A new species of A new species of AcanthobothriumAcanthobothrium (Eucestoda: Onchobothriidae) (Eucestoda: Onchobothriidae) in in AetobatusAetobatus cf. cf. narinarinarinari (Myliobatidae) from Campeche, México = (Myliobatidae) from Campeche, México = (Eucestoda:

The helminthological examination of nine individuals of Aetobatus cf. narinari (spotted eagle ray; raya pinta; arraia pintada) revealed the presence of an undescribed species of cestode of the genus Acanthobothrium . The stingrays were collected from four locations in México: Laguna Términos, south of Isla del Carmen and the marine waters north of Isla del Carmen and Champotón, in the State of Campeche, and Isla Holbox, State of Quintana Roo. The new species, nominated Acanthobothrium marquesi , is a category 3 species (i.e, the strobila is long, has more than 50 proglottids, the numerous testicles greater than 80, and has asymmetrically-lobed ovaries); at the present, the only category 3 species that has been reported in the Western Atlantic Ocean is Acanthobothrium tortum . Acanthobothrium marquesi n. sp. can be distinguished from A. tortum by length (26.1 cm vs. 10.6 cm), greater number of proglottids (1,549 vs. 656), a larger scolex (707 µm long by 872 µm wide vs. 699 µm long by 665 µm wide), larger bothridia (626 µm long by 274 µm wide vs. 563 µm long by 238 µm wide). This is the first report of a species of Acanthobothrium from the Mexican coast of the Gulf México.

nine species, all from the Gulf of California ( Figure 1; Table 1). Only A. cartegenensis Brooks and Mayes, 1980 has been reported from the eastern coast of México (BROOKS & MAYES, 1980;MONKS et al., 2015). To date, no members of the genus have been reported from the Mexican coasts of Gulf of Mexico, but Linton (1908), Goldstein (1964), Goldstein et al. (1969) and Vardo-Zalik & Campbell (2011) collectively have reported nine species of Acanthobothrium from the northern coast of the Gulf of Mexico in waters of the USA. This suggests that members of the genus likely occur in more southern parts of the Gulf. As part of a parasitological survey of elasmobranchs in the Gulf of Mexico, adult cestodes were found in the spiral valve of Aetobatus cf. narinari (Euphrasen, 1790) that could be assigned to Acanthobothrium but not to any known species; this species is described herein. It represents the first record of the genus from the Mexican coast of the Gulf of Mexico.

Materials and Methods
From 1999 to 2005 the digestive tracts of nine stingrays, Aetobatus cf. narinari (Euphrasen, 1790) (spotted eagle ray; raya pinta; arraia pintada) were purchased from local fishermen at four localities: five rays from Isla del Carmen, Campeche (three from open water North of Ciudad del Carmen and two rays from Laguna de Términos) (18°36' N, 91°33' W and 18°37'58"N; 91°49'57"W, respectively) (2000 and 2005); three specimens from Champotón, Campeche, (19°21'N; 90°54'W) (1999); and one specimen from Holbox, Quintana Roo, northwest of the island, (21°34'N; 86°14'W) (2000) (Insets a and b in Figure 1, Table 2). Cestodes were removed from the spiral valve of the host, killed with hot tap water, transferred immediately to AFA (alcohol-formalin-acetic acid) for 24-48 hr, and then stored in 70°GL ethanol. Specimens were stained either with Mayer's carmalum or Ehrlich's hematoxylin and mounted in Canada balsam for examination as whole mounts; worms that were too large to be mounted on a single slide were cut into sections and mounted sequentially on separate slides. Stained specimens were examined using a compound photomicroscope equipped with Nomarski differential interference contrast optics (Leica DM LB2). Taxonomic information for the host was taken from McEachran & Dunn (1998), White et al. (2010), Richards et al. (2009), Froese & Pauly (2017. Some specimens were prepared for scanning electron microscopy (SEM) by dehydration in a graded ethanol series and low-vacuum dried. Dried specimens were mounted on aluminum stubs with carbon tape and  Table 1); a and b refers to the sampling areas reported in this study, where  is assigned to individuals of Aetobatus cf. narinari negative for A. marquesi n. sp. and  for individuals of Aetobatus cf. narinari that were positive for the new species. grounded with carbon paint before being sputter-coated with approximately 100 Å of gold/palladium (about two minutes). Specimens were examined using a Jeol JSM-6300 scanning electron microscope. Illustrations were made with the aid of a drawing tube. Measurements are in micrometers unless specified otherwise, and expressed as length by width. For most characters, ranges are given, followed in parentheses by the sample mean and sample size (n). Mean values ± 1 standard deviation is provided for some characters (i.e., mean ± sd; n = sample size). Hook measurements follow Euzet (1959) as modified by Monks et al. (1996) (i.e., mean value ± 1 standard deviation is given followed by, in parentheses, the range).
Specimens from three collections were examined: CNHE refers to the Colección Nacional de Helmintos, Instituto de Biología, Universidad Nacional Autónoma de México, Mexico City, México; CHE refers to the Colección de Helmintos, Centro de Investigaciones Biológicas, Universidad Autónoma del Estado de Hidalgo, Pachuca, México; and HWML refers to the Harold W.
9 *Reference number for locations on the map (see Figure 1).
Acanthobothrium cartagenensis Brooks and Mayes, 1980 is the only species that has been reported from the Eastern Coast of México (includes the Gulf of Mexico and Caribbean Sea). It can be distinguished from the new species because it is a Category 9 species (LFFS: L, >15 mm; F, ≤50 segments; F, ≤80 testes; S, left and right lobes symmetrical) (categories sensu GHOSHROY & CAIRA, 2001).
The new species is the third member of the genus reported from Aetobatus cf. narinari in the greater Atlantic Ocean. The species that have been reported from Aetobatus cf. narinari from the eastern Pacific Ocean are A. monksi Marques, Barriga, 1997, andA. nicoyaense Brooks andMcCorquodale, 1995 (both are Category 1 species; i.e., much smaller than the new species). None of these species have been reported from Mexican waters (MARGUEE et al., 1997;BROOKS & MCCORQUODALE, 1995). The species of Acanthobothrium that have been reported from Aetobatus cf. narinari from the western Atlantic Ocean are, A. colombianum Brooks and Mayes, 1980 and A. tortum (Linton, 1916) Baer and Euzet, 1962. Acanthobothrium marquesi is a Category 3 species (LMMA) (sensu GHOSHROY & CAIRA, 2001): total length > 15 mm (specimens of the new species are 26,100 mm long); number of proglottids > 50 (average of 1,549 proglottids); number of testes per proglottid > 80 (138 testes per proglottid); and ovarian lobes asymmetrical (aporal lobe reaches anteriorly from the posterior end of the proglottid to about the anterior margin of the cirrus sac and the poral lobe reaches anteriorly to the posterior margin of the cirrus sac).
Acanthobothrium tortum, as described by Campbell (1970)  Other amphi-American Category 3 species are A. holorhini Alexander, 1953 andA. maculatum Riser, 1955, both from Myliobatis californica Gill; neither has been reported from México. These two species are smaller than the new species in all structures and the number of testes is less in the former two species than in the new species. Finally, these two species and their hosts are known only from the Pacific coast.
The nominal species Aetobatus narinari (sensu Euphrasen) has classically been thought to be a globally-distributed species inhabiting tropical seas, but recent studies have suggested that it represents a species complex (RICHARDS et al., 2009;WHITE et al., 2010;WHITE et al., 2013), an hypothesis supported by parasitological studies (MARIE & JUSTINE, 2005;MARIE & JUSTINE, 2006). No molecular data exist for the particular populations of Aetobatus cf. narinari that are hosts to A. tortum and A. marquesi n. sp., but they are on the opposite north-south coasts of the Gulf of México; the presence of different species of Acanthobothrium in each suggests that these two population of Aetobatus cf. narinari do not mix. The study of divergence of cryptic populations of species that serve as hosts and that of their parasites is in initial processes, but studies of water currents in the Gulf of México/Caribbean Sea region suggest that more isolated species of helminths are waiting to be discovered (SHULMAN & BERMINGHAM, 1995;CARTON & CHAO, 1999;SANDOVAL-CASTILLO & ROCHA-OLIVARES, 2011).
Members of Aetobatus Blainville, 1816 traditionally have been considered to be part of Myliobatidae (FROESE & PAULY, 2017). However,  recently moved the genus to Aetobatidae. Although this arrangement has begun to be followed (LAST et al, 2016), we chose to follow the most widely accepted classification (FROESE & PAULY, 2017) pending further evaluations of the status of the family.