FISHERY BULLETIN: VOL. 7L NO. 2 



_-., 



1.00 

 .90 

 80 

 70 

 .60 

 .50 

 .40 

 .30 



 Group 1 

 _ O Group 2 

 D Group 3 



* 



* «o 



DO 



O 



D 



on 



D D 



K 



V 



I I I I 



16 



18 20 22 24 26 28 



30 32 34 36 38 40 42 44 46 48 50 52 



carapace length (mm) 



Figure 10. — Ratio of length of spine (C) on third pleonic tergum to distance between 

 transverse groove and posterior margin of tergum (D) plotted against carapace length in the 

 three groups (see text) of Hepomadus tener. 



The differences which earlier authors have 

 pointed out in the labrum, "epistome," among 

 Hepomadus, seem to be due to changes in the 

 relative position of its two lobes in preserved 

 specimens. The posteroventral lobe may be 

 only slightly raised and continuous with the 

 anterodorsal lobe, or the posteroventral lobe 

 may be thrust over the anterodorsal so that the 

 two lobes become distinctly delimited. 



Another character that has been cited as 

 supposedly useful in differentiating species of 

 Hepomadus in the western Atlantic is the shape 

 of the posteroventral teeth of the sixth pleonic 

 somite; however, it is variable, ranging from 

 broadly triangular to subspiniform, in all 

 three groups. 



In addition to the features which have been 

 studied by previous workers and discussed 

 above, I have found that the length of the third 

 pair of maxillipeds and five pairs of pereopods 

 shows individual variation, but no consistent 

 differences occur between the three groups; 

 furthermore, the appendix interna may fall 

 short or overreach the appendix masculina 

 within each group, and also the two cicatrices 

 on the sixth abdominal somite not only may 

 be widely separated or almost fused within each 



group, but also both extremes are found in 

 specimens of a single lot (e.g., 1 / 1 ■? taken 

 off Alabama, at Albatross stn 2379). 



The three groups of H. te)ier are not geo- 

 graphically isolated, but Groups 1 and 2 have 

 been found off the east coast of the United 

 States, the former ranging southward to the 

 Bahamas and the latter to the Sargasso Sea. 

 All three groups live in the Gulf of Mexico 

 and the Caribbean Sea. 



ACKNOWLEDGMENTS 



I am indebted to Willard D. Hartman (YPM), 

 Willis E. Pequegnat (TAMU), and Gilbert L. 

 Voss (UMML) for making material available; 

 also to Anthony L. Rice of the British Museum 

 (Natural History) for placing at my disposal 

 the holotype of Hepomadus glacial is Bate. 

 Grateful acknowledgment is extended to 

 Horton H. Hobbs, Jr., of the Smithsonian 

 Institution (SI); Bruce B. Collette of the 

 Systematics Laboratory, National Marine Fish- 

 eries Service, NOAA (NMFS), for invaluable 

 suggestions made during the preparation of 

 this work; and Thomas E. Bowman (SI) and 



452 



