Abstract
Knowledge of taxonomy, systematics and life histories of the skates that inhabit the Gulf of California is scarce. Five species have been documented in the Sea of Cortez: R. cortezensis, R. equatorialis, Raja inornata, R. rhina and R. velezi. The California skate (R. inornata) is the most abundant species caught as by-catch during the hake trawl fishery in the Gulf. Intraspecific variation in the external morphology of R. inornata from the northern Gulf of California, México is described on the basis of 24 proportional morphometric variables from 45 males (227–525 mm total length TL) and 52 females (226-690 mm TL). Males and females had 9 and 14 proportional dimensions respectively that were isometric with total length (TL). Regression slope and elevation analysis revealed that 9 relationships between TL and morphometric variables were sexually dimorphic. A stepwise discriminant function separated three groups of skates (females and males of R. inornata and males of Raja cortezensis) and was able to correctly classify 97%, 100% and 100% of the original grouped cases, respectively. The variables that best discriminated between species and sexes were preorbital length, preoral length, distance between fifth gill openings, maximum distance between pelvic fins, and distance from cloaca to anterior caudal fin. The study also revealed that several of the meristic characters examined showed considerable variation and, therefore, should be used with caution in taxonomic studies.References
Aguiar A.A., Gallo, V., & Valentin, J.L. (2004) Using the size independent discriminant analisis to distinguis the species of Myliobatis Cuvier (Batoidea: Myliobatidae) from Brazil. Zootaxa 464: 1–7.
Badyaev, A. (2002) Growing apart: an ontogenetic perspective on the evolution of sexual size dimorphism. TRENDS in Ecology & Evolution 17, August 2002: 369–378.
Bass, A.J. (1973) Analysis and description of variation in the proporcional dimensions of Scyliorhinid, Carcharhinid and Sphyrnid sharks. South African Association for Marine Biological Research. Oceanographic Research Institute Investigational Report 32, 1–28.
Bigelow, H.B. & Schroeder, W.C. (1953) Fishes of the western North Atlantic. Sawfishes, guitarfishes, skates and rays, and chimaeroids. Memoirs Sears Foundation Marine Research. 1(2).
Braccini, J.M. & Chiaramonte, G.E. (2002) Intraspecific variation in the external morphology of the sand skate. Journal of Fish Biology 61, 959–972. doi:10.1006/JFBI.2002.2111.
Castillo-Geniz, J.L. (1992) Diagnóstico de la Pesquería de Tiburón de México. Instituto Nacional de la Pesca, Secretaría de Pesca, México, D.F. 76 pp.
Castro-Aguirre, J.L., Arvizu, M.J., & Páez, J.B. (1970) Contribución al conocimiento de los peces del Golfo de California. Revista de la Sociedad Mexicana de Historia Natural, Tomo XXXI, 107–181.
Castro-Aguirre, J.L. & Espinosa P.H. (1996) Listados Faunísticos de México. VII. Catálogo Sistemático de las Rayas y Especies Afines de México (Chondrichthyes: Elasmobranchii: Rajiformes: Batoideiomorpha). Instituto de Biología, Universidad Nacional Autónoma de México. 75 pp.
Chirichigno, N. (1973) Nuevas especies de peces de los géneros Mustelus (Fam. Triakidae), Raja (Familia Rajidae) y Schedophilus (Fam. Centrolophidae). Informe Instituto del Mar del Perú-Callao 42:1–40.
Compagno, L.J.V. (2005) Checklist of Living Chondrichthyes, In: W.C. Hamlett. (Ed.), Reproductive biology and phylogeny of Chondrichthyes: Sharks, batoids, and chimaeras. Series Reproductive Biology and Phylogeny, University of Queensland, Science Publishers 503–548.
Eschmeyer, W.N., Herald, E.S. & Hammann, H. (1984) A field guide to Pacific coast fishes of North America from the Gulf of Alaska to Baja California. Hougton Mifflin Co., Boston, Massachusetts.
Fairbairn, D.J. (1997) Allometry for sexual size dimorphism: Pattern and Process in the coevolution of body size in males and females. Annual Review Ecology Systematics 28: 659–87.
Feduccia, A. & Slaughter, B. H. (1974) Sexual dimorphism in skates (Rajidae) and its posible role in diffferential niche utilization. Evolution 28, 164–168.
Gould, S.J. (1965) Allometry and size in ontogeny and phylogeny. Biological Reviews. 41: 587–640.
Hubbs, C.L. & Ishiyama, R. (1968) Methods for the taxonomic study and description of skates (Rajidae). Copeia, 1968, 483–491.
Ishihara, H. (1987). Revision of the Western North Pacific Species of the Genus Raja. Japanese Journal of Ichthyology. Vol. 34, No. 3: 241–285.
Ishihara, H. & Ishiyama, R. (1985) Two New North Pacific Skates (Rajidae) and a Revised Key to Bathyraja in the Area. Japanese Journal of Ichthyology. 32(2): 143–179.
Ishiyama, R. (1958) Studies on the rajid fishes (Rajidae) found in the waters around Japan. Journal of the Shimonoseki College of Fisheries, 7(2/3): 193–394, pls. 1–3.
Ishiyama, R. (1967) Fauna Japonica. Rajidae (Pisces). Bulletin of the Biogeographical Society of Japan, Tokyo, vi+84 pp., 32 pls.
Jordan, S.D. & Bollman. C.H. (1890) Descriptions of new species of fishes collected at the Galápagos Islands and along the coast of the United Status of Colombia, 1877–88. Proceedings of the United States National Museum 12: 149–183.
Jordan, S.D. & Gilbert, C.H. (1880) Description of a new species of ray, Raja rhina, from the coast of California. Proceedings of the United States National Museum 3: 251–253.
Jordan, S.D. & Gilbert, C.H. (1881) Description of a new species of ray (raia stellulata) from Monterrey, California. Proceedings of the United States National Museum, Vol. IV. 27:133–135.
Kajiura, M.S. & Tricas, T.C. (1996) Seasonal dynamics of dental dimorphism in the atlantic stingray Dasyatis Sabina. The Journal of Experimental Biology (199): 2297–2306.
Leible, M.D. (1988). Revisión de métodos para estudios taxonómicos de rayas (Rajiformes, Rajidae). Gayana Zoologica 52, 15–93.
Mamuris, Z., Apostolidis, A.P., Panagiotaki, P., Theodorou, A.J. & Triantaphyllidis, C. (1998) Morphological variation between red Mollet populations in Greece. Journal of Fish Biology 52, 107–117.
MacLeod, N. & Forey, P.L. (2002) Introduction: morphology, shape, and phylogenetics. In: Morphology, Shape and Phylogeny. Systematics Association Special Volume Series 64. MacLeod, P. and P. L. Forey (Eds.) 1–7.
McEachran, J.D. (1976) Reply to “Sexual dimorphism in skates (Rajidae)”. Evolution 31, 218–220.
McEachran, J.D. (1977) Variation in Raja garmani and the status of Raja lentiginosa (Pisces: Rajidae). Bulletin of Marine Science, 27(3): 423–439.
McEachran, J.D. & Compagno, L.J.V. (1979) A further description of Gurgesiella furvescens with comments on the interrelationships of Gurgesiellidae and Pseudorajidae (Pisces:Rajoidei), Buletin Marine Science, 29:530–553.
McEachran, J.D. & Matheson, R.E. Jr. (1985) Polychromatism and Polymorphism in Breviraja spinosa (Elasmobranquii, Rajiformes), with Description of Three New Species. Copeia 1985, 1035–1052.
McEachran, J.D. & Miyake, T. (1984) Comments on the skates of the tropical eastern pacific: one new species and three new records (Elasmobranchii: Rajiformes). Proccedings of. The Biological Society of Washington. 97(4), pp. 773–787.
McEachran, J.D. & Miyake, T. (1988) A new species of skate from the Gulf of California (Chondrichthyes, Rajoidei). Copeia 1988, 877–886.
McEachran, J.D. & Miyake, T. (1990) Zoogeography and bathymetry of skates (Chondirchthyes, Rajoidei) In: Pratt, H.L. Jr., Gruber, S.H., and Taniuchi, T. (Eds.), Elasmobranchs as Living Resources: Advances in the Biology, Ecology, Systematics, and the Status of the Fisheries. National Oceanic and Atmospheric Administration, Technical Report, National Marine Fisheries Service 90: 305–326.
McEachran, J.D. & Notarbartolo di Sciara, G. (1995) Peces Batoideos. En: Fischer, W., Krupp, F., Schneider, W., Sommer, C., Carpenter, K. E. & Niem, V. H. (Eds.). Guía FAO para la identificación de especies para los fines de la pesca. Pacífico centro-oriental. Volumen II. Vértebrados – Parte 1. Roma, FAO, Vol. II: 647–1200 p.
McEachran, J.D. & Stehmann, M. (1984) A new species of skate, Neoraja carolinensis, from off the southeastern United States (Elasmobranchii: Rajoidei). Proceedings of the Biological Society of Washington 97, 724–735.
McEachran, J.D., Seret, B. & Miyake, T. (1989) Morphological variation within Raja miraletus and Status of R. ocellifera (Chondrichthyes, Rajoidei). Copeia 1989, 629–641.
McGarigal, K., Cushman, S. & Stafford, S. (2000) Multivariate Statistics for Wildlife and Ecology Research. Springer–Verlag, New York. 283 pag.
Peters, R.H. (1983) The ecological implications of body size. Cambridge University Press. 329 p.
Shea, B.T. (1985) Bivariate and multivariate growth allometry: statistical and biological considerations. Journal of Zoology, London 206, 367–390.
Siqueiros-Beltrones, D. A. (1990) Morphometric analysis of sharks of the genus Carcharhinus Blainville, 1816: C. limbatus (Valenciennes, 1841) and C. brevipinna (Müller & Henle, 1841) from Mexican waters. Scientia Marina 54, 349–358.
StatSoft (1998) STATISTICA for Windows (Volumen I & III), (2nd. Edition). StatSoft, Inc.
Sáez, S. & Lamilla, J. (2004) Sexual homodonty in Bathyraja griseocauda (Norma 1937) from the Southern Eastern Pacific (Chile) (Chondirchthyyes, Rajidae: Arhynchobatidae). Journal of Applied Ichthyology 20, 189–193.
Zar, J.H. (1999) Biostatistical Analysis, 4th edn. New Jersey, Prentice Hall. 663 pp.