Johnius, Bloch, 1793

Hanafi, Norhafiz, Chen, Meng-Hsien, Seah, Ying Giat, Chang, Chih-Wei, Liu, Shang Yin Vanson & Chao, Ning Labbish, 2022, Johnius sasakii, a new species of croaker (Perciformes: Sciaenidae) with a key to Johnius from East Malaysia, Borneo, Zootaxa 5116 (3), pp. 393-409 : 406-407

Key to the species of Johnius in the East Malaysia (Northern Borneo)

1a. Distinctly enlarged teeth on upper jaw and inner row of lower jaw teeth enlarged, conical J. ( Johnieops ) ( Fig. 1 (A))...... 2

1b. Slightly enlarged teeth on upper jaw and inner row of lower jaw teeth uniform in size or molariform J. ( Johnius ) ( Fig. 1 (B)). ................................................................................................... 3

2a. First pair of mental pores separated by symphysis, snout rounded; second anal-fin spine length 40–50% of head length................................................................................ J. plagiostoma (Bleeker, 1850)

2b. First pair of mental pores by a crescent-shaped groove, snout pointed; second anal-fin spine length 24–42% of head length............................................................................... J. borneensis (Bleeker, 1850)

3a. Chin with barbel............................................................ J. amblycephalus (Bleeker, 1855)

3b. Chin without barbel................................................................................... 4

4a. Dorsal-fin spines VIII or IX (usually IX); scale rows above lateral line from dorsal-fin origin 10–15, scale rows below lateral line from anal-fin origin 17–21................................................ J. trachycephalus (Bleeker, 1850)

4b. Dorsal-fin spines IX to XI (usually X); scale rows above lateral line from dorsal-fin origin 4–11, scale rows below lateral line from anal-fin origin 6–17............................................................................... 5

5a. Scales moderately small, scale rows above lateral line from dorsal-fin origin 7–11; scale rows below lateral line from anal-fin origin 11–17......................................................................................... 6

5b. Scales moderately large, scale rows above lateral line from dorsal-fin origin 4–8 (usually 5–6), scale rows below lateral line from anal-fin origin 6–14 (usually 6–10)................................................................... 9

6a. Body dark pigmented; lower fins black............................................... J. belangerii (Cuvier, 1830)

6b. Body silvery to light yellow; lower fins pale................................................................ 7

7a. Gill rakers slender, 9–12 on lower limb gill arch and moderately long ½–⅔ length of gill filaments at angle of arch........................................................................................ J. coitor (Hamilton, 1822)

7b. Gill rakers stiff, 7–9 on lower limb of gill arch and short ⅓–½ length of gill filaments at angle of arch.................. 8

8a. Body depth 25–30% of standard length; second anal-fin spine length short, stiff, 26–32% of head length.................................................................................................. J. latifrons Sasaki, 1992

8b. Body depth 20–25% of standard length; second anal-fin spine length long, stiff, 33–41% of head length............................................................................................... J. weberi (Hardenberg, 1936)

9a. Lower jaw with inner row of molariform teeth posteriorly............................. J. macrorhynus (Mohan, 1976)

9b. Lower jaw teeth all conical, uniform in size............................................................... 10

10a. Total outer gill rakers of 1 st arch 16–18................................................ J. carouna (Cuvier, 1830)

10b. Total outer gill rakers of 1 st arch 13–15................................................................... 11

11a. Gill rakers of outer gill rakers of 1 st arch at the upper limb, 4–5 (mode 4) and lower limb 9–11 (mode 10) respectively.................................................................................... J. heterolepis Bleeker, 1873

11b. Gill rakers of outer gill rakers of 1 st arch at the upper limb, 4–6 (mode 5) and lower limb 8–10 (mode 9) respectively..................................................................................... J. sasakii sp. nov. this study

Figures

FIGURE 1. (A) The distinctly enlarged teeth on upper and lower jaws from Johnius (Johnieops) borneensis, NMMB-P 15389 (147 mm SL) (front view). (B) The slightly enlarged teeth on upper jaw; small and uniform teeth on lower jaw from paratype of Johnius (Johnius) sasakii sp. nov., NMMB-P 34743 (143 mm SL) (front view).