Diagnosis: Adult males of Hemibates koningsi can be distinguished from H. stenosoma, the only congener, by a flank colour pattern of four to seven black vertical bars, two to three flank-scales wide, on the anterior flank region and five horizontal bands, one to two, rarely three flank-scales high, on the posterior flank region vs. black blotches of variable number, size and shape at the anterior part of the flanks and five, rarely four, horizontal bands in H. stenosoma; they can further be distinguished by the fourth horizontal band, counted from dorsal to ventral, starting below pectoral fin base sometimes before and extending to caudal fin base in H. koningsi vs. normally ending well before caudal fin base in H. stenosoma; moreover, both species exhibit a black band on dorsal fin membrane along the dorsal-fin base, which is however wider and more pronounced in H. koningsi males (Ref. 117350). Females as well as males of H. koningsi can be unambiguously separated from H. stenosoma by their longer lower pharyngeal jaw, 37.6-38.2% of head length vs. 27.8-32.5%, with a characteristically curved keel, distinctive bulge ventrally of the keel, which contrasts with the more or less straight keel of H. stenosoma, which is only rounded towards the tip; meristics and measurements of Hemibates koningsi overlap with those of H. stenosoma, but H. koningsi on average has fewer gill rakers on the first gill arch, 33-37 vs. 35-43; it tend to have longer lower jaws, 44.0-47.1% of head length vs. 39.22-45.9%, longer upper lips, 32.6-36.7% of head length vs. 27.6-33.6%, and longer lower lips, 34.5-37.8% of head length vs. 30.1-36.0% (Ref. 117350).

Description: Laterally compressed and relatively deep-bodied species with maximum body depth slightly behind dorsal-fin origin, 31.6-34.8% of standard length, decreasing towards caudal peduncle; ratio of caudal peduncle length to depth 1.55-1.92; head length about one third of standard length; dorsal head profile moderately concave with slightly visible premaxillary pedicel prominence; no nuchal gibbosity present (Ref. 117350). Eyes round, eye diameter less than one third of head length, 26.2-31.1% of head length, and larger than interorbital width; jaws isognathous to slightly prognathous, lower jaw slightly protruding and comparatively narrow; mouth strongly oblique; posterior tip of maxilla not reaching level of eye; lower lip anteriorly wider than upper lip; lips not noticeably enlarged or thickened; lachrymal with five sensory-canal pores (Ref. 117350). Two separate lateral lines; flanks and dorsum covered with relatively large weakly ctenoid scales; anterior base of some flank scales covered with minute, cycloid or weakly ctenoid scales; cycloid scales of ventral belly region smaller than on flanks; cycloid chest scales, especially ventrally, smaller than flank scales; smallest scales on isthmus; snout scaleless; interorbital, nape and occipital region with slightly smaller scales than on flanks; cheeks covered by one to three rows of cycloid scales about size of ventral belly scales; operculum covered with ovoid and cycloid scales of variable size, small to about size of flank scales; three to six scales on vertical line starting from edge of posterior-dorsal angle of operculum to anterior edge of operculum; caudal fin scales small and becoming minute more caudally; scaled area may extend to more than half of the caudal fin (Ref. 117350). Upper lateral line with 58-69 scales, lower lateral line with 35-43 scales and horizontal line with 60-65 scales plus one to three pored scales on caudal fin; upper and lower lateral lines separated by three scales; seven to eight scales between dorsal-fin origin and upper lateral line; 28-32 scales around caudal peduncle (Ref. 117350). Anterior teeth of outer row of lower and upper jaw unicuspid and widely and irregularly set; teeth becoming smaller, less widely spaced and more regularly set towards mouth angle; individual unicuspid teeth comparatively slender and slightly recurved with acutely pointed brownish crowns; outer row of upper jaw with 67-84 teeth and outer row of lower jaw with 48-67 teeth in specimens between 99.9-217.4 mm standard length; neither number of teeth in the lower jaw nor of the upper jaw is significantly correlated with standard length; unicuspid teeth of inner tooth rows smaller than those of outer rows, upper jaw with one or two inner tooth rows and lower jaw with single inner tooth row (Ref. 117350). Lower pharyngeal bone about 1.8-2.1 times longer than broad; width of dentigerous area of lower pharyngeal bone 0.3-0.4 times length of lower pharyngeal bone length, with 26-27 teeth along posterior margin of dentigerous area; individual teeth slender, beveled, with its labial side featuring several cusp protuberances, and always with a pointed major cusp; lower pharyngeal jaw teeth largest along posterior margin of dentigerous area and becoming smaller towards the keel, anterior teeth slender and beveled sometimes unicuspid; keel of lower pharyngeal bone characteristically curved with distinctive bulge on ventral keel (Ref. 117350). Total gill raker count 33-37, with 6-8 epibranchials, one angle and 26-28 ceratobranchial rakers; individual rakers long and slender; smallest rakers anterior of ceratobranchial increasing in size towards cartilaginous plug; gill raker of cartilaginous plug smaller than neighbouring ceratobranchial rakers; epibranchial rakers decreasing in size dorsally (Ref. 117350). Dorsal fin with 14-15 spines and 13-15 rays; first dorsal-fin spine shortest; dorsal-fin base length 47.6-50.5% of standard length; dorsal-fin rays of mature males extending to around level of caudal fin base whereas in young males, less than 106 mm standard length, and in females rays only extending to around the first half of caudal peduncle; anal-fin rays not reaching caudal fin base in young males and in females, but reaching about first half of caudal peduncle; anal fin with 3 spines and 12-14 rays; third anal-fin spine longest; anal-fin base shorter than pectoral-fin length, 17.9-19.8% of standard length and 27.5-30.7% respectively; pectoral fin with 13 or 14 rays; longest pectoral-fin ray, fifth ray counted from dorsally to ventrally, more or less slightly exceeding level of anus; pelvic-fin base posterior to pectoral-fin base, separated by roughly three to five flank scale widths; pelvic fin with one spine and five rays; first pelvic-fin ray longest, variably elongated in mature males, either terminating slightly before anal-fin origin or exceeding it slightly; in females and young males only slightly exceeding level of anus; caudal-fin outline furcate and composed of 34-36 rays, 16 principal caudal fin rays and 18-20 procurrent caudal fin rays (Ref. 117350). Total vertebrae 33-34, excluding the urostyle, with 16-17 abdominal and 17-18 caudal vertebrae; pterygiophore supporting the last dorsal-fin spine located between the neural spines of the thirteenth and fourteenth vertebrae or of the fourteenth and fifteenth vertebrae; pterygiophore supporting the last anal-fin spine located between hemal spines of seventeenth and eighteenth vertebrae, rarely between rips of the fourteenth vertebrae and hemal spine of the fifteenth vertebrae; one single predorsal bone present; hypurals 1 and 2 and hypurals 3 and 4 always fused into a single seamless unit (Ref. 117350).

Colouration: Colouration in life: pronounced sexual colour dimorphism present (Ref. 117350). Males with distinct colour pattern of black vertical bars, between 2 and 3 flank-scales wide, and horizontal bands, betwee 1 and 2, rarely 3 flank-scales high; body ground colouration silvery-whitish; iris of eyes whitish with dusky areas; cheeks, operculum and dorsum of freshly caught specimens sometimes in light purplish iridescent; dorsal head surface, dorsal area of nape and area just below dorsal fin base dusky greyish-brown; preorbital area whitish to dusky; cheek with blackish horizontal stripe of variable shape and width below eye; second horizontal stripe on ventral part of preoperculum, intraoperculum, and lower jaw, fused at the mental area with corresponding stripe of other side; area between those stripes whitish including ventral area between lower jaws and ventral parts of branchiostegal membrane; operculum and suboperculum with two blackish vertical elements of variable shape and width; four to seven blackish vertical bars at anterior part of flanks with first bar situated just behind gill cover; if seven vertical bars shape of most posterior bar blotchlike; five horizontal bands present; dorsalmost one in most specimens shortest starting on the level of first, anterior, dorsal-fin ray or behind it, extending to caudal fin base and dorsal caudal peduncle area, there fusing with the horizontal band of the other side; second and third horizontal band, counted from dorsal to ventral, commencing anterior to dorsalmost horizontal band; third band sometimes commencing before second horizontal band and extending to caudal fin base; fourth horizontal band commencing below pectoral-fin base, sometimes even before, and extending to caudal fin base while fusing ventrally of caudal peduncle with the corresponding band of other side; most ventral horizontal band extending from gill cover to the anal fin base; vertical bars in most cases ventrally fused with horizontal bands; dorsal-fin membrane with black band along base, commencing at level of third or fourth dorsal-fin spine and extending to soft-rayed area of dorsal fin; above this black band, a smaller whitish or turquoise iridescent band; margin of dorsal-fin membrane black; anal-fin membrane with blackish or whitish areas of variable extent; soft rayed part with one to three conspicuous markings; eggspot-like markings of ovoid shape and of greyish to whitish colour and a blackish outline; caudal-fin membrane white with black horizontal elements, which might be partially fused; pectoral fin whitish hyaline; pelvic fin whitish to greyish, posterior part of rays black (Ref. 117350). Females almost entirely silvery white without any striking colour pattern; cheeks, operculum and dorsum of freshly caught specimens iridescent light purple; chest and belly whitish; iris of eye whitish; dorsal head surface, dorsal area of nape and areas just below dorsal-fin base dusky, light greyish-brown to silvery, but less prominent than in males; anal, pelvic and pectoral whitish; caudal fin whitish to dusky; dorsal fin membrane whitish to dusky, margin of membrane between tips of spines and rays darkish (Ref. 117350). Colouration of juveniles unknown; subadult males with a less contrasting flank colouration than adult males, with vertical bars only slightly visible and horizontal bands almost invisible (Ref. 117350). Colouration in alcohol: overall colour pattern of vertical bars, horizontal bands, and head stripe elements comparable to fresh male specimens but dark brown; body ground colouration in male and female beige, only ventral region might appear whitish; dorsal head surface brownish (Ref. 117350).