NO. 3656 COPEPODS—LEWIS 49 
to that of female although larger and first segment bearing 3 knoblike 
projections adjacent to ridge described for female. Sternal furca 
(fig. 20g) U-shaped, associated with trilobate platelike structure 
posterior to maxilliped bases; tines of furca sharply rounded distally. 
For nature and armature of thoracic legs I-IV, see figures 21la—f 
and table 8. Second segment of exopodite of first thoracic leg with 
only single plumose setule on inner surface. Pair of padlike structures 
present posterior to interpodal plate of first thoracic leg. 
Discusston.—Pseudocaligus similis most closely resembles P. 
fistulariae Pillai (1961) and P. tenwicauda Shiino (1964), both of which 
are also found on Fistularia. The similarities are not only in the overall 
body shape (especially the elongate, 2-segmented abdomen in the 
female and the shorter 2-segmented abdomen in the male) but also in 
TABLE 8.—Armature of thoracic legs I-IV of the female and male of Pseudocaligus 
similis, new species 
Inter- Protopodite Exopodite Endopodite 
Leg} Sur- podal so 
face plate 
1 2 1 2 3 1 2 3 
I | Outer p p’ 20H Hee! 
Inner p c p 
II | Outer m,p m,mH mH rh,H,Q ¢,c c ¢,3P 
m 
Inner ss,P m,s He c¢,P c,5P P c,2P c,3P 
III | Outer T,m,p m,mH ¢,p’ ¢,3p’ c c,2P 
m 
Inner* ss,P,s,m,s ¢;2 ¢c,P c,4P 12 c,4P 
IV | Outer# 3p 
*Elements in middle of protopodite not tabulated. 
#Elements not to be definitively associated with protopodite, status of segments obscure. 
the appendages, especially the male antenna. The fifth leg of both 
P. tenuicauda and P. similis is, however, 1-segmented while that of 
P. fistulariae is distinctly 2-segmented and has a plumose setule on 
the distal surface of the first segment. Pseudocaligus similis can be 
most readily distinguished from P. tenwicauda by 3 characteristics: 
1. The maxillule is better developed in P. similis and, in this respect, 
resembles the condition figured for P. fistulariae. 
2. The 3 terminal spines on the second segment of the exopodite of 
the first thoracic leg are described as being bifid in P. tenuicauda while 
only the inner 2 spines are bifid in P. similis although the armature of 
the spine can give a pseudobifid appearance in unstained specimens. 
3. The size of the terminal seta on the second segment of the 
exopodite of the first thoracic leg differs between the 2 species, being 
large in P. tenwicauda and small in P. similis. 
283-932—68——4 
