Podosphaera sect. Sphaerotheca, subsect. Sphaerotheca (Braun & Cook, 2012

Yadav, Sanjay, Verma, Sanjeet Kumar & Singh, Raghvendra, 2021, A new species of Podosphaera sect. Sphaerotheca subsect. Sphaerotheca from India-first report of powdery mildew causing wilting and ultimately death of leaves of Filipendula vestita, Phytotaxa 491 (2), pp. 131-142 : 139-140

Key to species of Podosphaera sect. Sphaerotheca reported on Rosaceae

1. Appendages septate ............................................................................................................................................................................2

- Appendages aseptate ..........................................................................................................................................................................3

2. Appendages longer than chasmothecial diam ....................................................................................................................................4

- Appendages shorter than chasmothecial diam ...................................................................................................................................5

3. Chasmothecia 76–99(–124) μm diam.; peridium cells 4–14.5 μm diam.; appendages 1.6–4.8 μm wide................ P. filipendulensis

- Chasmothecia 75–90 μm diam.; peridium cells 8–20 μm diam.; appendages 5–10 μm wide ........................................... P. spiraeae

4. Width of appendages up to 12 μm................................................................................................................................. P. filipendulae

- Width of appendages less than 12 μm ................................................................................................................................................6

5. Peridium cells up to 15 μm diam.......................................................................................................................................... P. niesslii - Peridium cells more than 15 μm diam................................................................................................................................................7

6. Appendages more than 6 times as long as the chasmothecial diam ...................................................................................................8

- Appendages less than 6 times as long as the chasmothecial diam .....................................................................................................9

7. Chasmothecia (55–)60–85(–90) μm; appendages 3–8 μm wide; ascus 60–80 × 50–70 μm; ascospores (16–)20–25(–28) × 9.5–18 μm................................................................................................................................................................................... P. physocarpi

- Chasmothecia 65–95 μm; appendages 3–7 μm wide; ascus 60–90 × 50–70 μm; ascospores 16–21 × 13–18 μm ............ P. volkartii

8. Chasmothecia 90–130 μm diam.; appendages 1–10 times as long as the chasmothecial diam .............. P. ferruginea var. albiflorae

- Chasmothecia 75–100(–105) μm diam.; appendages 1–6 times as long as the chasmothecial diam..... P. ferruginea var. ferruginea

9. Peridium cells up to 15 μm diam.; appendages up to 5 μm wide............................................................................. P. stephanandrae

- Peridium cells more than 15 μm diam.; appendages more than 5 μm wide.....................................................................................10

10. Appendages simple............................................................................................................................................................. P. pannosa

- Appendages simple to branched.......................................................................................................................................................11

11. Appendages 0.25–6 times as long as the chasmothecial diam., 3.5–8 μm wide, ± brown when mature........ P. aphanis var. aphanis

- Appendages 0.25–2.5 times as long as the chasmothecial diam., 3.5–6 μm wide, hyaline or yellowish ....... P. aphanis var. hyalina