Taractes rubescens

Carvalho-Filho, Alfredo, Marcovaldi, Guy, Sampaio, Cláudio L. S., Paiva, Isabel G. & Duarte, Luiz A. G., 2009, First report of rare pomfrets (Teleostei: Bramidae) from Brazilian waters, with a key to Western Atlantic species, Zootaxa 2290, pp. 1-26 : 14-16

Taractes rubescens

Keeltail Pomfret, Lira. ( FIG. 9 )

Diagnostic characters: Based on examined specimen (in brackets) and literature data ( Mead, 1972; Thompson & Russell, 1996; Thompson, 2003, 2008; McEachran & Fechhelm, 2005; Haedrich, 1986; Santos et al., 1997).

Body compressed, rather fusiform compared to that of most Bramidae , the greatest depth 36–45% (37%) of standard length; dorsal profile of head almost straight, the forehead slightly concave; snout pointed; precaudal grooves well developed; strong, rather high and well developed lateral keel on the caudal peduncle, a character that distinguish this species from all other known species of the family; dorsal fin rays 30–32 (31); anal fin rays 19–23 (19); pectoral fin extends to anterior anal fin rays, with 19–22 (19) rays; horizontal series of scales 41–48 (48), to origin of peduncle’s keel; gill rakers, 1–3 + 7–8 (2 + 7), not counting rudiments; gill filaments more than three times length of rakers; scales on sides of body cycloid and smooth, spines present only in young; posterior profile of upper lobe of the caudal fin falcate, the lower somewhat protruding medially. Color varies from almost black to dark brown with bronze to silver sheen, belly somewhat lighter; all fins with the same dark color of the body and a silvery sheen; caudal fin dark with a posterior white margin less discernible on upper lobe. The specimen examined had the outer border of the caudal fin’s lower lobe shaped like an “S”; this same “S” shape also present in the other species of the genus, T. asper ( FIG 22 ), thus leading us to conclude that this is a character of the genus not yet described. Also noteworthy, the main character of T. rubescens , the lateral keel on the caudal peduncle, is not reported by Thompson and Russell (1996) after examining 43 specimens.

2. Crustacea, Decapoda , Oplopheridae.

Habitat, Depth and Presumed Solitary Habit: The keeltail pomfret is an offshore pelagic species occurring from the surface to about 600 m depth, apparently solitary, more often captured at night ( Thompson & Russell, 1996; Thompson, 2008; present paper). There are no records about its temperature preferences.

Diet: The examined specimen’s stomach contained two rather large Aristeidae pelagic shrimps, one of them in FIG. 10 .

Distribution: Central Pacific: Hawaii. Eastern Pacific: Costa Rica to Peru. Eastern Atlantic: off West Africa, Azores and Madeira Islands. Western Atlantic: Gulf of Mexico, Trinidad and Bahia in Brazil. The present paper extends the known occurrence of the keeltail pomfret southwards for about 3,500 kilometers.

Proposed Brazilian name: “Lira” (= lyre) after the tail shape, and used by Bahia’s artisan fishermen that caught this fish.

Finally, shortly before the submission of this work a third uncommon bramid was captured at the very same site off Bahia: an adult male of the bigscale pomfret, Taractichthys longipinnis , hooked in about 200 meters, 1,300 meters from the bottom, also preserved in the PROJETO TAMAR collection. To our knowledge this is the first report of an adult of this species in Southwestern Atlantic waters. It differs from its only congener, Taractichthys steindachneri (Döderlein, 1883) , from the Indian and Pacific Oceans, by the higher number of scales in horizontal series (more than 38, usually 42–45 against 38 or fewer in T. steindachneri ), as well as by minor morphometric meristic features ( Mead, 1972; Haedrich, 1986; Smith, 1986; Thompson & Russell, 1996).

Figures

FIGURE 10. Stomach content of Taractes rubescens: Crustacea, Decapoda, Aristeidae caught off Bahia, Northeast Brazil.

FIGURE 22. Taractes asper, about 45 cm SL, recently collected from Hawaii. Photograph by NMFS Pacific Islands Region Observer Program, Honolulu, Hawaii.

FIGURE 9. 1. Taractes rubescens, male, 487 mm SL, caught at 600 m depth off Praia do Forte, caught off Bahia, Northeast Brazil: 2 and 4. Caudal peduncle’s keel. 3. Dorsal fin.