Flora of New Zealand Series

Type : Santessoniella polychidioides (Zahlbr.) Henssen [=Lemmopsis polychidioides Zahlbr.]

Description : Thallus minute, greyish or brownish, granular to subfruticose, corticate on all surfaces, attached to substratum by a loosely interwoven mat or by agglutinated strands of pigmented rhizoidal hyphae, occasionally with a blackish prothallus. Lobes flattened or terete, frequently knotted. Photobiont Nostoc, ±uniformly distributed throughout thallus. Ascomata apothecia, biatorine. Exciple annular of radiating hyphae. Hamathecium of septate, occasionally branched paraphyses, 2 μm diam., widening to 4 μm at apices. Hymenium I+ reddish. Asci 8-spored, apex with a narrow, amyloid ring (tube). Ascospores colourless, simple, ellipsoidal, warted or smooth. Conidiomata pycnidia, globose, concolorous with or paler than ascomata, lateral, producing small, bacillar conidia, (4–5 × 1 μm) from short-celled conidiophores [type IV of Vobis (1980)]. Development of conidiophores and conidia corresponds to Umbilicaria -type (Vobis 1980). No lichen substances detected by TLC or HPLC.

Santessoniella, included in the family Pannariaceae (Eriksson et al. 2004; Pennycook & Galloway 2004; Eriksson 2005), appears most closely related to Parmeliella from which it differs in thallus structure. The genus was recently monographed by Henssen (1997) who recognised six species: one with three varieties from the boreal/arctic region, two from Japan and three from South America. Jørgensen (1998b, 1999a) described two additional species from New Zealand; Henssen (2000) a new species from Chile, plus a key to eight species and notes on the delimitation of the genus; Henssen & Kantvilas (2000) a new species from Tasmania; and Jørgensen (2000d) transferred a North American species to the genus, bringing the total of known species to 10. Recent molecular studies on the family Pannariaceae (Ekman & Jørgensen 2002) affirm the presence of Santessoniella within the family, but show its type, S. polychidioides, as nesting within Psoroma s. str., suggesting that Santessoniella is heterogeneous as earlier noted by Jørgensen (1998b, 2001b). Jørgensen (2003c, 2004a) has segregated one species formerly in Santessoniella into the newly described Austrella (q.v.), leaving eight species in Santessoniella, one of which is known from New Zealand.