Description

Remarks This material is very similar to Cracticotania fieldingi (Maplestone & Southwell, 1923), the only species know in the genus. Cracticotania fieldingi was described from Cracticus destructor (now C. torquatus, Artamidae) in Queensland and attributed to Monopylidum by Maplestone & Southwell (1923). It was later placed in a newly erected monotypic genus by Spasskii (1966) and transferred to the Metadilepididae by Kornyushin & Georgiev (1994). Our material fits the most recent generic diagnosis of these authors with the notable exception that only a very faint vaginal sphincter is visible. Besides this character, it differs from the single known species in the genus by a smaller number of rostellar hooks (52 – 61 vs about 80), a slightly fewer testes (12 – 18 vs 16 – 21) and the differently-shaped and shorter cirrus-sac (globular vs pipette-like and 90 – 118 vs 130). It should, however, be noted that we examined the type material of C. fieldingi and the measurements provided by Maplestone & Southwell (1923) do not fully correspond to our observations. Although only two slides, mostly with gravid proglottides, are available, we noted a somewhat longer cirrus-sac (up to 180) and fewer testes (12 – 15). This, however, does not prevent the unambiguous separation of our material from C. fieldingi and we place it in a new species which we name Cracticotaenia adelaidae sp. nov. The specimens found in Corcorax Lesson, 1831 fit the above description of Cracticotaenia adelaidae sp. nov. in Gymnorhina tibicen quite well for most metric and meristic characters that can be observed. The main observed differences are in slightly smaller suckers (123 – 147 vs 155 – 198) and possibly more rostellar hooks (62 – 66 vs 52 – 61), and the faint vaginal sphincter that could not be observed. Keeping in mind that these observations are based on a limited number of incomplete specimens, we consider for now that these small variations (which may be partially exaggerated due to the poor preservation state of our specimens) are likely to be intraspecific. Although both belonging to the Corvides (see Jønsson et al. 2016), the hosts of C. adelaidae sp. nov. are not closely related and belong to clades that have probably diverged some 20 to 30 Ma ago (Jønsson et al. 2016; Moyle et al. 2016). The Australian magpie (G. tibicen) and the white winged chough (C. melanorhamphos) have however similar diets and habitats (Russell et al. 2017) as well as overlapping ranges (hosts reported in this study were captured a mere 100 km apart). This relative phylogenetic proximity and quite similar ecology probably largely explain the hosting of shared parasites.

Common Names

Taxonomic Hierarchy

Kingdom: Animalia

Phylum: Platyhelminthes

Class: Cestoda

Order: Cyclophyllidea

Family: Metadilepididae

Genus: Cracticotaenia

Species: Cracticotaenia adelaidae Mariaux & Georgiev, 2018