Frable et al: A new species of Sebastes 
363 
18 - 
16 - 
14 ' 
12 - 
10 
8- 
6 
4 
2l 
0- 
-20 
-15 
-10 
15 
B 
_ 
II 
-24 
-16 -8 0 8 
Discriminant 
16 
24 
Figure 5 
Results of a discriminant function from analysis of 32 linear mea- 
surements (A) for all specimens of Sebastes mystinus (blue rockfish) 
and S. diaconus (deacon rockfish) combined (n = 120), showing 98.3% 
discrimination, and (B) only specimens over 150 mm SL (S. mystinus, 
n= 37, and S. diaconus, n= 36), showing 100% discrimination. Black 
bars represent Sebastes mystinus, and light gray bars represent S. 
diaconus. 
Additional nontype material 
CAS 18799, 1, 128 mm SL, Off Santa Cruz Island, CA, 
29 August 1954, E. Hunter; CAS 25976, 1, 104 mm SL, 
Southeast Farallon Island, CA, 8 May 1949, G. D. Hanna 
and A. G. Smith; CAS 27910, 2, 67-93 mm SL, Arena 
Cove, Mendocino, CA, 38°54'51"N, 123°42'55"W, 8.5-9. 1 
m depth, 8 April 1973, R. N. Lea et ah; CAS 28487, 1, 
65 mm SL, Arena Cove, Mendocino, CA, 8 April 1973, R. 
N. Lea et ah; SU 11776, 1, 228 mm SL, Monterey, CA, 
December 1895, D. S. Jordan; SU 15112, 3, 63-117 mm 
SL, Pacific Grove, pier at far end of city beach, CA, 3 
August 1948, C. Limbaugh, A. Flechzig, and E. Walker; 
LACM 31938.002, 6 of 27, 52-120 mm SL, St. Georges 
Reef, Whale Rock, Del Norte, CA, 10.7-13.7 m depth, 2 
August 1971, D. Gotshall, D. Odenweiler, C. Swift, and 
D. Clifton; OS 1252, 2, 130-140 mm SL, beyond Yaquina 
Bay Bridge, OR, 27 May 1962, H. Murray; OS 4162, 1, 
250 mm SL, Pacific Ocean off mouth of Columbia River, 
OR, 9 May 1961, P. Wolf; OS 7466, 107 mm 
SL, Pacific Ocean off Tillamook County, OR, 
45°15.7'N, 124°0.6'W, 36.6 m depth, RV Cay- 
use, cruise C-7805-D, station 8, haul SBMT 
224, 16 May 1978, E. E. Krygier; OS 11176, 
1, 48 mm SL, off Oregon, 43°37'N, 124°15'W, 
36.6 m depth, 28 June 1978, collector un- 
known; UW 1559, 1, 168 mm SL, Farallon 
Islands, CA, 26 October 1922, C. L. Hubbs; 
UW 40703, 3 of 6, 71-111 mm SL, Monterey 
Bay, CA, 7 October 1953, W. I. Follett. 
Diagnosis 
A species of Sebastes differentiated from 
all congeners, except S. ciliatus, S. mela- 
nops, and S. mystinus, by possession of 
dark gray, blue, brown, or black body color- 
ation, scales that cover the mandible, and 
weak or absent head spination. Sebastes 
diaconus can be distinguished from S. cili- 
atus and S. melanops by the maxilla not 
extending beyond the posterior margin of 
the pupil when the mouth is closed. It is 
further distinguished from S. ciliatus by 
4 bars of dark pigmentation that extend 
across the head and nape, versus the al- 
most uniformly dark head coloration with 
2 faint bars below the orbit in S. ciliatus, 
and by 26-27 vertebrae versus 28-29 ver- 
tebrae in S. ciliatus. Sebastes diaconus is 
further distinguished from S. melanops by 
having a uniform, light blue-gray, speckled 
pattern on the trunk, versus the darker 
black-gray coloration with irregular areas 
of dark pigmentation ranging from speck- 
ling to blotches in S. melanops, and by 
having dark dorsal-fin membranes with- 
out dark spots. Sebastes diaconus is most 
easily distinguished from S. mystinus by a 
brownish-blue to blue-gray trunk with dis- 
tinct lighter blue-gray speckles versus the steel-blue to 
greenish-blue body coloration and large, dark blotches 
(also apparent in preserved specimens) of S. mystinus ; 
this character is indistinct in many individuals under 
100 mm SL. In specimens over 150 mm SL, S. diaconus 
can be further distinguished from S. mystinus by hav- 
ing the ventral margin of head and ventrum generally 
flat versus rounded and by the allometric development 
of the symphyseal knob (length of dentary symphysis 
4. 0-7.0% HL vs. 2. 6-5. 7% HL in S. mystinus). Although 
these ratios overlap, the symphyseal knob length dif- 
fers diagnostically among specimens of equal size over 
150 mm SL. This measurement can be diagnosed by 
comparison with allometric plots (Fig. 6A). 
Description 
Description based on 58 specimens, 48.2-344.0 mm SL. 
Counts and measurements of holotype and ranges, av- 
