Oneirodes formosanus, Ho & Shao, 2019

Ho, Hsuan-Ching & Shao, Kwang-Tsao, 2019, Two new deep-sea anglerfishes (Oneirodidae and Gigantactidae) from Taiwan with synopsis of Taiwanese ceratioids, Zootaxa 4702 (1), pp. 10-18 : 10-18

Oneirodes formosanus sp. nov.

Formosa dreamer

Figs. 1 A–B, 2A–B

Holotype. ASIZP 59950 , adult female, 92.6 mm SL, off Daxi , Yilan, NE Taiwan, ca. 24°53.63’ N, 122°03.49’E, ca. 400–600 m, bottom trawl, 20 Mar. 1998, from bycatch.

Diagnosis. A species of Oneirodes with metamorphosed female differing from congeners in having an elongated terminal papilla on esca; a deep caudal peduncle (15.4% SL); a single simple, elongate, unbranched anterior escal appendages, with internal pigmentation; no medial and lateral escal appendages; a simple, elongate, posterior escal appendage, tapering distally, without internal pigmentation; terminal escal papilla elongated and cylindrical, internally pigmented, without distal pigment spots ( Fig. 2 ).

Description. Dorsal-fin rays 6; pectoral-fin rays 16; anal-fin rays 4; caudal-fin rays 9. Premaxillary teeth 23; dentary teeth 22; vomerine teeth 4. Measurements in % SL: illicial length 25.5; head length 35.1; head depth 39.7; premaxillary length 28.9; lower jaw length 42.4; caudal-peduncle depth 15.4.

Escal appendage pattern B ( Pietsch, 1974 a: 34, fig. 60B): anterior escal appendage cylindrical, elongated, tapering, unbranched, about twice escal height, with internal pigmentation; medial and lateral escal appendages absent; posterior escal appendage slender, about four times escal height, without internal pigment; escal pore relatively large, lying between terminal escal papillae and base of posterior escal appendage; terminal papilla elongated, cylindrical, with internal pigmentation, as long as the esca ( Fig. 2A ).

Opercle bifurcate, upper fork narrow, pointed distally, lower fork slender and slightly curved; length of lower fork of opercle 26.3% SL; ratio of lengths of upper and lower forks of opercle 0.5; subopercle relatively long and narrow, without indentation on posterodorsal margin, upper part tapering to a point, lower part broad and rounded ( Fig. 2B ). Pharyngobranchials II and III with well-developed teeth; epibranchial teeth absent.

Distribution. The Oneirodes formosanus is known only from the holotype collected from northeastern Taiwan off Daxi at depth ca. 400– 500 m.

Etymology. Named for the type locality, Formosa, an old name of Taiwan meaning the beautiful island.

Remarks. The relatively simple escal structure, deep caudal peduncle, and elongate terminal papilla can separate Oneirodes formosanus sp. nov. from congeners sharing the same escal pattern B. Of the congeners, it is most similar to O. eschrichtii Lütken, 1871 and O. bulbosus Chapman, 1939 , but can be distinguished by lacking median and anterolateral appendages and having an unbranched anterior appendage. It is more or less similar to O. thompsoni ( Schultz, 1934) , O. flagellifer ( Regan & Trewavas, 1932) and O. bradburyae Grey, 1957 , but can be distinguished by lacking filaments on the anterior appendage and having an elongated terminal papilla and slender and unbranched subopercle.

Figures

FIGURE 1. Drawing of Oneirodes formosanus sp. nov., ASIZP 59950, holotype, 92.6 mm SL. A. Preserved specimen. B. Drawing of holotype.

FIGURE 2. Esca (left) and operculum (right) of Oneirodes formosanus sp. nov., from the holotype. A, anterior appendage; P, posterior appendage; TP, terminal papilla; O, opercle; SO, subopercle. Scale bar is 1 mm.