Parasaccogaster rhamphidognatha

biology_ecology

Biology and distribution (Fig. 26). Parasaccogaster rhamphidognatha is only known from the holotype caught at a depth of 210 m in the Gulf of Mexico.

Revision of Hastatobythites and Saccogaster (Teleostei, Bythitidae) with three new species and a new genus

description

Description. The principal meristic and morphometric characters are shown in Table 7. Head and body elongate and compressed with blunt snout and tapering tail. Scales absent. Lateral line obsolete. Dorsal fin origin above gill slit, anal fin origin well behind midpoint of fish and pectoral fins very short ending 1 / 5 to origin of anal fin. Anterior gill arch with 2 – 3 flat, spiny plates on upper branch, a short, slightly prolonged raker in angle and lower branch with 1 – 2 similar sized rakers followed by six spiny plates. Gill filaments short. Two pseudobranchial filaments. The intromittent organ is provided with a 6 mm long penis indicating a ripe male. Axial skeleton (from radiographs): Number of precaudal vertebrae 20. Anterior neural spine one third the length of second spine. Neural spines gradually decreasing in length. Neural spines 6 – 8 with slightly blunt tips. Tips of all other neural and haemal spines pointed. Parapophyses on vertebrae 4 – 20. Ribs obsolete. Dentition: Palatines with small, pointed teeth in a single row. Vomer boomerang-shaped with band of small, pointed teeth. Premaxillaries and vomer with an outer, narrow band of granular teeth and an inner row wit

Revision of Hastatobythites and Saccogaster (Teleostei, Bythitidae) with three new species and a new genus

diagnosis

Diagnosis. Parasaccogaster rhamphidognatha differs from the other two species of the genus by the antrorse, hook-like projection at the postero-ventral angle of the maxillary, a median spine on frontals above and behind eyes and the low number of pectoral fin rays (12). Also the following combination of characters is diagnostic: A strong, ethmoidal spine; pectoral peduncle prolonged and adnate to body; 2 – 3 slightly developed rakers on anterior gill arch; palatines with a single tooth row; gill filaments on anterior arch short, 1 – 2 times length of developed rakers; precaudal vertebrae 20 and total vertebrae 58; fin rays in dorsal 77, anal 49 and pectoral 12. Similarity. Parasaccogaster rhamphidognatha is most similar to P. n o r m a e with hidden opercular spine, nasal chamber not sooty black and distinctly more anal fin rays and vertebrae than found in P. melanomycter. P. rhamphidognatha differs from P. normae by the shorter gill filaments on anterior arch (1 – 2 times length of long rakers vs. 4 – 5 times), fewer pectoral fin rays (12 vs. 17 – 19), presence of ethmoidal spine (vs. spine absent) and a single median spine on frontal (vs. pair of small spines).

Revision of Hastatobythites and Saccogaster (Teleostei, Bythitidae) with three new species and a new genus

materials_examined

Material examined (1 specimen, 60 mm SL). Holotype: LACM 44189 - 1, male, 60 mm SL, Gulf of Mexico, Mississippi delta, 29 ° 13.5 ’ N, 88 ° 16.5 ’ W, R / V Alaminos, st. 69 A 13 - 43, 210 m, 4 – 16 Oct. 1969.

Revision of Hastatobythites and Saccogaster (Teleostei, Bythitidae) with three new species and a new genus