During an investigation of gill monogenoidean parasites from freshwater fishes in central Panama, 5 new species of Urocleidoides (sensu stricto) were found: Urocleidoides cultellus n. sp., Urocleidoides visiofortatus n. sp., and Urocleidoides advenai n. sp. from the gymnotiform Brachyhypopomus occidentalis (Hypopomidae); Urocleidoides neotropicalis n. sp. and Urocleidoides piriatiu n. sp. from the characiforms Saccodon dariensis (Parodontidae) and Ctenolucius beani (Ctenoluciidae), respectively. Our findings represent the first known species of Urocleidoides from these fishes in Central America and demonstrate that they are morphologically linked to their South American congeners.Urocleidoides Mizelle and Price 1964 (Monogenoidea: Dactylogyridae) (as amended by Kritsky et al., 1986), accommodates species possessing overlapping or tandem gonads, a coiled male copulatory organ with counterclockwise rings, a sinistral vaginal sclerite, unmodified anchors, and similar hooks with dilated shanks, and hooks pairs 1, 5, usually reduced in size. According to this diagnosis, 6 species of Urocleidoides {Uro-cleidoides anops Kritsky and Thatcher, 1974
MATERIALS AND METHODSFishes were collected with the use of electrofishing and trammel nets from Aguas Claras River at its confluence with the Bayano Lake (09°15'05.1"N, 78°41'11.2"W) and Rio Piriati River (09°03'36"N, 78°39'57"W) at its confluence with the Chagres River Basin in central Panama. Methods of collection, preparation of helminths for study, and measurement and illustration follow Mendoza-Franco et al. (2007). To study sclerotized structures, some specimens were mounted unstained in glycerin jelly. Measurements, all in micrometers (p,m), represent straight-line distances between extreme points and are expressed as the mean followed by the range and number (n) of structures measured in parentheses; body length includes the haptor. Numbering (distribution) of hook pairs follows Mizelle (1936; see Mizelle and Price, 1963) Diagnosis: Body fusiform 385 (165-712; n = 4) long, robust; greatest width 64 (41-76; n = 5) usually at level of testis. Cephalic margin broad; cephalic lobes moderately developed; 3 bilateral pairs of head organs; cephalic glands indistinct. Eyespots absent; accessory granules scattered in cephalic region and anterior trunk. Pharynx spherical 13 (12-18; n = 4) in diameter; esophagus moderately long. Peduncle broad; haptor subrectangular, 72 (65-85; n = 3). Ventral anchor 40 (39-43; n = 10) long, with elongate tapered superficial root, short deep root, proximally bent shaft, short point; base 23 (23-24; n = 5) wide. Dorsal anchor 24 (23-25; n = 7) long, poorly differentiated deep root, curved shaft, with bifurcate points; base 15 (15-16; n = 7) wide. Ventral bar 44 (42-47; n = 6) long, wide U-shaped with enlarged terminations; dorsal bar 37 (35-42; n = 4) long, with enlarged ends. Hooks similar, each with recurved point, depressed thumb, dilated shank; hook pairs 1, 5 reduced in size; filamentous booklet (FH) loop half shank length (pairs 1...