Parascombrops ohei 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 ohei

description: Parascombrops ohei Schwarzhans & Prokofiev, new species
Figs. 2C, 6G, 7G, 9H, 13G, 14S – U, 22, 37, Tables 2–7
Material examined (8 specimens). Holotype BSKU 72614, 75 mm SL, Japan, Tosa Bay, 33°14’N, 133°38’E, 172– 215 m. Paratypes: BSKU 9951, 53.5 mm SL, no data; BSKU 63370-71, 2 specimens, 82.5–87 mm SL, Japan, Tosa Bay, Mimase fish market near Kochi; BSKU 87909, 74.5 mm SL, Japan, Tosa Bay Kuroshio Town, 200 m; BSKU 116497-98, 2 specimens, 64–77.5 mm SL, Japan, Tosa Bay, Mimase fish market near Kochi; NSMT P59841, 70.5 mm SL, Japan, Tosa Bay, Mimase fish market near Kochi.
Diagnosis. Moderately slender species with convex dorsal head profile and bluntly rounded snout. Anal fin with 2 spines and 7 soft rays, first ray being segmented, but not branched (Fig. 6G). Pectoral fin with 14–15 rays, pectoral length 23.1–26.6% SL. Gill rakers 13–16. Pseudobranchial filaments 19–25. First anal-fin pterygiophore long, straight, with sharply pointed tip, not hollow. Vomer triangular, broad, with many granular teeth. Palatine and ectopterygoid broad, with 2–4 granular teeth rows. Orbital diameter 10.7–12.3% SL. One or two longitudinal ridges on preopercular lobe. Otolith very slender (OL:OH = 1.9–2.1).
Description. Counts and measurements (see also summary Tables 2–7). Counts: D1: VIII–IX; D2: I + 9; A: II + 7; V: I + 5; P: 14 (14–15); developed gill rakers 14 (13–16); pseudobranchial filaments 24 (19–25). Morphometrics (% of SL): orbit 12.0 (10.7–12.3); snout 7.7 (7.0–9.8); head length 36.9 (34.1–37.7); pectoral length 24.6 (23.1–26.6); maximal body depth 27.7 (21.5–27.7); predorsal length 37.4 (35.5–40.3); preventral length 31.3 (31.3–36.4); preanal length 65.8 (65.0–66.7). Snout short, rounded; interorbital space convex. 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. Preopercular lobe with one or two longitudinal ridges, hind margin serrations not extending into crests on preopercular lobe; inner edge of preopercle with 3–5 denticles. First soft anal fin-ray segmented, but not branched. Proximal-middle radial of first anal-fin pterygiophore long, straight, with sharply pointed tip, not hollow, ending in space between last abdominal and first caudal vertebrae. First haemal spine with a very slight posterior expansion. Pelvic fin spine serrated along its outer edge; all other fin spines smooth.
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 by a row of small conical teeth and 2–4 enlarged canine-like teeth on each side. Vomer triangular, broad, with many granular teeth, few or no longer teeth at rear margin. Palatine and ectopterygoid broad, with 2–4 granular tooth rows. Tongue without teeth.
Otolith morphology (n = 7). Otolith very elongate, thin, up to about 8 mm length. OL:OH = 1.9–2.1; OL:OT about 8–9. Dorsal rim shallow, nearly horizontal except for very feeble mediodorsal bulge; postdorsal angle rounded, positioned far backwards very close to posterior rim. Ventral rim shallow, deepest slightly in front of its middle, below collum of sulcus. Rostrum well developed, moderately sharply pointed; weak excisura and antirostrum. Posterior rim blunt, short, with angle at junction with ventral rim at 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 long cauda and moderately wide, shallow ostium. Ostium distinctly less than twice as wide as cauda, with distinct colliculum. Cauda with rounded, distinctly downward bent tip, terminating close to posterior tip of otolith. CaL:OsL = 1.1–1.25. Dorsal depression long, narrow. Ventral furrow distinct, close to ventral rim of otolith anteriorly and slightly turning upwards posteriorly towards tip of cauda. Outer face slightly concave, smooth, with few short radial furrows near dorsal rim.
Coloration. Preserved fishes a uniform pale coloration, with few small melanophores scattered over body. Snout, occiput and tip of first dorsal fin over first 4 spines dark. Patches of small melanophores on dorsal fins, caudal fin, upper part of opercle, rear part of maxillary and tip of lower jaw. Scale pockets of upper half of body with intensely dark colored rims. Mouth pale. Branchial cavity dark anteriorly and with small patch of melanophores behind pseudobranchial filaments; peritoneum dark.
Size. Fishes reaching sizes up to about 90 mm SL.
Discussion. Parascombrops ohei is a slender species (maximum body depth 21.5–25.7% SL) with a rounded head profile and snout. The species is best identified by the unique characters of very slender otoliths (OL:OH = 1.9–2.1), and the presence of a segmented, unbranched first soft anal-fin ray at all sizes. It is distinguished from P. nakayamai in the short, rounded snout (vs. long and pointed), the presence of longitudinal ridges on the preopercular lobe (vs. absent), the slender, sharply pointed and not hollow first anal-fin pterygiophore (vs. slightly curved distally, with moderately broad hollow tip), the broad vomer with many granular teeth (vs reduced with only few long teeth along the rear margin), and the broad palatine with 2–3 rows of granular teeth (vs 1 row). It differs from P. philippinensis in the more rounded head profile, the presence of longitudinal ridges on the preopercular lobe (vs. absent), the slender, sharply pointed and not hollow first anal-fin pterygiophore (vs. broad, with hollow tip), the slender otolith (OL:OH = 1.9–2.1 vs. 1.6–1.85), and the broad palatine and ectopterygoid. It resembles P. argyreus in the morphology of the first anal-fin pterygiophore, shape of the maxillary plate and the presence of longitudinal ridges on the preopercular lobe, but differs in the lower number of pseudobranchial filaments in specimens of similar size, 19–25 (vs 26–38), the strongly convex head profile, the slender otolith and the broader palatine tooth band. The presence of an unbranched segmented first soft anal-fin ray in P. ohei n. sp. is reminiscent of the emergent 3rd anal-fin spine of P. analis. However, there is an abundance of differentiating characters between these species (see diagnoses and key), and we therefore regard the development of the weak third anal spine as homoplastic.
Geographic and bathymetric distribution. Parascombrops ohei appears to be endemic to southern Japan, and so far has only been caught in Tosa Bay at about 200 m depth. Fossil otoliths of P. ohei are known from the Late Pliocene Dainichi Sand of Kakegawa, Shizuoka Prefecture, further to the North-East of the Tosa Bay.
Etymology. Named in honor of Fumio Ohe, Seto (near Nagoya, Japan), the otolith specialist who first recognized the presence of a hitherto unrecorded species of Parascombrops in the Pliocene record of Japan.
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 41-43, DOI: 10.5281/zenodo.571305