Balaenophilus manatorum (Ortíz, Lalana and Torres, 1992)

Suárez-Morales, Eduardo, Morales-Vela, Benjamín, Padilla-Saldívar, Janneth & Silva-Briano, Marcelo, 2010, The copepod Balaenophilus manatorum (Ortíz, Lalana and Torres, 1992) (Harpacticoida), an epibiont of the Caribbean manatee, Journal of Natural History 44 (13 - 14), pp. 847-859 : 848-853

Balaenophilus manatorum (Ortíz, Lalana and Torres, 1992)

( Figures 2–4 )

Material examined

Five adult females, three adult males from a male T. manatus manatus (BCH 49) sampled by Marco Benítez and Janneth Padilla on 22 March 2007 from Chetumal Bay, Quintana Roo, Mexico (ECO-CHZ-05296) . Three adult females, three adult males from a female T. manatus (BCH 40) sampled 11 October 2006 from Chetumal Bay , Quintana Roo, Mexico (ECO-CHZ-05297) . Two adult females, four adult males from a female T. manatus (BCH 42) sampled 13 October 2006 from Chetumal Bay , Quintana Roo, Mexico (ECO-CHZ-05298) . Two adult females, two adult males from a female T. manatus (BCH 42), same locality, date and collectors, processed for SEM, specimens at the Universidad de Aguascalientes, Mexico . Six adult females, three ovigerous females, three adult males from the olive ridley turtle Lepidochelys olivacea , sampled on 2 August 2002 from unknown beach south of Chamela , Jalisco, Mexico (19°28′ N, 105°03′ W) , coll. A. Peña de Niz, specimens undissected (ECO- CHZ-03574). Two adult females, one adult male from L. olivacea , same locality, date and collector, processed for SEM, specimens at the Universidad de Aguascalientes, Mexico .

Remarks

Morphology. The general morphology of the specimens collected from the Caribbean manatee is as described by Ogawa et al. (1997) from Japanese specimens collected from sea turtles and by Suárez-Morales and Laso-Wasem (2009) from specimens collected in the Mexican Pacific. The average size of the female specimens from the Caribbean manatee (0.95 mm, range 0. 92–1.05 mm, n = 30) is slightly lower than the size reported by Ortíz et al. (1992) from the type locality (1.1 mm) from a manatee, Ogawa et al. (1997) from sea turtles in Japanese waters (1.24 mm, range 1.14–1.32 mm), and Suárez-Morales and Laso-Wasem (2009) from sea turtles of the Mexican Pacific (1.11 mm, range 1.03–1.14 mm). Males were also slightly smaller (average 1.01 mm, n = 10) than in the other groups ( Japan 1.14 mm, Cuba 1.2 mm, Mexican Pacific 1.18 mm) ( Ortíz et al. 1992; Ogawa et al. 1997; Suárez-Morales and Laso- Wasem 2009).We found no differences in the body proportions or appendages of both groups of specimens from Mexico after the SEM-based comparison of specimens collected from sea turtles (Mexican Pacific) and those obtained from the Caribbean manatee (Mexican Atlantic). This analysis included the main taxonomic characters of the species, such as the structure of the first leg distal endopodal and exopodal segments armed with three claws (see Figures 2D , 3E , 4B,D,E ), the relatively short caudal rami in both sexes ( Figure 2C,F ), the cuticular ornamentation of the thoracic somites ( Figures 3E , 4A,C ) and urosomal somites ( Figures 2C,F , 4A ) in both males and females, and the structure of the maxillipeds ( Figures 2B,D,E , 3D ) and the antennae ( Figures 2E , 3A,B ).

Manatee infestation with Balaenophilus . Of 54 manatees examined, 14 (25.9%, six males, eight females) were infested by B. manatorum ; of these, incidence was highest in young adult females (five individuals infested), followed by young adult males (four individuals). Copepods were also present on adult males and females, but not on juvenile individuals (see Table 1). Of the two localities in which manatees were examined, B. manatorum was recorded only from individuals captured in Chetumal Bay.

Balaenophilus as an epibiont. It is possible to observe patches of B. manatorum while the manatee is in the water; they are visible as ochre-coloured areas with the shape of the skin folds and wrinkles ( Figure 5B ). These patches are also conspicuous when the manatee skin starts to dry out, during the tagging process ( Figure 5A,C,D ). Harpacticoids were found clustered forming a granulose, soft mass loosely adhered to the skin of the manatee. The patches were of different sizes and densities, but were always associated with and longitudinally arranged along skin folds. Copepods were found directly attached to the skin, probably clinging to the smaller crevices and ridges of the irregular skin surface. All patches of B. manatorum were related to body areas of the manatee with long, relatively deep skin folds, including the area around the muzzle ( Figure 5A ), the bases of pectoral fins ( Figure 5B,C ), the area around the nipples ( Figure 5D ) and the base of the caudal fin, but not in the relatively exposed body depressions. Clusters of B. manatorum were not observed around the anus or the genitalia ( Figure 6 ). When the patches were removed from the skin, there was no visible effect of the presence of the colonies of B. manatorum on the manatee. Clusters of this copepod were not related to groups of barnacles or algal patches.

Figures

Figure 2. Morphology of Balaenophilus manatorum from the skin of Trichechus manatus in the Caribbean coasts of Mexico. (A) Cephalic area of adult female, lateral view; (B) maxilliped of female, lateral view; (C) last urosomites of adult female showing cuticular ornamentation; (D) maxilliped, first and second legs of female specimen, lateral view; (E) habitus of male, semiventral view; (F) caudal rami of adult female, ventral view showing ornamentation of anal somite and caudal rami.

Figure 3. Morphology of Balaenophilus manatorum from the carapace of the sea turtle Lepidochelys olivacea from the coasts of Jalisco, Mexican Pacific. (A) Adult male, lateral view; (B) antennule of female specimen; (C) cephalic area of adult female, lateral view; (D) maxilliped of adult female; (E) maxilliped and legs 1–4 of female, lateral view.

Figure 4. Morphology of Balaenophilus manatorum from the skin of Trichechus manatus in the Caribbean coasts of Mexico and from the sea turtle Lepidochelys olivacea from the Mexican Pacific. (A) Maxilliped and legs 1–4 of adult male from the manatee; (B) distal claws of endopod of first legs of female from manatee; (C) ovigerous adult female from the manatee; (D) distal claws of endopod of first legs from the sea turtle; (E) first legs showing long endopod and short exopod. Some patches in (A) also shown in (D). Scale bar = 0.5 m.

Figure 5. Sites of infestation of Balaenophilus manatorum on the Caribbean manatee from Chetumal Bay, Mexico, photographs from different individuals. (A) Muzzle skin folds and wrinkles; (B) base of the pectoral fin, specimen photographed under the water, note yellowish patch along skin fold; (C) base of the pectoral fin, patch outside the water; (D) wrinkled surface around a nipple.

Figure 6. Generalized overview of the sites of infestation of Balaenophilus manatorum on the Caribbean manatee from Chetumal Bay, Mexico. Infestation indicated by shadowed areas of the body.