First Record of the American Alligator (Alligator mississippiensis) as a Host to the Sea Turtle Barnacle (Chelonibia testudinaria)

Chelonibia testudinaria (Sea Turtle Barnacle) and other closely related barnacle species of the genus Chelonibia are known to utilize a variety of organisms for their attachment substrate. These include the calcifi ed exoskeleton of marine crustaceans and chelicerids, the epidermis of manatees, and the carapace regions of all extant sea turtle species. Here, we present the fi rst records of an Alligator mississippiensis (American Alligator; Alligatoridae) as a host for C. testudinaria. Introduction. The 23 extant species of crocodilians, including Alligator mississippiensis Daudin (American Alligator), are known to serve as hosts to a variety of parasitic organisms. These include endo-parasites such as blood helminths, pentastomids, and nematode worms (Junker and Boomker 2006, Moravec 2001, Riley and Huchzermeyer 2000) and ecto-parasites such as leeches and ticks (Monroe and Garret 1979, Rainwater et al. 2001). While endo-parasites are more prevalent by frequency of occurrence and total parasitic biomass (Gabrey et al. 2008), high concentrations of ecto-parasites can occur and potentially cause detrimental impacts to the health of an individual. For example, ticks and leeches are reported to attach to the surface of crocodilian eyes, nictitating membranes, ear-drum/ear-opening, cloaca, and soft portions of the epidermis, causing damage to blood capillaries and soft tissues, and potentially harboring bacteria/ viral infections (Rainwater et al. 2001). A number of ecto-parasites are reported to occur on American Alligators, the most frequently encountered are various species of freshwater leeches (Class: Hirudinea), usually found attached to portions of the skin between hardened scutes and other soft tissues of the mouth, ear openings, cloaca, and eyes. A few observations of ticks attaching to soft tissues under the ear flap (Kent Vliet, University of Florida, Department of Biology, Gainesville, FL, pers. comm.) have been made, but ticks do not seem to be prevalent ecto-parasites in wild populations of crocodilians (Rainwater et al. 2001). Conversely, the occurrence of non-parasitic, commensal epi-bionts other than various aquatic plants and algae is rare. To our knowledge, the only previous record of a crocodilian hosting a non-plant commensal epi-biont is of two Chelonibia testudinaria L. (Sea Turtle Barnacle) from a single Crocodylus porosus Schnieder (Estuarine Crocodile) inhabiting coastal northern Australia (Monroe and Garret 1979). Here, we present novel observations of C. testudinaria (Subphylum: Crustacea, Class: Maxillopoda), utilizing American Alligators as a host in a coastal estuary of northeastern Florida. In addition, this epi-biont is the first organism to successfully utilize the hardened keratinized portions of scute tissue and/or osteoderms of American Alligators for an attachment substratum. Observations. During night-time captures on 16 June 2010 at 2320 within Guana Lake, an estuarine impoundment located within the Guana River Wildlife Management Area, Ponte Vedra, FL (N 30.07052, W -81.34116), a large adult male American Alligator (tail tag: GTM 125, total length [TL]: 292.5 cm, snout-to-vent length [SVL]: University of Florida, Department of Biology, PO Box 118525, Gainesville, FL 32611. Friends of the National Zoo, Smithsonian National Zoological Park, PO Box 37012, MRC 5516, Washington, DC 20013-7012. *Corresponding author ncboy@ufl .edu. Notes of the Southeastern Nat u ral ist, Issue 10/3, 2011