Phyllidia Cuvier, 1797

Papu, Adelfia, Bogdanov, AleXander, Bara, Robert, Kehraus, Stefan, König, Gabriele M., YonoW, Nathalie & Wägele, Heike, 2022, Phyllidiidae (Nudibranchia, Heterobranchia, Gastropoda): an integrative taxonomic approach including chemical analyses, Organisms Diversity & Evolution (New York, N. Y.) 22 (3), pp. 585-629 : 595

Phyllidia Cuvier, 1797

Morphological identification resulted in 11 Phyllidia species (Figs. 4–6), seven of which are recognised species: P. elegans Bergh, 1869 , P. coelestis Bergh, 1905 , P. picta Pruvot-Fol, 1957 , P. exquisita Brunckhorst, 1993 , P. haegeli Fahrner & Beck, 2000 , P. ocellata Cuvier, 1804 , and Phyllidia varicosa Lamarck, 1801 . Two species have been illustrated as new undescribed species in the available literature, Phyllidia sp. 3 and Phyllidia sp. 9 ( Gosliner et al., 2015, 2018). The third new species, which we call Phyllidia sp. a in this work ( Fig. 6.1a ), was figured by Gosliner et al. (2008: 300, top right figure only) and Venkataraman et al. (2015: pl. 75), both as Phyllidiopsis monacha ( Yonow, 1986) , and the same specimen (Phsp17Bu1) was illustrated as Phyllidia sp. in Eisenbarth et al. (2018). A recent corrigendum validated the original generic placement of Phyllidia monacha based on the original description and drawings, in combination with recent photographs of the type specimen ( Yonow, 2021), thereby indicating possibly greater similarities with our new species.

Molecular analyses confirmed our morphologically based assignments of species to a large extent. Our study also confirms that species previously assigned to the genus Fryeria based on their ventral anal opening are part of Phyllidia and do not form a separate clade. Although species are clearly marked by long branches, branch lengths between species are rather short with low bootstrap values ( Figs. 13 , S 1 ). Higher support values are provided for the sister-taxa relationship of P. elegans / P. coelestis (99), P. haegeli / P. sp. 9 (100), and P. ocellata / P. sp. a. However, we would like to emphasise here that statements on relationships between species are preliminary because many recognised worldwide species could not be included in this analysis.

LCMS analyses revealed a range of brominated compounds that occur in several Phyllidia species in addition to commonly encountered sesquiterpene isonitriles. These comprise bromoindole alkaloid 5-bromotryptophan (m/z values 283.006 and 285.005 [M + H] +, and 265.983 and 267.978 [M-NH 3] +) which was detected in all Phyllidia species (Fig. S4b). Obtained MS data perfectly match values in the original description of Smenospongia sp. (Porifera) metabolites by Tasdemir et al. (2002) and allowed confident structure assignment of bromoindoles. In addition, double-charged ions of unidentified polar mono- (m/z 235.020 and 242.029 [M + 2H] 2+) and dibrominated (m/z 219.035 [M + 2H] 2+) compounds with retention times of 3.5–5.5 min were observed in all Phyllidia extracts except those of P. varicosa . Some of these brominated metabolites could be detected in low amounts in the extracts of six other specimens belonging to the genera Phyllidiopsis ( Phyllidiopsis krempfi ) and Phyllidiella ( Phyllidiella sp. c subclade 1, P. zeylanica auctt., and P. rudmani ).

Figures

Fig. 6 Phyllidia species and specimens with identifiers. Scale bars: 10 mm. 1a Phyllidia sp. a: a Phsp17Bu1. 2a–i Phyllidia varicosa: a Phel15Bu1; b Phva15Bu8; c Phel18Bu6; d Phel18Ko3; e Phva18Po1; f Phva18Ba1; g Phva15Bu2; h Phva16Sa37; i Phva16Sa38

Fig.13 Maximum likelihood tree of Phyllidiidae based on the concatenated data set of partial CO1 and 16S sequences. Terminal taxa on species level collapsed. Numbers at nodes are bootstrap values (1000 replicates). The genera are marked with the same colours as in Fig. S1. Numbers behind the species names indicate results of the

Fig. 1 Sampling locations in Sulawesi, Indonesia