30 
Fishery Bulletin 11 7(1-2) 
Table 4 
Proportional measurements of females (in % of total length) from 6 regional populations of Okamejei kenojei and their 
morphological differentiation significance among populations. Ranges are followed by mean ±standard deviation in paren¬ 
theses. Numbers under Significance indicate P values in ANCOVA. Populations separated by < are significantly different. 
NS=nonsignificant. Population abbreviations are given in Table 1. 
EC 
72 = 16 
YS 
72=4 
SJ 
72=36 
EK 
n -5 
OS 
72 = 17 
NP 
72=39 
Significance 
Total length (mm) 
104-410 
415-430 
103-457 
153-471 
341-503 
108-536 
(275 ±97) 
(422 ±6) 
(362 ±83) 
(354 ±113) 
(411 ±35) 
(398 ±125) 
Disc length 
55.3-59.0 
55.7-60.8 
54.4-61.2 
57.1-61.7 
56.5-61.1 
54.3-64.5 
0.001 [EC, SJ<OS, NP] 
(57.4 ±1.1) 
(57.9 ±2.0) 
(57.8 ±1.8) 
(59.6 ±1.4) 
(59.4 ±1.2) 
(59.2 ±1.8) 
Disc width 
67.8-72.2 
67.5-72.7 
64.5-73.7 
66.7-74.4 
67.2-73.0 
65.3-78.1 
< 0.001 [EC, SJ. OS<NP] 
(69.8 ±1.5) 
(70.5 ±2.1) 
(69.4 ±2.4) 
(70.9 ±2.7) 
(69.6 ±1.7) 
(71.8 ±2.4) 
Tail length 
45.4-52.1 
42.5-47.4 
42.0-51.1 
43.2-49.9 
41.1-46.4 
42.9-52.5 
< 0.001 [SJ, OS, NP<EC] 
(48.7 ±1.7) 
(45.8 ±1.9) 
(45.8 ±2.3) 
(45.4 ±2.4) 
(44.3 ±1.1) 
(45.8 ±2.3) 
Dorsal head length 
20.6-24.1 
19.3-22.7 
19.8-23.9 
22.9-24.0 
22.0-24.0 
19.8-23.7 
< 0.001 [EC, EK, OS<NP] 
(22.6 ±0.9) 
(20.5 ±1.3) 
(21.9 ±0.9) 
(23.4 ±0.4) 
(23.0 ±0.7) 
(21.4 ±0.9) 
[EK. OS<SJ] 
Dorsal snout length 
14.3-17.6 
14.1-16.2 
13.4-16.8 
16.1-17.3 
16.0-17.7 
13.8-16.9 
< 0.001 [EC, SJ, NP<OS] 
(15.9 ±0.8) 
(14.7 ±0.9) 
(15.3 ±0.9) 
(16.6 ±0.4) 
(16.7 ±0.6) 
(15.1 ±0.7) 
[EC, EK<NP] [SJ<EK] 
Eye diameter 
3.0-3.8 
2.8-3.0 
3.0-4.3 
3.2-3.9 
2.6-3.3 
2.7-4.1 
< 0.001 [EC, SJ, NP<YS, OS] 
(3.4 ±0.3) 
(2.9 ±0.1) 
(3.6 ±0.3) 
(3.5 ±0.2) 
(3.0 ±0.2) 
(3.3 ±0.3) 
[SJ<NP] [EK<OS] 
Distance between orbits 
3.8-5.1 
4.8-5.5 
4.5-5.7 
4.5-5.4 
4.9-5.8 
4.6-6.2 
NS 
(4.7 ±0.3) 
(5.2 ±0.3) 
(5.0 ±0.3) 
(5.0±0.3) 
(5.4 ±0.2) 
(5.5 ±0.4) 
Ventral head length 
27.2-31.4 
27.9-32.2 
27.3-32.0 
30.2-31.4 
29.6-32.1 
26.7-31.7 
0.001 [SJ, NP<OS] 
(29.8 ±1.1) 
(29.2 ±1.8) 
(29.8 ±1.0) 
(30.8 ±0.4) 
(30.7 ±0.7) 
(29.5 ±1.1) 
Ventral snout length 
14.5-18.2 
14.0-16.6 
13.6-17.7 
16.7-18.8 
15.8-17.7 
13.9-17.5 
0.001 [SJ, NP<OS] 
(16.6 ±0.9) 
(14.9 ±1.0) 
(15.9 ±0.9) 
(17.4 ±0.8) 
(16.8 ±0.5) 
(15.4 ±0.8) 
Prenasal snout length 
11.7-14.5 
11.1-13.3 
10.9-13.8 
13.1-14.7 
12.9-14.7 
11.4-14.5 
<0.001 [YS, SJ, NP<OS] 
(13.2 ±0.7) 
(11.8 ±0.9) 
(12.6 ±0.7) 
(13.7 ±0.6) 
(13.7 ±0.5) 
(12.4 ±0.7) 
[EC, EK<NP] [SJ<EK] 
Distance between nostrils 
7.6-8.4 
7.8-8.5 
7.5-8.9 
8.0-8.4 
8.0-9.0 
8.0-9.6 
< 0.001 [EC, YS, SJ, EK, OS<NP] 
(8.0 ±0.3) 
(8.1 ±0.3) 
(8.3 ±0.3) 
(8.2 ±0.1) 
(8.4 ±0.3) 
(8.8 ±0.3) 
[EC<OS] 
Distance between 
14.8-16.5 
14.7-15.9 
14.8-18.0 
15.2-16.2 
14.9-16.1 
15.2-18.5 
< 0.001 [EC, YS, SJ, EK, OS<NP] 
1st gill openings 
(15.6 ±0.5) 
(15.5 ±0.4) 
(16.1 ±0.7) 
(15.6 ±0.4) 
(15.5 ±0.3) 
(16.7 ±0.6) 
[SJ<OS] 
brown or chocolate brown with a pair of pale ocelli and 
several small paler spots, these markings sometimes 
indistinct (Fig. 7A); SJ—dorsal surface dark, light, or 
yellowish brown with 2 pairs of pale or whitish ocel¬ 
li, and several paler or yellowish spots (Fig. 7B); OS 
—dorsal surface dark brown or chocolate brown with 
a pair of pale ocelli and several lighter spots, these 
markings somewhat indistinct (Fig. 70; NP—dorsal 
surface dark brown or grayish brown with 2 pairs of 
light brown and whitish ocelli, and numerous small 
black specks and several irregular whitish and yellow¬ 
ish spots, and pairs of whitish spots close together on 
dorsal tail (Fig. 7D). 
Discussion 
Population structure of ocellate spot skate 
Both nucleotide and haplotype variation seen in mtCR 
sequences occurred at lower levels in the 5 populations 
of O. kenojei (Table 1), than those seen in other de¬ 
mersal bony fishes (Heyden et al., 2010). Low levels 
of genetic diversity have been frequently reported in 
other elasmobranchs (e.g. Hoelzel et al., 2006; Cannas 
et al., 2010; Daly-Engel at al., 2010; Verissimo et al., 
2010; Vargas-Caro et al., 2017), because they exhibit 
slower rates of genetic evolution than other vertebrates 
(Martin et al., 1992; Martin, 1999). In addition, Feutry 
et al. (2014) suggested that mtCR in elasmobranchs 
could be under higher evolutionary constraints than 
those of other mitochondrial regions. In the present 
study, however, the significant Fg T indices among the 
regional populations revealed a fine-scale population 
structure within O. kenojei, clearly indicating the lim¬ 
its of gene flow (Table 2). In fact, 11 of a total of 14 
haplotypes were unique to each regional population 
(Fig. 2, Ok4-14), and the frequency of private haplo¬ 
types was high, which accounted for 45% of all obser¬ 
vations. The results of the morphological comparisons, 
including measurements (Tables 3 and 4; Fig. 3), nu¬ 
chal thorn counts (Fig. 4), sizes at maturity in males 
and females (Figs. 5 and 6), and coloration (Fig. 7) also 
almost corresponded with the results from the mtCR 
