Phanerophthalmus is a genus of Indo-West Pacific sea slugs inhabiting seagrass and coral reefs with up to now seven species currently recognised as valid. The goals of this study are to revise the systematics of Phanerophthalmus, infer its phylogeny and patterns of diversity, as well as study its diet. Morphology was combined with molecular phylogenetics based on two mitochondrial (cytochrome c oxidase subunit I, 16S rRNA) and one nuclear (28S rRNA) genes. Molecular species delimitation methods (ABGD, DISSECT) were employed to aid delimiting species. Diet was assessed by gut content analysis. Seventeen species were recognised, 10 of them new to science (P. albotriangulatum, sp. nov., P. anettae, sp. nov., P. batangas, sp. nov., P. boucheti, sp. nov., P. cerverai, sp. nov., P. lentigines, sp. nov., P. paulayi, sp. nov., P. purpura, sp. nov., P. rudmani, sp. nov., P. tibiricae, sp. nov.). Phanerophthalmus has its highest diversity in the Western Pacific where 13 species occur with a peak in the Coral Triangle (11 species; three only known from here). Diversity decreases towards the Central Pacific with five species and Indian Ocean/Red Sea with four species. Only two species are distributed across the Indo-West Pacific. Preliminary gut content analysis suggests these slugs feed on diatoms.

ATIMO VATAE, PANGLAO 2004

Absence of resolution in phylogenetic trees, or metaphyly, is a common phenomenon. It mainly results from the fact that each data set has its own limit and can hardly be expected to reconstruct alone an entire hierarchy. Because metaphyly helps point out which regions of a tree merit further investigation, one should not avoid metaphyly but rather should try to detect it by addressing carefully node reliability. In this paper we explore the implication of Inetaphyly for species names. We present a phylogenetic analysis of Discodorididae (Mollusca, Gastropoda, Nudibranchia, Doridina), with an emphasis on relationships among species of Discodoris and its traditionally close 'allies' such as Peltodoris and Anisodoris. We demonstrate that some species must be transferred to different discodoridid subclades with which they share synapomorphies, but that many species form a metaphyletic group At the base of Discodorididae, and therefore cannot be placed in any taxon of genus level. We demonstrate that the current International Code of Zoological Nomenclature does not allow taxonomists to handle this situation because it requires selecting a taxon name of genus rank for every species binomial. Then we evaluate the results provided by new forms of species names, both in a rank-based system, such as the current nomenclature, and a rank-free system. All solutions considered would cause radical changes to the 'spirit' of the current ICZN (and, by extension, to the other current codes). In a rank-free system of nomenclature, such as the PhyloCode, the best result is obtained with an epithet-based form that does not mention supra-specific relationships. Under this method, official species names would take the form 'boboliensis Bergh, 1877', although page numbers and letters can be added for uniqueness purposes. Taxonomists would then be free to add supra-specific taxon names in 'common' species names, such as Discodorididae boholiensis Bergh, 1877 or simply Discodorididae boboliensis. Here we wish to stimulate discussion of a problem that we believe merits wide debate: absence of resolution in phylogenetic reconstruction and its impact on species nomenclature.

HALIPRO 1, MONTROUZIER

In this paper, a new genus in the nudibranch family Discodorididae, Avaldesia n. gen., is established for Avaldesia albomacula (Chan & Gosliner, 2007) and Avaldesia tahala (Chan & Gosliner, 2007), originally assigned to the genus Thordisa Bergh, 1877, and a new species, Avaldesia tamatoa n. sp., described here from the central Pacific. To establish species relationships within Avaldesia, as well as the placement of Avaldesia within Discodorididae, we utilized four molecular markers (cytochrome c oxidase subunit I, 16S rRNA, histone H3 and 28S rRNA) in our Bayesian inference and maximum likelihood analyses. Four species delimitation methods were complemented by morphological dissections and scanning electron microscopy. Our results reveal a clear separation between Avaldesia and Thordisa and suggest that Avaldesia is more closely related to the genera Hoplodoris Bergh, 1880 and Asteronotus Ehrenberg, 1831. The most characteristic features of Avaldesia include a radula with increasing denticulation towards the fimbriate outermost laterals and a reproductive system with a lobate vestibular gland, occasional hollow vestibular spine and a penis armed with one or more penial spines. All species of Avaldesia are found in shallow water (5–10 m depth) on rocky reefs, sandy sediments and algal fields with distributions across the Indo-Pacific.

PAPUA NIUGINI

The Indo-Pacific genus Halgerda Bergh, 1880a is one of the most diverse and better-studied genera within the nudibranch family Discodorididae. Previous studies have been predominantly based on morphology; however, the addition of molecular data has led to new species descriptions as well as unresolved species complexes. Here, we broaden the available molecular data within Halgerda by utilizing two mitochondrial and two nuclear genes in coordination with morphology to describe 14 new Halgerda species. Bayesian inference, maximum likelihood, and species delimitation analyses were used to clarify previously established relationships and evaluate the new species positions within Halgerda. Based on our results Halgerda elegans Bergh, 1905 is synonymized with Halgerda willeyi Eliot, 1904 and new descriptions for Halgerda mango sp. nov., Halgerda berberiani sp. nov., Halgerda biqiea sp. nov., Halgerda paulayi sp. nov., Halgerda labyrinthus sp. nov., Halgerda anosy sp. nov., Halgerda mesophotica sp. nov., Halgerda profunda sp. nov., Halgerda takipsilim sp. nov., Halgerda scripta sp. nov., Halgerda hervei sp. nov., Halgerda maaikeae sp. nov., Halgerda pattiae sp. nov., and Halgerda radamaensis sp. nov. are provided here. We also provide an updated morphological description for juvenile specimens of Halgerda dalanghita Fahey & Gosliner, 1999a; expand upon the two unresolved species complexes previously identified in Tibiriçá et al. (2018); and identify a new mesophotic clade in the Central Pacific.

Restreint, PAPUA NIUGINI

The genus Platydoris Bergh, 1877 is characterized by a at body, wide mantle margin, and elevated branchial and rhinophoral sheaths. Examination of a number of specimens and a review of the literature have shown that there are at least 20 valid species of the genus Platydoris world-wide. Some of them have previously been described by other authors and are redescribed or discussed here: P. argo, P. scabra, P. cruenta, P. angustipes, P. ellioti, P. formosa, P. inframaculata, P. pulchra, P. sanguinea, P. townsendi, P. capricornensis, P. esakii, P. macfarlandi, P. galbanus, P. carolynae. Six new species are described here: P. inornata, P. ocellata, P. annulata, P. sabulosa, P. cinereobranchiata, P. rolani. Platydoris tabulata is a nomen dubium. Species removed from Platydoris include: Doris hepatica, D. murrea, P. variegata, P. punctatella, P. papillata, P. spinulosa, P. carinata, P. immonda, P. spongilla, P. maculata, P. stomascuta. A phylogenetic analysis was conducted, showing the genus to be monophyletic. There was strong support for a clade of all species of Platydoris included in the analysis except for the nodes containing P. annulata and P. macfarlandi, which are found in deeper water than the rest of the genus. This major clade was further divided into a clade of Atlantic and Eastern Pacific species and a clade of IndoPaci c species, showing a strong biogeographical trend. Important characters separating the clades include ventral pigment around the foot, large ventral spots, the presence of vaginal hooks, and whether the accessory gland enters the atrium on the side of the vagina, the side of the deferent duct, or between the two.

MUSORSTOM 2

ATIMO VATAE, PANGLAO 2004, PAPUA NIUGINI

Four new species of Halgerda from the deep western Pacific Ocean are described. Halgerda fibra n. sp. was found in the Philippines at depths near 90 m and is also recorded from the New Caledonia region in 90-400 m. The new species differs from other Halgerda in its reproductive morphology. The ampulla is larger and more coiled than other Halgerda and the vagina is also much larger and more bulbous than other members of the genus. Halgerda abyssicola n. sp. was found near Vanuatu at depths of 207-280 m and from the Coral Sea in 385-420 m. Its reproductive morphology is unusual for a species of Halgerda in that the penis and vagina are both extremely large and bulbous. Halgerda azteca n. sp. was found near Norfolk Ridge, south of New Caledonia at depths from 230-367 m. Its reproductive morphology differs from other Halgerda species primarily due to its long, coiled ejaculatory duct and prominent vaginal sphincter. Halgerda orstomi n. sp. was found near Vanuatu at depths between 160-251 m; from the Philippines at 92-95 m and from New Caledonia at 120 m. Halgerda orstomi has an unusual vaginal sphincter and bulbous vagina which distinguishes it from other Halgerda species. The ranges and depths of three additional, previously described Halgerda species: H. brunneomaculata Carlson & Hoff, 1993, H. carlsoni Rudman, 1978 and H. dalanghita Fahey & Gosliner, 1999 are also extended.

BATHUS 3, MUSORSTOM 10, MUSORSTOM 3, MUSORSTOM 4, MUSORSTOM 5, MUSORSTOM 8, SMIB 4, SMIB 8

KOUMAC 2.1, KOUMAC 2.2, KOUMAC 2.3, PAKAIHI I TE MOANA, PANGLAO 2004

Molecular and morphological evidence support the view that the widely distributed species Berthella stellata (Risso, 1826) is a species complex of at least eight different species. The closely related species Berthella plumula (Montagu, 1803), examined for comparison, is also a complex of two species; the name B. plumula is retained for the Atlantic species and the name Berthella perforata (Philippi, 1844) is proposed for the Mediterranean species. The B. stellata species complex forms a monophyletic group when the Eastern Pacific species Berthella strongi (MacFarland, 1966) is included. Based on a critical review of the literature, the name Berthella stellata is retained for the Eastern Atlantic and Mediterranean species, and the name Berthella pellucida (Pease, 1860) is resurrected for a species found in the Hawaiian Islands. Two new species from the Caribbean region (Berthella nebula sp. nov., Berthella vialactea sp. nov.) and one from the Eastern Pacific (Berthella andromeda sp. nov.) are described herein, but the status of the Brazilian species B. tupala Er. Marcus, 1957 remains uncertain. Two possible new species from the Eastern Pacific, represented by one specimen each, were recovered in the phylogenetic analyses but not formally described. It is hypothesized that additional species of this complex may occur in other parts of the Indo-Pacific tropics, particularly in the Indian Ocean.

KOUMAC 2.1

PANGLAO 2004

SANTO 2006

PAPUA NIUGINI

Nudibranchs are charismatic marine gastropods that lack a shell in the adult stage. While most nudibranchs feed on sessile animals such as sponges, bryozoans, and cnidarians, the nudibranch genus Gymnodoris Stimpson, 1855 evolved a more active and predatory lifestyle, including sea slug predation, cannibalism, and oddly enough, fish-fin parasitism. At the beginning of our work, no phylogenetic hypothesis existed for the genus, nor a clear picture of how Gymnodoris is related to other nudibranchs. Here we set out to reconstruct Gymnodoris phylogeny, investigate species diversity, and clarify the status of the genus name Analogium, which had been proposed for members of the genus with a linear gill filament arrangement. We present the first phylogenetic hypothesis for Gymnodoris, reconstructed by maximum likelihood and Bayesian inference using two mitochondrial and two nuclear loci, with gill filament arrangement plotted on the phylogeny. The backbone of the phylogeny remains unresolved with theseloci, however, we found that Gymnodoris comprises three main well-supported clades, which we refer to as the “subornata”, “citrina” and “varied” clade, the latter two clades being comprised of several well-supported subclades. The sister group to Gymnodoris is a clade including the genera Vayssierea and Lecithophorus. Based on ABGD and PTP species delimitation methods, we conservatively estimate 65–70 species comprise our dataset. We further estimate that approximately 81% of the species we sampled are undescribed, and note that a linear gill filament arrangement has evolved multiple times within the genus. Gymnodoris is only monophyletic when the species with a linear gill arrangement are included. Therefore, at this time, we agree with the synonymy of Analogium striata with Gymnodoris striata by Rudman and Darvell (1990) and that the genus name Analogium is warranted as a junior synonym of Gymnodoris. Given the extensive undescribed diversity, and lack of resolution at some of the nodes in the phylogeny, patterns of diversification in diet are impossible to discern at this time and will require a large effort to both describe Gymnodoris species diversity and the diets of these candidate species.

PAPUA NIUGINI

SANTO 2006

PANGLAO 2004

Species identities of Goniobranchus nudibranchs with white bodies and various marginal bands have long been problematic. In this study, specimens of these Goniobranchus nudibranchs from the Philippines, Peninsular Malaysia, Japan, Papua New Guinea, and Madagascar were analyzed and molecular data were obtained in order to re-examine the relationships between species within this “white Goniobranchus with marginal bands” group. The analyses clearly recovered six species groups corresponding to the described species Goniobranchus albonares, G. preciosus, G. rubrocornutus, G. sinensis, and G. verrieri as well as one new species, G. fabulus Soong & Gosliner, sp. nov. Notably, G. preciosus, G. sinensis, G. rubrocornutus, G. verrieri, and G. fabulus Soong & Gosliner, sp. nov. exhibit color variation and polymorphism, suggesting that some aspects of color patterns (e.g., presence or absence of dorsal spots) may not always be useful in the identification of species in the “white Goniobranchus with marginal bands” group, whereas other features such as gill and rhinophore colors and the arrangement and colors of the mantle marginal bands are more diagnostic for each species.

ATIMO VATAE, PAPUA NIUGINI

The phylogenetic relationships of the caryophyllidia-bearing dorids are studied, based on the examination of the type species of all the genera previously described. The phylogenetic hypothesis supports that the caryophyllidia-bearing dorids are a monophyletic group and the sister group of the clade formed by Asteronotus Ehrenberg, 1831 and Halgerda Bergh, 1880. Several genera previously considered as valid or regarded as uncertain are here synonymized: Peronodoris Bergh, 1904, Trippa Bergh, 1877, Phlegmodoris Bergh, 1878, Petelodoris Bergh, 1881, Kentrodoris Bergh, 1876, Audura Bergh, 1878, Centrodoris P. Fischer, 1883, Anisodoris Bergh, 1898, Awuka Er. Marcus, 1955, Rhabdochila P. Fischer, 1883, Boreodoris Odhner, 1939, Dictyodoris Bergh, 1880, Gravieria Vayssière, 1912, Aporodoris Ihering, 1886. The following genera are regarded as valid: Asteronotus, Atagema J.E. Gray, 1850, Jorunna Bergh, 1876, Platydoris Bergh, 1877, Diaulula Bergh, 1878, Rostanga Bergh, 1879, Halgerda Bergh, 1880, Baptodoris Bergh, 1884, Gargamella Bergh, 1894, Alloiodoris Bergh, 1904, Sclerodoris Eliot, 1904, Taringa Er. Marcus, 1955, Thorybopus Bouchet, 1977. The new genus Nophodoris is described based on two new species from New Caledonia deep waters. Two additional new species from New Caledonia belonging to the genera Atagema and Gargamella are also described. Nomenclatural and taxonomic problems are discussed, and several type species, neotypes and lectotypes are selected.

BATHUS 1, BATHUS 3, Restreint, MUSORSTOM 8, SMIB 8