Phylogenetics of Bonamia parasites based on small subunit and internal transcribed spacer region ribosomal DNA sequence data

Abstract

The genus Bonamia (Haplosporidia) includes economically significant oyster parasites. Described species were thought to have fairly circumscribed host and geographic ranges: B. ostreae infecting Ostrea edulis in Europe and North America, B. exitiosa infecting O. chilensis in New Zealand, and B. roughleyi infecting Saccostrea glomerata in Australia. The discovery of B. exitiosa-like parasites in new locations and the observation of a novel species, B. perspora, in noncommercial O. stentina altered this perception and prompted our wider evaluation of the global diversity of Bonamia parasites. Samples of 13 oyster species from 21 locations were screened for Bonamia spp. by PCR, and small subunit and internal transcribed spacer regions of Bonamia sp. ribosomal DNA were sequenced from PCR-positive individuals. Infections were confirmed histologically. Phylogenetic analyses using parsimony and Bayesian methods revealed one species, B. exitiosa, to be widely distributed, infecting 7 oyster species from Australia, New Zealand, Argentina, eastern and western USA, and Tunisia. More limited host and geographic distributions of B. ostreae and B. perspora were confirmed, but nothing genetically identifiable as B. roughleyi was found in Australia or elsewhere. Newly discovered diversity included a Bonamia sp.

Bonamia in Ostrea angasi: Diagnostic performance, field prevalence and intensity

“…Differences in Bonamia prevalence and intensity between farms in SA may be associated with lower oyster density and proximity (Arzul & Carnegie, ; Lallias et al., ) of O. angasi and C. gigas in Streaky Bay (16 leases) than in Coffin Bay (141 leases) (PIRSA, ). Given that C. gigas is probably a host of Bonamia (see Hill et al., ; Lynch et al., ), large populations of Pacific oysters may be important reservoirs of Bonamia in the environment. No Bonamia was detected in O. angasi spat (via histology or qPCR) from the hatchery site, despite broodstock having been sourced from infected areas.…”

Bonamia ostreae in the New Zealand oyster Ostrea chilensis: a new host and geographic record for this haplosporidian parasite

“…A further possible host for B. exitiosa in New Zealand is Ostreola stentina from the Hauraki Gulf. DNA sequences matching B. exitiosa were reported from Hill et al (2014), although this was not corroborated by other methods such as histology or in situ hybridisation (ISH).…”

“…All experiments included a noprobe control (25 µl of hybridisation buffer only), a negative control (Crassostrea gigas), and the experimental sample. Tissue sections were processed for ISH as described by Stokes & Burreson (1995) including the modifications made by Hill et al (2014). Cover-slipped ISH slides were examined under an Olympus BX51 light microscope.…”

“…Its type-host (Hine et al 2001) is the New Zealand dredge, or flat oyster Ostrea (= Tiostrea) chilensis (= lutaria), a significant customary, recreational and commercial species predominantly exploited in the Foveaux Strait (Ministry for Primary Industries 2014). It is important to note that Hill et al (2014) incorrectly reported B. ostreae in the European flat oyster Ostrea edulis from New Zealand, when in fact it was reported in O. edulis from the Netherlands (R. Carnegie pers. comm.…”

Microbial Diseases of Bivalve Mollusks: Infections, Immunology and Antimicrobial Defense

“…B. exitiosa was found in O. chilensis in South Island, New Zealand [47] , and in Ostrea angasi in southeastern Australia [48]. Since 2003, the parasite has been observed in both the Atlantic and Pacific coasts of the USA [49], including California [50]; B. exitiosa was also detected in O. edulis from the Galician coast (Spain) and the Manfredonia Gulf, Italy (Adriatic Sea), including concurrent infections with B. ostreae [51] and in Ostrea stentina in Tunisia [52]. B. exitiosa was found, as well, on the Spanish Mediterranean coast [53], in southwestern England [54] and in southern Portugal [55].…”