Milesina woodwardiana Buchheit & M. Scholler

Bubner, Ben, Buchheit, Ramona, Friedrich, Frank, Kummer, Volker & Scholler, Markus, 2019, Species identification of European forest pathogens of the genus Milesina (Pucciniales) using urediniospore morphology and molecular barcoding including M. woodwardiana sp. nov., MycoKeys 48, pp. 1-40 : 1

Milesina woodwardiana Buchheit & M. Scholler sp. nov. Figure 7 a–f

Holotype.

Woodwardia radicans (L.) Sm., Spain, Islas Canarias, La Palma, Cubo de la Galga, ca. 2.5 km SW parking place at coastal highway W San Bartolomé, wayside in Laurosilva, 11 Aug 2017, V. Kummer (KR-M-0049033).

Further specimens examined (paratypes)Spain, Islas Canarias: La Palma, Cubo de la Galga, ca. 1.2 km SW of parking lot at coastal highway W San Bartolomé, wayside in Laurosilva, 16 Aug 2015, V. Kummer, II (KR, KR-M-0048787); La Palma, Cubo de la Galga, ca. 1.2 km SW parking lot at coastal highway W San Bartolomé, near waypoint 6, wayside in Laurosilva, 11 Aug 2017, V. Kummer, II (KR, KR-M-0049036); La Palma, Cubo de la Galga, ca. 1.25 km SW parking lot at coastal highway W San Bartolomé, between waypoint 6 and 7, wayside in Laurosilva, 11 Aug 2017, V. Kummer, II (KR, KR-M-0049034).

Description.

Spermogonia (0), aecia (I), telia (III) and basidia (IV) unknown. Uredinia hypophyllous, subepidermal, statistically distributed; sori round, wart-like elevations, 0.1-0.3 mm in diam., covered by brownish or yellow-brownish epidermis, on dark necrotic plant tissue margined by nerves, never on nerves directly, sori opening pore-like; peridium hemispheric, peridial cells colourless, about 7.5-25.0 × 7.5-10 µm, upper peridial cells more or less isodiametrical and lateral peridial cells elongated; urediniospores hyaline, ellipsoidal to obovoidal, sometimes subglobose to irregular, 25.5-46.5 × 15.0-25.0 µm, mostly 30.0-37.5 × 17.5-22.5 µm; cell wall thin, 0.5-1.2 µm, mostly 0.5-1.0 µm thick, densely echinulate without spine-free areas, densest at spore base, spines 2.0-3.2 µm long, mostly 3.0 µm long, slightly irregularly distributed, spines orientated in different directions, dense basal spines typically directed toward spore pedicel, distance between spines bases 0.5-5.0 µm, mostly 2.0-4.0 µm, spine base 0.6-1.3 µm, mostly around 1 µm; spore pedicel often laterally or semilaterally inserted, short and wide, 5.5-14 × 12.5-15.5 µm; germ pores scattered, 8-19 (21), mostly 10-14, 1.3-3.0 µm, mostly 2.0-3.0 µm diam., Ø 2.4 µm diam.; germ tubes septate, may develop simultaneously in one spore.

Distribution.

The species is only known north-eastern La Palma, Islas Canarias, Spain.

Etymology.

Referring to the English botanist Thomas Jenkinson Woodward (1745 - 1820) and the host plant Woodwardia radicans named after him.

Comment.

This species differs from M. blechni by the telial host plant genus ( Woodwardia ), by a higher number of germ pores/spore, longer spines and irregular spine orientation. Milesina woodwardiana is the first Milesina species known on Woodwardia ( Berndt 2008; Faull 1932). The absence of potential aecial hosts ( Abies spp.) in La Palma and all other Canary Islands ( Hohenester and Welss 1993, Ginovés et al. 2009) and the non-formation of telia indicate that the species is not host-alternating in La Palma. The Woodwardia radicans area ( Hohenester and Welss 1993), however, overlaps with those of Abies x borisii-regis, A. cephalonica and A. pinsapo in south-western Europe ( Liu 1971). If the rust is present in this area, it may be possible to observe the spore stages 0 and I on Abies spp. Woodwardia radicans is the only species of Woodwardia in Europe. There are numerous other species in SE Asia and N America ( Li et al. 2016). These areas may also coincide with the distribution area of M. woodwardiana .