A species pair of Bivesicula Yamaguti, 1934 (Trematoda: Bivesiculidae) in unrelated Great Barrier Reef fishes: implications for the basis of speciation in coral reef fish trematodes

Abstract

Combined morphological and molecular analysis shows that a species of Bivesicula Yamaguti, 1934 from four species of Apogonidae Günther [Nectamia fusca (Quoy & Gaimard), Ostorhinchus angustatus (Smith & Radcliffe), O. cookii (Macleay) and Taeniamia fucata (Cantor)] on the Great Barrier Reef is morphologically similar to, but clearly distinct from B. unexpecta Cribb, Bray & Barker, 1994 which infects a sympatric pomacentrid, Acanthochromis polyacanthus (Bleeker). Bivesicula neglecta n. sp. is proposed for the form from apogonids. Novel ITS2 rDNA sequences generated for the two species differ at just one consistent base position, implying that the two species are closely related. The combination of their close relationship, high but distinct specificity and co-occurrence suggests that speciation was driven by a recent host switching event enabled by similar dietary ecomorphology.

A world of taxonomic pain: cryptic species, inexplicable host-specificity, and host-induced morphological variation among species of Bivesicula Yamaguti, 1934 (Trematoda: Bivesiculidae) from Indo-Pacific Holocentridae, Muraenidae and Serranidae

“…Bivesicula neglecta and B. unexpecta are clearly morphologically distinct and infect fishes of separate families (Pomacentridae and Apogonidae) in sympatry. They differ at just one base position in the ITS2 rDNA alignment (Trieu et al, 2015) and three base positions of 28S rDNA (this study) but new data here shows that they differ at 35 base positions in the cox1 alignment. The case of the delineation of B. sheni n. sp.…”

“…The complete ITS2 rDNA region (with flanking 5.8S and 28S rDNA regions) was amplified using the primers 3S (5′-GGT ACC GGT GGA TCA CGT GGC TAG TG-3′; Morgan and Blair, 1995 ) and ITS2.2 (5′-CCT GGT TAG TTT CTT TTC CTC CGC-3′; Cribb et al ., 1998 ), the partial D1-D3 28S rDNA region using LSU5 (5′-TAG GTC GAC CCG CTG AAY TTA AGC A-3′; Littlewood, 1994 ), and 1500R (5′-GCT ATC CTG AGG GAA ACT TCG-3′; Snyder and Tkach, 2001 ), and the partial cox 1 mtDNA region using Dig_cox1Fa (5′-GCT ATC CTG AGG GAA ACT TCG-3′; Wee et al ., 2017 ) and Dig_cox1R (5′-TCN GGR TGH CCR AAR AAY CAA AA-3′; Wee et al ., 2017 ). In addition to the new Bivesicula specimens being studied, genetic data were also generated for three other species from archival samples, for comparative purposes: B. neglecta Trieu, Cutmore, Miller and Cribb, 2015 ( cox 1: OM456635; ITS2: OM523336; 28S: OM459986); B. unexpecta Cribb, Bray and Barker, 1994 ( cox 1: OM456679–80; ITS2: OM523355); and an undescribed species from Bali, Bivesicula sp. ( cox 1: OM456678; ITS2: OM523354).…”

“…ITS2 rDNA and cox 1 mtDNA sequence data generated during this study were each aligned with MUSCLE in MEGA 11 (Tamura et al ., 2021 ) using UPGMA clustering for iterations 1 and 2.ITS2 rDNA sequences generated during this study were aligned withrelevant sequences available on GenBank (KR092219–22, Trieu et al ., 2015 ). The ends of each ITS2 rDNA fragment were trimmed for a final dataset of 453 base positions.…”

“…These studies, especially the recognition of regional genetic variation, have crystallized problems on the basis of species recognition, leading Bray et al (2022) to propose objective criteria for recognition of trematode species over range in the light of molecular data. This approach is applied here to trematodes of the family Bivesiculidae Yamaguti, 1934, a group for which molecular approaches have been little used (Trieu et al, 2015;Atopkin et al, 2017) and not at all over range. The Bivesiculidae is a small family of exclusively fish parasites occurring in a wide range of marine fish families (Cribb, 2002).…”

Variation in the parasite communities of three co‐occurring herbivorous coral reef fishes

“…Conversely, parasites recorded to infect P. wardi ( Spirocamallanus sp., Lester & Sewell, 1989; Lepotrema sp., Bray & Cribb, 1998) and S. doliatus ( Phthinomita sp., Nolan & Cribb, 2006; Lepeophtheirus sp., Grutter, 1994) at other GBR locations were not recorded to infect these species within the present study at Orpheus Island. These apparent differences in the parasite communities of S. doliatus and P. wardi add to a growing body of research documenting geographic variation in the parasite communities of reef fish within the GBR (Cribb et al ., 2014; Grutter, 1994; Trieu et al ., 2015). Some parasite taxa appeared to be common across greater geographic distances, with several parasite families and genera found to infect S. doliatus across the Pacific Ocean ( e.g ., Gyliauchen sp.…”