Ophichthid eel genus Aplatophis includes two species restricted to the New World, one distributed in the western Atlantic (A. chauliodus) and the other in the tropical eastern Pacific (A. zorro). Aplatophis zorro is a little-known species that was described in Panama, Gulf of San Miguel, from the collection of a single mature male. This work constitutes the first record of the species in Colombian waters and extends its geographical distribution to more than 483 km south on the American continent. In addition, some morphometric variation of the species, which was only known from the Panamanian holotype, is provided

Acero-P, Arturo

Stephanía Rojas-Vélez, Stephanía

Tavera, Jose

Spanish

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ReseaRch NoteAplatophis zorro (Anguilliformes: Ophichthidae), a rare fish from the Tropical Eastern Pacific: Morphometric data and range extensionAplatophis zorro (Anguilliformes: Ophichthidae), un pez raro del Pacífico oriental tropical: Datos morfométricos y extensión de su distribuciónStephanía Rojas-Vélez 1*, Jose Tavera 1 and Arturo Acero-P 21Grupo de Investigación en Sistemática, Evolución y Biogeografía Animal, Departamento de Biología, Universidad del Valle, AA 25360, Cali, Colombia2Instituto de Estudios en Ciencias del Mar (CECIMAR), Universidad Nacional de Colombia, sede Caribe, El Rodadero, Santa Marta, Colombia*Corresponding author: stephania.rojas@correounivalle.edu.coAbstract.- Ophichthid eel genus Aplatophis includes two species restricted to the New World, one distributed in the western Atlantic (A. chauliodus) and the other in the tropical eastern Pacific (A. zorro). Aplatophis zorro is a little-known species that was described in Panama, Gulf of San Miguel, from the collection of a single mature male. This work constitutes the first record of the species in Colombian waters and extends its geographical distribution to more than 483 km south on the American continent. In addition, some morphometric variation of the species, which was only known from the Panamanian holotype, is provided.Key words: Ophichthid eel, Snaggle-toothed snake-eel, Colombia, geographic range, Panama Revista de Biología Marina y OceanografíaVol. 57(3): 192-195, 2022<https://doi.org/10.22370/rbmo.2022.57.3.4100>IntroductIonOphichthidae is a family belonging to the order Anguilliformes that includes about 350 valid species, 51 of which were described in the last decade (Fricke et al. 2021). Snake eels are distributed in all tropical and temperate oceans of the world, from the shallow coast down to 800 m depth (Robertson & Allen 2015, Nelson et al. 2016). They have a variable size (total length usually 0.5-2.5 m) and a rigid tail, characteristics that allow them to move through the sediment and dig quickly to make their burrows (Nelson et al. 2016). It is distinguished from other families of the order by having posterior nostrils that cross inside the upper lip, and a gill bag expanded and reinforced by 15-49 rays called “jugostegalia” (McCosker & Rosenblatt 1995). In the tropics of the New World, about 89 species are distributed in 28 genera (Robertson & Allen 2015, Robertson et al. 2019). For this region, one of the less diverse genera is Aplatophis Böhlke, 1956, as it contains only two species, one of them distributed in the western Atlantic (Aplatophis chauliodus Böhlke, 1956) and the other in the tropical eastern Pacific (Aplatophis zorro McCosker & Robertson, 2001). Unlike A. chauliodus, which has a wide distribution ranging from the Gulf of Mexico to French Guiana, A. zorro is reported only from Gulf of San Miguel, Panama, based on the collection of a single mature male from which the species was described (McCosker & Robertson 2001). The aim of this work has been to report the extent of the distribution range of A. zorro, based on the record of individuals captured in Colombian waters and, to provide morphometric data of this little-known species.©The author(s). This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.Online ISSN: 0718-1957RBMO192MaterIals and MethodsTwo individuals of A. zorro were collected on July 15, 1979, in Malaga Bay (3°57’33”N, 77°20’ 08”W), located on the Pacific coast of Colombia (Fig. 1), between 5 and 10 m deep, on a bottom of dead vegetation (leaves) and mud. The individuals were deposited in the Reference Ichthyological Collection of Universidad del Valle with the catalog number CIR-UV 79071, under the erroneous identification of Myrichthys tigrinus Girard, 1859. Forty-one years later, after the review of the deposited material, its identification was corrected following the information system of Robertson & Allen (2015), the original description of the species (McCosker & Robertson 2001), and the description of the genus Aplatophis made by Rosenblatt & McCosker (1970).Measurements were based on McCosker & Robertson (2001). The following measurements were considered: Total length (TL), head length (HL), eye diameter, interorbital distance, pre-anal length, post-anal length, pre-dorsal length, body depth at gill opening, body width at gill opening, body depth, body width, snout length, upper-jaw length, gill-opening length, pectoral-fin length, and pectoral-fin base length (Table 1). Measurements of total length, pre-anal length, post-anal length, and pre-dorsal length were made with a 1 mm gradation ruler. For the remaining measurements a dial caliper with precision of 0.1 mm was used. Then the measurements were compared with those described in the species holotype (USNM-360118) from Panama.Figure 1. Aplatophis zorro collection locations in the eastern Pacific. Holotype collected in Gulf of San Miguel, Panama (8°12'21.6”N; 78°19'34.8”W) and two individuals collected in Málaga Bay, Colombia (3°57'33”N; 77°20'8”W) / Localidades de colecta de Aplatophis zorro en el Pacífico oriental. Holotipo colectado en el golfo de San Miguel, Panamá (8°12'21,6”N;78°19'34,8”O) y dos individuos colectados en bahía Málaga, Colombia (3°57'33”N; 77°20'8”O)Rojas-Vélez et al. RBMO 57(3): 192-195, 2022<https://doi.org/10.22370/rbmo.2022.57.3.4100>193Morphology and range extension in Aplatophis zorroresults and dIscussIonAccording to McCosker & Robertson (2001), A. zorro is distinguished by having a long and fat head, with a hump over and behind the eye; front teeth of both jaws like fangs extending far beyond the mouth when closed and a line of white dots on the sides of the head forming a letter Z on the right-side view (Fig. 2A-C). Measurements of the collected specimens compared to holotype are shown in Table 1. Although most of the measurements and proportions are similar to the holotype, head measures have larger values in the individuals presented in this work. For example, the range of variation of the eye diameter with respect to head length is extended (2.98-4.33% of HL vs. 3% in the holotype). Similarly, the interorbital distance increased to 18% of HL compared to 14% found in the holotype. Other head-associated measurements such as snout length (20-22% of HL in the Colombian material vs. 18% of HL in holotype) and upper jaw length (31-38% of HL vs. 34% in the holotype) tend also to be larger in Colombian individuals. In addition, one specimen has bigger teeth compared to the holotype since the longest tooth comprises 1.7 the diameter of the eye vs. 1.5 in the holotype. Because the measurements were made in a similar way to the description of the species, it is likely that the differences shown here correspond to intraspecific morphological variation. However, to address this variation in detail it is necessary to measure a larger number of individuals, which are hard to find, unlike its sister species in the western Atlantic.Table 1. Morphometric measurements for holotype specimen and two individuals of Aplatophis zorro at two locations in the eastern tropical Pacific / Medidas morfométricas del espécimen holotipo y de dos individuos de Aplatophis zorro en dos localidades del Pacífico oriental tropical Figure 2. Aplatophis zorro collected in Málaga Bay, Colombian Pacific (CIR-UV 79071). A) Head and pectoral fin of specimen 1 (777 mm TL), B) Head and pectoral fin of specimen 2 (662 mm TL), C) Complete body of specimen 1. Photographs by Stephanía Rojas-Vélez / Aplatophis zorro colectados en bahía Málaga, Pacífico colombiano (CIR-UV 79071). A) Cabeza y aleta pectoral de espécimen 1 (777 mm TL), B) Cabeza y aleta pectoral de espécimen 2 (662 mm TL), C) Cuerpo completo de espécimen 1. Fotografías de Stephanía Rojas-VélezRojas-Vélez et al. RBMO 57(3): 192-195, 2022<https://doi.org/10.22370/rbmo.2022.57.3.4100>194Morphology and range extension in Aplatophis zorroSeveral specimens of A. chauliodus collected in Puerto Rico, Panama, Gulf of Mexico, Colombia, Venezuela, and French Guiana have been deposited in museums (Böhlke 1956, Cervigón 1966, Uyeno et al. 1983, McCosker et al. 1989). Nevertheless, there was only one specimen of A. zorro deposited at United States Natural Museum USNM-360118. Given its morphological uniqueness, McCosker & Robertson (2001) indicated it is unlikely that additional specimens of A. zorro were misidentified in biological collections. However, the two specimens reported in this paper are an example of a previous mistake in the identity of this snake eel. This record precedes the description of the species by 22 years and information and specific references to this and other species in the region were scarce or unavailable to the authors that collected and identified the species in the first place, two decades before.The wide diversity in adaptations and ecology of these eels may be the reason why few individuals of A. zorro have been collected to date. For example, the burrowing behavior of snake eels can make it difficult to capture individuals and to understand their distribution (McCosker & Robertson 2001). The report of these specimens indicates that much remains to be known about the marine fish fauna of this region and that the soft-bottom fauna needs to be explored further. These data add more information about these rare snake eel species, but there are at least another six cases of New World ophichthids that are still known from a single specimen which deserves further attention (McCosker & Robertson 2001). For example, it is recommended to support morphological analyzes with molecular data that allow validating the identity of these species.acknowledgMentsThe authors thank Universidad del Valle for the facilities to analyze the samples. To Professor Efraín Rubio for the collection of the study specimen and to Manuel Francisco Cano for map design. Contribution No. 549 of Instituto para el Estudio de las Ciencias del Mar (CECIMAR), Universidad Nacional de Colombia sede Caribe.lIterature cItedBöhlke JE. 1956. A small collection of new eels from western Puerto Rico. Notulae Naturae 289: 1-13.Cervigón F. 1966. Los peces marinos de Venezuela, 436 pp. Fundación La Salle de Ciencias Naturales, Caracas. Fricke R, WN Eschmeyer & R van der Laan. 2021. Eschmeyer‘s catalog of fishes. <http://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp>McCosker JE & DR Robertson. 2001. Aplatophis zorro, a new species of eastern Pacific snake-eel, with comments on New World ophichthid distributions (Anguilliformes: Ophichthidae). Revista de Biología Tropical 49(Supl. 1): 13-19.McCosker JE & RH Rosenblatt. 1995. Ophichthidae. In: Fischer W, F Krupp, W Schneider, C Sommer, KE Carpenter & VH Niem (eds). Guía FAO para la identificación de especies para los fines de la pesca. Pacífico centro-oriental, pp. 1326-1341. FAO, Roma.McCosker JE, EB Böhlke & JE Böhlke. 1989. Family Ophichthidae. In: Böhlke EB (ed). Fishes of the Western North Atlantic, Part nine, Vol. 1: Orders Anguilliformes and Saccopharyngiformes, pp. 254-412. Sears Foundation for Marine Research, Yale University, New Haven. Nelson JS, TC Grande & MV Wilson. 2016. Fishes of the world, 752 pp. John Wiley and Sons, Hoboken.Robertson DR & GR Allen. 2015. Shorefishes of the Tropical Eastern Pacific: online information system. Version 2.0 Smithsonian Tropical Research Institute, Balboa, Panamá <http://biogeodb.stri.si.edu/sftep/es/pages>Robertson DR, EA Peña, JM Posada & R Claro. 2019. Shorefishes of the Greater Caribbean: online information system. Version 2.0 Smithsonian Tropical Research Institute, Balboa, Panama. <https://biogeodb.stri.si.edu/caribbean/en/pages>Rosenblatt RH & JE McCosker. 1970. A key to the genera of the ophichthid eels, with descriptions of two new genera and three new species from the eastern Pacific. Pacific Science 24: 494-505.Uyeno T, K Matsuura & E Fujii. 1983. Fishes trawled off Suriname and French Guiana, 519 pp. Japan Marine Fish Resource Research Center, Tokyo.Received 10 November 2021Accepted 26 September 2022Rojas-Vélez et al. RBMO 57(3): 192-195, 2022<https://doi.org/10.22370/rbmo.2022.57.3.4100>195Morphology and range extension in Aplatophis zorro

Aplatophis zorro (Anguilliformes: Ophichthidae), a rare fish from the Tropical Eastern Pacific: Morphometric data and range extension

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Aplatophis zorro (Anguilliformes: Ophichthidae), a rare fish from the Tropical Eastern Pacific: Morphometric data and range extension : Aplatophis zorro (Anguilliformes: Ophichthidae), un pez raro del Pacífico oriental tropical: Datos morfométricos y extensión de su distribución

Aplatophis zorro (Anguilliformes: Ophichthidae), a rare fish from the Tropical Eastern Pacific: Morphometric data and range extension : Aplatophis zorro (Anguilliformes: Ophichthidae), un pez raro del Pacífico oriental tropical: Datos morfométricos y extensión de su distribución

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