Jinia rosettea gen. et sp. nov.
Etymology. The generic name derives from the the Jindinshan formation, the strata where the fossil been found. Species name after rosette to describe the plate with its surrounding polygons are flower formed (Fig. 1a-d; S1).
Holotype. Guizhou Research Center for Palaeobiology (GRCP) 14001, Guizhou University. GRCP 14002, 14003 represent the developing states of the worms.
Locality and horizon. The specimens were collected from the lower mudstone of the Jindinshan Formation, Cambrian Stage 4, of Guizhou, South China.
Dignosis for genus and species. The body of the worm are made up of rings. Each ring boundary is defined by the annular furrows (Fig. 1b,c; 4a,b; S1). The linear arrange circular plates with apexes distribute on the two sides of the furrow (Fig. 1b; S1g). The furrows are consist of bi-serial oval formed polygons, named boundary cells. The surface of the epidermis dominant by 4–8 sides cell lattices (Fig. 1d; S1g). The boundary of the plates and cell lattices are zigzag formed (Fig. 1c, d; S1d).
The convergent evolution force several clades fall into a close morph space. The inter plate polygons have been found in the phosphatized epithelial fragments of Hadimopanella which named the micro plates and the boundary cells previously named as inter annular furrows [20, 21]. These structures have received less attention than the plate. The small specimens with a relatively narrow inter plate space and the space extends in the larger specimens (Figure S1). The specimen series interpreted as the developmental sequence of the J. rosettea. New inter plate cell lattices emerge (Figure S1). The developmental patterns are widely recorded in other early Cycloneuralia .
Meitis elegans gen. et sp. nov.
Etymology. The generic name derives from the the Meitan formation, the strata that the fossil been found. Species name after elegance.
Holotype. Guizhou Research Center for Palaeobiology (GRCP) 22001, Guizhou University (Fig. 1e).
Locality and horizon. The specimen was collected from the lower mudstone of the Meitan Formation, Early Ordovician (Florian), Guiyang city, South China.
Dignosis for genus and species. The body of the worm are made up of rings. Each ring boundary defined by the annular furrows (Fig. 1f,g; 4c,d). The annular furrows consist of rectangle polygons. The platelets distribute along the two sides of a row of rectangle polygons. The surface of the epidermis dominant by 6 sides cell lattices (Fig. 1f). The aspect ratio of the plate range from 1–2 and the apexes of the plates range from 1 to 3 (Fig. 1g).
The ornaments of the epidermis of the Ordovician worms  occupied a much wider morph spaces than that of their Cambrian counterparts. Meitis elegans gen. et sp. nov. share similarities with the plate outline of the 495-Myr‐old Palaeoscolex piscafumm and Gnmoscolex herodes from the lower Ordovician strata. All of them have distinct boundary zone of the rings [24, 25]. However, the plate apexes and distribution pattern of these species are remarkably different [24, 25].