Cadophora obscura Nannf., Svenska Skogsvardsfoereningens Tidskrift 50: 418 (1934)

Bien, Steffen & Damm, Ulrike, 2020, Arboricolonus simplex gen. et sp. nov. and novelties in Cadophora, Minutiella and Proliferodiscus from Prunus wood in Germany, MycoKeys 63, pp. 119-161 : 119

Cadophora obscura Nannf., Svenska Skogsvardsfoereningens Tidskrift 50: 418 (1934) Figures 5F , 11

≡ Phialophora obscura (Nannf.) Conant, Mycologia 29(5): 598 (1937)

Type.

Sweden, Umeå, Sofiehem, Sofiehems trämassefabrik, from fresh water, E Melin leg., collection date unknown, UPS F-153532 - holotype (not seen); unknown source, E Melin, collection date unknown (isolated by E Melin and JA Nannfeldt No. 389:11, deposited in CBS collection by E Melin probably 1933), CBS H-7589, CBS H-7590, GLM-F117483 - isotypes; CBS 269.33 = GLMC 1896 - culture ex-isotype.

Description.

Sexual morph not observed. Asexual morph on SNA. Vegetative mycelium hyaline, smooth-walled, septate, branched, 1-3.5 µm wide, sometimes becoming brown with age, chlamydospores absent. Sporulation abundant, conidia formed on hyphal cells. Conidiophores reduced to conidiogenous cells. Conidiogenous cells enteroblastic, hyaline, smooth-walled, discrete conidiogenous cells cylindrical to navicular, often bent, sometimes constricted at the base, 3-19 × 2-3 µm, necks cylindrical, 1-3.5 × 1.5-2 µm, collarettes distinct, cylindrical to funnel-shaped, 0.5-1.5 µm long, 1-1.5 µm wide at the upper edge, opening 1-1.5 µm wide, periclinal thickening observed. Conidia aggregated in heads, hyaline, smooth-walled, aseptate, ellipsoidal to cylindrical, mostly slightly curved, with both ends rounded, (3-)3.5-6(-7) × 1.5-2(-2.5) µm, mean ± SD = 4.8 ± 1.2 × 1.7 ± 0.3 µm, L/W ratio = 2.8.

Culture characteristics.

Colonies on SNA flat with an entire to fimbriate margin, white to cinnamon, filter paper buff to olivaceous, lacking aerial mycelium, reverse same colours, 14-16 mm diam. in 2 wk (25 °C in the dark); Colonies on OA flat with an entire margin, olivaceous black to greenish-black, with honey to white margin, sometimes covered by floccose, olivaceous grey aerial mycelium, reverse same colours, 14-20 mm diam. in 2 wk (25 °C in the dark).

Notes.

Cadophora obscura was originally described by Melin and Nannfeldt (1934) from freshwater in Sweden. According to the CBS website, strain CBS 269.33 is an “ex-isotype” culture. However, as Melin and Nannfeldt (1934) only isolated this species once and stated that they handed the strains from their study over to the Centraalbureau voor Schimmelcultures in Baarn now Westerdijk Fungal Biodiversity Institute, this can only be the ex-holotype strain. However, we were not able to allocate this strain to the holotype without doubt.

This species had previously been regarded as belonging to the genus Phialophora ( Medlar 1915) and as a synonym of Phialophora bubakii ( Schol-Schwarz 1970). However, based on the phylogeny of this study, both species are distinct species of the genus Cadophora . Cadophora obscura (CBS 269.33) differs from C. bubakii (CBS 198.30) by forming conidiogenous cells that are mostly narrow cylindrical, while those of CBS 198.30 are often flask-shaped. Conidia of C. obscura are distinctly longer than those of C. bubakii ; subglobose-shaped conidia were not observed. Colony growth is slower compared to C. bubakii .

The ITS and EF-1α sequences of the ex-type strains of C. bubakii and C. obscura differ in 19 and 31 nucleotides, respectively. The TUB sequences of the two species were excluded from the analyses (see Notes of C. bubakii ).

The ITS sequence of CBS 269.33 is 100% identical with three strains isolated from archaeological wood in Greenland (586-C, 592-B, 588-A, NB Pedersen et al., unpubl. data).

Figures

Figure 5. Colony surface of analysed strains on OA medium. A Arboricolonus simplex GLMC 459 T B Cadophora africana CBS 120890 T C C. bubakii CBS 198.30 T D C. luteo-olivacea GLMC 1264 E C. novi-eboraci GLMC 1472 F C. obscura CBS 269.33 G C. prunicola CBS 120891 T H C. prunicola GLMC 1633 I C. ramosa GLMC 377 T J Minutiella pruni-avium GLMC 1624 T K Proliferodiscus ingens GLMC 1751 T L Proliferodiscus sp. GLMC 460. Cultures A, J-L after 4 wk. Cultures B-I after 2 wk. Strains with a superscript T are ex-type cultures.

Figure 11. Cadophora obscura A-J conidiophores and conidiogenous cells (arrows indicate short necks) K conidia A-K from SNA A-K LM. Scale bar: 5 μm (A applies to B-K).