ON THE TAXONOMIC PROBLEM OF THE ABADIELLATRILOBITES

In the present paper,the method of"Q-mode cluster analysis"is used in a taxonomic study of 18 cranidia belonging to abadiellid trilobite genera(subgenera)of traditional early Cambrian age.The statistical measurement of similarity is incremental sum of error squares(ΔE). The author uses the variables in the eight quantitative ratio form(see table 1).The resemblance relation matrices of all specimens are formed through calculation of the increments of sum of error squares between those specimens(see table 2).Finally,the two-dimensional dendrogram is drawn by stepwise calculation(see text-fig.2).The dendrogram(text-fig.2)shows nine specific groups by the association line having a value of increments of sum of error squares 0.1.They correspond as follows:Group A(= Abadiella huoi)—containing 5 species:Parabadiella huoi Zhang,1966(1),Parabadiella shaanxiensis Zhang and Lin,1980(7),Parabadiella obscurata Zhang and Lin,1980(9),Parabadiella(Danangouia)quadrata Chen,1985(3),Parabadiella tenuilimbata Zhang and Lin,1980(8).Group B(=Abadiella elegans)—containing 2 species:Guangyuanaspis elegans Lee,1978(14),Guangyuanaspis fandianensis Zhang and Lin,1980(15).Group C(= Abadiella longmenshanensis)—containing only 1 species: Parabadiella longmenshanensis Lee,1978(11).Group D(= Abadiella yunnanensis)—containing 2 species:Parabadiella yunnanensis Luo,1981(17),Parabadiella zhongliangsiensis Chen,1985(6).Group E(=Abadiella elevata)—containing 2 species:Parabadiella elevata Lee,1978(12),Parabadiella conica Luo,1981(16).Group F(= Abadiella hanzhongensis)—containing 3 species:Parabadiella(Danangouia)transversa Chen, 1985(2), Parabadiella hanzhongensis Chen, 1985(4), Parabadiella nanzhengensis Chen,1985(5).Group G(= Abadiella modaoyaensis)—containing only 1 species: Guangyuanaspis modaoyaensis Chang and Qian,1974(13).Group H(= Abadiella shaanxiensis)—containing only 1 species too:Guangyuanaspis shaanxiensis Zhang and Lin,1980(10).Group I(= Abadiella wudingensis)—containing also only 1 species:Guangyuanaspis wudingensis Zhang and Lin,1980(18).Through the application of combined cluster analysis with traditional qualitative analysis in the study of 18 species of abadiellid trilobites in this paper,the opinion on lumping and transferring the studied species is proposed(see table 3).

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