de Chambrier Alain, Pinacho-Pinacho Carlos Daniel, Hernández-Orts Jesus Servando, Scholz Tomáš
Department of Invertebrates, Natural History Museum, P.O. Box 6434, 1211 Geneva, Switzerland.
J Parasitol. 2017 Feb;103(1):83-94. doi: 10.1645/16-84. Epub 2016 Oct 20.
Cichlidocestus n. gen. is proposed to accommodate 2 new species of proteocephalidean cestodes, Cichlidocestus gillesi n. sp. from Cichlasoma amazonarum in Peru (type species) and Cichlidocestus janikae n. sp. from Hypsophrys nicaraguensis (all Perciformes: Cichlidae) in Costa Rica. The new genus is unique among all but 1 proteocephalidean genera in the position of the ovary that occupies the middle and posterior thirds of the median region of proglottids (vs. the ovary in the posterior third of proglottids near their posterior margin in all but 1 remaining taxa). In addition, Cichlidocestus is typified by the presence of a voluminous, spherical, internal seminal vesicle, several pairs of ventral excretory canals in the medulla, a pyramidal, quadrilobed scolex with an apical muscular sucker, and the posterior extent of the testes that may reach almost to the posterior margin of proglottids. The new genus shares the position of the ovary and its extension with Sciadocephalus (also a parasite of cichlids in the Neotropics as the new taxon); in all remaining proteocephalideans the ovary occupies the posterior third only. Sciadocephalus differs from Cichlidocestus by a different morphology of the scolex, which possesses an umbrella-like metascolex that is markedly wider than the strobila, the number of ventral osmoregulatory canals, and development of the uterus, which forms capsule-like formations filled with eggs in Sciadocephalus megalodiscus (vs. simple lateral diverticula in Cichlidocestus spp.). Both new species of Cichlidocestus can be easily distinguished from one another by the anterior extent of the poral vitelline follicles (anterior to the cirrus-sac, i.e., preporal, in C. gillesi vs. posterior, i.e., only postporal in C. janikae), size of the eggs (diameter of the external layer of the embryophore of C. gillesi 30-33 μm vs. 44-46 μm in C. janikae), and the number of uterine lateral diverticula (16-21 on 1 side in C. gillesi vs. only 8-12 in C. janikae) and the testes (37-46 in C. gillesi vs. 63-74 in C. janikae). Based on a phylogenetic analysis of the 28S rRNA gene (lsrDNA) sequences, C. gillesi forms a lineage sister to S. megalodiscus, thus supporting the morphological similarity of both genera that occur in fishes of the same family in the same zoogeographical region.
新属丽体绦虫属（Cichlidocestus n. gen.）被提议用于容纳两种新的原头节绦虫，即来自秘鲁亚马逊丽体鱼（Cichlasoma amazonarum）的吉氏丽体绦虫（Cichlidocestus gillesi n. sp.，模式种）和来自哥斯达黎加尼加拉瓜高身丽鱼（Hypsophrys nicaraguensis，均为鲈形目：丽鱼科）的雅妮卡丽体绦虫（Cichlidocestus janikae n. sp.）。在所有原头节绦虫属中，除了一个属外，新属的卵巢位置独特，占据节片中部和后三分之一的中区域（相比之下，除了一个剩余类群外，其他所有类群的卵巢位于节片后三分之一靠近其后缘处）。此外，丽体绦虫属的特征还包括有一个体积大的球形内贮精囊、髓质中有几对腹排泄管、一个带有顶端肌肉吸盘的金字塔形、四边形头节，以及睾丸向后延伸可能几乎到达节片后缘。新属在卵巢位置及其延伸方面与头扇绦虫属（Sciadocephalus，也是新热带区丽鱼的寄生虫，如同新分类单元）相同；在所有其他原头节绦虫中，卵巢仅占据后三分之一。头扇绦虫属与丽体绦虫属的区别在于头节形态不同，头扇绦虫属具有一个伞状后体节，明显比节片宽，腹渗透压调节管的数量，以及子宫的发育情况，在大圆盘头扇绦虫（Sciadocephalus megalodiscus）中子宫形成充满卵的囊状结构（相比之下，丽体绦虫属物种为简单的侧支囊）。丽体绦虫属的两个新物种可以通过卵黄滤泡的前部范围（吉氏丽体绦虫的卵黄滤泡在阴茎囊前方，即阴茎前，而雅妮卡丽体绦虫的在后方，即仅阴茎后）、卵的大小（吉氏丽体绦虫胚胎膜外层直径为30 - 33μm，而雅妮卡丽体绦虫为44 - 46μm）、子宫侧支囊的数量（吉氏丽体绦虫一侧有16 - 21个，而雅妮卡丽体绦虫仅8 - 12个）以及睾丸数量（吉氏丽体绦虫有37 - 46个，而雅妮卡丽体绦虫有63 - 74个）轻易区分开来。基于对28S rRNA基因（lsrDNA）序列的系统发育分析，吉氏丽体绦虫形成了一个与大圆盘头扇绦虫姐妹的谱系，从而支持了在同一动物地理区域同一科鱼类中出现的这两个属的形态相似性。
