Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, Porto, Portugal.
Instituto de Investigação e Inovação em Saúde (i3S), University of Porto, Porto, Portugal.
PeerJ. 2023 Jan 13;11:e14599. doi: 10.7717/peerj.14599. eCollection 2023.
Myxosporeans are widespread cnidarian parasites that usually parasitize fish as part of their complex life cycle, thus constituting a potential threat for the aquaculture industry. White seabream (L.) is a commercially valuable sparid fish reared in Southern European aquacultures. Nonetheless, knowledge on myxosporean infections potentially harming the sustainable production of this fish is extremely limited. In this study, a myxosporean survey was conducted on specimens reared in two Southern Portuguese fish farms. Two coelozoic myxosporeans were detected infecting the gall bladder, and are herein reported based on microscopic and molecular procedures: n. sp. and Rocha et al., 2013, previously described from reared stocks of gilthead seabream in the same geographic locality. n. sp. is the 12 species of the genus to be reported from Southern European sparids, reinforcing a substantial radiation of within this fish family and geographic region. SSU rRNA-based Bayesian inference and maximum likelihood analyses revealed n. sp. positioned separately from other sparid-infecting spp. reported from Southern European countries, demonstrating that this species does not share a more immediate common ancestor with its closest relatives based on host affinity and geography. The recognition of a novel sparid-infecting lineage within the clade strengthens the contention that this genus entered sparid fish multiple times, namely in the Southern European region. The identification of infections in demonstrates that host shift has occurred among sparids reared in the Southern Portuguese coast. This agrees with the broad host specificity that is usually attributed to this genus, and that may be suggested to be the outcome of the capacity of the morphotype to undergo host shift/switch based on our findings and the limited molecular data available for this genus. Thus, a better understanding of host-associated diversification and dispersal mechanisms requires the increasing availability of molecular data from infections of the same species occurring in multiple hosts and geographical locations.
粘孢子虫是广泛存在的刺胞动物寄生虫，通常作为其复杂生活史的一部分寄生在鱼类身上，因此对水产养殖业构成了潜在威胁。白鲷（L.）是一种商业价值很高的 Sparidae 鱼类，在南欧水产养殖中养殖。尽管如此，关于可能危害这种鱼类可持续生产的粘孢子虫感染的知识极其有限。在这项研究中，对两个葡萄牙南部鱼类养殖场饲养的标本进行了粘孢子虫调查。在胆囊中检测到两种腔生粘孢子虫感染，根据微观和分子程序进行了报道：n. sp. 和 Rocha 等人，2013 年，以前从同一地理区域养殖的金头鲷中描述过。n. sp. 是从南欧 Sparidae 鱼类中报告的第 12 种物种，这加强了在该鱼类家族和地理区域内的大量辐射。基于 SSU rRNA 的贝叶斯推断和最大似然分析表明，n. sp. 与从南欧国家报告的其他 Sparid 感染的 spp. 分开定位，表明该物种与其最近的亲缘关系没有基于宿主亲和力和地理的更直接的共同祖先。在 分支内发现的新 Sparid 感染谱系加强了这样的论点，即该属已多次进入 Sparid 鱼类，即在南欧地区。在 中鉴定出的感染表明，在葡萄牙南部海岸饲养的 Sparid 中发生了宿主转移。这与通常归因于该属的广泛宿主特异性一致，并且根据我们的发现和该属可用的有限分子数据，这种宿主特异性可能是由于 形态发生宿主转移/切换的能力所致。因此，需要越来越多的来自同一物种在多个宿主和地理位置发生的感染的分子数据，以更好地了解 宿主相关的多样化和传播机制。
