Title: ECHINOCEPHALUS JANZENI SP.N.(NEMATODA: GNATHOSTOMATIDAE) IN HIMANTURA PACIFICA (CHONDRICHTHYES: MYLIOBATIFORMES) FROM THE PACIFIC COAST OF COSTA RICA AND MEXICO WITH HISTORICAL BIOGEOGRAPHIC ANALYSIS OF THE GENUS
Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 30, 1997
Publication Date: N/A
Interpretive Summary: The biodiversity of marine parasites capable of infecting humans is still not well defined. Gnathostomatid nematodes have the potential to infect humans when raw or undercooked mollusks are consmed, as larvae of some species of the genus Echinocephalus are parasites of oysters and abalone. In this study we describe a previously unknown species of Echinocephalus. The nematode, E. janzeni, is a parasite in marine stingrays from Central America. Basic information on the comparative morphology and geographic distribution of the parasite are outlined. These are critical in providing information on the identification and diagnostics for species of Echinocephalus.
Echinocephalus janzeni sp n. in the stringray, Himantura pacifica, is described from the eastern Pacific Ocean off the coasts of Costa Rica and southern Mexico. Based on the presence of 6 postanal caudal papillae, and modified annules anterior to the caudal alae in males, E. janzeni is most similar to E. daileyi and E. diazi. Specimens of E. janzeni are distinguished from those of E. daileyi by bilobed caudal alae and long cervical sacs which extend up to 65% of the length of the esophagus; E. janzeni is differentiated from E. diazi by the number of rows of cephalic spines (30-38 versus 26-27), arrangement of the postanal caudal papillae, 3 rather than 2 preanal papillae, relative position and distance between the anus and vulva (395-460) #m). Cladistic analysis of the 10 Echinocephalus spp. places E. janzeni in a highly derived sub-clade where E. daileyi is the sister species of E. diazi + E. janzeni. Historical biogeographic analysis for hosts and parasites provides support for origins in the Pacific rather than the Atlantic for the potamotrygonid stringrays.