Ampelisca youngi

Valério-Berardo, Maria Teresa, 2007, Description of three new species of Ampelisca (Crustacea: Amphipoda: Ampeliscidae) from Southwestern Atlantic, with a key of the genus for Brazilian species, Zootaxa 1626, pp. 25-37 : 31-37

Ampelisca youngi

( Figs. 5–6 )

Material examined: Holotype, female, 8mm, 23º25’S – 42º27’W, 34 m, fine sand, RV W. Besnard, 03/IX/70, MZUSP 17215. Paratypes: 23º25’S – 42º27’W, 34 m, fine sand, RV W. Besnard, 03/IX/70, MZUSP 17217, 2 females; 22°06’S – 40°10’W, 77m, medium sand, RV Astro Garoupa, 24/II/1990, MZUSP 17216, 1 male; 23º25’S – 42º27’W, 34 m, fine sand, RV W. Besnard, 03/IX/1970, MNRJ 20454, 2 females.

Etymology: Named in tribute to Paulo S. Young (in memoriam) in recognition of his significant contribution to Brazilian carcinology.

Diagnosis: Head with anteroventral margin oblique. Antenna 2 longer than body. Pereopod 7, basis posterior margin rounded and reaching to middle of carpus, merus posterior lobe extending end of carpus, carpus anterior margin notched with 1 robust seta and with anterodistal margin lobed with 3 robust setae; propodus longer than carpus, not stout, dactylus slightly shorter than propodus. Epimeron 3 postero-ventral corner quadrate. Urosomite 1 with saddle-shaped dorsal carina. Uropod 2 outer ramus with a long apical robust seta. Uropod 3 rami foliaceous with plumose setae on inner margins. Telson apices of lobes pointed and notched.

Description: Holotype, female 8 mm. Head ( Fig. 5 ) shorter than first 3 body segments combined, with antero ventral margin oblique. Antenna 1 ( Fig. 5 ) subequal in length to antenna 2 peduncle, peduncular article 2 longer than articles 1 and 3, without setae on ventral margin; flagellum with 26 articles. Antenna 2 longer than body, peduncular article 4 subequal in length to article 5; flagellum with 18 articles. Mandible (fig. 5) with 7 robust setae in the accessory setal row; palp article 2 not inflated and with inner margin with long simple setae, article 3 shorter than article 2 (0.8 X) with setae on both margins. Maxilla 1 ( Fig. 5 ) inner plate with 2 apical setae; outer plate with 11 setal-teeth; palp article 2 with 3 distal cusps accompanied by 4 robust setae and 5 facial setae. Maxilliped ( Fig. 5 ) inner plate rectangular distally with 7 plumose setae; outer plate reaching to end of palp article 2, bearing 7 chisel-shaped robust setae along margin; palp normal for the genus, article 3 clavate. Upper lip, lower lip and maxilla 2 ( Fig. 5 ) with basic characters for the genus.

Coxae 1 –– 4 longer than broad. Coxae 1 and 2 ( Fig. 5 ) with marginal a row of plumose setae on ventral margins. Coxa 1 distally widened, posteroventral corner with a notch. Gnathopod 1 ( Fig. 5 ) basis slightly inflated distally, posterior and anterior margins with a row of long simple and plumose setae; isquium and merus with setae on posterior margin; carpus longer than propodus (1.3 X), both articles posterior margins with pectinate setae; dactylus slightly curved, with 3 setules along inferior margin. Gnathopod 2 ( Fig. 5 ) basis inflated distally with few long simple and plumose setae on both margins; merus with plumose setae on posterior margin; carpus longer than propodus (1.3 X), with long setae on posterior margin; propodus with pectinate setae on posterior margin; dactylus short, curved, bearing 4 setules along inferior margin. Pereopod 3 and 4 ( Fig. 5 ) similar in shape but the fourth is slightly more massive and setose than third, both pereopods with elongate dactyli, longer than combined lengths of propodus and carpus. Pereopod 3 merus with a subapical plumose seta on posterior margin and few simple setae on anterior margin, antero-distal corner not produced; carpus with long plumose setae on posterior margin. Pereopod 4 basis and merus with long plumose setae on both margins; isquium and carpus with long plumose setae on posterior margin; merus length 2 X breadth; propodus both margins with simple setae. Pereopod 5 ( Fig. 6 ) basis subovoid, anterior margin with long setae; carpus subequal in length to propodus, posterodistal corner produced and bearing 1 long seta and 2 robust setae, anterior margin with a row of setae, posterior margin with 4 set of comb robust setae; dactylus short, with 1 apical cusp. Pereopod 6 ( Fig. 6 ) basis subquadrate, anterior margin with long plumose and simple setae; carpus longer than propodus (1.4 X), posterodistal corner produced and bearing 2 long simple setae, 2 robust setae and 1 plumose seta, posterior margin with 2 sets of comb robust setae, anterior margin with row of robust setae and simple setae; dactylus short, with 4 apical cusps. Pereopod 7 ( Fig. 6 ) basis posterior margin rounded and reaching to middle of carpus, with plumose setae on posterodistal margin; ischium longer than merus; merus posterior lobe extending end of carpus, with plumose setae; carpus anterior margin notched, with one robust seta on notch, anterodistal corner lobed and bearing 3 robust setae; propodus twice longer than carpus, not stout, length 2.5 X breadth, with a long facial plumose setae, anterodistal corner with 3 robust setae and a plumose seta, posterodistal corner with 2 robust setae; dactylus long, slightly shorter than propodus, curved distally.

Epimeron 3 ( Fig. 6 ) posteroventral corner quadrate. Urosomite 1 ( Fig. 6 ) dorsal margin produced into a saddle-shaped carina. Uropod 1 ( Fig. 6 ) extending to middle of uropod 2 rami, peduncle shorter than rami, with 3 robust setae on each side; inner ramus slightly longer than outer ramus, with 5 robust setae on inner margin, outer ramus nacked. Uropod 2 (fig. 6) peduncle longer than rami with a comb of robust setae on apical inner margin; inner margins of both rami with a row of robust setae; outer ramus shorter than inner ramus with a long apical robust seta. Uropod 3 ( Fig. 6 ) peduncle with 3 robust setae on inner margin; rami foliaceous and longer than peduncle, inner margins of both rami with plumose setae; outer ramus with a row of robust setae on outer margin. Telson cleft (0.7 X) with dorsal setae, apical margin pointed and notched medially, each notch bearing 1 setae and 1 pectinate seta.

Male, 9.0mm. Differing from the female by antennal peduncles with brush setae; urosomite 1 dorsal margin produced into a saddle-shaped carina deeper than female urosomite 1; uropod 3 rami setose in both margins and telson without dorsal setae.

Remarks: Ampelisca youngi nov. sp. belongs to the group of species bearing antenna 2 longer than body length, head anteroventral margin oblique, uropod 3 rami foliaceous with plumose setae and epimeron 3 posteroventral corner quadrate, characters shared with A. jaffaensis Bellan-Santini & Kaim-Malka, 1977 , A. ledoyeri Bellan-Santini & Kaim-Malka, 1977 , A. provincialis Bellan-Santini & Kaim-Malka, 1977 , A. pseudospinimana Bellan-Santini & Kaim-Malka, 1977 , A. ruffoi Bellan-Santini & Kaim-Malka, 1977 and A. vervecei Bellan-Santini & Kaim-Malka, 1977 . However, Ampelisca youngi nov. sp. differs from all those species by peropod 7 merus posterior margin lobed and carpus with a notch on anterior margin; uropod 2 outer ramus with a long apical robust seta and urosomite 1 with a saddle-shaped carina. Ampelisca youngi nov. sp. also differs from A. ruffoi and A. vervecei by antenna 1 subequal in length to peduncle of antenna 2.

Figures

FIGURE 5. Ampelisca youngi sp. nov.: female, 8 mm, holotype, MZUSP 17215.

FIGURE 6. Ampelisca youngi sp. nov.: female, 8 mm, holotype, MZUSP 17215; male 6.5 mm, paratype, MZUSP 17216.