Ampelisca minuta, Valério-Berardo, Maria Teresa, 2008

Valério-Berardo, Maria Teresa, 2008, Six new species of deep water Ampeliscidae (Crustacea: Amphipoda) from Brazilian Coast, Zootaxa 1844, pp. 1-24 : 13-16

Ampelisca minuta sp. nov.

( Figs. 7–8 )

Material examined: Holotype: female, 2 mm, 22°31’12,47” S – 40°15’11,08”W, 750 m, R/V Astro Garoupa, 22/XI/2002 MNRJ 20534; Paratype: 1 female, 21°57’17,490”S – 39°56’01,080”W, R/V Astro Garoupa, 12/ XII/2002, MNRJ 20537.

Etymology: the species’ name refers to the small size of the specimens examined.

Diagnosis: Head anterodorsal corner with a small projection, anterior margin transversely truncate. Corneal lenses absent. Antenna 1 subequal in length to antenna 2 peduncle. Pereopod 7 basis posterodistal margin oblique and reaching middle of carpus, merus slightly produced anterodistally; carpus subequal in length to propodus and dactylus, propodus slender, dactylus bearing 2 subapical setae. Epimeron 3 posterior margin sligltly sinuous with a rounded projection on postero ventral corner. Uropod 1 peduncle and rami nacked. Uropod 3 rami lanceolate. Telson cleft (0.7 X), apices lobes blunt, with 1 robust and 1 plumose setae.

Description: Holotype, female 2 mm. Head ( Fig. 7 ) anterodorsal corner with a small projection, anterior margin transversely truncate, shorter than first three body segments combined. Corneal lenses absent. Antenna 1 ( Fig. 7 ) subequal in length to antenna 2 peduncle, article 2 1.2X longer than article 1, with ventral and dorsal setae on distal margin; flagellum with 3 articles, shorter than peduncle. Antenna 2 ( Fig. 7 ) shorter than body length, peduncular article 4 subequal in length to article 5; flagellum with 8 articles. Mandible ( Fig. 7 ) with 6 accessory setal row, mandibular palp stout, article 2 with 2 long setae on outer margin, article 3 0.4X article 2, with subapical and apical setae. Maxilla 1 ( Fig. 7 ) inner plate with 2 apical plumose setae, outer plate with 7 setal-teeth; palp article 2 provided with 2 distal cusps and 4 robust setae and 1 simple setae on distal margin. Maxilliped ( Fig. 7 ) inner plate rectangular distally with 2 apical robust setae and apical plumose and simple setae; outer plate not reaching to end of the palp article 2, with 4 chisel-shaped robust setae along medial margin and 2 apical robust setae and 2 submarginal simple setae; palp article 3 clavate. Upper lip, lower lip and maxilla 2 with basic characters for the genus.

Coxae 1–4 ( Fig. 7 ) longer than broad. Coxa 1 and 2 with plumose setae on ventral margins. Gnathopod 1 ( Fig. 7 ) basis inflated middistally with 3 simple setae on posterior margin, anterior margin with 1 medial seta; isquium and merus with 1 and 2 setae on posterodistal corner respectively; carpus subequal in length to propodus, both articles with pinnate setae on posterodistal margins; dactylus slightly curved and longer than to palm length. Gnathopod 2 ( Fig. 7 ) slender than gnathopod 1, basis with long setae on both margins; carpus 1.5 X propodus length, with 1 plumose seta on posterodistal corner, 2 simple and 1 pinnate setae on anterodistal corner; propodus very slender with 4 pinnate setae on posterior margin, 3 simple setae and 1 pinnate setae on anterodistal corner; dactylus 0.5 X propodus length. Pereopod 3 and 4 ( Fig. 7 ) similar in shape but the fourth is more massive and setose than third, both with dactyli longer than combined lengths of carpus and propodus (1.4 X). Pereopod 3 merus with only 1 plumose and 1 simple setae on distal corners, anterodistal corner not produced. Pereopod 4 basis and isquium with a row of plumose setae on posterior margin; merus length 3.8 X breadth, long plumose setae on both margins; carpus with plumose setae on distal margins. Pereopod 5 ( Fig. 8 ) basis subquadrate, anterior margin with 1 long plumose setae; carpus longer than propodus (1.1 X), slightly produced posterodistally, bearing 4 long simple setae; propodus very slender with 1 long simple and 2 plumose setae on posterodistal corner; dactylus very short, without apical cusp. Pereopod 6 ( Fig. 8 ) basis subovoid, anterior margin with 2 setae; carpus subequal in length to propodus, slightly produced posterodistally, bearing 3 long simple setae and i seta on anterodistal corner; propodus with 2 long simple setae on anterodistal corner; dactylus very short, without apical cusp. Pereopod 7 ( Fig. 8 ) basis posterior margin oblique and reaching to middle of carpus and with 1 long seta, and 1 subfacial seta on anterior margin; ischium subequal in length to merus; merus slightly produced anterodistally; carpus subequal in length to propodus, with 2 long setae on posterodistal corner; propodus not stout, length 1.7 X breadth, with 1 short seta on both distal corners; dactylus the same length to propodus, stout, bearing 2 subapical setae.

Epimeron 3 ( Fig. 8 ) posterior margin sligltly sinuous with a rounded projection on posteroventral corner. Urosomite 1 not produced dorsally into a carina. Uropod 1 ( Fig. 8 ) extending to end of uropod 2 rami, peduncle subequal in length to rami; peduncle and rami nacked. Uropod 2 ( Fig. 8 ) peduncle length subequal to rami with 1 apical robust seta on inner margin; inner ramus inner margin with 1 middle robust seta; outer ramus nacked. Uropod 3 ( Fig. 8 ) rami lanceolate longer than peduncle; outer ramus longer than inner ramus with 3 distal simple setae and 1 simple seta on outer margin; inner ramus with 1 robust seta on outer margin and 1 distal simple seta. Telson ( Fig. 8 ) cleft (0.7 X), each lobe blunt at apex, with 1 apical robust seta and 1apical plumose setae.

Remarks: Ampelisca minuta sp. nov. is similar to A. declivitatis Mills, 1967 , a small blind ampeliscid, for presenting antenna 1 of same length that the antenna 2 peduncle; pereopod 7 merus with a small anterior projection, propodus and dactylus of same length; uropod 3 with rami lanceolate, beyond absence of eyes. However, Ampelisca minuta sp. nov. can be differentiated from A. declivitatis for the anterior margin of the head truncated and ventral margin not oblique, whereas in A. declivitatis the ventral margin is clearly oblique; for the dorsal carina of urosome 1 not projected (in A. declivitatis urosome 1 presents an anterior acute projection); pereopod 7 basis with posterodistal margin oblique and not transverse as A. declivitatis and uropod 1 with peduncle and rami nacked, without robust setae.

Figures

FIGURE 7. Ampelisca minuta sp. nov., holotype female, 2 mm (MNRJ 20534). Scale bars = 0.1 mm.

FIGURE 8. Ampelisca minuta sp. nov., holotype female, 2 mm (MNRJ 20534). Scale bars = 0.1 mm.