The acanthocephalan Macracanthorhynchus ingens (von Linstow 1879) (Acanthocephala: Archiacanthocephala) is a parasite that infects the gut of carnivores (racoons, coyotes, wolves, foxes, badgers, skunks, opossum, mink and bears) as an adult and the body cavity of lizards, snakes, and frogs as a cystacanth in the Americas. In this study, adults and cystacanths of M. ingens from southeastern Mexico and southern Florida, USA, were identified morphologically by having a cylindrical proboscis armed with 6 rows of hooks each with 6 hooks. Hologenophores were used to sequence the small (SSU) and large (LSU) subunits of ribosomal DNA and cytochrome c oxidase subunit 1 (cox 1) from mitochondrial DNA. Phylogenetic analysis of the new SSU and LSU sequences of M. ingens placed them in a clade with other sequences available in GenBank identified as M. ingens. The cox 1 tree showed that the nine new sequences and six previously published sequences of M. ingens from the USA form a clade with other sequences previously identified as M. ingens from GenBank. The intraspecific genetic divergence among isolates from the Americas ranged from 0 to 2%, and in combination with the phylogenetic trees confirmed that the isolates belonged to the same species. The cox 1 haplotype network inferred with 15 sequences revealed 10 haplotypes separated from each other by a few substitutions. Rio Grande Leopard Frogs and Vaillant´s Frogs harbored cystacanths with low prevalence, 28% and 37% respectively, in Mexico. Brown Basilisks, an invasive lizard in Florida, USA, had high values of prevalence, 92% and 93% in males and females, respectively. Females harbored more cystacanths than males (0–39 vs 0–21) for unknown reasons that may, however, be related to ecological differences.

棘头动物Macracanthorhynchus ingens (von Linstow 1879) (棘头动物: Archiacanthocephala) 是一种寄生虫，成年后会感染食肉动物（浣熊、郊狼、狼、狐狸、獾、臭鼬、负鼠、水貂和熊）的肠道，以及感染食肉动物的体腔。在美洲，蜥蜴、蛇和青蛙都属于囊棘鱼。在这项研究中，来自墨西哥东南部和美国佛罗里达州南部的M. ingens的成虫和囊棘虫通过形态学上的鉴定，其具有配备有 6 排钩子的圆柱形长鼻，每排钩子有 6 个钩子。使用全息团对核糖体 DNA 的小 (SSU) 和大 (LSU) 亚基以及线粒体 DNA 中的细胞色素 c 氧化酶亚基 1 ( cox 1 ) 进行测序。对M. ingens的新 SSU 和 LSU 序列进行系统发育分析，将它们与 GenBank 中识别为M. ingens 的其他序列放在一个进化枝中。cox 1树显示来自美国的9 个新序列和 6 个先前发表的M. ingens序列与先前从 GenBank鉴定为M. ingens 的其他序列形成一个分支。美洲分离株间的种内遗传差异为0%~2%，结合系统发育树证实这些分离株属于同一物种。用 15 个序列推断的cox 1单倍型网络揭示了 10 个单倍型，这些单倍型通过一些替换彼此分开。在墨西哥，里奥格兰德豹蛙和威能蛙的囊刺蛙患病率较低，分别为 28% 和 37%。布朗蜥蜴是美国佛罗里达州的一种入侵蜥蜴，其患病率很高，雄性和雌性分别为 92% 和 93%。雌性比雄性拥有更多的囊刺（0-39 vs 0-21），原因未知，但可能与生态差异有关。