Plastid DNA sequence data of the extinct Logania depressa (Loganiaceae) from New Zealand confirm its generic placement

The generic placement of the enigmatic and extinct Logania depressa from New Zealand has been uncertain due to the paucity of available plant material. This diminutive plant has only been collected once from the central North Island, New Zealand, by William Colenso on 22 February 1847. Logania depressa is dioecious and the single collection comprises only male flowers and does not include female flowers or fruit that feature generic diagnostic characters. Previously its relationship to Geniostoma has been considered and its affinities to Orianthera are unknown. Orianthera has been recently recognised as a segregate of Logania. Using leaf material from a small fragment of L. depressa held in Allan Herbarium (CHR) we recovered 9,368 bp of plastid sequence data that mapped to Mitreola yangchuensis, with Mitreola being the closest generic relative of Logania for which whole genome data was available. Available genetic data for Loganiaceae is limited to several chloroplast markers, including the rps16 intron, petD intron, and petD–petB intergenic spacer. From the novel plastid sequence data for Logania depressa, 48 bp of the rps16 intron, 45 bp of the petD intron and 49 bp of the petD–petB intergenic spacer could be recovered to compare with available Loganiaceae sequences. Phylogenetic analysis of these sequences confirmed L. depressa as the only New Zealand member of Logania sens. str., but its relationships to Australian species are unresolved.