Rhynchactis sp.

Mincarone, Michael Maia, Afonso, Gabriel Vinícius Felix, Di Dario, Fabio, Eduardo, Leandro Nolé, Frédou, Thierry, Lucena-Frédou, Flávia, Bertrand, Arnaud & Pietsch, Theodore Wells, 2021, Deep-sea anglerfishes (Lophiiformes: Ceratioidei) from off northeastern Brazil, with remarks on the ceratioids reported from the Brazilian Exclusive Economic Zone, Neotropical Ichthyology 19 (2), pp. 1-28 : 21-22

Rhynchactis sp.

( Figs. 5 , 6B )

Geographical distribution. Two specimens were collected off Rio Grande do Norte State and Fernando de Noronha Archipelago between depths of 650 and 800 m ( Fig. 5 ). As discussed below, they could not be identified to species, but represent the first record of the genus in Brazilian waters.

Remarks. Of the three valid species of Rhynchactis , two occur in the Atlantic: Rhynchactis leptonema Regan, 1925 and Rhynchactis macrothrix Bertelsen & Pietsch, 1998 (Pietsch, 2009). Both species are poorly represented in collections and their geographic distributions are poorly known (Pietsch, 2009). Rhynchactis leptonema has been collected in a few localities of the Atlantic and Pacific (off Hawaii and Taiwan). In the Atlantic, it is known from the holotype collected in the western Tropical Atlantic ( ZMUC P92133, 8º19’N 44º35’W). Rhynchactis macrothrix is also known from widely spread localities in the Atlantic and the western Indian and western Pacific Oceans. In the Atlantic, it is known from three specimens: the holotype collected in central equatorial waters ( ISH 605/74, 7º55’N 32º41’W), and two specimens collected off Bermuda and in the Gulf of Mexico (Bertelsen, Pietsch, 1998; Pietsch, 2009).

The larger specimen reported here ( NPM 4425, 113 mm SL; Fig. 6B ) is in overall good condition but while it retains the full length of the illicium, the skin of the structure has been lost. The illicium length (208% SL) clearly indicates that it is not R. leptonema (maximum 177% SL; Bertelsen et al., 1981), being more similar in that respect to R. microthrix (210% SL; Bertelsen, Pietsch, 1998). The smaller specimen ( NPM 5014) is an unidentified juvenile.

Material examined. NPM 4425 , 1, 113 mm ( Fig. 6B ) , RV Antea, sta. AB2/42A, 3°15’28.1”S 31°48’29.1”W to 3°15’27.8”S 31°50’40.6”W, 780 m, 27 Apr 2017, 12:23– 12:26 h; NPM 5014 , 1 , 42 mm , RV Antea, sta. AB2/39, 4°52’26.9”S 34°35’22.9”W to 4°50’52.8”S 34°51’04.7”W, 650–800 m, 24 Apr 2017, 21:49–22:37 h.

Figures

FIGURE 5 | Records of the Caulophrynidae, Gigantactinidae, and Linophrynidae in Brazilian waters: Caulophryne sp. (pentagon), Gigantactis longicirra (square), Gigantactis vanhoeffeni (cross), Gigantactis watermani (triangle), Gigantactis sp. (diamond), Rhynchactis sp. (star), Linophryne arborifera (circle). Full symbols represent specimens collected during the ABRACOS surveys and open symbols are records from the literature (see text). Selected Brazilian States and oceanic islands are RN – Rio Grande do Norte, BA – Bahia, ES – Espírito Santo, RJ – Rio de Janeiro; SPA – Saint Peter and Saint Paul Archipelago, FN – Fernando de Noronha Archipelago, RA – Rocas Atoll. Dashed line represents the outer limit of the Brazilian Exclusive Economic Zone.

FIGURE 6 | Species of the Gigantactinidae reported in this study: A. Gigantactis watermani, NPM 4424, 170 mm SL; B. Rhynchactis sp., NPM 4425, 113 mm SL. Scale bars = 10 mm.