Lucifuga gibarensis, Hernández & Møller & Casane & García-Machado, 2020

Hernandez, Damir, Moller, Peter Rask, Casane, Didier & Garcia-Machado, Erik, 2020, A new species of the cave-fish genus Lucifuga (Ophidiiformes, Bythitidae), from eastern Cuba, ZooKeys 946, pp. 17-35 : 17

Lucifuga gibarensis sp. nov. Figures 1 , 2 , 3 ; Tables 1, 2 Common name: Gibara cave brotula (English)

Lucifuga dentatus variety holguinensis Díaz-Pérez et al., 1987b: 44.

Lucifuga dentatus var. holguinensis Hernández 2005: 15; García-Machado et al. 2011: 471.

Lucifuga holguinensis Proudlove 2019.

Holotype.

MFP 18.000420, 89.3 mm SL, female, Aguada de Macigo cave, ca. 21°09'42"N, 76°14'55"W, near Gibara municipality, Northern Holguin province, Cuba, collected by Eduardo Nieto, in 1986, designated as Lucifuga dentatus variety holguinensis by Díaz-Pérez et al. (1987b).

Paratypes.

MFP 18.000399, 69.3 mm SL, male, Tanque Azul cave, ca. 21°12'6"N, 76°13'59"W, near Gibara municipality, Northern Holguin province, Cuba, collected by Alfredo García-Debrás, 2 June 1997; MFP 18.000278, 89.2 mm SL, male, Aguada de Macigo cave, Gibara municipality, Northern Holguin province, Cuba, collected by Arturo Rojas, 21 November 2014; ZMUC P771732, 45.0 mm SL, male, Cueva El Baga, ca. 21°11'51"N, 76°14'3"W, near Gibara municipality, northern Holguin province, Cuba, collected by Katrine Worsaae and Peter Rask Møller, 27 November 2014.

Diagnosis.

Dorsal fin rays 72-90; anal fin rays 58-72; pectoral fin rays 15-17, caudal fin rays 10; palatine teeth absent; rakers on anterior gill arch 17-19 (long gill-rakers 3); occiput and area between lateral canal and preopercular canal scaled; diameter of pigmented eyes 1.1-1.9% SL; total vertebrae 50-53.

Description.

Meristic and morphometric characters are given in Tables 1 , 2 . Body moderately elevated behind the head, with a slight depression in the interorbital region (Figs 2 , 3 ). Eyes pigmented (similar to the condition present in L. spelaeotes and L. lucayana ( Møller et al. 2006)). Anterior gill arch with three elongate rakers and 14-16 low dentigerous pads. The areas between lateral canal and preopercular canal, and the occiput are scaled (Fig. 2 ). Caudal fin free (not fused with dorsal and anal fins). In the lateral line series of sensory neuromasts, the upper and anterior count with 13-15, the lower and posterior with 30-35. Teeth are present on the premaxillae (5-7 rows), dentaries (6 or 7 rows) and vomer (2 or 3 rows in two separate patches). Palatines without teeth.

Coloration.

Uniformly brown or light brown, with lighter fins and naked parts on the head. Nevertheless, one juvenile specimen (ZMUC P771732) was very pale, but still with tiny dark pigment dots (Fig. 3b ).

Distribution and habitat.

Lucifuga gibarensis shows a very restricted known distribution, in a lithographically isolate karst patch of caves at the north of Gibara municipality, Holguín province, without any overlap with other Cuban species of the genus (Fig. 1 ; García-Machado et al. 2011; Hernández et al. 2016). It is ca. 800 km away from the nearest L. dentata , L. subterranea and L. simile distribution areas. The distance to the Bahamian species on Little Bahama Bank ( L. lucayana ) and Great Bahama Bank ( L. spelaeotes ) is ca. 650 km and 240 km, respectively. The location area is composed by three caves (Aguada de Macigo, Tanque Azul and Cueva El Baga) located near to the shore ca. 3-15 km from each other ( Corella et al. 2000, Dietz 2015). The Aguada de Macigo cave is the type-locality with an emergent large doline, ca. 22 m deep and salinity of 16 ppt. According to Díaz-Pérez et al. (1987b), the individual designated as holotype was caught at 12 m depth.

Etymology.

The specific epithet refers to the village of Gibara, where the three caves inhabited by this species are located. We do not follow variety epithet used by Díaz-Pérez et al. (1987b), since the L. gibarensis better describes the narrow distribution of the species near the village Gibara instead of the entire region Holguin.

Genetic distances.

Among Cuban species, García-Machado et al. (2011) have demonstrated that L. gibarensis [at that time as L. dentata var. holguinensis ] is not phylogenetically close to L. dentata by showing a large mitochondrial DNA divergence of 30.5% (16.5% with cytochrome b gene) as well as several diagnostic nucleotide variations at nuclear genes. In contrast, L. gibarensis is phylogenetically closely related to other two lineages of undescribed species of Lucifuga from Cuba (named Lucifuga sp. 3 and L. sp. 4) ( García-Machado et al. 2011). However, genetic distance to both Bahamian species is not yet known.

Comparisons.

Based on external appearance, Lucifuga gibarensis sp. nov. resembles the Cuban species L. dentata (from which it was designated as variety, see Díaz et al. 1987b) and L. simile . Nonetheless, it differs in several characters: e.g., number of caudal fin rays (10 vs. 8), diameter of the pigmented eyes (1.1-1.9 vs. 0.0-0.2% SL), lack of palatine teeth vs. present and scaled occiput vs. naked or weakly scaled occiput. It also differs in dorsal and anal fin rays mean number (fewer than L. dentata and more than L. simile ) (Table 1 ).

Lucifuga gibarensis sp. nov. also resembles L. subterranea in the lack of palatine teeth and the scaled occiput, but it differs in the body moderately elevate behind the head vs. little elevated (see maximum height in Table 1 ), number of pectoral fin rays (15-17 vs. 10-13), number of caudal fin rays (10 vs. 8), the diameter of the pigmented eyes (1.1-1.9 vs. 0.0-0.3% SL) and in the number of rakers on the anterior gill arch 17-19 vs. 12-17 (Table 1 ).

Finally, Lucifuga gibarensis resembles both Bahamian species in the head profile, the number of caudal fin rays (10), the occiput scales (similar to L. spelaeotes and less scaled than L. lucayana ) and in the presence of relatively large pigmented eyes (Table 1 ). With L. lucayana it also shares the lack of palatine teeth. It differs in the number of pectoral fin rays (15-17 vs. 17-18 in L. lucayana and 17-20 in L. spelaeotes ); and diameter of pigmented eye is larger than in L. lucayana (1.1-1.9 vs. 0.9-1.0% SL).

Remarks.

It has been demonstrated that L. gibarensis is not phylogenetically close to L. dentata . The estimate of mtDNA genetic divergence between these two lineages is huge (P = 30.5%) and several diagnostic nucleotide changes at the intron 4 of calmoduline gene and intron 1 of the homeodomain EVX gene were described ( García-Machado et al. 2011). Designation as a variety of L. dentata , was wrong as judgment, given the sharp differences observed at three major morphological characters: palatine teeth; number of caudal fin rays; and degree of pigmentation in the eyes. Particularly, the number of caudal fin rays (10) and pigmented eyes were realised in L. spelaeotes description ( Cohen and Robins 1970), and recognised as diagnostic characters to distinguish the Cuban and Bahamian species at that time ( Cohen and Robins 1970; Møller et al. 2006).

As a result of the present study, we describe a new species, Lucifuga gibarensis , which is supported by morphology and molecular phylogenetic analysis ( García-Machado et al. 2011). We found unique diagnostic characters that distinguish this species from all the species described so far. Díaz-Pérez et al. (1987b) identified this taxon as a variety of Lucifuga dentata ( L. dentata var. holguinensis ), and recognised the presence of 10 caudal fin rays and pigmented eyes (characters distinguished by Cohen and Robins (1970) as important to separate L. spelaeotes from the two Cuban species known at that time), but underestimated the taxonomic relevance of these characters and avoid them. They also underrated the absence of palatine teeth vs. present in L. dentata , a useful taxonomic character to distinguish Lucifuga species (see Poey 1858; Møller et al. 2006). Furthermore, Møller et al. (2006) pointing out that the Bahamian species differing from all four Cuban species formerly known by having higher caudal fin rays number (10 vs. 8), larger pigmented eyes diameter (0.7-1.8 vs. 0.0-0.3% SL), higher vertebrae number (50-55 vs. 45-48), and higher pectoral fin rays number (17-20 vs. 10-17) supporting the hypothesis that Bahamas and Cuba are represented by two different evolutionary lineages (see also Vergara 1980, 1981). However, the new Cuban species L. gibarensis , shared a similar combination of these characters with Bahamian species apart from low number of pectoral fin rays in L. gibarensis . Based on these characters, our results do not support that lineages are confined to only one Archipelago. With the available knowledge, species with reduced or completely absence of eyes and 8 fin rays are only found in western Cuba; but species having pigmented eyes and 10 caudal fin rays are found in both archipelagos. Detailed phylogenetic studies including all Atlantic Lucifuga spp. will be crucial to clarify the phylogeographic relationships between the Cuban and Bahamian members of this genus.

Figures

Figure 1. Sample sites of Lucifuga gibarensis sp. nov. in eastern Cuba.

Figure 2. Lucifuga gibarensis sp. nov. Holotype, MFP 18.000420, 89.3 mm SL, female, Aguada de Macigo cave, Gibara municipality, Northern Holguin province, Cuba.

Figure 3. Lucifuga gibarensis sp. nov. in Cueva El Baga, Gibara municipality, northern Holguin province, Cuba, a unsampled specimen, 27 November 2014 b ZMUC P 771732, 45.0 mm SL, male, photo taken immediately prior to collection.