Sardella Norma H, Mattiucci Simonetta, Timi Juan T, Bastida Ricardo O, Rodríguez Diego H, Nascetti Giuseppe
Laboratorio de Parasitología, Departamento de Biología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Funes 3350, 7600 Mar del Plata, Argentina.
Syst Parasitol. 2005 Jun;61(2):143-56. doi: 10.1007/s11230-005-3131-0.
Genetic and morphological studies were carried out on acanthocephalans belonging to Corynosoma Lühe, 1904 and referable to the species C. cetaceum Johnston & Best, 1942 and C. australe Johnston, 1937, which were recovered from both definitive and intermediate hosts in Argentinian waters. The aims were to estimate the level of genetic differentiation between the two taxa at any stage of their life-cycle, to provide genetic (allozyme) markers for their recognition and to analyse the systematic status of both taxa. Acanthocephalans were collected from the stomach and intestine of Arctocephalus australis (Zimmerman), the intestine of Mirounga leonina (Linnaeus) and the stomach of Pontoporia blainvillei Gervais & D'Orbigny (definitive hosts) in Argentinian waters. Alternative alleles at all the 13 enzymatic loci studied were observed for C. australe and C. cetaceum. The specimens from the stomach of both P. blainvillei and A. australis were identified, on the basis of the great number of diagnostic loci found, as C. cetaceum; those from intestine of both A. australis and M. leonina as C. australe. A high level of genetic differentiation (D(Nei)=infinity: I(Nei)=0.00) between the two taxa was found, suggesting a generic distinction between the two species. Cystacanths of the two species from the body-cavity of the fish Cynoscion guatucupa (Cuvier) collected from the same geographical area were identified genetically. Morphological patterns, such as the number of hooks and hook rows on the proboscis, the distribution of somatic and genital armature, and other morphometric and meristic differences, in addition to ecological data, enabled the identification of these two species at cystacanth, juvenile and adult stages. However, a number of morphological and morphometric features of the Argentinian material were different to those of C. australe and C. cetaceum described from other regions of the world.
对属于1904年吕厄的Corynosoma属、可归入1942年约翰斯顿和贝斯特的鲸Corynosoma cetaceum种以及1937年约翰斯顿的南方Corynosoma australe种的棘头虫进行了遗传学和形态学研究，这些棘头虫是在阿根廷海域的终末宿主和中间宿主中采集到的。目的是估计这两个分类单元在其生命周期的任何阶段的遗传分化水平，为其识别提供遗传（等位酶）标记，并分析这两个分类单元的系统地位。棘头虫是从阿根廷海域的南极毛皮海狮（齐默尔曼）的胃和肠道、南象海豹（林奈）的肠道以及白氏海豚（热尔韦和多尔比尼）的胃（终末宿主）中采集到的。在研究的所有13个酶位点上，均观察到了南方Corynosoma australe种和鲸Corynosoma cetaceum种的替代等位基因。根据发现的大量诊断位点，来自白氏海豚和南极毛皮海狮胃中的标本被鉴定为鲸Corynosoma cetaceum种；来自南极毛皮海狮和南象海豹肠道中的标本被鉴定为南方Corynosoma australe种。发现这两个分类单元之间存在高度的遗传分化（内氏遗传距离D =无穷大：内氏遗传相似度I = 0.00），这表明这两个物种在属级上存在区别。对从同一地理区域采集的瓜氏犬牙石首鱼（居维叶）体腔中的这两个物种的囊尾蚴进行了遗传学鉴定。除了生态数据外，形态学特征，如吻上的钩数和钩排数、体表和生殖器官的分布以及其他形态测量和分节差异，使得能够在囊尾蚴、幼体和成体阶段识别这两个物种。然而，阿根廷材料的一些形态学和形态测量特征与世界其他地区描述的南方Corynosoma australe种和鲸Corynosoma cetaceum种不同。
