The genus Septoriella is characterised by mucoid appendage-bearing pale brown multiseptate conidia formed on holoblastic conidiogenous cells (Sutton 1980). The genus was reviewed later by Adrianova and Minter (2007) who recognised 11 species in the genus and provided a key to them. Only two of the species, S. halensis and S. phragmitis Oudemans have conidiomata (160–220 μm wide) and conidia (fusiform, 30–45 μm long and 5-7-septate) that are similar to those of the New Zealand fungus (Table 2).

A comparison of the three descriptions shows that the New Zealand fungus cannot be distinguished from S. halensis. Use of the key to accepted species of Septoriella (Adrianova & Minter 2007) also leads to S. halensis. This is the first record of a species of Septoriella in New Zealand. Most of the eleven taxa accepted in the genus are from temperate areas, the only exception being S. rockiana (Petrak) Nag Raj from Hawaii. Ten species occur on monocotyledon families and only one, S. viciae Adrianova & Minter, has been recorded on a plant (Vicia unijuga A.Braun) belonging to a dicotyledon family (Fabaceae). This record of S. halensis on P. insignis adds another dicotyledon family (Asteraceae) to the list. Most species of Septoriella have been recorded on dead or dying leaves or culms and are regarded as saprobes. The New Zealand collections of P. halensis were from leaf spots on living leaves of P. insignis but whether the fungus was acting as a pathogen or not is not known.