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Imagery has become a key tool for assessing deep-sea megafaunal biodiversity, historically based on physical sampling using fishing gears. Image datasets provide quantitative and repeatable estimates, small-scale spatial patterns and habitat descriptions. However, taxon identification from images is challenging and often relies on morphotypes without considering a taxonomic framework. Taxon identification is particularly challenging in regions where the fauna is poorly known and/or highly diverse. Furthermore, the efficiency of imagery and physical sampling may vary among habitat types. Here, we compared biodiversity metrics (alpha and gamma diversity, composition) based on physical sampling (dredging and trawling) and towed-camera still images (1) along the upper continental slope of Papua New Guinea (sedimented slope with wood-falls, a canyon and cold seeps), and (2) on the outer slopes of the volcanic islands of Mayotte, dominated by hard bottoms. The comparison was done on selected taxa (Pisces, Crustacea, Echinoidea, and Asteroidea), which are good candidates for identification from images. Taxonomic identification ranks obtained for the images varied among these taxa (e.g., family/order for fishes, genus for echinoderms). At these ranks, imagery provided a higher taxonomic richness for hard-bottom and complex habitats, partially explained by the poor performance of trawling on these rough substrates. For the same reason, the gamma diversity of Pisces and Crustacea was also higher from images, but no difference was observed for echinoderms. On soft bottoms, physical sampling provided higher alpha and gamma diversity for fishes and crustaceans, but these differences tended to decrease for crustaceans identified to the species/morphospecies level from images. Physical sampling and imagery were selective against some taxa (e.g., according to size or behavior), therefore providing different facets of biodiversity. In addition, specimens collected at a larger scale facilitated megafauna identification from images. Based on this complementary approach, we propose a robust methodology for image-based faunal identification relying on a taxonomic framework, from collaborative work with taxonomists. An original outcome of this collaborative work is the creation of identification keys dedicated specifically to in situ images and which take into account the state of the taxonomic knowledge for the explored sites.

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Trachinocephalus gauguini Polanco, Acero & Betancur, 2016, new record Figure 1A���B; Table 1���2 Material examined. NTUM 11085 (tissue voucher: PNG 3127) and NTUM 11212 (tissue voucher: PNG 3163). Both specimens were collected from mid-shelf areas around 20 km west of Kavieng, New Ireland Province, Papua New Guinea (Fig. 2) on September 2, 2014 by R/V ALIS from station CP4455, 2�� 23.4' S, 150�� 37' E, 60���72m, and station CP4456, 2��35' S, 150��40' E, 134���144m, respectively (campaign: KAVIENG 2014). Diagnosis. Morphometric data and meristic data for the two Papua New Guinea specimens are as in Table 1 and 2 respectively. The morphological characteristics fit within the range of the identification key, description of body color pattern, and photographs provided in Polanco et al. (2016): L Sn 6.7���10.0% of HL, L Sn 12.6���18.9% of D B, L Sn 31.6���51.7% of D E, W I 4.0���6.7% of HL; pectoral fin rays 11, anal fin rays 14���16; pectoral, caudal and anal fin yellow; dorsal fin dark yellow; four obvious yellow stripes along the body longitudinally, with several inconspicuous vertical bars across; an oval black spot above the dorsal border of the operculum, and a rather wide dark blotch below the eye (indistinct in NTUM 11212) (Fig. 1A, B). A blunter snout and broader dark blotch beneath the eye distinguish Trachinocephalus gauguini from other species of Trachinocephalus., Published as part of Wang, Shih-Yu, Chen, Jhen-Nien, Russell, Barry C. & Chen, Wei-Jen, 2018, First record of Gauguin's blunt-nose lizardfish, Trachinocephalus gauguini Polanco, Acero & Betancur 2016 (Teleostei: Synodontidae) outside the Marquesas Archipelago, pp. 151-156 in Zootaxa 4476 (1) on page 152, DOI: 10.11646/zootaxa.4476.1.14, http://zenodo.org/record/1440416, {"references":["Polanco, F. A., Acero, P. A. & Betancur-R., R. (2016) No longer a circumtropical species: revision of the lizardfishes in the Trachinocephalus myops species complex, with description of a new species from the Marquesas Islands. Journal of Fish Biology, 89 (2), 1302 - 1323. https: // doi. org / 10.1111 / jfb. 13038"]}

Trachinocephalus trachinus (Temminck & Schlegel 1846) Figure 1C; Table 1–2 Material examined. NTUM 11201 (tissue voucher: PNG 3126), specimen collected from the same site as T. gauguini, NTUM 11085 (see above). Diagnosis. Morphometric and meristic data for the Papua New Guinea specimen is in Table 1 and 2 respectively. According to the diagnosis provided in Polanco et al. (2016), this species can be distinguished from other two Trachinocephalus species by the following meristic characteristics: L Sn 50.89% of D E; L Sn 19.71% of D B; W I 6.5% of HL; D E 22.36 % of HL; length of the last dorsal ray 10.09% of L S; anal rays 13; pectoral rays 12; predorsal scales 17. This specimen is a transitional juvenile with black peritoneum spots still faintly visible. The pectoral, caudal and anal fin yellow, while dorsal fin dark yellow. Several yellow stripes along the trunk longitudinally, with the most obvious one across the middle part of the body. An oval black spot above the dorsal border of the operculum. Indistinct dark spot below the eye. The morphological data of the Papua New Guinea specimen matches the description of T. trachinus (Table 1, 2; Fig. 1C). The genetic pairwise distance analysis based on COI sequences shows high interspecific variation between T. gauguini and T. trachinus (p -distance: 0.13944–0.14053) while low intraspecific variation within T. gauguini specimens (p -distance: 0-0.00157) (Table 3). This result supports the morphological diagnosis of the three specimens and confirms their species status. Remarks. In a checklist of the marine and estuarine fishes of the Madang District, Papua New Guinea (Fricke et al. 2014), recorded eight synodontid species. One of these was identified as Trachinocephalus “ myops ” based on material deposited in the Australian Museum (AMS) and Western Australian Museum (WAM). It should be noted that T. myops is a species complex and following Polanco et al. (2016) we apply the name T. trachinus for T. “ myops ” populations from the Indo-West Pacific. Our study additionally records T. trachinus from New Ireland, and extends the distribution of T. gauguini from its previously reported area (Marquesas Archipelago) to the western Pacific (Papua New Guinea). Our work shows that Trachinocephalus trachinus and T. gauguini occur sympatrically in Papua New Guinea waters, and as both were collected from the station CP4455, we can confirm that these two species share the same habitat., Published as part of Wang, Shih-Yu, Chen, Jhen-Nien, Russell, Barry C. & Chen, Wei-Jen, 2018, First record of Gauguin's blunt-nose lizardfish, Trachinocephalus gauguini Polanco, Acero & Betancur 2016 (Teleostei: Synodontidae) outside the Marquesas Archipelago, pp. 151-156 in Zootaxa 4476 (1) on pages 152-154, DOI: 10.11646/zootaxa.4476.1.14, http://zenodo.org/record/1440416, {"references":["Polanco, F. A., Acero, P. A. & Betancur-R., R. (2016) No longer a circumtropical species: revision of the lizardfishes in the Trachinocephalus myops species complex, with description of a new species from the Marquesas Islands. Journal of Fish Biology, 89 (2), 1302 - 1323. https: // doi. org / 10.1111 / jfb. 13038","Fricke, R., Allen, G. R., Andrefouet, S., Chen, W. - J., Hamel, M. A., Laboute, P. Mana, R., Hui, T. H. & Uyeno, D. (2014) Checklist of the marine and estuarine fishes of Madang District, Papua New Guinea, western Pacific Ocean, with 820 new records. Zootaxa, 3832 (1), 1 - 247. https: // doi. org / 10.11646 / zootaxa. 3832.1.1"]}

The unusual clingfish Protogobiesox asymmetricus n. gen, n. sp. is described on the basis of four specimens collected in deep water off the north coast of Papua New Guinea in 2012. The species is characterized by its 9-10 dorsal rays, 8 anal rays, 17-24 pectoral-fin rays, 15 principal caudal-fin rays, 3 gills, third arch with 3 gill rakers, 34-35 total vertebrae, with asymmetrical lateral bending starting behind the skull, bent at an angle of 858-928; skull asymmetrical in frontal view; skin naked, surface of head and body without striae; disc without adhesive papillae. A new subfamily Protogobiesocinae is described for this species and Lepadicyathus mendeleevi Prokofiev, 2005, which is redescribed. The new subfamily is compared within the family; keys to the subfamilies of Gobiesocidae and the species within the new subfamily are presented; its phylogenetic relationship to other gobiesocids is inferred based on a multi-locus DNA dataset., Le porte-écuelle insolite Protogobiesox asymmetricus n. gen, n. sp. est décrit à partir de quatre spécimens collectés en 2012 dans les eaux profondes au large de la côte nord de la Papouasie-Nouvelle-Guinée. L’espèce se caractérise par sa nageoire dorsale avec 9–10 rayons, sa nageoire anale avec 8 rayons, sa nageoire pectorale avec 17–24 rayons, 15 rayons principaux sur la nageoire caudale, 3 branchies, un troisième arc branchial avec 3 branchiospines, une colonne vertébrale avec un total de 34–35 vertèbres, le corps arrière du crâne présentant une pré-asymétrie latérale et plié à un angle de 85°–92, un crâne asymétrique en vue de face, une peau nue, une surface de tête et un corps sans stries, un disque sans papille adhésive. Une nouvelle sous-famille, les Protogobiesocinae, est décrite pour cette espèce, et Lepadicyathus mendeleevi Prokofiev 2005 est décrit à nouveau. La nouvelle sous-famille est comparée aux autres membres de la famille; des clés pour les sous-familles de Gobiesocidae et les espèces incluses dans cette nouvelle sous-famille sont présentées ; sa relation de parenté au sein des gobiesocidés est inférée à partir d’un jeu de données ADN multi-locus.