Lucifuga spelaeotes Cohen & Robins, 1970

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 : 34-41

Lucifuga spelaeotes Cohen & Robins, 1970

(Figs. 4-9, Tables 1-3)

Lucifuga spelaeotes Cohen & Robins, 1970 : 133, fig. 1; Barton & Wilmhoff 1996: 9; Cohen & McCosker 1998: 184 (part); J. Yager (part) in lift. in Cohen & McCosker 1998: 185; Nielsen et al. 1999: 122 (part); Proudlove 2001: 207 (part); Romero & Paulson 2001: 32.

Material examined (44 specimens, 42-166 mm SL).

Holotype: USNM 204603 , 110 mm SL, male, Bahamas, New Providence, Mermaid’s Pool , 25°01'N, 77°22'W, 0-5 m depth, collected by C. Ray, 24 Oct. 1967.

Paratype: USNM 204604 , 75 mm SL, female, same data as for holotype .

Additional specimens: AMNH 53011 (5 specimens), 94-132 mm SL, New Providence, Ocean Blue Hole (precise location and collection data unknown) ; AMNH 53012 (4 specimens), 103-113 mm SL, New Providence, ocean blue hole (precise location and collection data unknown) ; AMNH 53011 (5 specimens), 101-124 mm SL, New Providence, ocean blue hole (precise location and collection data unknown) ; AMNH 57448 , 96 mm SL, male, Bahamas, southern Long Island, Hard Bargain, Alphonso Dean’s Blue Hole , most likely at 23°1.071'N, 74°54.085'W, depth unknown, collected by Dennis Williams, 2 August 1985 ; ANSP 147575 , sex unknown, 121 mm SL, New Providence Island, southwestern side of island, sinkhole adjacent to 15th hole, South Ocean Golf Club , 25°00'N, 77°32'W, depth 0-0.5 m, collected by J.E. and M.W. Böhlke with hand net, 21 Aug. 1972 ; ANSP 148055 , sex unknown, 138.5 mm SL, New Providence, small ocean hole northwest of Robertson Road east-west highway junction , 25°02'N, 77°20'W, 3-4 m depth, collected by J.E. Böhlke with hand net, 24 Aug. 1972 ; ANSP 148058 (8 specimens), 42-134 mm SL, same data as for ANSP 148055 ; ANSP 148059 (10 specimens), 88-123 mm SL, New Providence, south-western side of island, sinkhole adjacent to 15th hole, South Ocean Golf Club , 25°00'N, 77°32'W, 3 m depth, 31 Oct. 1973 ; UMMZ 213989 , 148 mm SL, male, Berry Islands, Holmes Key, Blue Hole , 25°37'N, 77°44'25''W, depth unknown, collected by D.L. Schultz, 25 February 1982 ; USNM 274737 , 109 mm SL, male, Bahamas, southern Long Island, Twin Pillars Cave System, Miley , 23°3.841'N, 74°55.503'W, depth 0-2 m, collected by Dennis Williams, 29 July 1985 ; ZMUC P771363 , 90 mm SL, female, Stocking Island, near Great Exuma, Angelfish Blue Hole , approximately 23°31.5'N, 75°45.6'W, collected by hand net, about 57 m inside the cave, at depth of 28 m, by B. Kakuk and T. Iliffe, 1 March 2003 ; ZMUC P771365 , 132 mm SL, male, Eleuthera Island, Nixon's Blue Hole , approximately 24°05'N, 76°00'W, collected at the cave entrance by hand net, at depth of 12 m, by B. Kakuk, 24 Feb. 2003 ; ZMUC P771452 , 136 mm SL, female, central Long Island, Silent Hole, (circular blue hole 30 m diameter with an undercut lip and a 3 m drop to water level) in Gray’s settlement , 23°13.361'N, 75°05.862'W, maximum water depth 15 m, with a halocline and associated hydrogen sulfide layer at 8 m, collected with dip net by T. Iliffe and collaborators, 8 January 2005 ; ZMUC P771453 , 166 mm SL (182 mm TL before preservation), male, central Long Island, Grotto, behind the ruins of the old Spanish Church in Pratts Hill settlement , 23°16.590'N, 75°5.995'W, depth 2.5 m, temperature24°C, pH 7.33 and dissolved oxygen 5.5 mg/l, collected with a dip net by T. Iliffe and collaborators, 7 January 2005 ; ZMUC P771454 , 155 mm SL, female, central Long Island, Grotto , 23°16.590'N, 75°5.995'W, collected with a dip net by T. Iliffe and collaborators, 12 January 2005 .

Diagnosis. Lucifuga spelaeotes is distinguished from other members of the genus by the following combination of characters: Vertebrae 13-14+38-42=51-55, dorsal finrays 86-109, anal finrays 66-82, pectoral finrays 17-20, caudal finrays 10; head profile above eye strongly depressed, eyes 0.7-1.8 % SL; palatine teeth present, in 1-7 short irregular rows, with 3-56 teeth totally; long gill-rakers 3, dark pigmented.

Similarity. Lucifuga spelaeotes is most similar to L. lucayana (Tables 1-3). It differs mainly in the reduced squamation on the occiput (vs. densely scaled in L. lucayana ) (fig. 4), the presence of palatine teeth, except absent in one side of a single specimen, USNM 274737 (vs. absent in L. lucayana ) (fig. 6), and in having dark pigmentation on the three elongated gill-rakers, except absent in 3 specimens: AMNH 57448, USNM 274737 and ZMUC P771363 (vs. pale in L. lucayana ). Also, the number of finrays and vertebrae tend to be higher in L. spelaeotes than in L. lucayana (Tables 1-3).

Differences to the four Cuban species are shown in Table 3. Lucifuga spelaeotes resemble the Cuban species L. dentata and L. simile in the presence of palatine teeth, but the teeth bearing area of the palatine is broader, shorter and with more teeth rows in L. spelaeotes than in L. dentata and L. simile (see Nalbant 1981), when comparing specimens of similar sizes.

Description. Meristic and morphometric characters are given in Tables 1-3. Body moderately elongate, compressed. Head profile strongly depressed (figs. 4, 7-9). Eyes usually relatively large (> 1 % SL), except for a few specimens (AMNH 53011, 132 mm SL, New Providence; AMNH 53013, 101 and 103 mm SL, New Providence; AMNH 57448, 96 mm SL, Long Island (fig. 4E -F); USNM 274737, 109 mm SL, Long Island and ZMUC P771452, 136 mm SL, Long Island) with eyes from 0.7 to 1.0 % SL (fig. 5). Upper jaw slightly protruding. Anterior nostril tube-shaped, low on snout near upper lip; posterior nostril larger, a mere hole, closer to lip than to eye. Maxilla expanded posteriorly, not sheathed by a skin flap. Opercular spines absent. Anterior gill arch with 3 elongated rakers and 17 (12-20) broad plates arranged in the following configuration: upper branch of anterior gill arch with 4 (2-5) broad plates, the bend between upper and lower arch with 1 elongate raker and lower branch with 1 small plate, 2 elongate rakers interspersed with 1 small plate and followed by 12 (7-12) small plates. Pseudobranchial filaments 0 (0-4). Branchiostegal rays 7.

Scales on body relatively small, oval (horizontal diameter about 1.3 mm at mid-body and about 25 horizontal rows above anal fin origin in a 132 mm SL male); vertical fins and pectoral fins naked except for scales on pectoral fin peduncle. Predorsal area, operculum and top of head, including a narrow central part of the occiput scaled. Interorbital, snout and at the course of the head pore channels, including the lateral parts of the occipital area naked (figs. 4C -F, 8A -B).

Origin of dorsal fin above tip of pectoral fins. Pelvic fins with a single ray reaching about 1/2 (1/3-1/2) from its base to anal fin origin. Pectoral fins on the middle of body, peduncle short and narrow. Caudal fin free, not fused with dorsal or anal fins.

Head sensory pores: Supraorbital pores 4, anteriormost 3 on snout and posteriormost above opercular flap; infraorbital pores 6 (3 large anteriorly and smaller 3 posteriorly); mandibular pores 6 (3 anterior and 3 posterior), the 2nd anterior very long, the posterior ones increasing in size; preopercular pores 2 (2 lower and 0 upper) (fig. 8A -B). Lateral line with 14 (12-19) dorsal neuromasts anteriorly and 38 (30-47) medio-lateral neuromasts posteriorly. Many small sensory papillae on head.

Dentition: Premaxilla with 7 (3-9) rows of granular teeth and 1 inner row of small pointed teeth. Vomer horseshoe-shaped, with 2-6 rows and a total of 6-114 teeth, larger in inner row. Palatines with 5 (1-7) rows and 3-56 teeth totally, except for absent on one side in one specimen (USNM 274737). The number increasing with the size of the fish (fig. 6). Dentary with 3-14 outer rows of granular teeth and an inner row of longer pointed teeth.

First neural spine less than half the length of second spine; spine 2-4 longer and more slender than spines 5-9; spines 4-9 slightly depressed. Parapophyses present from vertebra8-13, increasing in length. Pleural and epipleural ribs on vertebrae 2-12. Last precaudal vertebra without ribs.

Male copulatory organ completely integrated in the fleshy genital hood (fig. 8C -D; Cohen & Robins 1970), similar to the configuration in L. lucayana .

Otolith thin, elongate to very elongate (length to height ratio 2.2 to 2.7), with rounded (fig. 8E -F) or pointed (fig. 8H) anterior tip. Posterior tips pointed. Postdorsal and to a lesser degree also postventral region irregularly concave. Sulcus very short, with fused colliculum, between 27 % and 32 % of otolith length and located slightly anterior of centre of inner face. Ventral furrow on inner face indistinct or absent (figs. 8E -F, New Providence Island specimens) or broad (fig. 8H, Long Island specimen).

Coloration. Very variable from uniformly pale to dark brown (figs. 7, 9). Dark specimens either with completely light vertical fins or with dark fin bases and light margins. A recently caught dark specimen, ZMUC P771365, 132 mm, from Eleuthera Island is unique by having dark head and body, except for a light predorsal area (fig. 7C). Elongate gill-rakers dark in all specimens, except in three specimens from Great Exuma Island (ZMUC P771363) and Long Island (AMNH 57448, USNM 274737).

Distribution and habitat. Known from the Great Bahama Bank area, with confirmed localities on five islands (Berry, New Providence, Great Exuma, Eleuthera and Long Islands (figs. 1, 10) (see Material examined). Unconfirmed records of L. spelaeotes from Andros Island (Farr & Palmer 1984, Proudlove 1984, B. Kakuk in litt. (in Cohen & McCosker 1998) and Long Island, Grand Canyon , 22°57.423’N, 74°51.238’W, east of Berrys settlement (T. Iliffe January 2005, personal observation ).

Twin Pillars Cave in Miley, southern Long Island (23°03.841’N, 74°55.503’W) was rediscovered in 2005 and is situated within a few meters of the east side of the main road. It consists of an air-filled cave with a 30 to 150 cm deep saltwater (34 ppt) pool covering most of the floor. At least 10 skylight entrances, only one of which is climbable, provide access to the cave. While many parts of the cave are well illuminated during the day, various recesses are only dimly lit. At least 24 Lucifuga were observed but not collected in 2005. Other stygobitic species from this cave include the hippolytid shrimp Barbouria cubensis , the polynoid polychaete Pelagomacellicephala iliffei , the halocyprid ostracod Spelaeoecia capax , several species of copepods and a parasitic gnathiid isopod. About 10 specimens of the latter were removed from the gill-cavity of a 109 mm SL L. spelaeotes collected in 1985 (USNM 274737).

Alphonso Dean’s Blue Hole on southern Long Island was searched for during the January2005 trip to Long Island and it was confirmed that this locality is not the same as Dean’s Blue Hole described in details by Wilson (1994). Alphonso Dean's Blue Hole (perhaps at 23°01.071'N, 74°54.085'W) in Hard Bargain could not be relocated with certainty, although a 50 m diameter, circular blue hole located between the main road and the abandoned Diamond Salt airstrip was tentatively identified by several locals as Alphonso Dean's Blue Hole. At 6 m depth, a small cave extends off the east side of this open blue hole and contains the shrimp B. cubensis , but no fish were observed. Unfortunately, a large amount of rusted metal, broken bottles, old tires and other debris have been dumped on the bank of the blue hole and may be adversely impacting the water quality.

Salinity data from the various records indicate that L. spelaeotes is a truly euryhaline species.

Specimens from New Providence Island have been collected within the upper 3-4 meter of the holes, apparently preferring the upper, warmer, brackish layer to the lower, colder, more saline water in the holes (Cohen & McCosker 1998). Recently caught specimens from Eleuthera and Great Exuma Islands, however, were captured at depths of more than 10 meters, indicating a tolerance to more saline waters. This is also the case in the two new localities on central Long Island.

In Grotto, central Long Island (fig. 10), which is a partially flooded cave, salinity was measured at 33.8 ppt. In addition to the main collapsed entrance, several smaller, skylight entrances also help to illuminate the 20 m long by 8 m wide and 2.5 m deep pool. Most of the 8-10 fish in the pool were observed in a dark alcove at the rear of the cave. Large numbers(many hundreds to thousands) of the shrimp B. cubensis were present in all parts of the pool during the day but were absent when the cave was visited after dark. This suggests that the known parts of the cave are only a small segment of a much larger and well integrated system.

In Silent Hole salinity increased from 8.4 ppt at the surface to 26 ppt at 12 m, temperature likewise rose from 23 to 26 °C, pH dropped from 8.2 to 7.3 and dissolved oxygen plummeted from 7.5 to less than 1 mg/l. Several Lucifuga were observed and one collected in the more saline water near the bottom, under a ledge, where a few B. cubensis shrimp were also found.

Remarks. Sexual dimorphism is not observed in any of the described characters. The morphology of the few specimens from Berry, Eleuthera, Great Exuma and Long Island are generally well within the ranges of the numerous specimens from New Providence Island (Table 2).

The few exceptions, such as unique coloration and longer pelvic finrays (20.0 vs. 8.0- 18.9 % SL) of the specimen from Eleuthera; weak palatine dentition and unusually small eyes of the two specimens from southern Long Island; and pale, elongated gill-rakes in the specimen from Great Exuma Island, are not enough difference to warrant status as separate species. More material is needed in order to further study the morphological and genetic plasticity of the populations on the various Islands.