Eurydice marisrubri, Jones, David Alan & Nithyanandan, Manickam, 2012

Jones, David Alan & Nithyanandan, Manickam, 2012, Taxonomy and distribution of the genus Eurydice Leach, 1815 (Crustacea, Isopoda, Cirolanidae) from the Arabian region, including three new species, Zootaxa 3314, pp. 45-57 : 51-55

Eurydice marisrubri sp. nov.

( Figs 3 , 4 )

Material examined. Holotype. Male ( SMF 34845): sta. RS237, 2 km off Eilat, Israel, Red Sea, neuston coll. L. Fishelson, 21 Oct 1986.

Paratypes: 3 Males, 2 females ( SMF 34846): sta. RS112, near Eilat, Israel, Red Sea, ichthyoplankton, 50 males and females juv. ( SMF 39706), near Eilat, Israel, Red Sea. Sta. R26, coll. L. Fishelson, 1985–1986.

Description. Male holotype body 3.7 mm in length, 2.9 times longer than greatest width at pereonites 4and 5. Cephalon anterior bluntly rounded, eyes large with 7–8 vertical and 6–7 horizontal ocelli. Coxae 2–7 with slightly produced acute posterolateral lateral margins. Pleonites 2–5 with crenulated posterior margins, ventral margins of all pleonites acute. Pleotelson with lateral margins crenulate, slightly broader than long and 4.4 times wider than the posterior margin which is truncate. Posterior margin with 5 subequal teeth, 6 plumose setae and 2 submarginal setae.

Antennule reaching to posterior edge of eye, third peduncular article longest bearing 4 simple setae on anterodistal angle. Flagellum of 4 articles with article 1 equal in length to combined articles 2–4. Terminal article with 6 setae, one of which is more than twice length of others.

Antenna reaching to posterior margin of pleonite 3 length of peduncular articles 2 and 3 equal to length of peduncular article 4. Peduncular article 3 with 4 setae on anterodistal margin and 1 seta on posterodistal angle. Peduncular article 4 with 2 single setae and 2 groups of 2 setae on anterior margin and 2 setae on posterior margin. Flagellum of 14 articles, distal articles twice length of proximal, each with 2 setae on anterodistal margin; no plicate processes present. Two terminal setae present, one 8 times, one 3 times length of distal article.

Mandible spine row with 6 spines, molar process anterior margin with 14 spines. Terminal article of mandibular palp 2.4 times longer than wide bearing 7 setae, article 2 with a single seta. Maxillule lateral lobe with 13 robust setae on gnathal surface, medial lobe with 3 circumplumose setae and a single simple seta. Maxilla lateral lobe with 4 terminal setae, middle lobe with 4 setae and medial lobe with 3 simple and 1 plumose setae. Maxilliped palp with all articles entire, terminal article broader than long with 6 setae; endite with a single plumose seta and short simple seta.

Pereopods 1–3 moderately setose, all figured. Pereopod 1 with robust seta opposing dactylus half length of dactylus, posterior margin of ischium without robust setae and a single simple seta; merus without anterodistal robust seta but 3 simple setae. Pereopod 2 with 2 robust and 6 simple setae on ischium posterior margin; merus with anterodistal robust seta and 6 simple setae. Pereopod 3 with 2 robust setae on the posterodistal margin of the propodus and a single robust seta on the posterior margin; carpus with 4 posterodistal robust setae and a single robust seta on the posterior margin. Ischium with 4 robust setae on the posterodistal margin and a group of 3 and 2 robust setae on the posterior margin; basis with 3 simple setae, one reaching two thirds of length of ischium.

Pereopod 7 moderately setose, propodus anterior margin with 5 robust setae; posterior margin with 3 robust and 3 simple setae. Merus with 6 robust and 3 simple setae on anterior margin, posterior margin with 5 robust and 5 simple setae. Carpus with 3 robust and 2 simple setae on posterodistal margin and a single robust and simple seta on posterior margin. Ischium with 3 robust and 4 simple setae on anterior margin and 2 robust and 3 simple setae on posterior margin.

Pleopod 1 with exopod longer than endopod and 1·45 times wider, exopod with 17 plumose setae, endopod with 12 plumose setae. Pleopod 2 with 23 plumose setae on exopod and 17 plumose setae on endopod. Appendix masculina straight, slightly expanded distally with curved tip bearing a short blunt process. Microtrichs present on distal third of appendix masculina which extends beyond endopod by one third of its length. Uropod endopod 1·5 times length of exopod, distinctly triangular in shape, bearing 13 plumose and 2 robust setae on posterior margin. Exopod with 5 simple setae and 1 robust seta on posterolateral angle and 6 plumose plus 2 robust setae on posterior margin. Rami do not reach posterior margin of pleotelson.

Female: As for male but body broader; antenna shorter reaching posterior margin of pereonite 5, terminal seta equal in length to terminal article of flagellum.

Colour. Brown in alcohol with small black chromatophores on dorsal surface of body but with no ventral pigmentation.

Remarks. The characters which diagnose E. marisrubri are the narrow truncate posterior pleotelson margin with crenulated lateral margins and 5 equal sized apical teeth and the absence of robust setae. In addition the crenulated posterior margins to pleonites 2–5 and straight appendix masculina with expanded apex and angled apical projection. This species is similar to E. woka Bruce, 1986 , one of a group of subtidal Australian Eurydice ( Bruce 1986) . Eurydice marisrubri is separated by the presence of 6 plumose setae on the posterior margin of the pleotelson ( E. woka has 4); the crenulated posterior margins of pleonites and pleotelson, together with the length and shape of the appendix masculina. These and other features separate E. marisrubri from E. inermis , E. humilis Stebbing (1910) and all other subtidal species.

Etymology. This species appears to be common and have a wide range in the Red Sea (Yanbu to Eilat) and is named after the sea which it inhabits.

Figures

FIGURE 3. Eurydice tridentata sp. nov. Holotype (SMF 34843): a, b, paratypes (SMF 34844) Ƥ: c – k. a, lateral view; b, dorsal view; c, antennule, detail of terminal articles; d, antennal peduncle and detail of tip; e, mandible; f, maxillule; g, maxilliped palp; h, pereopod 1, i, pereopod 2; j, pereopod 3; k, pereopod 7. Horizontal scale = 1.0 mm, vertical scale = 0.1 mm.

FIGURE 4. Eurydice marisrubri sp. nov. Holotype (SMF 34845): a, b, paratypes (SMF 34846) Ƥ: c – m. a lateral b, dorsal view; c, antennule; d, antennal peduncle; e tip of antenna; f mandible; g, maxillule; h, maxilla; i, maxilliped palp; j, pereopod 1; k, pereopod 2; l, pereopod 3; m, pereopod 7. Horizontal scale = 1.0 mm, vertical scale = 0.1 mm.