Milnesium (Tardigrada: Apochela) having elongated buccal tube from Mt. Yukikuradake (Toyama and Niigata prefecture, Japan)

IF 1.5 3区生物学 Q2 ZOOLOGY

Zoologischer Anzeiger Pub Date : 2025-07-01 DOI:10.1016/j.jcz.2025.06.004

Kenta Sugiura , Atsushi C. Suzuki

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引用次数: 0

Abstract

The order Apochela (Tardigrada: Eutardigrada) includes Milnesium and three monospecific genera Limmenius, Milnesioides, and Bergtrollus. These three genera have elongated buccal tubes and are found from limited areas in the world: Australia, New Zealand, and the Lyngen Alps in Norway, respectively. The existence of such milnesiids having elongated buccal tube in Japan was once reported at a conference but it has not been described further.

We found the undescribed species again in summer 2023. From a moss sample on the summit of Mt. Yukikuradake, we obtained milnesiid specimens having a narrow, elongated buccal tube. Although the morphological data corresponded to the genus Bergtrollus, molecular phylogeny clearly indicated that the species belonged to the genus Milnesium; therefore, we describe it as Milnesium utsugii sp. nov. Molecular phylogenetic analysis also showed that Milnesioides spp. and M. utsugii sp. nov. were clearly delimited, suggesting that the elongated-mouth evolved at least two times in the family Milnesiidae. Hatchlings of the new species had higher buccal tube width/length ratio compared to the adults, indicating a developmental change to a longer and narrower shape.

This is the fourth species of the genus Milnesium in Japan. Interestingly, the moss sample at the type locality of the new species housed another undescribed Milnesium which was placed within a clade with an undescribed Norwegian species, implying a relationship in zoogeographic histories between M. utsugii sp. nov., Bergtrollus, and the undescribed Milnesium.

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产自日本富山和新泻县的有细长颊管的千禧年虫（缓步目：背肢目）

步足目（缓步目：准缓步目）包括千禧年目和三个单一属Limmenius、Milnesioides和Bergtrollus。这三个属有细长的颊管，分别在世界上有限的地区发现：澳大利亚，新西兰和挪威的林根阿尔卑斯山。日本曾在一次会议上报道过这种口腔管延长的千禧年虫的存在，但没有进一步的描述。我们在2023年夏天再次发现了未被描述的物种。从Yukikuradake山山顶的苔藓样本中，我们获得了具有窄而细长的颊管的千齿类标本。虽然形态资料属于Bergtrollus属，但分子系统发育明确表明该种属于Milnesium属；分子系统发育分析也表明Milnesioides sp.和m.u utsugii sp. nov.有明显的分界，表明milnesiides spp.和m.u utsugii sp. nov.在Milnesiidae中至少进化了两次。与成虫相比，新种幼体的颊管宽长比更高，表明其发育形态向较长较窄的方向发展。这是日本千禧年属的第四种。有趣的是，在新物种的模式地点的苔藓样本中，另一个未被描述的千禧年物种被放置在一个未被描述的挪威物种的分支中，这意味着M. utsugii sp. nov， Bergtrollus与未被描述的千禧年物种之间在动物地理历史上的关系。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Zoologischer Anzeiger 生物-动物学

CiteScore

2.80

自引率

7.10%

发文量

审稿时长

>12 weeks

期刊介绍： Zoologischer Anzeiger - A Journal of Comparative Zoology is devoted to comparative zoology with a special emphasis on morphology, systematics, biogeography, and evolutionary biology targeting all metazoans, both modern and extinct. We also consider taxonomic submissions addressing a broader systematic and/or evolutionary context. The overall aim of the journal is to contribute to our understanding of the organismic world from an evolutionary perspective. The journal Zoologischer Anzeiger invites suggestions for special issues. Interested parties may contact one of the editors.