplets ofconidial slime from one to several short-papillate or more elongatedneck-like openings; reverse in the centre blood colour, surroundedby a first intense peach, later scarlet or coral area. Colonies onCMA 7–8(–9) mm diam in 1 wk (18–21 mm in 22 d), as on OA.Colonies on MEA 6–11 mm diam in 1 wk (24–29 mm in 22 d), withwww.studiesinmycology.org241