Caudacalanus mirus, Markhaseva, Elena L. & Schulz, Knud, 2008

Markhaseva, Elena L. & Schulz, Knud, 2008, Caudacalanus (Copepoda, Calanoida): a new benthopelagic genus from the abyss of the tropical South Atlantic and Southern Ocean *, Zootaxa 1866, pp. 277-289 : 280-287

publication ID	https://doi.org/ 10.5281/zenodo.183714
DOI	https://doi.org/10.5281/zenodo.6227774
persistent identifier	https://treatment.plazi.org/id/EB55880C-FFE7-FFFF-FF4B-0310FD48A006
treatment provided by	Plazi
scientific name	Caudacalanus mirus
status	sp. nov.

Treatment

Caudacalanus mirus sp. nov.

( Figs 1–3 View FIGURE 1 )

Holotype. Dissected adult female ( ZMH Reg. no. K–41255), body length 2.70 mm. Collected Southern Ocean, 60º38’S 53º57’W, RV Polarstern (ANDEEP I), 30 January 2002, above the seabed at 2893– 2889 m. Paratype. Dissected adult female ( ZMH Reg. no. K–41256), body length 2.80 mm. Collected Southern Ocean, 65º19’S 51º31’W, RV Polarstern (ANDEEP II), 0 5 March 2002, above the seabed at 3050 m.

The holotype and paratype are deposited at the Zoological Museum Hamburg, University of Hamburg ( ZMH).

Description. Female: total length 2.70–2.80 mm (n=2). Prosome 1.3–1.5 times as long as urosome. Rostrum as an elongated cone ( Fig. 1 View FIGURE 1 C–D). Posterior corners of prosome as short rounded lobes ( Fig. 1 View FIGURE 1 A–B, I). Genital double somite symmetrical ( Fig. 1 View FIGURE 1 H–I, K). Caudal rami asymmetrical; right ramus nearly twice as long and wide as left; both rami with 4 terminal setae; right ramus with a small mediodorsal seta, ventral seta lacking; left ramus with a small medioventral seta, dorsal seta lacking ( Fig. 1 View FIGURE 1 B, F–G).

Antennule extending to posterior border of prosome somite 3 ( Fig. 3 View FIGURE 3 A–D), 25segmented, segments 24– 25 incompletely separate, armature as follows: I–1 s, II– IV–6 s + 1ae, V–2 s, VI–2 s, VII–2 s + 1ae, VIII–2 s, IX– 2 s, X– XI–4 s + 1ae, XII–1 s, XIII–2s, XIV–2s, XV–1s, XVI–2s, XVII–1s, XVIII–1s, XIX–1s, XX–1s, XXI– 2s, XXII– 1s, XXIII–1s, XXIV–2s, XXV–2s, XXVI–2s, XXVII–2s, XXVIII–3s+ 1ae.

Antenna ( Fig. 2 A), coxa with 1 seta; basis with 2 setae; first endopodal segment with 1 seta (2 in paratype), second with 7 (8 in paratype) and 6 setae (1314 setae in total), endopod about 1.8 times as long as exopod; exopod 8segmented with 0, 1, 1, 1, 1, 1, 1 and 3 setae, second segment complex of 3 ancestral segments with 0–0–1 setae.

Mandible ( Fig. 2 B–C), gnathobase with 4 large teeth and seta; basis with 2 setae; endopod segment 1 without setae, segment 2 with 8 setae; exopod 5segmented with 1, 1, 1, 1 and 2 setae.

Maxillule ( Fig. 2 D), praecoxal arthrite with 7 terminal spines (8 spines in paratype) and 2 posterior setae; coxal epipodite with 1 seta; coxal endite with 4 setae, 2 long and strongly sclerotized; proximal basal and distal basal endites reduced; endopod fused to exopod, without setae.

Maxilla ( Fig. 2 E), praecoxal and coxal endites with 2 setae each; basis without setae; endopod 3segmented with 1, 1 and 2 setae.

Maxilliped ( Fig. 2 F), syncoxa with 2 setae on distal praecoxal endite, 1 seta longer than basis plus endopod and curved in terminal part; coxal endite with 1 seta. Basis with 1 medial seta. Endopod 3segmented with 1, 1, and 1 setae.

P1 ( Fig. 3 View FIGURE 3 E–F), coxa without seta; basis without a medial or lateral seta; endopod 1segmented with 3 medial and 2 terminal setae, lacking lateral lobe, distal lateral corner smoothly rounded, not reaching suture between exopod segments 2 and 3; exopod segment 1 without setae, exopod segment 2 with 1 medial seta, lateral spine lacking; exopod segment 3 with 4 medial setae, 1 terminal and 1 lateral spine.

P2 ( Fig. 3 View FIGURE 3 G), coxa with seta, basis without seta; endopod 2segmented, segment 1 with 1 medial seta, segment 2 with 2 medial, 2 terminal and 1 lateral setae; exopod 3segmented, segments 1 and 2 with 1 medial seta and 1 lateral spine; segment 3 with 5 medial setae, 1 terminal and 3 lateral spines; terminal spine about as long as exopod segment 3.

P3–P4 ( Fig. 3 View FIGURE 3 H–I), coxa with seta; basis without seta; endopod segments 1 and 2 with 1 medial seta each, segment 3 with 2 medial, 2 terminal and 2 lateral setae. Exopod as in P2. P3 terminal spine 0.8 times as long as exopod segment 3; P4 terminal spine 0.7 times as long as exopod segment 3.

Etymology. The specific name (from Latin mirus meaning wonderful, strange) refers to the exceptional shape of the caudal rami. It is an adjective agreeing in gender with the (masculine) generic name.

Caudacalanus vicinus sp. nov. ( Figs 4–5 View FIGURE 4 View FIGURE 5 )

Holotype. Dissected adult female ( ZMH Reg. no. K–41257), body length 2.00 mm. Collected Southern Ocean, 65º00’S 43º01’W, RV Polarstern (ANDEEP II), 11 March 2002, above the seabed at 4679– 4678 m. Paratypes. Dissected adult female ( ZMH Reg. no. K–41258), body length 1.85 mm. Collected Southern Ocean, 60º38’S 53º57’W, RV Polarstern (ANDEEP I), 30 January 2002, above the seabed at 2893– 2889 m; undissected adult female ( ZIN Reg. no 91088), body length 1.80 mm, same collection data as for another paratype.

The holotype and 1 paratype are deposited at the Zoological Museum Hamburg, University of Hamburg ( ZMH); 1 paratype is deposited at the Zoological Institute, Russian Academy of Sciences, St. Petersburg ( ZIN).

Additional material. Adult female, damaged, not measured. Collected Southern Ocean, 59º40’S 57º37’W, RV Polarstern (ANDEEP I), 27 January 2002, above the seabed at 3683– 3680 m. Adult female, body length 1.80 mm. Collected southeastern Atlantic, 17º06’S 04º41’W, FS Meteor (DIVA1), 25 July 2000, above the seabed at 5415 m.

Description. Female: total length 1.80–2.00 mm (n=4). Prosome 1.8–2.0 times longer than urosome. Rostrum as elongated cone ( Fig. 4 View FIGURE 4 C). Posterior corners of prosome as short rounded lobes ( Fig. 4 View FIGURE 4 B). Genital double somite symmetrical ( Fig. 4 View FIGURE 4 D). Caudal rami asymmetrical; right ramus nearly twice as long and wide as left; both rami with 4 terminal setae; right ramus with a dorsal seta, ventral seta lacking, left ramus with a ventral seta, dorsal seta lacking ( Fig. 4 View FIGURE 4 A–B, D–F).

Antennule exceeding posterior border of prosome somite 3, or as long as prosome ( Fig. 4 View FIGURE 4 G–K), 25segmented, armature as follows: I–1 s, II– IV–6 s + 1ae, V–2 s, VI–2 s, VII–2 s + 1ae, VIII–2 s, IX–2 s, X– XI–4 s +?, XII–1 s, XIII–2s, XIV–2s, XV–1s, XVI–2s, XVII–1s, XVIII–1s, XIX–1s, XX–1s, XXI–2s, XXII– 1s, XXIII– 1s, XXIV–2s, XXV–2s, XXVI–2s, XXVII–2s, XXVIII–3s+ 1ae.

Antenna ( Fig. 5 View FIGURE 5 A), coxa with 1 seta; basis with 2 setae; first endopodal segment with 2 setae, second with 7 and 6 setae (13 setae in total), endopod about 1.6 times as long as exopod; exopod 8segmented with 0, 1, 1, 1, 1, 1, 1 and 3 setae, second segment complex of 3 ancestral segments with 0–0–1 setae.

Mandible ( Fig. 5 View FIGURE 5 B–C), gnathobase with 4 large teeth and seta; basis with 2 setae; endopod segment 1 without setae, segment 2 with 8 setae; exopod 5segmented with 1, 1, 1, 1 and 2 setae.

Maxillule ( Fig. 5 View FIGURE 5 D), praecoxal arthrite with 8 terminal spines and 3 dorsal setae; coxal epipodite with 6–7 setae; coxal endite with 3 setae, of them 2 long and strongly sclerotized; proximal basal and distal basal endites reduced; endopod separate from exopod without setae, exopod with 1 seta.

Maxilla ( Fig. 5 View FIGURE 5 E), proximal praecoxal endite with 2 setae and small attenuation; distal praecoxal and coxal endites with 2 setae each; basis without setae; endopod 3segmented with 1, 1 and 2 setae.

Maxilliped ( Fig. 5 View FIGURE 5 F), syncoxa with 2 unequal setae on distal praecoxal lobe, 1 seta curved in distal part, longer than basis plus endopod; coxal lobe with 1 seta; basis with 1 medial seta; endopod 3segmented with 1, 1, and 2 (1 long and 1 short) setae.

P1 ( Fig. 5 View FIGURE 5 G), coxa without seta; basis without a medial or lateral seta; endopod 1segmented, with 3 medial and 2 terminal setae, without lateral lobe; distal lateral corner triangular, slightly exceeding suture line between exopod segments 2 and 3; exopod segment 1 without setae, exopod segment 2 with 1 medial seta, lateral spine lacking, exopod segment 3 with 4 medial setae, 1 terminal and 1 lateral spine.

P2–P4 ( Fig. 4 View FIGURE 4 L–N) as in C. mirus except for P2–P3 terminal spines longer: P2 terminal spine about 1.2 times as long as exopod segment 3, P3 terminal spine about as long as exopod segment 3. P4 terminal spine 0.7 times as long as exopod segment 3.

Etymology. The specific name (from Latin vicinus meaning similar) refers to the general similarity of this species with the type species of the genus. The name is an adjective agreeing in gender with the (masculine) generic name.

Remarks. Caudacalanus vicinus differs from C. mirus in: i) smaller size (1.80–2.00 mm vs. 2.70–2.80 mm in C. mirus ); ii) praecoxal arthrite of maxillule having 3 dorsal setae (2 setae in C. mirus ); iii) coxal epipodite of maxillule with 6–7 setae (l seta in C. mirus ); iv) coxal endite of maxillule with 3 setae (4 setae in C. mirus ); v) endopod of maxillule separate from exopod and lacking any seta; exopod with 1 seta (fused to exopod and without setae in C. mirus ); vi) maxilla proximal praecoxal endite with 2 setae and some attenuation (antennuation absent in C. mirus ); vii) maxillipedal endopod segment 3 with 2 setae (1 seta in C. mirus ); viii) P1 endopod slightly exceeding suture between exopod segments 2 and 3 (vs. endopod not reaching suture between exopod segments 2 and 3 in C. mirus ), with distal lateral corner triangular (smoothly rounded in C. mirus ); ix) P2 terminal spine about 1.2 times as long as exopod segment 3 (in C. mirus , terminal spine about as long as exopod segment 3); x) P3 terminal spine about as long as exopod segment 3 (in C. mirus , P3 terminal spine 0.8 times as long as exopod segment 3).