Scyllarus Pygmaeus

''Scyllarus pygmaeus'' is a species of slipper lobster that lives in shallow water in the Mediterranean Sea and eastern Atlantic Ocean. It grows to a length of , which is too small for it to be fished for. The juvenile form was first described in 1885, with the description of the adult following in 1888 as a result of the ''Challenger'' expedition.

Description

''S. pygmaeus'' is the smallest slipper lobster species, with a carapace length of for females, and for males. The total body length can reach , but is typically less than . Its small size precludes ''S. pygmaeus'' from being a target for fisheries. The body of ''S. pygmaeus'' is "pale brownish or pinkish with patches of darker hairs".

''S. pygmaeus'' resembles a young individual of '' Scyllarus arctus'', with which it occurs in sympatry. The two species can be distinguished by a suite of characters:
*The anterior part of the abdominal tergites have a groove lined with hairs in ''S. pygmaeus'' but not in ''S. arctus''.
*''S. arctus'' has a forward-pointing, pointed tip to the second abdominal sternites, while in ''S. pygmaeus'' it is rounded and points backwards.
*''S. pygmaeus'' has a conical tubercle on the fifth thoracic somite, while the tubercle is compressed rather than conical in ''S. arctus''.
*The sculptured posterior part of the first abdominal somite is wider in the centre than at the edges in ''S. pygmaeus'', while in ''S. arctus'' it is an even width throughout.

Distribution and ecology

''Scyllarus pygmaeus'' has a wide distribution in the Mediterranean Sea and islands in the eastern Atlantic Ocean, including Madeira, the Canary Islands and the Cape Verde Islands. It has not been observed off the coast of North Africa further east than Morocco. It lives at depths of , where it is nocturnal and at its shallower ranges lives in '' Posidonia'' meadows. Females carry eggs in June and August.

Taxonomic history

''Scyllarus pygmaeus'' was first described in 1888 by Charles Spence Bate as part of the results of the ''Challenger'' expedition. He based his description of "''Arctus pygmaeus''" on material from "off Gomera" in the Canary Islands. In the same publication, he also described "''Arctus immaturus''" from the Cape Verde archipelago, which Eugène Louis Bouvier realised in 1915 was simply the "nisto" (juvenile) stage of ''S. pygmaeus''. Applying the principle of first reviser, Bouvier established that ''S. pygmaeus'' would be the valid name, over ''S. immaturus''. Although ''S. pygmaeus'' is not rare in the Mediterranean Sea, its presence there was overlooked for decades, due to the confusion between it and the more conspicuous ''S. arctus'', whose immature form ''S. pygmaeus'' was often assumed to be. In 1960, Jacques Forest and Lipke Holthuis demonstrated for the first time that ''S. pygmaeus'' does indeed occur in the Mediterranean Sea, from museum specimens at the ' in Naples.

The juvenile "nisto" form of ''S. pygmaeus'' was named earlier than the adult form; Sarado described it in 1885 under the name ''Nisto laevis'' in his 1885 work ' ("Study of the crustaceans of Nice").

The English vernacular name preferred by the Food and Agriculture Organization is ''pygmy locust lobster'', alongside the French ' and the Spanish '.

References

{{Taxonbar, from=Q5415350

Achelata
Crustaceans of the Atlantic Ocean
Crustaceans described in 1888