Scyllarus arctus

(Linnaeus, 1758)

Diagnosis:
Carapace with 3 distinct acute teeth in the median line before the cervical groove (the gastric pregastric and rostral teeth). Region between the postrostral and branchial carinae with only a few tubercles, and with extensive smooth areas. Abdomen without a sharp median ridge, but each of somites 2 to 5 with an elongate lobulate figure in the middle. The exposed part of somites 2 to 5 with an arborescent arrangement of very narrow grooves. Somite 1 with a complete transverse groove, behind which there are numerous short longitudinal grooves that are rather irregular in shape, may divide and sometimes are interconnected by transverse grooves; this posterior half of somite 1 of equal length throughout its width, not longer in the middle that at the sides. The smooth anterior half of abdominal somites 2 to 6 (i.e., the part of the somite that disappears under the previous somite when the abdomen is fully stretched) without any indication of grooves or rows of hairs. Fourth segment of antenna with a single oblique median carina. Outer margin of the segment with 2 teeth, the inner margin with 3 or 4 (not including the apical tooth). Thoracic sternum anteriorly V-shapedly incised in the middle. A blunt and low median tubercle on the last thoracic sternite; this tubercle somewhat flattened posteriorly, not conical as in S. pygmaeus. Dactyli of legs without fringes of hair.
Colour: reddish brown with a dark brown pubescence. A dark brown, not sharply delimited spot in the central part of abdominal somite 1. Segments of the pereiopods with a dark blue band each.

Type:
Type locality of Cancer Arctus and Arctus ursus (the latter is a replacement name for the former): " Habitat in M [ari]. Europae, Asiae, Africae, Americae". As lectotype of the species is now selected the specimen figured by Barrelier (1714: 131, fig. 1288 II) as "Squilla Ursa minor altera remipes", the only specimen of the present species cited by Linnaeus (1758). Barrelier's specimen was collected and figured by him during his travels in "Galliam, Hispaniam et Italiam", no exact locality is given, but the type locality may be arbitrarily restricted to Ostia, the port of Rome, as in the second page of Barrelier's biography in the introduction to his 1714 book, it is said that in Ostia he figured marine insects (= Crustacea): "Portum Ostiensem... Plantas investigandi causâ perlustravit, Marinasque plurimas, Insecta simul and Conchylia depinxit". On p. xxvi of the chapter "Index Iconum Barrelieri" of his book, all the Crustacea Mollusca and Echinodermata that he figured are listed as "Insecta marina". The lectotype is almost certainly no longer extant, but the figure is so exact that there cannot be any doubt as to the identity of the specimen.
Type locality of Cancer (Astacus) ursus minor: "Man findet diesen Krebs im Mittelländischem Meere". Type material in ZMB, no longer extant.
Type locality of Scyllarus tridentatus: "Its habitat is unknown". The specimen was observed by Leach "in the collection of William Comyns, Esq. of Mount Pleasant, near Dawlish, Devonshire" and thus may have come from the south coast of England. Whereabouts of the type material unknown.
Type locality of Scyllarus cicada: "Environs de Nice", "dans les rochers du litoral". Depository of type material unknown.
Type locality of Chrysoma mediterraneum: "dans nos mers [= seas near Nice, dépt. Alpes Maritimes, S. France]. Depository of types unknown.
Type locality of Phyllosoma sarniense: "on the Coast of Guernsey", Channel Islands, Great Britain. Depository of type unknown.
Type locality of Phyllosoma parthenopaeum: "Trovato a galleggiare nella marina di Capri", near Naples, Italy. Depository of larval holotype unknown.
Type locality of both Nisto laevis and Nisto asper: "Les deux Nisto ont été decouverts... dans les eaux de Saint-Jean, près de Nice", dépt Alpes Maritimes, S. France. Depository of syntypes of either species unknown.
Type locality of Arctus crenulatus: "Porto-Santo (Madère)", later (Bouvier, 1905:2) given more detailed as "de la baie de Porto-Santo..- par 100 mètres de profondeur". Holotype in MOM.
Type locality of Scyllarus arctus lutea: Nice, S. France. Depository of type unknown.
Type locality of Yalomus depressus: "in the Sicilian Seas", Italy. Types lost.

Diagnostic Features:
Carapace with 3 distinct acute teeth in the median line before the cervical groove (the gastric pregastric and rostral teeth). Region between the postrostral and branchial carinae with only a few tubercles, and with extensive smooth areas. Abdomen without a sharp median ridge, but each of somites 2 to 5 with an elongate lobulate figure in the middle. The exposed part of somites 2 to 5 with an arborescent arrangement of very narrow grooves. Somite 1 with a complete transverse groove, behind which there are numerous short longitudinal grooves that are rather irregular in shape, may divide and sometimes are interconnected by transverse grooves; this posterior half of somite 1 of equal length throughout its width, not longer in the middle that at the sides. The smooth anterior half of abdominal somites 2 to 6 (i.e., the part of the somite that disappears under the previous somite when the abdomen is fully stretched) without any indication of grooves or rows of hairs. Fourth segment of antenna with a single oblique median carina. Outer margin of the segment with 2 teeth, the inner margin with 3 or 4 (not including the apical tooth). Thoracic sternum anteriorly V-shapedly incised in the middle. A blunt and low median tubercle on the last thoracic sternite; this tubercle somewhat flattened posteriorly, not conical as in S. pygmaeus. Dactyli of legs without fringes of hair. Colour: reddish brown with a dark brown pubescence. A dark brown, not sharply delimited spot in the central part of abdominal somite 1. Segments of the pereiopods with a dark blue band each.

Geographical Distribution:
Eastern Atlantic region from the south coast of the British Islands to the Azores, Madeira and the Canary Islands, as well as the entire Mediterranean.

Habitat and Biology:
Depth range from 4 to 50 m; on rocky or muddy substrates, and also in Posidonia prairies. Ovigerous females from February to April.

Size:
Total body length usually between 5 and 10 cm, maximum body length about 16 cm.

Interest to Fisheries:
Minor. The species is edible and used as food, but there is no special fishery for it, being usually taken as a by-catch in other fisheries. It has been taken with gill nets, trawls, dredges, traps and seines. It is also taken by hand by divers, who at places seem to have decimated the populations, especially after the introduction of Scuba gear. The animals are offered for sale at local markets, usually fresh. The relatively small size and the fact that it is never abundant make the species economically not very attractive.

Remarks:
The name "Phyllosoma sarniense" is not mentioned in Lukis' (1835: 459-464) article, the editor even put in this article on p. 462 a bracketed remark" "Will Mr Lukis please to take an early opportunity of adding a specific epithet". The name is provided in the index to the volume (8) of The Magazine of Natural History in which Lukis' article appeared; on p. 685 of the index is cited "Phyllosòma sarniénse Lukis, and other species, 461".

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