Department of Biology, Center for Liberal Arts & Sciences, Iwate Medical University, Yahaba-cho, Shiwa-gun, Iwate, Japan.
Faculty of Science and Engineering, Ishinomaki Senshu University, Ishinomaki, Miyagi, Japan.
PeerJ. 2022 Aug 25;10:e13909. doi: 10.7717/peerj.13909. eCollection 2022.
There are currently two species within the small enigmatic genus Mackie & Duff, 1986, which belongs to the - group in the family Spionidae Grube, 1850. The taxonomic relationship of the genus with other spionid or spioniform genera is currently not well understood due to its unusual morphological characteristics.
Here, we describe a new species, , based on materials collected from three localities in Japan: Hirota Bay (Iwate Prefecture), Ago Bay (Mie Prefecture), and Yakushima Island (Kagoshima Prefecture). We have also evaluated the possible systematic position of this new species by conducting molecular phylogenetic analyses using the nuclear 18S, 28S, and mitochondrial 16S rRNA gene sequences.
The morphology of . resembles that of Mackie & Duff, 1986 and . (Laubier & Ramos, 1974) in having branchiae fused to the notopodial lamellae on a restricted number of segments from chaetiger 7, modified neurochaetae on chaetiger 5, and at least some bidentate neuropodial hooks with the secondary tooth below the main fang. The form and arrangement of the modified aristate neurochaetae in double vertical rows closely resemble those found on chaetigers 4 and 5 of . The new species lacks the occipital antenna present in . . In this respect it resembles . , however, that species differs in having robust neuropodial spines on chaetiger 5 and peristomial papillae, and a preponderance of unidentate neurochaetae. Both and the new species have slender needle-like notochaetae in their posteriormost chaetigers. is distinguished from both congeneric species by its branchial and neuropodial hook distributions. The new species is also unique in that it was recorded at relatively shallow depths, which included intertidal zones. The results of our molecular phylogenetic analysis indicate that the new species was included in a clade that included the genera of the complex, Claparède, 1863, Meißner, Bick, Guggolz, Götting, 2014, Fabricius, 1785, Mesnil, 1896, Mesnil, 1896, Hartman, 1936, Blainville, 1828, Hartman, 1951, and Quatrefages, 1843 with robust statistical support. The new species formed a clade with and , however, statistical support for the node was not significant.
目前，Mackie & Duff，1986 属内有两个种，属于 Spionidae Grube，1850 家族中的 - 组。由于其不寻常的形态特征，该属与其他 spionid 或 spioniform 属之间的分类关系目前还不太清楚。
本文基于在日本三个地点采集的材料，描述了一个新的 Mackie & Duff，1986 属物种，即 。我们还通过使用核 18S、28S 和线粒体 16S rRNA 基因序列进行分子系统发育分析，评估了这个新物种的可能系统位置。
. 的形态与 Mackie & Duff，1986 和 Laubier & Ramos，1974 的形态相似，具有从第 7 体节开始的有限数量的体节上的鳃融合到前刚毛鳞片上、第 5 体节上的改性神经刚毛、以及至少一些具二次齿的双叉神经足钩，其二级齿在主齿下方。改性的有刺神经刚毛的形状和排列与第 4 和第 5 体节上发现的非常相似。新种没有 Mackie & Duff，1986 中存在的枕触角。在这方面，它类似于 ，但该物种在第 5 体节上具有粗壮的神经足刺和口围乳突，并且具有优势的单齿神经刚毛。 和新种在它们的后体节中都具有细长的针状刚毛。 与同属的两个种不同，其鳃和神经足钩的分布不同。新种还具有独特的特点，即它在相对较浅的深度记录到，包括潮间带。我们的分子系统发育分析结果表明，新种包含在一个包含 复杂属、Claparède，1863、Meißner、Bick、Guggolz、Götting，2014、Fabricius，1785、Mesnil，1896、Mesnil，1896、Hartman，1936、Blainville，1828、Hartman，1951 和 Quatrefages，1843 的属的进化枝中，具有稳健的统计支持。新种与 和 形成一个进化枝，然而，节点的统计支持并不显著。
