Pseudericthonius concavus, Souza-Filho & Serejo, 2014

Souza-Filho, Jesser F. & Serejo, Cristiana S., 2014, On the phylogeny of Ischyroceridae (Amphipoda, Senticaudata, Corophiida), with the description of a new genus and eight new species from deep-sea Brazilian waters, Zoological Journal of the Linnean Society 170 (1), pp. 34-85 : 79-82

PSEUDERICTHONIUS CONCAVUS SP. NOV.

( FIGS 31–33 )

Pseudericthonius sp. 1 Souza-Filho & Serejo, 2010d: 184.

Type material

Holotype: One female (2.7 mm) (dissected and drawn), OCEANPROF II, BC, #50, Campos Basin, Rio de Janeiro, Brazil, 22°04′33.9″S, 39°52′05.1W, 30 June 2003, 1050 m, MNRJ 21423 .

Paratypes: Two females, BARRACUDA-CARATINGA, #35, Campos Basin, Rio de Janeiro, Brazil, 22°35′10.8″S, 40°10′54.8″W, 19 May 2002, 1000 m, MNRJ 18142 . One female, BARRACUDA- CARATINGA, #38, Campos Basin, Rio de Janeiro, Brazil, 22°41′12.5″S, 40°14′10.7″W, 19 May 2002, 1100 m, MNRJ 19008 . Two females, BARRACUDA- CARATINGA, #32, Campos Basin, Rio de Janeiro, Brazil, 22°37′54.9″S, 40°17′31.34″W, 18 May 2002, 900 m, MNRJ 19199 . One female, BARRACUDA- CARATINGA, #33, Campos Basin, Rio de Janeiro, Brazil, 22°35′40.99″S, 40°15′5.12″W, 19 May 2002, 900 m, MNRJ 19202 . One female, OCEANPROF I, BC-SUL, # 67, Campos Basin , Rio de Janeiro, Brazil, 22°46′59.0″S, 40°7′49.44″W, 22 November 2002, 1650 m, MNRJ 21248 . One female, OCEANPROF II, BC-SUL , # 79, Campos Basin , Rio de Janeiro, Brazil, 22°20′22.7″S, 40°01′24.7″W, 21 June 2003, 750 m, MNRJ 21251 . Three females, OCEANPROF I, BC-SUL, # 79, Campos Basin , Rio de Janeiro, Brazil, 22°20′40.26″S, 40°00′35.1″W, 26 November 2002, 775 m, MNRJ 21253 . One female, OCEANPROF I, BC-SUL, # 64, Campos Basin , Rio de Janeiro, Brazil, 22°36′30″S, 40°21′45.36″W, 22 November 2002, 750 m, MNRJ 21254 . One female, OCEANPROF II, BC-NORTE , # 44, Campos Basin , Rio de Janeiro, Brazil, 22°11′43.5″S, 39°54′45″W, 1 July 2003, 749 m, MNRJ 21255 . Two females, OCEANPROF I, BC- SUL, #69, Campos Basin , Rio de Janeiro, Brazil, 22°31′12.47″S, 40°1511.08″W, 22 November 2002, 750 m, MNRJ 21256 . One female, OCEANPROF II, BC-SUL , # 74, Campos Basin , Rio de Janeiro, Brazil, 22°28′31.1″S, 40°09′23.5″W, 18 June 2003, 750 m, MNRJ 21258 . One female, OCEANPROF I, #50, Campos Basin , Rio de Janeiro, Brazil, 22°04′33.99″S, 39°52′04.97″W, 24 November 2002, 1050 m, MNRJ 21259 . One female, OCEANPROF I, BC-SUL, # 74, Campos Basin , Rio de Janeiro, Brazil, 22°27′31.62″S, 40°09′23.19″W, 21 November 2002, 750 m, MNRJ 21260 . One female, OCEANPROF II, BC-SUL , # 59, Campos Basin , Rio de Janeiro, Brazil, 21°53′59.2″S, 39°55′32.2″W, 29 June 2003, 750 m, MNRJ 21261 . Two females, OCEANPROF II, BC-SUL , # 70, Campos Basin , Rio de Janeiro, Brazil, 22°35′03.7″S, 40°08′52.5″W, 15 June 2003, 1050 m, MNRJ 21262 . One female, OCEANPROF II , BC, #50, Campos Basin , Rio de Janeiro, Brazil, 22°04′33.9″S, 39°52′05.1″W, 30 June 2003, 1050 m, MNRJ 21263 . Two females, OCEANPROF I, BC-SUL, # 84, Campos Basin , Rio de Janeiro, Brazil, 22°26′27.7″S, 39°58′51.65″W, 20 November 2002, 1050 m, MNRJ 21265 . One female, OCEANPROF I, BC-SUL, # 65, Campos Basin , Rio de Janeiro, Brazil, 22°41′55.68″S, 40°16′30.36″W, 22 November 2002, 1050 m, MNRJ 21266 .

Type locality

Campos Basin, Rio de Janeiro, Brazil.

Diagnosis

Antenna 1 accessory flagellum present, rudimentary, 1-articulate. Eyes absent. Mandibular palp very long, 3.4 times length of mandibular body, article 2 longer than article 3. Gnathopod 1 carpus longer than propodus (1.4×), posterior margin densely setose, posterodistal angle oblique. Gnathopod 2 weakly carporchelate; basis moderately stout, enlarged distally; carpus triangular and massive, posterior margin with long setae, posterodistal angle produced into a subacute process; propodus subequal to carpus, anterior margin with long setae; palm rounded and minutely serrate, with long facial setae. Pereopod 5 basis subrectangular, three times longer than wide; dactylus with one accessory spine. Pereopods 6 and 7 dactylus with one accessory spine. Uropod 1 outer ramus with one long and robust apical seta, about 0.8 × ramus length, and one short apical robust seta; inner ramus half as long as outer ramus, with a short apical seta. Uropod 2 inner ramus half as long as outer ramus; inner ramus naked. Uropod 3 ramus without marginal robust setae, tip recurved with two spines and two setae. Telson subrectangular; wider than long, with shallow excavation distally and two patches of spines on both sides of telson.

Description

Based on holotype female (2.7 mm), MNRJ 21423. Antenna 1 article 3 longer than article 1; flagellum with five articles, accessory flagellum present, rudimentary, 1-articulate. Head longer than pereonites 1 and 2 together; anteroventral margin strongly recessed; eyes absent; lateral cephalic lobe acute. Epistome acute and curved upwards. Upper lip with distal notch. Mandibular palp very long, 3.4 times length of mandibular body, article 2 longer than article 3, with facial and marginal setae, article 3 marginal and distal long setae. Lower lip, mandibular process acute. Maxilla 1 inner plate with a row of marginal setae; outer plate with seven robust setae; palp with four apical robust setae and two facial setae. Maxilla 2 outer plate broader than inner plate; inner plate with a row of facial setae. Maxilliped inner plate extending beyond end of palp article 1; outer plate reaching about two-thirds along palp article 2; article 4 with a long apical robust setae.

Coxae 1–7 wider than long, mostly discontinuous. Coxae 1 and 2 anteroventral angle rounded and not produced. Coxae 3 and 4 similar in shape, and as deep as coxae 1 and 2. Coxa 5 as long as coxae 1–4, with a few long setae on distal margin. Coxae 6 and 7 short, similar in shape, shorter than others. Gnathopod 1 basis slender, posterior margin convex; carpus longer than propodus (1.4×), posterior margin densely setose, posterodistal angle oblique; propodus suboval, with long setae on antero, postero, and facial margin; palm evenly rounded and minutely serrate, without palmar corner; dactylus moderately stout, reaching end of palm. Gnathopod 2 weakly carporchelate; basis moderately stout, enlarged distally; carpus triangular and massive, posterior margin with long setae, posterodistal angle produced into a subacute process; propodus subequal to carpus, anterior margin with long setae; palm rounded and minutely serrate, with long facial setae. Pereopods 3 and 4 similar in shape and length, basis suboval, moderately inflated; merus, anterior margin well produced; dactylus longer than propodus. Pereopod 5 basis subrectangular, three times longer than wide; merus three times longer than wide; propodus long, 5 × carpus length; dactylus with one accessory spine. Pereopods 6 and 7 similar in shape, basis subrectangular, 2.1 times longer than wide; merus long, about 1.25 × propodus length; propodus a tuft of setae on posterodistal angle; dactylus with one accessory spine.

Epimera 1–3 distoventral margin rounded. Epimeron 3 posterior margin smooth. Uropod 1 long, peduncle with distoventral corona of spines, without robust setae on outer margin; outer ramus with outer and inner margins naked, with one long and robust apical seta about 0.8 × ramus length and one short apical robust seta; inner ramus half as long as outer ramus, with a short apical seta. Uropod 2 peduncle with distoventral corona of spines, without robust setae along outer margin; outer ramus without setae;

82 J. F. SOUZA-FILHO AND C. S. SEREJO

inner ramus half as long as outer ramus; inner ramus naked. Uropod 3 peduncle without subapical setae; ramus without marginal robust setae, tip recurved, with two spines and two setae. Telson subrectangular; wider than long, with shallow excavation distally and two patches of spines on both sides of telson.

Tube

Composed of fine detritus and short sand grains.

Etymology

The specific name is derived from the Latin concavus , meaning concave. It refers to the excavation on the telson tip, which is unique within the genus.

Remarks

Pseudericthonius concavus sp. nov. is distinguished from all its congeners in having a sparsely setose coxa 5, the basis of pereopod 5 subrectangular, uropods 1 and 2 with the inner ramus reaching about midlength of the outer ramus, and lacking robust marginal setae. Also, both rami of uropod 2 lack distal setae, and the distal margin of the telson is concave, without an acute middle process.

Geographic distribution

South-western Atlantic: Campos Basin, Rio de Janeiro, Brazil.

Figures

Figure 31. Pseudericthonius concavus sp. nov. Holotype, female (2.7 mm), OCEANPROF II BC, #50, 30 June 2003, 1050 m, MNRJ 21423.

Figure 32. Pseudericthonius concavus sp. nov. Holotype, female (2.7 mm), OCEANPROF II BC, #50, 30 June 2003, 1050 m, MNRJ 21423.

Figure 33. Pseudericthonius concavus sp. nov. Holotype, female (2.7 mm), OCEANPROF II BC, #50, 30 June 2003, 1050 m, MNRJ 21423.