Metharpinia grandirama 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 : 9-15

Metharpinia grandirama Alonso de Pina, 2003 ( Figs. 7‑11 )

Metharpinia grandirama Alonso de Pina, 2003b: 2533 , figs. 8‑15. López‑Gappa et al., 2006: 16, 52. Alonso & Chiesa, 2014: 206, 207, 209, fig. 3J‑N. Andrade et al.,

2015: 39. Material examined: 1 ♀, in 70% ethanol, MBT 217,

23°00′S, 42°41′W, 45 m depth, Rio de Janeiro state, 05 June 1971 ( UERJ 421 ) ; 1 ♀, in 70% ethanol, MBT 90, 24°36′S, 47°07′W, 21 m depth, São Paulo state, 17 June 1970 ( UERJ 422 ) ; 1 ♀, dissected and drawn, MBT 81, 24°46′S, 45°58′W, 72 m depth, São Paulo state, 16 June 1970 ( UERJ 419 ) ; 1 ♀, in 70% ethanol, MBT 172, 25°21′S, 47°30′W, 37 m depth, São Paulo state, 27 May 1971 ( MZUSP 41106 ) .

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, lacinia mobilis flabellate; palp, article 3 longer than article 2. Maxilla 1, inner plate with 4 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, almost reaching apex of carpus. Epimeral plate 3, posteroventral corner rounded. Urosomite 3, produced as a large acute hook dorsally. Uropod 1, inner ramus, dorsal margin with 1 stout seta and 1 subapical nail. Uropod 2, short and stout; inner ramus short, with 1 subapical nail. Telson, deeply cleft, apex rounded, lateral margin with shallow acclivity, each lobe with 1 stout and variable simple and plumose setae.

Description: Based on female (UERJ 419). Habitus as in Fig. 7 . Head ( Fig. 8A,B ), eyes rounded and medium‑sized; rostrum constricted, narrow, elongate and spatulate. Antenna 1 ( Fig. 8C ), peduncle article 1, about 1.4× longer than wide, ventral margin with 2 brush setae, dorsal apex with 1 seta; article 2, ventral margin with a tuft of plumose setae; article 3, short, ventral margin with 1 setule; primary flagellum 14‑articulate; accessory flagellum 12‑articulate. Antenna 2 ( Fig. 8D ), peduncle article 4, facial stout setae formula: 1‑3‑5‑5, ventral margin with medium to long plumose setae; dorsal margin with 1 stout and 1 plumose seta proximally; article 5, ventral margin with medium to long plumose setae, facial margin with row of 4 stout setae; flagellum 17‑articulate. Left mandible ( Fig. 8H ), molar as a small hump with 5 stout setae, incisor with 2 weak teeth and hump, lacinia mobilis flabellate, with 5 teeth, accessory setal row with 8 stout setae, palpar hump small; palp 3‑articulate, article 1 short, article 2 with 2 setae, article 3 longer than article 2, apex oblique, with 9 medium to long setae. Right mandible ( Fig. 8I ), molar as a small hump with 6 stout setae, lacinia mobilis flabellate,incisor with 3 weak teeth,accessory setal setal row with 8 stout setae, palpar hump small; palp 3‑articulate, article 1 short, article 2 with 2 setae, article 3 longer than article 2, apex oblique, with 11 medium to long setae. Maxilla 1 ( Fig. 8F ), inner plate with 4 setae; outer plate with with 9 multicuspidate stout setae; palp 2‑articulate, article 2 with 4 simple setae and 3 pectinate stout setae apically. Maxilla 2 ( Fig. 8E ), inner plate, about 70% the length of outer, medial margin covered with setules, apical and subapical margins with simple and stout setae; outer plate, apical margin with plumose setae, lateral margin covered with setules. Maxilliped ( Fig. 8G ), inner plate with 6 plumose setae and 2 stout setae apically; outer plate with 7 bipectinate stout setae; palp, article 1 with 1 apicolateral seta, article 2, medial margin moderately setose, lateral margin with 5 long setae, article 3, margins weakly setose, article 4, narrow, with accessory setule and 1 medium apical nail partially embedded, shorter than in M. dentiurosoma .

Gnathopod 1 ( Fig. 9A ), coxa, weakly expanded anteriorly, posterior margin weakly concave, ventral margin with 15 setae; basis, anterior and posterior margins with medium to long plumose setae; ischium, small and subrectangular, posterior margin with 4 long plumose setae; merus, posterior margin with 4 long plumose setae; carpus, anterior margin with 1 plumose seta distally, posterior margin moderately setose, facial margin with 4 long plumose setae; propodus, weakly setose, anteri‑ or margin with a tuft of setae, posterior margin with 1 stout seta defining palm; palm acute, with setules, palmar hump large; dactylus reaching the palmar corner. Gnathopod 2 ( Fig. 9B ), coxa, subrectangular, posterior margin weakly concave, ventral margin with 14 setae; basis, anterior and posterior margins with long plumose setae; ischium, small and subrectangular, posterodistal corner with 4 long plumose setae; merus, posterior margin with 3 short setae distally; carpus, anterior margin with row of 4 setae, posterior margin moderately setose; propodus, weakly setose, anterior margin with a tuft of setae, posterior margin with 1 stout seta defining palm; palm acute, with setules, palmar hump large; dactylus, reaching the palmar corner. Pereopod 3 ( Fig. 9C ), coxa subrectangular, proportionally shorter than in M. dentiurosoma , ventral margin with 17 setae; basis, posterior margin with medium to long setae; ischium, small and subrectangular, posterodistal corner with 4 short setae; merus, anterior margin with 1 seta distally, posteri‑ or margin moderately setose; carpus, posterior margin weakly setose, with 1 subdistal thicker stout setae extending 75% of propodus; propodus, anterior margin with 1 short plumose seta distally, posterior margin with 11 stout setae; dactylus, about 50% the length or propodus. Pereopod 4 ( Fig. 9D ), coxa, posteroventral margin setose; remaining articles are very similar to pereopod 3, differing only by some arrangements of setae. Pereopod 5 ( Fig. 10A ), coxa,bilobate, posteroventral margin with 13 setae; basis subrectangular and thickening distally, anterior margin weakly setose, anterodistal corner with 3 setae and row of 6 setae extending to facial margin; ischium, small and subrectangular, anterodistal corner with row of 6 setae; merus, anterior and posterior margins setose, facial stout setae formula: 6‑5‑6‑4‑6; carpus more robust than in M. dentiurosoma , anterior and posterior margins moderately setose, facial stout setae formula: 3‑8‑5‑7‑6; propodus,anterior and posterior margins moderately setose, anterior margin with 7 stout setae, posterior margin with 2 stout setae; dactylus, about 45% the length of propodus. Pereopod 6 ( Fig. 10B ), coxa, posterior margin with 3 setae; basis weakly setose, posterior margin more straight than in M. dentiurosoma anterodistal corner with a tuft of setae; ischium, small and subrectangular, anterodistal corner with a row of 6 setae; merus, anterior margin with long and stout setae, posterior margin with long bipectinate and stout setae, facial stout setae formula: 4‑6‑5‑8; carpus, posterior margin with long setae, facial stout setae formula: 8‑4‑6‑3; propodus, posterior margin with long setae, facial stout setae formula: 3‑2‑3‑2‑3; dactylus, short, about 20% the length of propodus. Pereopod 7 ( Fig. 10C ), coxa, subrectangular, posterior margin with 9 setae; basis, 1.5× longer than wide, expanded posteroventrally, reaching half of carpus, posterior margin weakly crenulate,anterodistal corner with 1 seta;ischium,small and subquadrate, anterior margin with 2 setae; merus, anterior and posterior margins with 4 setae; carpus, anterior margin with 8 setae, posterior margin with row of 4 setae distally; propodus, anterior and posterior margins weakly setose; dactylus, about 70% the length of propodus.

Epimeral plate 1 ( Fig. 11A ), anterior margin with 4 setae, ventral margin with 8 plumose setae, posterior margin convex, weakly serrate, with 5 setae. Epimeral plate 2 ( Fig. 11B ), anterior margin produced and round‑ ed, ventral margin with 8 plumose setae, posterior margin weakly crenulate, with 3 setae. Epimeral plate 3 ( Fig. 11C ), anterior margin produced and rounded, pos‑ teroventral corner rounded, posterior margin weakly crenulate, with 3 setae, facial margin with 1 short seta. Urosomite 1, ventral margin with a proximal tuft of se‑ tae. Urosomite 3, produced as a large acute hook dorsally. Uropod 1 ( Fig. 11D ), peduncle, about 1.7× longer than wide, dorsomedial margin with 2 long and 1 short stout

seta, dorsomedial corner with 1 thicker stout seta, dorsolateral corner with 1 stout seta; rami shorter than peduncle; outer ramus,slightly longer than inner, dorsal margin with 5 stout setae bearing 1 subapical nail; inner ramus, dorsal margin with 1 stout seta, bearing 1 subapical nail. Uropod 2 ( Fig. 11E ), short and stout, peduncle, about 1.4× longer than wide, dorsolateral margin with 6 stout setae, being the apical‑most much stouter; rami shorter than peduncle; outer ramus, 1.6× longer than inner, dorsal margin with 4 stout setae, bearing 1 subapical nail; inner ramus, short, bearing 1 subapical nail. Uropod 3 ( Fig. 11F ), peduncle, about 2× longer than wide, ventral margin with 3 stout setae, dorsal margin with 1 stout seta; outer ramus, slightly longer than inner, article 1, ventral margin with 2 acclivities, stout setae formula: 2‑2‑2, dorsal margin with 3 setae distally, article 2, short, with 1 short and 2 long setae apically;inner ramus, with 1 apical and 1 subapical seta. Telson ( Fig. 11G ), about 80% cleft, apex rounded on the inner part, with shallow lateral acclivity, with 1 short stout and 2 plumose setae on each side, dorsolateral margin with 1 plumose and 3 long setae on each side.

Type locality: Argentine Sea, El Rincón, Buenos Aires, Argentina (39°05′36″S, 61°20′11″W).

Remarks: Metharpinia grandirama 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, gnathopods and especially the shape of uropods 1‑2, this species seems to be morphologically very close to Mi. breviramus , described for Arraial do Cabo, Rio de Janeiro state, Brazil (23°03′S, 42°02′W), with both presenting rami of uropods 1‑2 much shorter than the other species of their respective genus. However, M. grandirama can be distinguished by the latter by subtle characteristics like: head with a visible dorsolateral projection; pereopod 7, basis not so expanded posteriorly; setal distribution on epimeral plates 1‑3; and number of stout setae on uropods 1‑2. Even if morphological variations are reported for different individuals of both species, due to the strong similarities on their uropods, a new analysis of the type material used for the original descriptions is necessary in order to confirm if both species are valid or if they should be synonymized.

Geographic distribution: Argentina: Argentine Sea; Brazil: coast of the states of Rio de Janeiro and São Paulo.

Bathymetric range: 9‑72 m depth.

Figures

Figure 7. Metharpiniagrandirama Alonso de Pina,2003,female (UERJ 419): Habitus.Scale bar:2.5 mm.

Figure8.MetharpiniagrandiramaAlonso dePina,2003,female(UERJ419):(A) Headinlateralview;(B)Headindorsalview;(C)Right antenna1;(D)Right antenna2; (E) Left maxilla 2; (F) Left maxilla 1; (G) Left maxilliped;(H) Left mandible;(I) Right mandible.Scale bars:0.5 mm for A-D;0.1 mm for E;0.2 mm for the remaining.

Figure 9. Metharpinia grandirama Alonso de Pina, 2003,female (UERJ 419): (A) Right gnathopod 1; (B) Right gnathopod 2; (C) Right pereopod 3; (D) Right pereopod 4. Scale bars:0.5 mm.

Figure 10. Metharpiniagrandirama Alonso de Pina,2003,female (UERJ 419):(A) Right pereopod 5; (B)Right pereopod 6; (C) Right pereopod 7. Scale bars:1.0 mm.

Figure 11. Metharpinia grandirama Alonso de Pina, 2003, female (UERJ 419): (A) Right epimeral plate 1; (B) Right epimeral plate 2; (C) Right epimeral plate 3; (D) Right uropod1; (E) Right uropod 2; (F) Right uropod 3;(G)Telson.Scale bars:0.5mm for A-C;0.2 mm for the remaining.