Nota

 

First record of Axiopsis serratifrons (A. Milne Edwards, 1873) (Crustacea: Decapoda: Thalassinidea) in western Mexico

 

Primer registro de Axiopsis serratifrons (A. Milne Edwards, 1873) (Crustacea: Decapoda: Thalassinidea) en México occidental

 

Michel E. Henrickx

 

Laboratorio de Invertebrados Bentónicos, Unidad Académica Mazatlán, UNAM, P.O. Box 811, Mazatlán, 82000, Sinaloa, México. E-mail: michel@mar.icmyl.unam.mx

 

Recibido: 23 de octubre de 2001
Aceptado: 23 de abril de 2002

 

Abstract

The thalassinid Axiopsis serratifrons (A. Milne Edwards, 1873) has been discovered in subtropical waters of the Gulf of California, Mexico, in the eastern Pacific. The large male specimen of this species, collected by scuba diving on rocky substrate represent the first record north of Colombia along the coast of the eastern Pacific. The material was compared to specimens from the Indo-Pacific and the morphology of its 4th and 5th thoracic sternites closely matches recent description by other authors.

Keywords: Axiopsis serratifrons, Axiidae, new record, Mexican Pacific.

 

Resumen

El talasinideo Axiopsis serratifrons (A. Milne Edwards, 1873) fue encontrado en las aguas subtropicales del golfo de California, México, en el Pacífico este. El espécimen, un macho de gran talla, fue recolectado por medio del buceo libre en fondos rocosos; se trata del primer registro de esta especie al norte del Pacífico colombiano. El material disponible fue comparado con especímenes del Indo-Pacífico y la morfología de las placas esternales 4 y 5 concuerda con su reciente descripción por otros autores.

Palabras clave: Axiopsis serratifrons, Axiidae, nuevo registro, Pacífico este.

 

Axiopsis serratifrons (A. Milne Edwards, 1873) was described from Hawaii and has since been reported for many localities in the Indo-Pacific (Sakai and de Saint Laurent, 1989). In 1980 it was also reported from several localities in the West Atlantic (Belize, Florida and Bermuda) (Kensley, 1980), where the species occurs abundantly in coral patches and under dead coral. This American material (including a large male of 62.0 mm TL and a large ovigerous female of 59.0 mm TL) was compared to a series of specimens from the Indo-Pacific kept in the United States National Museum (including a male of 35 mm TL and a female of 29.2 mm TL) and the species was redescribed.

In 1992, Axiopsis serratifrons was later reported from Gorgona Island, Pacific Colombia by Lemaitre and Ramos (1992), who also presented a rather complete illustration of this species and some remarks on its morphology, and from Ascension Island, Central Atlantic (Manning and Chace, 1990).

Since the discovery of A. serratifrons in the western Atlantic, the family Axiidae has been reviewed (Sakai and the Saint Laurent, 1989). An illustration and a description of the 4th and 5th thoracic sternites in A. serratifrons were provided, and were used as an important diagnostic characteristic at generic level.

The examination of a specimen of Axiidae received on loan from the Allan Hancok Foundation and its comparison with material from the Indo-Pacific previously cited in literature (Sakai and de Saint Laurent, 1989), and with the redescription of this species (Kensley, 1980; Lemaitre and Ramos, 1992) indicates that A. serratifrons is also present in the Mexican Pacific.

Abbreviations used are: TL, total length; CL, carapace length; LACMNH, Los Angeles Country Museum of Natural History; MNHP, Museum national d'Histoire naturelle, Paris.

Axiopsis serratifrons (A. Milne Edwards, 1873) Figs. 1, 2

Material examined.- El Bajo Sea Mount (25 nm NE of La Paz), Baja California, Mexico, 15/08/86, 1 male (TL 51.7 mm; CL 19.6 mm), 21 m, scuba diving, rocky substrate, A. Kerstitch (LACMNH C.R. 1986-705.1).

Aldabra, Seychelles Islands, 16/05/61, 1 female (TL 26 mm; CL 8 mm), 20 m, "Calypso", id. M. de Saint Laurent (MNHN Th 690).

Japan, 1977, 1 male (TL 36.9 mm; CL 11.2 mm), no depth recorded, Sakai; id. M. de Saint Laurent (MNHN Th 864).

Comments.- The specimen collected in the Gulf of California (El Bajo Sea Mount) is similar in size to the largest specimens reported from the eastern Atlantic by Kensley (1980) and slightly larger than the male reported from Ascension Island, Central Atlantic by Manning and Chace (1990). The colour of the freshly collected specimen was "dark maroon and white markings" (notes by A. Kerstitch), similar to the "chesnut-brown" colour of carapace with "pale blotchs and pale areas" reported for the male specimens collected in Belize and Bermuda (Kensley, 1980).

The eastern Pacific material reported here, share diagnostic characteristics with A. serratifrons, including: the typical dorsal armature of anterior carapace (carapace carinae spination, from left to right: 15, 13, 16 15 18) (Fig. 1B); the small ventrolateral marginal spine on pleura 3-6 (Fig. 1A); the shape and spination of the third maxilliped, including the presence of a row of about 20-23 spines on the inner surface of the ischium (Figs. 1J, 2H); the ventral spination on the merus and ischium of first and second pereiopods an the shape of the chelae (Fig. 1E, D); the spines pattern on the telson (Fig. 1C). All these characteristics, including the spination on the 3rd maxilliped (Fig. 2F, G) were observed on the specimen from Japan (MNHN Th 864) and are aso reported for the western Atlantic specimens (Kensley, 1980), although variations in the number of dorsal spines on carapace were observed among the Atlantic material. The structure of the grooming apparatus of pereiopod 5 also seems to be quite variable in A. serratifrons (Kensley, 1980); our specimens present a grooming structure similar to the Florida and Belize specimens previously reported (Kensley 1980) and features 11 small spines.

Perhaps the most striking feature of A. serratifrons is the structure of the 4th and 5th thoracic sternites, illustrated in 1989 and considered diagnostic (Sakai and de Saint Laurent, 1989) and which is closely matched in the Gulf of California specimen (Fig. 2I), except for the fact that the latter material presents a median notch on the 5th sternite (Fig. 2J).

The shape of the coxal plate of the 5th pereiopod seems to vary following a west-east gradiant; specimens from Gilbert Island (Fig. 2A) and from Japan (Fig. 2B) feature a ventral spine and a lobe, while the American material features two ventral spines (Fig. 2C-E), except for the male specimen reported by Manning and Chace (1990: fig. 17, c) from Ascension Island which also seems to present a sharp spine and a lobe on the ventral side of this coxal plate (although the illustration does not allow a very accurate comparison).

The proportions of the appendix masculina and the appendix interna of specimens from Belize and Floria (Kensley, 1980) and from the Gulf of California (0.7) (Fig. 2K) differ significantly from those of the Gilbert Island specimen (0.9), but the Bermuda specimen features a 0.6 ratio (Kensley 1980) and the Ascension specimen a 0.85 ratio (Manning and Chace 1990). Number of distal setae of the appendix masculina seems to vary considerably, from 6 to 10 (Kensley, 1980). The Gulf of California specimen features 7 setae (Fig. 2K).

While the large first chela of the Gulf of California specimen is only slightly longer (length/width 2.2) than western Atlantic specimens (length/width 1.6 to 2.1) (Kensley, 1980) the small chela is proportionally much longer (length/width 3.35 vs. 1.9 to 2.7). The proportion of the Central Atlantic male reported by Manning and Chace (1990: fig. 17) is strikingly different: large chela length/width 4.2; small chela length/width 4.8. But this migth be due to regeneration (Manning and Chace, 1990).

The author thanks M.K. Wicksten for calling his attention to the material examined. Fig. 1 is by Graciano Valenzuela and ms. edition by Mercedes Cordero.

 

References

Kensley, B., 1980. Notes on Axiopsis (Axiopsis) serratifrons (A. Milne Edwards, (Crustacea: Decapoda: Thalassinidea). Proceedings of the Biological Society of Washington 93 (4): 1253-1263.         [ Links ]

Lemaitre, R. & G. E. Ramos, 1992. A collection of Thalassinidea (Crustacea: Decapoda) from the Pacific Coast of Colombia, with description of a new species and a checklist of Eastern Pacific species. Proceedings of the Biological Society of Washington 105 (2): 343-358.         [ Links ]

Manning, R. B. & F. A. Chace Jr., 1990. Decapod and stomatopod crustacea from Ascension Island, South Atlantic Ocean. Smithsonian Contributions to Zoology 503: 1-82.         [ Links ]

Sakai, K. & M. de Saint Laurent, 1989. A checklist of Axiidae (Decapoda, Crustacea, Thalassinidea, Anomura), with remarks and in addition descriptions of one new subfamily, eleven new genera and two new species. Naturalists 3: 1-104.         [ Links ]