Synopia ultramarina Dana, 1853

Senna, André R., Andrade, Luiz F., Guedes, Urssula N. & Pereira-Filho, Guilherme H., 2020, Redescription and new records of Synopia ultramarina Dana (Amphipoda: Synopiidae) from off the northeastern Brazil, with comments on its morphological variations, Iheringia, Série Zoologia (e 2020017) 110, pp. 1-11 : 3-8

Synopia ultramarina Dana, 1853

( Figs 2–29 )

Material examined. 1♀, dissected and drawn, September 2012, Fernando de Noronha Archipelago , Pernambuco state, Brazil, 03°49’2.51”S, 32°23’34.10”W, 12 m deep, rhodolith beds ( UERJ 542 ) ; 1♀, in 70% ethanol, same sampling data ( UFBA 2288 ) ; 1♀, dissected, same sampling data ( UFBA 2289 ) ; 1♀, in 70% ethanol, same sampling data ( UFBA 2292 ) ; 1♀, dissected and drawn, 1 January 2001, Petrobras 1 PEP 1 500J (2), Ceará state, Brazil, 03°07ʼ53.2ˮS, 38°49ʼ26.2ˮW, 36 m deep, soft bottom ( MOUFPE 19642 ) ; 1♀, dissected and drawn, 1 December 2000, REVIZEE NE IV #165, 6th campaign, Pernambuco state, Brazil, 8°08’06ˮS, 34°38’7.08ˮW, without depth data, bottom of bioclastic sand with granules and gravel ( MOUFPE 14566 ) .

Diagnosis. Head protuberant with anterior keel. Accessory eye with 2–3 ommatidia. Antenna 1, primary flagellum, article 1 callynophorate, remaining articles scarcely setose. Mandible palp, article 2 very stout, medial margin with row of setules and 1 long pappose seta. Right lacinia mobilis apically bifid. Left lacinia mobilis with 4 apical teeth. Maxilla 1 inner plate distally rounded. Maxilla 2 inner plate rounded, with medial row of long setae. Pereopods 5–6, basis with posteroventral corner rounded. Uropods 1–2, rami, margins setulose. Telson longer than wide, laterally smooth, with a slight acclivity or laterally serrate.

Description. Based on females, UERJ 542 and MOUFPE 19642 ( Fig. 2 ). Head ( Fig. 3 ) protuberant with anterior keel; rostrum short; accessory eyes with 2 ommatidia. Antenna 1 ( Fig. 4 ), peduncular article 1, anterior and posterior margins with 1 distal short seta each; article 2 anterior margin with 1 short seta distally, posterior margin with 2 short setae distally; article 3 naked; accessory flagellum 2-articulate; primary flagellum 5-articulate, article 1 with 8 callynophore. Antenna 2 ( Fig. 5 ), peduncular article 3 anterior margin produced distally with a short seta, posterior margin with 1 medial short seta; articles 4–5 weakly setose with few short setae; flagellum 9-articulate. Upper lip ( Fig. 7 ) rounded, apical margin with a small notch, setose. Right mandible ( Fig. 11 ), molar strongly triturative and with a group of setules basally, incisor with 4 teeth, lacinia mobilis apically bifid, accessory setal row with 2 multicuspidate and 2 apically bifid setae; palp ( Fig. 13 ) 3-articulate, article 1 short and subtriangular; article 2 very stout, about twice longer than wide, medial margin with row of setules and 1 pappose seta subdistally; article 3 very short, with 2 apical pappose setae. Left mandible ( Fig. 10 ), lacinia mobilis with 4 teeth. Lower lip ( Fig. 6 ), outer lobe laterally and apically setose, inner lobe apically setose. Maxilla 1 ( Fig. 8 ), inner plate with 3 long medial pappose setae and 1 short apical seta; outer plate medial margin with row of setules, apically with 6 stout setae; palp 2-articulate, article 2 lateral margin with row of long setules, apically with 4 multicuspidate stout setae and 2 short simple setae. Maxilla 2 ( Fig. 9 ), inner plate with distal field of setules, facial row of long setae present, medial and apical margins with row of long setae. Maxilliped ( Fig. 12 ), inner plate about 0.4× the length of outer plate, medial margin with 1 plumose seta, apically with 2 slender and 1 stout plumose seta; outer plate about 0.8× the length of palp articles 1 and 2 combined, medial margin with 3 plumose setae, apical and lateral margins with 1 long plumose seta each; palp 4-articulate, article 2 with a row of 9 long plumose setae on the medial margin; article 3 with two pairs of subapical plumose setae; article 4 short, bearing a long apical slender seta.

Pereon. Gnathopod 1 ( Fig. 14 ) simple; coxa short, about 0.7× the length of coxa 2, with 2 posterodistal short setae; basis about 3.5× longer than wide, anterior margin with 2 long setae on a distal lobe, posterodistal corner with 1 seta; ischium short and subquadrate, posterodistal corner with 1 long pappose seta; merus posterior margin with 3 pappose setae; carpus twice longer than wide, anterior margin with 2 long pappose setae distally, posterior margin setose, with a row of long plumose setae; propodus ovate, about 1.6× longer than wide, anterior margin with 2 pappose setae distally, posterior margin setose with row of long plumose setae; palm acute; dactylus about 80% the length of propodus, nail elongate. Gnathopod 2 ( Fig. 15 ) simple; coxa small, postero ventral margin with 2 setae; basis about 5.2× longer than wide, posterior margin with 2 long setae; ischium short and subrectangular, posterodistal corner with 1 seta; merus posterior margin with 2 short setae; carpus 3.8× longer than wide, posterior margin setose, with a row of long pappose setae; propodus 4.7× longer than wide, anterior margin with 1 long pappose seta distally, posterior margin setose, with a row of long pappose setae plus 2 longer pappose setae distally; dactylus vestigial, nail present. Pereopod 3 ( Fig. 16 ), coxa with posterior lobe subquadrate and produced, posterodorsal margin excavate, ventral margin convex; basis 4.2× longer than wide, posterior margin with 3 setae, posteroventral corner with 1 seta; ischium short and subrectangular, posterior margin with 3 setae; merus1.5× longer than wide, anterior margin with 1 long plumose seta distally, posterior margin with 3 plumose setae; carpus 1.9× longer than wide, posterior margin setose, with a row of plumose setae; propodus posterior margin setose, with a row of plumose setae plus 1 longer plumose seta distally; dactylus about 50% the length of propodus, nail present. Pereopod 4 ( Fig. 17 ), coxa subtriangular, postero distal lobe produced; basis 4.5× longer than wide, anterior margin with 3 long setae, posterodistal corner with 1 long seta; ischium short and subrectangular, posterodistal corner with 1 seta; merus 2.2× longer than wide, anterodistal margin produced, with 1 long plumose seta, posterior margin with 3 plumose setae; carpus twice longer than wide, posterior margin setose with a row of plumose setae;propodus 2.2× longer than wide, posterior margin setose, with a row of plumose setae; dactylus about 60% the length of propodus, nail present. Pereopod 5 ( Fig. 18 ), coxa subtriangular and smooth; basis 1.2× longer than wide, suboval, posteroventral corner rounded; ischium short and subquadrate; merus anterior margin with 2 medial and 1 distal stout seta, posterior margin with 1 stout seta distally; carpus anterior margin with 1 medial and 2 distal stout setae, posterior margin with 1 stout seta distally; propodus 8.7× longer than wide, anterior margin with 1 medial and 2 distal stout setae, posterior margin with 1 medial and 1 distal stout seta; dactylus elongate, about 90% the length of propodus. Pereopod 6 ( Fig. 19 ), coxa subrectangular, posteroventral lobe weakly produced; basis 1.4× longer than wide, suboval, posteroventral corner rounded; ischium short and subrectangular; merus anterior and posterior margins with 1 stout seta distally; carpus anterior margin with 1 stout seta distally, posterior margin with 2 stout setae distally; propodus 8.4× longer than wide, anterior margin with 1 medial and 1 distal stout seta, posterior margin with 1 medial stout seta; dactylus elongate, about 60% the length of propodus. Pereopod 7 ( Fig. 20 ), coxa subrectangular, posteroventral corner weakly produced; basis 1.8× longer than wide, anterodistal corner with 1 short seta, posterodistal lobe well developed, subacute, almost reaching half of merus; ischium short and subrectangular; merus anterior and posterior margins with 1 stout seta distally; carpus, anterior margin with 1 medial and 2 distal stout setae, posterior margin with 1 distal stout seta; propodus 6× longer than wide, anterior margin with 3 medial and 2 distal stout setae, posterior margin with 2 distal stout setae; dactylus stout, about 60% the length of propodus.

Pleon. Epimeral plate 1 ( Fig. 21 ), anterior margin slightly concave, ventral margin naked, posteroventral corner rounded, posterior margin convex. Epimeral plate 2 ( Fig. 22 ), anterior margin convex, ventral margin naked, posteroventral corner slightly produced into a subacute angle; Epimeral plate 3 ( Fig. 23 ), anterior margin convex, ventral margin naked, posteroventral corner subquadrate, posterior margin almost straight. Urosomite 1, anterodistal margin produced intoan acute tooth, with a weak sinuosity above. Uropod 1 ( Fig. 24 ), peduncle 3.3× longer than wide,dorsal margin with 2 stout setae medially and 1 apically; outer ramus dorsolaterally setulose, apical margin with 3 stout setae; inner ramus 1.4× longer than outer ramus, ventrolaterally setulose, dorsal margin with 1 stout seta medially and 4 apically. Uropod 2 ( Fig. 25 ), peduncle 2.6× longer than wide, dorsal margin with 1 stout seta medially and 1 apically; outer ramus slightly shorter than inner, dorsolaterally setulose, apical margin with 2 stout setae; inner ramus 1.2× longer than outer, ventrolaterally setulose, dorsal margin with 1 stout seta, bearing 2 setae apically. Uropod 3 ( Fig. 26 ), peduncle short, slightly longer than wide, ventroapical margin with 1 stout seta; outer ramus slightly longer than inner, 2-articulate, article 1 with 2 setae dorsolaterally, article 2 about 30% the length of article 1, apical margin with 3 setae; inner ramus, ventrolateral margin with a proximal row of setules and 5 setae, apical margin with 2 setae. Telson ( Figs. 27-29 ) 1.6× longer than wide, about 70% cleft, longer than peduncle of uropod 3, each lobe with 2 lateral setae, distalmost placed on a slight acclivity, and one long apical seta.

Figures

Fig. 2. Synopia ultramarina Dana, 1853, habitus (MOUFPE 19642). Scale bar: 1.0 mm.

Figs. 3–13. Synopia ultramarina Dana, 1853: 3, head; 4, 5, antennae 1–2; 6, lower lip; 7, upper lip; 8, 9, maxillae 1–2; 10, 11, left and right mandibles; 12, maxilliped (UERJ 542); 13, palp of mandible (MOUFPE 19642). Scale bars: 0.2 mm for Figs 4, 5; 0.1 mm for the remains.

Figs. 14–17. Synopia ultramarina Dana, 1853: 14, 15, gnathopods 1–2; 16, 17, pereopods 3–4 (MOUFPE 19642). Scale bars: 0.3 mm.

Figs. 18–23. Synopia ultramarina Dana, 1853: 18–20, pereopods 5–7; 21–23, epimeral plates 1–3 (UERJ 542). Scale bars: 0.2 mm.

Figs. 24–29. Synopia ultramarina Dana, 1853: 24–26, uropods 1–3; 28, telson (MOUFPE 19642); 27, telson (UERJ 542); 29, telson (MOUFPE 14566). Scale bars: 0.3 mm for Figs 24, 25; 0.1 for Fig. 27; 0.2 mm for the remains.