Diversity under a magnifier lens: the case of Typhlotanaidae (Crustacea: Tanaidacea) in the N Atlantic.

Research focusing on 'stout-bodied' typhlotanaids collected from several sites around Iceland and adjacent N Atlantic region has resulted in the description of 15 species new to science, as well as the creation of eight new genera. Typhlotanais eximius Hansen, 1913 is redescribed and transferred to a new genus, while Typhlotanais crassus and Peraeospinosus adipatus are transferred to the genus Larsenotanais. The morphological and the molecular data were combined to consolidate and confirm the validity of the results obtained from both approaches. The polyphyletic nature of the Typhlotanaidae and its serious of its taxonomic diversity are emphasized, although molecular analysis reveals that the 'stout-bodied' Typhlotanaidae form monophyletic clade. Depth and temperature are identified as the main environmental parameters determining the distribution of this group of Typhlotanaidae. Several species are clearly associated with the shelf and upper bathyal of Iceland. The Greenland-Iceland-Faroe Ridge is shown to be a distinct zoogeographical barrier for typhlotanaids inhabiting the deeper slope and abyssal regions around Iceland.

Additions to the Tanaidacea (Crustacea: Peracarida) of Rangitâhua, the Kermadec Islands, from the Southwest Pacific Expedition 2017.

Four new species or morphospecies of tanaidaceans, all of small size (c. 1 mm), from the Rangitâhua-Kermadecs component of the Southwest Pacific Expedition 2017 survey are recorded and described: Collettea coralensis n. sp., leptocheliid sp.RK#1, Psalidichelia concinna n. g. n. sp., and Stachyops cf. sebparri. Six had been described or recorded from the earlier Kermadec Biodiscovery Expedition 2011: Aparatanais tetradonta, Chondrochelia acrolophus, Metatanais progenitor, Paradoxapseudes floppae, Tanais sp., and Zeuxo kermadecensis. This brings the number of known tanaid species from the Rangitâhua/Kermadecs group to ten. The records of the Collettea species are notable for the shallow depths from which they were collected, 4-18 m, and the habitats sampled: coral rubble, coral encrusts on rocks, and red algae.

Two new apseudomorphan species (Crustacea: Tanaidacea: Metapseudidae) from Mo'orea Island (Society Islands, French Polynesia) with taxonomic keys.

Previous information on the taxonomy and distribution of the crustacean order Tanaidacea occurring within the widely-dispersed Polynesian Archipelago has been limited to four nominal species, Apseudes rikiteanus Nobili, Apseudes seurati Nobili, Zeuxo seurati (Nobili) and Tanzanapseudes polynesiensis Müller. Based on specimens collected between 2009 and 2011 from coastal waters of Mo'orea Island (Society Islands, French Polynesia), two new metapseudid tanaidaceans, Apseudomorpha drummi and Cryptapseudes mamua, are described. Keys to the identification of species currently placed within the genera Apseudomorpha Gutu and Cryptapseudes Bacescu are provided.

Tanaidacea (Crustacea: Peracarida) from the Southern French Polynesia Expedition, 2014. I. Tanaidomorpha.

Shallow-water and littoral tanaids from the Southern French Polynesia Expedition, 2014 to Rapa Iti, Morane, Taravai and Mangareva, were examined with the tanaidomorphs represented by nine taxa, four of them described as new species within the genera Chondrochelia, Poorea, Triparatanais, and Zeuxoides. A new paratanaid genus is established, Periparatanais n. gen., and Nobili's Tanais seurati is rediscovered and redescribed as a species distinct from the Hawai'ian Zeuxo insularis n. comb. A broad comparison of tanaid faunas across the Polynesian and eastern Indo-Pacific regions based on the Marine Ecosystems of the World (MEOW) classification shows almost no species-level correspondences but several genera within four apseudomorphan and three tanaidomorphan families are consistently present.

Phylogenetic and functional evidence suggests that deep-ocean ecosystems are highly sensitive to environmental change and direct human disturbance.

An understanding of the balance of interspecific competition and the physical environment in structuring organismal communities is crucial because those communities structured primarily by their physical environment typically exhibit greater sensitivity to environmental change than those structured predominantly by competitive interactions. Here, using detailed phylogenetic and functional information, we investigate this question in macrofaunal assemblages from Northwest Atlantic Ocean continental slopes, a high seas region projected to experience substantial environmental change through the current century. We demonstrate assemblages to be both phylogenetically and functionally under-dispersed, and thus conclude that the physical environment, not competition, may dominate in structuring deep-ocean communities. Further, we find temperature and bottom trawling intensity to be among the environmental factors significantly related to assemblage diversity. These results hint that deep-ocean communities are highly sensitive to their physical environment and vulnerable to environmental perturbation, including by direct disturbance through fishing, and indirectly through the changes brought about by climate change.

Marsupial brood care in Cretaceous tanaidaceans.

Parental care in animal evolution has long fascinated biologists, but tracing this complex of behavioural repertoires is challenging, as these transitory states often leave no corporeal traces as fossils. Among modern invertebrates, the tanaidaceans (Malacostraca: Peracarida), a lineage of marsupial crustaceans, show an interesting variety of brooding strategies. Here we report on fossil tanaidaceans from the Cretaceous of Spain and France that provide conclusive evidence for marsupial care of brood-offspring. Two exceptionally preserved female specimens of Alavatanais carabe and A. margulisae from Late Albian Peñacerrada I amber (Spain) possess four pairs of rudimentary oostegites, indicating formation of a marsupium. From Recent data, given the taxonomic distribution of a marsupium of four pairs of oostegites, we hypothesize that this may be plesiomorphic for the Tanaidomorpha. We also report on a peculiar tanaidacean specimen referable to the fossil family Alavatanaidae, Daenerytanais maieuticus gen. et sp. nov., from Early Cenomanian La Buzinie amber (France), preserved with its marsupial pouch and content. Our discoveries provide early evidence of the peracarid reproductive strategy, as seen in modern Tanaidacea, and argue that this form of parental care may have played a role in the diversification of the lineage during this period.

The synonymy of the genus Permixtimella Gutu, 2016 (Crustacea: Tanaidacea) with Ektraleptochelia Bamber & Marshall, 2015 and remarks on other leptocheliid taxa.

Gutu (2016) described a new subfamily, seven new genera and 21 new species in the family Leptocheliidae. However, another five genera and twelve new species, not mentioned by him, were described in 2015 and 2016. Study of the overlooked genera reveals that the morphology of the female of Permixtimella (genus described from both sexes) is similar to those of the type-female of the genus Ektraleptochelia (whose male is unknown). Permixtimella is considered a junior synonym of Ektraleptochelia, which includes two species: E. phoxops and E. oculifurcillata. The place of Ektraleptochelia, Catenarius and Larsmentia within leptocheliid systematics, formerly in the subfamily Catenariinae, is reconsidered and the last genus retained. Some similarities between the females of Nuberis and Bathyleptochelia are presented for the first time. The species Leptochelia acrolophus, L. mexicana, L. ortizi, L. taitungensis and L. grandidentata are transferred to other genera, becoming Chondrochelia acrolophus, C. mexicana, C. ortizi, C. taitungensis and Makassaritanais grandidentatus, respectively. The species Leptochelia pinarensis and L. suhi are considered a junior synonym of Leptochelia forresti and Makassaritanais grandidentatus, respectively.

New deep-sea Paratanaoidea (Crustacea: Peracarida: Tanaidacea) from the northeastern Gulf of Mexico.

One new genus is erected and four new species of paratanaoidean tanaidaceans are described from deep waters in the northeastern Gulf of Mexico: one in each of the genera Collettea, Tanaella, and Pseudomacrinella, and one as a new genus in the family Anarthruridae. Keys to species in the genera Collettea, Tanaella, and the genera of the Anarthruridae are provided.

The first pagurapseudid species (Peracarida: Tanaidacea) from New Zealand with remarks on paguridean (Decapoda: Paguridea) and pagurapseudid convergence and competition.

A new species of pagurapseudid, Macrolabrum maui, is described from the lower eulittoral rocky shore on the East Coast of the North Island, New Zealand. It is similar to M. haikung from Bass Strait, Australia and M. distonyx from New Caledonia. Males and females show little dimorphism. Typical of the subfamily Pagurapseudinae, M. maui inhabits shells of micro-molluscs such as the gastropods Eatoniella, Merelina, and Pisinna. A dichotomous key to the species of Macrolabrum is given. Possible competition for micro-mollusc shells between small pagurideans, notably their glaucothoe stage, and pagurapseudids is considered based on their convergent morphologies and on body sizes.

New littoral, shelf, and bathyal Paratanaidae (Crustacea: Peracarida: Tanaidacea) from New Zealand, with descriptions of three new genera.

Three new genera, Acallocheirus, Aparatanais, and Penteparatanais, and seven new species of the paratanaid subfamily Paratanaidinae are described from New Zealand. New records of three previously known species Atemtanais taikaha, Paratanais paraoa, and P. tara, are also given. Paratanais denticulatus, P. intermedius, P. malignus, P. spinanotandus,and P. vicentetis are transferred to Aparatanais. A key is given to all paratanaidin genera and the NZ Paratanais species. In NZ waters, paratanaids are now known from the littoral zone to 908 m in the bathyal regions of the Chatham Rise and Hikurangi Margin, several of the offshore species being recorded in bryozoan mats. All but one appear to be endemic but may have sibling species elsewhere, particularly in the Southern Hemisphere. Supplementary notes are given on two Australian species P. maleficus and P. perturbatius that clarify their description and diagnostic characters.