Bradyidius parabyssalis Markhaseva & Renz 2021, sp. nov.
Creators: name: Markhaseva, Elena L.
name: Renz, Jasmin
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Maxillopoda
Calanoida
Aetideidae
Bradyidius
Bradyidius parabyssalis

description: Bradyidius parabyssalis sp. nov.   
(Figs 5–6)  
 Holotype. Adult female, dissected, body length 3.25 mm. SMF 37264/1-3 (slides) and 37265 (vial) (Senckenberg). Collected above the sea bed at Sta. 533, in the Argentine Basin, 36° 00.20’ S 49° 01.96’ W, on 15 July 2009 by the DIVA 3 expedition, Meteor cruise ME 79–1, at a depth of 4602 m.   
 Paratype. One adult female, partly dissected, body length 3.10 mm (poor condition). ZIN, 91150. Collected above the sea bed at Sta. 676, Meteor Seamount 31° 44.58’ N 28° 12.26’ W, on 20 August 2009 by the DIVA 3 expedition, Meteor cruise ME 79–1, at a depth of 2560 m.   
 Additional material. One female (specimen 1), from the Pacific Ocean, body length 3.10 mm, collected above the sea bed in the Kurile-Kamchatka Trench, at Sta. 7–10 on 17 August 2012, 43°01.82’ N 152°58.55’ E, by the KuramBio 1 expedition, Sonne cruise SO 223, at a depth of 5223 m; 2 females (specimens 2 & 3), damaged, not measured, collected above the sea bed in the Kurile-Kamchatka Trench, at Sta. 12–4 on 31 August 2012, 39°42.78’ N 147°09.55’ E, by the KuramBio 1 expedition, Sonne cruise SO 223, at a depth of 5224 m.   
 Description. Female. Body length 3.10–3.25 mm. Prosome 3.7 times as long as urosome. Rostrum (Fig. 5A–D) two-pointed, divergent, excavation between points with two tubercles. General body view including the posterior corners length (Fig. 5E–F) as in B. abyssalis sp. nov. Genital double-somite symmetrical, in its anterior half with lateral swellings in dorsal view and dorsal swelling in lateral view (Fig. 5E–J). Spermathecae visible in holotype only and narrow-elongate and rounded in distal part (Fig. 5E–F). Caudal rami with 1 lateral seta, 1 ventral seta, and 4 terminal setae (Fig. 5E–F).   
 Antennule (Fig. 5K–L) totally retained in holotype only. Ancestral segment I retained in all specimens possesses 3 setae, the distal seta is the longest, proximal are shorter and nearly equal in length. Antennule of holotype reaching pedigerous somite 5, of 24 articulating segments setal numbers at the segments II–XXVIII as in B. abyssalis sp. nov.   
 Antenna (Fig. 6A), as in B. abyssalis sp. nov.   
 Mandible (Fig. 6B–D), as in B. abyssalis sp. nov., except for middle basal seta is longer.   
 Maxillule (Fig. 5M), maxilla and maxilliped as in B. abyssalis sp. nov.   
 Legs. P1–P4 (Fig.5N, 6E–G) as in B. abyssalis sp. nov., except for P4 coxa with lateral spinules.   
P5 absent.  
 Type locality. 36° 00.20’ S 49° 01.96’ W.   
 Etymology. The species name “ parabyssalis ” refers to the close similarity of the species to the above described species “ abyssalis ”.   
 Remarks. The species Bradyidius parabyssalis sp. nov. and B. abyssalis sp. nov. share the general habitus and the main morphological features of oral parts and swimming legs. B. parabyssalis sp. nov. differs from B. abyssalis sp. nov. in the following characters: 1) body size over 3.00 mm (vs 2.45–2.90 mm in B. abyssalis sp. nov.); 2) two tubercles present in excavation between rostral points (vs tubercles between rostral points absent in B. abyssalis sp. nov.); 3) antennule ancestral segment I with 3 setae and proximal setae about twice shorter than the distal seta (vs antennule ancestral segment I usually with 2 setae and proximal seta much more than twice shorter than distal seta in B. abyssalis sp. nov.); 4) mandible basal middle seta is well developed (vs this seta is vestigial in B. abyssalis sp. nov.), and 5) P4 coxa with lateral spinules (vs lateral spinules absent in B. abyssalis sp. nov.).   
 The combination of the following characters distinguish B. parabyssalis sp. nov. and B. abyssalis sp. nov. from other species of the genus: 1) the species are the only known representatives of Bradyidius, that possess 3 setae at the basis of the mandible (vs a single seta present in B. hirsutus and 2 setae in the other congeners); 2) both new species possess a long lateral spine on the P1 exopod segment 1 reaching, or exceeding the base of lateral spine at the exopod segment 2 and reaching, or exceeding the base of the second medial seta on the exopod segment 3 (this character is shared with B. luluae and B. spinifer, vs in the other congeners if this spine reaching, or exceeding the base of lateral spine at the exopod segment 2, then it is not reaching the base of the first medial seta on the exopod segment 3), and 3) both new species share the short posterior corners of the prosome, not reaching the middle length of the genital double-somite (this character is shared with B. curtus vs posterior corners of prosome reaching or exceeding the middle length, the posterior third, or posterior border of the genital double-somite in the other congeners) (Bradford, 1969, 1976; Grice, 1972; Markhaseva, 1996 and personal data herein).
description: Published as part of Markhaseva, Elena L. & Renz, Jasmin, 2021, 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, pp. 343-369 in Zootaxa 5004 (2) on pages 351-354, DOI: 10.11646/zootaxa.5004.2.5, http://zenodo.org/record/5757521