Carangolioides castellatus, Sittrop & Serejo & Souza-Filho & Senna, 2014

Sittrop, Daniela J. P., Serejo, Cristiana S., Souza-Filho, Jesser F. & Senna, André R., 2014, New genera and species of Urothoidae (Amphipoda) from the Brazilian deep sea, with the re-assignment of Pseudurothoe and Urothopsis to Phoxocephalopsidae, Journal of Natural History 49 (9), pp. 527-552 : 533-538

Carangolioides castellatus gen. nov. et sp. nov.

( Figures 1–3 )

Material examined

Holotype: sex unknown, 4.0 mm, Oceanprof I #74, 22°27 ′ 31 ″ S, 40°09 ′ 23 ″ W, 750 m, N/ R Astro Garoupa col., MNRJ 21439 .

Paratypes: 1 female, 5.4 mm, Oceanprof II #79, 22°20 ′ 22 ″ S, 40°01 ′ 24 ″ W, 750 m, N/ R Astro Garoupa col., MNRJ 21440 ; 2 specimens, sex unknown, 3.5 to 3.8 mm, Campos Basin , depth and collector unknown, MNRJ 18320 ; 1 female, 5.6 mm, Oceanprof I #59, 21°25 ′ 59 ″ S, 39°55 ′ 30 ″ W, 750 m, N/ R Astro Garoupa col., MNRJ 21441 ; 1 female, 6.0 mm, Oceanprof I #79, 22°19 ′ 50 ″ S, 40°00 ′ 35 ″ W, 750 m, N/ R Astro Garoupa col., MNRJ 21442 .

Etymology

The species name is an adjective, derived from the Latin word castellum, and refers to the posterior margin of the pereopod 5 basis, which is castellated.

Diagnosis

Rostrum present; head anteroventral angle rounded. Mandible lacinia mobilis reduced to a robust seta. Gnathopod 1 palm subequal in length to posterior margin of propodus. Gnathopod 2 palm shorter than posterior margin of propodus. Coxa 4 posterior margin straight. Pereopod 5 basis with posterior margin castelloserrate. Coxa 6 and 7 posteroventral margin lobate. Epimeral plate 3 posteroventral corner produced, apically rounded. Uropods 1 and 2 rami naked. Uropod 3 short and robust, outer ramus article 1 about twice as long as article 2.

Description

Head: eyes absent; rostrum absent; anteroventral corner rounded. Antenna 1 peduncular article 1 naked; primary flagellum 4-articulate, 1.25 times longer than peduncular article 3; accessory flagellum present, 3-articulate. Antenna 2 reaching end of peduncular article 2 of antenna 1; peduncular article 4 longer and stouter than article 5, both with two and three slender setae, respectively, on anterior margin, and with a row of eight and four robust setae, respectively, on posterior margin. Upper lip truncate distally. Mandible molar present, non-triturative; lacinia mobilis of both left and right simple and spiniform; accessory setal row absent; incisor process well developed of medium length and smooth; palp article 2 shorter than article 3 (0.6 times), with two marginal setae; article 3 with four distal long setae. Lower lip outer lobes with distolateral projection. Maxilla 1 inner plate with one subdistal seta and three distal pappose setae; outer plate with nine robust setae; article 1 of palp 1.8 times longer than article 2; article 2 with three distal pappose setae. Maxilla 2 outer plate wider than inner plate, both with long setae on distal margin. Maxilliped inner plate with three apical robust setae, outer plate reaching two-thirds of palp article 2, with seven marginal robust setae; palp article 2 expanded, 1.65 times longer than wide, inner distal margin produced, inner margin densely setose; article 3 expanded distally; article 4 0.65 times the length of article 3, with two slender distal setae.

Gnathopod 1 coxa rectangular, twice as long as wide, anteroventral angle rounded and posteroventral angle notched; basis long and slender, widened distally, anterior margin with four long setae, posterior margin with seven long setae; carpus subequal to propodus, posterior margin slightly lobate and densely setose; propodus with a seta on anterodistal angle; palm acute, sinuous, longer than posterior margin, with five long setae and one robust seta near palmar corner; dactylus moderately stout, longer than propodus. Gnathopod 2 coxa rectangular, about twice as long as wide, anteroventral and posteroventral angles rounded; basis long and slender, widened distally, posterior margin with 11 long setae; carpus slightly longer than propodus, posterior margin slightly lobate and densely setose; propodus outer surface not densely setose; palm almost transverse, shorter than outer margin, with one robust seta on palmar corner; dactylus moderately stout, subequal to propodus. Pereopod 3 coxa 1.6 times longer than wide; basis 1.8 times longer than wide; merus with a seta at anterodistal angle, shorter than propodus and carpus together; carpus robust 1.2 times longer than wide, with nine robust setae on posterior margin; propodus slightly more slender than carpus, with two rows of four robust setae on both inner and outer margins of posterior margin; dactylus short, 0.8 times propodus length. Pereopod 4 coxa 1.25 times longer than wide, posterior margin not excavate with posteroventral angle not produced; basis twice as long as wide, with six long setae posterior margin; merus shorter than propodus and carpus together; carpus robust, 1.3 times longer than wide, with six robust and three slender setae on posterior margin and a row of four facial robust setae; propodus slightly more slender than carpus, with two rows of four and three robust setae on both inner and outer margin of posterior margin, respectively; dactylus short, 0.8 times propodus length. Pereopod 5 coxa 1.2 times wider than long, with posteroventral lobe produced; basis ovate, as long as wide, posterior margin castelloserrate with three long setae; merus as long as wide, posterodistal angle with one seta; carpus 1.2 times longer than wide, anterior margin with two combs of robust setae (4–4), posterior margin with two combs of robust setae (4–6); propodus about as long as carpus, 1.7 times longer than wide, anterior margin with five long setae, posterodistal angle with one comb of three robust setae; dactylus styliform, 1.2 times longer than propodus. Pereopod 6 coxa slightly wider than long, with produced posteroventral lobe; basis ovate, 1.2 times longer than wide, posterior margin smooth with a row of four very long plumose facial setae; merus 1.3 times longer than wide, anterior margin with four slender setae, posterior margin with six slender setae; carpus 1.8 times longer than wide, anterior margin with two combs of slender setae (4–4); propodus shorter than carpus, 0.6 times longer than wide, anterior margin with two combs of slender setae (3–5); dactylus as long as propodus. Pereopod 7 coxa as long as wide, with posteroventral lobe produced; basis ovate, 1.25 times longer than wide, posterior margin sinuous lacking setae; merus slightly longer than wide, anterior margin with three slender setae, posterodistal angle with two slender setae; carpus 1.75 times longer than wide, anterior margin with one comb of four slender setae, posterior margin with two medial slender setae, posterodistal angle with five slender setae; propodus 1.4 times shorter than carpus, 1.6 times longer than wide, anterior margin with one medial comb of four slender setae, distal margin with six slender setae; dactylus subequal to propodus.

Epimeral plate 1: ventral margin with two long setae; posteroventral angle acute and slightly produced. Epimeral plate 2: ventral margin with one pappose seta; posteroventral angle acute and slightly produced. Epimeral plate 3: ventral margin lacking setae, posteroventral angle strongly produced into blunt process. Uropod 1: peduncle 1.2 times longer than rami, inner margin with one robust seta, anterodistal angle with one stout seta, posterodistal angle with robust setae; inner ramus subequal to outer ramus, both rami naked. Uropod 2: peduncle 0.7 times as long as rami, inner margin with one robust seta, inner distal angle with one stout seta, outer distal angle with robust setae; inner ramus subequal in length to outer ramus, both rami naked. Uropod 3 about 0.7 times the uropod 2 length and 0.6 times as long as uropod 1, peduncle as long as wide, and subequal in length to outer ramus, distomedial angle with one plumose seta, distolateral angle with one robust seta; rami foliaceous and stubby; inner ramus shorter than article 1 of outer ramus, with one long seta on inner margin, and one distal pappose seta; outer ramus 2-articulate, article 1 twice as long as article 2, distolateral angle with one robust seta; article 2 with two distal pappose setae. Telson deeply cleft (up to 70% length), lateral margins each with one short, slender seta; distal margin of each lobe weakly incised and with one robust seta.

Variation

The antenna 1 flagellum varies from 4- to 5-articulate. The distolateral corner of pereopod 6 basis has four to nine pappose setae. The epimeral plates 1 and 2 also present variation in number of setae on their ventral margins.

Remarks

Carangolioides castellatus gen. et sp. nov. is easily distinguished from C. hamatus gen. et sp. nov. by the following: the anteroventral unproduced angle of the head, in contrast to the acute projected angle observed in C. hamatus (which slightly overlaps the anteroventral margin of the head in the illustration); the unproduced posterior margin of coxa 4, in contrast to the sinuous coxa 4, with a posterodistal subacute projection in C. hamatus ; the posteroventral corner of epimeral plate 3 produced in an apically rounded process, versus the posteroventral corner produced in an acute upward hook, in C. hamatus ; and the lacinia mobilis reduced to a stout seta, in contrast to the well-developed and multicuspidate lacinia mobilis present in C. hamatus . In addition, the naked rami and sparsely armed peduncle of uropod 1 of C. castellatus differ markedly from the heavily armed uropod 1 of C. hamatus .

Geographic distribution

Known only from the type locality, Campos Basin , off Rio de Janeiro State coast .

Bathymetric range

Collected at 750 m depth.

Figures

Figure 1. Carangolioides castellatus gen. et sp. nov., holotype, sex unknown, 4.0 mm, 22°27′31″ S, 40°09′23″ W, 750 m depth, MNRJ 21439. Scale bars: 0.5 mm for Hd; 0.2 mm for A1–2, Md, Mp, UL; 0.1 mm for all others.

Figure 2. Carangolioides castellatus gen. et sp. nov., holotype, sex unknown, 4.0 mm, 22°27′31″ S, 40°09′23″ W, 750 m depth, MNRJ 21439. Scale bars: 0.1 mm for U3; 0.2 mm for U1–2; 0.5 mm for all others.

Figure 3. Carangolioides castellatus gen. et sp. nov., holotype, sex unknown, 4.0 mm, 22°27′31″ S, 40°09′23″ W, 750 m depth, MNRJ 21439. Scale bars: 0.5 mm.