Cheirimedon foscae, Siqueira, Silvana Gomes L. & Serejo, Cristiana S., 2014

Siqueira, Silvana Gomes L. & Serejo, Cristiana S., 2014, Cheirimedon foscae sp. nov. (Amphipoda: Lysianassidae: Tryphosinae) from the deep sea Campos Basin, Southwestern Atlantic Ocean, Zootaxa 3873 (2), pp. 145-154 : 146-148

Cheirimedon foscae sp. nov.

Figures 1–4

Material examined: OCEANPROF— Holotype: female, 5.45 mm, # 54, 21º57.19'S, 39º 56.07'W, 698 m, 29th June, 2003 ( MNRJ 21062). Paratypes: 1 female, # 51, 22º4.72'S, 39º 49.15'W, 24th November, 2002 ( MNRJ 24110). HABITAT — 1 juvenile, #E-08, 22º33.65'S, 40º9.07'W, 975.2 m, 11th May, 2008 ( MNRJ 24111); 1 female, # G-08, 22º7.33'S, 39º52.37'W, 992.6 m, 13th May, 2008 ( MNRJ 24112); 1 female, # H-09, 21º39.36'S, 39º 52.97'W, 1293.2 m, 13th May, 2008 ( MNRJ 21413); 1 juvenile, #CANG-09, 21º54.71'S, 39º50.57'W, 1311.9 m, 28th May, 2008 ( MNRJ 24114); 1 juvenile, # A-06, 23º 37.95'S, 41º19.71'W, 390.6 m, 03th July, 2008 ( MNRJ 24115); 1 juvenile, # D-06, 22º 33.56'S, 40º26.671'W, 396.2 m, 11th July, 2008 ( MNRJ 24116); 1 juvenile, # F-07, 22º 20.84'S, 40º 2.97'W, 705.3 m, 0 7th July, 2008 ( MNRJ 27117). MAPEM —two females, 21º8.36'S, 40º10.27'W, 902 m ( MZUSP 27231); 1 female, 21º8.32'S, 40º10.30'W, 902 m ( MZUSP 27233); 1 female, 21º8.34'S, 40º10.21'W, 902 m ( MZUSP 27234); 2 females and 1 juvenile, 21º8.29'S, 40º10.30'W, 902 m ( MZUSP 27239); 1 juvenile 21º8.25'S, 40º10.27'W, 902 m ( MZUSP 27240); 1 juvenile 21º8.28'S, 40º10.31'W, 902 m ( MZUSP 27246); 2 females and 1 juvenile 21º8.34'S, 40º10.10'W, 902 m ( MZUSP 27248); 1 female and 1 juvenile, 21º8.48'S, 40º10.36'W, 902 m ( MZUSP 27251); 2 females 21º8.07'S, 40º10.27'W, 902 m ( MZUSP 27254); 1 female 21º8.47'S, 40º10.02'W, 902 m ( MZUSP 27255); 1 female 21º8.10'S, 40º10.41'W, 902 m ( MZUSP 27258); 1 female 21º8.17'S, 40º10.27'W, 902 m ( MZUSP 27403).

Diagnosis: Eyes absent; palp of maxilla 1 with six distal robust setae on right side and seven distal robust setae on the left side; gnathopod 1, propodus 1.2 x longer than wide; dactyl longer than palm; anterior margin of basis of pereopods 6–7 with row of setules; epimeron 3 slightly produced; telson cleft about 3/4 of its length, with one distal robust seta and two sub-marginal setae at each lobe.

Description: Female holotype, 5.45 mm. Head, lateral cephalic lobe large and pointed; eyes absent. Antenna 1, peduncular article 1 robust, length subequal to width; peduncular articles 2 and 3 very small; accessory flagellum short, 0.5x primary flagellum, 3-articulate, article 1 long, 0.7x article 2, article 3 very short; primary flagellum 8- articulate, article 1 with callynophore, length 3.0x the width. Antenna 2, peduncular article 2 and 3 short, 4 and 5 enlongate and subequal in length; flagellum 10-articulate, article 10 very small. Upper lip, anterior edge slightly projecting in front of epistomal margin. Mandibles, incisors symmetrical, large, with straight margins, left lacinia mobilis present, accessory setal row with 3 curve serrulate setae; molar triturative; palp 1.5x mandible length; article 1 short, length subequal to width; article 2, 1.3x article 3, with 6 slender serrate setae on apical posterior margin; article 3 with 12 slender serrate setae and setose on posterior margin. Maxilla 1, inner plate with 2 pappose setae at apex; outer plate broad with 11 setal-teeth in 7/4 arrangement; palp large, 2-articulate, article 1 short, 0.3x length article 2, article 2 with 2 slender serrate setae on subapical margin and 7 robust setae on left side and 6 robust setae on right side. Maxilla 2, inner and outer plates slender; inner plate length 0.8x outer plate, with 12 slender serrate setae on apical margin and 1 strong pappose seta on inner distal margin; outer plate with 12 serrate setae on distoapical margin. Maxilliped, inner plate length 3.2x width reaching beyond article 1 of palp, slightly tapering on apex with 3 short robust setae and 2 slender pappose setae, medioapical margin with 6 slender pappose setae; outer plate broad, suboval, distal margin reaching half article 3 of palp with 8 robust setae of decreasing size from apex to the margin; palp 4-articulate, article 1 0.72x length article 2 with seta on posteroapical margin, article 2 length 1.3x article 3 with 13 simple slender setae on medial margin, article 3 subovate, medial margin with 6 slender setae, one on apex and 4 on posteroapical margin, article 4 length 1.0x article 3, with apical nail.

Gnathopod 1, coxa suboval, length 2.35x width, broadly rounded anteroventrally; basis subrectangular, width 0.27x length with slender setae on anterior margin; isquium short, subequal in length to merus; carpus characteristic in form, subtriangular, slightly lobate, 0.3x length of propodus; propodus subtriangular, 1.2x longer than wide, anterodistal margin with 6 slender simple setae, posterior margin with row of setules, palm crenate and setose, palmar corner defined by 2 robust setae; dactylus slender, distinctly longer than palm. Gnathopod 2, coxa large, subrectangular, width 0.4x length, gradually broadened distally; basis linear, elongate; ischium elongate, subequal in length to carpus; merus subovate with small setae on posterior margin and one distal seta; carpus broadly convex anteriorly and setose, posterior margin with patch of comb scales distally; propodus subovate, length 0.66x carpus, with 6 serrate setae on anterodistal corner and 5 serrate setae on posterior margin, palm transverse with minute setae; dactylus short, smaller than palm. Pereopod 3, coxa similar in shape of that of gnathopod 2; basis subrectangular, width 0.3x length with tiny setae on anterior margin; isquium short, length subequal width; merus subrectangular, length 2.0x carpus, posterior margin setose; carpus length 0.6x propodus, posterior margin setose; propodus elongate, width 0.2x length, with 3 pairs of slender and small robust setae on posterior margin. Pereopod 4, coxa broader (x1.33) than that of pereopod 3, with small posterodistal lobe. Pereopod 5, coxa large, width 0.8x length, anterior lobe slightly broader than posterior lobe; basis subovate, width 0.63x length, posterior margin slightly serrate with small setae, posterodistal lobe reaching merus and anterior margin with small robust setae; isquium short, width subequal length, with one robust seta anterodistally; merus expanded posteriorly with 4 robust setae, anterior margin with 2 or 3 slender setae; carpus width 0.63x length with 4 long setae and small robust setae anteriorly; propodus elongate, width 0.25x length, with 3 pairs of slender and robust setae on anterior margin; dactylus slender, length 0.75x propodus. Pereopod 6, coxa subquadrangular, width 0.75x length, bilobate, posterior lobe broader than anterior, basis similar to pereopod 5, but posterodistal lobe small, medioanterior margin with setule row; isquium width 0.63x length with one slender seta and 1 robust seta on anterodistal corner; merus subrectangular length 1.0x carpus, anterior margin with 4 set of slender setae and small robust setae; carpus length 0.71x propodus, margins similar to merus; propodus elongate width 0.17x length, anterior margin similar to merus; dactylus slender length 0.57x propodus. Pereopod 7, coxa non lobate, basis larger than basis of pereopod 6, posterior margin serrate and with small setae; medioanterior margin with setule row longer than that of pereopod 6; merus length 0.6x carpus.

Epimeron 1, anteroventral corner minutely produced and posteroventral corner round. Epimeron 2, posteroventral corner minutely produced. Epimeron 3, posteroventral corner produced. Urosomite 1, slightly carinate with a setule row on dorsal margin. Uropod 1, peduncle subrectangular, 1.33x outer ramus, with 2 rows of 7 and 3 dorsolateral robust setae respectively, and 2 apicolateral robust setae; outer ramus subequal in length to inner, with 3 robust setae; inner ramus with 4 robust setae. Uropod 2, peduncle subequal in length to outer ramus, with 2 rows of 4 and 1 dorsolateral robust setae respectively and 2 apicolateral setae; rami with subapical nails, outer ramus length 0.75 inner ramus, with row of 4 robust setae, inner ramus with 3 robust setae. Uropod 3, peduncle length 2.0x outer ramus, with 3 distoventral and 1 distolateral robust setae; outer ramus bi-articulate, article 1 elongate 2.0x length of article 2, with 2 distal robust setae. Telson, width 0.54x length, cleft about 3/4 of its length, each lobe with one pair of plumose setae and a robust seta on mediodorsal surface, a single sub-distal robust seta and a large robust seta at apex.

Male: Unknown.

Remarks: Cheirimedon foscae sp. nov. is closest to C. crenatipalmatus and C. cansada in the absence of eyes and the shape of lateral cephalic lobe. The new species can be distinguished by these two species by the shape of propodus and length of gnathopod 1 dactylus (see key). Moreover, the maxilla 1 presents 6 distal robust setae on right palp and 7 distal robust setae on the left. In the original description of C. crenatipalmatus, Stebbing (1888) described 9 robust setae for the right maxilla and 12 robust setae for the left one. Barnard (1961) does not describe this character for C. cansada .

Figures

FIGURE 1. Cheirimedon foscae sp. nov., holotype, female, 5.45 mm, Campos Basin, RJ, Brazil, MNRJ 21062. Scale bar: 1.0 mm.

FIGURE 2. Cheirimedon foscae sp. nov., holotype, female, 5.45 mm, Campos Basin, RJ, Brazil, MNRJ 21062. Scale bar: 0.1 mm.

FIGURE 3. Cheirimedon foscae sp. nov. holotype, female, 5.45 mm, Campos Basin, RJ, Brazil, MNRJ 21062. Scale bar: 0.5 mm.

FIGURE 4. Cheirimedon foscae sp. nov. holotype, female, 5.45 mm, Campos Basin, RJ, Brazil, MNRJ 21062. Scale bar: 0.5 mm