Institute of Parasitic Diseases, 11445 E. Via Linda 2-419, Scottsdale, AZ85259, USA.
Department of Biology, Brigham Young University, 1114 MLBM, Provo, UT84602, USA.
J Helminthol. 2021 Jan 28;95:e3. doi: 10.1017/S0022149X20001005.
Pallisentis (Pallisentis) nandai Sarkar, 1953 is a freshwater fish parasite restricted to the Indian subcontinent in the Ganga River and its tributaries. It was described from the leaffish, Nandus nandus (Hamilton) from the Ganga River delta at Calcutta. We recovered variant specimens from the same host species from the Ganga near its headwaters at Bijnor about 1500 km away. Our specimens were clearly identifiable as P. nandai but varied considerably from those in the original description, especially in the size of proboscis hooks, receptacle and lemnisci. The original description was incomplete (missing line drawings of female trunk and reproductive system, male trunk, complete proboscis, hooks and hook roots) and inaccurate (proboscis, hooks, receptacle wall), and some measurements were lumped together for both sexes. We provide a complete description and include new morphological information including the first description of para-receptacle structure in the genus Pallisentis Van Cleave, 1928, scanning electron microscopy and microscope images, molecular analysis, and energy dispersive X-ray analysis (EDXA) of hooks and spines of our specimens for the first time. Additional details of proboscis hook roots, trunk spines, micropores and micropore distribution are described. The unique metal composition of hooks (EDXA) demonstrated a considerably high but variable level of sulphur and negligible level of calcium in collar and trunk spines and hook tips, but a higher level of sulphur and calcium at the hook basal arch than at the hook tip and edge. A comparison with the EDXA pattern of another species of Pallisentis, P. İndica Mital & Lal, 1976, were considerably different. The phylogenetic position of P. nandai within Eoacanthocephala was generated to assess the molecular characterization based on 18S and ITS1-5.8S-ITS2 ribosomal DNA sequences. Maximum likelihood and Bayesian inference analyses placed P. nandai in a clade with other Pallisentis species under the family Quadrigyridae. This is the first report based on molecular evidence for P. nandai.
纳氏囊棘虫（Pallisentis）是一种淡水鱼类寄生虫，仅分布于印度次大陆的恒河及其支流。它是由加尔各答恒河三角洲的叶鱼，Nandus nandus（Hamilton）描述的。我们从距离加尔各答约 1500 公里的贝拿勒斯（Bijnor）上游的恒河中采集到同一宿主物种的变异标本。我们的标本显然可以识别为纳氏囊棘虫，但与原始描述中的标本有很大的不同，尤其是吻钩、接收囊和 Lemnisci 的大小。原始描述不完整（缺少雌性躯干和生殖系统、雄性躯干、完整的吻、钩和钩根的线条图）且不准确（吻、钩、接收囊壁），一些测量值也男女混合在一起。我们提供了一个完整的描述，并包括新的形态学信息，包括在 Pallisentis Van Cleave，1928 属中首次描述的副接收囊结构，扫描电子显微镜和显微镜图像，分子分析，以及我们标本的钩和刺的能量色散 X 射线分析（EDXA）。描述了吻钩根、躯干刺、微孔和微孔分布的更多细节。钩（EDXA）的独特金属组成显示出相当高但可变的硫水平和 collar 和躯干刺以及钩尖端的钙水平可以忽略不计，但钩基弓的硫和钙水平高于钩尖端和边缘。与另一种囊棘虫 Pallisentis 的 EDXA 模式进行比较，发现它们的模式差异很大。在 Eoacanthocephala 中，对 P. nandai 的系统发育位置进行了生成，以评估基于 18S 和 ITS1-5.8S-ITS2 核糖体 DNA 序列的分子特征。最大似然和贝叶斯推断分析将 P. nandai 置于 Quadrigyridae 科中的其他 Pallisentis 物种的一个分支中。这是基于分子证据首次报道的 P. nandai。
