We report the extraordinarily preserved euarthropod Sidneyia minor sp.nov.from the Cambrian Stage 3 Xiaoshiba Lagerst?tte in Yunnan,South China.So far this is the earliest occurrence of the genus.As with other species of Sidneyia,the new taxon shares similar features such as a crescent-shaped head shield with paired lateral notches for stalked eyes,but more significantly and new,is the presence of three pairs of post-antennal appendages beneath the head shield identified by micro-CT methods.We conclude that Sidneyia is a sister group to other members of Vicissicaudata within the diverse radiation of Artiopoda.
文章报道了产自云南寒武系第三阶小石坝生物群的小西德尼虫新种(Sidneyia minor sp.nov.),为西德尼虫属(Sidneyia)目前所发现的最古老物种.该新种具有其他已知小西德尼虫的一些典型特征,如新月形的头甲两侧后部具眼窝(notches),柄眼从眼窝处伸出,此外,最重要而且从未知晓的是显微-CT检测显示的头甲下3对触角后头部附肢.文章基于小西德尼虫新种和模式种的特征以及谱系分析结果,确认西德尼虫类与其他的异尾虫类(vicissicaudatans)构成姊妹群,归属物种显著分异的类肢动物(Artiopoda).
Spiders are among the most varied terrestrial predators,with highly diverse morphology,ecology,and behavior.Morphological and molecular data have greatly contributed to advances in the phylogeny and evolutionary dynamics of spiders.Here,we performed comprehensive mitochondrial phylogenomics analysis on 78 mitochondrial genomes(mitogenomes)representing 29 families;of these,23 species from eight families were newly generated.Mesothelae retained the same gene arrangement as the arthropod ancestor(Limulus polyphemus),while Opisthothelae showed extensive rearrangement,with 12 rearrangement types in transfer RNAs(tRNAs)and control region.Most spider tRNAs were extremely truncated and lacked typical dihydrouridine or TΨC arms,showing high tRNA structural diversity;in particular,trnS1 exhibited anticodon diversity across the phylogeny.The evolutionary rates of mitochondrial genes were potentially associated with gene rearrangement or truncated tRNAs.Both mitogenomic sequences and rearrangements possessed phylogenetic characteristics,providing a robust backbone for spider phylogeny,as previously reported.The monophyly of suborder,infraorder,retrolateral tibial apophysis clade,and families(except for Pisauridae)was separately supported,and high-level relationships were resolved as(Mesothelae,(Mygalomorphae,(Entelegynae,(Synspermiata,Hypochilidae)))).The phylogenetic positions of several families were also resolved(e.g.,Eresidae,Oecobiidae and Titanoecidae).Two reconstructions of ancestral web type obtained almost identical results,indicating that the common ancestor of spiders likely foraged using a silk-lined burrow.This study,the largest mitochondrial phylogenomics analysis of spiders to date,highlights the usefulness of mitogenomic data not only for providing efficient phylogenetic signals for spider phylogeny,but also for characterizing trait diversification in spider evolution.
Min LiWen-Ting ChenQi-Lin ZhangMin LiuCheng-Wei XingYa CaoFang-Zhen LuoMing-Long Yuan
Eurypterids,or sea scorpions,are an important group of midPaleozoic chelicerate arthropods whose evolution and palaeoecological significance have attracted much attention in recent years[1–3].One of the most remarkable eurypterid families is Mixopteridae,whose members are quite large and superficially scorpion-like eurypterids bearing highly specialized anterior appendages.Their second,and especially the third,pair of prosomal limbs are enlarged and very spiny.These limbs were presumably used for prey-capture,and analogies can be drawn with the “catching basket”[4]formed by the spiny pedipalps of whip spiders(Amblypygi)among the arachnids.
Han WangJason DunlopZhikun GaiXiaojie LeiEdmund A.JarzembowskiBo Wang
Two new species of Protura are described:Baculentulus wenyingae sp.nov.and Pseudanisentomon lishuiensis sp.nov.Baculentulus wenyingae sp.nov.is characterized by the combined characters of the presence of foretarsal sensillum b',differentiated sensilla on the maxillary palp,leaf-shaped sensillum on the labial palp,absence of P1a seta on tergites I–VI,eight anterior setae on tergite VI and 4/18 chaetotaxy on tergite VII.An updated key to the 13 Baculentulus species from China is also provided.Pseudanisentomon lishuiensis sp.nov.is characterized by the absence of foretarsal sensillum b'-2,b longer than c,the empodial appendage of II and III leg very short,the tergite I with 12 posterior setae,tergites V–VII lack seta A3,and sternites VIII–X with 2/7-4-4 chaetotaxy respectively.It was compared with the affiliated species P.guangxiensis(Yin&Zhang,1982)in detail.In addition,a checklist and the distribution of 39 Protura species from Zhejiang Province are provided,and the Protura fauna in Zhejiang is also discussed.
本文描述了贵州剑河八郎寒武系第二统第四阶"清虚洞组"剑河生物群的高肌虫化石。化石壳体呈圆形,背边平直,前、后背角均钝,壳前背部具有"V"形槽。符合Qingquanella Cui et Huo,1985的属征,与模式种湖北清泉虫Q.hubeiensis相似,将其厘定为湖北清泉虫相似种Q.cf.hubeiensis。本属产于湖北水井沱组、石牌组及陕西辛集组,黔东地区"清虚洞组"发现清泉虫Qingquanella,增加了清泉虫的产地信息、新的类群,其壳体形态由切卵变圆形,生态环境由浅水向深水变化,为高肌虫的形态分类、早期演化与辐射分异提供新的材料。