Alebion echinatus Capart from Japanese Waters, 
with Observations on the Newly Found Male Form 1 
Sueo M. Shiino 2 
The hammerhead shark, Sphyrna zygaena 
(Linne) , was reported by Wilson (1932) as 
infected by a copepod belonging to the 
Family Euryphoridae, Alebion crassus Wilson, 
at Woods Hole. On the same shark caught 
off Hamazima, Mie Prefecture, Japan, I found 
another species of the same genus, A. echinatus 
Capart, which was recently discovered on S. 
diplana in the gulf of Senegal (Capart, 1953). 
This species was based on a single female and 
the male was unknown. As the original diag- 
nosis was rather brief and my collection in- 
cluded a male form, a new description has 
been prepared for both the sexes. 
Alebion echinatus Capart, 1953 
Capart, A., 1953. Inst. Frang. d’Afrique noire, 
Bui. 15: 655-656, Fig. 4. 
Two females and a male, found on the 
outside surface of Sphyrna zygaena (Linne) 
(new host), off Hamazima, Mie Prefecture, 
Japan. 
Female (Figs, la-j, 2 a-g): Thickly covered 
with minute dendritic patterns of dark red, 
the color appearing uniform over whole dorsal 
surface to the naked eye; ventral surface much 
paler. Eye pigment blackish. 11.4 mm. X 
10.4 mm. 
Carapace almost half as long as body, wider 
than long, orbicular, with depressed front 
and well-rounded sides. Central part con- 
siderably raised and rugose on the surface. 
Frontal plates about half the entire width, 
slightly arched and with blunt lateral ends. 
Transverse suture a little undulated and placed 
just behind the center of carapace. Longi- 
tudinal sutures slightly curved laterally both 
1 Contribution No. 23 from the Faculty of Fisheries, 
Prefectural University of Mie. 
2 Faculty of Fisheries, Prefectural University of Mie, 
Tsu-City, Japan. Manuscript received July 26, 1954. 
before and behind transverse one. Two 
grooves arising from anterior end of each, 
one narrow, short, extending antero-mesially, 
the other broader, horizontal, connected with 
lateral margin of carapace by a curved, diag- 
onal suture. Another pair of grooves extends 
from the bases of the frontal plates postero- 
mesially and intersects a short transverse one 
at anterior one fourth of cephalic area. Eyes 
at the center of this area. Thoracic area armed 
with short spinules close to its truncate pos- 
terior border on each side. Sinuses deep, 
obovate, with broad membranes along their 
lateral edges. Narrow areas just outside them 
are traversed by longitudinal folds raised 
above the surface and expanded at the caudal 
end into oval lobes which cover the posterior 
openings of the sinuses. Lateral areas relatively 
broad terminating in blunt lobes which pro- 
ject for some little distance beyond thoracic 
area. 
Fourth thoracic segment with a pair of oval 
dorsal plates covering anterior half of suc- 
ceeding segment; the plates separated from 
each other by a deep, narrow, median crevice. 
Width of the segment across the plates 3 / 7 
that of carapace, and the length inclusive of 
these 2 A the width. Genital segment large, 
about half as long as carapace on the midline, 
and same time as wide on an anterior level. 
It is convex dorsally, more or less quadrate, 
with antero-lateral angles slightly produced, 
and with posterior border emarginate. It is 
reinforced laterally near the caudal end by 
triangular lamellae and at the caudo-lateral 
angles by long lanceolate diagonal processes. 
Outer and caudal margins of the lamellae, 
inner margins of the processes, anterior por- 
tions of lateral margins and lateral portions of 
caudal margin fringed with a row of sharp 
spines. Caudal margin also with a pair of 
177 
