Molecular Identification of the Bonefish Albula esuncula (Albuliformes: Albulidae) from the Tropical Eastern Pacific, with Comments on Distribution and Morphology
Mitochondrial DNA sequence data from a segment of the cytochrome b (cytb) gene were used to infer geographic distributions of two unnamed putative species of eastern Pacific bonefishes, Albula sp. A and Albula sp. C, both members of the A. vulpes complex. The molecular data revealed that Albula sp. C, a lineage originally identified from Panama, is distributed north to the coastal waters of central Mexico and the southern Gulf of California (Sea of Cortez). Albula sp. A, originally identified from the central Gulf of California and distributed to California, USA, is shown here to range to Mazatlán, Sinaloa, in the southern gulf where it occurs sympatrically with Albula sp. C. The distributions of the two putative species inferred from the molecular data suggest that the single available name for eastern Pacific bonefishes, Albula esuncula (Garman, 1899), originally described from larvae (leptocephali) collected off Acapulco, Guerrero, should be assigned to Albula sp. C. Morphometric and meristic analyses of adults of A. esuncula and Albula sp. A revealed no external characters that could be used reliably to distinguish between the two species. Se utilizaron datos de secuencias de ADN mitocondrial obtenidos de un segmento del gen citocromo b (cytb) para elucidar las distribuciones geográficas de dos especies putativas no nombradas de macabí del océano Pacifico Oriental, Albula sp. A y Albula sp. C, que son miembros del complejo de A. vulpes. Los datos moleculares demostraron que Albula sp. C, una línea genética identificada originalmente de Panamá, se distribuye hacia el norte hasta las aguas costeras de México central y sur del golfo de California (mar de Cortés). Se demuestra que Albula sp. A, encontrada originalmente en el golfo de California central y aguas costeras del estado de California, EUA, se distribuye hasta Mazatlán, Sinaloa, en el sur del golfo donde coincide con Albula sp. C. Con base en las distribuciones de las dos especies putativas de Albula se establece que Albula sp. C debe nombrarse A. esuncula, especie descrita originalmente de larvas leptocéfalas recolectadas en la región de Acapulco, Guerrero por Garman (1899) y único nombre disponible para los macabí del Pacifico Oriental. En relación a los análisis morfométricos y merísticos de adultos de A. esuncula y Albula sp. A, no se encontraron caracteres externos que podían ser utilizados para distinguir entre las dos especies.Abstract
Larval syntypes of Atopichthys esunculus Garman, 1899 ( = Albula esuncula) collected off Acapulco, Guerrero, Mexico, 13 April 1891; 44 and 39 mm SL. Photo from the Museum of Comparative Zoology, Harvard University, Fish Collection Database (MCZ 28430); reproduced with permission (© President and Fellows of Harvard College).
Map summarizing the distribution and showing collecting localities for Albula sp. A and Albula sp. C in the eastern Pacific for which cytochrome b sequences have been obtained (Colborn et al., 2001; Pfeiler et al., 2002; present study). Key to localities: NB, Newport Bay, California; BK, Bahía de Kino, Sonora; GY, Guaymas, Sonora; MZ, Mazatlán, Sinaloa; LC, Laguna Chautengo, near Acapulco, Guerrero; SD, San Dionisio del Mar, Oaxaca; PC, Panama City, Panama. Arrowhead indicates type locality (Acapulco) for A. esuncula. Asterisks indicate localities from which new specimens were collected for the present study. The total number of individuals sequenced for the cytochrome b gene segment from each locality from all studies cited above is shown in parentheses. ?, species identity not determined.
Landmarks (letters) and truss distances (numbers) used in the morphometric analysis of Albula spp. Key to truss distances: 1, snout to dorsal-fin origin; 2, snout to pectoral-fin origin; 3, dorsal-fin origin to pectoral-fin origin; 4, dorsal-fin base length; 5, dorsal-fin origin to pelvic-fin origin; 6, pectoral-fin origin to posterior end of dorsal-fin base; 7, pectoral-fin origin to pelvic-fin origin; 8, posterior end of dorsal-fin base to pelvic-fin origin; 9, pelvic-fin origin to anal-fin origin; 10, posterior end of dorsal-fin base to anal-fin origin; 11, posterior dorsal-fin base to posterior end of hypural plate; 12, anal-fin origin to posterior end of hypural plate.
Bayesian 50% majority rule consensus tree showing relationships among the seven individuals of Albula sp. C from Mexico, the common haplotype of Albula sp. C from Panama (ALB40; GenBank AF311760), and 13 haplotypes of Albula sp A. from Mexico, based on analysis of a 544 bp segment of the cytb gene. Bayesian posterior probabilities are shown above the branches, with bootstrap support values from the maximum parsimony tree (90 parsimony informative sites; length = 116; CI = 0.897, RI = 0.960) given below the branches. Albula nemoptera was the outgroup (not shown).
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