Table 1.
Literature records of Okenia taxa known from the Mediterranean Sea (valid taxa marked in bold), with type locality or listed localities (TL), Mediterranean records based on concrete material, presence in recent (1990–now) review/books listing Mediterranean biota as a whole (R/B), and notes (N).
Numbers as in Fig 1.
Fig 1.
Okenia taxa recorded from the Mediterranean Sea.
Locality numbers as in Table 1. Type localities of species described from the Mediterranean Sea marked with a red dot. When the exact locality was unknown, a dot was placed in the middle of the sighting area accompanied by a question mark.
Table 2.
Okenia specimens from the Mediterranean Sea recently collected and used in the present study.
Species, number of specimens (N), vouchers, locality and coordinates, collector, and collection date.
Table 3.
Species (authorities not included) used for molecular analyses, voucher, locality, and GenBank accession numbers.
Specimens sequenced during the present study marked with an asterisk.
Fig 2.
Phylogenetic relationships (BI, ML) based on the concatenated mitochondrial (COI and 16S rRNA) and nuclear (H3) genes.
Orange circle indicates Goniodorididae taxa. Pink branches represent Okenia taxa. Okenia species living in the Mediterranean Sea highlighted in blue. New species identified in the present study highlighted in yellow. Different colours highlighted in bPTP and ABGD species delimitation analyses represent potential different taxa.
Table 4.
COI and H3 gene pairwise uncorrected p-distances (%) amongst different species of Okenia and Goniodoris.
Fig 3.
A. Specimen from Lago di Sabaudia (Italy). Photograph by A. Macali. B. Specimen from La Grande-Motte (France). Photograph by D. Minchin. C. Egg-masses on Amathia verticillata from La Grande-Motte (France). Photograph by D. Minchin. D. Specimen from Mar Piccolo, Taranto (Italy). Photograph by G. Colucci. Size (alcohol-preserved specimens) ~9 mm maximum length.
Fig 4.
Internal anatomy. A. Buccal bulb. B. Female portion of the reproductive system. C. Male portion of the reproductive system. D. Reproductive system extended. Abbreviations: am, ampulla; bc, bursa copulatrix; bp, buccal pump; fgm, female gland mass; hd, hermaphroditic duct; oe, oesophagus; og, oral glands; pr, prostate; ra, radular sac; rs, receptaculum seminis; sgl, salivary gland; ud, uterine duct; va, vagina; vd, vas deferens. Scale bars: 1 mm.
Fig 5.
Scanning electron micrographs (SEM) and light microscope photographs (LMP). A. SEM. Detail of jaw elements (SZN-MOL0019). B. LMP. Detail of cuticle elements surrounding lips (SZN-MOL0006). C. SEM. Frontal view of entire radula (MNCN15.05/88169). D. SEM. Frontal view of radula. Detail of rachis, internal, and external teeth (MNCN15.05/88172). E. SEM. Detail of internal teeth (MNCN15.05/88172). F. SEM. Detail of external teeth (MNCN15.05/200036). Scale bars: A, 10 μm; B, 10 μm; C, 300 μm; D, 50 μm; E, 30 μm; F, 30 μm.
Fig 6.
Light microscope photographs (LMP). A. Distal part of the penis, with penial spines (MNCN15.05/200040). B. Vas deferent with penial spines (SZN-MOL0005). Scale bars: 1mm.
Table 5.
Differences between Okenia longiductis sp. nov., Okenia angelensis, and Okenia zoobotryon.
Data after Smallwood [9,9], Pola [100], Lance [10,8], Gosliner & Bertsch [3], and present study.
Fig 7.
Okenia problematica sp. nov. Living animals from Gallipoli (Italy).
A. Holotype (MNCN15.05/200034); B. Paratype (SZN-MOL0001). Photographs by F. Vitale. Size (alcohol-preserved specimens) ~2.5 mm maximum length.
Fig 8.
Okenia problematica sp. nov. Internal anatomy.
A. Buccal bulb. B. Reproductive system. Abbreviations: am, ampulla; bc, bursa copulatrix; bp, buccal pump; fgm, female gland mass; hd, hermaphroditic duct; oe, oesophagus; ra, radular sac; rs, receptaculum seminis; sgl, salivary gland; ud, uterine duct; va, vagina; vd, vas deferens. Scale bars: 1 mm.
Fig 9.
Okenia problematica sp. nov. Scanning electron micrographs (SEM) and light microscope photographs (LMP).
A. SEM. Frontal view of radula. Detail of rachis, internal, and external teeth (MNCN15.05/200034). B. SEM. Detail of internal and external lateral teeth (MNCN15.05/200034). C. SEM. Detail of internal teeth (SZN-MOL0002). D. SEM. Detail of external tooth (SZN-MOL0002). E. LMF. Detail of penial spines (MNCN15.05/200034). F. SEM. Detail of penial spines (SZN-MOL0002). Scale bars: A, 50 μm; B, 30 μm; C, 20 μm; D, 10 μm; E, 10 μm; F, 20 μm.
Table 6.
Differences between Okenia problematica sp. nov., Okenia cupella, and Okenia impexa.
Data after Marcus [9,7], Vogel & Schultz [9,4], Sales et al. [11,3], and present study.
Fig 10.
Okenia cupella (holotype, USNM 679396).
Lateral views of the specimen.
Fig 11.
Okenia cupella (holotype, USNM 679396).
Internal anatomy. A. Buccal bulb. B. Reproductive system. Abbreviations: am, ampulla; bc, bursa copulatrix; bp, buccal pump; fgm, female gland mass; hd, hermaphroditic duct; oe, oesophagus; ra, radular sac; rs, receptaculum seminis; sgl, salivary gland; ud, uterine duct; va, vagina; vd, vas deferens. Scale bars: 1 mm.
Fig 12.
Okenia cupella (holotype, USNM 679396).
Scanning electron micrographs (SEM) and light microscope photographs (LMP). A. LMF. Radula. B. SEM. Detail of penial spines. Scale bars: 10 μm.
Fig 13.
Old and new Mediterranean Okenia assemblage.
Okenia elegans. Miramare (Trieste, Italy) [65–66]. Photo: D. Poloniato. Okenia hispanica. Holotype. Estepona (Malaga, Spain) [52, 74]. Photo: D. Moreno/Fauna Ibérica (MNCN-CSIC). Okenia leachii. Eilean Siar (Great Britain) [74]. Photo: B. Picton. Okenia mediterranea. Santa Maria al Bagno (Lecce, Italy) (Table 2: MNCN15.05/88174). Photo: F. Vitale. Okenia aspersa. Noli (Savona, Italy) [19, 91]. Photo: F. Betti. Okenia problematica sp. nov. (= Okenia cupella/impexa sensu AA [18, 52, 54, 57, 85, 95, 98]). Gallipoli (Italy) (Table 4: MNCN15.05/200034). Photo: F. Vitale. Okenia longiductis sp. nov. (= Okenia zoobotryon sensu AA [54, 74, 101]). Lago di Sabaudia (Italy) (Table 2). Photo: A. Macali.
Table 7.
Comparative table highlighting main external diagnostic characters and radular formula of Okenia species living in the Mediterranean Sea.