Parascombrops parvidens 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 parvidens

description: Parascombrops parvidens Schwarzhans & Prokofiev, new species
Figs. 7H, 8B, 9G, 11C, 13H, 14V – Y, 23, 37, Tables 2–7
Material examined (14 specimens). Holotype BSKU 98886, 57.5 mm SL, Indonesia, S of Sulawesi, 250–258 m, R/ V Hakuhonaru, KH 85-01, 12. – 13. Feb. 1985. Paratypes: BSKU 98883-84, 87– 90 mm SL, 7 specimens, 55.5–62 mm SL, same data as holotype; BSKU 15219-21, 3 specimens, 69–75 mm SL, 08°14’N, 119°59’E; USNM 436686, 3 specimens, 56–65 mm SL, 08°46’N, 123°32’E, Albatross Philippines Expedition, 0 9. Aug. 1909.
Diagnosis. Moderately slender, gracile species with convex dorsal head profile. Anal fin II + 7. Pectoral fin with 15–16 rays, pectoral length 26.2–30.4% SL, reaching anterior tip of anal fin. Gill rakers 18–20. Pseudobranchial filaments 16–21. First anal-fin pterygiophore long, straight, with broad tip and hollow. No canine teeth laterally on dentary. Vomer narrow, V-shaped, with 2–3 rows of granular teeth. Palatine broad, with 2 rows granular teeth; ectopterygoid narrow, with 1 row granular teeth. Orbital diameter 10.2–12.1% SL. One or two longitudinal ridges on preopercular lobe. Otolith moderately slender (OL:OH = 1.8–1.85).
Description. Counts and measurements (see also summary Tables 2–7). Counts: D1: IX; D2: I + 9; A: II + 7; V: I + 5; P: 16 (15–16); developed gill rakers 19 (18–20); pseudobranchial filaments 18 (17–21). Morphometrics (% of SL): orbit 11.7 (10.2–12.1); snout 9.9 (8.0–11.1); head length 40.0 (37.1–41.9); pectoral length 29.6 (26.2–30.4); maximal body depth 26.3 (24.8–27.3); predorsal length 39.0 (37.1–42.0); preventral length 37.7 (36.4–40.4); preanal length 68.2 (62.5–70.9). Snout short, rounded; interorbital space convex. Posterior edge of maxilla almost straight or very weakly concave with postero-dorsal and postero-ventral angles sharp to slightly rounded and postero-ventral angle somewhat extended downward but positioned at same level with postero-ventral angle resulting in an almost vertical posterior rim of the maxilla. Preopercular lobe with one or two longitudinal ridges, denticles of hind margin serration not extending into crests on preopercular lobe; inner edge of preopercle with 4–8 denticles. Proximal-middle radial of first anal-fin pterygiophore long, straight, with broad hollow tip, reaching last pair of pleural ribs. First haemal spine with a variably-developed posterior expansion (sometimes weak, sometimes bulge-like). Pelvic-fin spine serrated along its outer edge; all other fin spines smooth.
Dentition. Premaxilla with a pair of small canines near symphysis, followed posteriorly by a wide band of minute granular teeth. Dentary with a pair of minute canines, and a band of small conical teeth near symphysis, followed posteriorly by a row of small conical teeth without enlarged canines. Vomer narrow, V-shaped, with 2–3 rows of granular teeth. Palatine broad, with 2 rows, rarely 1 row of granular teeth; ectopterygoid narrow, short, with 1 row granular teeth. Tongue without teeth.
Otolith morphology (n = 5). Otolith moderately elongate, thin, up to about 5 mm length. OL:OH = 1.8–1.85; OL:OT about 8 to 10. Dorsal rim shallow, with broad, obtuse, mediodorsal angle and rounded, inferior postdorsal angle positioned at some distance from posterior tip. Ventral rim shallow, deepest slightly in front of its middle.
Rostrum well-developed, slender, sharply pointed; distinct but weak excisura and antirostrum. Posterior rim bluntly pointed, slightly below level of caudal tip. All rims smooth. Inner face very slightly convex, nearly flat, with slightly supramedian positioned sulcus. Sulcus moderately shallow, with long, deeper 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 = 1.05–1.15. Dorsal depression long, narrow. Ventral furrow distinct, close to ventral rim of otolith anteriorly and turning upwards posteriorly towards turning point of cauda. Outer face flat, smooth.
Coloration. Preserved fishes uniform pale in color. Upper half of body from tip of snout to peduncle, opercle and fins dusted with many small sparsely distributed melanophores. Scale pockets of upper half of body often with more intensely dark colored rims. Mouth pale, roof dark and area behind tongue dusted with small melanophores. Branchial cavity dark anteriorly and with small patch of melanophores behind pseudobranchial filaments; peritoneum dark.
Size. Small fishes reaching sizes up to about 75 mm SL.
Discussion. Parascombrops parvidens is a small species with a rounded head profile and snout, and is readily diagnosed by the lack of canine teeth on dentary otherwise typical for Parascombrops. It differs from P. philippinensis also in the presence of longitudinal ridges on the preopercular lobe, the higher number of gill rakers, 18–20 (vs 15–18) and the long pectoral fin, 26.2–30.4% SL (vs 21.5–27.2% SL) reaching the anterior edge of the anal fin (vs not reaching the anterior edge of the anal fin). It differs from P. ohei in the higher number of gill rakers, 18–20 (vs 13–16), the broadly tipped, hollow first anal-fin pterygiophore (vs sharply pointed and not hollow), the narrow ectopterygoid with only 1 row of small denticles (vs 2–4 rows) and the long pectoral fin, 26.2–30.4% SL (vs 23.1–26.6% SL) reaching the anterior edge of the anal fin (vs not reaching the anterior edge of the anal fin).
Geographic and bathymetric distribution. Parascombrops parvidens appears to be a holotropical species of the Western Pacific restricted to the southern Philippines and eastern Indonesia (off southern Sulawesi) at about 250 m depth.
Etymology. From the Latin parvus = small, and dens = tooth, referring to the absence of enlarged canines on dentary.
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 43-45, DOI: 10.5281/zenodo.571305