Kmentová Nikol, Gelnar Milan, Koblmüller Stephan, Vanhove Maarten P M
Department of Botany and Zoology, Masaryk University , Brno , Czech Republic.
Institute of Zoology, University of Graz, Graz, Austria; Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Brno, Czech Republic.
PeerJ. 2016 Jan 25;4:e1629. doi: 10.7717/peerj.1629. eCollection 2016.
Monogenea is one of the most species-rich groups of parasitic flatworms worldwide, with many species described only recently, which is particularly true for African monogeneans. For example, Cichlidogyrus, a genus mostly occurring on African cichlids, comprises more than 100 nominal species. Twenty-two of these have been described from Lake Tanganyika, a famous biodiversity hotspot in which many vertebrate and invertebrate taxa, including monogeneans, underwent unique and spectacular radiations. Given their often high degrees of host specificity, parasitic monogeneans were also used as a potential tool to uncover host species relationships. This study presents the first investigation of the monogenean fauna occurring on the gills of endemic 'Gnathochromis' species along the Burundese coastline of Lake Tanganyika. We test whether their monogenean fauna reflects the different phylogenetic position and ecological niche of 'Gnathochromis' pfefferi and Gnathochromis permaxillaris. Worms collected from specimens of Limnochromis auritus, a cichlid belonging to the same cichlid tribe as G. permaxillaris, were used for comparison. Morphological as well as genetic characterisation was used for parasite identification. In total, all 73 Cichlidogyrus individuals collected from 'G.' pfefferi were identified as C. irenae. This is the only representative of Cichlidogyrus previously described from 'G.' pfefferi, its type host. Gnathochromis permaxillaris is infected by a species of Cichlidogyrus morphologically very similar to C. gillardinae. The monogenean species collected from L. auritus is considered as new for science, but sample size was insufficient for a formal description. Our results confirm previous suggestions that 'G.' pfefferi as a good disperser is infected by a single monogenean species across the entire Lake Tanganyika. Although G. permaxillaris and L. auritus are placed in the same tribe, Cichlidogyrus sp. occurring on G. permaxillaris is morphologically more similar to C. irenae from 'G.' pfefferi, than to the Cichlidogyrus species found on L. auritus. Various evolutionary processes, such as host-switching or duplication events, might underlie the pattern observed in this particular parasite-host system. Additional samples for the Cichlidogyrus species occuring on G. permaxillaris and L. auritus are needed to unravel their evolutionary history by means of (co-)phylogenetic analyses.
单殖吸虫是全球物种最为丰富的寄生扁虫类群之一，许多物种直到最近才被描述，非洲单殖吸虫尤其如此。例如，主要寄生于非洲丽鱼科鱼类的三代虫属包含100多个名义种。其中22种是在坦噶尼喀湖发现的，坦噶尼喀湖是著名的生物多样性热点地区，许多脊椎动物和无脊椎动物类群，包括单殖吸虫，都在该地区经历了独特而壮观的辐射演化。鉴于寄生单殖吸虫通常具有高度的宿主特异性，它们也被用作揭示宿主物种关系的潜在工具。本研究首次调查了坦噶尼喀湖布隆迪沿岸特有的“Gnathochromis”属鱼类鳃上的单殖吸虫动物区系。我们测试了它们的单殖吸虫动物区系是否反映了费氏Gnathochromis和巨颌Gnathochromis不同的系统发育位置和生态位。从与巨颌Gnathochromis属于同一丽鱼科部落的丽鱼科鱼类Limnochromis auritus的标本上采集的蠕虫用于比较。形态学和遗传学特征用于寄生虫鉴定。从费氏“Gnathochromis”采集的所有73个三代虫个体均被鉴定为伊氏三代虫。这是先前从其模式宿主费氏“Gnathochromis”描述的三代虫的唯一代表。巨颌Gnathochromis感染了一种形态上与吉氏三代虫非常相似的三代虫。从Limnochromis auritus采集的单殖吸虫物种被认为是科学上新发现的，但样本量不足以进行正式描述。我们的结果证实了先前的推测，即作为良好扩散者的费氏“Gnathochromis”在整个坦噶尼喀湖都被单一的单殖吸虫物种感染。尽管巨颌Gnathochromis和Limnochromis auritus属于同一部落，但寄生于巨颌Gnathochromis的三代虫在形态上与费氏“Gnathochromis”的伊氏三代虫比与Limnochromis auritus上发现的三代虫物种更相似。各种进化过程，如宿主转换或复制事件，可能是这个特定寄生虫 - 宿主系统中观察到的模式的基础。需要采集更多寄生于巨颌Gnathochromis和Limnochromis auritus的三代虫物种样本，通过（共）系统发育分析来揭示它们的进化历史。
