Benthocometes australiensis, Nielsen, Jørgen G., 2010

Nielsen, Jørgen G., 2010, Revision of the bathyal fish genus Benthocometes (Teleostei: Ophidiidae) with a new species from off NW Australia, Zootaxa 2561, pp. 59-68 : 60-64

Benthocometes australiensis n. sp.

Figs. 1–4

Material examined. Holotype: NMV A 29728 -016, female, 93 mm SL, off northwestern Australia, Kulumburu L29 transect, 13°15’54’’S, 123°22’27’’E to 13°16’21’’S, 123°21’24’’E, R/V Southern Surveyor, beam trawl, 390–394 m, 12 Apr. 2008.

Comparative material. See examined specimens of B. robustus (p. 6)

Diagnosis. Benthocometes australiensis differs from the only other species in the genus, B. robustus , by the low number of long gill rakers on anterior arch (3 vs 9–12); few predorsal pterygiophores (4 vs 7–10); form of palatine dentition (circular vs elongate); predorsal length (22.0 vs 26.5–31.0 % SL); upper jaw length (8.7 vs 11.0–13.0 % SL); dorsal fin origin above vertebra no. 3 (vs 6–7); anal fin origin below dorsal fin ray no. 24 (vs 17–20); few, fang-like teeth (vs many, small, granular teeth); distinct supraorbital pores (vs pores undeveloped).

Description. The major meristic and morphometric characters are shown in Table 1 . Body short and robust and head small with blunt snout. Both head and body fully covered by small (1.3 mm under pectoral fin), oval, overlapping scales. Lateral line running midway between dorsal edge and midline of fish ending about one head-length from base of caudal fin. Vertical fins joined. Origin of dorsal fin far forward above base of pectoral fin, anal fin origin anterior to midpoint of fish, pectoral fin placed below midline of body almost reaching anus, pelvic fins reaching halfway to anal fin. Anterior nostril a low tube with a skin flap, posterior a mere hole. Tip of snout with about 10 small, black skin flaps. Diameter of eye larger than length of snout. Short upper jaw ending below anterior margin of eye. Opercle with two, sharp spines, upper pointing backwards and lower postero-ventrally; none of them reaching hind margin of opercle. Anterior gill arch ( Fig. 2 A) with 2–3 small, spiny knobs on upper branch and lower branch with three long rakers and 6–7 small, spiny knobs. Longest of the ca. 50 gill filaments longer than rakers. Pseudobranchial filaments (6–8) very small.

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* Cf. Fig. 6 ; ** Mean value in parentheses.

Head pore system: Number of pores in supraorbital row three, in infraorbital row five, in mandibular row three and in preopercular row two.

Dentition ( Fig. 3 A): All teeth small, but fang-like; anteriorly in each premaxillary a more distinct fang. Premaxillaries with ca. 15 teeth, uniserial posteriorly. Vomerine tooth patch round with ca. 15 teeth. Palatine dentition an oval patch with 10–12 teeth. Dentaries with 15–20 teeth, uniserial posterorly. One elongate, median basibranchial tooth patch.

Sagittal otolith ( Fig. 4 A–C): Otolith with blunt anterior and pointed posterior end, ventral rim even and dorsal rim with angle anteriorly; height 70 % of otolith-length; thickness 25 % of length; sulcus 65 % of otolith-length with caudal part almost as long as osteal part.

Axial skeleton (based on radiographs): Number of precaudal vertebrae 12. Anterior neural spine half length of second spine. Precaudal vertebrae 1–6 with pointed neural spines, 7–12 with blunt spines and all caudal neural spines with pointed tips. Anterior five haemal spines with blunt tips and the rest with pointed tips. Neural spines on precaudal vertebrae 5–12 with enlarged bases. Parapophyses on vertebrae 7–12 increasing in lengths posteriorad. Pleural ribs on vertebrae 3–12. Epipleural ribs not observed.

Coloration. Ground color of preserved specimen brownish with numerous small, black spots most dense on head and abdomen. Gill cover and peritoneum dark brown. Eye blue with white lens.

Distribution and biology. The holotype and only specimen was caught in a beam trawl at 390–394 m off Kimberley, Western Australia. In the same trawl-haul the following benthopelagic fish were taken (pers. comm. Martin Goman): Unidentified Congridae , Chlorophthalmus cf. acutifrons , Bregmaceros sp., Coelorinchus maculatus , Hymenocephalus longibarbis , Lucigadus ori , Chaunax sp., Phenacoscorpius sp., Plectrogenium sp., Malakichthys wakiyae , Bembrops sp., Kopua sp., Symphurus sp.

Etymology. The specific name refers to the regional locality of the type specimen.

Figures

FIGURE 1. Benthocometes australiensis, holotype. NMV A 29728 - 016. SL 93 mm.

FIGURE 2. Anterior, right gill arch: A. Benthocometes australiensis, holotype. B. Benthocometes robustus. ZMUC P 77683, SL 95 mm.

FIGURE 3. Pattern of vomerine and palatine dentition: A. Benthocometes australiensis, holotype. B. Benthocometes robustus. USNM 396083. SL 103 mm.

FIGURE 4. Right sagitta of Benthocometes australiensis (left scale bar), holotype: A. Median view, B. Anterior view, C. Dorsal view and of Benthocometes robustus (right scale bar), ZMUC P 77683, SL 95 mm: D. Median view.

FIGURE 6. Benthocometes robustus, bumphead. ZMUC P 77791, SL 78 mm. Off Cuba. (Arrow indicates head pore in midline of snout).

Tables

TABLE 1. Meristic and morphometric characters of Benthocometes australiensis and robustus.

	B. austra- liensis holotype	West Atlantic 13 spms.	Benthocometes robustus “Bump- East Atlantic Total 29 heads* 12 spms. specimens** 4 spms.	No.
SL, mm	93	57–110	59–95 20–123 20–123	29
Meristic characters
Dorsal fin rays	98	93–111	96–107 94–107 93(100.8)111	29
Predorsal pterygiophores	4	7–10	8–10 7–9 7(8.6)10	23
Caudal fin rays	11	11	11 11 11	27
Anal fin rays	80	78–92	84–94 82–91 78(86.1)94	29
Pectoral fin rays	30	28–31	30–31 28–32 28(29.8)32	26
Pelvic fin rays	2	2	2 2 2	29
Precaudal vertebrae	12	11–12	11 11–12 11(11.2)12	29
Total vertebrae	50	48–50	48–50 47–50 47(49.0)50	29
Dorsal fin origin above vertebra no.	3	6	6–7 6 6(6.0)7	27
Anal fin origin below dorsal fin ray no.	24	17–20	17–18 17–20 17(18.4)20	27
Anal fin origin below vertebra no.	15	13–15	13–14 14–16 13(14.4)16	29
Long gill rakers	3	10–12	9–10 9–11 9(10.5)12	22
Pseudobranchial filaments	7–8	6–7	6–7 6–8 6(6.6)8	20
Morphometric characters
Head length	23.0	20.0–23.5	22.0–25.0 21.5–22.5 20.0(21.9)25.0	19
Depth at anal fin origin	22.5	17.0–21.5	17.0–20.5 19.0–21.5 17.0(19.2)21.5	17
Upper jaw length	8.7	11.5–12.5	11.5–12.0 11.0–13.0 11.0(11.7)13.0	19
Diameter of eye window	5.7	5.4–6.9	5.8–6.4 5.5–6.7 5.4(6.1)6.9	19
Interorbital width	5.1	5.4–6.3	5.4–6.4 5.1–5.9 5.1(5.8)6.4	13
Postorbital length	13.0	10.5–12.5	11.0–12.0 11.0–13.0 10.5(11.7)13.0	17
Preanal length	46.0	40.5–47.0	41.0–45.0 41.0–46.0 40.5(43.7)47.0	19
Predorsal length	22.0	26.5–31.0	27.5–28.0 27.0–31.0 26.5(28.9)31.0	19
From base of pelvic to anal fin origin	25.0	22.0–27.5	24.5–25.5 24.0–26.5 22.0(24.7)27.5	17
Pectoral fin length	14.0	10.5–12.0	10.5–12.5 9.5–13.0 9.5(11.2)13.0	17
Pelvic fin length	14.0	9.1–12.5	11.0–11.5 9.8–11.5 9.1(10.7)12.5	15
Snout to post. end of lateral line	79	79–86	75–83 74–82 74(79.8)86	12