Description of three new species of Bradyidius (Copepoda: Calanoida), the new aetideids from the deep Pacific Ocean, with notes on the genera Bradyidius and Aetideopsis Author Markhaseva, Elena L. Laboratory of Marine Research, Zoological Institute, Russian Academy of Sciences, Universitetskaya nab. 1, St. Petersburg 199034, Russia. Author Renz, Jasmin 0000-0002-2658-445X German Center for Marine Biodiversity Research (DZMB), Senckenberg am Meer, Martin-Luther-King Platz 3, 20146 Hamburg, Germany. jasmin. renz @ senckenberg. de; https: // orcid. org / 0000 - 0002 - 2658 - 445 X jasmin.renz@senckenberg.de text Zootaxa 2021 2021-07-20 5004 2 343 369 journal article 10.11646/zootaxa.5004.2.5 1175-5326 5757521 419EF04D-DC25-4A75-AC8A-6C5BAFFC07F1 Bradyidius abyssalis sp. nov. ( Figs 1–4 ) Holotype . Adult female, dissected, body length 2.80 mm . SMF 37266/1-4 (slides) and 37267 (vial) (Senckenberg). Collected above the sea bed at Sta. 636, Meteor Seamount, 29° 19.24’ N 28° 37.94’ W , on 18 August 2009 by the DIVA 3 expedition, Meteor cruise ME 79–1, at a depth of 4338 m . Paratype . One adult female, partly dissected, body length 2.45 mm . ZIN , 91149 the same label data as for holotype . Additional material . Four females from the Atlantic Ocean: 1 female , body length 2.90 mm , collected in the Guinea Basin , Sta. 64 (specimen 1), 15 March 2005 , 00°13.27’ S 002°29.91’ W , by the DIVA 2 expedition, Meteor cruise ME 63–2, at a depth of 5055 m ; 2 females , both body length 2.90 mm , collected in the Brazil Basin , Sta. 554 (specimen 2), 22 July 2009 , 26°34.70’ S 35°12.79’ W , by the DIVA 3 expedition, Meteor cruise ME 79–1, at a depth of 4485 m ; 1 female , body damaged, not measured, collected in the Brazil Basin , Sta. 561 (specimen 3), 23 July 2009 , 26°34.78’ S 35°13.90’ W , by the DIVA –3 expedition, Meteor cruise ME 79–1, at a depth of 4484 m ; Description. Female. Body length 2.45–2.90 mm . Prosome 3.20–3.35 times as long as urosome ( Fig. 1A–B ). Rostrum ( Fig. 1D–E ) two-pointed, divergent. Cephalosome and pedigerous somite 1 partly fused and pedigerous somites 4–5 separate; posterior corners of prosome prolonged into short points, covering the proximal third of genital double-somite ( Fig. 1A–B, F–G ). Urosome of 4 somites. Genital double-somite symmetrical, anterior third in dorsal view with lateral swellings and in lateral view with dorsal swelling ( Fig. 1F–G ). Spermathecae narrowelongate and oval-widened in the distal part ( Fig. 1F ). Caudal rami with 1 lateral seta, 1 ventral seta, and 4 terminal setae ( Fig. 1F–G ). Antennule ( Fig. 2A–D ) reaching pedigerous somite 4, of 24 articulating segments; armature as follows: I–2s ( holotype , paratype and additional specimens 2 and 3), or 3s in additional specimen 1, II–IV–6s+1ae, V –2s+1ae, VI –2s, VII –2s+1ae, VIII and IX–2s each, X–XI–4s+1ae, XII and XIII–2s each, XIV –1s+1? in holotype and 2s+1ae in paratype , XV–2s, XVI –2s+1ae, XVII to XX–2s each, XXI –2s in holotype and 2s+1ae in paratype , XXII and XXIII–1s each, XXIV –2s+1ae, XXV –XXVI–2s each, XXVII –XXVIII–4s+1ae in holotype and 5s+1ae in paratype . Antenna ( Fig. 2E–F ), coxa with 1 seta, basis with 2 setae; exopod of 8 segments, setation formula 1,1-1-1, 1, 1, 1, 1, 1, and 3 setae, endopod segment 1 with 2 setae, endopod segment 2 with 8 + 7 setae. Mandible ( Fig. 2G–I ), gnathobase with 7 teeth; basis with 3 setae, middle seta small; exopod 5-segmented with 1, 1, 1, 1, and 2 setae; endopod segment 1 with 3 setae, segment 2 with 9+2 setae. Maxillule ( Fig. 3A–B ), praecoxal arthrite with 9 terminal spiniform setae, 4 posterior and 1 anterior setae, coxal endite with 5 setae; coxal epipodite with 7 long+2 short setae; proximal basal endite with 4 setae, tubercle with pore and small denticles along the distal border present, distal basal endite with 5 setae; endopod with 15 setae (16 setae in paratype ); exopod with 10 setae. FIGURE 1. Bradyidius abyssalis sp. nov. Female, holotype. A, habitus, dorsal view; B, habitus, lateral view; C, prosome, anterior dorsal view; D, prosome anterior and rostrum, lateral view; E, rostrum; F, posterior prosome and urosome, lateral view; G, posterior prosome and urosome, dorsal view; H, P1. Scale bars: A–B 0.5 mm, C–H 0.1 mm. FIGURE 2 . Bradyidius abyssalis sp. nov. Female, holotype. A, antennule, ancestral segments I–XI; B, antennule, ancestral segments XII–XIX; C, antennule, ancestral segments XX–XXVI; D, antennule, ancestral segments XXVII–XXVIII; E, antenna exopod; F, antenna, coxa, basis and endopod; G, mandible, palp, endopod segment 1; H, mandible, endopod segment 2; I, mandible, gnathobase. Scale bars 0.1 mm. FIGURE 3 . Bradyidius abyssalis sp. nov. Female, holotype. A, maxillule; B, maxillule, endopod segments 1–3; C, maxilla, endopod not figured, scar indicates that a setal element was broken at coxal endite; D–E, enditic lobe of endopod and endopod in different views. Scale bars 0.1 mm. FIGURE 4. Bradyidius abyssalis sp. nov. Female, holotype. A, maxilliped, syncoxa; B, maxilliped, basis and endopod segment 1; C, maxilliped, endopod, terminal setae of endopod not figured; D, maxilliped, endopod segments 5–6; E, P2; F, P3; G, P4. Scale bars 0.1 mm. Maxilla ( Fig. 3C–E ), praecoxal to basal endites with 3 setae each, all endites decorated with spinules; enditiclike lobe of proximal endopod segment with 3 setal elements, two of them thicker, spine-like; endopod with 9 (2+2+2+3) setae. Maxilliped ( Fig. 4A–D ), syncoxa with 1 seta on proximal praecoxal endite, 2 setae on middle praecoxal endite and 3 setae on distal praecoxal endite; coxal lobe with 3 setae and tubercle with a deep notch (arrowed at Fig. 4A ). Basis with 3 setae. Endopod 6-segmented with 2, 4, 4, 3, 3+1, and 4 setae, first segment very small and fused to basis. Legs. P1 ( Fig. 1H ), coxa with lateral spinules; basis with medial distal seta curved with setules; endopod 1-segmented with lateral lobe, its lateral margin with spinules and anterior surface with distal spinules; exopod segment 1 with lateral setiform spine and segments 2 and 3 with 1 lateral spine each; lateral setiform spine of exopod segment 1 exceeding the base of the lateral spine at the exopod segment 2 and nearly reaching the base of exopod segment 3 third medial seta. P2–P4 ( Fig. 4E–G ), coxa with 1 medial seta, P2–P3 coxa with lateral spinules, at P4 coxa lateral spinules absent; basis without seta; endopod 2-segmented in P2, 3-segmented in P3–P4; posterior surface spinules present on P2 endopod segment 2 and P3–P4 endopod segments 2 and 3. P5 absent. Male unknown. Type locality . 29° 19.24’ N 28° 37.94’ W . Etymology. The species name “ abyssalis ” refers to the depth of the species’ habitat within the Atlantic Ocean. Remarks. Differences from known congers are given in the remarks of the next species.