Braicovich Paola E, Lanfranchi Ana L, Farber Marisa D, Marvaldi Adriana E, Luque José L, Timi Juan T
Folia Parasitol (Praha). 2014 Aug;61(4):377-84.
Gymnorhadinorhynchus gen. n. is proposed to accommodate its type species, G. decapteri sp. n., a parasite of the marine fish Decapterus punctatus (Cuvier), caught from the coastal waters of Brazil. Gymnorhadinorhynchus decapteri sp. n. was morphologically most similar to species of two echinorhynchid families, the Rhadinorhynchidae and the Cavisomidae, particularly in the structure of the proboscis and the absence of somatic spines, respectively. This combination of morphological features made it difficult to assign our specimen to an extant family of the Acanthocephala. Therefore, in order to clarify the systematic placement of G. decapteri, a molecular phylogenetic analysis was performed based on the SSU and LSU rDNA and the mitochondrial cox1 gene sequences obtained for the new taxon and other 26 acanthocephalan species. The results of parsimony and maximum likelihood analyses, using individual, combined and concatenated sequence data, consistently indicate that the specimens do not belong to any known family of the Echinorhynchida. Rather, G. decapteri represents a distinct lineage that is closely related to the Transvenidae, but distantly related to both the Rhadinorhynchidae and the Cavisomidae. Gymnorhadinorhynchidae fam. n. is therefore erected. This newly described family can be distinguished from other families of Echinorhynchida by the combination of the following morphological characters: a proboscis cylindrical with 10 rows of 22-26 hooks, dorsoventral differences in proboscis hooks, basal hooks forming a ring and being abruptly larger than anterior hooks, absence of trunk spines and presence of four tubular cement glands. This combination, in addition to several molecular autapomorphies, justifies the erection of a new genus, Gymnorhadinorhynchus gen. n., in order to accommodate this new species.
新属裸吻棘头虫属（Gymnorhadinorhynchus gen. n.）被提出以容纳其模式种——裸吻棘头虫（G. decapteri sp. n.），该寄生虫寄生于从巴西沿海水域捕获的斑鰶（Decapterus punctatus，居维叶）体内。裸吻棘头虫在形态上与棘吻科（Rhadinorhynchidae）和腔吻科（Cavisomidae）这两个棘吻虫科的物种最为相似，分别尤其体现在吻的结构和体表无棘方面。这种形态特征的组合使得将我们的标本归入棘头虫纲现有的科变得困难。因此，为了阐明裸吻棘头虫的系统位置，基于从小亚基（SSU）和大亚基（LSU）核糖体DNA以及为新分类单元和其他26种棘头虫物种获得的线粒体细胞色素氧化酶亚基1（cox1）基因序列进行了分子系统发育分析。使用单独、组合和串联序列数据进行的简约分析和最大似然分析结果一致表明，这些标本不属于棘吻目任何已知的科。相反，裸吻棘头虫代表一个独特的谱系，与横吻科密切相关，但与棘吻科和腔吻科都关系较远。因此，建立了裸吻棘头虫科（Gymnorhadinorhynchidae fam. n.）。这个新描述的科可以通过以下形态特征的组合与棘吻目的其他科区分开来：吻呈圆柱形，有10排22 - 26个钩，吻钩存在背腹差异，基部钩形成一个环且比前部钩突然大得多，无躯干棘且有四个管状粘腺。除了几个分子自近裔性状外，这种组合证明建立一个新属——裸吻棘头虫属（Gymnorhadinorhynchus gen. n.）以容纳这个新物种是合理的。
