taxonID	type	description	language	source
4605AB40F9385863B2F8385C952AFA2E.taxon	description	Figs 1, 2, 3, 9 E – H, 10 B – D	en	Ng, Peter K. L., Sidabalok, Conni M., Nguyen, Thanh Son (2025): A new species of supergiant Bathynomus A. Milne-Edwards, 1879 (Crustacea, Isopoda, Cirolanidae) from Vietnam, with notes on the taxonomy of Bathynomus jamesi Kou, Chen & Li, 2017. ZooKeys 1223: 289-310, DOI: 10.3897/zookeys.1223.139335
E3178CAC9400549EA75F0DE102E892AF.taxon	description	Figs 4, 5, 6, 7, 8, 9 A – D, 10 A	en	Ng, Peter K. L., Sidabalok, Conni M., Nguyen, Thanh Son (2025): A new species of supergiant Bathynomus A. Milne-Edwards, 1879 (Crustacea, Isopoda, Cirolanidae) from Vietnam, with notes on the taxonomy of Bathynomus jamesi Kou, Chen & Li, 2017. ZooKeys 1223: 289-310, DOI: 10.3897/zookeys.1223.139335
E3178CAC9400549EA75F0DE102E892AF.taxon	diagnosis	Diagnosis. Clypeal region with lateral margin parallel, distal margin concave, apex narrowly acute, transversely rectangular (Figs 4 C, 5 C, 6 C, 9 A). Coxa of pereopod 7 narrows distally, curved posteriorly (Figs 5 D, 6 D, E, 9 B). Distinct row of setae present between pleotelson spines; 11 upwardly curved pleotelson spines; pleotelson 0.6 as long as wide (Figs 5 A, 9 D); pleotelson vaulted laterally (Figs 6 E, 9 C). Appendix masculina slightly shorter than or reaching to end of endopod of pleopod 2 (Fig. 10 A).	en	Ng, Peter K. L., Sidabalok, Conni M., Nguyen, Thanh Son (2025): A new species of supergiant Bathynomus A. Milne-Edwards, 1879 (Crustacea, Isopoda, Cirolanidae) from Vietnam, with notes on the taxonomy of Bathynomus jamesi Kou, Chen & Li, 2017. ZooKeys 1223: 289-310, DOI: 10.3897/zookeys.1223.139335
E3178CAC9400549EA75F0DE102E892AF.taxon	description	Description of male holotype. Body (Figs 4 A, B, 5 A, 6 A) 266 mm long, 135 mm wide at pereonite 5, length 1.9 times width, ovate in shape, coarsely punctate, without sculpture (Figs 4 A, 5 A, 6 A). Head ridge above eyes discontinuous (Figs 4 C, 5 B, 6 B). Clypeal region transversely rectangular, lateral margins parallel, distal margin slightly concave, apex narrowly subacute (Figs 4 C, 5 C, 6 B, C, 9 A). Antennula (Fig. 6 B); flagellum 1.2 longer than peduncle. Antenna peduncle article 4 - articulate (Fig. 6 B), article 4 about 1.4 times longer than article 3 (Fig. 6 B), flagellum extending to within pereonite 2 (Fig. 6 A, B). Mandible (Fig. 7 D) palp not reaching incisor, with setal fringe on lateral margin of distal half of article 2 and along article 3. Maxillula (Fig. 7 E) mesial lobe with 4 robust setae, lateral lobe with 9 keratinised robust setae. Maxilla (Fig. 7 C) lateral lobe with 9 keratinised robust setae, middle lobe with 7 keratinised robust setae, mesial lobe with fringe of long plumose setae. Maxilliped palp (Fig. 7 A) typical of genus; maxilliped endite with 4 coupling hooks (Fig. 7 B). Pereopod 1 (Fig. 8 A) ischium with 1 posteroproximal robust seta and 3 robust setae on posterodistal margin; merus with 6 robust setae on anterodistal angle, posterolateral margin with 4 robust setae in proximal row on and 3 robust setae in distal row; propodus 2.3 as long as wide, with 4 robust setae on posterior margin. Pereopod 2 (Fig. 8 B) ischium with 3 robust setae on posterior margin and 4 robust setae on posterodistal margin; merus with 9 robust setae on anterodistal angle, posteromedial margin with 3 robust setae in proximal row and 3 robust setae in distal row; propodus with 4 robust setae on posterior margin. Pereopod 7 (Fig. 8 C) basis 3.5 times as long as greatest width, inferior margin convex; ischium 0.5 times as long as basis, inferior margin with 1 robust seta, superior distal angle with 6 robust setae, inferior distal angle with 6 robust setae; merus 0.6 as long as ischium, as long as wide, inferior margin with 1 robust seta, superior distal angle with 11 robust setae, inferior distal angle with 13 robust setae; carpus as long as ischium, 2 times as long as wide, inferior margin with 3 robust setae (as 1 + 2), superior distal angle with 13 robust setae, inferior distal angle with 10 robust setae; propodus 0.9 as long as ischium, 3.8 times as long as wide, inferior margin with 2 clusters of robust setae (as 2 clusters of 2), superior distal angle with 8 robust setae, inferior distal angle with 1 robust seta; dactylus 0.5 as long as propodus. Coxa of pereopod 7 distally narrowed, gently curved posteriorly (Figs 5 D, 6 E, 9 B). Pleonite 3 (Fig. 6 E) not extending beyond pleonite 5. Pleonite 4 (Fig. 6 E) reaching to end pleonite 5. Penial process flat lobes (Fig. 4 B). Appendix masculina with parallel margins, not extending beyond endopod, distally narrowly rounded (appendix masculina absent on holotype male) (Fig. 10 A). Pleotelson (Figs 5 A, 6 F, 9 C, D) 0.6 time as long as greatest width, smooth (minute pores), with inconspicuous longitudinal carina on dorsal surface; dorsal surface distinctly convex (Figs 5 D, 6 E, 9 C, D); posterior margin with 11 long, prominent, upwardly curved spines and pair of small posterolateral spines, with setae between spines, central spine simple. Uropods (Figs 4 A, 6 F, 8 D, E) not extending beyond pleotelson. Peduncle with 3 short robust setae on caudolateral margin (Fig. 8 D); exopod and endopod with smooth lateral and distal margins; exopod lateral margin convex with 12 left and 11 right robust setae along margin, setal fringe continuous length (83.3 %), medial margin straight, distomedial corner rounded, distal margin convex with 5 left and 7 right robust setae, distolateral corner produced, acute; endopod lateral margin convex, distally straight, with 5 left and 6 right robust setae; medial margin posteriorly convex; distomedial corner rounded; distal margin straight with 12 left and 13 right robust setae; distolateral corner produced, acute. Female. Not known.	en	Ng, Peter K. L., Sidabalok, Conni M., Nguyen, Thanh Son (2025): A new species of supergiant Bathynomus A. Milne-Edwards, 1879 (Crustacea, Isopoda, Cirolanidae) from Vietnam, with notes on the taxonomy of Bathynomus jamesi Kou, Chen & Li, 2017. ZooKeys 1223: 289-310, DOI: 10.3897/zookeys.1223.139335
E3178CAC9400549EA75F0DE102E892AF.taxon	etymology	Etymology. The species named after the most famous Sith Lord in the Star Wars movie series, Darth Vader, whose helmet resembles the head of the new Bathynomus species.	en	Ng, Peter K. L., Sidabalok, Conni M., Nguyen, Thanh Son (2025): A new species of supergiant Bathynomus A. Milne-Edwards, 1879 (Crustacea, Isopoda, Cirolanidae) from Vietnam, with notes on the taxonomy of Bathynomus jamesi Kou, Chen & Li, 2017. ZooKeys 1223: 289-310, DOI: 10.3897/zookeys.1223.139335
E3178CAC9400549EA75F0DE102E892AF.taxon	distribution	Distribution. Known only from Vietnam. We are unable to determine the exact location where B. vaderi was trawled, as the dealers and fishermen would only say they were obtained from deep waters off Vietnam near the Spratly Islands.	en	Ng, Peter K. L., Sidabalok, Conni M., Nguyen, Thanh Son (2025): A new species of supergiant Bathynomus A. Milne-Edwards, 1879 (Crustacea, Isopoda, Cirolanidae) from Vietnam, with notes on the taxonomy of Bathynomus jamesi Kou, Chen & Li, 2017. ZooKeys 1223: 289-310, DOI: 10.3897/zookeys.1223.139335
