Flatfishes (Pleuronectiformes) are a species‐rich and distinct group of fishes characterized by cranial asymmetry. Flatfishes occupy a wide diversity of habitats, including the tropical deep‐sea and freshwaters, and often are small‐bodied fishes. Most scientific effort, however, has been focused on large‐bodied temperate marine species important in fisheries. Phylogenetic study of flatfishes has also long been limited in scope and focused on the placement and monophyly of flatfishes. As a result, several questions in systematic biology have persisted that molecular phylogenetic study can answer. We examine the Pleuronectoidei, the largest suborder of Pleuronectiformes with >99% of species diversity of the order, in detail with a multilocus nuclear and mitochondrial data set of 57 pleuronectoids from 13 families covering a wide range of habitats. We combine the molecular data with a morphological matrix to construct a total evidence phylogeny that places fossil flatfishes among extant lineages. Utilizing a time‐calibrated phylogeny, we examine the timing of diversification, area of origin and ancestral temperature preference of Pleuronectoidei. We find polyphyly or paraphyly of two flatfish families, the Paralichthyidae and the Rhombosoleidae, and support the creation of two additional families—Cyclopsettidae and Oncopteridae—to resolve their non‐monophyletic status. Our findings also support the distinctiveness of Paralichthodidae and refine the placement of that lineage. Despite a core fossil record in Europe, the observed recent diversity of pleuronectoids in the Indo‐West Pacific is most likely a result of the Indo‐West Pacific being the area of origin for pleuronectoids and the ancestral temperature preference of flatfishes is most likely tropical.

BIOPAPUA, KAVIENG 2014, MADEEP, PAPUA NIUGINI

Taiwan is a large island in north western Pacific waters with the sea floor connecting to two major deep-sea basins, the eastern waters facing the Pacific Ocean (to 4000 m depth) and linking to the Philippine Basin, whilst south western waters are associated with the South China Sea Basin (up to 1000 m). Previously, the biodiversity of Taiwanese deep-sea barnacles had not been studied extensively, due to a lack of deep-sea expeditions and sampling. Recently, several TAIWAN deep-sea cruises investigated the biodiversity of the deep-sea fauna of Taiwan and sampling was conducted to depths of 4000 m. The present study reports on the biodiversity of the deep-sea barnacles of Taiwan, a total of 18 species. One species was previously recorded from Taiwanese waters and 17 are new records, including two new species belong to the genera Litoscalpellum and Altiverruca.

TAIWAN 2001, TAIWAN 2002, TAIWAN 2004

In recent collections from deep waters around Taiwan, numerous new records of brachyuran crabs were obtained for Taiwan. Thirty-one species are added to the known Taiwanese brachyuran fauna, including 13 new records of genera and two new records of families (Homolodromiidae and Cymonomidae). The established brachyuran crab fauna for Taiwan now stands at 604 species.

TAIWAN 2000, TAIWAN 2001

NanHai 2014

The identity of the mangrove sesarmid crab Clistocoeloma balansae A. Milne-Edwards, 1873, is clarified on the basis of the types from New Caledonia, and fresh material from Vanuatu and the Philippines. Sesarma (Sesarma) tectum Rathbun, 1914, is shown to be a junior subjective synonym of C. balansae A. Milne-Edwards, 1873. A new species, C. melanesicum, superficially similar to C. balansae, is described from Vanuatu, New Caledonia, and, Solomon Islands.

PANGLAO 2004, SANTO 2006

DongSha 2014, NanHai 2014, ZhongSha 2015

The deep-water epialtid spider crab (superfamily Majoidea) material collected from recent French expeditions to Papua New Guinea (BIOPAPUA 2010, PAPUA NIUGINI 2012, MADEEP 2014, and KAVIENG 2014) was studied. In addition to several new records for the country, five new species of Oxypleurodon Miers, 1885, Rochinia A. Milne-Edwards, 1875, and Tunepugettia Ng, Komai & Sato, 2017, are described. The taxonomy of Tunepugettia is reappraised, and a new genus, Crocydocinus n. gen., is established, characterised by its smooth ambulatory legs and a distinct male first gonopod structure. Four species from the Bay of Bengal, Sumatra, and Réunion Island, currently placed in Rochinia and Tunepugettia are transferred to Crocydocinus n. gen. and four new species from Papua New Guinea, Philippines, and Vanuatu are described. A new genus, Neophrys n. gen., with one new species from Papua New Guinea, is established, and is characterised by the supraorbital eave being fused with the carapace and the poorly developed pre-orbital angle.

BIOPAPUA, KAVIENG 2014, MADEEP, PANGLAO 2005, PAPUA NIUGINI, SANTO 2006

The use of phylogeny with uneven or limited taxon sampling may bias our interpretation of organismal evolution, for instance, the origin(s) of the deep-sea animals. The Mollusca is the second most speciose phylum, in which the Gastropoda forms the largest group. However, the currently proposed hypotheses of gastropod phylogeny are mainly based on part of their taxonomic diversity, notably on the large-sized and shallow-water species. In this study, we aimed at correcting this bias by reconstructing the phylogeny with new mitogenomes of deep-sea gastropods including Anatoma sp., Bathysciadiidae sp., Bayerotrochus teramachii, Calliotropis micraulax, Coccocrater sp., Cocculina subcompressa, Lepetodrilus guaymasensis, Peltospira smaragdina, Perotrochus caledonicus, Pseudococculinidae sp., and Shinkailepas briandi. This dataset provided the first reports of the mitogenomes for the Cocculiniformia, three vetigastropod superfamilies: Pleurotomarioidea, Lepetelloidea, and Scissurelloidea, and the neritimorph family Phenacolepadidae. The addition of deep-sea representatives also allowed us to evaluate the evolution of habitat use in gastropods. Our results showed a strongly supported sister-group relationship between the deep-sea lineages Cocculiniformia and Neomphalina. Within the Vetigastropoda, the Pleurotomarioidea was revealed as the sister-group of the remaining vetigastropods. Although this clade was presently restricted to the deep sea, fossil records showed that it has only recently invaded this habitat, thus suggesting that shallow waters was the ancestral habitat for the Vetigastropoda. The deep-sea Lepetelloidea and Lepetodriloidea formed a well-supported clade, with the Scissurelloidea sister to it, suggesting an early transition from shallow water to deep sea in this lineage. In addition, the switch between different chemosynthetic habitats was also observed in deep-sea gastropod lineages, notably in Neomphalina and Lepetelloidea. In both cases, the biogenic substrates appeared as the putative ancestral habitat, confirming the previously proposed hypothesis of a wooden-step to deep-sea vents scenario of evolution of habitat use for these taxa.

AURORA 2007, BIOPAPUA, CONCALIS, EXBODI, NORFOLK 2, PAPUA NIUGINI

With 11 species, the genus Chelidoperca is a small group of teleost fishes belonging to the Serranidae. They are bottom-dwelling fishes living on continental shelves/slopes in offshore areas or on remote seamounts/banks at depths ranging from around 40–400m mostly in the tropical Indo-West Pacific. Over the past few years, efforts have been made to resolve the taxonomy of Chelidoperca, and subsequently four new species were described. However, these recent advances were made with a traditional approach (i.e., morphology) and limited examinable materials, usually preserved specimens, from ichthyological collections. Further investigations are still needed to address the gaps in our knowledge about their diversity, phylogeny, and biogeography. In this study, we collected 65 new samples, mainly during eight biodiversity expeditions carried out between 2007 and 2016 in the West Pacific under the Tropical Deep-Sea Benthos program. Specimens were photographed after collection to record fresh color patterns, which are essential for species diagnosis. Our analytical approach includes state-of-the-art DNA-based methods for species delimitation. The combined evidence from both molecular and morphological examinations, as well as other information such as geography, is used to test species validity. This reveals 15 species, including six new ones. We formally describe herein C. leucostigmata sp. nov., C. microdon sp. nov., and C. barazeri sp. nov. on the basis of specimens collected on Macclesfield Bank in the South China Sea, on the Chesterfield and Island of Pines plateau of New Caledonia, and off the New Ireland Province of Papua New Guinea, respectively. These new species are morphologically distinct from all other known species of Chelidoperca by body color pattern and combinations of a few identified characters. We also redescribe one of the lesser known species, C. lecromi, from fresh specimens collected close to its type locality and a new site in the Coral Sea. The distributional records for this and other known species are updated accordingly. Genetic references of the species as well as an updated identification key to western Pacific species are also provided.

AURORA 2007, BIOPAPUA, EXBODI, KANACONO, KANADEEP, KAVIENG 2014, MADEEP, ZhongSha 2015

The new serranid fish Chelidoperca cerasina is described on the basis of 13 specimens from the Coral Sea (off New Caledonia and eastern Australia), southwest Pacific Ocean, at depths of 245–338 m. The new species can be readily distinguished from all congeners by having the following combination of characters: an orange spot on pectoral-fin and caudal-fin bases; 4 scale rows between lateral line and base of spinous dorsal fin; cheek scales in 8 or 9 (modally 8) rows; tip of upper caudal-fin lobe elongated, slightly longer than lower lobe in specimens > ca. 100 mm; no longitudinal dark stripe or row of dark blotches laterally on body; interorbital scales extending beyond mid-orbit level, but not reaching anterior margin of orbit; scales on ventral surface of lower jaw restricted to angular, absent on dentary; pelvic fin short, tip not reaching anus when adpressed.

CHALCAL 2, EXBODI, KANADEEP, LITHIST, MIRIKY, MUSORSTOM 5

Left-eyed flounders of the genus Chascanopsetta Alcock 1894 (Bothidae) occur in the Indian, Pacific, and Atlantic oceans at depths ranging from 120 to 1500 meters. They possess some unique features in bothid fishes including a strongly compressed and elongated body and a tremendously large mouth. Currently, nine species of Chascanopsetta are recognized, and three of them (C. micrognatha Amaoka & Yamamoto 1984, C. lugubris Alcock 1894 and C. prognatha Norman 1939) are distributed in the West Pacific. We collected 25 specimens of Chascanopsetta during 11 biodiversity expeditions carried out mainly in the West Pacific. Among them, eight specimens taken off Papua New Guinea present morphological features that differ from those of the three nominal species known in the West Pacific. In this study, we examined these eight specimens of unknown affinity and compared their morphology to that of specimens of other congeneric species. Results of these comparisons showed that these specimens represent an undescribed species of Chascanopsetta, named herein, C. novaeguineae sp. nov.. The new species resembles C. elski Foroshchuk 1991, which is known only from the Saya de Malha Bank in the western Indian Ocean, in having a high number of gill rakers (> 13). However, the combination of the following characters further distinguishes C. novaeguineae sp. nov. from C. elski: longer jaws, narrower interorbital width, and number of pseudobranches (21–25 vs. 26–27). The DNA sequences from the mitochondrial cytochrome oxidase subunit I (COI) gene from C. novaeguineae sp. nov. and other species were obtained and compared to confirm its taxonomic status and to infer its tentative phylogenetic position within the Chascanopsetta.

AURORA 2007, BIOPAPUA, DongSha 2014, KANACONO, KANADEEP, KARUBENTHOS 2, KAVIENG 2014, MADEEP, NanHai 2014, SALOMONBOA 3, ZhongSha 2015