Myrioneuron R. Brown ex J. D. Hooker in Bentham & Hooker (1873: 69) comprises about eight species of the family Rubiaceae and it is distributed in East Himalaya to South China (Govaerts et al. 2011). Although it was occasionally treated as a synonym of Mycetia Reinwardt (1825: 9) (Bakhuizen 1975) or Keenania J. D. Hooker (1880: 101) (Van Steenis 1987, Robbrecht 1988), most botanists accepted it as a distinct genus (Kurz 1877, Hooker 1880, Schumann 1891, Pitard 1923, Merrill 1942, Bremekamp 1952, Deb 1996, Lo 1999, Wright 1999, Kress et al. 2003; Chen & Taylor 2011, Govaerts et al. 2011). Most recently, however, a molecular phylogenetic study revealed that Myrioneuron and Mycetia are non-monophyletic and intermixed, and therefore both taxa were combined to represent a monophyletic genus and Mycetia was accepted as its generic name (Ginter et al. 2015). In the study, they published nine new combinations, including Mycetia angustifolia (J. D. Hooker 1880: 97) Razafim. & B. Bremer in Ginter et al. (2015: 293). However, this name is illegitimate because it is a later homonym of Mycetia angustifolia Ridley (1923: 68), in accordance with Article 53.1 of the ICN (McNeil et al. 2012).

A new species exhibiting cauliflory within the tribe Argostemmateae (Rubiaceae), Mycetia saxicola Z.Q. Song & D.X. Xu, is described and illustrated from limestone areas in Yunnan, China. Our comprehensive study, which includes literature reviews, field and herbarium morphological observations, and molecular phylogenetic analyses of five plastid DNA regions, reveals that M. saxicola is closely related to M. fangii K.J. Yan & Z.Q. Song. Morphologically, both species share several key features, including cauliflorous inflorescences, few flowers per inflorescence, eglandular bracts and bracteoles, short corolla tubes, and calyx lobes much shorter than the corolla. However, M. saxicola can be readily distinguished from M. fangii by its limestone habitat, subcoriaceous leaves, linear stipules, very short pedicels and peduncles, and a calyx bearing two sessile, deciduous glands on each sinus. Additionally, this paper provides illustrations of six other relevant species of Mycetia to facilitate further taxonomic comparisons.

Verdesmummenglaense (C. Chen & X. J. Cui) H. Ohashi & K. Ohashi is a rare species in the tribe Desmodieae (Fabaceae) from Southwest China. The morphological observation shows that the species has minute capitate stigma and ebracteolate calyces, which are entirely different from the funnel-shaped stigma and bracteolate calyces of the genus Verdesmum H. Ohashi & K. Ohashi, but are consistent with those of the genus Hylodesmum H. Ohashi & R. R. Mill. The generic placement of V.menglaense within Hylodesmum was further supported by molecular evidence. Therefore, this species should be returned to Hylodesmum as H.menglaense (C. Chen & X. J. Cui) H. Ohashi & R. R. Mill. A full description including floral characters, a colour plate and a distribution map are first provided here for this species. After excluding the solo representative in China, Verdesmum should be removed from the record in Flora of China.

A key diagnostic feature of the genus Mycetia is its berry-like fruits, which distinguish it from its capsular-fruited relatives in the tribe Argostemmateae. However, the fruit character of Mycetia hainanensis H.S.Lo has long remained uncertain, as the species was previously known only from flowering specimens. Our rediscovery of this species at the type locality has now resolved this uncertainty. We found that M. hainanensis produces fleshy capsules that open via an apical operculum and flowers with a corolla tube shorter than 4 mm long. This finding first prompted a morphological re-evaluation, which indicated that the species aligns more closely with the genus Mouretia . Subsequent molecular phylogenetic analyses of plastid and nuclear DNA data robustly supported this hypothesis, placing the species within Mouretia . Given the congruent evidence from both morphology and molecular phylogeny, we propose the transfer of M. hainanensis to Mouretia , along with a complete morphological description. As part of this revision, we also provide keys to all genera in the Argostemmateae and to all species in Mouretia , along with a distribution map of the genus.

Phylogenomics with dense taxon sampling offers a powerful means to resolve taxonomic and phylogenetic uncertainties. Hylodesmum is a legume genus with an East Asian (EA)–Eastern North American (ENA) disjunct distribution; however, its phylogeny and delimitation from Monarthrocarpus and Verdesmum remain uncertain. Here, we employed plastid genomes, nuclear ribosomal DNA, and 353 low‐copy nuclear genes to reconstruct the phylogeny of all recognized taxa across these genera. Our analyses consistently recover Verdesmum as nested within Hylodesmum , whereas Monarthrocarpus is distantly related. Within Hylodesmum , two major clades were recovered, which are better defined by flower color and leaf margin than by traditional morphological traits. Cytonuclear incongruence in the H. podocarpum and H. laxum complexes suggests likely chloroplast capture. Biogeographic reconstruction supports an “out of Himalaya‐Hengduan Mountains” origin for Hylodesmum , with a late Miocene dispersal to North America ( ca . 7.35 Ma), followed by two back‐dispersals to Asia ( ca . 5.67–4.98 Ma). This study reveals a complex history of bidirectional dispersal, likely facilitated by mammals, in an EA–ENA disjunct genus and provides a new phylogenetic framework for the taxonomic revision of Hylodesmum, recognizing 18 species within two sections.