Mendoza-Palmero Carlos A, Blasco-Costa Isabel, Hernández-Mena David, Pérez-Ponce de León Gerardo
Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, Apartado Postal 70-153, Código Postal 04510, México, D. F., Mexico.
Natural History Museum of Geneva, P.O. Box 6134, CH-1211 Geneva, Switzerland.
Parasitol Int. 2017 Apr;66(2):152-162. doi: 10.1016/j.parint.2017.01.006. Epub 2017 Jan 13.
Based on an integrative taxonomic approach, combining morphological characters and partial sequences of the 28S rRNA gene, a new genus and species, Parasciadicleithrum octofasciatum, is proposed to accommodate dactylogyrids infecting the gills of Rocio octofasciata (Cichlidae) from a tributary of the Lacantún River basin, Chiapas State, southern Mexico. Morphologically, the new genus resembles members of Sciadicleithrum (Dactylogyridae) in the presence of membranes on the anterior margins of both ventral and dorsal haptoral bars. However, Parasciadicleithrum octofasciatum n. sp. shows morphological differences with respect to a subset of species of Sciadicleithrum occurring in the same host group and geographic area, such as the body size and gonad dimensions (length and width of germarium and testis, respectively, smaller in the new genus). Phylogenetic analyses performed herein based on Maximum Likelihood and Bayesian Inference criteria, showed that Parasciadicleithrum octofasciatum n. sp. represents an undescribed taxon morphologically very similar to species of Sciadicleithrum from which it can be consistently distinguished on the basis of molecular data. P. octofasciatum n. sp. appeared genetically distant from Sciadicleithrum spp. and nested with dactylogyrid parasites of African cichlids. Parasciadicleithrum n. gen. showed divergence levels in the 28S rDNA sequences of 25-26% with respect to Sciadicleithrum spp. Therefore, on the basis of molecular evidence mainly, and morphological differences highlighted above, the erection of the new genus is proposed. The evolutionary and ecological factors that may have influenced the associations between Neotropical cichlids and their dactylogyrid parasites are briefly discussed.
基于综合分类学方法，结合形态特征和28S rRNA基因的部分序列，提出了一个新属和新种——八带副锯盘虫（Parasciadicleithrum octofasciatum），以容纳感染墨西哥南部恰帕斯州拉坎顿河流域一条支流中的罗氏丽体鱼（慈鲷科）鳃部的指环虫。在形态上，新属在腹侧和背侧柄杆前缘存在膜这一点上类似于锯盘虫属（指环虫科）的成员。然而，八带副锯盘虫新种与同一宿主群体和地理区域内的部分锯盘虫属物种在形态上存在差异，比如体型以及性腺尺寸（分别为卵巢和睾丸的长度和宽度，新属较小）。本文基于最大似然法和贝叶斯推断标准进行的系统发育分析表明，八带副锯盘虫新种代表了一个未描述的分类单元，其形态与锯盘虫属物种非常相似，但基于分子数据可以始终如一地将它们区分开来。八带副锯盘虫新种在基因上与锯盘虫属物种距离较远，并与非洲慈鲷的指环虫寄生虫聚在一起。副锯盘虫新属在28S rDNA序列上相对于锯盘虫属物种显示出25 - 26%的分歧水平。因此，主要基于分子证据以及上述突出的形态差异，提议建立新属。简要讨论了可能影响新热带区慈鲷与其指环虫寄生虫之间关联的进化和生态因素。
