Saccogaster brayae, Nielsen, Jørgen G., Schwarzhans, Werner & Cohen, Daniel M., 2012

Nielsen, Jørgen G., Schwarzhans, Werner & Cohen, Daniel M., 2012, Revision of Hastatobythites and Saccogaster (Teleostei, Bythitidae) with three new species and a new genus, Zootaxa 3579, pp. 1-36 : 7-9

Saccogaster brayae n. sp.

Figs. 3 , 4 , 25 , Table 1 , 2, 4

Material examined (1 specimen, 36 mm, SL). Holotype: NMV A 29655-002, male, 36 mm SL, off northwestern Australia, Barrow L1 transect, 21°00’49’’S, 114°39’09’’E to 21°00’47’’S, 114°38’54’’E, R/V Southern Surveyor, Sherman sledge, 250–258 m, 10 June 2007.

Diagnosis. Saccogaster brayae differs from all other Saccogaster species in having a broken brown stripe between eye and hind margin of opercle (except for S. hawaii ), precaudal vertebrae 21 and total vertebrae 53, and becoming ripe at a very small SL (36 mm). Also the following combination of characters is diagnostic: A pair of free spines on frontal above and behind eyes, a large median sub-dermal ethmoidal spine in front of eyes with forward pointed tip; antero-ventrally directed spine at lower angle of preopercle; thin transparent skin; scales present on sides of body; three long gill rakers on anterior arch 4–5 times the length of gill filaments; palatines with 1–2 rows of teeth; pectoral peduncle longer than high; fin rays in dorsal 85, anal 52 and pectoral 18; otolith length to height = 1.9, otolith length to colliculum length = 3.1, sulcus without anterior projection.

Similarity. Saccogaster brayae seems most similar to S. hawaii by the brown stripe behind eye, the forward pointed tip of the ethmoidal spine and the scaled body. They differ by S. brayae having opercular spine ending in one prong (vs. three prongs), by long rakers on anterior arch 4–5 times length of filaments (vs. long rakers and filaments almost equal in length), precaudal vertebrae 21 (vs. 18), pectoral fin rays 18 (vs. 22) and dorsal fin rays 85 (vs. 92).

Description. The principal meristic and morphometric characters are shown in Table 4 . Head and body elongate and compressed with tapering caudal part and blunt snout. Most scales rubbed off but scale-pockets and a few remaining scales (0.8 mm long) indicate squamation on sides of body. Lateral line not visible. Dorsal fin origin above proximal part of pectoral fin and anal fin origin well behind midpoint of fish. Pectoral fin ending less than halfway to anus with peduncle a little longer than broad and free of body. Anterior gill arch with three spiny knobs on upper branch, a developed raker in angle and lower branch with two developed rakers with a knob in between followed by eight knobs. Developed rakers 4–5 times length of gill filaments ( Fig. 4 D). Two small pseudobranchial filaments. The well developed testes and intromittent organ ( Fig. 4 G) show that the specimen is a ripe male.

Axial skeleton (from radiographs): Number of precaudal vertebrae 21. Anterior neural spine very short. Neural spines 2–4 long, depressed and with pointed tips. Neural spines 5–20 short and with large basal parts, length of spines increasing posteriorad. Parapophyses developed on vertebrae 6–20. Pleural ribs distinct at vertebrae 1–8, but pleural ribs on remaining precaudal vertebrae and presence of epipleural ribs are questionable.

Dentition: Palatines with about 25 pointed teeth in 1–2 rows; larger teeth in inner row. Vomer boomerangshaped with about 25 pointed teeth in 2–3 irregular rows; six longer teeth in inner row. Premaxillaries with granular teeth except for five fangs at symphysis. Dentaries with 3–4 irregular tooth rows, outer rows with granular teeth and inner row with fangs.

Head morphology ( Fig. 4 A–C): Head profile concave above eyes. Head with pair of free spines as an integrated part of a transverse rim on frontal above and slightly behind eyes and a large, median sub-dermal ethmoidal spine in front of eyes with forward pointed tip. Anterior nostril placed close to upper lip and small posterior nostril placed close to eye. Head pores: 1 supraorbital pore at tip of snout, 2 anterior infraorbital pores below and in front of eye, 1 anterior mandibular pore at tip of jaw. Head skin thin, tight. No neuromasts visible.

Head with dusky background pigmentation, broken brown stripe between eye and hind margin of opercle and broken brown pigmentation patches below and behind eye. Upper jaw ends well behind eye with posterior margin vertically expanded. Opercular spine pointed, just reaching hind margin of operculum. Antero-ventrally directed spine at lower angle of preoperculum.

Otolith ( Fig. 4 E–F): Otolith oval, moderately thick; otolith length to height = 1.9, otolith height to thickness = 1.9. Dorsal and ventral rims gently curved, dorsal rim broadly undulating. Anterior and posterior tips regularly rounded resulting in a regular oval appearance of the otolith. Inner face flat with centrally positioned, undivided, small, oval, shallow sulcus without anterior projection. Otolith length to colliculum length = 3.1. Outer face convex.

Coloration: After five years of preservation body uniformly brownish with faint dark pigmentation dorsally. Head with dusky, dense pigmentation and a dark brown stripe from eye to hind margin of opercle. Larger, dark pigment spots on frontal plate seen through skin on dorsum. Eyes blue with yellow lens.

Biology and distribution ( Fig. 25 ). A viviparous species occurring on the upper continental slope. Known from a 36 mm male with well developed testes and intromittent organ, caught off northwestern Australia organ ( Fig. 4 G), caught at a depth of 250– 258 m.

Etymology. Named after Dianne Bray, MNV, for her support with material for this revision.

Figures

FIGURE 3. Saccogaster brayae, holotype, NMV A 29655 - 002, SL 36 mm (photo M. Krag).

FIGURE 4. Saccogaster brayae, holotype: A—Lateral view of head. B—Lateral radiograph of head. C—Dorsal view of head. D— Anterior right gill arch. E—Median view of right otolith. F—Dorsal view of right otolith. G—Intromittent organ.

FIGURE 25. Geographic distribution of Hastatobythites and Saccogaster in the Indo-West Pacific. Each marking may represent more than one locality.