Phyllidia varicosa Lamarck, 1801

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 : 601

Phyllidia varicosa Lamarck, 1801

The most frequently collected species was Phyllidia varicosa with 114 specimens, and they were also the largest specimens (up to 87 mm) in our collections. Smaller animals of P. varicosa (Phel15Bu1, Fig. 6.2a : 7 mm) resemble the whiter P. elegans (Phel18Bu2, Fig. 4.1a) and the spikier P. haegeli (Phco5Bu1, Fig. 5.3a). Larger animals have a greater number of simple but acute ridges, and only the tubercles on the median ridges are capped with yellow. The oral tentacles are grey with a faint or bright yellow tip. The foot exhibits a black stripe, which can be broken up in black sections (PhvaBu2, Fig. 6.2g ). Fahrner and Schrödl (2000) have shown that the black pigment on the foot can fade during preservation and thus might lead to misidentification. Adult living specimens of P. varicosa usually curl their lateral mantle rim underneath, and so they look rather elongate on the substrate ( Fig. 6.2f, h, i ). The 130 sequences from our collections combined with those from GenBank are supported as a monophyletic group by a bootstrap value of 100. However, this species, with the highest number of sequences included in our analysis, also has the second greatest intraspecific genetic variability of up to 16% mainly caused by long branches like Phva18LS3 (Table S4).

Extracts of four P. varicosa specimens collected in 2015 from two locations at Bunaken National Park were analysed with LCMS. The metabolomes varied for each locality (Fig. S7d), but the major compounds detected can be assigned to sesquiterpene isonitriles. The herein studied P. varicosa specimens seem to lack chemotaxonomic markers that would allow the clear chemical distinction of P. varicosa from other phyllidiid nudibranchs.

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