Stilbella

Abstract

Two lichenicolous synnematous species of Stilbella are currently recognized: S. eichlerae, found once on the thallus of Cetraria islandica in Germany, and the newly described S. helmingeri, collected from Cladonia pocillum in Luxembourg.

Full text

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Diederich, Ertz & Braun – Flora of Lichenicolous Fungi – Vol. 2. Hyphomycetes – 2024
Stilbella Lindau
in Engler & Prantl, Nat. Panzenfam., Teil I, 1: 489 (1900). Type:
S. erythrocephala (Ditmar) Lindau
Molecular data: yes. Number of species: 2–0–0 (18).
Conidiomata synnematous, determinate, pale brown or
yellowish to blackish, not gelatinous. Stipe hyphae paral-
lel to slightly interwoven. Conidiophores verticillate. Co-
nidiogenous cells cylindrical to subulate phialides lacking
a ared collarette, in some species intermixed with sterile
hyphae. Conidia aseptate, subspherical, ellipsoidal, fusi-
form or clavate, subhyaline to pale coloured.
Ecology. On dung, soil, bark or wood, two species lichenicolous.
Stilbella eichlerae Brackel
Ber. Bayer. Bot. Ges. 89: 120 (2019). Type: Germany, Bayern,
Mittel franken, Nürnberger Land, Leinburger Forst, Leinburg,
49°26’05”N, 11°17’49”E, 370 m, on Cetraria islandica, 17 Sept.
2016, W. von Brackel 7729 (M – holotype; herb. Brackel – isotype).
Conidiomata synnematous, slender, determinate, smooth,
pale brown, 100–300 μm tall, stipe 45–65 μm diam., capitu-
lum 125–175 μm diam. Stipe hyphae medium brown, greyish
above, K–, parallel to interwoven, 2.5–3.5 μm diam., smooth
Stilbella
by P. Diederich & W. von Brackel
Diederich, P. & W. von Brackel. 2024. Stilbella. Flora of Lichenicolous Fungi 2: 400–402.
Abstract. Two lichenicolous synnematous species of Stilbella are currently recognized: S. eichlerae, found once on the thallus of Cetraria is-
landica in Germany, and the newly described S. helmingeri, collected from Cladonia pocillum in Luxembourg.
Stilbella eichlerae, Germany, holotype. Synnemata on the thallus of
Cetraria islandica. Photo: W. von Brackel. Scale bar: 200 μm.
Stilbella eichlerae, Germany, holotype. Conidiophores, conidia and ster-
ile hyphae (arrows). Photo: W. von Brackel. Scale bar: 5 μm.
Stilbella eichlerae, Germany, holotype. Conidiophores, conidia and
sterile, verruculose hyphae. Del. W. von Brackel. Scale bar: 5 μm.
1 Conidia subspherical, 2.3–3 × 2–2.5 μm; synnemata pale brown, 100–300 μm tall, stipe 45–65 μm diam., capitulum
125–175 μm diam.; conidiophores intermixed with sterile, verruculose hyphae; on Cetraria ....... Stilbella eichlerae (400)
1’ Conidia narrowly ellipsoidal, 4.7–6 × 1.7–2 μm; synnemata yellowish, 50–90 μm tall, stipe 10–20 μm diam., capitulum
15–35 μm diam.; sterile hyphae missing; on Cladonia ............................................................... Stilbella helmingeri (401)

401
Stilbella
to verruculose. Conidiophores verticillate. Conidiogenous
cells cylindrical to ask-shaped phialides, 7.5–15 × 2–4 μm,
intermixed with sterile, verruculose, apically rounded hyphae
up to 20 μm long, 1–4 μm wide. Conidia aseptate, subspheri-
cal to broadly ellipsoidal, subhyaline to pale brownish, with
a minute thickening at both ends, (2–)2.3–3 × 2–2.5(–3) μm.
Notes. A specimen on Cladonia foliacea had been attributed
to the same species by Brackel (2019), but is regarded here as
a distinct species with much smaller conidiomata (see below).
Ecology and host. On the thallus of Cetraria islandica.
Distribution. Europe (Germany), known only from the
type locality.
Reference. Brackel 2019.
Stilbella helmingeri Diederich, sp. nov.
Diagnosis: Distinguished from Stilbella eichlerae by the yellowish
synnemata, 50–90 μm tall, stipe 10–20 μm diam., capitulum
15–35 μm diam., and the narrowly ellipsoid, aseptate conidia
with pointed ends, 4.7–6 × 1.7–2 μm.
Etymology: Named after Thierry Helminger, curator of the herbar-
ium of the National Museum of Natural History, Luxembourg.
Type: Luxembourg, W Steinfort, quarry W of nature reserve, on Clad-
onia pocillum, 27 Aug. 2009, P. Diederich 16834 (BR – holotype).
MycoBank: MB855987
Conidiomata synnematous, determinate, slender, smooth, yel-
lowish, lower part almost translucent and sometimes slightly
swollen, 50–90 μm tall, stipe 10–20 μm diam., capitulum 15–
35 μm diam. Stipe hyphae hyaline, simple, parallel, smooth,
1–1.5 μm diam. Conidiophores not distinctly observed, prob-
ably verticillate. Conidiogenous cells cylindrical, phialidic,
1–1.3 μm thick; sterile, intermixed hyphae missing. Conidia
aseptate, narrowly ellipsoidal, with pointed ends, basally
slightly truncate, hyaline, smooth-walled, 4.7–6 × 1.7–2 μm.
Notes. This species is distinguished by the small, yellow
synnemata and the narrowly ellipsoidal, aseptate conidia.
Ecology and host. On the thallus of Cladonia pocillum.
Distribution. Europe (Luxembourg), known only from the
type locality.
Stilbella helmingeri, Luxembourg, holotype. Synnemata on the thallus of Cladonia pocillum Scale bar: 50 μm.
Stilbella eichlerae Stilbella helmingeri

402
Diederich, Ertz & Braun – Flora of Lichenicolous Fungi – Vol. 2. Hyphomycetes – 2024
Poorly known species
Stilbella sp.
Conidiomata synnematous, determinate, brownish, 30–60
μm tall, stipe 25–45 μm diam., capitulum 40–80 μm tall,
35–90 μm diam. Conidio genous cells phialidic. Conidia
subspherical, hyaline, 1–1.5 μm diam.
Notes. Brackel (2019) reported a second German specimen
of Stilbella eichlerae on Cladonia foliacea. We have exam-
ined this material and found it to be a distinct species with
particularly small synnemata.
Ecology and host. On the thallus of Cladonia foliacea.
Distribution. Europe (Germany).
Specimen examined. Germany: Hessen, Frankfurt, Botanischer
Garten, Siesmayerstraße, Dachäche, on Cladonia foliacea,
2019, Eichler & Cezanne (herb. Cezanne-Eichler 11120).
Acknowledgements
M. Eichler and R. Cezanne (loan of specimen of Stilbella sp.).
Reference
Brackel, W. von. 2019. Weitere Funde von echtenbewohnenden
Pilzen in Bayern – Beitrag zu einer Checkliste VI. Ber. Bayer.
Bot. Ges. 89: 105–126.
Stilbella helmingeri, Luxembourg, holotype. A, Upper part of stipe, capitulum and conidia. B, The same, after pressure on cover glass. C, Co-
nidia. A–B, in water, C, in Phloxine. Scale bar: 10 μm.
An undescribed species of Stilbella on the thallus of Cladonia fo-
liacea (Cezanne-Eichler 11120), previously included in S. eichlerae,
may be confused with S. helmingeri. Scale bar: 100 μm.