Phyllidia cf. babai, Brunckhorst, 1993

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 : 597-599

Phyllidia cf. babai

Two of our specimens with the identifiers Phoc18Ba7 and Phoc16Sa3 (Fig. 5.2a, b) have a very similar colouration to P. ocellata , but actually group with two sequences from Stoffels et al. (2016), who assigned their sequences to Phyllidia cf. babai . This monophyletic clade is supported by a bootstrap value of 100 with an intraspecific genetic variability of 5.67%. The animals that Stoffels et al. (2016) depicted are similar to specimens originally described as P. babai Brunckhorst, 1993 with a white ground colour and only the central row of tubercles being yellow or orange. Brunckhorst (1993) also mentioned a distinct yellow margin for his newly described P. babai , a feature that seems to be lacking in the specimens analysed by Stoffels et al. (2016). We assume that the second specimen depicted in their figure 10e is from a preserved animal and therefore lost the yellow pigment. Our specimens differ from their P. cf. babai specimens by having a yellow or orange background colour identical to both their P. ocellata and our P. ocellata . Moreover, our specimens of this clade have white lines surrounding the black patches that are always continuous between the black rings and form a central white oval line around the three tubercular rows. In P. ocellata , the coloured rings are always separated by the orange background colour (see P. ocellata below). One of our P. cf. babai specimens (Phoc18Ba7, Fig. 5.2a) had an orange foot and orange oral tentacles, and not the typical cream to white ventral colouration of P. babai , nor the darker grey colouration of foot and oral tentacles of P. ocellata . Therefore, our specimens do not match P. cf. babai in colour, although they group with the two sequences of Stoffel et al. (2016); they also do not match the colour description of P. babai in Brunckhorst (1993). Investigation of more specimens is needed to find better distinguishing characters for this molecularly distinct clade, which we retain as P. cf. babai .

Chemical analysis of one P. cf. babai specimen (Phoc16Sa3, Fig. 5.2b; Undap et al., 2019: fig. 3B) and one P. ocellata specimen (Phoc16Sa7, Fig. 5.5e) demonstrates clearly different metabolomes despite external similarities (see Fig. S7c). A unique feature detected only in the metabolome of P. cf. babai among all chemically analysed phyllidiids is a series of polar brominated compounds with m/z values matching masses of the bromopyrrole alkaloids manzacidin A ([M +H] + 344.024 and 346.022) and manzacidin B ([M + H] + 360.017 and 362.014; see Fig. S4b). These ions also form a separate cluster in the GNPS molecular network. Furthermore, a MS 2 spectrum of a peak (m/z 403.917 M +) with a retention time of 4.9 min and an isotopic pattern of a dibrominated compound matched perfectly with the MS 2 spectrum of spongiacidin A in the GNPS library (see Fig. S5). Its monobrominated derivative spongiacidin B (m/z 324.009 M +, retention time of 3.7 min) was also detected. These alkaloids

◂ Fig. 5 Phyllidia species and specimens with identifiers. Scale bars: 10 mm. 1a, b: Phyllidia exquisita : a Phex17Ba1; b Phex18Bl2. 2a, b Phyllidia cf. babai : a Phoc18Ba7; b Phoc16Sa3. 3a–e Phyllidia haegeli : a Phco15Bu1; b Phpic16Sa4; c Phva16Bu2; d Phva16Sa51; e Phva16Sa19. 4a Phyllidia sp. 9 : a Phsp15Bu1. 5a–g Phyllidia ocellata : a Phoc18Ba4; b Phoc15Bu1; c Phoc16Sa2; d Phoc16Sa4; e Phoc16Sa7; f Phoc17Ba1; g Phma16Sa were described from an Okinawan sponge species of the genus Hymeniacidon ( Inaba et al., 1998; Kobayashi et al., 1991). Additionally, the MS/MS spectrum of a dibrominated compound with an m/z 389.938 [M + H] + and retention times of 4.8 and 6.8 min matches the GNPS repository spectrum of dibromophakellin ( Fig. S6 ), an alkaloid from a sponge identified as Acanthella flabellata (Tanita, 1961) ( Sharma & Magdoff-Fairchild, 1977 as Phakellia ). Common sesquiterpene isonitriles and formamides were also detected in the crude extract of P. cf. babai .

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