The shell is medium-sized, oblong to ovate, having solid to thin valves, sculpture of collabral growth lines and a surface covered with a thick brown periostracum. Umbos of juveniles have v- to w-shaped sculpture, usually eroded in shells more than 30 mm long. The interior of valves is nacreous bluish to bronze to white, with copper blotches. The hinge has pseudocardinal teeth which are strongly grooved and serrated; lamellar teeth are usually smooth and blade-like. Anterior retractor muscle scars are deeply impressed. Posterior end of shell tends to be more rounded than W. inbisi and overall, shells of this species are more oblong and largerr than W. inbisi, but series of shells are needed to note differences. From Klunzinger et al. (2022), “Specimens of W. carteri are distinguished from other Australian Westralunio taxa by having shell series that are significantly larger and more elongated than Westralunio inbisi inbisi subsp. nov., but not different from Westralunio inbisi meridiemus subsp. nov. The species has 10 diagnostic nucleotides at COI (57 G, 117 T, 210 G, 249 T, 255 C, 345 G, 423 T, 447 T, 465 A, 499 T) and 13 at 16S (137 T, 155 C, 228 C, 229 T, 260 G, 290 A, 305 G, 307 T, 310 A, 311 C, 321 T, 330 A, 460 A), which differentiate it from its sister taxa, W. inbisi inbisi and W. inbisi meridiemus using ASAP and TCS species delimitation models.”
Anatomy: A supra-anal opening is absent. Larvae (glochidia) are brooded in the marsupia in the inner pair of demibranchs of ctenidia in females, inhalant and exhalant siphons are short but prominent and formed by the mantle edge which is open ventrally and fused posteriorly; inhalant siphon larger than exhalant and bears a variable number of prominent papillae and is heavily pigmented with black and orange blotches.
Westralunio carteri Iredale, 1934
Common name: Carter's freshwater mussel
Infraclass Heteroconchia
Cohort Palaeoheterodonta
Order Unionida
Superfamily Unionoidea
Family Hyriidae
Subfamily Velesunioninae
Genus Westralunio Iredale,1934 (Type species: Westralunio ambiguus carteri Iredale, 1934)
Original name: Westralunio ambiguus carteri Iredale, 1934. In Iredale, T. (1934). The freshwater mussels of Australia. Australian Zoologist 8: 57-78.
Type locality: Victoria Reservoir in the Darling Ranges,12 miles east of Perth, Western Australia.
Synonym: Centralhyria angasi subjecta Iredale, 1934; “Westralunio carteri” I Klunzinger et al., 2021; Benson et al., 2022.
The last major taxonomic revision of Australian freshwater mussels was by McMichael & Hiscock (1958). Based on the available molecular results, Walker et al. (2014) pointed out that a reassessment of Australian hyriids is needed.
Molecular species delimitation modelling by Klunzinger et al. (2021) and Benson et al. (2022) recovered three distinct Evolutionarily Significant Units (ESUs) as “Westralunio carteri” I, “Westralunio carteri” II and “Westralunio carteri” III. Klunzinger et al. (2022) combined genetic data with morphometrical shape and shell measurement indices to formally describe “Westralunio carteri” I as Westralunio carteri Iredale, 1934; “Westralunio carteri” II as Westralunio inbisi inbisi sp. nov. and “Westralunio carteri” III as Westralunio inbisi meridiemus sp. nov.
The species is listed as VU – vulnerable on the IUCN Red List of Threatened Species, under the Commonwealth of Australia Environment Protection & Biodiversity Conservation Act 1999 and the Western Australia Biodiversity Conservation Act 2016.
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Mainly live in flowing freshwater rivers, streams and water supply reservoirs. Infaunal, living two thirds to almost fully buried in sand and sediment. Shallow burrower in silty sand/mud in streams and rivers. Suspension feeder. Dioecious. Females brood larva (glochidia) in marsupia in the inner pair of demibranchs. When released, glochidia become parasitic on fish gills or fins. After several weeks of undergoing metamorphosis on host fishes, glochidia become young mussels with a ciliated foot and two adductor muscles among other developments. They then detach from their host fish, dropping to the sediment to begin a suspension-feeding lifestyle.
Coastal rivers and streams of south-western Australia.
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