Grammatostomias ovatus Prokofiev, 2014

Villarins, Bárbara T., Dario, Fabio Di, Eduardo, Leandro N., Lucena-Frédou, Flávia, Bertrand, Arnaud, Prokofiev, Artem M. & Mincarone, Michael M., 2022, Deep-sea dragonfishes (Teleostei: Stomiiformes) collected from off northeastern Brazil, with a review of the species reported from the Brazilian Exclusive Economic Zone, Neotropical Ichthyology (e 220004) 20 (2), pp. 1-78 : 53-54

Grammatostomias ovatus Prokofiev, 2014

( Fig. 16B )

Diagnosis. Grammatostomias ovatus differs from congeners by the luminous tissue on flank always longer than deep, forming an elongate circle with a wavy outline, ending far in advance of the pelvic-fin origin; 6–9 pectoral-fin rays; first pectoral-fin ray isolated and heavily pigmented, remaining rays unpigmented, with masses of luminescent tissue, enormously developed on the second ray; PV 17–18 (Prokofiev, 2014; Prokofiev, unpubl. data).

Geographical distribution. The species was recently described based only on the holotype from the Canary Basin (Prokofiev, 2014), but additional specimens are also known from the tropical Atlantic Ocean, between 20ºN and 4ºN (Prokofiev, unpub. data). Grammatostomias ovatus is therefore reported for the first time in the South Atlantic based on one specimen collected off Pernambuco State in the Brazilian EEZ, between depths of 45 and 200 m ( Fig. 14D ) .

Remarks. Menezes et al. (2003) included a morphologically similar species, G. circularis Morrow, 1959 , in a checklist of Brazilian marine fishes based on Morrow, Gibbs (1964), who actually did not record the species in the Brazilian EEZ. Melo et al. (2020: 208), in turn, considered the occurrence of G. circularis as not confirmed in Brazilian waters. In the description of G. ovatus, Prokofiev (2014) indicated that the species could be distinguished from G. circularis by the number of pectoral-fin rays (6 vs. 9). Examination of additional specimens of G. ovatus indicates that the number of pectoral-fin rays is variable in the species (6–9). However, G. circularis is still distinct from G. ovatus in the shape of the luminous loop on the flank, which is nearly circular in the former (e.g., Morrow, Gibbs, 1964). The degree of elongation of the luminous loop in G. ovatus is also somewhat variable, but it is always longer than deep in that species instead of almost as long as deep in the case of G. circularis . The luminous tissue associated with the pectoral-fin rays of G. ovatus is also conspicuously more developed than in G. circularis , even though some ontogenetic variation in this character might be expected. In summary, the additional specimens of G. ovatus examined after its description in 2014 supports the distinction between that species and G. circularis ; the occurrence of the later in Brazilian waters has not yet been confirmed.

Specimen examined. 1: NPM 3191, 1 (67 mm), AB1#51.

Figures

FIGURE 14 | Records of species of the Melanostomiinae (A–F) collected during the ABRACOS expeditions off northeastern Brazil. Oceanic islands: RA, Rocas Atoll; FN, Fernando de Noronha Archipelago.

FIGURE 16 | A. Grammatostomias dentatus, NPM 3184, 114 mm SL; B. Grammatostomias ovatus, NPM 3191, 67 mm SL; C. Leptostomias gladiator, NPM 4782, 83 mm SL. Scale bars = 10 mm.