Pseudericthonius bousfieldi, 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 : 76-79

PSEUDERICTHONIUS BOUSFIELDI SP. NOV.

( FIGS 28–30 )

Pseudericthonius sp. 2 Souza-Filho & Serejo, 2010c: 186.

Type material

Holotype: Male (3.8 mm) (dissected and drawn), OCEANPROF II, BC– NORTE, #44, Campos Basin ,

Rio de Janeiro, Brazil, 22°10′43.5″S, 39°54′45″W, 1 July 2003, 749 m, MNRJ 21257 .

Paratypes: One male and two females (one dissected and drawn), OCEANPROF II, BC-SUL , # 75, Campos Basin , Rio de Janeiro, Brazil, 22°31′28.3″S, 40°03′49.3″W, 18 June 2003, 1050 m, MNRJ 21250 . One female, OCEANPROF II, BC-SUL , # 84, Campos Basin , Rio de Janeiro, Brazil, 22°26′28.8″S, 39°58′53.3″W, 20 June 2003, 1050 m, MNRJ 21246 . One male and one female, OCEANPROF II, BC- SUL, #79, Campos Basin , Rio de Janeiro, Brazil, 22°20′22.4″S, 40°01′24.7″W, 21 June 2003, 750 m, MNRJ 21247 . Two females, #RONCADOR, Campos Basin, Rio de Janeiro, Brazil, 21°58′32.2″S, 39°51′52.66″W, 24 September 2001, 1700 m, MNRJ 21249 . One female, OCEANPROF I, BC-SUL, # 84, Campos Basin , Rio de Janeiro, Brazil, 22°26′27.75″S, 39°58′51.65″W, 20 November 2002, 1050 m, MNRJ 21264 .

Etymology

The name bousfieldi is given in honour of Dr Edward Lloyd Bousfield (Canadian Museum of Nature) for his great contributions to amphipod taxonomy.

Type locality

Campos Basin, Rio de Janeiro, Brazil.

Diagnosis

Eyes absent. Mandibular palp very long, 5.5 times length of mandibular body. Gnathopod 1 carpus longer than propodus (1.2×), posterior margin densely setose, with posterodistal angle acute and slightly produced; propodus subtriangular, with both anterior and posterior margins setose. Gnathopod 2 strongly carpochelate; carpus massive, posterior margin setose, posterodistal angle produced into a long and acute process; propodus about two-thirds length of carpus, posterior margin setose, with a shallow middle excavation; dactylus as long as propodus, with a long seta on posterior margin. Uropod 1 long, peduncle with distoventral corona of spines, outer ramus with eight robust setae on both outer and inner margins, and one long robust apical seta; inner ramus one-quarter as long as outer ramus, with a single apical robust seta. Uropod 2 peduncle with distoventral corona of spines; outer ramus with two robust setae on outer margin, five robust setae on inner margin, and three distal robust setae; inner ramus one-third the length of outer ramus, with one distal robust seta. Uropod 3 peduncle with a distolateral tuft of setae; ramus without marginal robust setae, tip recurved with four spines and two setae. Telson subrectangular, wider than long, with acute process in middle of distal margin.

Description

Based on holotype male (3.8 mm), MNRJ 21257. Antennae missing. Head shorter than pereonites 1 and 2 together; anteroventral margin strongly recessed; eyes absent; lateral cephalic lobe acute. Epistome acute and turned upwards. Upper lip without distal notch. Mandibular palp very long, 5.5 times length of mandibular body, article 2 longer than article 3, with facial and marginal setae, article 3 with marginal and distal long setae. Maxilla 1 palp article 2 with four apical robust setae and four facial setae. Maxilla 2 outer plate broader than inner plate; inner plate with a row of facial setae. Maxilliped inner plate not extending beyond end of palp article 1; outer plate reaching one-third along palp article 2; article 4 with a long apical robust seta.

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 to each other, and shorter than coxae 1 and 2. Coxa 5 longer than coxae 1–4, with ten long setae on distal margin. Coxae 6 and 7 short, similar in shape to each other, shorter than the others. Gnathopod 1 basis moderately stout, posterior margin slightly convex, with four short setae; carpus longer than propodus (1.2×), posterior margin densely setose, with posterodistal angle acute and slightly produced; propodus subtriangular, with antero and postero margins setose; palm acute and minutely serrate; dactylus moderately stout, reaching end of palm. Gnathopod 2 strongly carpochelate; basis stout, posterior margin with five short setae; ischium and merus with a tuft of setae on posterodistal angle; carpus massive, posterior margin setose, posterodistal angle produced into a long acute process; propodus about two-thirds the length of carpus, posterior margin setose, with a shallow middle excavation; dactylus as long as propodus, with a long setae on posterior margin. Pereopods 3–7 missing.

Epimera 1–3 posteroventral margin rounded. Epimeron 3 posterior margin smooth. Uropod 1 long, peduncle with distoventral corona of spines, with two robust setae on outer margin; outer ramus with eight robust setae on both outer and inner margins, and one long robust apical seta; inner ramus one-quarter as long as outer ramus, with a single apical robust seta. Uropod 2 peduncle with distoventral corona of spines, with two robust setae on outer margin; outer ramus with two robust setae on outer margin, five robust setae on inner margin, and three distal robust setae; inner ramus one-third length of outer ramus, with one distal robust seta. Uropod 3 peduncle with a distolateral tuft of setae; ramus without marginal robust setae, tip recurved with four spines and two setae. Telson subrectangular, wider than long, with acute process in middle of distal margin.

Sexually dimorphic characters

The female differs from the male in having gnathopod 2 subchelate.

Tube

Unknown.

Remarks

Pseudericthonius bousfieldi sp. nov. is closely related to P. gaussi and P. hesperidesi in having the eyes absent, the carpus of gnathopod 2 of the male with the posterodistal process acute, the very reduced inner ramus of uropods 1 and 2, and the telson with a medial distal process. Nevertheless, P. bousfieldi sp. nov. has the peduncle of uropod 1 with two robust marginal setae; the inner ramus is one-quarter as long as the outer ramus, with a single robust distal seta; and the peduncle of uropod 3 has a subdistal tuft of setae. In addition, P. bousfieldi sp. nov. has the mandibular palp very long, about 5.5 times length of mandibular body; article 2 of the palp of maxilla 1 with four robust setae; article 2 of the maxilliped palp 4.2 times longer than wide; and the ramus of uropod 3 without robust setae and its tip recurved, with four spines.

Geographic distribution

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

Figures

Figure 28. Pseudericthonius bousfieldi sp. nov. Holotype, male (3.8 mm), OCEANPROF II – BC -NORTE #44, 01 July 2003, 749 m, MNRJ 21257.

Figure 29. Pseudericthonius bousfieldi sp. nov. Holotype, male (3.8 mm), OCEANPROF II – BC -NORTE #44, 01 July 2003, 749 m, MNRJ 21257.

Figure 30. Pseudericthonius bousfieldi sp. nov. Paratype female (3.5 mm), OCEANPROF II (BC SUL) #75, 18 June 2003, 1050 m, MNRJ 21250.