Eustomias (Haploclonus) antea, Bárbara & Villarins & Luciano & Fischer & Artem & Prokofiev & Michael & Mincarone, 2024

Villarins, Bárbara T, Fischer, Luciano G, Prokofiev, Artem M & Mincarone, Michael M, 2023, Four new species of dragonfish genus Eustomias (Stomiiformes: Stomiidae: Melanostomiinae) from the western tropical Atlantic, with remarks on Eustomias minimus Clarke, 1999, Zoological Journal of the Linnean Society 202 (1), pp. 1-17 : 3-4

publication ID	https://doi.org/ 10.1093/zoolinnean/zlad163
publication LSID	lsid:zoobank.org:pub:D261FD0-638C-46AB-AD43-B6941119E9F5Corresponding
DOI	https://doi.org/10.5281/zenodo.14552566
persistent identifier	https://treatment.plazi.org/id/03AE87AA-FFA0-FFD0-FF5D-F942DD0DFEAA
treatment provided by	Plazi
scientific name	Eustomias (Haploclonus) antea
status	sp. nov.

Treatment

Eustomias (Haploclonus) antea sp.nov.

( Figs 2 View Figure 2 , 7A View Figure 7 , 9 View Figure 9 ; Tables 1 View Table 1 and 2 View Table 2 )

Zoobank registration: urn:lsid:zoobank.org:act: 9DC84F59- 4B38-46E5-9375-4A7CDC577183

Eustomias sp . – Villarins et al. 2022: 60 [potential new species; off northeastern Brazil].

Eustomias sp . 2. – Eduardo et al. 2022: 6 [potential new species; off northeastern Brazil].

Holotype: NPM 4880, 124 mm SL, Brazil, off Fernando de Noronha Archipelago , ABRACOS, station AB2#41A, 03°19 ʹ 59″S, 32°24 ʹ 42″W to 03°19 ʹ 32″S, 32°25 ʹ 05″W, 0–430 m, RV Antea, mid-water trawl, coll. Leandro Eduardo, Paulo Travassos, and crew, 26 April 2017, 21:44–22:06 h. GoogleMaps

Diagnosis: A species of Haploclonus with: long chin barbel (45.2% SL) lacking appendages, ending in a very small terminal bulb (0.3% SL; 2.6% HL) with a pigment spot at tip, and without terminal filaments ( Figs 2 View Figure 2 , 7A View Figure 7 ); 61 vertebrae.

Description: Chin barbel long, without appendages, almost reaching the base of pelvic fins (45.2% SL, 361.3% HL) (Fig. 2A). Stem unpigmented with small circular black spots associated with photophores, axis sparsely pigmented internally. Chin barbel ending in a very small and elongated terminal bulb (0.3% SL, 2.6% HL), the same width as the stem, with a small pigment spot at its tip and without terminal filaments ( Figs 2C View Figure 2 , 7A View Figure 7 ).

Dorsal-fin rays 26, anal-fin rays 34, pectoral-fin rays three, pelvic-fin rays seven, branchiostegal rays 13, and total vertebrae 61. Linear photophores in the series: BR 10, IP 7, PV 28, VAV 14 (last five above anal-fin base), OV 27, VAL 15 (last four above anal-fin base), AC 18, IA 49, IC 67, OA 42, and OC 60 (Table 1). Orbital light organs small, subequal in size; SO length 0.2% SL (1.9% HL) and PO length 0.3% SL (2.6% HL), directed diagonally. Small photophores on head and body randomly located. A pair of luminous spots near nostrils and a few aggregations of luminous spots near PV photophores. No ventral groove.

Eight teeth on premaxilla, with first, third, and sixth fixed (Fig. 2B); second tooth the longest (1.8% SL, 14.2% HL). Five teeth on dentary, with first, third and fifth fixed (Fig. 2B); second tooth the longest (1.1% SL, 9.0% HL). Twenty-two teeth on maxilla, comb-like and directed backwards. Maximum length of the gill filaments at first arch 1. 5 mm (0.8% SL, 6.4% HL).

Measurements (as a percentage of SL): body depth (behind head) 6.8, body width (at pelvic insertions) 5.0, dorsal-fin base length 15.3, anal-fin base length 23.4, predorsal length 79.0, preanal length 71.8, prepelvic length 58.9, pelvic–anal distance 14.9, pelvic fin length 16.1, snout to anus 74.2, caudal peduncle length 2.6, caudal peduncle depth 1.9, head length 12.5, snout length 4.3, eye diameter 2.4, interorbital space 2.9, and upper jaw length 10.9. Measurements (as a percentage of HL): snout length 34.2, eye diameter 20.0, interorbital space 23.2, and upper jaw length 80.6; PO /Eye 0.13 and SO /Eye 0.10 (Table 2).

Colour in alcohol: body brown; fin rays lightly pigmented near base. Six dorsal paired spots between occiput and dorsal-fin origin.

Distribution and habitat: Known only from the type locality, off northern Fernando de Noronha Archipelago, Brazil (Fig. 9). The holotype was collected at 430 m depth, where the temperature was 8.5°C, salinity 34.7, and dissolved oxygen 3.6 mL/L. The predominant water mass at this depth is the South Atlantic Central Water (SACW) ( Stramma and England 1999).

Etymology: The specific name honours the Antea, the Research Vessel of the French oceanographic fleet, which conducts many deep-sea exploratory surveys around the world, including the ABRACOS expedition off northeastern Brazil.

Comparison: Eustomias antea shares the main diagnostic features with those in the subgenus Haploclonus , such as three pectoral-fin rays, seven pelvic-fin rays, slender barbel with no external pigment and with photophores on stem, six dorsal paired spots, and no deep ventral groove, but lacks appendages on barbel stem and possesses a high vertebral count (61). Within the subgenus Haploclonus , most species have the usual range of vertebrae, 56–59, except E. treoavasae with a higher count (59–63) ( Gibbs et al. 1983). However, E. antea can be distinguished easily from E. treoavasae by the presence of circular black spots on the stem (vs. absence) associated with photophores and one small terminal bulb on the barbel (vs. presence of four or five bulbs on the barbel) ( Gibbs and Craddock 1973, Parin and Pokhil’skaya 1974). Within the subgenus Haploclonus , only Eustomias simplex Regan & Trewavas, 1930 and Eustomias lucenae are characterized by a simple barbel morphology (Regan and Trewavas 1930, Morrow and Gibbs 1964; present study). However, E. antea still differs from these congeners by three characters: (i) barbel length [45.2% SL vs. 47.3–68.6% (usually> 50%) SL in E. simplex and 9.6% SL in E. lucenae ]; (ii) presence of a minute, almost imperceptible terminal bulb with 0.3% SL and 2.6% HL (vs. a prominent terminal bulb, 2–4 times as long as wide, often slightly constricted at mid-length or in proximal half, 1.8–4.1% SL and 12.5–33.3% HL in E. simplex , and prominent and asymmetric terminal bulb with 0.8% SL and 6.9% HL in E. lucenae ); and (iii) presence of a pigment spot at the tip of the bulb (vs. absent in both E. simplex and E. lucenae ) (Regan and Trewavas 1930, Morrow and Gibbs 1964; present study). Although this new species shares some features with the three-pectoral-rayed subgenus Nominostomias (barbel stem with a little or no external pigment, without appendages; no branches proximal to terminal bulbs; no ventral groove posterior to pectoral-fin base), it differs from it mainly by the presence of black spots associated with photophores on the barbel stem, no terminal filaments, lower vertebral count 61 (vs. 64–71, mostly 67–69), and lower serial photophores counts, IC 67 (vs. 69–80, mostly 75–78), and OC 60 (vs. 63–77, mostly 69–72) ( Gibbs et al. 1983).