NO. 3567 LABIDOCERA JOLLAE GROUP—FLEMINGER 3 
male sex. Following description of the three species, ranges and 
interspecific relationships are discussed with special regard to their 
bearing on evolution within the group. 
The genus Labidocera was established by Lubbock (1853) for a 
new species, L. darwinia Lubbock, collected off Argentina at latitude 
38°5’ S. More than 40 species have subsequently been described. 
Although substantial revision of this complex is necessary, it must 
be delayed due to the lack of appropriate collections for study. In 
this report the genus Labidocera is used in the sense of Giesbrecht 
(1892) and refers to those pontellids with (1) one pair of dorsal sub- 
cuticular lenses in forehead; (2) rostrum deeply bifurcated and lacking 
a lense; (3) medioventral eye protuberant and extending antero- 
ventrad between rostral prongs; (4) first pair of swimming legs with 
two-segmented endopod; (5) male right antennule with at least four 
separate segments distal to hinge between segment 18 and fusion 
segment 19-21; (6) maxillule with basipod about twice the length 
of endite 2, maxilliped with six distinct segments. 
Roughly 20 percent of the species of Labidocera, including the jollae 
group, bear lateral head-hooks, which are obscure structures best 
seen in dorsal view. All are coastal in habitat. Most are restricted 
to the Indian and western Pacific Oceans although one is found in 
the northeast Atlantic and the jollae group occurs along the west 
coast of North America. Their phylogenetic relationships are not 
yet established; however, zoogeographically reasonable groups can 
be sorted out using segmentation of the antennule, sexually modified 
appendages, and female urosome segmentation. On this basis the 
jollae group can be regarded as being monophyletic and widely 
separated from the other head-hooked species. Extrapolating from 
‘present day ranges, no other head-hooked Labidocera has occupied 
any portion of the Western Hemisphere—at least since late 
| Pleistocene. 
_ This research was partially supported by National Science Founda- 
tion Grants G 19417 and GB 2861. A large number of plankton 
‘samples used in this study were obtained through the generous 
cooperation of colleagues with Scripps Institution of Oceanography, 
the Bureau of Commercial Fisheries, La Jolla Laboratory, and the 
Inter-American Tropical Tuna Commission. Especially notable 
contributions of coastal plankton were made by T. Matsui, S. Kato, 
R. H. Rosenblatt, F. H. Berry, B. Zahuranec, W. Klawe, and M. 
Gilmartin. I have been greatly helped with preparation of the manu- 
script by the thoughtful council of C. R. Stasek, who read an early 
draft, and by T. E. Bowman and several members of the curatorial 
staff of the U.S. National Museum, who read the final draft. 
