Abstract
Most sternaspid species have been described from shallow water, and Caulleryaspis Sendall & Salazar-Vallejo, 2013 includes one deep water species: C. gudmundssoni Sendall & Salazar-Vallejo, 2013 from Iceland. In Sternaspis Otto, 1821, the most speciose genus, most species were described from shallow water and only three thrive in deep water: S. maior Chamberlin, 1919 from the Gulf of California, S. princeps Selenka, 1885 from New Zealand, and S. riestchi Caullery, 1944 from Indonesia. The study of some deep sea sternaspids from the Pacific Ocean in the collections of six research institutions resulted in the discovery of six undescribed species, and for three of them there were abundant materials showing ventro-caudal shield development. Caulleryaspis fauchaldi sp. n. is described based on specimens from Oregon and California; it differs from the known species because it has a shield with rounded anterior margins and its peg chaetae form thin, small spines. Caulleryaspis nuda sp. n. was collected off Oregon; it is unique because its shield lacks a layer of sediment particles firmly attached, but has instead a thin layer of small particles loosely attached. Four other species are newly described in Sternaspis: S. annenkovae sp. n. was collected east off the northern Kurile Islands in about 4,000 m depth; it differs from other species by having a bicolored body, with the introvert darker than the abdomen, and its ventro-caudal shield plates are divergent resulting in a divided fan. The second species, S. maureri sp. n. was found off Peru in 1296–6489 m water depths and in the Southwestern Pacific in 795–3830 m; it resembles S. williamsae sp. n. but differs because its shield has better-developed ribs, the fan has a shallow or indistinct median notch and has lateral notches well-developed. The third species, S. uschakovi sp. n., was found in the Okhotsk Sea in 592–1366 m, off California in 1585 m, Gulf of California in 1200–1274 m, and Western Mexico in 2548 m; it resembles S. africana Augener, 1918 and S. andamanensis Sendall & Salazar-Vallejo, 2013 in having shields with a denticulate posterior margin; the latter two species live in shallow water and they differ from each other and from the new species by a combination of shield and papillae features. The fourth species, S. williamsae sp. n., was found off Oregon in 1000–2400 m, and off California in 878–1246 m; it resembles S. annenkovae because both species have shields with fans narrower than the anterior margin width, but differ in the relative development of shield features and in the relative size of prostomium and mouth; as stated above it also resembles S. maureri sp. n. but its shield has poorly-developed ribs, its median notch is distinct, and the lateral notches are poorly developed or indistinct. Keys to identify all species of Caulleryaspis and Sternaspis are also included.
Highlights
In the polychaete family Sternaspidae Carus, 1863, most species have been described from shallow water, of less than 200 m depth (Sendall and Salazar-Vallejo 2013); one of the two known species of Caulleryaspis Sendall & Salazar-Vallejo, 2013 and only three species in Sternaspis Otto, 1821 were described from deeper water, of around 1000 m depth: S. maior Chamberlin, 1919, S. princeps Selenka, 1885, and S. rietschi Caullery, 1944
The former was described from the Gulf of California, Eastern Pacific Ocean, whereas the two other species were described from specimens collected in the Southwestern Pacific
Deep water sternaspids are delicate, fragile and difficult to study because they are often rare, but some abundant specimens have allowed us to study the development of the ventro-caudal shield
Summary
In the polychaete family Sternaspidae Carus, 1863, most species have been described from shallow water, of less than 200 m depth (Sendall and Salazar-Vallejo 2013); one of the two known species of Caulleryaspis Sendall & Salazar-Vallejo, 2013 and only three species in Sternaspis Otto, 1821 were described from deeper water, of around 1000 m depth: S. maior Chamberlin, 1919, S. princeps Selenka, 1885, and S. rietschi Caullery, 1944. Six new deep-water sternaspid species (Annelida, Sternaspidae) from the Pacific Ocean 11 brick red or dirty orange, ribs and concentric lines are always visible but variably developed; anterior margins are rounded to barely acute (Fig. 4E–G); fan markedly notched, margin barely crenulated to markedly crenulated, barely projected beyond the posterior corners.
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