Domingues M V, Marques F P L
Laboratório de Helmintologia Evolutiva, Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, n° 101 Cidade Universitária, 05508-090, São Paulo, SP, Brazil.
J Helminthol. 2011 Dec;85(4):353-80. doi: 10.1017/S0022149X10000684. Epub 2010 Nov 19.
The marine-derived stingrays of Potamotrygonidae, endemic to South American river systems, host an interesting parasite fauna equally related to marine lineages. Among those lineages, the diversity and phylogenetic relationships within Potamotrygonocotyle - a monocotylid monogenoidean specific to potamotrygonids - are poorly known, since 9 of 10 species attributed to this genus have been described in the past 3 years. Here, we readdress the diversity of Potamotrygonocotyle after examining the gills of 436 potamotrygonid individuals representing 12 described and 14 potentially undescribed species of freshwater stingrays from 19 major river systems of South America (i.e. sub-basins). We recognized 12 valid species within the parasite genus, of which four are described in this study. Our taxonomic decisions were based on the phylogenetic analysis of 14 ingroup terminal taxa and 12 morphological characters, which resulted in the following hypothesis of sister-group relationships: ((P. dromedarius, P. tatianae sp. nov.), (P. rionegrense, P. auriculocotyle sp. nov., ((P. quadracotyle, P. umbella), (P. septemcotyle sp. nov., (P. chisholmae, P. uruguayense)), (P. tsalickisi, P. eurypotamoxenus, P. rarum, (P. tocantinsense sp. nov., P. aramasae))))). According to our hypothesis, the absence of autapomorphic features for some nominal species, and the re-evaluation of morphological variation among populations, led us to consider P. eurypotamoxenus and P. uruguayense as junior synonymys of P. tsalicksi and P. chisholmae, respectively. Finally, we address the importance of biogeographic and host representation, in order to fully understand the patterns of morphological variation and host specificity within this group. We found that hypotheses of species delimitation depend greatly on efforts to sample specimens throughout its distributional range and that host specificity within this genus varies dramatically among lineages.
原产于南美河流系统的淡水魟科淡水魟，寄带着有趣的寄生虫群落，这些寄生虫同样与海洋谱系有关。在这些谱系中，淡水魟单殖吸虫（Potamotrygonocotyle）——一种特化于淡水魟的单殖吸虫——的多样性和系统发育关系鲜为人知，因为在过去3年里，归于该属的10个物种中有9个被描述。在此，我们在检查了436个淡水魟个体的鳃后，重新审视了淡水魟单殖吸虫的多样性，这些个体代表了来自南美19个主要河流系统（即次流域）的12个已描述和14个可能未描述的淡水魟物种。我们在该寄生虫属中识别出12个有效物种，其中4个在本研究中被描述。我们的分类学决策基于对14个内群终端分类单元和12个形态特征的系统发育分析，得出了以下姐妹群关系假说：（（单峰淡水魟（Potamotrygon dromedarius），塔蒂亚娜淡水魟新种（P. tatianae sp. nov.）），（里奥内格罗淡水魟（P. rionegrense），耳状盘淡水魟新种（P. auriculocotyle sp. nov.），（（四盘淡水魟（P. quadracotyle），伞形淡水魟（P. umbella）），（七盘淡水魟新种（P. septemcotyle sp. nov.），（奇肖尔姆淡水魟（P. chisholmae），乌拉圭淡水魟（P. uruguayense）））），（察利克斯基淡水魟（P. tsalickisi），宽河淡水魟（P. eurypotamoxenus），稀有淡水魟（P. rarum），（托坎廷斯淡水魟新种（P. tocantinsense sp. nov.），阿拉马萨淡水魟（P. aramasae））））。根据我们的假说，一些命名物种缺乏自近裔性状，以及对种群间形态变异的重新评估，使我们分别将宽河淡水魟和乌拉圭淡水魟视为察利克斯基淡水魟和奇肖尔姆淡水魟的次异名。最后，我们阐述了生物地理学和宿主代表性的重要性，以便充分理解该类群内形态变异和宿主特异性的模式。我们发现，物种界定假说在很大程度上取决于在整个分布范围内对标本进行采样的努力，并且该属内的宿主特异性在不同谱系间差异很大。
