Lucifer chacei n. sp. — Bowman 
269 
Fig. 3. a—c, Lucifer chacei : a, petasma in situ, medial; b, petasma sheath with its processus ventralis, and 
proximal lobe at base of sheath ; c, petasma sheath of another male, with processus ventralis displaced. 
d-e, Lucifer faxoni : d, petasma in situ, medial; e, petasma sheath with processus ventralis displaced. 
diagnosis: A Pacific species belonging to 
Hansen’s (1919) "Group B” (species with short 
eyestalks), closely resembling the western At- 
lantic L. faxoni in having the apex of the 
petasma acute, without transverse lines or pro- 
truding plates or scabrousness, and in having a 
slender processus ventralis with acute apex. 
The diagnostic features of L. chacei in com- 
parison with L. faxoni are shown in Table 1. 
The new species is named for my colleague, 
Fenner A. Chace, Jr., in recognition of his many 
contributions to decapod crustacean taxonomy. 
remarks: Of the remaining species of Luci- 
fer , only L. hanseni Nobili agrees with L. 
faxoni and L. chacei in having a slender, acutely 
ending processus ventralis. However, L. hanseni 
can be identified immediately by the uniquely 
shaped uropodal exopod, in which the outer 
tooth is located considerably proximad of the 
distal margin. 
Previous workers reporting L. faxoni from 
the Pacific naturally based their identifications 
on Hansen’s (1919) monograph. None had 
reason to suspect that Hansen’s description and 
illustrations dealt with an undescribed species. 
Although Hansen stated that the Copenhagen 
Museum possessed several samples of Atlantic 
L. faxoni, he could not have compared them 
carefully with his Siboga material. I cannot be- 
lieve that the distinguished Danish carcinologist 
would have overlooked the differences separat- 
ing the two species. 
L. chacei is so similar to L. faxoni that it is 
possible that their genetic divergence is at the 
subspecific rather than the specific level. They 
probably have been derived from a common 
ancestor. The actual level of divergence from 
this ancestor cannot be ascertained from avail- 
able collections, and, since the two forms are 
completely isolated from one another, there is 
no possibility of gene flow between them at 
present. If plans for a sea level canal connecting 
the Caribbean Sea and the Pacific Ocean are 
carried out, the picture may change drastically. 
