Biology and life cycle of Tmetonyx similis (G. O. Sars, 1891) (Amphipoda,Lysianassidae), a scavenging amphipod from the continental slope of the Mediterranean

The present study focused on the biology and life cycle of Tmetonyx similis, a scavenging amphipod inhabiting the continental slope of the north‐western Mediterranean. All the categories of individuals were observed in the samples. The emergence of offspring occurs in successive cohorts. The lifespan of the females is longer than that of the males, but the sex ratio is strongly in favour of the males. The fecundity was found to be lower than that of the other female crustaceans present in these samples. The growth pattern was modelled. A strong correlation was observed between the length and the weight of the animals collected. Several hypotheses are proposed to explain a sex ratio in favour of males. This result may be explained by a migratory process of the females of T. similis. A comparison of the reproduction strategy is given for the three main scavenger crustacean species (amphipods and isopod) collected in this area.     

Biology and life cycle of Scopelocheirus hopei (A. Costa, 1851), a scavenging amphipod from the continental slope of the Mediterranean

The biology of Scopelocheirus hopei, a deep-sea (500 m) scavenging amphipod that lives on the continental slope of Mediterranean canyons, was studied. Animals were collected using a baited trap. A new method was developed for reproducibly measuring the exact length of the animals. All the categories of individuals were always present in the samples. The emergence of offspring occurs in successive cohorts. Individuals of the two sexes do not grow at the same rate: the males grow more quickly than the females, but their lifespans are shorter. The males are always less numerous than the females. Two production cycles occur. The females produce offspring all year round. The mean fecundity was found to be 218 eggs per female. The growth pattern was modelled. A strong correlation was observed between the length and the weight of the animals collected. Several hypotheses are proposed to explain the results obtained.     

Phorbas posidoni n.sp. (Porifera: Poecilosclerida) from the Aegean Sea,with a discussion of the family Anchinoidae

A new species of the genus Phorbas Duchassaing and Michelotti, 1864 (junior synonym Anchinoe Gray, 1867) is described from the Aegean Sea (Eastern Mediterranean). Phorbas posidoni n.sp. is distinguished from the known Mediterranean species of Phorbas primarily by its elaborate repent-ramose habit combined with an extensive, spongin-enforced, plumoreticulate skeleton of oxea-like tornotes and the usual echinating acanthostyles and arcuate chelae. As in most Phorbas the surface bears characteristic areolae. The only other elaborate Mediterranean species, P. mercator (Schmidt) differs clearly in spiculation, since it lacks microscleres and has strongyles as the main skeletal elements. Phorbas fictitius (Bowerbank), P. tenacior (Topsent) and P. paupertas sensu Topsent are all incrusting and differ in spicule form and sizes as well. Likewise, Phorbas species from the neighbouring East Atlantic each show clear differences with P. posidoni n.sp. The genus Phorbas is discussed and compared with Pronax Gray (1867) sensu Lévi (1973). It is proposed to unite the two genera because the alleged sharp difference between the two (only oxea-like tornotes in the skeletal tracts in Phorbas, only acanthostyles in the skeletal tracts in Pronax) is compromised by a range of intermediate conditions in various species.     

Deep-living demersal fishes in the Catalan Sea (western Mediterranean) below a depth of 1000 m

An extensive survey of the deep-living fishes of the Catalan Sea (western Mediterranean) recorded 31 species in 19 families and 29 genera from 100 samples at depths between 960 and 2251 m. Chlorophthalmidae, Moridae and Macrouridae accounted for nearly 85% of all specimens taken. In biomass terms, Hexanchidae, Moridae, Alepocephalidae and Chlorophthalmidae were the most important families. A quantitative model of the bathymetric distribution of the species is presented. The ‘centre of gravity’ of species’ distribution and the habitat width, a measure of the distribution heterogeneity, are also given. Out of the 31 demersal species caught, the distributions of only 13 are centered below 1000 m. The Mediterranean deep-sea ichthyofauna is very impoverished in comparison with the adjacent Atlantic Basin fauna.     

Sillago suezensis,a new whiting from the northern Red Sea,and status of Sillago erythraea Cuvier (Teleostei: Sillaginidae)

The status of Sillago erythraea Cuvier in Cuvier and Valenciennes 1829 is re-examined. A lectotype designation by McKay in 1985 fixes it as a junior synonym of Sillago sihama (Forsskål in Niebuhr, 1775), which is restricted to the southern Red Sea. Northern Red Sea populations previously assigned to S. sihama or S. erythraea, are here described as Sillago suezensis sp. nov. Sillago suezensis is also distributed in the eastern Mediterranean Sea due to Lessepsian immigration through the Suez Canal. The new species is characterized within the Sillago sihama group, which has the swimbladder divided posteriorly into two tapering extensions projecting below the vertebral column extending into the tail musculature, by the absence of scales on the preopercle and on most of the opercle, a total number of 34 vertebrae, the swimbladder with lateral extensions each spreading a blind tubule anterolaterally, and a low position of the nostril.

http://www.zoobank.org/urn:lsid:zoobank.org:act:B289CDF4-AE82-44D3-9AE1-4A2B514AD348     

Two new species of asterocherid (Copepoda: Siphonostomatoida) associated with a sponge from the Strait of Messina,Italy: taxonomic and ecological traits

Two new species of asterocherid associated with sponges are described from the Mediterranean Sea. They are Psilomyzon laetitiae sp. nov. and Psilomyzon sarcotragusicola sp. nov. The genus Psilomyzon consists of only one known species, P. pauciseta. The two new species can be easily distinguished from the cogener species by reduction of the endopod of leg 4. In P. pauciseta the leg 4 endopod is 3-segmented, with the third segment reduced; in both new species it is 2-segmented, with the second segment carrying an inner projection, possibly homologous to the third segment of the leg 4 endopod of P. pauciseta. In the two new species, the bifid outer process on male leg 4 second endopodal segment seems to be serially homologous to the similar processes on the same segment in legs 1–3, whereas the inner projection may represent a vestigial element of the third endopodal segment of leg 4.

http://zoobank.org/urn:lsid:zoobank.org:pub:33BF0653-BBA9-426B-B365-5D8C62DFD44A     

Alien polychaete species (Annelida: Polychaeta) on the southern coast of Turkey (Levantine Sea,eastern Mediterranean), with 13 new records for the Mediterranean Sea

The examination of benthic material collected from different depths and habitats along the southern coast of Turkey (Levantine Sea, eastern Mediterranean) in September and October 2005 revealed 30 alien polychaete species belonging to 15 families. Thirteen species (Pisione guanche, Linopherus canariensis, Onuphis eremita oculata, Lumbrineris perkinsi, Dorvillea similis, Timarete caribous, Pherusa parmata, Pherusa saldanha, Streblosoma comatus, Polycirrus twisti, Laonome triangularis, Branchiomma bairdi and Janua steueri) are new to the Mediterranean fauna, 24 species are new to the Turkish fauna and 27 species are new to the Levantine coast of Turkey. The specimens collected from the Levantine coast of Turkey and northern Cyprus that were previously identified as Linopherus acarunculata and Branchiomma boholense are reidentified as L. canariensis and B. bairdi, respectively. In the light of present knowledge, the previous reports of Lumbrineris inflata and Streblosoma hesslei from the Mediterranean (Italian coast) could refer to the species L. perkinsi and S. comatus, respectively. The species new to the Mediterranean Sea are redescribed and discussed.     

Redescription of Retilaskeya horrida (di Monterosato, 1874) comb. nov. and a re-evaluation of the taxonomic affinity of the genus Retilaskeya (Caenogastropoda: Triphoroidea)

The family Cerithiopsidae H. Adams and A. Adams, 1853 is distributed worldwide, and comprises around 800 extant species divided into ~40 genera. The most speciose genus within the family is Cerithiopsis Forbes and Hanley, 1850, a taxon currently used as a general receptacle rather than as a proper phylogenetic lineage. We hereby redescribe the rare species Cerithiopsis horrida di Monterosato, 1874, review its nomenclature, known material, and distribution as well as figure the entire protoconch, operculum, and radula for the first time. Our results highlight extreme differences between ‘Cerithiopsis’ horrida and the Cerithiopsis type species Cerithiopsis tubercularis (Montagu, 1803) and strong morphological and radular similarities with species belonging to the genus Retilaskeya Marshall, 1978. A wide discussion lists several taxa that might be ascribed to the same group of species, which presumably constitute a different worldwide lineage. Pending relevant molecular phylogenetic studies of the Triphoroidea Gray, 1847, for morphological conformity we suggest transferring ‘Cerithiopsis’ horrida to the genus Retilaskeya, and the same action is presumably appropriate for its possible sister species ‘Cerithiopsis’ leopardus Rolán and Gori, 2013. Finally, Retilaskeya better conforms to Newtoniellidae Korobkov, 1955 than Cerithiopsidae.     

Minute but constant morphological differences within members of Stenothoidae: the Stenothoe gallensis group with four new members,keys to Stenothoe worldwide,a new species of Parametopa and Sudanea n. gen. (Crustacea: Amphipoda)

The hitherto-known species of Stenothoe are grouped by their distribution. A key for Mediterranean–Atlantic species is given. To the so-called Stenothoe gallensis group (until now, four species), four others are added: S. andamanensis, S. clavetta, S. himyara and S. senegalensis, all new to science. Knowledge of Stenothoe aucklandica, frecanda, macrophthalma, valida and verrucosa is amended. The studied material also yields both a new species of Parametopa (P. gorea n. sp.) and a new genus (Sudanea n. gen.) with S. inopinata n. sp.

http://zoobank.org/urn:lsid:zoobank.org:pub:23C8BB82-5CC1-40B2-BED9-431AA55901B9     

A new species of Hyalella from Colombia,and the redescription of H. meinerti Stebbing, 1899 from Venezuela (Crustacea: Amphipoda)

The new species H. quindioensis is described from Colombia. This species is close to H. paramoensis Andres, 1988 also in Colombia. Hyalella meinerti Stebbing, 1899 is figured and redescribed. The type locality for this species is Venezuela. However, it has a wide distribution including Colombia, Peru, Ecuador and Brazil.     

On Liljeborgia fissicornis (M. Sars, 1858) and three related new species from Scandinavia,with a hypothesis on the origin of the group fissicornis

The large and common Scandinavian amphipod Liljeborgia fissicornis (M. Sars) is split into four species: the deep-water L. caliginis sp. nov. and L. charybdis sp. nov., and the shallow-water L. fissicornis and L. ossiani sp. nov. The poorly known species L. polosi Barnard and Karaman, recorded from the deep Canadian Basin of the Arctic Ocean, is considered as belonging to the same group. All those northern species are completely devoid of eyes, while similar species from the Antarctic and sub-Antarctic continental shelf do have eyes. It is hypothesized that the group fissicornis, which is specific to cold waters, derives from ancestors living on the continental shelf of the Southern Ocean. These ancestors would have adapted to deep-sea environments, losing their eyes completely. Then they would have migrated northwards through the cold abyss, and reached the cold but shallow waters of the Arctic/sub-Arctic continental shelf, without redeveloping visual organs.     

Species of Symplectoscyphus Marktanner-Turneretscher, 1890 (Cnidaria: Hydrozoa,Sertulariidae) from recent Antarctic expeditions with R.V. Polarstern,with the description of four new species

Fifteen species of the genus Symplectoscyphus Marktanner-Turneretscher have been studied, four of which are new to science (Symplectoscyphus anae sp. nov., S. frigidus sp. nov., S. sofiae sp. nov. and S. weddelli sp. nov.). The material studied originates from the Weddell Sea and was collected by several French and German Antarctic expeditions with R.V. Polarstern. Each species is described and figured, the systematic position amongst allied species discussed and available data concerning autecology and geographical distribution given. The type material of five poorly known species of Symplectoscyphus, S. aggregatus (Jäderholm), S. cumberlandicus (Jäderholm), S. glacialis (Jäderholm), S. hero Blanco and S. plectilis (Hickson and Gravely), has been re-examined, re-described and figured. Finally, a general survey of the bathymetrical and biogeographical distribution of the known Antarctic species is given.     

Distribution and characterization of species of Gyrodactylus Nordmann, 1832 (Monogenea) parasitizing salmonids in the UK,and their discrimination from G. salaris Malmberg, 1957

The reported pathogenicity of the monogenean Gyrodactylus salaris Malmberg, 1957 on Atlantic Salmo salar in Norway has necessitated a national survey of salmonid sites throughout the British Isles to determine which species of the genus Gyrodactylus are resident on these hosts in British waters. Eight morphotypes were identified following examination of the opisthaptoral sclerites at both the light and scanning electron microscope level. Gyrodactylus truttae Gläser, 1974 was found on wild brown trout Salmo trutta in Scotland, England and Wales with an uncharacteristic morphotype, having long, thin marginal hooks. Two morphotypes of Gyrodactylus derjavini Mikailov, 1975 were recorded for the first time from Britain. G. caledoniensis n. sp. from Scottish S. salar is erected, based on differences in the shape and size of the marginal hooks. Two possible new species from English Salvelinus alpinus and a possible new species from Welsh S. salar and Scottish O. mykiss are described.     

Larval development and emigration behaviour during sea-to-land transition of the land hermit crab Coenobita brevimanus Dana, 1852 (Crustacea: Decapoda: Anomura: Coenobitidae) under laboratory conditions

To determine the early life history of the land hermit crab Coenobita brevimanus Dana, 1852, larvae were cultured individually in the laboratory. The zoeal and the megalopal stages are described and illustrated. The larvae developed through four planktonic zoeal stages to the megalopal stage. The major differences in the zoeal characters between C. brevimanus and other described Coenobita species were found in the armature of the pleomeres, whereas the character of pleomeres of C. brevimanus zoeae is the same as that of the coconut crab Birgus latro, a different genus in the same family. Morphological similarity was also found in segmentations of antennules and antennae in megalopae between C. brevimanus and the coconut crab. Megalopae of C. brevimanus were cultured in containers holding seawater and a hard substrate. These crabs migrate from the sea to land after developing a habit of acquiring gastropod shells.