Microphoxus uroserratus Bustamante, 2002

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 : 29-35

Microphoxus uroserratus Bustamante, 2002 ( Figs. 23‑27 )

Microphoxus uroserratus Bustamante, 2002: 62 , 69, 76, 77, figs. 7‑12. Senna, 2010: 2077, 2116. Zalmon et al., 2013: 173, 176. Andrade et al., 2015: 33. Barros et al., 2017: 3. Negrello‑Filho et al., 2018: 259, 260, 262, 263. Serejo & Siqueira, 2018: 37.

Material examined: 1 ♀, dissected and drawn, MBT 163,

21°29′S, 40°56′W, 17 m depth, Rio de Janeiro state, 06

September 1970 ( UERJ 431 ) ; 1 ♀, dissected and drawn, MBT 157, 21°46′S, 40°58′W, 15 m depth, Rio de Janeiro state, 05 September 1970 ( UERJ 430 ) ; 1 ♀, in 70% ethanol, MBT 157, 21°46′S, 40°58′W, 15 m depth, Rio de Janeiro state, 05 September 1970 ( UERJ 432 ) ; 1 ♀, in 70% ethanol, MBT 157, 21°46′S, 40°58′W, 15 m depth, Rio de Janeiro state, 05 September 1970 ( MZUSP 41109 ) .

Diagnosis: Head, eyes rounded and medium‑sized; rostrum reaching half of article 2 of antenna 1. Antenna 2,article 4, ventral margin with 4 groups of setae. Mandibles, lacinia mobilis with 2 teeth. Gnathopod 1, coxa with setae posteroventrally. Epimeral plate 3, facial margin with a row of 7 simple setae. Urosomite 3, produced as a large acute hook dorsally. Uropod 1, peduncle without displaced stout seta; inner ramus with a row of stout setae dorsally. Uropod 2, peduncle with marginal stout setae; inner ramus without stout setae dorsally. Uropod 3, article 2 of outer ramus with 2 simple setae apically. Telson with 5 long setae dorsolaterally.

Description: Based on females (UERJ 430/UERJ 431). Habitus as in Fig. 23 . Head ( Fig. 24A, B ), eyes rounded and medium‑sized; rostrum constricted, narrow, elongate and spatulate, reaching half of article 2 of antenna 1. Antenna 1 ( Fig. 24C ), peduncle article 1 about 1.6× longer than wide, ventral margin with 3 brush setae, dorsal apex with 1 seta; article 2, ventral margin with 4 long setae, dorsal margin with 1 seta distally, facial margin with 1 brush and 1 long seta distally; article 3, short, ventral margin with 1 seta; primary flagellum 6‑articulate; accessory flagellum 4‑articulate. Antenna 2 ( Fig. 24D ), peduncle article 4, stout setae formula: 1‑3‑4‑4, ventral margin with 4 groups of medium to long setae and 1 stout seta ventrodistally, dorsal margin with 1 long and 2 stout setae; article 5, ventral margin with 1 brush seta and few long setae, facial margin with 3 stout setae medially; flagellum 7‑articulate. Left mandible ( Fig. 24E ), molar as a small hump with 6 stout setae, incisor with 3 teeth, lacinia mobilis with tiny cusps and 2 teeth, accessory setal row with 12 stout setae, palpar hump small; palp 3‑articulate, article 1 short, article 2 with 3 short and 2 long setae,article 3 about 1.3× longer than article 2, apex oblique, with 10 medium to long setae. Right mandible ( Fig. 24F ), molar as a small hump with 6 stout setae, incisor with 3 teeth, lacinia mobilis bifid, accessory setal row with 11 stout setae, palpar hump small; palp 3‑articulate, article 1 short, article 2 with 3 short and 2 long setae, article 3 about 1.4× longer than article 2, apex oblique, with 10 medium to long setae. Maxilla 1 ( Fig. 24H ), inner plate with 4 plumose setae apically; outer plate with 4 bifid stout setae and 6 multicuspidate stout setae apically; palp 2‑articulate, article 2 with 2 stout setae apically, medial margin with 4 setae, facial margin covered with setules. Maxilla 2 ( Fig. 24I ), inner plate, medial margin covered with long setules, apical and apicomedial margins with plumose setae; outer plate, slightly longer than inner, lateral margin with setules, apicolateral margin 4 short setae, apical and apicomedial margins with 8 long setae. Maxilliped ( Fig. 24G ), inner plate with 2 stout setae apically and plumose setae on medial and apical margins; outer plate with 7 bipectinate stout setae; palp, article 1 with 3 apicolateral setae; article 2, lateral margin with 7 setae, medial margin setose, article 3, moderately setose, article 4, narrow, with medium apical nail, partially embedded.

Gnathopod 1 ( Fig. 25A ), coxa subrectangular, ventral margin with 11 setae; basis, anterior margin with 1 short and 1 long seta distally; ischium, small and subrectangular, posterior margin with 1 long seta; merus, posterior margin with 5 long setae; carpus, anterior margin with 1 seta distally, posterior margin weakly setose; propodus, anterior margin with a tuft of setae distally, posterior margin weakly setose, with 1 stout seta defining palm; palm almost transverse, with setules, palmar hump small; dactylus slightly longer than palm. Gnathopod 2 ( Fig. 25B ), coxa subrectangular, weakly expanded distally, ventral margin with 7 setae; basis, anterior margin with 5 setae,posterior margin with 2 long setae medially, posterodistal corner with 1 long seta; ischium, small and subrectangular, posterior margin with 1 long seta; merus, posterior margin with 6 long setae; carpus, anterior margin with 1 long seta distally, posterior margin weakly setose, facial margin with 1 seta distally; propodus, anterior margin with a tuft of setae distally, posterior margin weakly setose, with 1 stout seta defining palm; palm almost transverse, with setules, palmar hump large; dactylus reaching the palmar corner. Pereopod 3 ( Fig. 25C ), coxa subrectangular, ventral margin with 5 setae; basis, about 3× longer than wide, posterior margin with 3 setae; ischium, small and subrectangular, posterodistal corner with 1 seta; merus, anterior margin with 1 seta distally, posterior margin moderately setose, facial margin with a distal row of 4 long setae; carpus, posterior margin with 6 long setae, with 1 subdistal thicker stout seta extending 85% of propodus, facial margin with a row of 4 setae; propodus, anterior margin with 1 short seta distally, posterior margin with 3 stout setae, facial margin with 4 stout setae; dactylus, about 50% the length of propodus. Pereopod 4 ( Fig. 25D ), coxa, subtriangular, posteroventral margin with 2 setae, posterodorsal margin weakly excavate; remaining articles are very similar to pereopod 3, differing only by some arrangements of setae. Pereopod 5 ( Fig. 26A ), coxa bilobate, posterior lobe with 5 setae ventrally; basis, anterior margin with 4 setae, anterodistal corner with a row of 4 setae extending to facial margin; ischium, small and subrectangular, anterodistal corner with a row of 4 setae extending to facial margin; merus more slender than in Mi cornutus , margins weakly setose, facial margin with 3 rows of stout setae: 5‑4‑6; carpus more slender than in Mi cornutus , margins weakly setose, facial margin with 4 rows of stout setae: 5‑3‑5‑6; propodus, anterior margin with 1 long and 3 stout setae medially, distally with 1 long and 2 stout setae, posterior margin with 1 long and 2 stout setae distally; dactylus, about 70% the length of propodus, with a short acute tooth distally. Pereopod 6 ( Fig. 26B ), coxa weakly produced posteroventrally, posterior lobe with 4 pappose setae; basis, anterior margin with 4 setae; ischium, small and subrectangular, anterodistal corner with 1 seta; merus more slender than in Mi cornutus , anterior margin with 1 long and 1 stout seta proximally, 3 stout setae medially and 4 stout setae distally, posterior margin with 1 pappose seta proximally, 3 long and 2 stout medially and a row of 5 stout setae distally; carpus more slender than in Mi cornutus , anteri‑ or margin with 4 stout setae medially and 5 distally, posterior margin with 2 stout setae medially and 3 distally; propodus, anterior margin with 4 stout setae medially and 3 distally, posterior margin with 2 stout setae medially and 3 distally; dactylus, about 50% the length of propodus. Pereopod 7 ( Fig. 26C ), coxa subtriangular, posteroventral margin with 1 short seta; basis, slightly longer than wide, expanded posteroventrally, almost reaching apex of merus, anterodistal corner with 1 seta, posterior margin serrate; ischium, small and subquad‑ rate, anterodistal corner with 1 seta; merus, anterior margin with 2 setae, posterior margin with 1 seta distally; carpus, anterior margin with 2 setae distally, posterior margin with 1 seta; propodus, anterior margin with 2 setae, posterior margin with 2 long setae distally; dactylus, about 75% the length of propodus.

Epimeral plate 1 ( Fig. 27A ),anteroventral margin round‑ ed, ventral margin covered with plumose setae, posterior margin weakly concave, with 4 setae. Epimeral plate 2 ( Fig. 27B ), anteroventral margin rounded, ventral margin with 9 long plumose setae, posterior margin weakly crenulate, with 6 setae. Epimeral plate 3 ( Fig. 27C ), anteroventral margin rounded, posteroventral corner with a row of 7 setae extending to facial margin, posterior margin weakly crenulate, with 12 setae. Urosomite 1, ventral margin with a tuft of setae. Urosomite 3, produced as a large acute hook dorsally. Uropod 1 ( Fig. 27D ), peduncle, about 2.4× longer than wide, dorsomedial margin with 1 long and 4 stout setae, apicolateral margin microscopically combed; outer ramus, slightly longer than inner, dorsal margin with 8 stout setae, bearing 2 subapical nails; inner ramus, dor‑ sal margin with 3 stout setae, bearing 1 subapical nail. Uropod 2 ( Fig. 27E ), peduncle, about 1.7× longer than wide, dorsomedialal margin with 6 stout setae, apicolateral margin microscopically combed, with 1 stout seta; outer ramus, slightly longer than inner, dorsal margin with 9 stout setae, bearing 1 subapical nail; inner ra‑ mus, dorsal margin bearing 1 subapical nail. Uropod 3 ( Fig. 27F ), peduncle, about 1.5× longer than wide, ventroapical margin with 4 stout setae, dorsoapical margin with 1 stout and 1 short seta, apicolateral margin with 1 long stout seta; outer ramus, 1.6× longer than inner, article 1, ventral margin with 2 acclivities bearing 3 and 2 stout setae respectively, distally with 2 stout setae, dorsal margin with 4 plumose setae, article 2, elongate, with 2 simple setae apically; inner ramus, dorsal margin with 5 long plumose setae. Telson ( Fig. 27G ), about 80% cleft, apical margin with 2 stout and 1 brush seta on each lobe,

lateral margins with 5 long setae, dorsolateral margin with 2 brush setae on each side.

Type locality: Sepetiba Bay, Rio de Janeiro state (22°58′S, 44°02′W).

Remarks: Since the material examined from station MBT 157 (UERJ 430) was partially damaged in the head and mouthparts, we selected a specimen from station MBT 163 (UERJ 431) to describe and draw mandibles, maxillae 1‑2 and maxilliped.

Microphoxus uroserratus was described by Bustamante (2002) with material from Sepetiba Bay, Rio de Janeiro. The species was previously recorded for the states of Ceará (Barros et al., 2017), Paraná (Negrello‑Filho et al., 2018) and Rio de Janeiro (Zalmon et al., 2013). As well as in Mi. cornutus , it is possible to notice morphological variations reflecting the maturation stages among the collected individuals of Mi. uroserratus in relation to the number of setae and armaments in antenna 2, pereopods, epimeral plates, uropods, and telson. On the original drawings by Bustamante (2002) it is possible to observe a lack of an acute lateral projection when analyzing the dorsal view of the head. However, it was possible to see this detail very clearly in our samples, leading us to suppose that this feature was overlooked during the description of the species.

Geographic distribution: Brazil: Sepetiba Bay and Campos Basin , Rio de Janeiro state ; Goiabeiras Beach, municipality of Fortaleza, Ceará state; Paranaguá Bay inlet, Paraná state .

Bathymetric range: Shallow waters to 97 m depth.

Figures

Figure 23. Microphoxus uroserratus Bustamante,2002,female (UERJ 430):(A) Habitus.Scale bar:1.0 mm.

Figure 24.Microphoxus uroserratusBustamante,2002:(A) Head inlateral view;(C) Right antenna1;(D) Right antenna2 (UERJ 430);(B) Head indorsalview;(E)Left mandible;(F) Right mandible;(G) Left maxilliped;(H) Left maxilla 1; (I) Left maxilla 2 (UERJ 431). Scale bars:0.5 mm for A-B;0.2 mm for the remaining.

Figure 25. Microphoxus uroserratus Bustamante,2002, female (UERJ 430): (A) Right gnathopod 1; (B) Right gnathopod 2; (C) Right pereopod 3; (D) Right pereopod 4. Scale bars:0.2 mm.

Figure 26. Microphoxusuroserratus Bustamante,2002,female (UERJ 430):(A) Right pereopod 5; (B) Right pereopod 6;(C) Right pereopod 7. Scale bars:0.2 mm.

Figure 27.Microphoxusuroserratus Bustamante,2002,female(UERJ430):(A) Right epimeralplate 1;(B)Right epimeralplate 2;(C)Right epimeralplate 3;(D)Right uropod1; (E) Right uropod2; (F) Right uropod 3;(G)Telson.Scale bars:0.3 mm for A;0.1 mm for G;0.2 mm for the remaining.