New records and species of deep-sea squat lobsters (Galatheoidea, Munidopsidae) from the Hawaiian Archipelago: an integrative approach using micro-CT and barcodes.

The Hawaiian Archipelago remains extensively under-sampled for many marine invertebrate taxa, including squat lobsters. During the last few years, several deep-sea expeditions carried out in the Pacific Ocean have conducted opportunistic collections of specimens and image data from the vicinity of Hawai'i. Here we describe a new species: Munidopsis hawaii sp. nov. and provide new records for Munidopsidae in the Archipelago and its associations. We illustrate and describe the new species using an integrative approach including micro-CT 3D imaging. Phylogenetic analyses of the species collected from seamounts from Hawai'i indicate that the new species represents a divergent lineage compared to morphologically similar species such as M. dispar and M. papanui. We also study the genetic distances for the species recorded in Hawai'i and other populations of the same species in the adjacent West Pacific. Three species are now known in the Hawaiian region. We also compiled identifications from images captured with ROVs in the area. These observations suggest that munidopsid species are common in the deep sea of Hawaiian waters below 1,000 m.

Two new species of Petalophthalmus and Ipirophthalmus (Crustacea: Mysida: Petalophthalmidae), from New Zealand.

Two new deep-water mysids from the subfamily Petalophthalminae (Crustacea: Mysida: Petalophthalmidae) are described from specimens collected from Challenger Plateau, Chatham Rise, and off the east coast of the North Island of New Zealand. These new species raise the number of species of both genera to five. Petalophthalmus lobatus sp. nov. differs from its congeners by the structure of an elongated ventilation lobe on the seventh oostegites, laterally flattened eyes, and the armature of the telson. Ipirophthalmus crusulus sp. nov. can easily be distinguished by the rudimentary sixth to eighth thoracic endopods. Both species were found to be the prey of several fishes, including commercially caught species, providing insight into their ecology. An identification key to the subfamily is provided.

The squat lobster genus Phylladiorhynchus Baba, 1969 in New Zealand and eastern Australia, with description of six new species.

The small galatheid squat lobster genus Phylladiorhynchus currently contains five species, three of which supposedly have wide Indo-Pacific distributions. To date, two putatively widespread species, P. pusillus and P. integrirostris have been recorded from New Zealand and Australian waters. Here, we review the New Zealand and eastern Australian species of Phylladiorhynchus based on extensive collections from the region using morphological and molecular data. The type species, P. pusillus (Henderson, 1885) (type locality: Twofold Bay, Australia) is redescribed and shown to occur on both sides of the Tasman Sea. Phylladiorhynchus integrirostris, for which the original Hawaiian type material has been lost, is redescribed based on a neotype and shown not to occur in New Zealand or Australian waters, previous records being referable to other species. Six new species of Phylladiorhynchus are described. Seven species of Phylladiorhynchus are now known from New Zealand and eastern Australia. A key to all species of the genus is provided. Results of the present study show that the regional diversity of Phylladiorhynchus is significantly higher than previously reported and demonstrates the utility of a number of subtle morphological characters as diagnostic of species.

Development and characterization of 20 polymorphic microsatellite loci in the deep sea squat lobster, Munida isos Ahyong and Poore, 2004 and cross-amplification in two congeneric species.

Munida isos is a deep sea squat lobster species that is widely distributed across the New Zealand and east Australian region, and is often associated with deep sea vulnerable marine ecosystems. To investigate its population genetic structure and patterns of regional connectivity, microsatellite loci were developed for M. isos from two genomic libraries using the Illumina HiSeq 2500 sequencing platform. Twenty-six loci amplified consistently in M. isos from the Tasman Sea, among which 20 were polymorphic and selectively neutral. Evidence of null alleles was observed at eight loci. Most loci exhibited moderate to high levels of polymorphism, with an average polymorphic information content value of 0.482. The mean number of alleles per locus was 7.45, with a mean expected heterozygosity of 0.520. Thirteen loci exhibited significant deviation from Hardy-Weinberg equilibrium, while only one locus pair was in linkage disequilibrium after false discovery rate correction for multiple testing (P < 0.05). Cross-species amplification tests revealed that the transferability of 14 loci (70%) was positive for the two congeners M. endeavourae and M. gracilis. The accessibility to new polymorphic microsatellite loci will facilitate population genetic studies and aid in developing conservation and management strategies for vulnerable marine ecosystems.

Bait-attending amphipods of the Tonga Trench and depth-stratified population structure in the scavenging amphipod Hirondellea dubia Dahl, 1959.

BACKGROUND: The hadal zone encompasses the deepest parts of the world's ocean trenches from depths of ∼6,000-11,000 m. The communities observed at these depths are dominated by scavenging amphipods that rapidly intercept and consume carrion as it falls to the deepest parts of the trenches. New samples collected in the Tonga Trench provide an opportunity to compare the amphipod assemblages and the population structure of a dominant species, Hirondellea dubia Dahl, 1959, between trenches and with earlier data presented for the Tonga Trench, and other trenches in the South Pacific. METHODS: Over 3,600 individual scavenging amphipods across 10 species were collected in seven baited traps at two sites; in the Horizon Deep site, the deepest part of the Tonga Trench (10,800 m) and a site directly up-slope at the trench edge (6,250 m). The composition of the bait-attending amphipods is described and a morphometric analysis of H. dubia examines the bathymetric distribution of the different life stages encountered. RESULTS: The amphipod assemblage was more diverse than previously reported, seven species were recorded for the first time from the Tonga Trench. The species diversity was highest at the shallower depth, with H. dubia the only species captured at the deepest site. At the same time, the abundance of amphipods collected at 10,800 m was around sevenfold higher than at the shallower site. H. dubia showed clear ontogenetic vertical structuring, with juveniles dominant at the shallow site and adults dominant at the deep site. The amphipods of the deeper site were always larger at comparable life stage. DISCUSSION: The numbers of species encountered in the Tonga Trench is less than reported from the New Hebrides and Kermadec trenches, and six species encountered are shared across trenches. These findings support the previous suggestion that the fauna of the New Hebrides, Tonga and Kermadec Trenches may represent a single biogeographic province. The ontogenetic shift in H. dubia between the two Tonga Trench sites supports the hypothesis of interspecific competition at the shallower bathymetric range of the species, and the presence of competitive physiological advantages that allow the adults at the trench axis to exploit the more labile organic material that reaches the bottom of the trench.

Rediagnosis of the squat lobster genus Gastroptychus Caullery, 1896, with a new genus Sternostylus and a new family Sternostylidae (Crustacea: Decapoda: Anomura: Chirostyloidea).

The chirostyloidean squat lobster genus Gastroptychus Caullery, 1896 is revised and is split into two genera: Gastroptychus sensu stricto (type species, Ptychogaster spinifer A. Milne-Edwards, 1880) and Sternostylus new genus (type species, Ptychogaster formosus Filhol, 1884). Gastroptychus sensu stricto, is restricted to nine species with a sternal plastron, at sternite 3, abruptly demarcated from the preceding sternites (excavated sternum) by a distinct step forming a well-defined transverse or concave anterior margin at the articulation with maxillipeds 3, the maxillipeds 3 widely separated, with the distal parts accommodated in the excavated sternum between the left and right maxillipeds 3 when folded, and the P2-4 dactyli with the terminal spine demarcated by a suture. Sternostylus new genus, represented by 12 species, has the sternite 3 anteriorly bluntly produced medially and steeply sloping anterodorsally to the anterior sternite, with a pair of spines directly behind the anterior margin, the left and right maxillipeds 3 adjacent, and the P2-4 dactyli ending in an indistinctly demarcated corneous spine. The above-mentioned characters of Gastroptychus are consistent with Chirostylidae sensu stricto. Published molecular phylogenies indicate, however, that Sternostylus is the sister group to all the other Chirostylidae, and is designated the type genus of a new family, Sternostylidae.

Southern high latitude squat lobsters II: description of Uroptychus macquariae sp. nov. from Macquarie Ridge.

Squat lobsters have only recently been recorded from the Macquarie Ridge, which extends south between New Zealand and Antarctica. Among these, Uroptychus insignis (Henderson, 1885) was recorded for the first time outside the western Indian Ocean, exhibiting only subtle morphological differences. Reexamination of the Macquarie Ridge and Indian Ocean specimens attributed to U. insignis using morphological and molecular data revealed the Macquarie Ridge form to represent a separate species. Subtle but consistent morphological differences are evident and partial CO1 sequence data indicates that the specimens collected on Macquarie Ridge differ from those collected in the Indian Ocean by more than 7%. The Macquarie Ridge species is described herein as Uroptychus macquariae n.sp. Subtle morphological differences between the new species and U. insignis are discussed.

Two new species of Munidopsis (Crustacea: Anomura: Munidopsidae) from the Kermadec and Louisville ridge systems off New Zealand.

Two new species of Munidopsis are described from the wider New Zealand region. Munidopsis bamberi sp. nov. is described from the Havre Trough adjacent to the Kermadec Volcanic Arc north-east of the New Zealand continental shelf, and is named in honour of Roger Bamber for his contributions to arthropod taxonomy and systematics. The second species is M. sculpo sp. nov. from Forde Seamount on the Louisville Ridge east of New Zealand. This brings the number of Munidopsis species known in New Zealand waters to 17 and a key to the New Zealand species is provided.