Five New Species of \u3ci\u3eAcanthobothrium\u3c/i\u3e Van Beneden, 1849 (Eucestoda: Tetraphyllidea: Onchobothriidae) in Stingrays from the Gulf of Nicoya, Costa Rica

Five new species of Acanthobothrium are described in stingrays from the Gulf of Nicoya, Costa Rica. Acanthobothrium costarricense n. sp. in Dasyatis longus, most similar to Acanthobothrium lilium, Acanthobothrium lineatum, and Acanthobothrium himanturi, has bothridial hooks averaging 125 μm (lateral) and 145 μm (medial) long, an average of 47 testes per proglottis, cirrus sacs averaging 187 μm long, and asymmetrical ovarian lobes with poral lobes reaching the posterior margin of the cirrus sac, and aporal lobes reaching the middle of the cirrus sac. Acanthobothrium cimari n. sp. in D. longus, most similar to A. lilium, A. lineatum, A. himanturi, A. costarricense, and Acanthobothrium semnovesiculum, has bothridial hooks averaging 117 μm (lateral) and 121 μm (medial) long, an average of 50 testes per proglottis, cirrus sacs averaging 164 μm long, and asymmetrical ovarian lobes with poral lobes reaching the posterior margin of the cirrus sac, and aporal lobes reaching the level of the vagina. Acanthobothrium puntarenasense n. sp. in D. longus, distinctive in having a very small scolex relative to the width of the cephalic peduncle similar to Acanthobothrium microcephalum, has bothridial hooks averaging 111 μm (lateral) and 117 μm (medial) long, an average of 50 testes per proglottis, cirrus sacs averaging 170 μm long, and asymmetrical ovarian lobes with poral lobes reaching the posterior margin of the cirrus sac, and aporal lobes reaching the middle of the cirrus sac. Acanthobothrium vargasi in D. longus, most similar to Acanthobothrium brevissime, Acanthobothrium tasajerasi, Acanthobothrium urotrygoni, and Acanthobothrium campbelli, has bothridial hooks averaging 130 μm (lateral) and 133 μm (medial) long, an average of 25 testes per proglottis arranged in two single rows, cirrus sacs averaging 91 μm long, and asymmetrical ovarian lobes with poral lobes reaching the posterior margin of the cirrus sac, and aporal lobes reaching the middle of the cirrus sac. Acanthobothrium campbelli n. sp. in Urotrygon chilensis, most similar to A. brevissime, A. vargasi, A. lineatum, A. himanturi, and A. urotrygoni, has bothridial hooks averaging 108 μm (lateral) and 111 μm (medial) long, an average of 19 testes per proglottis arranged in two nearly linear rows, cirrus sacs averaging 74 μm long, and asymmetrical ovarian lobes with the poral lobe reaching the posterior margin of the cirrus sac, and the aporal lobes reaching the middle of the cirrus sac