A Revision of Phoreiobothrium (Tetraphyllidea: Onchobothriidae) With Descriptions of Five New Species

Abstract

Five new species of Phoreiobothrium (Cestoda: Tetraphyllidea) are described from carcharhiniform sharks collected from a diversity of localities throughout the world. These are Phoreiobothrium perilocrocodilus n. sp. from Negaprion acutidens, Phoreiobothrium anticaporum n. sp. from Negaprion brevirostris, Phoreiobothrium lewinense n. sp. from Sphyrna lewini, Phoreiobothrium robertsoni n. sp. from Carcharhinus brachyurus, and Phoreiobothrium blissorum n. sp. from C. plumbeus, This brings the number of described species of Phoreiobothrium to 17. The new species from the lemon sharks, P. perilocrocodilus n. sp. and P. anticaporum n. sp., both possess more bothridial subloculi than do all species from hammerhead sharks, and fewer subloculi than do all species from sharks of Carcharhinus spp. Phoreiobothrium anticaporum n. sp. is unique among Phoreiobothrium species in that its genital pore is located in the extreme anterior portion of the proglottid. Phoreiobothrium lewinense n. sp. is unique in its possession of a combination of 8-11 subloculi and basal hook prongs that lack internal channels. Phoreiobothrium robertsoni n. sp. possesses 25-29 subloculi, triangular bothridia that flare posteriorly, and hooks that extend well beyond the middle of the bothridia. Phoreiobothrium blissorum n. sp. is most similar to Phoreiobothrium lasium in that it possesses rectangular bothridia with greater than 22 subloculi and long filitriches on its scolex. However, it differs from the latter species in that rather than articulating with one another, the bases of the medial and lateral hooks are widely separated; it also possesses 5-6 (vs.) 7-8 columns of testes. Phoreiobothrium lasium and Phoreiobothrium tiburonis are redescribed. The host associations of P. lasium are reevaluated and a neotype is designated for this species. The mature proglottid of P. tiburonis is described for the first time from voucher material collected from the type host and locality. These data suggest that the proglottid information provided in the original description, which was obtained from detached gravid proglottids, may have come from a tapeworm species other than P. tiburonis. All 7 species treated here in detail were examined with scanning electron microscopy; most were found to exhibit a microthrix pattern similar to that described previously for other members of the genus, e.g., Phoreiobothrium manirei. Bladelike spinitriches were present on the strobila, cephalic peduncle, and proximal bothridial surfaces, but were lacking from the distal bothridial surfaces. These spinitriches varied in length and density among species. Filitriches were present on all of these surfaces, but varied somewhat in length among species. Phoreiobothrium lewinense n. sp. is exceptional in that spinitriches were not seen on the proximal bothridial surfaces. A key to Phoreiobothrium species is provided. This work brings the number of carcharhinid shark species known to host this onchobothriid genus to 6, and the number of sphyrnid species to 5. Like many other onchobothr...

New and Emended Descriptions of Gregarines From Flour Beetles (Tribolium Spp. And Palorus Subdepressus: Coleoptera, Tenebrionidae)

“…For example, with the gregarine-flour beetle system, we can determine experimentally whether a parasite from 1 host species can, if given the opportunity, infect related hosts. Multispecies systems amenable to such experimental exploration of avenues for evolutionary change are not common, especially when one considers logistical constraints associated with the potential use of many reasonably well-studied taxa as laboratory models (e.g., see Snyder and Tkach, 2001;León-Règagnon and Brooks, 2003;Caira et al, 2005).…”

A revision of Megalonchos Baer & Euzet, 1962 (Tetraphyllidea: Onchobothriidae), with the description of two new species and transfer of two species to Biloculuncus Nasin, Caira & Euzet, 1997

“…Whereas the former three genera possess one pair of hooks per bothridium (e.g. see Southwell, 1925;Caira, Richmond & Swanson, 2005;Baer & Euzet, 1962, respectively), the latter two genera possess two pairs of hooks per bothridium (e.g. see Healy et al, 2001;Caira & Ruhnke, 1990, respectively); although the axial hook in each pair is bi-pronged in Erudituncus, it is uni-pronged in Biloculuncus.…”

Synergy advances parasite taxonomy and systematics: an example from elasmobranch tapeworms

“…On the other hand, species of individual tetraphyllidean genera, such as Phoreiobothrium , parasitize sharks of the more speciose families Carcharhinidae and Sphyrnidae (see Caira and Jensen, 2001; Caira et al . 2005 a ). Current estimates suggest that, in combination, these families include at least 63 species of sharks (Compagno, 2005).…”

“…Thus, it is fair to say that the total number of species in the order Litobothriidea is unlikely to exceed 28, and if our negative data are correct, the number is probably substantially lower. On the other hand, species of individual tetraphyllidean genera, such as Phoreiobothrium, parasitize sharks of the more speciose families Carcharhinidae and Sphyrnidae (see Caira et al 2005a). Current estimates suggest that, in combination, these families include at least 63 species of sharks (Compagno, 2005).…”

“…Once again, a number of these shark species have never been examined for cestodes; some have been examined and found to lack Phoreiobothrium (e.g. Curran and Caira, 1995); a number have been examined and found to be parasitized by one or even two members of this genus (see Caira et al 2005a andLinton, 1924, respectively). Thus, it is reasonable to predict that the total number of species of Phoreibothrium is unlikely to exceed 126 species and, if our negative data are correct, the number is again probably somewhat lower.…”