On the Occurrence of Conchoderma Virgatum and Dosima Fascicularis (Cirripedia, Thoracica) on the Sea Snake, Pelamis Platurus (Reptilia, Serpentes) in Jalisco, Mexico
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ON THE OCCURRENCE OF CONCHODERMA VIRGATUM AND DOSIMA FASCICULARIS (CIRRIPEDIA, THORACICA) ON THE SEA SNAKE, PELAMIS PLATURUS (REPTILIA, SERPENTES) IN JALISCO, MEXICO BY FERNANDO ALVAREZ and ANTONIO CELIS Colección Nacional de Crustáceos, Instituto de Biología, Universidad Nacional Autónoma de México, Apartado Postal 70-153, Mexico 04510, D.F., Mexico In May 2000, a mature, yellow-bellied sea snake, Pelamis platurus (Lin- naeus, 1766) (61 cm total length), was collected on Chamela Beach (19◦3153N 105◦535W), Jalisco, Mexico. Attached at two sites on the posterior portion of the snake were two barnacle aggregations consisting of two species, Conchoderma virgatum (Spengler, 1790) and Dosima fascicularis (Ellis & Solander, 1786). Pelamis platurus exhibits a widespread distribution in tropical waters, from the east coast of Africa, through the Indo-Pacific, to the Pacific coast of the Americas (Casas, 1997). In Mexican waters, it can be very abundant along the slicks, drift lines that form 5 to 10 km from the coast, and it is occasionally washed ashore during storms or strong winds (Casas, 1997). Although barnacles have previously been reported to occur on other sea snakes (Jeffries & Voris, 1979; Yamato et al., 1996), no such records exist for P. platurus along the coasts of Mexico. The lepadomorph, Conchoderma virgatum is a cosmopolitan species occurring in tropical and temperate waters. This species has been found attached to a wide variety of animal life and other objects (Harper, 1995). At shallow depths (<50 m), C. virgatum is an important fouling species that can rapidly get established, producing high biomass and abundance. In the Mexican Pacific, it has been recorded from La Gloria, Jalisco, on the turtle, Lepidochelys olivacea (Eschscholtz, 1829) (cf. Hernández & Valadéz, 1998). The pelagic Dosima fascicularis is an abundant species in the temperate waters of both hemispheres. It is a fugitive species, characterized by a rapid colonization of bare substrates, it can reproduce after only 45 days following settlement, and it is frequently overgrown by other fouling organisms as succession proceeds, including other barnacles (Blankley, 1985). No previous records of this species in Mexican waters exist. © Koninklijke Brill NV, Leiden, 2004 Crustaceana 77 (6): 761-764 Also available online: www.brill.nl 762 NOTES AND NEWS Fig. 1. The sea snake, Pelamis platurus (L., 1766) with barnacle clusters on the tail consisting of Conchoderma virgatum (Spengler, 1790) and Dosima fascicularis (Ellis & Solander, 1786). The single P. platurus collected had 63 barnacles, 61 C. virgatum and 2 D. fas- cicularis, forming two clusters (fig. 1). The sea snake with the barnacles is deposited in the Colección Nacional de Crustáceos (CNCR), Instituto de Biología, Universidad Nacional Autónoma de México, with catalogue number CNCR 21022. The two attachment sites were tearing off the delicate skin of the snake. Only two cypris larvae were found. The average capitulum length of C. virgatum was 11.3 mm (range 1.5-20 mm), while the two D. fascicularis measured 4.1 and 3.7 mm, respectively. This occurrence pattern is consistent with the strategies used by the two barnacle species, suggesting that D. fascicularis got established first and was later excluded by C. virgatum. However, the distribution of D. fascicularis in waters off the coast of North America indicates that it is abundant down to southern California, and rare or absent in warmer waters to the south. Its presence off the coasts of Jalisco, where superficial water temperature is above 25◦C, may be the result of a latitudinal migration of the snake. Of the 61 C. virgatum, 27 (44%) were gravid (fig. 2). The mean capitulum length of gravid individuals was 15.8 ± 2.2 mm (range 11.7-20 mm). Eckert & Eckert (1987) reported for C. virgatum, collected from the turtle Dermochelys.