Aetomylaeus

Abstract: Two new species of the cestode genus Caulobothrium, collected from the duckbill eagle ray, Aetomylaeus bovinus, off Senegal, are described. Although postulated as sister taxa in an earlier molecular phylogenetic analysis, Caulobothrium multispelaeum n. sp. and Caulobothrium katzi n. sp., respectively, are among the smallest and largest members of the genus. The smaller species is unique among its congeners in possessing unusual medial longitudinal grooves along the dorsal and ventral surfaces of its strobila that develop into a tandem series of elliptical apertures on the posterior proglottids. The inner surfaces of these apertures stained positively with McManus' periodic acid Schiff in a manner similar to that seen in members of the distantly related lecanicephalidean genus Elicilacunosus. The larger species differs from its congeners in size, number of proglottids, and arrangement of bothridial loculi. Both new species were found to possess a small apical sucker on the anterior margin of each of their bothridia. Scanning electron microscopy (SEM) and frontal sections of a bothridium of Caulobothrium tetrascaphium suggests that this species also bears an apical sucker. Examination of the hologenophore of the species provisionally referred to as Caulobothrium n. sp. 5 in the earlier molecular analysis indicates it is conspecific with the recently described Caulobothrium pedunculatum, which was also determined to possess bothridial apical suckers. This leads us to suspect that this feature may be found to occur in all members of the genus. SEM of specimens of Caulobothrium for the first time indicates their bothridial surfaces are covered with filitriches of various sizes but lack spinitriches; spinitriches were seen only on the cephalic peduncle of C. katzi n. sp. The geographic distribution and host associations of Caulobothrium are expanded to include data now available for all species. The diagnosis of the genus is revised to include all of this information.

Abstract: The lower Miocene Pirabas Formation in the North of Brazil was deposited under influence of the proto-Amazon River and is characterized by large changes in the ecological niches from the early Miocene onwards. To evaluate these ecological changes, the elasmobranch fauna of the fully marine, carbonate-rich beds was investigated. A diverse fauna with 24 taxa of sharks and rays was identified with the dominant groups being carcharhiniforms and myliobatiforms. This faunal composition is similar to other early Miocene assemblages from the proto-Carribbean bioprovince. However, the Pirabas Formation has unique features compared to the other localities; being the only Neogene fossil fish assemblage described from the Atlantic coast of Tropical Americas. Phosphate oxygen isotope composition of elasmobranch teeth served as proxies for paleotemperatures and paleoecology. The data are compatible with a predominantly tropical marine setting with recognized inshore and offshore habitats with some probable depth preferences (e.g., Aetomylaeus groups). Paleohabitat of taxa particularly found in the Neogene of the Americas (†Carcharhinus ackermannii, †Aetomylaeus cubensis) are estimated to have been principally coastal and shallow waters. Larger variation among the few analyzed modern selachians reflects a larger range for the isotopic composition of recent seawater compared to the early Miocene. This probably links to an increased influence of the Amazon River in the coastal regions during the Holocene.

Abstract: The generic arrangement of the eagle rays (Family Myliobatidae) is revised and the genus Pteromylaeus Garman, 1913 is placed into the synonymy of Aetomylaeus Garman, 1908. Definitions are provided for the three valid genera, Aetobatus, Aetomylaeus and Myliobatis, and nomenclatural issues are discussed. Aetobatus differs from the latter two genera in having: a deeply notched nasal curtain, both jaws with a single row of chevron-shaped teeth, broadly rounded pectoral-fin free rear tips, pectoral fins separate from rostral lobe and joining head at level of eye. Aetomylaeus differs from the other two genera in having: pectoral fins separate from rostral lobe and joining head below level of eye, and stinging spine absent or present (usually not well developed when present). Myliobatis differs from the other two genera in having the pectoral fins joined to the rostral lobe by a subocular ridge. A list of valid species is provided, including a list of junior synonyms. Myliobatis australis Macleay, 1881 from southern Australia is placed into the synonymy of the previously considered endemic New Zealand species, M. tenuicaudatus Hector, 1877.

Abstract: New lecanicephalidean cestodes inhabiting the spiral intestine were investigated in 4 of the 6 known species of eagle rays of the genus Aetomylaeus Garman. Hosts examined consisted of 5 specimens of Aetomylaeus vespertilio from northern Australia, 5 of Aetomylaeus maculatus from Borneo, 10 of Aetomylaeus nichofii sensu stricto from Borneo, and 7 of Aetomylaeus cf. nichofii 2 from northern Australia. As a result of these new collections, 3 new genera and 6 new species of lecanicephalideans are formally described. Aetomylaeus vespertilio hosted the new genera and species Collicocephalus baggioi n. gen., n. sp. and Rexapex nanus n. gen., n. sp., as well as Aberrapex weipaensis n. sp. Aetomylaeus maculatus and A. nichofii sensu stricto hosted 3 new species of the novel genus Elicilacunosus, with the former eagle ray hosting Elicilacunosus sarawakensis n. sp. and the latter hosting both Elicilacunosus dharmadii n. sp. and Elicilacunosus fahmii n. sp. No new lecanicephalideans were described from A. ...