Marine Zoology Unit, Cavanilles Institute of Biodiversity and Evolutionary Biology, Science Park, University of Valencia, C/Catedrático José Beltrán 2, 46980, Paterna, Spain.
Parasit Vectors. 2020 Jan 31;13(1):45. doi: 10.1186/s13071-020-3878-9.
Microcotyle erythrini van Beneden & Hesse, 1863 (Platyhelminthes: Monogenea) and other closely related species of the genus are often considered as cryptic. Records in hosts other than the type-host with no species confirmation by molecular analyses have contributed to this situation.
Gill parasites of five sparid fishes, Boops boops (L.), Pagellus erythrinus (L.), P. acarne (Risso), Dentex dentex (L.) and Pagrus pagrus (L.), from the Western Mediterranean off Spain were collected. Specimens of Microcotyle spp. were characterised both molecularly and morphologically. Partial fragments (domains D1-D3) of the 28S rRNA gene and the cytochrome c oxidase subunit 1 (cox1) gene were amplified and used for molecular identification and phylogenetic reconstruction. Principal components analysis was used to look for patterns of morphological separation.
Molecular analyses confirmed the identity of three species: M. erythrini ex P. erythrinus and Pa. pagrus; M. isyebi Bouguerche, Gey, Justine & Tazerouti, 2019 ex B. boops; and a species new to science described herein, M. whittingtoni n. sp. ex D. dentex. The specific morphological traits and confirmed hosts (P. erythrinus and Pa. pagrus) are delimited here in order to avoid misidentifications of M. erythrini (sensu stricto). Microcotyle erythrini (s.s.) is mostly differentiated by the shape of its haptor, which is also longer than in the other congeners. New morphological and molecular data are provided for M. isyebi from the Spanish Mediterranean enlarging the data on its geographical range. Microcotyle whittingtoni n. sp. is described from D. dentex and distinguished from the remaining currently recognised species of the genus by the number and robustness of the clamps.
New diagnostic morphological traits useful to differentiate Microcotyle spp. are suggested: (i) haptor dimensions including lobes; (ii) the thickness of the clamps; (iii) the size and shape of spines of the genital atrium; (iv) the extension of the posterior extremities of vitelline fields; and (v) the shape of egg filaments. The use of new morphological approaches may allow considering these species of Microcotyle as being pseudocryptic. The use of representative undamaged specimens that have been genetically confirmed as conspecific is considered crucial to avoid abnormally wide morphological ranges that prevent species differentiation.
微盘虫属（Platyhelminthes：Monogenea）的微盘虫属和其他密切相关的物种通常被认为是隐密的。除了通过分子分析没有确认物种的模式宿主之外，在其他宿主中记录的情况促成了这种情况。
从西班牙西部地中海的五条鲷鱼，Boops boops（L.），Pagellus erythrinus（L.），P. acarne（Risso），Dentex dentex（L.）和Pagrus pagrus（L.）中收集了鳃寄生虫。微盘虫属的标本通过分子和形态学进行了描述。扩增了 28S rRNA 基因和细胞色素 c 氧化酶亚基 1（cox1）基因的部分片段（结构域 D1-D3），用于分子鉴定和系统发育重建。主成分分析用于寻找形态分离的模式。
分子分析证实了三种物种的身份：M. erythrini ex P. erythrinus 和 Pa. pagrus；M. isyebi Bouguerche，Gey，Justine 和 Tazerouti，2019 ex B. boops；以及本文描述的一种新科学物种，M. whittingtoni n. sp. ex D. dentex。为了避免微盘虫属（sensu stricto）的误认，这里限定了特定的形态特征和确认的宿主（P. erythrinus 和 Pa. pagrus）。M. erythrini（s.s.）主要通过其固着器的形状来区分，其形状也比其他同属的物种更长。本文提供了来自西班牙地中海的 M. isyebi 的新的形态学和分子数据，扩大了其地理范围的数据。M. whittingtoni n. sp. 从 D. dentex 中描述，与目前公认的该属的其他物种区分开来，其特征是夹钳的数量和粗壮。
提出了一些新的有用的形态学特征来区分微盘虫属：（i）固着器的尺寸包括叶；（ii）夹钳的厚度；（iii）生殖腔棘的大小和形状；（iv）卵黄场的后肢的延伸；和（v）卵丝的形状。使用新的形态学方法可以使这些微盘虫属的物种被认为是假隐密的。使用经过基因确认的有代表性的未受损标本是至关重要的，以避免阻止物种分化的异常宽的形态范围。
