Adeliella debroyeri Souza-Filho, Guedes-Silva & Andrade sp. n.

(Figures 1–5)

Material examined

Holotype female, 28 mm, Potiguar Basin, - 4.6113°S, 36.5248°W, Rio Grande do Norte state, Brazil, 2000 m depth, 4 May 2011, R / V Seward Johnson col. (MOUFPE 20192).

Type locality

Slope of Rio Grande do Norte state, north-eastern Brazil, 4.6113°S, 36.5248°W .

Diagnosis

Mandible lacinia mobilis present in both left and right; molar asymmetric, right large. Lower lip inner plate absent. Maxilla 2 inner plate subequal to outer plate. Maxilla 2 outer plate with 7 apical robust setae, gnathopod 1 carpus less than half of the propodus length; carpus subrectangular, palm almost transverse. Gnathopod 2 carpus lacking posterodistal lobe; propodus palm defined by 1 robust seta. Uropod 1 peduncle inflated proximally, almost 2.5× longer than outer ramus. Uropod 3 inner ramus half the length of outer ramus; outer ramus article 2 about 0.2× shorter than article 1. Telson ovate.

Description

Based on female holotype, 28 mm, MOUFPE 20192. Body as in Figure 1. Head (Figure 2a) short, lateral cephalic lobe broad and rounded, eyes absent. Antenna 1 (Figure 2b) stout and reduced; flagellum 11-articulate, article 1 with a dense row of callynophores; accessory flagellum 3-articulate. Antenna 2 (Figure 2c) weakly setose, articles 4–5 bearing dorsal setae; flagellum stout and short, 12-articulate. Upper lip (Figure 2d) rounded, naked. Lower lip (Figure 2e) naked. Mandibles (Figure 2f–g) right incisor with 3 blunt teeth; left incisor smooth with 2 short teeth; molar triturative; right lacinia mobilis distally broadened with 3 apical teeth; left lacinia mobilis as a single tapering peg; accessory setal row with 2 robust setae; palp 3-articulate, article 2 with distal facial setae, article 3 about 0.6× the length of article 2. Maxilla 1 (Figure 2h) inner plate with 1 short seta; outer plate with 8 robust setae; palp 2-articulate, article 2 broad, with 7 robust setae. Maxilla 2 (Figure 2i) plates thin and elongated; inner plate subequal to outer, with 4 apical setae; outer plate with 6 apical setae. Maxilliped (Figure 2j) inner plate apex with 6 setae; outer plate broad, tapering distally, with 14 short robust setae; palp article 4 about 0.3× the length of article 3, bearing an apical nail.

Coxa 1 (Figure 3a) slightly broadening distally. Coxa 4 (Figure 4b) posterodorsally excavated. Coxae 6–7 (Figure 4c–d) with strong posteroventral lobe. Gnathopod 1 (Figure 3a) basis anterior and posterior margin with short setae; propodus 1.4× longer than wide; palm almost transverse, defined by a robust seta inserted in an acute projection, margin with 7 humps varying from acute- to blunt-tipped; dactylus curved, almost reaching the palmar corner. Gnathopod 2 (Figure 3b) ischium elongated; carpus 1.8× longer than propodus; propodus 3.7× longer than wide anterior and posterior margins covered with setules; palm bearing a long robust seta near palmar corner, margin with a shallow concavity; dactylus short and curved, longer than palm. Pereopods 3–4 (Figure 4a–c similar in shape, weakly setose; merus longer than carpus; dactylus short. Pereopod 5 (Figure 4c) basis broad, slightly longer than wide, posterodistal corner produced as a lobe; merus posterodistal corner produced into a subacute lobe. Pereopods 6–7 (Figure 4d–e) basis about 1.5× longer than wide; basis–carpus anterior margin with sparse short robust setae.

Urosomite 1 (Figure 1) with a rounded carina. Epimera 1–3 (Figure 5a–c) naked, margins rounded. Uropod 1 (Figure 5d) peduncle elongated, 2.9× longer than wide, dorsal margin with a row of robust setae; rami lanceolate, with sparse robust setae bearing short apical nail; outer ramus slightly longer than inner. Uropod 2 (Figure 5e) peduncle 2.1× longer than wide; rami lanceolate, subequal, with marginal robust setae, bearing short apical nail. Uropod 3 (Figure 5f) peduncle 1.4× longer than wide; rami lanceolate; outer ramus 2-articulate, 1.8× longer than inner, article 2 about 0.2× the length of article 1; inner ramus with an apical short seta. Telson (Figure 5g) about 45% cleft, each lobe rounded with 1 short seta.

Etymology

The specific epithet is dedicated to Dr Claude De Broyer, for his great contribution to the taxonomy of amphipods and to the genus Adeliella .

Distribution and bathymetry

Known only from the type locality (slope of Rio Grande do Norte state, north-eastern Brazil, - 4,6113°S, - 36,5248°W), at 2000 m deep (Figure 23) .

Remarks

The new species described here can be distinguished from the other three species of the genus by the following: maxilla 1 inner plate bearing 7 robust setae; maxilla 2 inner plate subequal to outer plate; gnathopod 1 carpus 0.4× of propodus length, while the other species present maxilla 1 inner plate bearing 5 or 6 robust setae; maxilla 2 inner plate about half length of outer plate and gnathopod 1 carpus subequal to propodus.

Additionally, it closely resembles Ad. takoradia (J.L. Barnard 1961) in the gnathopod 2 carpus without a well-developed posterodistal and telson more than 40% cleft. However, Ad. debroyeri sp. n. differs from Ad. takoradia (characters in parenthesis) by having accessory flagellum shorter than article 1 of peduncle (longer than article 1); gnathopod 1 basis slender (moderately inflated), palm with blunt processes (subacute processes); and coxa 5 posterior lobe deeper than anterior (lobes subequal).

This is the first report of Adeliellidae and Adeliella from the South Atlantic Ocean and, consequently, from Brazilian waters.