细丝海绵科是一类骨骼薄, 由横向与纵向单轴针构成内外两层骨骼结构的海绵类群, 传统上被归到普通海绵纲。而最近在类似细丝海绵的化石研究中发现了六射海绵纲的特征, 即保存有六射骨针或其衍生类型骨针, 并对细丝海绵类曾被归到普通海绵纲的系统发育位置提出疑问。若要厘清其系统发育位置, 需要对前人描述过的细丝海绵类群进行更详细的研究或发现新的化石材料。最近在贵州遵义地区牛蹄塘组中发现的新材料 Paraleptomitella zunyiensis sp. nov.和P. reticula sp. nov.不仅具有细丝海绵类(leptomitids)以单轴针为主的双层骨架, 还保存有三轴针(或其衍生骨针)。新材料这一独特骨针组合, 表明其可能与六射海绵亲缘关系更近, 为厘清细丝海绵的系统发育位置和早期海绵动物的起源与演化提供新信息。

The Leptomitidae is a family of sponges characterized by a thin skeletal framework composed of a two-layered architecture with longitudinally and transversely arranged monaxons. Traditionally, they are classified within the Demospongiae. Recently, some researchers have identified hexactine-based spicules, skeletal elements restricted to the class Hexactinellida, in some leptomitid-like fossils. Therefore, the phylogenetic position of the leptomitids requires new data for reassessment. In this study, two new species, Paraleptomitella zunyiensis sp. nov. and P. reticula sp. nov., from the Cambrian Niutitang biota of Zunyi, Guizhou are described. These specimens not only exhibit the typical two-layered leptomitid skeletal architecture with monaxonal spicules, but they also demonstrate the presence of hexactine-based spicules (or their derived forms). This distinct spicular combination, particularly the occurrence of hexactine-based spicules (or their derived forms), may indicate the phylogenetic affinities of these sponges with the Hexactinellida rather than the Demospongiae. These new findings provide critical evidence for reevaluating the systematic position of Leptomitidae within Porifera and offer new insight into the origin and evolution of the body plans of early sponges.

国家自然科学基金项目(42262003, 42330209)和贵州省科技计划项目(ZD[2025]100, ZSYS[2024]002)联合资助