Although intertidal crabs from the western Atlantic coast are relatively well studied for some parasite fauna, their parasitic isopods are poorly known. We document two endoparasitic entoniscids (Cancrion carolinusPearse & Walker, 1939 and Cryptocancrion brevibrachiumn. gen., n. sp.) from mud (Brachyura: Panopeidae) and stone (Brachyura: Menippidae) crabs based on molecular and morphological data, including descriptions of their epicaridium larvae. Although these species cannot be distinguished based on adult female characters, molecular data and larval and male morphologies show that two species are present, sometimes sympatrically. The only other species of CancrionGiard & Bonnier, 1887 from the Atlantic coast of North America is Cancrion needleriPearse & Walker, 1939, described from adult specimens parasitizing Dyspanopeus sayi (Smith, 1869) from Prince Edward Island, Canada. Larvae of this species were never described and we consider it a species inquirenda. Cryptocancrion brevibrachiumn. gen., n. sp. is documented to have epicaridium larvae with a “short-armed” morphology (sixth pereopod subequal in length to pereopods 1–5), and the adults parasitize at least three mud crabs: D. sayi, Panopeus herbstiiH. Milne Edwards, 1834, and Rhithropanopeus harrisii (Gould, 1841). By contrast, Cancrion carolinus (originally described from P. herbstii collected in Beaufort, NC, USA) has epicaridium larvae with a “long-armed” morphology (sixth pereopod approximately twice the length of pereopods 1–5) and is found in at least four host species: Eurypanopeus depressus (Smith, 1869), P. herbstii, and R. harrisii and the stone crab Menippe mercenaria (Say, 1818). We describe C. brevibrachiumn. gen., n. sp. and redescribe C. carolinus based on type material and fresh specimens. The cryptic nature of these entoniscids indicates that examination of epicaridium larvae and/or molecular data are needed to properly identify species.

中文翻译：

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北美大西洋沿岸泥蟹 (Panopeidae) 内寄生等足类动物 (Bopyroidea: Entoniscidae) 的隐蔽多样性，以及分子和幼体特征揭示的新属和新种的描述：它的长和短

虽然西大西洋海岸的潮间带蟹对某些寄生动物群的研究相对较好，但它们的寄生等足类动物却鲜为人知。我们根据分子和形态学数据，记录了来自泥蟹（Brachyura：Panopeidae）和石蟹（Brachyura：Menippidae）的两种内寄生内寄生虫（Cancrion carolinusPearse＆Walker，1939 和 Cryptocancrion brevibrachiumn.gen.，n.sp.），包括它们的描述心外膜幼虫。虽然这些物种不能根据成年雌性特征来区分，但分子数据以及幼虫和雄性形态表明存在两个物种，有时是同域分布。Cancrion neederiPearse & Walker, 1939, 1887 年北美大西洋沿岸唯一的其他 Cancrion needleriPearse & Walker, 从寄生于加拿大爱德华王子岛的 Dyspanopeus sayi (Smith, 1869) 的成年标本中描述。该物种的幼虫从未被描述过，我们认为它是一个物种 quirenda。Cryptocancrion 短臂。将军，名词 sp。据记载，外膜幼虫具有“短臂”形态（第 6 个足足的长度与第 1-5 个足足亚等长），成虫寄生至少三种泥蟹：D. sayi、Panopeus herbstiiH。Milne Edwards，1834 年和 Rhithropanopeus harrisii（古尔德，1841 年）。相比之下，Cancrion carolinus（最初描述于美国北卡罗来纳州博福特的 P. herbstii）的外膜幼虫具有“长臂”形态（第六足足的长度大约是足足 1-5 的两倍），并且至少在四种宿主物种：Eurypanopeus depressus (Smith, 1869)、P. herbstii 和 R. harrisii 和石蟹 Menippe mercenaria（Say，1818 年）。我们描述了 C. brevibrachiumn。将军，名词 sp。并根据模式材料和新鲜标本重新描述C. carolinus。这些 entoniscids 的神秘性质表明需要检查外膜幼虫和/或分子数据才能正确识别物种。