Chevalia thomasi, Souza-Filho, Jesser F., Souza, Ana Maria T. & Valério-Berardo, Maria Teresa, 2010

Souza-Filho, Jesser F., Souza, Ana Maria T. & Valério-Berardo, Maria Teresa, 2010, Six new species of the genus Chevalia Walker, 1904 (Amphipoda, Corophiidea, Chevaliidae) from Brazilian waters, with a key to world species of the genus, Zootaxa 2713, pp. 25-51 : 46-49

Chevalia thomasi sp. nov.

( Figs 16–18 )

Material examined. Holotype, female, 5.1 mm, Baía de Todos os Santos, Bahia, #P3, 13º02.410’S 38º37.8’W, 16 m, col. O. Falcão, MNRJ 15794. Paratypes. 1 female (dissected and drawn), 5.3 mm, Revizee Central #17, 18°39.78’S 37°52.2’W, dredge, supply boat N/RB Astro Garoupa col., 29 November 2001, 65 m, MNRJ 21958. 3 females, Revizee Central #17, 18°39.78’S 37°52.2’W, dredge, supply boat N/RB Astro Garoupa col., 29 June 2001, 65 m, MNRJ 21956. 7 females, Revizee Central C6 R2 #1-1, 19°46.6’S 39°31.08’W, Box-corer, supply boat N/RB Astro Garoupa col., 15 June 2002, 92 m, MNRJ 21957. 4 females, Revizee Central #Y7, 20°50.94’S 40°10.02’W, dredge, supply boat N/RB Astro Garoupa col., 77 m, 28 June 2002, MNRJ 21954. 2 females, Revizee Central #25R, 19°31.62’S 38°46.08’W, dredge, supply boat N/RB Astro Garoupa col., 28 June 2002, 65 m, MNRJ 21955.

Etymology. Named in honor to Dr. James Darwin Thomas (Nova Southeastern University Oceanographic Center, Florida) for his contributions on amphipods taxonomy.

Description. Based on holotype, female, 5.1 mm (MNRJ 15794) and paratype, female, 5.3 mm (MNRJ 21958). Eyes of large medium size, entirely situated in lateral lobe of the head, proximal margin of lateral cephalic lobe rounded. Antennae densely setose. Antenna 1 1.5 X longer than the length of head and first 4 pereon segments combined; peduncular article 3 0.6 X longer than article 1, primary flagellum with 7 articles; flagellum accessory 3–articulate, article 1 shorter than article 2, article 3 rudimentary, 1/10 article 2 length. Antenna 2 as long as antenna 1; article 4 subequal in length to article 5; flagellum with 5 articles. Mandible palp 2 X longer than body of mandible, article 1 very shorter, articles 2 1.1 X longer than article 3; incisor and lacinia mobilis with 4 and 5 teeth respectively, accessory setal row with 5 setae, molar process triturative. Lower lip, inner lobes and outer lobes separated, inner lobes large and fleshy. Maxilla 1 inner plate with marginal setules; outer plate with 6 robust setae; palp 2–articulated with five apical robust setae and three subapical plumose setae. Maxilla 2 outer plate longer than inner plate, with oblique facial row of setae on outer margin; outer plate with a row of setae on apical margin. Maxilliped inner plate rectangular with distal margin with 4 robust setae and 4 plumose setae; outer plate reaching to 1/2 of length of palp article 2, with 4 robust setae and row of plumose setae on medial and facial margin and apically with 1 plumose and 1 robust setae; palp, article 2 longer than articles 3 and 4 combined (1.3 X), article 4 with 1 long distal robust seta.

Coxae 1 and 2 larger than coxae 3–7, both with anteroventral angle weakly produced. Gnathopod 1 slender; carpus 1.3 X longer than propodus, both articles with row of simple and plumose setae along posterior margin, palm oblique; dactylus naked. Gnathopod 2, coxal gill reaching about 2/3 of basis length; basis moderately slender, length 1.5 X width; carpus subequal in length to propodus, not lobate; propodus posterior margin with a row of simple setae, palm transverse, with shallow “U”–excavation near hinge of dactylus, defined by weakly produced blunt process, dactylus shorter than palm, with a small acute projection near articulation of propodus. Three pairs of oostegites present. Pereopods 3 and 4 scarcely setose; merus elongate, anterodistal and posterodistal corners with a lobe weakly rounded. Pereopod 5 basis ovate, as long as width posterior margin with 4 setae; merus 1.5 X of carpus length, with antero and posterodistal angles produced; carpus reniform, with posterodistal corner rounded produced, with 1 submarginal robust seta and 1 simple seta; propodus length 2.2 X width; dactylus with 1 large accessory spine and 1 plumose seta. Pereopod 6 basis ovate, length 1.7 X width, posterior margin with 6 setae; merus 2.2 X of carpus length, with antero and posterodistal angles produced; carpus reniform, with posterodistal corner produced, with 1 submarginal robust seta and 1 seta; propodus length 4 X width; dactylus with 1 large accessory spine. Pereopod 7 basis rectangular, length 2.8 X width, posterior margin with 13 setae, posterodistal angle not produced; merus 1.6 X of carpus length, with anterodistal angle produced; carpus reniform,, with 1 submarginal robust seta and 2 long setae; propodus length 4 X width; dactylus with 1 large accessory spine.

Posterodorsal margins of pleon 1–3 and pleon 1–3 with a pair of long simple setae. Epimera 1–3, posteroventral margin slightly sinuose posteroventral corner rounded, without a notch. Uropod 1 peduncle subequal in length to inner ramus, with three setae on outer margin; inner ramus 1.2 X longer than outer ramus, with inner margin with 11 large proximomedial serrate spines; outer ramus apical margin with five spines and three robust setae. Uropod 2 peduncle shorter than inner ramus, with 1 seta on outer margin; outer ramus shorter than inner ramus, apical margin with 6 spines and three robust setae, inner ramus naked. Uropod 3 peduncle shorter than rami; rami with apical plumose setae. Telson subquadrate, distal margin convex, with a rounded middle process; 2 rows lines of small spines and three distolateral plumose setae in each side.

Remarks. Chevalia thomasi sp. nov. is similar to C. inaequalis , both included in the group II, by the pereopod 7 basis rectangular lacking produced posterodistal corner. But the new species is characterized by the diagnostic features of the accessory flagellum 3–articulate; carpus of gnathopod 2 as long as propodus; and the only 1 submarginal robust seta on posterodistal corner of pereopods 5–7.

Geographic distribution. Bahia to Espírito Santo (18º– 20ºS)

Depth range. 16 to 92 m depth.

Figures

FIGURE 16. Chevalia thomasi sp. nov., paratype female (5.4 mm), Revizee Central # 17, MNRJ 21958. Scale bars 0.1 mm.

FIGURE 17. Chevalia thomasi sp. nov., paratype female (5.4 mm), Revizee Central # 17, MNRJ 21958. Scale bars 0.1 mm.

FIGURE 18. Chevalia thomasi sp. nov., paratype female (5.4 mm), Revizee Central # 17, MNRJ 21958. Scale bars 0.1 mm.