Soteriscus laouensis, Taiti & Rossano, 2015

Taiti, Stefano & Rossano, Claudia, 2015, Terrestrial isopods from the Oued Laou basin, north-eastern Morocco (Crustacea: Oniscidea), with descriptions of two new genera and seven new species, Journal of Natural History 49 (33), pp. 2067-2138 : 2103-2107

Soteriscus laouensis sp. nov.

( Figures 21 and 22 )

Material examined

Holotype: ♂, St. 16, along road margin under stones, leg. S. Taiti, 28 April 2004 ( MZUF 9509 ) . Paratypes: 1 ♂♂, 35 ♀♀, same data as holotype ( MZUF 9509 ) .

Description

Maximum length: ♂, 13 mm; ♀, 16 mm. Body enlarged, outline as in Figure 21A . Colour: male brown-grey with the usual yellowish muscle spots; female light brown with a marbled pattern, two darker spots per side on the anterior part of pereonites; antennae uniformly grey; pereopods pale with numerous dark spots; pleopodal exopods dark. Back smooth with some scattered short triangular scalesetae ( Figure 21B ); a distinct sulcus marginalis on lateral margins of pereon epimera with numerous gland pores along its whole length ( Figure 21G ); numerous gland pores scattered on the whole dorsal surface of the body; noduli laterales clearly visible, inserted more or less at the same distance from the lateral margin of the pereonites, b/c and d/c co-ordinates as in Figure 21C . Cephalon ( Figure 21D–F ) with no suprantennal line, frontal line straight; very small lateral lobes bent downwards and not protruding frontwards; eye with about 26 ommatidia. Pereonites 1–3 with posterior margin regularly convex; pereonite 4 with posterior margin straight; pereonites 5–6 with posterior corners pointing backwards, pereonite 7 with acute posterior corners and slightly sinuous posterior margin at sides. Pleonites 3–5 with well-developed falciform posterior points ( Figure 21H ). Telson triangular with distinctly concave sides ( Figure 21H ). Antennule ( Figure 21I ) with first article longer than second and third; third article with a short triangular point and a tuft of elongated aesthetascs at apex. Antenna ( Figure 21J ) reaching back posterior margin of pereonite 3; fifth article of peduncle almost as long as flagellum; first flagellar article about 1.5 longer than second. Buccal pieces as in the preceding species. Pleopodal exopods 1 and 2 with monospiracular covered lungs. Uropod ( Figure 21K ) with a triangular depression on protopodal outer margin; exopod about twice as long as endopod; endopod proximally inserted.

Male: Carpus and distal part of merus of pereopod 1 ( Figure 22A ), pereopod 2 and, to a lesser extent, pereopod 3 with a brush of pointed setae. Pereopod 7 ( Figure 22B ) ischium with slightly convex sternal margin and a longitudinal depression and a setose area on rostral surface; merus elongated, without peculiar structures. Pleopod 1 ( Figure 22C ) exopod with long medial lobe almost three times as long as wide, with some short setae along its margin and a broadly rounded apex; endopod with distal part with almost parallel sides and a tuft of short setae at apex. Pleopod 2 ( Figure 22D ) endopod distinctly longer than exopod. Pleopod 3–5 exopods as in Figure 22E–G .

Etymology

The species is named after the Oued Laou basin, where the specimens were collected.

Remarks

In having the male pleopod 1 exopod with a long medial lobe S. laouensis is similar to S. gaditanus , S. fuscovariegatus and S. gibbosus sp. nov. It is readily distinguishable from S. gaditanus in having the male pleopod 1 exopod with broadly rounded instead of triangular apical part and shorter uropodal exopods; from S. fuscovariegatus in the less protruding lateral lobes of cephalon (see Figure 3A in Vandel 1956b) and comparatively longer and thinner uropods; and from S. gibbosus in lacking the hump on the male pereopod 7 merus and distinctly thinner medial lobe of the male pleopod 1 exopod.

Figures

Figure 3. Graeconiscus thermophilus from St. 8, ♂: (A) adult specimen, dorsal view; (B) pereonites 6, 7 and pleon, ventral view; (C) pereopod 7.

Figure 21. Soteriscus laouensis sp. nov. from St. 16, paratype ♀: (A) adult specimen, dorsal view; (B) dorsal scale-seta; (C) co-ordinates of noduli laterals; (D) cephalon, dorsal view; (E) cephalon, frontal view; (F) cephalon and pereonite 1, lateral view; (G) pereonite 7, right side; (H) pleonites 4, 5, telson and uropods; (I) antennule; (J) antenna; (K) uropod, lateral view.

Figure 22. Soteriscus laouensis sp. nov. from St. 16, paratype ♂: (A) pereopod 1; (B) pereopod 7; (C) genital papilla and pleopod 1; (D) pleopod 2; (E) pleopod 3 exopod; (F) pleopod 4 exopod; (G) pleopod 5 exopod.