Lestidium nigrirostrum, Ho & Graham & Russell, 2020

Ho, Hsuan-Ching, Graham, Ken & Russell, Barry, 2020, Three new species of the barracudina genus Lestidium (Aulopiformes: Paralepididae) from the Indo-West Pacific, Zootaxa 4767 (1), pp. 71-88 : 78-81

Lestidium nigrirostrum sp. nov.

urn:lsid:zoobank.org:act:5C95A762-A737-46ED-984B-169E5F5400E1

Australian Robust Barracudina

Figs. 3 A–E, 4A, 5A; Tables 1–2

Holotype. CSIRO H 1159-16 , 316 mm SL, 17°30.1’S, 150°41.2’E, Marian Plateau , ENE of Townsville, Queensland northeastern Australia, Southwestern Pacific Ocean, demersal trawl, 752– 751 m, 24 Nov. 1985.

Paratypes. Twenty-two specimens, 195–338 mm SL. AMS I.19202-004 (6 specimens, 242–264 mm SL), 33°11’S 152°20’E, 50 km SE of Newcastle, New South Wales, Australia, demersal trawl 600 m, FRV Kapala, 11 May 1976, coll. K Graham. AMS I.25825-001 (1, 324), 18°00’S, 147°06’E, 120 km N of Townsville, Queensland, Australia, demersal trawl 300 m, RV Soela, 16 Jan. 1986, coll. M. McGrouther and S. Reader. AMS I.25836-003 (1, 308), 17°59’S, 147°07’E, 125 km N of Townsville, Queensland, Australia, demersal trawl 305 m, RV Soela, 20 Jan. 1986, coll. M. McGrouther and S Reader. AMS I.26393-002 (5, 218–245), 33°44’S, 151°52’E, 70 km ENE of Sydney, New South Wales, Australia, demer- sal trawl 525 m, FRV Kapala, 4 Nov. 1985, coll. K. Graham. AMS I.27594-009 (1, 216), 36°38’S, 156°11’E, near Gascoyne Seamount, Tasman Sea, midwater trawl 520 m, 15 March 1988, coll. N. Klaer. AMS I.40005-001 (1, 338), 36°12’S 150°24’E, 15 km E of Montague I. New South Wales, Australia, demersal trawl 520 m, FV Shelley H, 1 March 2000, coll K. Graham. NMV A.7122 (1, 195), 33°43’S, 151°52’E, Broken Bay, New South Wales, Australia, 420 m, 24 Jan. 1982 NMV A.7661 (1, 203), 34°27’S, 151°18’E, off Wollongong, Tasman Sea, New South Wales, Australia, 280 m, 22 Jan.1982 CSIRO H616-27 (1, 314), CSIRO H616-28 (1, 317), CSIRO H616-29 (1, 313), CSIRO H616-30 (1, 317), CSIRO H616-31 (1, 325) 19°0.7’S, 150°41.2’E, northeast of Whitsunday group, Marian Plateau, demersal trawl, 752– 751 m, 24 Nov. 1985.

Non-types. AMS I.15967-004 (1, 205), FRV Kapala, 33°42’S, 151°52’E, 60 km ENE of Sydney, New South Wales, demersal trawl, 280 m, 6 Apr. 1971. AMS I.15977-003 (1, 258), FRV Kapala, 29°54’S, 153°40’E, 40 km E of Wooli, New South Wales demersal trawl 380 m, 12 May 1971. AMS I.17879-007 (1, 191), FRV Kapala, 33°50’S, 151°36’E, 30 km E of Sydney New South Wales, midwater trawl 0-110 m, 2 Jul. 1973, coll. K. Graham. AMS I.19206-002 (1, 233), FRV Kapala, 33°29’S 152°03’E, 60 km E of Terrigal, New South Wales, Australia, demersal trawl 495 m, 27 May 1976, coll. K. Graham. AMS I.20518-017 (1, 250), FRV Kapala, 28°00’S, 153°59’E, 55 km E of Gold Coast, Queensland, Australia, demersal trawl 550 m, 2 Jun. 1978, coll. K. Graham. AMS I.22642-002 (1, 167), FRV Kapala, 32°08’S, 153°04’E, 55 km E of Tuncurry, New South Wales, demersal trawl 495 m, 27 July 1981, coll. K. Graham. AMS I.23488-002 (1, 287), FRV Kapala, 33°40’S 150°56’E, 55 km ESE of Broken Bay, New South Wales, demersal trawl 510 m, 13 Oct. 1982, coll. K. Graham. AMS I.25288-015. (1, 95), FRV Kapala, 35°14’S, 151°54’E, 30 km SE of Jervis Bay, New South Wales, midwater trawl 0-110 m (bottom depth 220m), 1 May 1980, coll. K. Graham. AMS I.25814-002 (1, 126), RV Soela, 17°55’S, 147°06’E, 90 km E of Mission Beach, Queensland, demersal trawl 260 m, 13 Jan. 1986, coll. M. McGrouther and S. Reader. AMS I.25816-005 (1, 305), RV Soela, 17°57’S, 147°02’E, 100 km E of Mission Beach, Queensland, demersal trawl 300 m, 13 Jan. 1986, coll M. McGrouther and S. Reader. AMS I.26029-003 (1, 162), FRV Kapala, 33°44’S, 151°52’E, 65 km off Broken Bay, New South Wales, demersal trawl 525 m, 4 Nov. 1985, coll. K. Graham. AMS I.29738-005 (1, 285), FRV Kapala, 31°54’S, 153°12’E 45 km ESE of Crowdy Head, New South Wales, demersal trawl 500-900 m, 13 Oct. 1982, coll. K. Graham. AMS I.33318-001 (18, 159–185), AMS I.33318-002 (16), FV Imlay, 37°04’S, 150°18’E, 40 km off Eden, New South Wales, demersal trawl

400 m, 1992, coll. R. Drenkhahn. AMS I.38508-001 (1, 210), 37°40’S, 150°15’E, 35 km SE of Gabi I., Victoria, demersal trawl 440 m, FRV Kapala, 29 April 1997, coll. K. Graham. CSIRO A4289 (1, 171), 37°27’S, 150°15’E, east of Cape Howe, midwater trawl, 138–150 m, 6 Feb. 1977. CSIRO B1246 (2, 158–217), 36°03’S, 150°21’E, northeast of Narooma midwater trawl, 79–90 m, 31 Mar. 1976. CSIRO CA 860 (1, 230), 37°39’S, 150°15’E, southeast of Gabo Island, Midwater trawl, 20–40 m, 18 Apr. 1977.

Tentatively identified. CSIRO H 2128-002 (1, 242), 17°50’S, 150°41.2’E, southwest of Rowley Shoals, Western Australia, 420 m, bottom trawl, 12 Feb. 1989.

Diagnosis. A species in the Lestidium prolixum species complex with a complete lateral-line, and a simple luminescent duct originating below opercle; it can be further distinguished from two other congeners in the species complex in having 31–34 anal-fin rays; prehaemal vertebrae 35–38 and total vertebrae 87–90; lateral-line ended at caudal fin base, with 142–157 scales; DFO clearly behind tip of adpressed pelvic fin, V–D 5.6–8.5%SL and 28.6–38.6%V–A; 5–7 lateral-line scales and 4–7 vertebrae between VFO and DFO; dorsum dark brownish, mela

nophores extending downward to the lateral-line along its entire upper margin; anterior portions of snout and lower jaw blackish; abdomen with a very broad black sub-margin.

Description. Dorsal-fin rays 10; pectoral-fin rays 13 (12–14); pelvic-fin rays 9; anal-fin rays 34 (31–34). Lateral-line scales: prepelvic 34 (33–36); predorsal 40 (39–42); preanal 54 (53–57); and total 150 (142–157). Vertebrae: prehaemal 36 (35–38); caudal 52 (50–53); prepelvic 35 (34–36); predorsal 41 (40–41); preanal 54 (54–56); and total 88 (87–90).

Body relatively elongate, robust and less compressed; belly slightly convex in profile; greatest depth of body at approximately anterior third of body, body depth at pectoral-fin base 14 (13–17) times in SL. Caudal peduncle short, about 1.3–1.5 times eye diameter. Dorsal adipose fin small. A moderately constricted abdominal ridge between head and pelvic fins. Ventral adipose fin slightly developed on abdominal ridge and moderately developed along margin between anus and AFO. Anus at about tip of adpressed pelvic fin, slightly in front of DFO.

DFO clearly behind VFO and midpoint of SL ( Figs. 4A ), well before midpoint of V–A; predorsal length 1.6 (1.6) in SL. Pectoral-fin base at same vertical as posterior margin of gill cover, its upper base about same horizontal of lower margin of eye.A small pocket behind pectoral-fin base. VFO well behind midpoint of SL, prepelvic length 1.8 (1.8–1.9) in SL, with a small axial scale behind pelvic fin base. Anal fin originating at posterior fourth of body, preanal length 1.3 (1.3) in SL. Anal-fin base 5.6 (5.6–6.1) in SL. Adipose fin above rear portion of anal-fin base. Head moderately long and stout, slightly wider at opercle than body, its length 4.8 (4.6–4.9) in SL. Snout moderately long and blunt, its length 2.0 (1.9–2.0) in HL. Postorbital length slightly less than third of HL. Mouth terminal, moderately large, its gape extending to level of anterior margin of eye or slightly beyond; tip of lower jaw upturned distally, with a small fleshy process on its tip. Eye moderately large, its diameter 6.8 (5.9–6.8) in HL. No light organ in front of eye; a luminescent duct at lower margin of orbit.

Interorbital space narrow, its width 9.6 (9.0–11.7) in HL; some straight ridges on top of head and snout. Upper jaw length 2.1 (2.0–2.1) in HL, posterior end of maxilla extending to about one-third eye diameter before a vertical from orbit. Two nostrils close together, about one-third eye diameter before posterior end of maxilla. Sensory canals on snout, check, operculum, and jaws; numerous sensory pores on dorsal surface of snout and lower surface of lower jaw.

Opercle thin, with posterior margin bluntly pointed, its lower margin notched around base of pectoral fin. Gill membranes joined far forward, before a vertical from eye, free from isthmus.

Five gill arches, filament present on the first to fourth arches and absent on fifth; fourth arch mostly connected to the gill wall by membrane; pseudobranchs present, inside a deep pocket.

Two to 4 small fangs at tip of upper jaw, followed by numerous small retrorse teeth in a single row along the upper jaw, these gradually becoming smaller posteriorly. Three fixed or depressible fangs at/on front of lower jaw, followed by two rows of fangs forming 6–8 tooth pairs, those in inner row long with knife-like tips and depressible; those in inner row much shorter, recurved and fixed. Vomerine teeth absent. Two rows of fangs on each palatine, the anterior 5–6 teeth form- ing widely-spaced tooth pairs; those in the outer row long and depressible; teeth in the inner row small and fixed; posterior portion with single row of small fixed teeth. One row of small straight, teeth on each side of tongue.

Gill rakers present on epibranchial, ceratobanchial and hypobanchial of first gill arch; the rakers shield shaped, each with 2–4 small teeth and a narrow base. Rakers on epibranchial of first arch 12 (10–14), ceratobranchial with 19 (17–22), hypobranchial with 16 (12–17), total rakers 47 (40–50). Teeth on pharyngeal arch slender, forming an oval patch with about 5 rows at middle/centre. Single row of small teeth on fifth ceratobranchial.

Body devoid of scales, except for a single row along the lateral-line originating above pectoral girdle and extending to caudal-fin base. Anterior 65 (63–66) scales on lateral line are clearly larger in size, with lengths about equal to height and gradually becoming smaller and narrower posteriorly; followed by 85 (79–97) distinctly smaller scales from above posterior half of anal-fin base to caudal fin. Larger scales with a cluster of 4–6 (usually 5) large pores on each margin, the first one larger than the rest and a median pore on center of broader of these larger scales; a pore on upper and lower end of the distinctly smaller scales.

A well-developed, unbranched, elongate luminescent duct along the mid-line of the ventral margin, extending anteriorly from the anus to below opercle ( Fig. 3D ).

Coloration. Preserved specimens ( Figs. 3 , 4A , 5A ) dark brownish on dorsum, pale ventrally; melanophores on dorsum extending downward to entire lateral line, gradually becoming scattered along the posterior third of lateral line; dense melanophores on top of head, snout, lips, orbit ( Figs. 3B, C ); lower surface/underside of lower jaw covered with scattered melanophores ( Fig. 3D ); abdomen with pale margin and a broad black sub-margin ( Figs. 3A , 5A ); pectoral and pelvic fins covered with scattered melanophores; dorsal, adipose, anal and caudal fins densely covered with choromatophores; gill chamber mostly black with broad pale margin on gill cover; branchiostegal membrane and isthmus uniformly black; peritoneal membrane black, all sections fused in adults. Fresh color unknown.

Size. The largest specimen examined was 338 mm TL.

Etymology. The specific name is derived from Latin niger and rostrum, in referring to the black snout.

Distribution. The species is currently known from waters off eastern Australia, ranging from the Coral Sea off central Queensland to Bass Strait and into the Tasman Sea.

Remarks. The species is one of three species recognized in the Lestidium prolixum complex having a large body size, a complete lateral line extending to caudal fin base, a luminescent duct on the lower margin of orbit, DFO behind VFO, but well before midpoint of V–A; and more than 126 lateral-line scales.

It differs from L. prolixum in having the DFO slightly, but clearly behind the tip of adpressed pelvic fin and anus (vs. overlapped with the adpressed pelvic fin and above anus in L. prolixum , Fig. 4B ). Related to this character are V–D 28.6–38.6% (vs. 18.4–25.5%) of V–A; lateral-line scales between VFO and DFO 5–7 (vs. 3–4, rarely 5). Moreover, the melanophores on the dorsum extend downward to the lateral line in L. nigr orostrum, but e x t end only to the upper margin of the lateral line and form a wavy line in L. prolixum ( Fig. 5A vs. 5B). Lestidium nigrorostrum also reaches a large adult body size (338 mm SL), whereas the largest specimen of L. prolixum examined was 276 mm SL ( Ho et al., 2019a).

Specimens from Western Australia, very similar to this new species, have a much lighter body coloration and shorter body, and possibly represent a different species. Pending more detailed investigation, we exclude these specimens from the type series here.

Figures

FIGURE 3. Lestidium nigrorostrum sp. nov., holotype, CSIRO H1159-16, 316 mm SL. A. Lateral view. B. Lateral view head. C. Dorsal view of head. D. Ventral view of head, arrow indicates the anterior end of luminescent duct. E. Lateral view tail region, arrow indicates the posterior end of lateral line.

FIGURE 4. Posterior region of trunk showing the fin position. A. L. nigrorostrum sp. nov., from the holotype. B. L. prolixum, NMMB-P25552, 276 mm SL. C. L. rofeni sp. nov., one of paratypes, catalog number unknown. Bars indicate DFO (upper), tip of pelvic fin (ventral left) and AFO (right).

FIGURE 5. Anterior trunk region showing the pigmentation.A. L. nigrorostrum sp. nov., from the holotype, arrow indicates the upper margin of lateral line.B. L. prolixum, NMMB-P25552, 276 mm SL, arrow indicates the dots along upper margin of lateral line. C. L. rofeni sp. nov. from the holotype, arrow indicates the unpigmented region above lateral line.