Wednesday, May 29, 2024

[Ichthyology • 2024] Eustomias robertsi • A New Species of Eustomias (Nominostomias) (Stomiiformes: Stomiidae) from the Kermadec Ridge—Tonga Trench Region, western South Pacific Ocean, with Notes on the barbel morphology of E. trewavasae


Eustomias robertsi 
Stewart, Kenaley & Sutton, 2024
 
 
Abstract
A new species of dragonfish Eustomias (Nominostomiasrobertsi is described from the western South Pacific Ocean. The new species, the first record of a member of Eustomias (Nominostomias) Group III (sensu Gibbs et al. 1983) from the region, it is most similar to Eustomias suluensis in barbel morphology. However, it has a smaller proximal and distal bulb distance, the smallest distal inter–bulb value in the group, and much longer terminal filaments.
Comments are also provided on the morphology of the diagnostic features on the barbel of Eustomias trewavasae, including an important character overlooked in the original description of the species. The barbel morphology is redescribed taking this into account.
A brief observation is made recording the first record of the subgenus Triclonostomias from the western South Pacific Ocean.

Key words: Taxonomy, marine fish, deep-sea, identification, dragonfish

Eustomias robertsi n. sp. holotype, NMNZ P.013765.; 232.1 mm SL. Illustration: Michelle Freeborn.

Teeth of Eustomias robertsi n. sp. holotype, NMNZ P.013765. Fixed teeth (black), remaining teeth depressible. Illustration by Michelle Freeborn.
Freshly caught paratype of Eustomias robertsi n. sp. NMNZ P. 058340; 144.6 mm SL. Photo Carl Struthers/Thom Linley.

Eustomias (Nominostomiasrobertsi sp. nov.

Diagnosis: The new species is diagnosed from others in Eustomias (Nominostomias) Group III by the combination of the barbel morphology of: A very small distance between proximal and distal bulbs (0.1–0.2 % SL; 0.01–0.07 times distal bulb length), and three long terminal filaments, longest 30.4–42% SL.


Andrew L. Stewart, Christopher P. Kenaley and Tracy Sutton. 2024. A New Species of Eustomias (Nominostomias) (Stomiiformes: Stomiidae) from the Kermadec Ridge—Tonga Trench Region, western South Pacific Ocean, with Notes on the barbel morphology of E. trewavasae.  Zootaxa. 5458(1); 93-107. DOI: 10.11646/zootaxa.5458.1.5