Trachipteridae Swainson 1839

Family Trachipteridae Swainson 1839 Ribbonfishes, Dealfishes

Diagnosis (adults). Body elongate (to 2 m SL), ribbon-like, and laterally compressed (strongest compression in Trachipterus, least in Zu). Body depth decreasing gradually, tapering to a narrow caudal peduncle. Upper jaw highly protrusible, maxilla broad. Both jaws with recurved pointed teeth. Vomer with 1–2 median teeth. Nostrils single (2 nostrils in juvenile Desmodema). Anal fin absent. Dorsal fin originates above or slightly posterior to the eye. Dorsal fin long, extending entire body length to tail. Dorsal-fin rays 120–197, first 5–6 rays reduced in length during ontogeny, and only represented by fin bases in adults (elongate and flexible in juveniles); lateral spinules present along length of the fin rays (most obvious in juveniles). Caudal fin with either 1 (Desmodema) or 2 (Trachipterus and Zu) lobes; total caudal-fin rays usually 6 to 17; ventral rays of caudal fin either reduced (elongate in juvenile Trachipterus and Zu) or absent (in Desmodema); dorsal rays of caudal fin fan-like and sometimes turned dorsally (Trachipterus and Zu); caudal-fin rays with minute, laterally projecting spinules, weak or absent on central rays. Pectoral fin with 1 + 10-14 rays; the first fin ray extremely short. Pelvic fin with 5 to 11 rays (elongate and fanlike in juveniles), either reduced to bases or lost entirely (as in Desmodema); pelvic-fin rays with minute, laterally projecting spinules, weakly developed or absent on posterior-most pelvic rays. Skin covered with bony, bump-like tubercles and pierced with numerous pores. Thin cycloid scales present in all genera. Lateral-line scales with 1 (occasionally 2) spines. Ribs absent, swim bladder rudimentary or absent. Posterior caudal vertebral centra elongate, 2 to 4 times longer than the tenth vertebrae.

Color. Body silver to dark black or brown; frontal profile from dentary symphysis to dorsal-fin origin black. Bright red or crimson dorsal fins in life, black once preserved.

Remarks. Although there are more than thirty nominal species of Trachipteridae (Table 1), there are likely fewer than 10 valid species, with significant taxonomic uncertainty remaining in Trachipterus. Despite the abundance of alpha-taxonomic issues, three genera are readily recognized: Trachipterus, Desmodema, and Zu. Previous generic keys have incorporated characters here found to be incorrect or are the result of an amalgamation of numerous life history stages (for examples, see Walters & Fitch 1960; Palmer 1961; Fitch 1964; Scott 1983; Heemstra & Kannemeyer 1984; and Hayashi 2002). The following key can be used for identification of both juvenile and adult stages, and incomplete specimens.