ABSTRACT
Thirty-seven holothuroid species, including six potentially new, are reported from the eastern Weddell Sea in Antarctica. Information regarding sea cucumbers in this dataset is based on Agassiz Trawl (AGT) samples collected during the British Antarctic Survey cruise JR275 on the RRS James Clark Ross in the austral summer of 2012. Species presence by site and an appendix of holothuroid identifications with registrations are included as supplementary material. Species occurrence in the Weddell Sea is updated to include new holothuroids from this expedition.
ABSTRACT
The case put by Alexei Smirnov in 2012 is accepted and the order name Synaptida Cuénot is adopted in place of Apodida Brandt. Two new Synaptida species are described for the Weddell Sea in Antarctica with single author O'Loughlin: Sigmodota magdarogera sp. nov. and Taeniogyrus bamberi sp. nov.. A specimen of Sigmodota magnibacula (Massin & Hétérier) is described. A key is provided for the genera and species of Taeniogyrinae that occur south of the Antarctic Convergence.
Subject(s)
Sea Cucumbers/classification , Animal Distribution , Animal Structures/anatomy & histology , Animal Structures/growth & development , Animals , Antarctic Regions , Body Size , Oceans and Seas , Organ Size , Sea Cucumbers/anatomy & histology , Sea Cucumbers/growth & developmentABSTRACT
The case put by Alexey Smirnov in 2012 is accepted and the order name Synaptida Cuénot is adopted in place of Apodida Brandt. Two new Myriotrochidae Théel species from the continental slope of Australia are described: Prototrochus robbinsae sp. nov. and Prototrochus roniae sp. nov. A key to the six Australasian species of Prototrochus Beljaev & Mironov and a distribution and depth map are provided.
Subject(s)
Sea Cucumbers/classification , Animal Distribution , Animal Structures/anatomy & histology , Animal Structures/growth & development , Animals , Australia , Body Size , Organ Size , Sea Cucumbers/anatomy & histology , Sea Cucumbers/growth & developmentABSTRACT
A new fissiparous asterinid seastar Aquilonastra chantalae sp. nov. is described from Europa Island, one of the Scattered Islands (Les îles Éparses) in the Mozambique Channel. It is compared with the fissiparous asterinid Aquilonastra conandae O'Loughlin & Rowe from the Mascarene Islands. A table of distinguishing diagnostic characters is provided. The asterinid Aquilonastra richmondi O'Loughlin & Rowe is reported for Europa Island.
Subject(s)
Starfish/anatomy & histology , Starfish/classification , Animals , Indian Ocean IslandsABSTRACT
The gastric-brooding asterinid sea star, Smilasterias multipara, broods from late August to early November in the shallow sublittoral zone of southeastern Australia. We observed males and females spawning in the laboratory. They shed gametes through gonopores on the sides of the arms. The eggs were orange, about 1.0 mm in diameter, and heavier than seawater. They were externally fertilized by sperm, and placed into the stomach of the female by the tube feet. Twenty-four hours after fertilization, the first cleavage occurred. Cleavage was equal, total, and radial. Development via a non-feeding lecithotrophic brachiolaria was direct, there being no planktrotrophic bipinnaria or brachiolaria larva. Embryos developed, through wrinkled blastula and gastrula stages, into brachiolariae with arms. All of the surfaces of the brachiolaria were covered by cilia. At metamorphosis, a starfish rudiment appeared on the posterior portion of the larval body, while the anterior portion of the larval body was absorbed. Two months after fertilization, metamorphosis was complete. After metamorphosis, juveniles in the stomach grew six pairs of tube feet in each arm. Juveniles, 3 mm in diameter, emerged from the mouth of the mother in early November. Developmental evidence suggests that this asteroid has evolved mechanisms for the protection of larvae and juveniles from gastric digestion.
Subject(s)
Metamorphosis, Biological , Morphogenesis/physiology , Starfish/embryology , Starfish/growth & development , Animals , Australia , Female , Male , Species Specificity , Starfish/physiologyABSTRACT
DNA sequencing (cytochrome oxidase I; 82 sequences; 25 locations) of a species complex of Australian six-rayed sea-stars (genus Patiriella) reveals four well-supported mtDNA clades, corresponding to P. oriens, P. occidens, P. medius, and P. gunnii. These clades have non-random geographic distributions along an east to west axis that are broadly consistent with the biogeographic provinces of southern Australia proposed by. The taxa are deeply divergent (minimum 7.5%) and are estimated to have originated during the late Pliocene. By contrast, intra-clade divergences are small, typically less than 1.0%. Phylogenetic analysis of mtDNA provides strong support for the combined monophyly of multicoloured forms (P. oriens, P. occidens, and P. medius; 100% bootstrap support) and suggests that P. medius (central) and P. occidens (western) may be sister taxa (up to 76% bootstrap support). Maximum likelihood analysis of nuclear DNA sequences (actin; 1437 bp) yields an optimal tree largely consistent with mtDNA groupings, but with little bootstrap support. The biogeographic distribution of P. oriens (eastern) and P. occidens (western) is roughly consistent with a vicariant model involving allopatric divergence during glaciation. In addition, we propose that the Great Australian Bight may also have retained isolated populations during glacial periods, perhaps explaining the "central" distributions of P. gunnii and P. medius.
