Bradyetes paramatthei Markhaseva & Petrov & Renz 2020, sp. nov.

Bradyetes paramatthei sp. nov.

(Figs 5–8)

Holotype. Adult female, dissected, body length 2.10 mm. ZMH 45138. Collected above the sea bed in the Kurile- Kamchatka Trench at Sta. 2–10, 46° 14.76’ N 155° 32.81’ E, on 3 August 2012 by the KuramBio 1 expedition, Sonne cruise SO 223, at depths between 4859 and 4865 m.

Paratypes. 5 adult females, partly dissected, body length 2.20, 2.20, 2.20, 2.30 and 2.30 mm. SMF 37208– 37212, collected above the sea bed in the Kurile-Kamchatka Trench, by the KuramBio 1 expedition, Sonne cruise SO 223 at Sta. 9–12 on 24 August 2012, 40°34.49’ N 150°59.85’ E, at depths between 5399 and 5392 m; 2 adult females, 1 in poor condition, body length 2.00, 2.15 mm, ZIN 91147, Sta. 11–12, 31 August 2012, 40°12.32 ‘ N 148° 05.73’ E, at depths between 5350 to 5348 m.

Type locality. 46°14.77’ N 155°32.79’ E.

Additional material. Four females from the Atlantic Ocean: 1 female, body length 2.15 mm, collected in the Angola Basin, Sta. 348, 27 July 2000, 16°16.98’ S 005°27.27’ E, by the DIVA–1 expedition, Meteor cruise ME 48–1, at a depth of 5390 m; 2 females collected in the Guinea Basin by the DIVA–2 expedition, Meteor cruise ME 63–2 from 2 stations – 1 female, body damaged, not measured, Sta. 64–5, 15 March 2005, 00°13.27’ S 002°29.91’ W, depth 5055 m and 1 female, body length 2.05 mm, Sta. 89–6, 20 March 2005, 00°45.30’ S 005°35.00’ W, depth 5154 m; 1 female, body length 1.90 mm, collected at Meteor Seamount, Sta. 636, 18 August 2009, 29°19.24’ N 28°37.94’ E, by the DIVA–3 expedition, Meteor cruise ME 79–1, at a depth of 4338 m. One female from the Pacific Ocean, body length not measured, collected above the sea bed in the Kurile-Kamchatka Trench, at Sta. 7–10 on 17 August 2012, 40°01.82’ N 152°58.55’ E, by the KuramBio 1 expedition, Sonne cruise SO 223, at depths between 5223 and 5221 m.

Description. Female. Body length 1.90–2.30 mm. Prosome 2.7–3.3 times as long as urosome (Fig. 5 A–B). Rostrum as a significantly reduced blunt plate (Fig. 5C). Cephalosome and pedigerous somite 1 and pedigerous somites 4–5 incompletely separate; posterior corners oval-triangular in dorsal view; rounded in lateral view (Fig. 5 A–B, E–H). Urosome of 4 somites (Fig. 5 A–B). Genital double somite globular shape. Spermathecae large, round to oval round with very narrow duct leading to the genital atrium (Fig. 5B, F–H). Caudal rami with 1 lateral seta, 1 ventral seta, and 4 terminal setae (Fig. 5D).

Antennule (Fig. 5 J–L) reaching pedigerous somite 3, of 24 articulating segments; armature as follows: I–3s, II–IV–6s+1ae (ae absent in holotype), V–2s+1ae, VI–2s, VII–2s+1ae, VIII and IX–2s each, X–XI–4s+1ae, XII and XIII–2s each, XIV–2s+1ae, XV–2s, XVI–2s+1ae, XVII to XXI–2s each, XXII and XXIII–1s each, XXIV–XXVI– 2s each, XXVII–XXVIII–5s+1ae, aestethasc long, nearly as long as 3 preceding segments together.

Antenna (Fig. 6 A–C), coxa with 1 seta, basis with 2 setae; exopod of 8 segments, setation formula 1?0?1?1, 1, 1, 1, 1, 1, and 3 setae (uncertain whether proximal Enp 1 and 2, or Enp 2 and 4 are fused), all terminal setae long, of nearly the same length; first endopodal segment with 2 setae, second with 8–9 + 7 setae.

Mandible (Fig. 6 D–E), gnathobase with 4 large and 4 small teeth near dorsal seta; basis with 2 setae; exopod 5-segmented with 1, 1, 1, 1, and 2 setae; endopod segment 1 with 2 setae, segment 2 with 9+1, or 9 setae in paratype.

Maxillule (Fig. 6F), praecoxal arthrite with 9 terminal, 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, distal basal endite with 5 setae; endopod with 16 setae; exopod with 9–10 setae.

Maxilla (Fig. 7 A–B), praecoxal to basal endites with 3 setae each, all endites decorated with denticles; enditiclike lobe of proximal endopod segment with 3 setal elements, two thicker, spine-like; endopod with 9 (2+2+2+3) setae.

Maxilliped (Fig. 7 C–E), 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 conical tubercle. 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. 6G), coxa with lateral spinules; basis with small lateral spinule distally and medial distal seta curved with setules; endopod 1-segmented with lateral lobe, its lateral margin with spinules, anterior segment surface with distal spinules; exopod segments 1 to 3 with 1 lateral spine each; spine of exopod segment 1 usually exceeding base of segment 2 lateral spine, sometimes, reaching base of segment 2 lateral spine. P2–P4 (Fig. 8 A–C), coxa with 1 medial seta and medial spinules; basis without seta; endopod 2-segmented in P2, 3-segmented in P3–P4; posterior surface spinules present on P2 endopod segment 2 (nude in holotype), P3 endopod segment 3, and P4 endopod segments 2–3 (nude in holotype); exopods 3-segmented. P5 absent.

Male unknown.

Etymology. The species name “ paramatthei ” refers to a close relation of the species to Bradyetes matthei Johannessen, 1976.

Remarks. The new species is closely related to B. matthei and shares with this species a significant number of morphological features (Table 3), but differs from B. matthei in the shape of the posterior corners of Pd5, which are rounded (vs drawn out into the triangular points in B. matthei) and in the armament of the proximal segment of the antennal exopod, which bears a seta (vs seta absent in B. matthei).

While Bradyetes paramatthei sp. nov. and B. matthei both inhabit the near-bottom biotope, they are widely separated geographically and live in distant depth zones. Bradyetes matthei is recorded only from its type locality (Fensfjord, about 60° N 05° E) at depths between 548 and 580 m (Johannessen 1976, Markhaseva 1996), whereas the new species was collected at abyssal depths between 4338 and 5399 m in the North and South Atlantic Ocean (several localities between 29° N and 16° S: Angola and Guinea basins, Meteor Seamount) and in the Pacific Ocean (Kurile-Kamchatka Trench).