Parascombrops nakayamai Schwarzhans & Prokofiev, new species
Creators: name: Schwarzhans, Werner W.
name: Prokofiev, Artem M.
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Perciformes
Acropomatidae
Parascombrops
Parascombrops nakayamai

description: Parascombrops nakayamai Schwarzhans & Prokofiev, new species
Figs. 7F, 8C, 9F, 12B, 13F, 14O – R, 21, 27, 37, Tables 2–7
Material examined (62 specimens). Holotype BSKU 102255, 97 mm SL, Japan, Tosa Bay, Mimase fish market near Kochi. Paratypes: AMS I.24449-014, 10 specimens, 80–93.5 mm SL, 18°53’S, 116°10’E, 450 m, RV Solea, 30. Jan. 1984; BSKU 16825, 81 mm SL, 09°34’S, 128°08’E, 295–296 m, RV Hakuho-maru, 19. Aug. 1992; CAS 34870, 81.5 mm SL, 13°44’N, 120°41’E, 214–247 m, J.E. Norton, 5. Aug. 1966; CAS 236019, 84 mm SL, 13°48’N to 13°50’N, 120°24’E, 216–261 m, crew of DA-BFAR, 0 4. Jun. 2011; CAS 238017, 4 specimens, 76–84 mm SL, 14°41’N, 123°24’E to 14°42’N, 123°21’E, 435–451 m, Iwamoto et al., 27. Sep. 1995; MNHN 1995-0570, 4 specimens, 63–88 mm SL, 11°54’S, 179°31’W, 597–600 m, Musorstom 7: stn CP627, 29. May, 1992; MNHN 1995-0574, 2 specimens, 103–108 mm SL and MNHN 1995 -0575, 3 specimens, 106–109 mm SL, 12°16’S, 177°28’W, 780–794 m, Musorstom 7: stn CC553, 18. May 1992; MNHN 1998-0993, 3 specimens, 100–103 mm SL, 16°33’S, 167°55’E, 602–620 m, Musorstom 8: stn CC1056, 0 1. Oct. 1994; MNHN 2005-0934, 2 specimens, 58–104 mm SL, 11°12’N, 124°02’E, Musorstom 3: stn cp145, 0 7. Jun. 1985; MNHN 2009-0780, 83 mm SL, 16°13’S, 167°18’E, 627–655 m, BOAI: stn CP2456, 12. Sep. 2005; NMMB-P2851, 79.5 mm SL, Dong-gang, Pingtung, southwestern Taiwan; NMMB-P11346, 2 specimens, 83–85.5 mm SL, Dong-gang, Pingtung, southwestern Taiwan; NMMB-P14362, 84 mm SL, Dong-gang, Pingtung, southwestern Taiwan; NMMB-P22083, 2 specimens, 86.5–92.5 mm SL, Dong-gang, Pingtung, southwestern Taiwan; NMMB-P23092, 8 specimens, 85–108 mm SL, Dong-gang, Pingtung, southwestern Taiwan; NMMB-P23094, 2 specimens, 67–73 mm SL, Donggang, Pingtung, southwestern Taiwan; USNM 99303, 106 mm SL, 08°60’N, 124°60’E, 413 m, Albatross Expedition, 0 4. Aug. 1909; USNM 99315, 2 specimens, 88–110 mm SL, 11°17’N, 124°28’E, 333 m, Albatross Expedition, 16. Mar. 1909; ZMUC P44338–47, 10 specimens, 85–97 mm SL, donated from NMMB, Dong-gang, Pingtung, southwestern Taiwan.
Diagnosis. Slender species with flat dorsal head profile and pointed snout. Anal fin II + 7. Pectoral fin with 15–16 rays, pectoral length 19.5–24.3% SL. Gill rakers 11–16, decreasing with size. Pseudobranchial filaments 16–29, increasing in number with fish growth. First anal-fin pterygiophore long, slightly bent, with moderately broad, hollow tip. Vomer V-shaped with reduced dentition with only few long teeth near sides of base. Palatine with 1 row of teeth, anteriorly long, posteriorly granular; ectopterygoid widened, with 3–4 rows of granular teeth. Orbital diameter 9.5–12.6% SL, decreasing with size; snout length 87–113 % of orbital diameter. No longitudinal ridges on preopercular lobe. Otolith moderately slender (OL:OH = 1.7–1.8).
Description. Counts and measurements (see also summary Tables 2–7). Counts: D1: IX; D2: I + 8–9; A: II + 7; V: I + 5; P: 16 (15–17); developed gill rakers 14 (11–14, and up to 16 in specimens smaller than 60 mm SL); pseudobranchial filaments 26 (20–29, and down to 16 in specimens smaller than 60 mm SL). Morphometrics (% of SL): orbit 10.0 (9.5–12.6); snout 9.8 (9.5–11.5, down to 8.0 in specimens smaller than 60 mm SL); head length 39.5 (37.5–42.6); pectoral length 22.5 (19.5–24.3); maximal body depth 24.5 (20.9–25.6); predorsal length 39.8 (38.2–42.6); preventral length 36.6 (32.5–38.3); preanal length 68.2 (59.4–68.8). Snout long, sharply pointed; interorbital space almost flat. Posterior edge of maxillary concave with postero-dorsal and postero-ventral angles broadly rounded and postero-ventral angle extended downward and slightly backward resulting in slightly oblique posterior rim of maxillary. This character is much less developed in small specimens, which possess a posteroventral angle only slightly extended downward, and an almost vertical posterior rim of the maxillary plate. Preopercular lobe without longitudinal ridges, but denticles of hind margin serration extending into well-developed crests on preopercular lobe; inner edge of preopercle with 2–5 denticles. Proximal-middle radial of first anal fin pterygiophore long, slightly curved distally, with moderately broad hollow tip, reaching parapophyses of last abdominal vertebra. First haemal spine with weak posterior expansion. Pelvic fin spine serrated along its outer edge; all other fin spines smooth. About 25–27 scales along lateral line system.
Dentition. Premaxillary with a pair of strong canines near symphysis, followed posteriorly by a wide band of minute granular teeth. Dentary with a pair of strong canines, and a band of small conical teeth near symphysis, followed posteriorly by a row of small conical teeth and 2–5 enlarged canine-like teeth on each side. Vomer Vshaped, with reduced dentition. Anterior portion usually toothless, sometimes with very few minute granular teeth, and posterior portion with 2–3 widely spaced conical teeth. Palatine with 1 row of teeth, anteriorly long, posteriorly granular; ectopterygoid slightly expanded, with 2–3 rows of granular teeth. Tongue without teeth.
Otolith morphology (n = 18). Otolith elongate, thin, up to about 8 mm length. OL:OH = 1.7–1.8; OL:OT about 6–7. Dorsal rim with broad, very shallow medio-dorsal angle and marked, often sharp postdorsal angle close to posterior rim, often followed by notch. Ventral rim moderately deep, deepest slightly in front of its middle, below collum of sulcus. Rostrum well developed, sharply pointed; no or only weak excisura and antirostrum. Posterior rim blunt, with angle at junction with ventral rim significantly below tip of cauda. Dorsal and posterior rims smooth or slightly crenulated; ventral rim smooth. Inner face slightly convex with slightly supramedian positioned sulcus. Sulcus shallow, with posteriorly slightly widened, long cauda and wide, shallow ostium. Ostium about twice as wide as cauda, with distinct colliculum. Cauda with rounded, slightly bent tip, terminating close to posterior tip of otolith. CaL:OsL = 1.0–1.25. Dorsal depression wide. Ventral furrow distinct, close to ventral rim of otolith anteriorly and running parallel to ventral otolith rim and at some distance in its middle and posterior section and leading to tip of cauda. Outer face flat to slightly concave, smooth, with few short radial furrows near dorsal rim.
Coloration (in alcohol). Preserved fishes uniformly pale. Upper half of head including snout and anterior portion of lower jaw dark. Upper half of trunk, remainder of head and fins with numerous small dotted evenly distributed melanophores; large melanophores along lateral line pores. First dorsal fin with black tip over first three to four spines. Mouth pale, with patch of large melanophores on roof of mouth. Branchial cavity and peritoneum dark.
Size. Moderately large fishes reaching sizes up to about 110 mm SL.
Discussion. Parascombrops nakayamai is best recognized by the slender head and sharply pointed snout, about as long as the orbital diameter, the reduced dentition on the vomer, and the ectopterygoid being wider, slightly spatulate, and with more teeth rows (3–4) than the palatine (1–2). Smaller specimens (75–90 mm of SL) tend to have 1 or 2 rows of granular teeth on the vomer, while in larger specimens this is reduced to a few isolated granular teeth or none. The dentition pattern is only shared with P. yamanouei n. sp., which however differs in a less slender body, maximal body depth 28–34% SL; mean 31.5% SL, (vs 23–27% SL; mean 24.3% SL), the snout shorter than the orbit (vs equally long), and the compressed otoliths OL:OH = 1.5–1.6 (vs 1.7–1.8). Parascombrops nakayamai resembles closest P. argyreus and P. philippinensis. In addition, it differs from P. argyreus in the absence of longitudinal ridges on the preopercular lobe, the lower number of gill rakers in specimens of comparable size (Fig. 21) and the greater head length (37.9–42.6% SL vs 32.6–38.3% SL). It can be distinguished from P. philippinensis by the lower number of gill rakers, 11–15 (vs 15–18).
Geographic and bathymetric distribution. Parascombrops nakayamai appears to be widely distributed in the Western Pacific, known from southern Japan, Taiwan, the northern Philippines, to the Timor Sea off northwestern Australia, off Vanuatu and Wallis and Futuna at depths between 216 and 794 m.
Etymology. Named in honor of Naohide Nakayama (Laboratory of Marine Biology, Faculty of Science, Kochi University, Japan), who was the first to recognize the difference of this species based on a specimen collected from the Tosa Bay from P. philippinensis.
description: Published as part of Schwarzhans, Werner W. & Prokofiev, Artem M., 2017, Reappraisal of Synagrops Günther, 1887 with rehabilitation and revision of Parascombrops Alcock, 1889 including description of seven new species and two new genera (Perciformes: Acropomatidae), pp. 1-74 in Zootaxa 4260 (1) on pages 39-41, DOI: 10.5281/zenodo.571305