Amaryllis atlantica, Senna, André R. & Serejo, Cristiana S., 2008

Senna, André R. & Serejo, Cristiana S., 2008, Amaryllididae and Lysianassidae (Amphipoda: Lysianassoidea) from off the central coast of Brazil (11 ºS – 22 ºS), with descriptions of three new species, Zootaxa 1718, pp. 45-68 : 47-51

Amaryllis atlantica sp. nov.

( Figures 1–3 )

Type material. Holotype: REVIZEE Benthos Program, Central SCORE, N/R Astro Garoupa col.: female, 14º56’49”S – 38º50’56”W, 45 m, October 21, 1997, MNRJ 19977.

Paratypes: REVIZEE Benthos Program, Central SCORE, N/R Astro Garoupa col.: four specimens, 16º47’10”S – 37º41’10”W, 50 m, June 30, 2001, MNRJ 17760; one specimen, 20º34’23”S – 38º03’32”W, 55 m, July 19, 2001, MNRJ 17769; one specimen, 18º39’47”S – 37º52’12”W, 65 m, June 29, 2001, MNRJ 17771; two specimens, 19º48’29”S – 37º56’20”W, 60 m, July 18, 2001, MNRJ 17778; three specimens, 19º31’38”S – 38º46’05”W, 65 m, June 28, 2001, MNRJ 19979; one specimen, 20º37’59”S – 40º01’30”W, 53.5 m, June 14, 2002, MNRJ 19978.

Diagnosis. Antenna 1, peduncle article 1 with distal margin without medial spine. Epistome slightly produced and convex; upper lip, anterior margin straight, tapering distally. Maxilla 1, outer plate with ST1-4 2- cuspidate; ST5 3-cuspidate; ST6 8-cuspidate; STA-B 2-cuspidate; STC 3-cuspidate; and STD 4-cuspidate. Left mandible, lacinia mobilis, laminar and distally cuspidate; molar small, setose; palp attached proximal to molar; palp of the maxilliped slightly surpassing the distal margin of the outer plate, article 2, inner margin with three distal setae, article 3, inner margin with seven distal setae, article 4 reduced, with two apical setae. Gnathopod 1, carpus 0.7X the length of the propodus. Pereopod 7, basis, posterior margin serrate and round, posterodistal margin rounded. Epimeral plate 3, posteroventral corner with a short and sharp projection below a notch.

Description. Holotype, female, length 6.7 mm. Head deeper than long; lateral cephalic lobe round; eyes reniform. Antenna 1 without setae, 0.75X the length of the antenna 2, article 1 of peduncle longer than broad, distal margin without medial spine; primary flagellum slightly elongate, with 8 articles; accessory flagellum reduced in four small and slender articles. Antenna 2, without setae; flagellum with 13 articles.

Mouthparts forming a subconical bundle. Epistome slightly produced and convex; upper lip, anterior margin straight, tapering distally. Maxilla 1, inner plate narrow, distal margin with two plumose setae; outer plate large, setal-teeth forming a distal crown in a 6/5 arrangement; ST1–4 2-cuspidate; ST5 3-cuspidate; ST6 8- cuspidate; STA-B 2-cuspidate; STC 3-cuspidate; and STD 4-cuspidate; palp absent. Left mandible, incisor smooth, margin convex, submarginal setae present; lacinia mobilis, laminar and distally cuspidate; molar small, setose; palp 3-articulate, attached proximal to molar; article 2 elongate, length 7X the width, smooth; article 3 suboval, minutely setose, with seven distoventral setae. Maxilliped, inner plate subquadrate; outer plate suboval, small, submarginal setae present, inner margin without setae, distal margin without setae; palp well developed, 4-articulate, slightly surpassing the outer plate, article 2, inner margin with three distal setae, article 3, inner margin with seven distal setae, article 4 reduced, with two apical setae.

Pereonites 1–7 dorsally smooth. Gnathopod 1 simple; coxa reduced, partially hidden by coxa 2, anterior and posterior margins subparallels; basis elongate, length 5X the width, anterior margin with a row of slender setae, anterodistal and posterodistal corners, each with a tuft of slender setae; ischium, slightly elongate, length 2X the width, posterodistal corner with a tuft of slender setae; merus subtriangular, posterodistal corner with a tuft of slender setae, carpus smaller than the propodus, 0.7X the propodus length, posterior margin setose; propodus distally tapering, posterior margin minutely setose, with tufts of slender setae, anterodistal corner with a tuft of setae; dactylus simple, curved, slightly elongate, with a single slender seta on the anterior margin, nail present. Gnathopod 2, coxa, anterior margin slightly concave, ventral margin with five small slender setae, distally bifid; basis elongate, length 6X the width; ischium slightly elongate; merus subtriangular; carpus, 1.3X longer than propodus, carpus and propodus subrectangular, anterior and posterior margins subparallels, posterior margin setose; propodus, anterodistal corner with a tuft of slender setae, palm slightly acute, with a lateral robust seta; dactylus simple, curved, reaching the palmar corner. Pereopod 3, coxa subequal in length to the coxa 2, with small slender setae on the ventral margin; carpus smaller than propodus; dactylus simple; oostegite present, elongate, without setae (probably lost). Pereopod 4, coxa posteroventrally expanded, anteroventral corner rounded, anterior and posterior margins subparallels. Pereopod 5, coxa posterolobated; basis posteriorly expanded, posteroventral margin rounded, smooth; merus posterodistally expanded; dactylus simple. Pereopod 6, coxa small, anterior margin straight, posterodistal margin slightly posterolobate; merus posterodistally expanded. Pereopod 7, coxa small; basis with posterior margin serrate and rounded, posterodistal margin rounded. Epimeral plate 3, posteroventral corner with a short and acute projection below an incision.

Pleonites 1–3 and urosomites 1–3 dorsally smooth. Uropod 1, peduncle with six dorsal and one dorsodistal stout setae; rami subequal in length. Uropod 2, outer ramus, 0.7X the inner ramus length, with four dorsal stout setae; inner ramus, with one dorsal seta, notch present. Uropod 3, rami lanceolate, without plumose setae; outer ramus 1-articulate. Telson, longer than broad, deeply cleft, half of its length, margin distally rounded, with an apical small slender seta on each lobe.

Remarks. Amaryllis was described initially by Haswell (1879) based on material from Australia, A. macrophthalma . More recently, Lowry & Stoddart (2002) revised the genus proposing a neotype for the species, as the type was lost. The selection of that neotype was based on the proximity of the original type-locality, given as "Tasmania", the posterior margin of the basis of pereopod 7 quadrate, and the great size of the species, approximately 20 mm. They propose a new diagnosis for the genus including all species with the outer ramus of uropod 3 1-articulate and that were restricted to Australia. The other citations of A. macrophthalma for other localities of the world, such as Patagonia ( Stebbing, 1888), Mauritius ( Ledoyer, 1978), Madagascar ( Ledoyer, 1979; 1986), Argentina ( Alonso, 1987) and Red Sea ( Lyons & Myers, 1991) with the outer ramus of uropod 3 2-articulate, were moved to the genus Erikus Lowry & Stoddart, 1987 .

The material examined in the present study fits with the diagnostic characters proposed by Lowry & Stoddart (2002) for the genus, and extends the distribution of Amaryllis to the Southwestern Atlantic Ocean. With this discovery, the hypothesis of endemism of Amaryllis to Australia is contested and suggest that the emergence of this genus relates to Gondwanian periods of formation of the South Atlantic Ocean, during the Mesozoic (Briggs, 1976).

Amaryllis atlantica sp. nov. is very similar to A. olinda in presenting an incision above the posteroventral corner of the epimeral plate 3, the basis of the pereopod 7 posteriorly rounded, the lacinia mobilis of the left mandible forming a narrow blade with several strong distal cusps and the distal margin of the article 1 of peduncle of the antenna 1 without medial spine. Amaryllis atlantica sp. nov. can be differentiated from this species by presenting the gnathopod 1 with carpus longer than propodus, the absence of setae in the second article of the mandibular palp and the absence of a facial incision on the anterior margin of the head.

Distribution. Amaryllis atlantica sp. nov. was collected in several localities off the coast of Bahia and Espírito Santo States, at depths varying from 40 to 65 m.

Etymology. The name atlantica refers to the discovery of a member of Amaryllis from the South Atlantic Ocean, contesting the hypothesis of endemism of this genus to the Australasian waters.

Figures

FIGURE 1. Amaryllis atlantica sp. nov., female 6.7 mm, 14 º 56 ’ 49 ” S – 38 º 50 ’ 56 ” W, 45 m, October 10, 1997, MNRJ 19977. Scale bars: 1.0 mm for habitus; 0.1 mm for the remainder.

FIGURE 2. Amaryllis atlantica sp. nov., female 6.7 mm, 14 º 56 ’ 49 ” S – 38 º 50 ’ 56 ” W, 45 m, October 10, 1997, MNRJ 19977. Scale bars: 0.1 mm for Gn 1; 0.5 mm for Gn 2; 0.2 mm for the remainder.

FIGURE 3. Amaryllis atlantica sp. nov., female 6.7 mm, 14 º 56 ’ 49 ” S – 38 º 50 ’ 56 ” W, 45 m, October 10, 1997, MNRJ 19977. Scale bars: 0.2 mm for P 6 – 7; 0.1 mm for the remainder.