Occurrence of Hydrolagus macrophthalmus (Chondrichthyes: Holocephali: Chimaeridae) in the northeastern Pacific

Presencia de Hydrolagus macrophthalmus (Chondrichthyes: Holocephali: Chimaeridae) en el Pacífico nororiental

Adrián F. González–Acosta^{1 *}, José Luis Castro–Aguirre¹, Dominique A. Didier², Rafael Vélez–Marín³ and Luis A. Burnes–Romo¹

¹ Centro Interdisciplinario de Ciencias Marinas, Intituto Politécnico Nacional, Colección Ictiológica, Avenida Instituto Politécnico Nacional s/n, Col. Playa Palo de Santa Rita, 23096, La Paz, Baja California Sur, México.

³ Centro Regional de Investigación Pesquera, Manzanillo. Apartado postal 591, 28200, Manzanillo, Colima, México.

^*Correspondent:
aacosta@ipn.mx

Recibido: 16 enero 2009
Aceptado: 17 julio 2009

Abstract

Key words: chimaerid fish, TEP, México, first record, range extension.

Resumen

Se registra por primera vez la presencia de la quimera Hydrolagus macrophthalmus De Buen, 1959, en aguas del Pacífico nororiental; especie cuya distribución se consideraba como exclusiva del Pacífico sur oriental. El 13 de abril de 1995, se recolectó 1 ejemplar macho (945 mm TL) en la superficie del mar frente a Manzanillo, Colima (México: 18° 30'N, 104° 15'O), en una zona de gran profundidad (2 000 m). Su presencia, incrementa el número de quimeras del Pacífico nororiental y asimismo, amplía su distribución hacia el hemisferio norte.

Palabras clave: quimera, POT, México, primer registro, ampliación de ámbito.

The family Chimaeridae (Subclass Holocephali) includes 25 species within 2 genera that can be distinguished by the presence (Chimaera, 7 species) or absence (Hydrolagus, 18 species) of an anal fin (Bigelow and Schroeder, 1953). Several species of Hydrolagus are present in every ocean except the Arctic and Antarctic seas (Didier, 1995, 2004). Eight species occur in the Indo–Pacific Ocean and 6 in the Atlantic. In the eastern Pacific, there are 4 described species: H. alphus Quaranta, Didier, Long and Ebert, 2006, H. macrophthalmus De Buen, 1959, H. mccoskeri Barnet, Didier, Long and Ebert 2006, and H. colliei (Lay and Bennett, 1839) is endemic to the northeastern Pacific from Alaska to latitude 24° N, with an isolated population in the north–central portion of the Gulf of California (Miller and Lea, 1972; Didier and Rosenberger, 2002; Castro–Aguirre et al., 2005; Barnett et al., 2006).

We report the first occurrence of H. macrophthalmus in the northeastern Pacific. A single male specimen (945 mm TL; Fig. 1) was found floating dead on 13 April 1995 off Manzanillo, Colima (Mexico: 18° 30'N, 104° 15'W) at the surface by local fishermen over deep water (2 000 m). It was preserved with 10% formalin and identified using the description of De Buen (1959) and identification keys (Didier, 2004; Andrade and Pequeño, 2006; Quaranta et al., 2006). Body measurements (nearest mm) followed the methods, terms, and acronyms of Quaranta et al. (2006). The specimen is housed in the Ichthyological Collection of the Centro Interdisciplinario de Ciencias Marinas, Instituto Politécnico Nacional in La Paz, B.C.S. (CICIMAR–CI: 6370).

Diagnostic features are: anal fin absent; body slender with angular snout tip and very large eyes (22.4% HDL); pelvic claspers bifid, divided distally for one half their length (Fig. 2A), bearing fleshy denticulate lobes at the tips; pelvic claspers extending posterior to the distal edge of pelvic fins; frontal tenaculum (18.18% HDL, 63% EYL) with hooks decreasing in size proximally and divided into three line of hooks (left: 12, central: 13, right: 11); lateral margins of the pre–pelvic tenacula containing three hooks; anterior lobe of the second dorsal fin higher than posterior lobe, with shallow notch at the midpoint; distance from insertion of pelvic fins to origin of dorsal caudal fin lobe long and slender (> 60% BDL); pectoral fins large (20.5% BDL), extending posterior to the insertion of pelvic fins; presence of five pores anterior to the occipital canal; oral and preopercular lateral line canals sharing a short common branch from the infraorbital canal (Fig. 2B); lateral line canal of the trunk without sinusoidal undulations; uniform brown coloration without white marks on flanks. Other comparative measurements based on the holotype, the specimen herein reported and other materials (see Material Examined section) are presented in Tables 1 and 2.

The specimen was compared with the other 2 species reported in the region: H. alphus and H. mccoskeri, which according to Quaranta et al. (2006) differ in their endemic distribution in the Galapagos Islands and by size and coloration. Also, H. macrophthalmus is distinguishable from H. alphus by its uniform brown coloration, pointed snout (not blunt), greater eye length, size (> 60% in body length vs. < 57%), an elongate and slender morphology of tail region (> 60% BDL), and the presence of three hooks in the pre–pelvic tenacula (Quaranta et al., 2006). Some differences in morphometrics between H. macrophthalmus from South and Central America could be consequence of an unequal ontogenetic stage.

The presence of H. macrophthalmus had been previously reported only from the southeastern Pacific, based on type specimens from Chile and material from Peru (De Buen, 1959; Chirichigno, 1968; Quaranta et al., 2006). Therefore, the new occurrence constitutes a very large range extension for this species and the second record of chimaeroid species from the northeastern Pacific. The discovery of H. macrophthalmus increases knowledge of our marine ichthyofauna and provides evidence of a broader distributional pattern of this group, as commonly observed in some chimaeroid species (Quaranta et al., 2006). More exploration in this area will be welcomed to explore the submarine canyons and mountains in the deep pre–abyssal waters inhabited by this species which could contribute to confirm its distribution in the eastern Pacific as a whole.

Material examined. Hydrolagus macrophthalmus: Museo Nacional de Historia Natural de Chile: M.NHNC.P 7282 (Holotype), male 385mmTL; M.NHNC.P 5724, male 445 mmTL and M.NHNC.P 6421(A), female 627 mmTL, Chile. CICIMAR–CI: 6370, male 945 mmTL, Manzanillo (Mexico). Hokkaido University Museum of Zoology: HUMZ 167128, male 612 mmTL, HUMZ 167443, female 636 mmTL, HUMZ 167820, female 594 mmTL, HUMZ 167821, female 515 mmTL,; HUMZ 173320, female 540 mmTL; HUMZ 185708, female 560 mmTL, and HUMZ 185709, male 527 mmTL (Peru).

We thank the fishermen of Manzanillo, Colima (México) for the donation of the specimen. Also, to the Centro Regional de Investigaciones Pesqueras (CRIP–Manzanillo) for preserving the specimen, as well as to D.A. Ebert (CSU–MLML) for his helpful comments on the identity of the specimen and D. Catania (CAS), and J. Maclaine (BMNH) for lending pictures for comparison. This research was partially supported by COFAA, EDI–IPN and SNI–CONACYT grants. I Fogel edited the text.

Literature cited

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Note

After this report was accepted for publication, a paper by James et al. (2009) describing a new Hydrolagus (H. melanophasma) was published. This new species, as far as known, is distributed off both coast of Baja California peninsula, also in very deep water. So, in the eastern Pacifi c, until now, there are 5 chimaerid described species. [James, K.C., D.A. Ebert., D.J. Long and D.A.Didier. 2009. A new species of chimaera, Hydrolagus melanophasma sp. nov. (Chondrichthyes: Chimaeriformes: Chimaeridae), from the eastern north Pacifi c. Zootaxa 2218:59–68].