Flora of New Zealand Series

Type : Arthopyrenia cerasi (Schrad.) A.Massal., typ. cons.  [=Verrucaria cerasi Schrad.]

Description : Flora (1985: 14).

Arthopyrenia is widespread genus of c. 100 described species (Kirk et al. 2001), most being corticolous. It is included in the family Arthopyreniaceae (Kirk et al. 2001; Eriksson et al. 2004; Pennycook & Galloway 2004). For many years Arthopyrenia was used as a collective name for a variety of taxa with blackened perithecial ascomata and colourless 1-multi-septate ascospores. Taxa formerly included in Arthopyrenia are now accommodated in the following genera: Anisomeridium, Acrocordia, Eopyrenula (Harris 1973; Aptroot 1991a), Naetrocymbe (Eriksson 1981; Harris 1995; Santesson et al. 2004), Strigula, Polymeridium (Harris 1986, 1993, 1995), Pyrencollema, Leptorhaphis (Aguirre-Hudson 1991); Stigmatella, Lithothelium (Aptroot 1991a). The Flora account (Galloway 1985a: 14–17) discussed eight taxa, four of which are now placed elsewhere, viz.: A. punctiformis to Naetrocymbe (Harris 1995; Santesson et al. 2004), A. sublitoralis to Collemopsidium (Grube & Ryan 2002; see also Harris 1975; Coppins 1988, 1992j), A. subbiformis in Anisomeridium (Harris 1995) and A. suffusa to Polymeridium (Harris 1986). Modern ideas on characters defining taxa in Arthopyrenia derive from the work of Harris (1975) on North American species. Harris accepts the genus as non-lichenised and to some extent parasitic with some species regularly associating with Trentepohlioid algae. Useful notes on corticolous taxa are included in Foucard (1992). Aptroot (2002c: 103) opines that "differences between species of Arthopyrenia are not very discrete and do not warrant a separation at the generic (let alone familial) level". His broader concept of the genus is "characterised by the branched, but not anastomosing pseudoparaphyses, which may disappear in later stages, and the usually somewhat sole-shaped ascospores, which always have a broader and shorter upper cell and a longer and more slender lower cell". Conservation of the name Arthopyrenia A.Massal. with a conserved type is discussed in Gams (1999: 8–7).

Species of Arthopyrenia are usually characteristic of pioneer bark communities (Harris 1975; Coppins 1988, 1992b; Grube & Hafellner 1990; Aguirre-Hudson 1991: 123–124; Foucard 1992; Kainz et al. 2001). Following Harris's work, species are presently recognised on the basis of their ascolocular ascomata, black or brownish black, round to slightly ellipsoidal and hemispherical or ±flattened, the wall consisting of fungal cells intermixed with host bark cells; not developing a pseudostroma; pseudoparaphyses branched and anastomosing; asci bitunicate, obpyriform to cylindrical with a narrow and pointed internal apical beak; 8 colourless to brown, narrowly ovate ascospores that are 1–3-septate, the spore wall sometimes ornamented and the gelatinous sheath usually well-developed (Aguirre-Hudson 1991; Foucard 1992). Ascospore septation, the presence of a perispore and the pseudoparaphyses are best seen in sections treated with 10% K (Foucard 1992). Currently, five species are recognised in New Zealand, four of these apparently endemic. The genus is still very much in need of collection and study here.

The type of Arthopyrenia (Acrocordia) macquariensis C.W. Dodge (Dodge 1971: 454) from Macquarie I., and reported to occur also on the Auckland Is, the Mutton Bird Is near Stewart Is, and on the summit ridge of Phipps Peak at Arthur's Pass (Dodge 1971: 455), was not examined and is not included here.