The International Subcommision on Cambrian Stratigraphy (ISCS) has undertaken an effort to divide the Cambrian System into four series and ten stages, among which the second series, as well as the second, third, fourth and tenth stages have long remained unnamed and poorly constrained. The GSSP proposal for provisional Series 3 and Stage 5, based on the Wuliu-Zengjiayan section near Balang village, Jianhe, Guizhou, South China, was ratified on June 21, 2018 and was named Miaolingian Series and Wuliuan Stage. Other five stages, the Fortunian, Drumian, Guzhangian, Paibian and Jiangshanian, were formally defined by GSSPs (Peng et al., 2012).

Searching GSSP for the provisional Stage 4, Cambrian Series 2 is underway in the Jiaobang section, lying also near Balang village, Jianhe County. The section contains a continuous sequence of the Cambrian Series 2 with, in ascending stratigraphic order, the Bianmachong, Balang, “Tsinghsutung” and the lowermost part of the Kaili formations. A large collection of trilobites from the Balang and “Tsinghsutung” formations has provided an excellent fossil record to establish a new trilobite-based zonation with three new zones proposed below.

Oryctocarella duyunensis Zone. This zone occupies the lower part of the Balang Formation and contains Oryctocarella duyunensis, Duyunaspis duyunensis, Changaspis microtype, Redlichia (Pteroredlichia) chinensis, and Probowmania balangenus. Oryctocarella duyunensis makes its first appearance at 1 m above the base of the Balang Formation (Figs. 1-2,3e) (Zhao et al., 2017).

Arthricocephalus chauveaui Zone. This zone occupies the middle-upper part of the Balang Formation through the middle-upper part of the “Tsinghsutung Formation” and includes Arthricocephalus chauveaui (Haliplanktos jishouensis), Arthricocephalus xinzhaiheensis, Oryctocarella duyunensis, Oryctocarella balangensis, Duyunaspis duyunensis, Changaspis microtype, Redlichia (Pteroredlichia) murakammi, Probowmaniabalangensis, Olenoides cf. hubeiensis, and Olenoides constrictus; In total, this trilobite Zone contains 7 genera and 10 species. Arthricocephalus chauveaui makes its first appearance at 85.8 m above the base of the Balang Formation (Figs. 1-2, 3a-b, 3d, 3f) (Peng et al., 2015).

Protoryctocephalus arctiaus Zone. This zone occupies the middle-upper part of the “Tsinghsutung” Formation and contains Protoryctocephalus arctiaus, Protoryctocephalus balangensis, Duyunaspis duyunensis, Redlichia (R.) nobilis [=Redlichia (R.) guizhouensis], Burlingia balangensis, Panxinella angustilimbata Dinesus panxinensisand a large number of ptychopariids, viz., Nangops danzhaicnsis, Balangcunaspis cransversu, Mufushania cf. nakingensis, Eosoptychoparia gaodongensis, Eosoptychoparia sp. cf. yunnanensis, Olenoides constrictus, Olenoides cf. hubeiensis. This is also a trilobite diverse zone, having 15 genera and 18 species in total. Protoryctocephalus arcticus makes its first appearance at 162.2 m above the base of “Tsinghsutung” Formation (Figs. 1, 3c).

Further work is necessary in the following years to erect the new Stage 4. So far, these three new trilobite zones show us that either the FAD of Oryctocarella duyunensis or FAD of Arthricocephalus chauveaui could be used to define the base of provisional Stage 4 (Peng et al., 2017). This suggestion is base on the geographical record of these two species, which also are known from the Eoaagnostus roddyi-Arthricocephalus chauveaui Zone of Henson Gletscher Formation, North Greenland (Geyer & peel, 2011). Thus, an accurate correlation between South China and North Greenland can be done.