A NEW OPECOELID SPECIES (TREMATODA: OPECOELIDAE) FROM THE THREESPINE STICKLEBACK GASTEROSTEUS ACULEATUS L. IN CALIFORNIA

Plagioporus kolipinskii n. sp. (Trematoda: Opecoelidae) is described from the intestine of the threespine stickleback. Gasterosteus aculeatus L.. from Lobos Creek, a freshwater stream in Presidio, San Francisco County,. California Plagioporus kolipinskii is morphologically somewhat similar to 4 (P. serotinus Stafford, 1904. P. (angusticollis Hausmann. 1896, P. macrouterinus Haderlie, 1953, and P. shawi [McIntosh, 1939]) of the 12 Currently recognized North American species of the genus, but call be readily distinguished from all 4 in possessing a much larger acetabulum and a larger ovary relative to the testes. In addition, the new species can be distinguished front P. angusticollis by a smaller cirrus Sac: from P. macrouterinus by the elongated shape of its body and reduced extent of its uterus (the uterus of P. macrouterinus extends posteriorly to the intersection of the testes); from P. shawi by a much-shorter cirrus sac (which reaches the ovary in P. shawi), all unlobed ovary (as Opposed to a quadrilobed ovary in P. shawi), and fewer eggs that are also larger relative to body size.