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Dorsal spines (total): 0-0; Dorsal soft rays (total): 15-17; Anal spines: 0-0; Anal soft rays: 11-12; Vertebrae: 42-43. Diagnosis: Eugnathichthys virgatus is unique among congeners in the possession of body pigmentation dominated by a broad lateral band intersected by numerous vertical bars resulting in a midlateral, checkerboard-like pigmentation patterning both in life and in preservation (Ref. 94471). Internally it is characterized by a marked reduction in dentition on the fifth ceratobranchial elements of the pharynx; externally it differs from congeners in the possession of a reduced total number of pectoral-fin rays, 13-15 vs. 16-18 (Ref. 94471). Eugnathichthys virgatus is further readily distinguished from E. eetveldii by the possession of 66-72 pored lateral line scales from opercle to caudal flexion vs. 96-103; 10-12 scale rows between the lateral line and the dorsal-fin origin vs. 14 or 15; and 8 or 9 scale rows between the lateral line and pelvic-fin insertion vs. 10 (Ref. 94471).It differs from E. macroterolepis in the possession of 8 or 9 scale rows between the lateral line and the pelvic-fin insertion vs. 6 or 7 (Ref. 94471).
Description: Relatively deep-bodied, body depth 18.0-24.4% of standard length, greatest depth at vertical midway between pectoral and pelvic-fin insertions; head length 29.0-31.3% of standard length, eyes large, bony orbit diameter 22.6-26.2% of head length (Ref. 94471). Dorsal head profile straight from snout to top of head, strongly convex over nape to dorsal-fin origin; dorsal body profile gently convex along dorsal-fin base to caudal-fin base; ventral body profile gently convex between isthmus and anal-fin base, caudal peduncle almost twice as long as deep (Ref. 94471). Snout elongate; mouth terminal and jaws relatively massive; contralateral premaxillae and dentaries immovably united by strongly interdigitating sutures (Ref. 94471). Upper and lower jaws both with two tooth rows; inner row teeth small, elongate bicuspids moveably implanted in a connective tissue sheath within replacement tooth trench; inner row tooth shafts horizontally oriented spanning tooth trench, recurved cusps vertically oriented; outer row teeth stout, erect and closely apposed bicuspids with flattened, expanded crowns each bearing a small, blunt anterior cusp and a prominent, enlarged posterior cusp (Ref. 94471). Premaxillae and dentaries each with 15-17 outer row teeth frimly ankylosed to anterior margin of replacement trench; premaxillary teeth overlie those on dentaries when mouth closed, resulting in a shearing bite (Ref. 94471). Dorsal fin with 3-4 unbranched and 12-13 branched rays; anal fin with 3 unbranched and 8 or 9 branched rays, with first unbranched rays diminutive, often clearly apparent only in x-rays or cleared and stained specimens (Ref. 94471). Dorsal-fin origin located well in advance of vertical through pelvic-fin insertion; first dorsal pterygiophore inserted between neural spines of vertebral centra 11 or 12 (Ref. 94471). Caudal fin deeply forked, upper lobe slightly longer than lower; principal caudal-fin rays 10+9 (Ref. 94471). Pectoral fin short and narrow, mean length 14.6% of head length; reduced number of 13-15 rays (Ref. 94471). Body covered with small, regularly imbricate, distally dentate scales (Ref. 94471). Lateral line complete, in straight midlateral line from opercle to anterior margin of caudal fin, 66-72 pored scales to caudal flexion, 10-12 scale rows between lateral line and dorsal-fin insertion, 8 or 9 between lateral line and pelvic-fin insertion, 24 or 25 circumpeduncular scales (Ref. 94471). Total of 9 or 10 gill rakers on ceratobranchial of first arch, rakers reduced to flattened toothplates along proximal portion of arch, becoming somewhat enlarged towards angle of arch (Ref. 94471). Tttothplates on fifth ceratobranchial elements of pharynx greatly reduced, restricted to distal margin of bone and dentition limited to 2 or 3 tooth rows (Ref. 94471).
Colouration: In preservation, base body coloration creamy brown, darker above midlateral line than below; snout, upper jaw, and top of head dark brown; well marked postorbital streak passing diagonally across infraorbital 4 onto posterior margin of opercle; lower jaw, cheek and branchiostegal membrane pale cream; one or two rows of irregular, often distinct, oblong blotches on nape; 12-14 vertically oriented oblong bars along midlateral line, bars extended onto dorsum from mid-body to caudal peduncle; vertical bars intersected medially by broad midlateral band resulting in characteristic checkerboard-like pigmentation patterning; dorsal fin pale, creamy white with three thin black stripes, adipose fin with black basal blotch and distal spotting; caudal fin with alternating black and white stripes; remaining fins creamy white (Ref. 94471). In life, base body coloration with slight pinkish hue; iridescent silver reflections on scales; head and body pigmentation patterning as for preserved specimens; markings on dorsal and caudal fin as in preserved specimens but interspaces between black bands bright orange-red; adipose fin pale orange with black spotting distally; remaining fins hyaline, with slight dusky overlay (Ref. 94471). |