Deep in the mountain forests of western China, a group of many-legged creatures has been hiding a taxonomic secret for more than nine decades. A new integrative study, published in the journal Zoosystematics and Evolution, has dismantled the millipede genus Mandarinopus, a name erected in 1933 and treated ever since as a distinct branch of the flat-backed millipede family Paradoxosomatidae. By combining fresh field collections from the very localities that gave these animals their names with a four-gene phylogenetic analysis, researchers have shown that Mandarinopus is not a coherent evolutionary lineage at all. Instead, its species are scattered deep inside the older genus Kronopolites, described by Carl Attems in 1914, and the genus name must now be retired as a junior synonym.
The problem began with morphology, the traditional backbone of millipede classification. Verhoeff separated Mandarinopus from the similar and geographically overlapping Kronopolites largely on the basis of the gonopods, the modified male copulatory legs that millipede taxonomists rely on heavily because their intricate shapes often differ between species. In Mandarinopus, the two key gonopodal structures, the solenomere and the solenophore, were described as less curved and more complex than in Kronopolites. Verhoeff also pointed to a sternal cone between the fourth pair of legs and, in the type species Mandarinopus gracilipes, a thorn-like distofemoral process on the gonopodal femorite. These characters proved highly subjective in practice, and generations of taxonomists argued back and forth: Attems briefly sank the genus into Sundanina in 1937, Jeekel reinstated it in 1968 and speculated about a link with the genus Oxidus, and Golovatch expanded it in 2019 by moving in several species from Kronopolites and the long-enigmatic Orthomorpha corticina.
To cut through this ambiguity, the research team assembled topotypic material, specimens collected at or near the original type localities, for all five nominal species of Mandarinopus, together with eight representative species of Kronopolites including its type species Kronopolites svenhedini. Fieldwork took them from the Baishuijiang River area of Gansu Province, where gracilipes was first found, to high-elevation sites in Yunnan and Sichuan, including Hutiaoxia at 2,420 meters and the Dajudeng area of Laojunshan at 2,650 meters. Specimens were preserved in 75 percent ethanol, photographed both alive with a macro camera rig and in the lab under a Leica M205 MCA stereomicroscope, and deposited in the National Resource Center for Chinese Materia Medica in Beijing. DNA was extracted from leg tissue and sequenced on an Illumina NovaSeq platform, with mitochondrial genomes recovered using GetOrganelle and ribosomal RNA genes recovered using HybPiper.
The molecular dataset concatenated four markers, the mitochondrial genes COI and 16S rRNA and the nuclear 18S and 28S rRNA genes, totaling 2,480 base pairs. Phylogenetic reconstruction under both maximum likelihood, using IQ-TREE with a million ultrafast bootstrap replicates, and Bayesian inference, using MrBayes with ten million generations, produced consistent topologies. The result was unambiguous in one crucial respect: all species of Mandarinopus and Kronopolites together form a single strongly supported clade, with bootstrap support of 100 percent and a posterior probability of 1.00. Within that clade, however, Mandarinopus fell apart. All species except the type formed one well-supported group, Clade A, while the type species M. gracilipes emerged as the sister of K. svenhedini, the type species of Kronopolites, with strong support. In other words, the two genus names point at intertwined lineages, and retaining Mandarinopus would leave Kronopolites paraphyletic, a situation modern taxonomy cannot accept.
The genetic distances reinforced the picture. Pairwise COI distances among the species of both former genera ranged from roughly 11 to 18.6 percent under the Kimura two-parameter model, while populations identified as Kronopolites corticinus from different localities in Yunnan differed by only 0.53 percent, a gulf between species-level and population-level divergence that cleanly separates the two scales of diversity. The team also tested Jeekel’s old hypothesis of a close relationship between Mandarinopus and Oxidus and found no support for it: the Kronopolites clade, now including all former Mandarinopus species, is clearly distinct from Oxidus, which moreover lacks the characteristic femoral fork of two processes on the gonopod that defines Kronopolites.
Morphological re-examination explained why the old classification had gone astray. The characters used to diagnose Mandarinopus turned out to be continuous with, and variable within, Kronopolites. The supposedly diagnostic curvature of the solenomere, for example, is comparable between the former Mandarinopus semirugosus and the unmistakable Kronopolites ramosus from Vietnam. More damning still, the distofemoral process, the femoral thorn that Verhoeff treated as a generic hallmark, proved unstable even within a single species: in K. corticinus, specimens from the same population differ in whether the process is present. When a character appears and disappears among individuals of one species, it cannot bear the weight of a genus-level distinction, and the authors concluded that the so-called Mandarinopus-type gonopod either evolved independently more than once or represents ancestral variation retained across the group.
The revision that follows is sweeping. All four valid species formerly placed in Mandarinopus are transferred to Kronopolites as new combinations: K. gracilipes, K. corticinus, K. semirugosus, and K. hirsutus. K. semirugosus, moved out of Kronopolites in 2019, is formally restored to it. The expanded genus now contains 18 recognized species distributed across China, Vietnam, Nepal, Thailand, and the Kashmir Himalaya. The study also resolved a long-suspected species-level synonymy: K. rugosus, described in 2013 from Yuzhuqingtian in Yunnan, is a junior synonym of K. corticinus, originally described by Attems in 1936 from an unspecified Yunnan locality. The traits Golovatch had used to separate the two, a distofemoral process and a mesal process on the apical branch of the solenophore, proved unreliable in the new material, and the near-zero COI divergence among populations confirmed that a single, widely distributed species is involved.
One of the study’s most instructive cases is K. hirsutus, the only species in the genus with a dense coat of setae covering its body. Its shaggy exterior had made it look superficially unlike its relatives, feeding uncertainty about its placement. The molecular data from newly collected topotypic specimens place it firmly within the Kronopolites clade, showing that the hirsute body surface is a species-specific autapomorphy, a unique derived trait of one lineage, rather than evidence of a separate genus. The authors draw a parallel with the genus Desmoxytes, where striking variation in the texture of the dorsal plates, the metaterga, occurs even within a single monophyletic lineage, a pattern repeated across unrelated clades of paradoxosomatid millipedes.
The broader lesson is one that integrative taxonomy has been delivering with increasing force: somatic traits that are evolutionarily labile and prone to convergence should never be the sole basis for drawing generic boundaries. Body texture, setation, and even aspects of gonopod shape can shift rapidly within lineages, producing look-alike structures in unrelated species and disguising close relatives behind superficial differences. Only by anchoring classification in evolutionary history, reconstructed here from topotypic material and multiple genetic markers, can names reflect true biological relationships. For the millipedes of western China, the result is a cleaner, more stable classification, with Kronopolites standing as a single, coherent, and now considerably richer genus, and a ninety-year-old name gracefully retired to the synonymy.
Subject of Research: Integrative taxonomy and phylogenetic revision of the millipede genera Mandarinopus and Kronopolites in western China
Article Title: The millipede genus Mandarinopus Verhoeff, 1933, is a junior synonym of Kronopolites Attems, 1914 ( Polydesmida , Paradoxosomatidae ), with a revision of the species based on integrated evidence
Article References: Xiong, Y., Chen, H., Huang, L., Jiang, X., & Jiang, C. (2026). The millipede genus Mandarinopus Verhoeff, 1933, is a junior synonym of Kronopolites Attems, 1914 (Polydesmida, Paradoxosomatidae), with a revision of the species based on integrated evidence. Zoosystematics and Evolution, 102(1), 271-283. https://doi.org/10.3897/zse.102.180695
Image Credits: AI Generated
Keywords: millipedes, taxonomy, Kronopolites, Mandarinopus, Paradoxosomatidae, phylogenetics, integrative taxonomy, COI, gonopods, China, new synonymy, species revision
News Source: Drew Townsend. (October 18, 2026). DNA evidence topples a 90-year-old millipede genus in western China. Scienmag.
