A new species of Austrofilius ( Crustacea , Isopoda , Janiridae ) from the Western Mediterranean *

A new species of the asellote isopod family Janiridae is described from the Mediterranean coast of Spain (Columbretes Islands, Castellón de la Plana): Austrofilius mediterraneus sp.nov. To date, only two species of the genus are known: A. furcatus Hodgson, 1910 and A. serratus Vanhöffen, 1914, both from the waters of the Antarctica. One additional species, A. arnaudi Kussakin and Vasina, 1980 is currently placed as a janirid genus incertae sedis (Wilson and Wägele, 1994). This report is the first record of the genus Austrofilius Hodgson, 1910 in the Northern Hemisphere. The new species is compared with the main features of other species of the genus.

Eastern coast of the Iberian Peninsula (Columbretes and Balearic Islands).In this expedition, 99 sites were sampled with classical methods of trawling and pelagic fishing and by scuba diving.Specimens of Austrofilius were collected on only one occasion: sample 273B1, 12.07.94,by scuba diving.Specimens were fixed in alcohol 70% and examined in glycerine.Drawings were prepared with a stereoscopic microscope Wild M5 and a microscope Olympus CH-2, both equipped with a camera lucida.Type specimens are in the Museo Nacional de Ciencias Naturales, Madrid (MNCN), Repository data: MNCN 20.04/5342a (holotype), MNCN 20.04/5342b (paratypes).
Description: Body depressed, broad, with lengthwidth ratio of 3, dorsally smooth (Fig. 1A).Cephalon (Figs. 1A,B,C ; 5C,D) broader than long, with smooth lateral margins (often serrated: 5 teeth observed in one male paratype).Smooth lateral upper margins of rostrum (often serrated: 4 acute teeth observed in the same male paratype).Rostrum lower margin pointed frontolaterally and medial margin indented.Inconspicuous dorsal eyes, with two ocelli.Pereonites 1-3 acute on frontolateral corners.Pleotelson (Figs. 1A; 5A) broader than long, with rounded lateral margins and apex slightly acute.Margins with many setae; one is particularly robust, directed laterally, near a distolateral small point in the female.
Male antenna 1 (Fig 1D) more slender than in the female.Basal article robust with few small spines (two stout ones in the female), article 2 the longest with two long penicillate setae, article 3 the shortest.Two flagellar articles, first 40% length of second.One aesthetasc and one apical seta.Antenna 2 broken off in material studied.Peduncular article 3 (Fig 1E ) with exopod bearing three setae.
Mandible (Fig 2A) with palp of three articles, the first bearing a single seta.The second is the longest, with two short, stout setae on ventral margin.The third has a ventral row of five setulated setae, the apical being the longest.Pars incisiva of left mandible with 6-7 teeth and lacinia mobilis 3 toothed.Pars molaris cylindrical, indented, with acute protuberances on molar process, and with a dorsal row of 5 setae.
Maxilla 1 (Fig 2B ) with endite bearing about 10 serrated strong setae.Maxilla 2 (Fig. 2C) with about 3 setae at the apex of each lobe, shorter in the inner one, which bears many serrated setae.
A NEW MEDITERRANEAN SPECIES OF AUSTROFILIUS 259 Uropod (Fig. 4E) with sympod bearing about five setae.Endopod longer and broader than exopod, both having simple setae.
Female pleopod 2 (operculum, Fig. 5B) ovate with four distolateral setae and some fine and short hairs on distal margin.
figures, the rostrum of A. furcatus is more extended into two frontolateral tips and the medial margin is more indented than in A. mediterraneus sp.nov.The upper lateral margins of the rostrum of A. mediterraneus sp.nov.may be denticulate in males (but not in the female), like in A. serratus.The male pleopod 1 of A. mediterraneus sp.nov.differs from those of A. furcatus and A. serratus in its shape, being wider at the apex in A. mediterraneus sp.nov.The curved hook-like lateral horns, nearly surpassing the medial lobes, are the main feature that distinguishes the new species from the others.Furthermore, the female operculum of both Antarctic species shows numerous setae on the distal margin.In A. mediter-raneus sp.nov., only four distolateral setae have been observed.
The two Antarctic species are also more setose than the new species, especially on the pereopods.Table 1 compares the features of three species of the genus.1992).The origin of the genus Austrofilius is more probably the Southern margin of the Gondwana continent during the Jurassic or lower Cretaceous (Mesozoic); it presumably expanded throughout Africa and the Northern hemisphere after the South Atlantic opened and joined the North Atlantic during the upper Cretaceous (Maldonado, 1989).This origin also would account for its presence in Antarctica, as in the case of several families of Sphaeromatidea (Serolidae, Bathynatallidae, and Plakarthriidae) and Valvifera (Arcturidae) (Brandt, 1999).
FIG. 5. -Austrofilius mediterraneus sp.nov., male holotype: A2, rigth half of pleotelson; A1, left half of pleotelson of a female paratype; B, operculum of the same female paratype; C, lateral view of cephalon and pereion (partial) of a male paratype; D, lateral view of cephalon and pereion (partial) of another female paratype.Scale bar: 0.1 mm.