Phenacoscorpius longilineatus, Motomura & Causse & Struthers, 2012

Motomura, Hiroyuki, Causse, Romain & Struthers, Carl D., 2012, Phenacoscorpius longilineatus, a New Species of Deepwater Scorpionfish from the Southwestern Pacific Ocean and the First Records of Phenacoscorpius adenensis from the Pacific Ocean (Teleostei: Scorpaenidae), Species Diversity 17 (2), pp. 151-160 : 152-156

Phenacoscorpius longilineatus n. sp.

[New English name: Southern No-line Scorpionfish] ( Fig. 1 )

Phenacoscorpius sp. 1: Motomura et al. 2011a: 64 ( New Caledonia).

Holotype. MNHN 2010-0942 , 83.7 mm SL, New Caledonia, Norfolk Ridge , 23°39′00″S, 168°01′01″E, 345 m, Aztèque cruise, Station no. 3, RV Alis, bottom trawl, 13 February 1990.

Paratypes. 93 specimens, 30.5–104.9 mm SL. NEW CALEDONIA: MNHN 2000-1471 , 53.1 mm SL, 23°40′00″S, 167°45′00″E, 470 m, RV Coriolis, 30 October 1986; MNHN 2003-1524 , 2 , 70.4–88.1 mm SL, Norfolk Ridge, 23°42′00″S, 168°15′00″E, 378–402 m, RV Alis, 12 August 1999; MNHN 2003-1531 , 2 , 61.6–93.2 mm SL, 23°43′01″S, 168°16′01″E, 379–391 m, RV Alis, 12 August 1999; MNHN 2003-1543 , 10 , 30.5–66.1 mm SL, Norfolk Ridge, 24°52′08″S, 168°21′07″E, 518–540 m, RV Alis, 11 August 1999; MNHN 2004-2559, 102.1 mm SL, Norfolk Ridge, 23°44′10″S, 168°17′20″E, 377–401 m, RV Alis, 31 October 2003; MNHN 2004-2578 , 87.4 mm SL, Norfolk Ridge, 23°43′08″S, 168°16′23″E, 380–389 m, RV Alis, 23 October 2003; MNHN 2004- 2680 , 16 , 33.5–91.2 mm SL, Norfolk Ridge, 24°57′47″S, 168°21′07″E, 627–1089 m, RV Alis, 28 October 2003; MNHN 2004-2790 , 5 , 70.4–97.5 mm SL, Norfolk Ridge, 23°48′54″S, 168°16′01″E, 500–1074 m, RV Alis, 31 October 2003; MNHN 2004-2841 , 91.6 mm SL, Norfolk Ridge, 23°44′06″S, 168°16′08″E, 390–398 m, RV Alis, 31 October 2003; MNHN 2005-2593 , 3 , 34.5–35.9 mm SL, 24°55′59″S, 168°21′00″E, 560 m, RV Alis, 7 March 1989; MNHN 2005-2659 , 9 , 72.0– 94.7 mm SL, 23°37′59″S, 167°42′00″E, 463 m, RV Alis, 14 February 1990; MNHN 2005-2660 , 2 , 69.9–85.1 mm SL, 24°54′S, 168°21′E, 530 m, RV Vauban, 20 May 1987; MNHN 2010-0941 , 89.5 mm SL, 23°39′00″S, 168°01′01″E, 345 m, RV Alis, 13 February 1990; MNHN 2011-0089 , 14 , 39.6–71.4 mm SL, 22°58′59″S, 168°22′01″E, 490–515 m, RV Vauban, 29 September 1985; MNHN 2011- 0165 , 49.3 mm SL, same data as MNHN 2003-1524; MNHN 2011-0166 , 2 , 56.0– 71.6 mm SL, same data as MNHN 2005-2659; MNHN 2011-0167 , 5 , 45.2–58.6 mm SL, same data as MNHN 2005-2660; NMNZ P . 029073, 57.0 mm SL, Aztèque Seamount , 23°19′24″S, 168°00′20″E, 580–600 m, C . Roberts and C . Paulin , 22 October 1992; NMNZ P . 029210, 3, 43.8–66.3 mm SL, a seamount, 24°55′30″S, 168°21′27″E, 540–670 m, C. Roberts and C . Paulin , 15 October 1992; NMNZ P . 029337, 3, 69.5–74.2 mm SL, Jumeaux Seamount , 23°48′45″S, 168°17′06″E, 540–950m, C . Roberts and C . Paulin , 21 October 1992; NMNZ P . 029350, 2, 86.9–90.2 mm SL, Jumeaux Seamount , 23°44′54″S, 168°16′45″E, 390– 400 m, C . Roberts and C . Paulin , 21 October 1992; NMNZ P . 029380, 95.6 mm SL, Jumeaux Seamount , 23°42′39″S, 168°16′10″E, 390–420 m, C . Roberts and C . Paulin , 21 October 1992; KAUM –I . 48325, 104.9 mm SL, KAUM –I. 48326, 84.7 mm SL, KAUM –I. 48327, 76.1 mm SL, KAUM –I. 48328, 39.3 mm SL, Bellona Reef , Chesterfield Islands, 22°10′59″S, 159°24′00″E, 350–370 m, RV Coriolis, 16 July 1984; KAUM –I . 48362, 72.3 mm SL, same data as MNHN 2003-1543 . NEW ZEALAND: NMNZ P . 038308, 62.7 mm SL, Rumble 5 Submarine Volcano, North Island, 36°08′24″S, 178°11′24″E, 360–755 m, RV Tangaroa , 24 May 2001; NMNZ P . 039610, 70.1 mm SL, southern Norfolk Ridge , 34°37′26″S, 168°57′34″E, 521–539 m, RV Tangaroa , 3 June 2003 .

Diagnosis. A species of Indo–Pacific Phenacoscorpius with the following combination of characters: 16–18 (mode 17) pectoral fin rays, middle rays branched in young and adults; 8–18 (mode 12) pored lateral-line scales, with last pored scale situated from below base of seventh spine to below base of fourth dorsal-fin soft ray; 50–52 scale rows in longitudinal series; 18–21 (mode 20) gill rakers; no slit behind fourth gill arch; palatine teeth present; second preopercular spine always absent; nuchal and parietal spines distinct; 4–6 (mode 5) suborbital spines in young and adults, 6–7 in larger adults; nape and anterior part of body strongly arched in adults of over ca. 80 mm SL; relatively long postnuchal-spine length, 5.0–9.7% (mean 7.2%) of SL; relatively short caudal fin length, 21.4–26.7% (mean 23.4%) of SL; 1–5 (mode 2) black spots on posterior half of caudal peduncle; body usually uniformly whitish without distinct dark saddles in preserved specimens; largest recorded specimen 105 mm SL.

Description. Counts and measurements (as percentages of SL) of P. longilineatus are given in Table 1. Frequency distributions of selected meristics are presented in Table 2. In the description below (including the colour description of preserved specimens), the data and description of the holotype are presented first, followed by data for paratypes in parentheses when different.

Body moderately compressed anteriorly, progressively more compressed posteriorly. Nape and anterior part of body strongly arched (moderately arched in young and juveniles). Body moderately deep, but body depth less than head length. Uppermost ray (upper 2 rays in juveniles) and lower 9 (7–10) rays of pectoral fin unbranched, remaining rays branched (all rays of smallest paratype, 30.5 mm SL, unbranched); 10th (10th to 12th) ray longest. Third (or second) soft ray longest among dorsal fin rays. Second soft ray longest among pelvic and anal fin rays. Supraocular tentacle slender and short (but often absent); no other distinct tentacles on body. No distinct papillae on body. No fimbriate flap on posterior lacrimal spine. Pectoral fin axil without skin flap. Cycloid and ctenoid scales covering opercle, cheek, area surrounded by orbit, suborbital ridge, ascending ramus of preopercle, nuchal spine, and lower posttemporal spine. Ctenoid scales covering interorbital and occiput regions; other parts of head not covered with scales. Well-exposed ctenoid scales covering lateral surface of body; exposed cycloid scales on anteroventral surface of body. Exposed cycloid and ctenoid scales covering pectoral fin base. Body scales not extending onto rays or membranes of fins, except for bases of pectoral and caudal fins. Lateral line incomplete; last pored lateral-line scale situated from below base of ninth dorsal-fin spine (from below base of seventh spine to base of fourth dorsal-fin soft ray).

Mouth large, slightly oblique, forming angle of about 20 degrees to longitudinal axis of head and body. Posterior margin of maxilla extending beyond vertical drawn through posterior margin of pupil, but not reaching to vertical drawn through posterior margin of orbit. Lateral surface of maxilla smooth, without ridges, tentacles, or scales. Lower jaw with symphyseal knob. Width of symphyseal gap separating premaxillary teeth bands subequal to width of each band. Upper jaw with band of villiform teeth. Tooth band of upper jaw wider than that of lower jaw. Lower jaw with band of villiform teeth, length of most teeth equal to those of upper jaw. Vomer and palatines with villiform teeth; maximum width of vomerine tooth plate subequal to maximum length of palatine tooth plate. Underside of dentary with 3 sensory pores on each side, first pore below anterior lacrimal ridge, second pore below posterior lacrimal spine, third pore located on posterior margin of dentary. Pore behind symphyseal knob of lower jaw on each side. Underside of lower jaw smooth, without ridges or tentacles. No slit behind fourth gill arch. Swimbladder present. Vertebrae 25.

Dorsal profile of snout steep, forming angle of about 60 (50–60) degrees to longitudinal axis of head and body. Nasal spine simple, somewhat conical, directed upward. Anterior nostril with low membranous tube, latter bearing slender, short tentacle. Ascending process of premaxilla not intruding into interorbital space, its posterior margin extending slightly beyond level of posterior margin of posterior nostril. Median interorbital ridge absent. Interorbital ridges poorly developed, separated by shallow channel, beginning posterior to nasal spines and not conjoined. No distinct ridge on anterior edge of occiput. Interorbital ridges diverging anteriorly and posteriorly in dorsal view, space between them narrowest at level of anterior margin of pupil. Interorbital space shallow, only about one-tenth of orbit extending above dorsal profile of head. Preocular spine simple, direct- ed nearly upward. Supraocular spine simple, its tip located above middle of eye. Postocular spine simple, slightly longer than tympanic spine. Tympanic spine simple; bases of tympanic spines barely joined with interorbital ridges. Coronal, interorbital, and pretympanic spines absent. Occiput nearly flat. No distinct transverse ridge at rear of occiput. Occiput bordered laterally by tympanic and parietal spines. Nuchal and parietal spines joined to each other at bases, but still two distinct spines. Sphenotic with small spines. Pterotic spine simple. Upper posttemporal spine and ridge absent. Lower posttemporal spine simple, its base longer (often shorter) than that of pterotic spine. Supracleithral and cleithral spines flattened and rounded with pointed tips.

Lateral lacrimal spine present (but absent on left side of head in MNHN 2004-2804; absent on both sides of head in MNHN 2004-2790, 1 of 5 specimens, 71.5 mm SL). Anterior lacrimal spine indistinct, not pointed but rounded; no additional spines at anterior base of lacrimal spine. Posterior lacrimal spine simple, not strongly pointed, triangular, its tip not reaching upper jaw lip. Posterior lacrimal spine smaller than anterior spine. Suborbital ridge with 7 spines on both sides of head (4–7 spines), first spine below middle of eye. Preopercle with 4 spines, uppermost spine largest with supplemental preopercular spine on its base, second spine absent, third to fifth spines without median ridge. Preopercle without serrae or spines between uppermost preopercular spine and its own upper end. Upper opercular spine simple without median ridge. Lower opercular spine simple with distinct median ridge. Space between upper and lower opercular spines not covered with fleshy skin. Posterior tips of upper and lower opercular spines not reaching opercular margin.

Origin of first dorsal fin spine above supracleithral spine base. Posterior margin of opercular membrane extending beyond vertical drawn through origin of fourth (often third) dorsal fin spine. Posterior tip of pectoral fin reaching vertical drawn through anterior base of soft-rayed portion of dorsal fin. Posterior tip of depressed pelvic fin extending beyond anus. Origin of pelvic fin spine slightly anterior to origin of pectoral fin. Origin of first anal fin spine just below origin of last dorsal fin spine.

Colour of preserved specimens. Body uniformly white, except for black eyes and spots on caudal peduncle (rarely with 4 pale black saddles on body; first above opercle, second below posterior part of spinous portion of dorsal fin, third below soft-rayed portion of dorsal fin, and fourth on caudal peduncle). Three tiny black spots (1–5 spots) on posterior half of caudal peduncle. Pale black blotch (usually distinct but absent in presumed females) on spinous portion of dorsal fin between seventh and eleventh spines.

Colour when fresh. Colour of holotype unknown. In one paratype, body and fins pale red, mottled with poorly defined white or pinkish blotches (based on colour photograph of NMNZ P. 039610, paratype, 70.1 mm SL: Fig. 1B ).

Distribution. This species is known from the southwestern Pacific Ocean where it ranges from New Caledonia south to northern New Zealand. The type series was collected in depths of 345–1089 m. The Muséum national d’Histoire naturelle in Paris holds an enormous collection of deepwater trawled fishes, including scorpionfishes, from the Pacific Ocean, which we have examined ( Motomura et al. 2011a), but no specimens of P. longilineatus were collected in surveys in the Philippines (surveyed in 1976, 1980, 1985), Indonesia (1991), the Marquesas Islands (1997, 2002), the Solomon Islands (2000, 2004), Taiwan (2000, 2001), French Polynesia (2002, 2009), and the Austral Islands (2002). This indicates that the species is restricted to the southwestern Pacific Ocean.

Etymology. The specific name longilineatus is derived from Latin meaning “long line”, in reference to the long lateral line of the new species associated with the greatest number of pored lateral-line scales in the genus.

Remarks. Phenacoscorpius longilineatus can be distinguished easily from all of its congeners, including the Atlantic species Phenacoscorpius nebris Eschmeyer, 1965 , by having a higher number of pored lateral-line scales [8–18 (mode 12)], the last pored scale being located from below the seventh spine base to below the fourth dorsal-fin soft ray base [vs 2–8 (mode 3), with the last located from below the second to fifth dorsal-fin spine base; Mandrytsa 1992; Motomura 2008; Motomura and Last 2009; Motomura et al. 2012]. In the Indo–Pacific, P. longilineatus further differs from P. megalops Fowler, 1938 and P. longirostris Motomura and Last, 2009 by having teeth on the palatines (vs no such teeth in the latter two species: Motomura 2008; Motomura and Last 2009) and from P. eschmeyeri in having the nuchal and parietal spines distinct (vs fused to each other to form a single large spine: Motomura et al. 2012).

Phenacoscorpius longilineatus is most similar to P. adenensis , co-occurring in the southwestern Pacific Ocean. In addition to the number of pored lateral-line scales, P. longilineatus differs from P. adenensis in having a lower number of black spots on the posterior half of the caudal peduncle [1–5 (mode 2) vs 5–37 (8) in the latter: Table 2], a relatively longer post-nuchal-spine length [5.0–9.7% (mean 7.2%) of SL vs 3.2–9.5% (mean 5.7%): Table 1], a relatively shorter caudal fin length [21.4–26.7% (mean 23.4%) of SL vs 23.4– 30.7% (mean 26.7%): Table 1], the body usually uniformly whitish without distinct dark saddles in preserved specimens ( Fig. 1A, C–F ) vs usually with four dark saddles ( Fig. 2A–D ), and the nape and anterior body strongly arched in adults of over ca. 80 mm SL ( Fig. 1A, E, F ) vs not strongly arched throughout life ( Fig. 2A–D ).

Phenacoscorpius longilineatus has a black blotch on the posterior part of the spinous portion of the dorsal fin only in presumed males whereas P. adenensis has the blotch in both sexes (variation of blotch size and shape in P. adenensis is discussed below).

Phenacoscorpius longilineatus grows larger than P. adenensis (largest recorded size, 104.9 mm vs 79.6 mm SL). Although the number of the suborbital spines in both species is modally five, larger specimens of P. longilineatus tends to have more spines; three specimens with seven spines on both sides of the head, or asymmetrically six and seven spines, were of more than 90 mm SL ( Tables 1–2).

Figures

Fig. 1. Phenacoscorpius longilineatus n. sp. from the southwestern Pacific Ocean. A, MNHN 2010-0942, holotype, 83.7mm SL, New Caledonia; B, NMNZ P. 039610, paratype, fresh specimen, 70.1mm SL, New Zealand; C, NMNZ P. 029210, paratype, 43.8mm SL, New Caledonia; D, NMNZ P. 029210, paratype, 66.3mm SL, New Caledonia; E, NMNZ P. 029350, paratype, 86.9mm SL, New Caledonia; F, NMNZ P. 029380, paratype, 95.6mm SL, New Caledonia. The nape and anterior body are strongly arched in adults of over 80mm SL, i.e., A, E, F.

Fig. 2. Phenacoscorpius adenensis from the southwestern Pacific Ocean. A, MNHN 2001-2855, 34.3mm SL, Vanuatu; B, CSIRO H 6047-01, fresh specimen, 51.7mm SL, Australia; C, NMNZ P. 041914, 53.1mm SL, New Zealand; D, MNHN 2010-0827, 65.0mm SL, Vanuatu.