Parasitic Copepods of Mackerel - and Tuna-like Fishes (Scombridae ...

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along distal half, spines with bristled margins and
terminal flagellum, outer edges of endopod segments
haired. Leg 5 (Figure 186) basal segment with small
outer patch of short hairs and dorsal seta; free segment
with dense patches of hairs, one naked spine
with terminal flagellum on mid-outer margin, one
naked terminal seta flanked by 2 spines, outer spine
naked with terminal flagellum, inner spine with short
bristles along margins and terminal flagellum. Leg 6
(see Figure 17a) represented by 3 setae on genital
segment.
MALE.—Body form as in Figure 18c. Total length
1.36 mm, greatest width 0.52 mm; length of cephalon
0.35 mm. Genital segment longer than wide (336 X
289 /*m). Abdomen 2-segmented, segments measuring
(length X width) 100 X 129 /an and 70 X 106 (an
respectively; second segment (see Figure \8d) ornamented
ventrally with anterior, irregular row of minute
hairs and distally with 2 patches of minute hairs.
Caudal rami (Figure I8d) longer than wide (70 X
41 /an); each ramus with ventral patch of hairs and
6 setae; longest seta 383 /xm.
Cephalic appendages similar to those of U. collateralis
male.
Legs 1-4 biramous. Leg 1 (Figure \8e) coxopod
with broad inner seta and 2 short rows of fine spinules,
one on outer distal corner, one on mid-distal
edge; basipod with outer seta, blunt process near
insertion of rami, and inner spine sclerotized at base
and with fringed membrane distally, a large, prominent
patch of rounded spinules surrounding base of
spine and extending to mid portion of segment (see
Figure 18/); exopod first segment with stout spine on
outer distal corner, row of fine spinules surrounding
base of spine, second segment incompletely divided
with 6 inner to terminal setae, one outer setiform
spine and 2 stout outer spines (one dorsal) as indicated
in Figure 18/; endopod 3-segmented, similar to
U. collateralis except first 2 segments each with large
patch of hairs on distal half, and third segment with
spinules more prominent than those of U. collateralis
near bases of setae. Leg 2 (Figure 19a) coxopod with
inner plumose seta and row of hairs on mid-distal
margin; basipod with naked seta on outer dorsal
corner; exopod similar to that of U. collateralis except
first segment with large patch of fine hairs
around outer ventro-lateral portion of segment, also,
spinules at base of proximal 4 spines of ramus stout,
some almost half as long as accompanying spines;
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY
endopod similar to that of U. collateralis except first
and second segments each with large patch of fine hairs
along outer and distal borders, third segment with
comparatively small patch of fine hairs along outer
edge, and several short, irregular rows of minute spinules
as well as 2 or 3 small patches of bumps along
distal margin at bases of terminal 2 spines and 3 setae.
Leg 3 (Figure 19b) similar to leg 2 with following
exceptions: exopod first segment with 2 patches of
ventro-lateral spinules, proximal patch hairlike, distal
patch small, fine spinules; second segment lacks outer
spine and accompanying basal spinules; endopod third
segment with only 2 inner to terminal setae, outer
spines slightly larger than those of leg 2, with inner
spine about one-third longer than outer. Leg 4 (Figure
19c) coxopod, basipod, exopod similar to leg 3 except
ventro-lateral spinules of first segment all very fine
and third segment with only 4 inner to terminal setae;
endopod completely or incompletely divided into 3
segments (see "Remarks"), first and second segments
similar to those of legs 2 and 3 except second segment
lacks inner seta, third segment with 2 or 3 short,
irregular rows of fine spinules distally and 2 spines
flanking terminal seta, spines of about equal length,
each finely serrate and with terminal flagellum, seta
finely spinulose along distal two-thirds. Leg 5 similar
to that of U. collateralis, outer seta extending to about
half the length of genital segment.
REMARKS.—Vervoort (1965) first described this
species as Parabomolochus mycterobius. His description
was based on a single collection of 6 females and
2 males from the nasal sinus of Auxis thazard from
the Gulf of Guinea. Our collections have enabled us
to add details to Vervoort's original description.
Unicolax mycterobius females are the only known
members of the genus in which all the exopod spines
of legs 2-4 are edged with fine hairs; the distalmost
spine has fine hairs on the outer edge only, all other
exopod spines have hairs on both edges. Females of
other species of the genus have stout serrations on
some or all of the exopod spines of legs 2-A. The free
segment of leg 5 of U. mycterobius females has 3
patches of fine hairs; other species have patches of
distinctly stout spinules on the corresponding segment.
Males of the species can be separated principally
by the nature of legs 1 and 4. Leg 1 basipod has a
very large, prominent patch of rounded spinules near
the inner distal corner. Although males of other species
have ornamentation at the corresponding site, in