Heterophoxus shoemakeri, Andrade & Senna, 2020

Andrade, Luiz F. & Senna, André R., 2020, A novel species of Heterophoxus Shoemaker, 1925 (Crustacea, Amphipoda, Phoxocephalidae) from southeast and southern Brazil, with an identification key to world species of the genus, European Journal of Taxonomy 592, pp. 1-16 : 3-11

Heterophoxus shoemakeri sp. nov.

urn:lsid:zoobank.org:act:B3D28885-EAEE-49E9-974C-528AB9B28BE7

Figs 1–6

Diagnosis

Head, eyes present, rostrum unconstricted. Antenna 2, peduncle article 1 ensiform; article 4 without posteroproximal lobe, with one brush seta facially. Mandible, molar as a small hump with three stout setae, right lacinia mobilis bifid, left lacinia mobilis flabellate. Maxilla 1, inner plate with two plumose setae; palp 2-articulate. Maxilliped, inner plate with one stout seta apically; palp, article 4 with long apical nail. Gnathopods 1–2, carpus subtriangular; propodus, palm acute and subchelate. Pereopod 5, coxa strongly expanded posteroventrally; basis narrow and slender. Pereopod 6 as long as than the other pereopods. Pereopod 7, basis expanded posteroventrally, exceeding half of merus. Epimeral plate 3, posteroventral corner with an acute projection, posterior margin covered with setules. Uropods 1–2, rami with stout setae, but not distributed continuously to apex. Uropod 3, outer ramus about twice as long as inner ramus, article 2 short, with two long setae apically; inner ramus with one long seta apically. Telson short, about 65% cleft, each lobe with 1 stout seta apically.

Etymology

The species name is a tribute to Dr Clarence Raymond Shoemaker, for his worldwide contributions to the knowledge of the amphipods.

Material examined

Holotype

BRAZIL • ♀; coast of Rio de Janeiro State, MBT station 141; 23°25′ S, 43°00′ W; depth 113 m; 2 Sep. 1970; dredged; UERJ 433 .

Paratypes

BRAZIL • 1 ♂; coast of Rio de Janeiro State, MBT station 206; 23°14′ S, 44°03′ W; depth 52 m; 3 Jun. 1971; dredged; UERJ 434 • 1 subadult ♂; same collection data as for holotype; UERJ 435 • 14 ♀♀; coast of Rio de Janeiro State, MBT station 155; 22°22′ S, 41°32′ W; depth 34 m; 5 Sep. 1970; dredged; UERJ 436 • 1 ♀; coast of Rio de Janeiro State, MBT station 210; 23°46′ S, 43°10′ W; depth 128 m; 4 Jun. 1971; dredged; UERJ 437 • 2 ♀♀; coast of Santa Catarina State, MBT station 129; 29°13′ S, 49°25′ W; depth 27 m; 25 Jun. 1970; dredged; UERJ 438 • 5 ♂♂, 11 ♀♀; coast of Rio Grande do Sul State, MBT station 137; 30°03′ S, 50°04′ W; depth 25 m; 26 Jun. 1970; dredged; UERJ 439 • 9 ♀♀; coast of Rio Grande do Sul State, MBT station 127; 29°33′ S, 48°46′ W; depth 118 m; 25 Jun. 1970; dredged; UERJ 440 .

Description

Holotype

HABITUS. As in Fig. 1A.

HEAD ( Fig. 2A ). Eyes present, rounded, dark in alcohol; rostrum entire, unconstricted. Antenna 1 ( Fig. 2B ), peduncle article 1 stout, about 1.4× as long as wide, ventral margin with four brush setae, dorsal margin with setules and one pappose seta distally; article 2, short, ventral margin with seven long pappose setae, facial margin with one brush seta; article 3, short, ventral margin with two setae, facial margin with two brush setae and three simple setae distally; primary flagellum 7-articulate; accessory flagellum 5-articulate. Antenna 2 ( Fig. 2C ), peduncle article 1 ensiform; article 3, ventral margin with three pappose setae, dorsal margin with one long seta distally; article 4, ventral margin with long pappose setae, facial margin with two brush setae and a row of long setae extending to dorsal apex; article 5, about 0.7× the length of article 4, ventral margin with five pappose, one brush seta and two distal setae; flagellum 7-articulate. Left mandible ( Fig. 2D ), molar as a small hump with three bipectinate stout setae, incisor with five teeth, lacinia mobilis flabellate, accessory setal row with 10 multicuspidate stout setae, palpar hump medium; palp 3-articulate, article 1 short, article 2, curved, about 4.6× as long as wide, with one medial and two distal setae, article 3, about 1.2× as long as article 2, with two long setae medially, apex oblique, with six medium to long setae. Right mandible ( Fig. 2E ), molar as a small hump with three bipectinate stout setae, incisor with seven teeth, lacinia mobilis bifid, with small cusps, accessory setal row with eight multicuspidate stout setae, palpar hump medium; palp 3-articulate, article 1 short, article 2, curved, about 4.7× as long as wide, with one proximal and three distal setae, article 3, about 1.4× as long as article 2, with two long setae medially, apex oblique, with seven medium to long setae. Maxilla 1 ( Fig. 2G ), inner plate with two plumose setae; outer plate, with nine stout multicuspidate setae; palp 2-articulate, article 2 with six setae forming a row medially and two stout plus two long setae apically. Maxilla 2 ( Fig. 2H ), inner plate subequal to outer plate, with nine plumose setae, medial margin with row of setules; outer plate, with eight long pectinate setae apically and two mid-lateral setae, lateral margin with row of setules. Maxilliped ( Fig. 2F ), inner plate with one short stout seta apically and six long plumose setae; outer plate with seven stout setae medially, two stout paposerrate setae apically and two long pappose setae laterally, with the exception of the proximalmost ones, these setae are strongly curved; palp, article 2, medial margin weakly setose, article 3 subrounded, weakly setose, article 4 subtriangular, with two setae on the sides, two apical setae and one long apical nail.

PEREON. Gnathopod 1 ( Fig. 3A ), coxa, ventral margin expanded, convex, with 15 pappose setae; basis, about 2.4× as long as wide, posterior margin with four long plumose setae medially and three long setae distally; ischium small and subrectangular, posterior margin with one pappose and two simple setae; merus, posterior margin with five pappose setae, facial margin with one long seta; carpus short, 1.2× as long as wide, anterior margin with one seta distally, posterior margin with seven long setae; propodus, 2.2× as long as wide, anterior margin with a tuft of setae distally, posterior margin weakly setose, with one stout seta defining palm, palmar hump large; palm acute; dactylus reaching palmar corner, outer margin with one short seta distally. Gnathopod 2 ( Fig. 3B ) slightly larger than gnathopod 1; coxa subrectangular, ventral margin with nine pappose setae, anterior margin very weakly concave; basis about 2.9× as long as wide, posterior margin with two long setae medially and three long pappose setae distally; ischium small and subrectangular, posterior margin with two long pappose setae and row of four pappose setae extending to facial margin; merus, posterior margin with six pappose setae, facial margin with one pappose seta; carpus short, subtriangular, slightly wider than long, anterior margin with one long seta distally, posterior margin with two pappose and two simple setae; propodus, 2× as long as wide, anterior margin with tuft of setae distally, posterior margin weakly setose, with one stout seta defining palm, palmar hump large; palm acute; dactylus reaching palmar corner, outer margin with one short seta distally. Pereopod 3 ( Fig. 3C ), coxa subrectangular, ventral margin with eight plumose setae; basis about 2.6× as long as wide, posterior margin with four long setae medially and four long pappose setae distally; ischium small and subrectangular, posterior margin with row of six pappose setae extending to facial margin; merus expanded anteriorly, anterior margin with five pappose setae distally, posterior margin moderately setose with medium to long pappose setae; carpus, posterior margin moderately setose, with two stout setae, being the distalmost almost reaching apex of dactylus; propodus, posterior margin with six long setae; dactylus, about 50% the length of propodus. Pereopod 4 ( Fig. 3D ), coxa strongly expanded posteriorly, posterodorsal margin excavate, ventral margin with 12 plumose setae; basis, about 2.7× as long as wide, posterior margin with three long setae medially, posterodistal corner with one long pappose seta; ischium, small and subrectangular, posterodistal corner with two long pappose setae; merus, anteriorly expanded, posterior margin moderately setose with long pappose setae; carpus, anterior margin with one short seta distally, posterior margin moderately setose, facial margin with four setae, with two stout setae, being the distalmost almost reaching the apex of dactylus; propodus, anterior margin with two short setae distally, posterior margin with five long setae; dactylus, about 55% as long as propodus. Pereopod 5 ( Fig. 4A ), coxa bilobate, expanded posteroventrally, posteroventral lobe with six pappose setae; basis, about 2.9× as long as wide, anterior margin with two long setae medially and three pappose and one simple seta distally, posterior margin with one long pappose seta medially; ischium small and subrectangular, anterior margin with three pappose setae distally; merus, anterior margin moderately setose, with three stout setae medially and a row of four stout setae extending to facial margin, posterior margin with four long pappose setae medially and one plumose and one stout seta distally; carpus, anterior margin moderately setose, with long pappose and stout setae, posterior margin with five plumose and two stout setae medially, distally with three plumose and three stout setae; propodus, anterior margin with one stout and three pappose setae, posterior margin with one stout and four plumose setae medially, facial margin five long and two stout setae distally; dactylus, about 70% as long as propodus. Pereopod 6 ( Fig. 4B ), much longer than the remaining pereopods; coxa, weakly expanded posteroventrally, posterior margin with one short seta and covered with setules; basis, about 1.3× as long as wide, anterior margin convex, posterior margin concave, margins covered with plumose setae; ischium, small and subrectangular, anterior margin with two plumose setae; merus, 2.7× as long as wide, anterior margin with two stout setae, posterior margin with two plumose setae proximally, one stout and one long seta medially, and three stout setae distally; carpus, anterior margin with four sets of stout setae (2-2-2-3), posterior margin with three long and four stout setae; propodus, 8.6× as long as wide, anterior and posterior margins with long and stout setae; dactylus elongate, about 60% the length of propodus. Pereopod 7 ( Fig. 4C ), coxa, small and subrounded, posteroventral margin with one short seta and row of setules; basis, about 1.3× as long as wide, strongly expanded posteroventrally, exceeding half of merus, posterior margin serrate, with plumose setae in inter-dental notches; ischium, 1.5× as long as wide, distal lobe produced, anterior margin with two stout setae medially, anterodistal corner with three pappose setae; merus, anterior margin with four stout and three pappose setae, posterior margin with two stout setae distally; carpus, anterior margin with three setae, posterior margin with two plumose setae distally; propodus, anterior and posterior margins with two setae each; dactylus, elongate, slightly longer than propodus.

PLEON. Epimeral plate 1 ( Fig. 5A ), anteroventral corner with two plumose setae, posterior margin convex, anteromedial to posterior margins covered with setules. Epimeral plate 2 ( Fig. 5B ), anteroventral corner rounded, ventral margin with six plumose setae, posteroventral corner with a small subrounded projection, posterior margin convex, covered with setules. Epimeral plate 3 ( Fig. 5C ), anteroventral corner rounded, ventral margin weakly concave, with four plumose and four pappose setae, posteroventral corner with a long acute projection, posterior margin covered with setules. Uropod 1 ( Fig. 5D ), peduncle 4.8× as long as wide, dorsomedial margin with five stout setae, dorsolateral margin with two stout setae; outer ramus, dorsal margin with two stout setae and one apical nail; inner ramus subequal to outer, dorsal margin with two stout setae. Uropod 2 ( Fig. 5E ), peduncle 2.8× as long as wide, dorsomedial margin with six stout setae, ventrolateral margin with two stout setae; outer ramus, dorsal margin with two stout setae and one subapical seta; inner ramus subequal to outer, dorsolateral margin with one stout seta. Uropod 3 ( Fig. 5F ), peduncle 1.8× as long as wide, with five stout setae distally; outer ramus, article 1, lateral margin with two long setae, apical margin with one short and two long setae, article 2, short, about 1.7× as long as wide, with two long setae apically; inner ramus, about 50% the length of outer, with one long seta apically. Telson ( Fig. 5G ), short, about 65% cleft, with one stout seta on each lobe.

Paratypes and sexual dimorphism variations

Paratype (♂, UERJ 434)

HABITUS ( Fig. 1B ). Smaller in size.

HEAD ( Fig. 6A ). Eyes larger and more pigmented, kidney-shaped, rostrum unconstricted. Antenna 1 ( Fig. 6B ), peduncle article 1, stout, about 1.5× as long as wide, ventral margin with seven brush setae, facial margin with a dense tuft of long setules, dorsal margin with setules medially and one long seta distally; article 2, short, ventral margin with seven long setae; article 3, about 50% the length of article 2, ventral margin with two setae, facial margin with two brush setae; primary flagellum 5-articulate; accessory flagellum 7-articulate, with calceoli present on articles 1–3. Antenna 2 ( Fig. 6C ), peduncle article 1 ensiform; article 3, ventral margin with three setae, dorsal margin covered with long setules; article 4, ventral margin with short to long setae, facial margin with two brush setae and a row of long setae extending to dorsal apex, dorsal margin with long setules; article 5, dorsal margin with four calceoli; flagellum 19-articulate, with setules and 10 calceoli.

PEREON. Gnathopods 1–2 ( Fig. 6 D–E), similar in size, but more robust and with a longer propodus than in female.

PLEON. Uropod 3 ( Fig. 6F ), peduncle 1.3× as long as wide, with seven stout setae distally; outer ramus, article 1, margins covered with long plumose setae, article 2, with two long plumose setae apically; inner ramus, equals outer ramus in length, margins covered with long plumose setae.

Paratype (♂ subadult, UERJ 435)

Antenna 2 ( Fig. 6G ), without calceoli; flagellum stouter and shorter than in adult males, with 12 articles.

Remarks

The only species of the genus doubtfully cataloged for Brazilian waters is H. videns , recorded from São Paulo State. The original description of the species by K.H. Barnard (1930) and subsequent works with diagnoses and illustrations ( Schellenberg 1931; Nicholls 1938; J.L. Barnard 1960) are not enough to make a complete comparison between H. shoemakeri sp. nov. and H. videns . The best-represented scheme of this species in which is possible to check important diagnostic characters was provided by Bellan-Santini (1972). Heterophoxus shoemakeri sp. nov. can be distinguished from H. videns by the following states of characters ( H. videns characters in parentheses): mandible palp, article 2 curved (straight); maxilliped, outer plate with strongly curved stout setae (not curved); pereopod 6, basis, posterior margin concave (very weakly concave); pereopod 7, basis, posterior margin serrate with acute teeth (large rounded teeth), merus, posterior margin not produced distally (produced into a rounded lobe); epimeral plate 3, posteroventral corner with a long acute projection (short), posterior margin almost straight (sinuous); uropod 3, outer ramus, article 2 clearly present in both sexes (doubtful/absent in males).

Type locality Rio de Janeiro State coast (23°25′ S, 43°00′ W).

Distribution

The species is known from the coasts of the states of Rio de Janeiro, Santa Catarina and Rio Grande do Sul ( Fig. 7 ), between 25 and 128 meters depth.

Figures

Fig. 1. Heterophoxus shoemakeri sp. nov., habitus. A. Holotype, ♀ (UERJ 433). B. Paratype, ♂ (UERJ 434). Scale bars = 1.0 mm.

Fig. 2. Heterophoxus shoemakeri sp. nov., holotype, ♀ (UERJ 433). A. Head. B. Antenna 1. C.Antenna 2. D. Left mandible. E. Right mandible. F. Maxilliped. G. Maxilla 1. H. Maxilla 2. Scale bars: A = 0.5 mm; B–F = 0.2 mm; G–H = 0.1 mm.

Fig. 3. Heterophoxus shoemakeri sp. nov., holotype, ♀ (UERJ 433). A. Gnathopod 1. B. Gnathopod 2. C. Pereopod 3. D. Pereopod 4. Scale bars = 0.2 mm.

Fig. 4. Heterophoxus shoemakeri sp. nov., holotype, ♀ (UERJ 433). A. Pereopod 5. B. Pereopod 6. C. Pereopod 7. Scale bars = 0.2 mm.

Fig. 5. Heterophoxus shoemakeri sp. nov., holotype, ♀ (UERJ 433). A. Epimeral plate 1. B. Epimeral plate 2. C. Epimeral plate 3. D. Uropod 1 E. Uropod 2. F. Uropod 3. G. Telson. Scale bars: A–E, G = 0.2 mm; F = 0.1 mm.

Fig. 6. Heterophoxus shoemakeri sp. nov. A–F. Paratype, ♂ (UERJ 434). A. Head. B. Antenna 1. C. Antenna 2. D. Gnathopod 1. E. Gnathopod 2. F. Uropod 3. G. Paratype, subadult ♂ (UERJ 435). Antenna 2. Scale bars: A = 0.5 mm; B–F = 0.2 mm; G = 0.1 mm.

Fig. 7. Distribution of Heterophoxus shoemakeri sp. nov.