Pterophycis spatium, Ho, 2019

Ho, Hsuan-Ching, 2019, A new genus and species of the cod fish family Moridae (Order Gadiiformes) from southwestern Taiwan, Zootaxa 4702 (1), pp. 32-40 : 32-40

Pterophycis spatium sp. nov.

New English name: Bigfin mora

New Chinese name: ƛñëḋ (Da-chi-zhi-shue)

Figs. 1A , 2A , 3 A–C, 4A–B

Holotype. NMMB-P22891 (243 mm SL), Ke-tzu-liao, Kaohsiung, southwestern Taiwan, western Taiwan Strait , purchased from fish market, collected by local bottom trawl, 4 May 2015.

Paratype. ASIZP 58039 (1, 210+ mm SL), Chong-chou , Kaohsiung, southwestern Taiwan, 1 Dec. 1985 .

Diagnosis. As given for the genus.

Description. The following data are given for the holotype, followed by the value of paratype in parentheses, when available. Characters given in the diagnosis of the genus are not repeated.

First dorsal-fin rays 8 (8), second dorsal-fin rays 67 (47+); pectoral-fin rays 27 (29); anal-fin rays 71 (47+); pelvic-fin rays 7 (7/5); scales in longitudinal series ca. 125 (ca. 105+); scale rows between first dorsal-fin base and lateral line 12 (11); gill rakers 3+8=11 (3+4=7); vertebrae 15+40=55.

Head length 4.0 times in SL; predorsal length 3.3; prepectoral length 3.7; prepelvic length 4.2; preanal length 2.7; dorsal-fin base 1.5; anal-fin base 1.5; pectoral-fin length 6.0; pelvic-fin length 4.1. Snout 3.3 (3.1) times in head length; eye diameter 4.0 (3.9); interorbital width 4.5 (4.3); upper-jaw length 2.2 (2.1); post-orbital length 1.9 (2.0); barbel 6.6 (6.5); longest first dorsal-fin ray 2.8 (2.8); longest second dorsal-fin ray 2.8; caudal-peduncle length 6.5; caudal-peduncle height 8.5.

Body moderately elongate, robust anteriorly, gradually compressed and narrowing to a narrow caudal peduncle and caudal fin. Head large and broadly rounded, slightly depressed anteriorly; snout wide with a round anterior outline; eye large, its diameter slightly wider than interorbital space. Mouth large and terminal; maxilla extends to a vertical near the posterior margin of eye; upper jaw slightly overhanging the lower jaw. Gill slit wide. Teeth villiform, in wide band on both jaws; vomerine and palatine toothless. Chin barbel present, its length shorter than eye diameter.

Two dorsal fins. Origin of first dorsal fin clearly behind a vertical of insertion of pectoral fin; origin of anal fin slightly behind a vertical of that of second dorsal fin; pectoral fin with broad base, rounded posteriorly, with lower rays gradually shorter; pelvic fin thoracic, extremely large, inserting slightly anterior to pectoral fin, when appressed, it tip extends to base of 15th (21st) ray of anal fin, all rays elongate, subequal in length; caudal fin small, well separated from dorsal and anal fins, rounded and symmetrical posteriorly. Caudal peduncle short, its length less than eye diameter.

Scales cycloid, small, oval-shaped; scale patch extends to anterior nostril and below middle of eye; naked area on snout large, not reaching to middle of eye. Gular region and branchiostegal membrane naked. Scales in front of pelvic-fin base gradually smaller anteriorly.

Luminous organ large, distance between its anterior and posterior margins 12.7% (22.0%) of distance between interventral line and origin of anal fin (InV-af); its locality closer to interventral line than anus (at middle point of interventral line and anus in paratype), distance between interventral line and anterior margin of light organ (InV- LO) 21.7% (29.8%) of InV-af; anus large and rounded, circled by black naked skin, situating slightly closer to interventral line than origin of anal fin (at middle point of interventral line and origin of anal fin in paratype); genital papilla separated posteriorly from anus by several small scales.

Coloration. When fresh body reddish brown and trunk blue-tan; branchiostegal membrane black; first dorsal fin and pectoral- and pelvic- fin bases darker; second dorsal and anal fins with indistinct black margins. The preserved holotype is darker than its fresh condition overall. The long-term preserved paratype lost most of its coloration; head light brown; gular region, branchiostegal membranes, naked area of snout and outer margins of dorsal and anal fins deep brownish, with all other portions of body creamy white.

Distribution. Only known from the shallow waters (less than 100 m) in southwestern Taiwan off Kaohsiung, western Taiwan Strait, southwestern Taiwan.

Etymology. The specific name spatium , means distance in Latin, is referred to the clear gape between the anus and genital papilla, which is unique for the family.

Figures

FIGURE 1. Ventral view of abdominal region comparing with the pelvic fins, light organ (left arrow), anus (middle arrow) and genital papilla (right arrow). A. Pterophycis gen. nov., NMMB-P22891. B. Holotype of Physiculus dalwigkii, type species of Physiculus, MNHN 1996-1380, 190 mm SL. C. Physiculus chigodarana, NMMB-P16401, 118 mm SL.

FIGURE 2. Dorsolateral view of head showing the anterior extension of swimbladder (arrowed). A. Pterophycis gen. nov., NMMB-P22891. B. Physiculus dalwigkii, type species of Physiculus, MNHN A.4502, 197 mm SL.

FIGURE 3. Pterophycis spatium sp. nov., holotype, NMMB-P22891, 243 mm SL. A. Lateral view. B. Ventral view of head. C. Lateral view of head.