(2415) Proposal to conserve the name Cercospora ( Ascomycota : Mycosphaerellaceae ) with a conserved type

Cercospora is one of the largest hyphomycete genera with more than 3000 names assigned to this genus and about 700 currently recognized species, causing hundreds of economically relevant diseases of cultivated plants worldwide. Additionally 281 species were referred to as C. apii s.l., which represents a complicated, hitherto only partly resolved complex of plurivorous and specialized species (Crous & Braun in CBS Biodiversity Series 1: 1. 2003; Braun & al. in IMA Fungus 4: 265. 2013). Clements & Shear (Gen. Fung.: 398. 1931) designated Cercospora apii as type of Cercospora and most authors followed this decision, e.g., Ellis (Dematiaceous Hyphomycetes: 275. 1971) and Pons & Sutton (in Mycol. Pap. 160: 6. 1988). This typification was based on the assumption that the generic name Cercospora was first published by Fresenius (Beitr. Mykol.: 91. 1863), issued on 18 August 1863, which is, however, incorrect as discussed in detail by Braun (Monogr. Cercosporella, Ramularia 1: 41. 1995). The name Cercospora was published earlier (in the first half of 1863) by Fuckel (Fungi Rhen. Exs., Fasc. II, no. 117. 1863 and in Hedwigia 2(15): 133. 1863). Fuckel (l.c.) ascribed the new generic name to Fresenius: “NB. Genus Cercospora Fres. Passalora valde affinis est, sed constanter sporidiis multiseptatis differt”. Cercospora penicillata (Ces.) Fres. (≡ Passalora penicillata Ces.) was the only species associated with the original description of Cercospora under “Fungi Rhen. Exs., Fasc. II, no. 117” and was therefore considered the type of this generic name in Braun (l.c.). This is, however, not entirely correct since Fuckel (l.c.: no. 120) simultaneously introduced Cercospora ferruginea Fuckel (≡ Passalora ferruginea (Fuckel) U. Braun & Crous). Braun (l.c.) designated C. penicillata as “type species” of Cercospora, and Crous & Braun (l.c.) excluded the second species involved, C. ferruginea, and reallocated it to Passalora Fr. Hence, the designation of C. penicillata must rather be seen as lectotypification. Fuckel (Fungi Rhen. Exs., No. 117. 1863 and in Hedwigia 2: 133. 1863) added f. apii Fuckel to the C. penicillata (often cited as “var. apii ” but definitely introduced as forma), which Fresenius (l.c.) took up and published as C. apii. Braun & al. (in IMA Fungus 6: 420. 2015) have recently re-examined the type of Cercospora, C. depazeoides (Desm.) Sacc. (= C. penicillata), and reallocated it to the genus Pseudocercospora Speg., based on a reassessment of its morphology and phylogenetic position within the Pseudocercospora clade (in Stud. Mycol. 75: 55. 2013). Passalora penicillata (≡ Cercospora penicillata) and Exosporium depazeoides Desm. (≡ Cercospora depazeoides (Desm.) Sacc.) are conspecific, which had been confirmed by re-examinations of the type collections of the two species names (Braun & al., l.c. 2015). The examination of type material of the name of the second species involved, C. ferruginea, led to a reallocation of this species to Passalora. An assignment of C. depazeoides to Pseudocercospora would have serious consequences at the generic level, as Cercospora penicillata (= C. depazeoides) was selected as the type of the generic name Cercospora (Braun, l.c.), making Cercospora an older heterotypic synonym of Pseudocercospora, which is, however, undesirable and would require several hundreds of new combinations. Thus, we prefer a proposal to conserve Cercospora with C. apii as conserved type under the ICN, Art. 14.9 (McNeill & al. in Regnum Veg. 154. 2012), thus rejecting the previously designated type, C. penicillata.