Lucifuga Poey

Peter R. Møller, Werner Schwarzhans, Thomas M. Iliffe & Jørgen G. Nielsen, 2006, Revision of the Bahamian cave-fishes of the genus Lucifuga (Ophidiiformes, Bythitidae), with description of a new species from islands on the Little Bahama Bank., Zootaxa 1223, pp. 23-46 : 43-44

[[ Genus Lucifuga Poey ]]

Discussion

With the data presented above, it has become obvious that the diversity of Bahamian Lucifuga is larger than hitherto assumed, i.e., that at least two species ( L. lucayana and L. spelaeotes ) are present. The Bahamian species seem to be closely related, differing from the four Cuban species by having more caudal finrays (10 vs. 8), larger eyes (0.7-1.8 vs. 0.0-0.3 % SL), more vertebrae (50-55 vs. 45-48) (not known for L. teresinarum ) and more pectoral finrays (17-20 vs. 10-17) (Table 3). The new Bahamian species supports and extends the results of Vergara (1980), who hypothesized that the Bahamas and Cuba are inhabited by two lineages of Lucifuga evolution, with the Bahamian species being more plesiomorphic in the above mentioned characters. Based on this hypothesis, the reduction of palatine dentition and head squamation must have occurred independently in both lineages (see Romaro 2001).

Given the homoplasious nature of this character, the presence or absence of palatine teeth is not useful for supporting generic (Gill 1863) or subgeneric (Cohen & Robins 1970) ranking in Lucifuga . It is, however, a useful character in defining the cave-dwelling bythitid genus, Grammonus Gill (Nielsen et al. 1999) and in the separation of Lucifuga species, although the number of teeth are here shown to be rather variable and to increase with increased specimen size in L. spelaeotes (fig. 6).

Another controversial character is the degree of eye-reduction. Cohen and McCosker (1998) and Nielsen et al. (1999) argued that the degree of eye development is not a good taxonomic character and should be avoided in keys for Lucifuga , because it has been reported to vary and to be less well developed in older specimens of L. dentata and L. subterranea (Eigenmann 1909, Wilkens et al. 1989). Great variability and a tendency to negative allometric growth is here shown for L. spelaeotes as well (fig. 5), but this does not mean that the size of the eye-ball cannot be used in Lucifuga taxonomy. It is useful for separating Bahamian from Cuban Lucifuga spp. and in the systematics of many other bythitid fishes, of course with due consideration of allometric change.

We agree with Nielsen et al. (1999) that the amount of pigmentation is not a good taxonomic character in Lucifuga , since it varies considerably even among fish from the same cave (fig. 7A -B).

The distribution pattern of Lucifuga in the Bahamas shows endemic species from the Little Bahama Bank area and the Grand Bahama Bank area, separated by the Northeast (3800 to 4700 m deep) and Northwest (700 to 2800 m deep) Providence Channels (fig. 1). A similar distribution pattern has been reported for other anchialine cave animals as well. Among the 13 stygobitic species of the crustacean class Remipedia known from the Bahamas archipelago, five are recognized from Grand Bahama Island and the same five also inhabit Abaco Island. Although one remipede, Speleonectes lucayensis , occurs on both the Great Bahama Bank (Andros and Cat) and the Little Bahama Bank (Grand Bahama and Abaco), the remaining species are known from a single platform, Great Bahama Bank (Great Exuma), San Salvador Bank and Caicos Bank (Koenemann et al. 2003; 2004).

Thus, Lucifuga seems at least to some extent to show a similar pattern of endemism as some of its potential food items.

It is possible that the deep Northeast and Northwest Providence Channels form a barrier for most marine shallow-water bythitid fishes as well. Six species ( Ogilbia boehlkei Moller et al., 2005 ; Ogilbia sabaji Moller et al., 2005 ; Ogilbia suarezae Moller et al., 2005 ; Ogilbichthys kakuki Moller et al., 2004b ; Ogilbichthys longimanus Moller et al., 2004b and Stygnobrotula latebricola Boehlke, 1957 ) are found only south of the Channels, whereas only one species ( Calamopteryx goslinei Boehlke & Cohen, 1966 occurs both to the north and south of the deep Channels.

Conservation. Lucifuga spelaeotes is on the Red List of threatened species of International Union for Conservation of Nature and Natural Resources (IUCN), 2003. It is listed as vulnerable (VU (A1ce, B1+2bc, D2)), based on decline in area, quality of habitat and pollution. For instance, it has not been observed in recent years in the type-locality, Mermaid ’s Pool (Proudlove 2001). The D2 criterion requires an estimated population size of less than 1000, or that the area of occupancy is less than 100 km2, or that the number of recorded locations is fewer than 5. Proudlove (2001) suggested a lower degree of protection(least concern, LC), based on the reported wide distribution in relatively unspoiled nature, and well separated from the polluted type locality. Because of the present separation of the new species, L. spelaeotes is now known from six locations (islands) of which only 5 could be confirmed by examination of specimens. We therefore strongly recommend that the D2 status is maintained until we have a more detailed picture of the diversity and distribution of the Bahamian species and populations. Since L. lucayana is known from very few specimens, and fewer than five localities, it is obvious that it should be given at least the same rank of protection as L. spelaeotes .