Eustomias shunyo, a new species of barbeled dragonfish (Stomiiformes, Stomiidae) from the western North Pacific

• Published in: Ichthyological research 2024-01, Vol.71 (1), p.48-55
• Main Authors: Kimura, Katsuya, Tsuda, Yuichi, Nakayama, Naohide
• Format: Article
• Language: English
• Subjects: Animal morphology; Animal Systematics/Taxonomy/Biogeography; Biomedical and Life Sciences; Chromatophores; Colour; Congeners; Ecology; Eustomias; Filaments; Fins; Freshwater & Marine Ecology; Identification keys; Life Sciences; Meristic counts; New species; Photophores; Pigmentation; Vertebrae; Zoology
• ISSN: 1341-8998; 1616-3915
• DOI: 10.1007/s10228-023-00911-7

A new barbeled dragonfish, Eustomias shunyo sp. nov., is described based on three specimens [219.1–256.4 mm in standard length (SL)] collected at depths of 30–180 m from the Shatsky Rise in the western North Pacific. The new species is included in the subgenus Urostomias Regan and Trewavas 1930 and distinguishable from all congeners by the following combination of characters: 30 dorsal-fin rays; 48–49 anal-fin rays; 9–10 pectoral-fin rays; 7 pelvic-fin rays; 29–31 PV (photophores in ventral series between pectoral- and pelvic-fin insertions); 26–27 AC (photophores from dorsal to anal fin to end of row); 69–72 vertebrae; preanal length 63.7–65.3% SL; head length 9.7–10.1% SL; barbel length 12.2–13.7% SL; single luminous gland on upper margin of caudal fin; stem of barbel lacking external pigmentation except for its proximal portion, and melanophores sparsely scattered around small photophores on ventral side of stem; pale yellow patches arranged in 1 or 2 rows on dorsal and ventral sides of barbel stem; single or pared filaments on dorsal side of distal portion of barbel stem just before terminal bulb; single leaf-shaped dark patch on ventral side of barbel bulb. The revised diagnosis and a key to species of the subgenus Urostomias are presented.