Ampelisca rocasensis, Souza-Filho & Souza & Valério-Berardo, 2009

Souza-Filho, J. F., Souza, A. M. T. & Valério-Berardo, M. T., 2009, Description of four new species of the genus Ampelisca (Amphipoda, Ampeliscidae) from the northeastern and southeastern coasts of Brazil and designation of a neotype for Ampelisca soleata Oliveira, 1954, Journal of Natural History 43 (37 - 38), pp. 2391-2423 : 2409-2414

Ampelisca rocasensis sp. nov.

( Figure 11–13 )

Material examined

Holotype female 8.6 mm, Atol das Rocas, Rio Grande do Norte State (3°20.4′ S, 38°10.8′ W), REVIZEE Score NE #130A, 70.7 m, bioclastic sand, N. Oc. Antares col., 14 November 2000, MNRJ 21520 . Paratypes: Atol das Rocas, Rio Grande do Norte (3°20.4′ S, 38°10.8′ W), REVIZEE Score NE #130 A, N. Oc. Antares col., 70.7 m, bioclastic sand, 14 November 2000, MNRJ 21521 , 4 females . REVIZEE Score NE #75, 1°29.4′ S, 38°41.4′ W, North Chain , N. Oc. Antares col., 54 m, bioclastic sand, 7 June 1998, MNRJ 21522 , 1 female . REVIZEE Score NE #169, 9°27′ S, 35°7.2′ W, N. Oc. Antares col., 42 m, bioclastic sand, 2 December 2000, MNRJ 21523 , 1 female .

Etymology

This species name is derived from the type locality, Atol das Rocas, Rio Grande do Norte State, Northeastern Brazil .

Diagnosis

Head with anteroventral margin oblique. Antenna 1 shorter than antenna 2 peduncle. Antenna 2 longer than body length. Pereopod 7 basis posterior margin obliquely rounded crenulate; ischium shorter than merus; merus posterodistal lobe reaching to end of carpus; carpus anterior margin with a notch bearing two robust setae; propodus longer than carpus (1.5 times), length 2.3 times breadth; dactylus subequal to propodus. Epimeron 3 posteroventral corner drawn out into a spine. Urosomite 1 with dorsal margin drawn out, saddle-shaped. Uropod 2 outer ramus with a long apical robust seta. Uropod 3 rami foliaceous and lanceolate. Telson with each lobe with two dorsal long setae and notched pointed at apex, each notch bearing three simple setae.

Description

Holotype, female 9.6 mm. Head ( Figure 11 ) longer than deep, shorter than first three body segments combined, anteroventral margin oblique. Two pairs of corneal lenses present, strongly developed. Antenna 1 ( Figure 11 ) shorter than antenna 2 peduncle, peduncular article 2 3.0 times longer than article 1 and 3.5 times longer than article 3; flagellum with 14 articles, longer than peduncle. Antenna 2 ( Figure 11 ) longer than body length, fourth peduncular article 1.1 times longer than fifth peduncular article; flagellum with 31 articles, longer than peduncle.

Mandible ( Figure 11 ) accessory setal row with nine setae; palp article 2 not inflated, outer margin long simple setae, article 3 0.8 times article 2, with setae on outer, inner and apical margins. Maxilla 1 ( Figure 11 ) inner plate with one apical seta; outer plate with 11 serrate robust setae; palp article 2 with 3 distal cusps accompanied by five robust setae and two facial setae. Maxilliped ( Figure 11 ) inner plate rectangular distally with two robust setae and 10 plumose setae on distal margin; outer plate reaching to one-third of the palp article 3, bearing nine chisel-shaped robust setae along inner margin and three apical robust setae; palp article 3 with article 4 inserted at distal midlength, article 4 without setules on the inner margin. Upper lip, lower lip and maxilla 2 with basic characters for the genus.

Coxae 1–4 ( Figure 12 ) longer than broad. Coxae 1 and 2 with a row of plumose setae on ventral margins and a deep notch on posteroventral corner. Coxa 1 ( Figure 12 ) distally widened. Gnathopod 1 ( Figure 12 ) basis weakly inflated distally, with long simple setae on posterior margin and short simple setae on anterior margin; ischium with two long setae on posterodistal corner; merus with long setae along posterior margin; carpus 1.2 times propodus length, both articles with posterior margins with pinnate setae; dactylus curved, with three setules pinnate along inferior margin. Gnathopod 2 ( Figure 12 ) basis weakly inflated distally, with long simple seta on both margins; ischium and merus with long setae on posterior margins; carpus 1.9 times propodus length, both articles with posterior margins with pinnate setae; dactylus slightly curved, with three setules pinnate along inferior margin. Pereopod 3 and 4 ( Figure 12 ) similar in shape but the fourth is more massive and setose than third, both with dactyli slightly longer than combined lengths of carpus and propodus (1.1 times). Pereopod 3 ( Figure 12 ) merus with six long plumose setae along half of posterior margin and one long plumose seta on anterodistal margin, anterodistal corner not produced; carpus with long plumose setae posterior margin; propodus with three plumose setae on half of anterior margin and four simple setae on anterodistal corner. Pereopod 4 ( Figure 12 ) basis with plumose setae on anterodistal margin and long plumose and short simple setae along posterior margin; merus length three times breadth, heavily plumose setae on both margins; carpus with plumose setae on posterodistal corner; propodus with long simple setae on posterodistal corner. Pereopod 5 ( Figure 12 ) basis subovoid, anterior margin with six plumose setae; carpus 1.1 times longer than propodus and produced posterodistally, anterior margin with long simple setae, posterior margin with three combs of robust setae (2–3–3), bearing three long and two short setae on posterodistal corner; propodus anterior margin with eight simple setae, posterior margin with two robust setae; dactylus short, with three apical cusps. Pereopod 6 ( Figure 12 ) basis subovoid, anterior margin with four long plumose and 11 short simple setae and one robust seta in anterodistal corner; carpus longer than propodus (1.3 times), posterior margin with comb of robust setae (2–4), posterodistal corner drawn out, bearing three long setae and four robust setae; anterior margins of carpus and propodus with a row of setae; anterodistal corner of the propodus with two long setae; dactylus short, with four apical cusps. Pereopod 7 ( Figure 13 ), basis posterior margin obliquely rounded crenulate, reaching to middle of merus, with plumose setae on ventroposterior margin; ischium shorter than merus; merus posterodistal lobe reaching to end of carpus, lobe margin with six plumose setae; carpus anterior margin with a notch bearing two robust setae, anterodistal corner with one simple seta; propodus longer than carpus (1.5 times), length 2.3 times breadth, anterodistal corner with three robust setae; dactylus subequal in length to propodus, curved anterodistally.

Epimeron 3 ( Figure 13 ) posteroventral corner drawn out into a spine. Urosomite 1 ( Figure 11 ) with dorsal margin produced saddle-shaped. Uropod 1 ( Figures 11 and 13 ) extending to end of uropod 2 peduncle, peduncle subequal in length to rami, inner and outer margin with five robust setae; inner ramus subequal in length to outer ramus, with three robust setae on inner margin; outer ramus with three short robust setae on outer facial margin. Uropod 2 ( Figure 13 ) peduncle longer than rami, with a comb of five robust setae on apical inner corner and four robust setae on outer margin; rami subequal in length; outer and inner facial margin of inner ramus with a row of robust setae; outer ramus with a long apical robust seta and five robust setae on inner margin. Uropod 3 ( Figure 13 ) peduncle shorter than rami, with three robust setae on inner margin; rami foliaceous and lanceolate, outer ramus with one proximal plumose seta, and one midway robust seta on outer margin and distal and subdistal setae on inner margin; inner ramus with plumose setae about half length of inner margin, and with simple and plumose setae along outer margin. Telson ( Figure 13 ) cleft (0.7 times), each lobe with two dorsal long setae and notched pointed at apex, each notch bearing three simple setae.

Remarks

Ampelisca rocasensis sp. nov. is closely related to A. indentata Barnard 1954 and A. pugetica Stimpson 1864 in having urosomite 1 with dorsal margin drawn out as saddle shaped, posterior lobe on merus of pereopod 7, outer ramus of uropod 2 with long distal seta, and rami of uropod 3 lanceolate. However, A. rocasensis sp. nov. differs from both by the following combination of characters: antenna 2 longer than body length; pereopod 7 with outer margin of basis crenulated and a relation merus– ischium and carpus–dactylus longer in length; outer ramus of uropod 3 with one robust seta midway on outer margin and inner margin naked.

Moreover, in having antenna 2 longer than body length, urosomite 1 with dorsal margin saddle-shaped, pereopod 7 posterior margin of basis crenulate and outer ramus of uropod 3 lanceolate and with halfway robust setae, A. rocasensis sp. nov. is similar to another species recently described for the Brazilian coast, A. youngi Valério-Berardo, 2007 . However, the former can be distinguished from A. youngi by antenna 1 shorter than peduncle of antenna 2, inner plate of maxilliped with two chisel-shaped robust setae, coxa 2 bearing a notch on posteroventral corner, dactyli of pereopods 5 and 6 with three and four cusps (versus one and three), respectively, pereopod 7 with propodus 1.5 times carpus length (versus twice carpus length), epimeron 3 with posteroventral corner produced into a spine, peduncles of uropods 1 and 2 with less robust setae.

Geographic distribution

Brazil: Fernando de Noronha Chain (including Atol das Rocas).

Figures

Figure 11. Ampelisca rocasensis sp. nov., holotype, female 8.6 mm, Atol das Rocas, Rio Grande do Norte State (3°20.4′ S, 38°10.8′ W), REVIZEE Score NE #130A, N. Oc. Antares, 14 November 2000, MNRJ 21520. Scale bar 0.1 mm.

Figure 12. Ampelisca rocasensis sp. nov., holotype, female 8.6 mm, Atol das Rocas, Rio Grande do Norte State (3°20.4′ S, 38°10.8′ W), REVIZEE Score NE #130A, N. Oc. Antares, 14 November 2000, MNRJ 21520. Scale bar 0.1 mm.

Figure 13. Ampelisca rocasensis sp. nov., holotype, female 8.6 mm, Atol das Rocas, Rio Grande do Norte State (3°20.4′ S, 38°10.8′ W), REVIZEE Score NE #130A, N. Oc. Antares, 14 November 2000, MNRJ 21520. Uropod 3: Paratype, female, 6.0 mm, REVIZEE Score NE #75, 1°29.4′ S, 38°41.4′ W, N. Oc. Antares, 7 June 1998, MNRJ 21522. Scale bar 0.1 mm.