Tremella rhizocarpicola Diederich, Millanes & Wedin

Millanes, Ana M., Diederich, Paul, Westberg, Martin, Knutsson, Tommy & Wedin, Mats, 2014, Tremellarhizocarpicola sp. nov. and other interesting lichenicolous Tremellales and Filobasidiales in the Nordic countries, MycoKeys 8, pp. 31-41 : 32-34

Taxon classification Fungi Tremellales Tremellaceae

Tremella rhizocarpicola Diederich, Millanes & Wedin sp. nov.

Description.

Basidiomata inside the hymenium of the host, resulting in blackish swellings of the host apothecia; context hyphae difficult to observe, 2.5-3.5 mm thick, thin walled, with clamp connections; haustorial branches not observed. Hymenium hyaline, containing numerous probasidia, intermixed with the hymenium of the host; probasidial initials clavate, proliferations occurring through the basal clamp; hyphidia and cystidia absent. Basidia, when mature, narrowly ellipsoid to subcylindrical, with one transverse septum (never oblique or longitudinal), slightly constricted at the septum, the lower cell elongate, with an attenuated stalk-like base, (14 –)17– 44 × 7 –12(– 13) mm (incl. stalk); epibasidia 3-3.5 mm thick, up to 65 mm long. Basidiospores subglobose, with a large apiculus, 7.5-9.5 × 6-8.5 mm. Anamorph: conidial chains sometimes present in the hymenium. Individual conidia 3-5 × 3-5 mm.

Type.

NORWAY, Rogaland, Suldal, on the N side of lake Stranddalsvatnet. On N facing phylitic rock, 59°26.26'N, 6°43.48'E, ca. 1000 m, 18 Aug 1999, P.G. Ihlen 957 (BG: L-68612).

Distribution, ecology and host.

The new species is known from one locality in Denmark, two localities in Norway, and nine in Sweden, all growing inside the hymenium of Rhizocarpon lavatum on siliceous rocks, often along shorelines or near water.

Discussion.

The species was tentatively described by Diederich (1996: 170) as Tremella sp. 3. The single specimen known at that time was very small, but the discovery of 12 additional collections from Denmark, Sweden and Norway (Fig. 1A) is now enough for a formal description. There is little to add to the description and illustrations given by Diederich (1996), however. The only novelties are the wider range of basidium width and length (Fig. 1G) and the presence, occasionally, of an anamorph consisting of catenulate conidia. A sequence of the ITS barcode region is not provided, since recently collected specimens were too reduced for DNA extraction, and old specimens could not be amplified by PCR. Diederich (1996) indicated that this species was microscopically very similar to Tremella protoparmeliae , but Tremella rhizocarpicola could be distinguished by the formation of dark brown swellings on the host apothecia and by small differences in the size of the basidia. The additional specimens studied here show that there is an anamorph formed by catenulate conidia in Tremella rhizocarpicola , and the basidia of this species can be comparatively shorter and wider than those of Tremella protoparmeliae .

Additional specimens examined

(all on Rhizocarpon lavatum ): DENMARK. Faroe Islands: Nordoya, Bordö, Klaksvig, N end of Bordö Vig, rivulet Gravarå, 4 Sept 1956, G. Degelius (UPS: L-662460). - NORWAY. Oslo: Ekeberg, 13 May 1886, N.G. Moe (BG: L-58000). Rogaland: Suldal, on the north side of lake Stranddalsvatnet, 59°26.26'N, 6°43.48'E, ca. 1000 m, 18 Aug 1999, P.G. Ihlen 957 (BG: L-68612). - SWEDEN. Bohuslän: Foss, 1851, M.M. Floderus (UPS: L-662426). Bohuslän: Solberga, Rörtången, 10 June 1928, A.H. Magnusson 11329 (UPS: L-662425). Bohuslän: Ödsmål, Korsgården, 1 Aug 1931, A.H. Magnusson 12851b (UPS: L-662448). Bohuslän: Spekeröd, Groland, 28 Aug 1955, A.H. Magnusson 24616b (UPS: L-662457). Halland: Övraby, Sperlingsholm, 3 July 1851, T.M. Fries (UPS: L-132524). Halland: Tölö, Skårby, Valåsberget, 24 May 1925, A.H. Magnusson 9384b (UPS: L-662453). Halland, Karup par., SE of Båstad, on boulder in the river Kägleån, 10 Oct 1970, M. S. Christiansen 6498 (C). Härjedalen: Tännäs, Tännfallet waterfall in Tännån, 11 km NW of Tännäs, 62°29.04'N, 12°29.19'E, 6 July 2012, J. Hermansson 18827 (UPS: L-597926). Småland: Malmbäck, Älgaryd, 1875, P.G.E. Theorin (UPS: L-131500). Uppland: Danmark par., Linnés Hammarby, 2.4-2.5 km SE of Danmark church, the hill NE of the houses, 59°49.02'N, 17° 46.59 E, 25 m. 15 Sept 2007, G. Thor 22045 (UPS: L-167626).