Metharpinia dentiurosoma Alonso de Pina, 2003

Andrade, Luiz F. & Senna, André R., 2020, New and additional records of Metharpinia Schellenberg, 1931 and Microphoxus Barnard, 1960 (Crustacea: Amphipoda: Phoxocephalidae) from Brazilian waters, Papéis Avulsos de Zoologia 60, pp. 1-37 : 2-9

Metharpinia dentiurosoma Alonso de Pina, 2003 ( Figs. 1‑6 )

Metharpinia dentiurosoma Alonso de Pina, 2003b: 2523 , figs. 1‑7. López‑Gappa et al., 2006: 16, 52. Alonso & Chiesa, 2014: 206, 207, 209, fig. 3C, E‑I. Andrade et al.,

2015: 39. Material examined: 6 ♀♀, in 70% ethanol, MBT 155,

22°22′S, 41°32′W, 34 m depth, Rio de Janeiro state, 05 September 1970 ( UERJ 412 ) ; 7 ♀♀, in 70% ethanol, MBT 155, 22°22′S, 41°32′W, 34 m depth, Rio de Janeiro state, 05 September 1970 ( MZUSP 41105 ) ; 1 ♀, in 70% ethanol, MBT 217, 23°00′S, 42°41′W, 45 m depth, Rio de Janeiro state, 05 June 1971 ( UERJ 410 ) ; 4 ♀♀, in 70% ethanol, MBT 217, 23°00′S, 42°41′W, 45 m depth, Rio de Janeiro state, 05 June 1971 ( UERJ 413 ) ; 4 ♀♀, in 70% ethanol, MBT 217, 23°00′S, 42°41′W, 45 m depth, Rio de Janeiro state, 05 June 1971 ( MZUSP 41104 ) ; 1 ♀ and 1 ♂, in 70% ethanol, MBT 140, 23°02′S, 43°00′W, 40 m depth, Rio de Janeiro state, 02 September 1970 ( UERJ 416 ) ; 1 ♀, in 70% ethanol, MBT 206, 23°14′S, 44°03′W, 52 m depth, Rio de Janeiro state, 03 June 1971 ( UERJ 417 ) ; 4 ♀♀, in 70% ethanol, MBT 50, 23°39′S, 45°06′W, 28 m depth, São Paulo state, 08 May 1970 ( UERJ 415 ) ; 1 ♀, dissected and drawn, MBT 81, 24°46′S, 45°58′W, 72 m depth, São Paulo state, 16 June 1970 ( UERJ 409 ) ; 1 ♂, dissected and drawn, MBT 81, 24°46′S, 45°58′W, 72 m depth, São Paulo state, 16 June 1970 ( UERJ 411 ) ; 6 ♀♀, in 70% ethanol, MBT 81, 24°46′S, 45°58′W, 72 m depth, São Paulo state, 16 June 1970 ( UERJ 414 ) ; 1 ♀, in 70% ethanol, MBT 129, 29°13′S, 49°25′W, 27 m depth, Santa Catarina state, 25 June 1970 ( UERJ 418 ) .

Diagnosis: Head, eyes rounded and medium‑sized; rostrum constricted, narrow, elongate and spatulate. Antenna 1, peduncle article 2 elongate. Antenna 2, peduncle article 4, with 4 rows of facial stout setae. Mandible molar as a small hump with stout setae, left lacinia mobilis flabellate, right lacinia mobilis bifid. Maxilla 1, inner plate with 4 plumose setae; palp 2‑articulate. Maxilliped, inner plate with 2 stout setae apically; palp, article 4 narrow, with medium apical nail, partially embedded. Gnathopods 1‑2, anterior margin weakly setose; palm acute, palmar hump large. Pereopod 7, basis, expanded posteroventrally, reaching apex of carpus. Epimeral plate 3, posterior margin weakly crenulate, posteroventral corner strongly produced into a large tooth. Urosomite 3, produced as a large acute hook dorsally. Uropods 1‑2, peduncle, apicolateral corner serrate, rami with stout setae pointing upwards. Uropod 3, outer ramus longer than inner, article 2 elongate, with 2 apical setae. Telson, deeply cleft, apex truncate, with variable stout and simple setae on each side.

Description: Based on female (UERJ 409). Habitus as in Fig. 1 . Head ( Fig. 2A, B ) eyes rounded and medium‑sized; rostrum constricted, narrow, elongate and spatulate. Antenna 1 ( Fig. 2C ), peduncle article 1, about 1.5× longer than wide, ventral margin with brush setae, dorsal apex with 2 setae; article 2, ventral margin with a tuft of long setae; article 3, short, ventral margin with 3 setae; primary flagellum 12‑articulate; accessory flagellum 8‑articulate. Antenna 2 ( Fig. 2D ), peduncle article 4, facial stout setae formula: 1‑3‑5‑4, ventral margin with brush setae and few simple with 1 stout seta distally; article 5, ventral margin with long and brush setae, facial margin with 5 stout setae medially and 3 stout setae distally; flagellum 14‑articulate. Lower lip ( Fig. 2J ), outer lobes with setules apically. Left and right mandibles ( Fig. 2I, H ), left molar forming a small hump with 8 stout setae, right molar with 7 stout setae, left incisor with 2 weak teeth, right incisor with 3 teeth, left lacinia mobilis flabellate, right lacinia mobilis bifid, accessory setal rows with 13 stout setae; palp 3‑articulate, article 1 short, article 2 with 8 setae, article 3 slightly longer than article 2, with 3 setae, apex oblique, with 9 medium to long setae. Maxilla 1 ( Fig. 2E ), inner plate with 4 plumose setae; out‑ er plate with 10 multicuspidate stout setae; palp 2‑articulate, article 2 with 6 plumose and 3 stout setae. Maxilla 2 ( Fig. 2F ), inner plate with long setules and plumose setae; outer plate slightly longer than inner, setose apically. Maxilliped ( Fig. 2G ), inner plate with 7 plumose and 2 stout setae apically; outer plate with 2 slender and 7 stout setae; palp, article 1, with 1 apicolateral seta, article 2 with 2 setae laterally, medial margin moderately setose, article 3 moderately setose, article 4 narrow, with 1 medium apical nail, partially embedded.

Gnathopod 1 ( Fig. 3A ), coxa, subrectangular, ventral margin with 11 setae; basis, margins with short to long setae; ischium, small and subrectangular; merus, posteri‑ or margin weakly setose; carpus, anterior margin with 2 setae distally, posterior margin weakly setose; propodus, weakly setose, anterior margin with a tuft of setae distally, posterior margin with 1 stout seta defining palm; palm acute, with setules, palmar hump large; dactylus, slightly longer than palm. Gnathopod 2 ( Fig. 3B ), coxa, subrectangular, ventral margin with 17 setae; basis, margins with short to long setae; ischium, small and subrectangular, posterior margin with 1 seta; merus, posterior margin with a tuft of setae; carpus, anterior margin with 1 seta distally, posterior margin weakly setose; propodus, weakly setose, anterior margin with a tuft of setae distally, posterior margin with 1 stout seta defining palm; palm acute, with setules, palmar hump large; dactylus slightly longer than palm. Pereopod 3 ( Fig. 3C ), coxa, subrectangular, ventral margin with 11 setae; basis, anterior and posterior margins with short to medium setae; ischium, small and subrectangular, posterior margin with 2 setae; merus, anterior margin with 1 long seta, posterior margin weakly setose, facial margin with row of 4 setae distally; carpus, posterior margin weakly setose, with 1 subdistal thicker stout seta extending 65% of propodus; propodus, posterior margin with 7 stout setae; dactylus, about 55% the length of propodus. Pereopod 4 ( Fig. 3D ), coxa, subtriangular, ventral margin with 18 short setae, posterodorsal margin weakly excavate; remaining articles are very similar to pereopod 3, differing only by some arrangements of setae. Pereopod 5 ( Fig. 4A ), coxa bilobate; basis subrectangular and thickening distally, anterior margin with short to long setae, posterior margin naked; ischium, small and subrectangular, anterior margin with row of 6 setae extending to facial margin; merus, margins weakly setose, facial margin with 5 rows of stout setae: 4‑3‑3‑6‑8; carpus, margins weakly setose, facial margin with 5 rows of stout setae:2‑2‑2‑3‑7; propodus, margins weakly setose, anterior margin with 6 stout setae, posterior margin with 4 stout setae distally; dactylus, about 60% the length of propodus. Pereopod 6 ( Fig. 4B ), coxa, posterior margin with row of short setae; basis, anterior margin with short to long setae; ischium, small and subrectangular, anterior margin with 3 setae; merus, margins weakly setose, facial margin with 4 rows of stout setae: 5‑3‑7‑5; carpus, facial margin with 4 rows of stout setae: 4‑5‑6‑4; propodus, margins weakly setose, anterior margin with 6 stout setae, posterior margin with 7 stout setae; dactylus, about 40% the length of propodus. Pereopod 7 ( Fig. 4C ), coxa, subtriangular, posterior margin with short setae; basis, about 1.2× longer than wide, strongly expanded posteroventrally, reaching apex of carpus, anterodistal corner with 1 stout seta, posterior margin serrate,with setules;ischium,small and subquadrate, anterior margin with 2 stout setae; merus, anterior margin with 7 stout setae, posterior margin with 1 stout seta distally; carpus, anterior margin with 7 stout setae, posterior margin with 4 stout setae distally; propodus, anterior margin with 6 stout setae, posterior margin with 7 stout setae; dacytlus, with accessory seta, about 65% the length of propodus.

Epimeral plate 1 ( Fig. 5A ), anterior margin rounded, anteroventral corner with 2 setae, posteroventral corner with a small rounded hump, bearing 2 long setae, posterior margin convex, with 2 short setae. Epimeral plate 2 ( Fig. 5B ), anterior margin weakly concave, with 2 setae, ventral margin with 5 plumose setae, posteroventral corner with a small subacute hump, posterior margin rounded, with 3 setae. Epimeral plate 3 ( Fig. 5C ), anterior margin rounded, with 3 plumose setae, posteroventral corner strongly produced into a large tooth, posterior margin weakly crenulate, with 4 setae, facial margin with an oblique row of 10 stout setae extending from posteroventral margin to middle of plate, decreasing in length. Urosomite 3, produced as a large acute hook dorsally. Uropod 1 ( Fig. 5D ), peduncle, about 2.5× longer than wide, dorsomedial margin with 5 stout setae, dorsolateral margin with 11 stout setae, apicolateral corner microscopically combed; outer ramus, slightly longer than inner, dorsal margin with 9 stout setae, bearing 1 subapical nail; inner ramus, dorsal margin with 5 stout setae, bearing 1 subapical nail. Uropod 2 ( Fig. 5E ), peduncle 2× longer than wide, dorsomedial margin with 10 stout setae, apicolateral corner microscopically combed; outer ramus, slightly longer than inner, dorsal margin with 5 stout setae, bearing 1 subapical nail; inner ramus, dorsal margin with 3 stout setae, bearing 1 subapical nail. Uropod 3 ( Fig. 5F ), peduncle, about 1.6× longer than wide, dorsal margin with 1 stout seta and 1 setule, ventral margin with 5 stout setae apically; outer ramus, article 1, ventral margin with 7 stout setae,article 2, elon‑ gate, with 2 setae apically; inner ramus, about 55% the length of outer, naked. Telson ( Fig. 5G ), about 85% cleft, apex subtruncate, with 1 plumose and 2 stout setae apically, lateral margins with 2 setae on each side.

Sexual dimorphism: Based on male (UERJ 411). Body, smaller in size. Eyes, larger and more pigmented.

Antenna 1 ( Fig. 6B ), peduncle article 1, 1.4× longer than wide, ventral margin with a tuft of setules and 3 brush setae distally,dorsal apex with 1 brush seta;article 2, ventral margin with 3 plumose setae medially and 4 setae distally; article 3, short, dorsal margin with 2 short and 2 brush setae; primary flagellum 10‑articulate, with calceoli on articles 2‑4; accessory flagellum 8‑articulate. Antenna 2 ( Fig. 6A ), peduncle article 3, short, facial margin with 1 long seta, dorsal margin with a tuft of setules distally; article 4, facial stout setae formula: 1‑2‑4‑3, ventral margin with 4 brush setae proximally, facial and ventral margin with long setae and 1 stout seta distally, dorsal margin covered with setules; article 5, facial margin with 3 stout setae and few brush setae, ventral margin with short to long setae and 4 brush setae, dorsal margin with tufts of setules; flagellum 32‑articulate, with 11 calceoli.

Gnathopods 1‑2 ( Fig. 6C, D ), similar in size, but more robust than in female.

Uropod 3 ( Fig. 6E ), peduncle, about 1.4× longer than wide, ventral margin with 5 stout setae distally, dorsal margin with 1 stout seta distally, lateral margin with a hump with 1 stout seta apically; outer ramus, article 1, ventral margin with 1 long plumose seta distally and two acclivities, stout setae formula: 1‑2‑1, dorsal margin with 7 long plumose setae, article 2, elongate, with 2 long plumose setae apically; inner ramus,slightly shorter than outer, dorsal margin covered with long plumose setae, apical margin with 2 long plumose setae.

Type locality: Argentine Sea, El Rincón, Buenos Aires, Argentina (39°49′58″S, 61°35′02″W).

Remarks: Metharpinia dentiurosoma was described with material from Buenos Aires ( Argentina) and this is the first record of the species for Brazilian waters. Due to characteristics of antennae, mandibles, gnathopods and uropods, this species seems to be morphologically close to Mi. uroserratus described for Sepetiba Bay, Rio de Janeiro state, Brazil (22°58′S, 44°02′W). However, it can be distinguished by the latter by presenting: head with a visible acute dorsolateral projection, rostrum slightly exceeding apex of first article of antenna 1; epimeral plate 3 posteroventral corner strongly produced into a large tooth and facial margin with an oblique row of stout setae.

Geographic distribution: Argentina: Argentine Sea; Brazil (this report): coast of the states of Rio de Janeiro, São Paulo and Santa Catarina.

Bathymetric range: 14‑72 m depth.

Figures

Figure 1. Metharpinia dentiurosomaAlonso de Pina,2003,female (UERJ 409):Habitus.Scale bar: 1.5mm.

Figure 2. Metharpinia dentiurosoma Alonso de Pina,2003,female (UERJ 409): (A) Head in lateral view; (B) Head in dorsal view; (C) Right antenna 1; (D) Right antenna 2;(E)Left maxilla 1; (F) Left maxilla 2; (G) Left maxilliped;(H) Right mandible;(I) Left mandible;(J) Lower lip.Scale bars:0.5mm for A-B;0.2 mm for C-D,H-I; 0.1 mm for the remaining.

Figure 3. Metharpinia dentiurosoma Alonso de Pina, 2003, female (UERJ 409): (A) Right gnathopod 1; (B) Right gnathopod 2; (C) Right pereopod 3; (D) Right pereopod 4. Scale bars:0.3mm.

Figure 4. Metharpiniadentiurosoma Alonsode Pina,2003,female(UERJ 409):(A) Right pereopod 5;(B) Right pereopod 6;(C) Right pereopod 7. Scale bars:0.2mm for C;0.5for the remaining.

Figure 5. Metharpinia dentiurosoma Alonso de Pina, 2003, female (UERJ 409): (A) Right epimeral plate 1; (B) Right epimeral plate 2; (C) Right epimeral plate 3; (D) Right uropod 1; (E) Right uropod 2; (F) Right uropod 3; (G) Telson.Scale bars:0.5 mm for A-C;0.2 mm for the remaining.

Figure 6.MetharpiniadentiurosomaAlonsode Pina,2003,male(UERJ 411):(A)Right antenna 2; (B) Rightantenna 1; (C)Right gnathopod 1; (D)Right gnathopod 2; (E) Right uropod 3. Scale bars:0.2 mm.