Parascombrops nakayamai

description

Description. Counts and measurements (see also summary Tables 2 – 7). Counts: D 1: IX; D 2: 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 ma

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)

diagnosis

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).

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)

discussion

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

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)

etymology

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.

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)