Chevalia marajoara

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 : 39-42

Chevalia marajoara nov. sp.

( Figs 10–12 )

Material examined. Holotype, hermaphrodite, 3.5 mm (dissected and drawn), Pará-Maranhão Basin, 0°45’N – 44º25’W, ship OceansatPeg I, 60 m, P. V. Castelões col., MZUSP 22283. Paratypes. 3 hermaphrodites, Pará- Maranhão Basin, 0°45’N – 44º25’W, Ship OceansatPeg I, 60 m, P. V. Castelões col., MZUSP 22284.

Etymology. The name refers to the first humans that settled on the savannas of Marajo Island, at the Amazon River delta.

Description. Based on holotype, hermaphrodite, 3.5 mm (MZUSP 22283). Eyes of medium size, partially situated in lateral lobe of the head, proximal margin of lateral cephalic lobe rounded. Antenna 1 1.3 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 8 articles; flagellum accessory 3–articulate, article 1 shorter than article 2, article 3 rudimentary, 1/8 article 2 length. Antenna 2 shorter than antenna 1, article 4 subequal in length to article 5; flagellum with 4 articles. Mandible palp 3 X longer than body of mandible, article 1 shorter, articles 2 1.3 X article 3 length; incisor and lacinia mobilis with 3 teeth, accessory setal row with 3 setae, molar process triturative. Lower lip, inner lobes and outer lobes separated, inner lobes large and fleshy. Maxilla 1 inner plate with marginal row of setules; outer plate with 8 robust setae; palp 2–articulated with 3 apical robust setae and 2 subapical setae. Maxilla 2 outer plate longer and slightly broader than inner plate, both plates apically setose, inner plate with oblique facial row of setae. Maxilliped inner plate rectangular distal margin with 2 robust setae and 6 plumose setae; outer plate reaching to half of length of palp article 2, with 5 robust setae along medial margin and apically with 2 long plumose setae; palp article 2 longer than articles 3 and 4 combined (1.6 X), article 4 with 1 long distal robust seta.

Coxae 1 and 2 larger than coxae 3–7, coxa 1 slightly produced forward, coxa 2 with anteroventral angle strongly produced. Gnathopod 1 slender; carpus and propodus subequal in length, both articles with row of plumose setae along posterior margin, palm oblique; dactylus with a small seta on inner distal margin. Gnathopod 2 coxal gill reaching more than 1/2 of basis length; basis moderately slender, length 2.1 X width; carpus weakly lobed on posterodistal corner, anterodistal margin straight, anterior margin longer than posterior margin (3 X); propodus massive, 1.8 X of carpus length; posterior margin with scarcely setose and subparallel to anterior margin; palm transverse, defined by rounded projection, inner margin sinusoidal and serrate; dactylus shorter than palm, naked. Three pairs of oostegites present, first as developed as with the others. Pereopods 3 and 4 similar in shape, scarcely setose; merus elongate and slightly inflated, anterodistal corner weakly lobed. Pereopods 5–7 similar in shape, ratio length 0.56:0.9:1. Pereopod 5 basis ovate, length 1.4 X width, posterior margin with three setae; merus 0.9 X of carpus length; carpus reniform, with posterodistal corner produced, with 2 submarginal robust setae and 1 long seta; propodus length 2.5 X width; dactylus with 1 large accessory spine. Pereopod 6 basis ovate, length 1.2 X width, posterior margin with 4 setae; merus 1.4 X of carpus length; carpus reniform, with posterodistal corner produced, with 2 submarginal robust setae and 1 plumose setae; propodus length 2.85 X width; dactylus with 1 large accessory spine. Pereopod 7 basis ovate, not produced on posteroventral angle, length 1.75 X width, posterior margin with 5 setae; merus 1.4 X of carpus length, with antero and posterodistal angles slightly produced; carpus reniform, with posterodistal corner rounded produced, with 2 submarginal robust setae and 2 long setae; propodus length 3.1 X width; dactylus with 1 large accessory spine and 1 setule.

Posterodorsal margins of pereon 7 and pleon 1–3 with a pair of long simple setae. Epimera 1–3, margin posterior straight, posteroventral corner rounded. Uropod 1 peduncle subequal in length to rami; inner ramus with inner margin with 18 large medial serrate spines, extending on almost entire medial margin; outer ramus with all outer margin and sub apical inner margin with lateral setules, apical margin with 2 robust setae, outer margin with a proximal long simple seta. Uropod 2 peduncle shorter than rami, naked; rami subequal in length, outer ramus without marginal simple seta on outer margin, apical margin with 3 robust setae and 1 short spine; inner ramus naked. Uropod 3 peduncle shorter than rami; rami with apical plumose and simple setae. Telson subquadrate, distal margin concave and with a middle rounded process, with long simple setae.

Remarks. Chevalia marajoara sp. nov. also belongs to group III of Chevalia . Nevertheless C. marajoara sp. nov. differs from them by the following combinations of characters: proximal margin of lateral cephalic lobe rounded; mandible palp elongate; three pairs of oostegites present; posterodistal corner of carpus with 2 submarginal robust setae; uropod 1 inner ramus with inner margin with 18 large medial serrate spines, extending on almost entire medial margin and uropod 2 rami subequal in length.

Geographic distribution. Known only from type locality, Pará-Maranhão Basin (0°45’N 44º25’W).

Depth range. Specimens were collected at 60 m.

Figures

FIGURE 10. Chevalia marajoara nov. sp., holotype, hermaphrodite (3.5 mm), Pará-Maranhão Basin, MZUSP 22283. Scale bars 0.1 mm.

FIGURE 11. Chevalia marajoara nov. sp., holotype, hermaphrodite (3.5 mm), Pará-Maranhão Basin, MZUSP 22283. Scale bars 0.1 mm.

FIGURE 12. Chevalia marajoara nov. sp,. holotype, hermaphrodite (3.5 mm), Pará-Maranhão Basin, MZUSP 22283. Scale bars 0.1 mm.