Sternaspis Otto, 1821, restricted

Sendall, Kelly & Salazar-Vallejo, Sergio I., 2013, Revision of Sternaspis Otto, 1821 (Polychaeta, Sternaspidae), ZooKeys 286, pp. 1-74 : 16-18

Genus Sternaspis Otto, 1821, restricted

Type species.

Sternaspis thalassemoides Otto, 1821, by monotypy.

Diagnosis.

Sternaspids with introvert hooks falcate, tapered. Pre-shield region with 7 segments. Ventro-caudal shield stiff, usually with radial ribs and concentric lines. Branchial filaments arranged in discrete branchial plates.

Remarks.

A species resembling current Sternaspis was described and illustrated by Janus Plancus in 1760 as a sea cucumber under the name Mentula Cucurbitacea Marina in a book on Mediterranean marine animals ( Plancus 1760). In that account Plancus indicated that the specimen was from near Rimini, the Emilia-Romagna Italian region bordering the Adriatic Sea. From the description and accompanying illustration, he was undoubtedly describing a sternaspid. Plancus apparently neglected to use binomial nomenclature in his work and so his name is not available ( Petersen 2000).

The next described species in the group was Echinorhynchus scutatus Renier (1807). Petersen (2000) indicated that Renier’s paper, or what could be found of it, was rejected as a formal publication by the International Commission of Zoological Nomenclature ( ICZN 1954), although some names have been officialy validated ( Muir and Petersen 2010). Ten years after the account by Renier, the first valid description of a species was published by Ranzani (1817) as Thalassema scutatus .

Otto (1821) proposed Sternaspis to replace Thalassema Ranzani, 1817, and described Sternaspis thalassemoides , which he regarded as closely allied to Thalassema scutatus . Otto indicated that Thalassema had been already employed by Pallas (and replaced by Leach 1816, to Thalessema ). The type species for Sternaspis has been regarded as Echinorhynchus scutatus Renier, 1807 by Hartman (1959), Fauchald (1977) and Gilbert (1984). This is incorrect because of the rejection of the publications by Renier, and because the only species included in the proposal of the new genus was Sternaspis thalassemoides Otto, 1821. Consequently, this must be regarded as the type species by monotypy. Although Ranzani had understood correctly the body ends, Otto confused them because he thought the shield was anterior. Claparède (1869) praised Krohn (1842) and Müller ( Mueller 1852) for setting it straight as to which end of sternaspids was anterior and which posterior. However, it seems that the first indication of the correct body polarity was made by de Blainville (1828: 500-501, Pl. 26, unnumb.), because he corrected the illustrations, although he repeated the confusions regarding the body features.

Sternaspis differs from Petersenaspis gen. n. because the ventro-caudal shield is stiff, the introvert hooks are tapered, not subdistally expanded, and the branchial filaments are arranged in discrete plates, not loosely arranged. Sternaspis differs from Caulleryaspis gen. n. because the latter has a soft ventro-caudal shield with abundant sediment particles on it.

Sternaspis includes, besides the type species, Sternaspis thalassemoides Otto, 1821 reinstated, from the Mediterranean Sea, Sternaspis affinis Stimpson, 1864 from the Northeastern Pacific, Sternaspis africana Augener, 1918, new status, from Western Africa, Sternaspis andamanensis sp. n. from the Andaman Sea, Sternaspis costata Marenzeller, 1879 from Japan, Sternaspis fossor Stimpson, 1853 from the Northwestern Atlantic, Sternaspis islandica Malmgren, 1867 from Iceland, Sternaspis maior Chamberlin, 1919 from the Gulf of California, Sternaspis princeps Selenka, 1885 from New Zealand, Sternaspis rietschi Caullery, 1944 from abyssal depths around Indonesia, Sternaspis scutata (Ranzani, 1817) from the Mediterranean Sea, Sternaspis spinosa Sluiter, 1882 from Indonesia, and Sternaspis thorsoni sp. n. from the Arabian Gulf. In Petersenaspis gen. n., besides the type species, Petersenaspis capillata (Nonato, 1966) comb. n. from Central and Southern Brazil, the genus also includes Petersenaspis palpallatoci sp. n. from the Philippine Islands. Caulleryaspis gen. n. includes Caulleryaspis gudmundssoni sp. n. from Iceland and Caulleryaspis laevis (Caullery, 1944) comb. n. from Indonesia.

Key to species of Sternaspis Otto, 1821

(distribution in parenthesis after studied materials)