New Information on the Cranial Anatomy of Acrocanthosaurus atokensis and Its Implications for the Phylogeny of Allosauroidea (Dinosauria: Theropoda)

Allosauroidea has a contentious taxonomic and systematic history. Within this group of theropod dinosaurs, considerable debate has surrounded the phylogenetic position of the large-bodied allosauroid Acrocanthosaurus atokensis from the Lower Cretaceous Antlers Formation of North America. Several prior analyses recover Acrocanthosaurus atokensis as sister taxon to the smaller-bodied Allosaurus fragilis known from North America and Europe, and others nest Acrocanthosaurus atokensis within Carcharodontosauridae, a large-bodied group of allosauroids that attained a cosmopolitan distribution during the Early Cretaceous.Re-evaluation of a well-preserved skull of Acrocanthosaurus atokensis (NCSM 14345) provides new information regarding the palatal complex and inner surfaces of the skull and mandible. Previously inaccessible internal views and articular surfaces of nearly every element of the skull are described. Twenty-four new morphological characters are identified as variable in Allosauroidea, combined with 153 previously published characters, and evaluated for eighteen terminal taxa. Systematic analysis of this dataset recovers a single most parsimonious topology placing Acrocanthosaurus atokensis as a member of Allosauroidea, in agreement with several recent analyses that nest the taxon well within Carcharodontosauridae.A revised diagnosis of Acrocanthosaurus atokensis finds that the species is distinguished by four primary characters, including: presence of a knob on the lateral surangular shelf; enlarged posterior surangular foramen; supraoccipital protruding as a double-boss posterior to the nuchal crest; and pneumatic recess within the medial surface of the quadrate. Furthermore, the recovered phylogeny more closely agrees with the stratigraphic record than hypotheses that place Acrocanthosaurus atokensis as more closely related to Allosaurus fragilis. Fitch optimization of body size is also more consistent with the placement of Acrocanthosaurus atokensis within a clade of larger carcharodontosaurid taxa than with smaller-bodied taxa near the base of Allosauroidea. This placement of Acrocanthosaurus atokensis supports previous hypotheses of a global carcharodontosaurid radiation during the Early Cretaceous

A new microsporidian parasite of the genus Amblyospora (Hazard and Oldacre, 1975) identified from the halophilic mosquito Ochlerotatus detritus (Haliday, 1833) (Diptera: Culicidae) through rDNA ITS sequencing

Ochlerotatus detritus (Haliday, 1833) from Parkgate marshes, Wirral, UK are shown to be parasitised by a new species of Amblyospora (Hazard and Oldacre, 1975) microsporidian. Phylogenetic analysis shows that Internal Transcribed Spacer sequences from this microsporidian are distinct from those of all known microsporidia identified to date, but form a clade with Amblyospora weiseri Lukeš and Vávra, 1990 and A. stictici Andreadis, 1994, microsporidia identified from Ochlerotatus cantans Meigen, 1818 and O. sticticus Meigen, 1838, respectively. Prevalence rates, from pooled samples (N = 5 per pool) were low (2.37%; lower limit 0.78%, upper limit 5.62%), which may be a consequence of these ephemeral brackish water pool habitats periodically drying out. There is increasing interest in the use of microsporidian parasites as novel vector control strategies and understanding the phenology of this microsporidian and its mosquito host may ultimately lead to new methods of control for this nuisance biting species