Revision of Plesiops — INGER 
263 
Plesiops nigricans Riippell, 1835, Neue Wirbelt., 
Fische, p. 5; Gunther, 1861, Cat. Fishes 
Brit. Mus., 3: 363; Klunzinger, 1871, ZooL- 
Bot. Gesell. Wien, Abhandl. 21: 517. 
Compilations of the last 75 years (e.g., 
Bleeker, 1875; Boulenger, 1895; Jordan and 
Seale, 1906; Weber and de Beaufort, 1929) 
have described P. nigricans Riippell as a fish 
having a dark, light-rimmed opercular spot. 
However, RuppelFs figure (1828) of the type 
of nigricans does not show an opercular ocel- 
lus, nor is one mentioned in his description. 
Dr. Zilch has re-examined the type and an- 
other specimen collected by Riippell and 
states (personal communication) that neither 
has such a mark. 
Significantly, none of the above authors, 
with the exception of Riippell, had specimens 
from the Red Sea or Africa. Smith (1952) 
suggests correctly that true nigricans Riippell 
has never been found in the eastern Indian 
Ocean or in the Pacific. As far as I have been 
able to learn, only one specimen (USNM 
147530) of nigricans has been recovered since 
RiippelFs time. 
Gilchrist and Thompson (191 1), Barnard 
TABLE 2 
Number of Individuals of Three Species of Plesiops 
with Different Numbers of Branches in 
the Sixth Ray from the Ventral Edge 
of the Pectoral Fin 
STANDARD 
length 
SPECIES 
NUMBER OF 
BRANCHES 
2 
3 
4 
Under 40 mm. . . 
cephalotaenia 
4 
coeruleolineatus 
4 
oxycephalus 
1 
Subtotal 
8 
1 
40-49 mm. ..... 
cephalotaenia 
1 
2 
2 
coeruleolineatus 
9 
2 
oxycephalus 
3 
1 
Subtotal. ..... 
13 
4 
3 
50 mm. and up . 
cephalotaenia 
2 
coeruleolineatus 
1 
1 
oxycephalus 
2 
Subtotal. ..... 
1 
1 . 
4 
(1927), and Smith (1949, 1952) have assigned 
certain fishes from southeastern Africa to this 
species. Their specimens, however, differ 
markedly from nigricans , and are described 
in this paper as multisquamata . 
Diagnosis : Dorsal spines XII; lateral line 
19-23 + 14-17; scales in mid-lateral series 
23-27; scales in transverse series 3-4/1/8-9; 
total gill rakers on first arch 18-19; two 
lowest pectoral rays with at least four branches 
each in fishes over 45 mm.; lower pectoral 
rays free in distal halves; standard length up 
to 100 mm.; opercle without large ocellus; 
head and body often with minute blue or 
whitish spots; caudal fin black. 
Description: Dorsal XII, 7; pectoral 20-22; 
pelvic I, 4; anal III, 8; gill rakers 6+12; 
total length to 132 mm.; standard length to 
105 mm. 
Body oval or oblong, compressed; dorsal 
profile convex, rising in feebly curved line to 
dorsal origin; line .from snout to dorsal origin 
making a 30 degree angle with mid-lateral 
line; ventral profile convex, sloping in straight 
line from snout to insertion of pelvic; snout 
pointed in profile, shorter than eye; mouth 
oblique; maxilla reaching perpendicular from 
hind border of orbit; anterior nostril midway 
between tip of snout and eye, posterior just 
before orbit; diameter of orbit equal to great- 
est preopercular width, about twice inter- 
orbital. 
Origin of dorsal slightly in advance of 
pectoral base; spinous portion two or three 
times length of soft part; fin obtusely pointed 
posteriorly; spines gradually increasing in 
length posteriorly; first spine three-fifths 
length of second which equals eye diameter; 
last spine slightly less than post-orbital part 
of head; longest soft rays greater than distance 
between orbit and base of pectoral; membrane 
extending beyond tips of spines, incised along 
leading edges of spines; notch reaching three- 
fourths of distance to base of second and 
third spines; notch decreasing in depth there- 
after to last spine before which it reaches one- 
third distance to base. 
