Parascombrops Alcock, 1889

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), Zootaxa 4260 (1), pp. 1-74 : 17-18

Genus Parascombrops Alcock, 1889

Type-species: Parascombrops pellucidus Alcock, 1889

Maccullochina Jordan, 1922 (type-species: Synagrops serratospinosa Smith & Radcliffe, 1912 )

Diagnosis. A genus unique by a combination of the 7th and 8th dorsal-fin pterygiophores correspond to the 7th interneural gap and the 8th interneural gap vacant, and the predorsal formula /0+0/0+2/; and distinctive in the following combination of additional characters: pelvic-fin spine with regular sharp serrations along its outer margin from base to tip; D1 with 9 spines, all well-developed and visible externally; D2 with 8–9 branched rays; anal-fin ray formula II + 7 or III + 6; distal element of last D1 pterygiophore enlarged, elongated and overlying along anterior face of the first D2 pterygiophore; epaxialis attachment type 1; no basiocipital fossa and otophysic connection, no posterior opening of myodome; cranial crests strong, W-shaped; preopercle with denticles at inner margin and with or without crossing ridges on lobe; ectopterygoid toothed; first epural bent anteriad, with ample space between the neural processes of the 2nd and 3rd preural vertebrae.

Description. Small to moderately large fishes reaching maximum SL of slightly more than 70 mm for the smallest species, and more than 180 mm for the largest ( P. argyreus ). Body laterally compressed, with highly deciduous scales, rarely seen in preserved specimens, scales extending onto bases of caudal fin, bases of soft portions of second dorsal and anal fins, and cheeks. Dorsal surface of head naked. Two clearly separated dorsal fins; soft dorsal and anal fins short-based. Caudal fin forked. Mouth oblique, lower jaw protruding, upper jaw reaching middle to posterior third of orbit. Jaws with canine teeth at least at symphyses, but commonly also laterally on mandibles. Vomer and palatines toothed, ectopterygoid with small denticles; tongue usually without teeth (present only in P. glossodon n. sp.). Nasal openings close to each other, and to anterior rim of the orbit; posterior nasal opening much larger than anterior. Preopercle with double edge; inner edge with denticles; hind margin serrated. Hind margin of lower part of subopercle and of interopercle weakly to moderately serrated, rarely almost smooth. Opercle with two weak spines, the lower extended as weak flap.

Cranial roof bones strongly sculptured; cranial crests strong, contiguous, W-shaped. Otic region of skull unmodified: no basioccipital fossa and no posterior opening of myodome; anterior part of swimbladder not reaching cranium. Suborbital shelf narrow, spine-like. Three supraneurals; predorsal formula /0+0/0+2/. Vertebrae 10 + 15. Pleural ribs from third to tenth vertebrae; parapophyses from 7th – 10th vertebrae, gradually increasing in length. Caudal vertebrae with distinct dorsal and ventral prezygapophyses, increasing in strength caudally. Caudal skeleton with five autogenous hypurals, an autogenous parhypural, three epurals and well-developed second uroneural.

Otoliths thin, compressed to elongate (OL:OH = 1.35–2.1), with ventral rim more deeply curved than dorsal rim. Rostrum distinct, antirostrum and excisura absent or feeble. Sulcus typical heterosulcoid with anteriorly opened ostium and posteriorly only slightly bent cauda terminating close to posterior tip of otolith. Ostium about twice as wide as cauda, shallower, with distinct colliculum, and slightly shorter than cauda (CaL:OsL = 1.0–1.35). Ventral furrow typically bent upwards posteriorly to terminate close to posterior tip of cauda.

Discussion. Parascombrops is easily identified by the pterygiophore/interneural pattern below D1 (7th and 8th dorsal-fin pterygiophores correspond to the 7th interneural gap, and the 8th interneural gap being vacant), which is an autapomorphy of this genus, and by the strongly serrated pelvic fin spine, a character only shared with Caraibops and which is considered a synapomorphy for both genera. The pterygiophore formula of Parascombrops (/0+0/0+2/) is unique amongst acropomatids, most of which possesses a pattern 0/0/0+2/, with exception of Kaperangus (with /0/0+2/). Also Parascombrops is the only genus in the Acropomatidae with type 1 epaxial insertion (vs type 2 in Synagrops and Neoscombrops cynodon , and type 0 in the all other genera in the family). Parascombrops further differs from Caraibops n. gen. in the lower number of branched rays in D2 (8–9 vs 10) and in the anal fin (6–7 vs 9), in the inner rim of the preopercle bearing denticles, in the much stronger cranial crests, and in the presence of denticles on the ectopterygoid. Parascombrops further differs from Synagrops having a serrated pelvic fin spine, the absence of a basioccipital fossa and a posterior opening of the myodome, and the shape of the otolith and the sulcus (see Synagrops for description). For a detailed comparison with Kaperangus see above.

Species and distribution. Parascombrops is the most specious genus in the family Acropomatidae , with 13 extant species here regarded as valid, and is distributed throughout the tropical and subtropical Indo West-Pacific and the Western Atlantic . It appears absent from the Eastern Atlantic and the Eastern Pacific . The species recognized as valid are: P. analis ( Katayama, 1957) , P. argyreus ( Gilbert & Cramer, 1897) , P. glossodon n. sp., P. madagascariensis n. sp., P. mochizukii n. sp., P. nakayamai n. sp., P. ohei n. sp., P. parvidens n. sp., P. pellucidus Alcock, 1889 (with Synagrops adeni Kotthaus, 1970 as a synonym), P. philippinensis ( Günther, 1880) (with Synagrops malayanus Weber, 1913 as a synonym), P. serratospinosus ( Smith & Radcliffe, 1912) , P. spinosus ( Schultz, 1940) and P. yamanouei n. sp. In addition there are a number of fossil otolith-based species that are considered to represent Parascombrops , i.e. at least P. brzobohatyi Nolf, 1988 from the Late Eocene of the Aquitaine Basin , France and P. epigonoides Nolf & Brzobohaty, 2002 from the Early Miocene of the Aquitaine Basin , France, plus a number of undescribed species known to the first author and a few extant species also known as fossils ( P. argyreus and P. ohei ).