Metharpinia protuberantis Alonso de Pina, 2001

Metharpinia protuberantis Alonso de Pina, 2001 View in CoL

( Figs. 15–19 View Figure 15 View Figure 16 View Figure 17 View Figure 18 View Figure 19 )

Metharpinia protuberantis Alonso de Pina, 2001: 527 View in CoL , figs. 7–11. — Alonso de Pina, 2003a: 1044. — Alonso de Pina, 2003b: 2521. — De Broyer et al., 2007: 190. — Alonso de Pina et al., 2008: 17–19, 33, 34. — Storero and González, 2008: 1056. — Alonso and Chiesa, 2014: 206,207, 209, fig.3D. — Andrade et al., 2015: 34, 39. — Andrade and Senna, 2020c: 2, 22.

Material examined. 1 female, dissected and illustrated, st. 2886, 38°06’S 55°13’W, Argentina, 440–480 m depth, February 1972 ( UERJ 460 ) GoogleMaps .

Diagnosis. Head with medium-sized and rounded eyes, rostrum constricted, narrow, elongate and spatulate, reaching half of article 2 of antenna 1. Antenna 2 article 4 with 4 rows of facial stout setae. Mandible molar as hump with 5 stout setae plus 1 displaced, incisor with 3 teeth, left lacinia mobilis with 5 teeth, right lacinia mobilis bifid. Maxilliped inner plate with 2 stout setae apically. Gnathopods 1–2 propodus elongate, palm acute and almost transverse. Epimeral plate 3 posteroventral corner strongly produced as acute spine, with oblique facial row of stout setae. Urosomite 3 produced dorsally into acute, triangular process.

Redescription (based on female, UERJ 460).Habitus as in Fig.15 View Figure 15 . Antenna 1 peduncle article 1 with 5 brush setae, dorsal apex with 1 seta; article 2 ventral margin with 5 setae; article 3 ventral margin with 2 setae, with 2 facial brush setae; primary flagellum 10-articulate; accessory flagellum 7-articulate. Antenna 2 article 3 dorsally and facially with 1 short and 1 long seta respectively; article 4 facial stout setae formula: 1-3- 4-3, ventral margin with medium to long setae, dorsal margin with 1 stout and 1 long seta medially; article 5 facially with 1 plumose and 3 stout setae, plus 1 stout seta distally, ventral margin with short to long setae and 2 stout setae distally; flagellum 12-articulate. Mandible incisor with 3 teeth (left and right); lacinia mobilis with 5 teeth (left) and bifid (right); molar as hump with 6 slender setae (left and right); accessory setal row with 12 multicuspidate stout setae (left and right); palp 3-articulate, article 2 medial margin with 4 setae (left and right), article 3 about 1.3 × longer than article 2, medial margin with 3 setae proximally, apex oblique, with 11 medium to long setae (left and right). Maxilla 1 inner plate with 4 plumose setae apically, medial margin with row of setules; outer plate with 10 stout setae, 4 bifid; palp 2-articulate, article 2 facial and medial margins setulose, apical and subapical margins with row of 3 stout and 5 slender setae.Maxilla 2, inner plate about 0.8 × length of outer, medial margin setulose, with row of 10 plumose setae extending to apex; outer plate lateral margin setulose, apical margin with 12 short to long setae. Maxilliped inner plate medial margin with row of setules, medial margin with 5 plumose setae, apical margin with 2 stout and 3 plumose setae, lateral margin with 2 short plumose setae; outer plate medial margin with 1 long and 5 bipectinate stout setae, apical margin with 2 bipectinate stout setae, lateral margin with row of setules distally; palp article 1 lateral margin with 2 long setae, article 2 medial margin moderately setose, lateral margin with 4 setae, article 3 medial margin with 6 setae, with 5 facial setae, lateral margin with 1 seta medially and 4 distally, article 4 elongate, bearing 1 medium apical nail, partially immersed.

Gnathopod 1 weakly setose; coxa subrectangular, ventral margin with 16 setae; carpus about 1.2 × longer than propodus; propodus anterior margin with 6 setae distally, posterior margin weakly setose, with 1 stout seta defining palm; palm acute, with setules, palmar hump small; dactylus reaching palmar corner. Gnathopod 2 weakly setose, coxa subrectangular, ventral margin with 10 setae; carpus slightly longer than propodus; propodus posterior margin weakly setose, with 1 stout seta defining palm; palm acute with setules, palmar hump medium; dactylus reaching palmar corner. Pereopod 3 weakly setose; coxa subrectangular, ventral margin with 7 setae; carpus posterior margin weakly setose, distally with 1 long stout seta extending about 85 % length of propodus, with facial row of 5 setae; propodus with 6 posterior and facial stout setae; dactylus about 40 % length of propodus, with acute spine distally. Pereopod 4 similar to pereopod 3, weakly setose; coxa produced posteriorly, weakly excavate posterodorsally, posteroventral margin with 8 setae; merus less stout than in pereopod 3; carpus posterior margin weakly setose, distally with 1 long stout seta extending to 75 % length of propodus. Pereopod 5 coxa bilobate, posteroventral margin with 6 setae; basis about 1.7 × longer than wide, anterior margin with 13 setae; merus anterior margin moderately setose, posterior margin with 3 pappose setae, with 5 facial rows of stout setae: 5-2-5-6-8; carpus anterior margin setose, with 2 stout setae proximally and 3 medially, posterior margin with 5 pappose setae, with 3 facial rows of stout setae: 4-5-6; propodus anterior margin with 5 pappose and 7 stout setae, posterior margin with 6 pappose setae; dactylus about 50 % length of propodus. Pereopod 6 coxa posteroventral margin with 10 setae; basis about 1.2 × longer than wide, anterior margin with medium to long setae; merus anterior and posterior margins with medium to long slender and stout setae, with 4 facial rows of stout setae: 2-2-5-7; carpus anterior margin with 3 sets of 3 stout setae, posterior margin with 3 sets of stout setae: 3-5-4; propodus anterior and posterior margins with distal 2 stout setae each, with 5 facial sets of stout setae: 3-1-3-3-3; dactylus about 35 % length of propodus. Pereopod 7 weakly setose; coxa subtriangular, posteroventral margin with 2 setae; basis about 1.4 × longer than wide, expanded posteroventrally, reaching the apex of carpus, posterior margin weakly crenulate; ischium, merus, carpus and propodus with sparse setae on margins; dactylus about 80 % length of propodus, with 1 plumose seta.

Epimeral plate 1 anterior margin with 4 plumose setae, ventral margin convex, with 10 plumose setae, posteroventral corner produced into short subacute spine, posterior margin convex, with 2 setae. Epimeral plate 2anterior margin concave, ventral margin convex, with 9 plumose setae, posteroventral corner produced into short subacute spine, posterior margin weakly crenulate, with 3 setae. Epimeral plate 3 anterior margin concave, anteroventral corner produced, with 3 setae, ventral margin with concavity, posteroventral corner strongly produced as acute spine, posterior margin with 4 setae, with oblique facial row of 8 stout setae. Urosomite 1 with ventral tuft of setae. Uropod 1 peduncle dorsomedial margin with 1 slender and 2 stout setae, dorsolateral margin with 1 seta distally; outer ramus slightly longer than inner, dorsal margin with 5 stout setae, bearing 2 subapical nails; inner ramus dorsal margin with 3 stout setae, bearing 1 subapical nail. Uropod 2 peduncle dorsomedial margin with 5 stout setae, dorsodistal corner combed, dorsolateral margin with 1 stout seta; outer ramus 1.2 × longer than inner, dorsal margin with 4 stout setae, bearing 1 subapical nail; inner ramus dorsal margin with 2 stout setae, bearing 1 subapical nail. Uropod 3 peduncle 1 dorsomedial and dorsolateral margins with 1 stout seta each, ventrodistal corner with 4 stout setae; outer ramus 1.5 × longer than inner, article 1 ventrolateral margin with 3 sets of 2 stout setae, article 2 elongate, with 2 plumose setae apically; inner ramus dorsal margin with 1 plumose seta medially and subapically.

Type locality. Argentina, Península Valdés , Punta

Pardelas (42°37’S 64°16’W).

Remarks. Metharpinia protuberantis was described with material from Chubut, Argentinean Patagonia ( Alonso de Pina, 2001). The species is considered intermediate between Metharpinia Schellenberg, 1931 and Microphoxus Barnard, 1960 , being easily distinguished by presenting epimeral plate 3 posteroventral corner with a strong spine pointing upwards. It is relevant to highlight that a very variable character such as the facial stout setae formula (1-3- 4-3) present on the fourth article of antenna 2 is the same for both the type material and the one examined here. Besides some subtle differences, such as the setation on mouthparts and appendages, there are some distinctions when compared to the type material (characters of type material in parentheses): pereopod 7 propodus distally smooth, without processes (vs combed, with five digital processes); epimeral plate 3 posterior margin smooth (vs weakly crenulate); uropod 1 dorsodistal corner not combed (vs coarsely combed).

In this study, we propose a diagnosis of the species for the first time. This new record represents the northernmost for the species ( Fig. 25 View Figure 25 ), previously known from the northern Magellanic region, on the Atlantic coast of Patagonia.

Geographic distribution. Argentina: Punta Pardelas, Peninsula Valdés (42°31’S 64°16’W) GoogleMaps , Punta Verde and Banco Reparo, Patagonia (40°42’S – 40°50’S / 64°43’W – 65°07’W) GoogleMaps , and off Buenos Aires Province (38°06’S 55°13’W) GoogleMaps .

Bathymetric range. The species was previously reported from 2–10 meters depth. In this study, M. protuberantis was collected at 440–480 meters depth, demonstrating that this species is not restricted to shallow waters and presents a wide bathymetric range.