Platygramme, Fee, 1874

Kalb, Jutarat & Kalb, Klaus, 2017, New lichen species from Thailand, new combinations and new additions to the Thai lichen biota, Phytotaxa 332 (2), pp. 141-156 : 150-151

Key to the Thai species of Platygramme

1. Ascospores transversely septate, stictic acid present, sections K+ persistent yellow solution........................................................2.

- Ascospores submuriform or muriform, secondary products lacking or echinocarpic acid present..................................................3.

2. Ascospores 12–20 × 5–6 μm, 3–5-septate, labia first entire, becoming striate with age, exciple basally blackish brown.................. ........................................................................................................................................................... P. microspora Sutjaritt. & Kalb

- Ascospores 15–23 × 5–7 μm, 4–6-septate, labia entire, not becoming striate with age, exciple basally hyaline to light brown ........ ................................................................................................................................................................. P. discurrens (Nyl.) Staiger

3. Ascospores large, exceeding 115 μm in length.................................................................................................................................4.

- Ascospores small- to medium-sized, not exceeding 115 μm in length.............................................................................................5.

4. Secondary products lacking, ascospores 125–180 × 30–40 μm.............................. P. platyloma (Müll. Arg.) M. Nakan. & Kashiw.

- Echinocarpic acid present, ascospores 160–200 × 30–40 μm.............................. P. pudica (Mont. & Bosch) M. Nakan. & Kashiw.

5. Asci with 1 ascospore, very rarely (especially in young stages) with 2 ascospores, 70–115 × 20–30 μm,14–24 × 1–9-septate, disc concealed or slightly opened, black or darkbrown without or with a thin white pruina ...... P. commutabilis (Kremp.) A. W. Archer

- Asci with more than 1 ascospore.......................................................................................................................................................6.

6. Asci 2(–4)-spored, ascospores 65–100 ×14–20 μm, 19–24 × 1–5-septate, disc widely open, non-pruinose ...................................... ........................................................................................................................................................... P. subcolubrosa J. Kalb & Kalb

- Asci 4–8-spored, disc open or concealed...........................................................................................................................................7

7. Disc concealed, asci 4–8-spored, ascospores 25–45 × 10–15 μm, 5–7 × 1–3-septate.............. P. subarechavaletae Poengs. & Kalb

- Disc widely open, usually with a thick white pruina, asci 6–8-spored..............................................................................................8

8. Ascospores 50–90 (–105) × 15–22 μm, 12–19 × 1–4-septate, lips entire, carbonization restricted to the wedge-shaped apices of the lips, without crystals in carbonized parts ................................................................................................ P. caesiopruinosa (Fée) Fée

- Ascospores 40–75 × 14–18 μm, 8–14 × 1–2-septate, lips becoming striate with age, carbonzation reaching the base of the lateral exciple (at least in older ascomata) with clumps of large crystals in carbonized parts..... P. australiensis Staiger & Matthes-Leicht