Presence of Ruvettus pretiosus (Gempylidae) in the Colombian continental Caribbean

The first record of Ruvettus pretiosus Cocco, 1833 for the Colombian continental Caribbean is presented. The specimen was collected at Los Cocos, department of Magdalena (11° 16’ 33, 84’’ N 73° 53’ 33, 01’’ W), using a demersal longline gear placed at 100 m depth. Biometrics, diagnosis and comments regarding its distribution, ecology and biology are included in the description. This new record expands the distribution of the species in the Caribbean Sea and increases the reported number of gempylids for Colombia to five.


Introduction
Biodiversity of marine fauna in the tropical zone is concentrated in two conspicuous peaks, one in the Indo-Pacific Ocean and the other one in the Atlantic Ocean, specifically in the southern Caribbean Sea (Briggs, 2007).This zone acts as a centre of origin and evolutionary radiation and includes the Colombian Caribbean Sea.This zone is characterized by a high fish diversity represented by hard bottom, demersal, and pelagic species, occupying all the available ecosystems, including deep-sea.Despite its importance, fish biodiversity in Colombia is poorly understood and the discovery of a new species must be incorporated into existing databases (Díaz & Acero, 2003;Rey & Acero, 2015).Recently, the cataloguing action and the new distributional records have acquired a new urgency through the fact that global biodiversity is changing and declining under multiple mounting threats (Bello et al. 2014).The majority of the marine fishes compromising the existing baseline is related to shallow reef and estuarine areas, with the existing fish fauna in oceanic and deep environments still being relatively unknown (Roa-Varón et al. 2003).
The family Gempylidae, comprising 16 genera and 24 species, is associated with mesopelagic and benthopelagic environments.Gempylids are primarily distributed in tropical, subtropical, and temperate areas worldwide, with little being known about them, both in Colombia and around the world (Nakamura & Parin, 2002;Lopes et al. 2003).Species included in this family are characterized by short snouts, presenting two nostrils on each side of the head, large and non-protractible mouth, sometimes possessing two strong fang teeth in the upper jaw or a pair in the front of the lower

Presence of Ruvettus pretiosus (Gempylidae) in the Colombian continental Caribbean original article
Bogotá jaw.Gempylid species have varying body shape, forked caudal fin, two dorsal fins and finlets.The lateral line is inconspicuous and the skin is notoriously rough.They can reach total lengths of up to 3 m (Nakamura & Parin, 2002).

Materials and Methods
The examined specimen was captured on October 21, 2009 and was part of the artisan fish landings in Los Cocos (11° 16' 33, 84'' N 73° 53' 33, 01'' W) (Figure 1) - Magdalena Department, Colombian Caribbean.The specimen was obtained using an artisanal demersal horizontal longline, made of nylon and equipped with 200 hooks (No 7) (Cuellar, 2010), and targeted at 100 m depth.Los Cocos is located in the Colombian Caribbean coast and is under the influence of the north-south movement of the Intertropical Convergence Zone (ZCIT) and the movements of trade winds.These movements lead to upwelling events that increase nutrients in the surface layers, enriching phytoplankton communities and delineating high productivity zones for the area (Franco-Herrera, 2005).
The specimen was analysed at the facilities of the Universidad de Bogotá Jorge Tadeo Lozano, Santa Marta campus.Biometrics (meristic and morphometric data) were collected following Nakamura & Parin (2002).The specimen was fixed in 4 % formalin, preserved in 70 % alcohol, and introduced into the Colombian Marine Natural History Museum at the Marine and Coastal Research Institute INVEMAR (INV-PEC9011), Fish collection (Figure 2).
The collected biometric data considered for the species identification followed Bettoso & Dulčić (1999) and are presented in Table 1.

Results and discussion
One specimen of R. pretiosus was obtained for first time by a coastal artisan fishery during the research project 'Bio-economical valuation of artisanal fisheries with emphasis on the current determination of maturity mean lengths of fish species with commercial importance, in the disembarking sites located between Tasajera and La Jorará (Department of Magdalena).' Detailed information about our documented record is presented below, which is in agreement with the treatment of first record material and related data proposed by Bello et al. (2014) for the first reports in ichthyology.(Eschmeyer, 2015).
Size: Specimen TL of 881 mm.Keller & Kerstetter (2014) reported a TL range (cm) between 19.0 and 88.5 cm from a sample of 56 individuals collected in the Gulf of Mexico and western North Atlantic.
Morphometrics: Body height is typically 4.3 to 4.9 times the standard length (the specimen examined: 4.6) and the head length 3.3 to 3.7 times the standard length (specimen: 3.5) (Nakamura & Parin, 2002).Morphometric characteristics of the studied specimen are presented in Table 1.

Coloring:
The body of living adults is brown to dark brown and the tips of the pectoral and pelvic fins are black.In juvenile, the edges of the second dorsal and anal fins are white (Nakamura & Parin, 1993).
Biology and reproduction: R. pretiosus migrates during the night for food and feeds on cephalopods and teleost fishes from the orders Gadiformes, Perciformes and Anguilliformes (Vasilakopoulos et al. 2011;Viana et al. 2012).It is a solitary, gonochoristic species with no evidence of sexual reversals being observed.Testes are white and ovaries pink.Populations exhibit a bathymetric stratification by sex: males are usually found in deep areas while females inhabit shallower waters in relation to food supply during the spawning period (July -August) (Vasilakopoulos et al. 2011).
Fishery: Associated with industrial tuna fishing, its catch is very low at the artisanal level (Nakamura & Parin, 2002).

Distribution:
For the western Atlantic it has been reported in the eastern part of Bermuda, Cuba, Haiti and the Florida Keys in the Caribbean (Nakamura & Parin, 2002); for the Colombian Pacific in Gorgona and Malpelo Islands (Rubio et al. 1992;UNESCO, 2005), but also in the Galapagos Islands and the coastal marine waters of Ecuador and Peru (Cabanilla, 2007).
The presence of R. pretiosus described as a macro-carnivorous fish with a calculated trophic level of 4.2 ± 0.57 (Fishbase.org) in the continental slope of the Colombian Caribbean Sea, could be related to several areas of high concentration of commercially important deep-sea crustaceans (i.e.Aristaeomorpha foliacea, Pleoticus robustus, Penaeopsis serrata; Metanephrops binghami) located between 200-550 m depth and described in recent studies (Paramo & Saint-Paul 2012a, 2012b, 2012c).Additionally it could be due to the presence of complex demersal fish assemblages (Paramo et al. 2012).Both factors can be explained by the contribution of important sources of organic matter from the phyto-detritus of the pelagic zone exported from upwelling productive areas to the demersal and deep-sea ecosystems (Rice et al. 1986).

Conclusion
This manuscript confirms the presence of R. pretiosus in the continental waters of the Colombian Caribbean Sea and raises the number of species of the family Gempylidae reported in Colombia to five.This species is rarely found in artisanal fishery catches and occurs in deeps waters, which is why many of its biological and ecological traits are unknown.Future studies on the species and its populations are required in order to determine its role in the demersal fish assemblages.