A remarkable new species of the millipede genus Trachyjulus Peters, 1864 (Diplopoda, Spirostreptida, Cambalopsidae) from Thailand, based both on morphological and molecular evidence

Recovery of the family status of Pericambalidae Silvestri, 1909, stat. nov. (Diplopoda: Spirostreptida: Cambalidea), with a revision of the genera and species from China

The millipede subfamily Pericambalinae Silvestri, 1909 is poorly understood and the taxonomic status remains controversial. Pericambalinae was regarded as either a subfamily of Cambalopsidae or an independent family. To address this issue, we conducted a molecular phylogenetic analysis and a morphological revision, and the genera and species from China are also revised. The results support the recovery of the family status, Pericambalidae, stat. nov. The morphological differences between Bilingulus Zhang & Li, 1981 and Parabilingulus Zhang & Li, 1981 are shown to be caused by post-embryonic development (anamorphosis and non-systemic metamorphosis) and both of these should be junior synonyms of Pericambala Silvestri, 1909 (Pericambala = Bilingulus, syn. nov. = Parabilingulus, syn. nov.). Three new combinations are proposed: Pericambala simplicia (Mauriès & Nguyen Duy-Jacquemin, 1997), comb. nov., Pericambala aramula (Zhang & Li, 1981), comb. nov. and Pericambala sinica (Zhang & Li, 1981), comb. nov. The mature specimens of Pericambala simplicia, comb. nov. and Pericambala aramula, comb. nov. were collected from the type localities and are described for the first time. A new species, Pericambala cordata, sp. nov. is described. After revision, Pericambalidae contains two genera and six species with one genus and four species recorded from China. Due to a deficiency in outgroup sampling, the phylogenetic status of Pericambalidae in the suborder Cambalidea remains uncertain. Variation of the gnathochilarium in Cambalidea is discussed and a key to the species of Pericambala in China is also provided. This research lays a foundation for further revision of Cambalidea in the future. ZooBank: urn:lsid:zoobank.org:pub:BDA46BCE-102B-45FE-A963-47F029A09E76.

Comparative morphological study of the gnathochilarium of millipedes of the suborder Cambalidea (Juliformia: Spirostreptida) assessed by discrete and morphometric character approaches

Phylogenetic relationships of the suborder Cambalidea have been a well-known focus of discussion over the past 100 years. The most recent approach to the suborder is based on the morphology of the sexual structure of males and of the gnathochilarium. The phylogenetic interpretation of the gnathochilarium has been especially criticized due to the poorly understood evolution of its components since no hypothesis of homology has been put forward. This work provides a comparative study of characters of the gnathochilarium. Twenty-one characters are proposed and optimized for 34 terminals from the orders Julida and Spirostreptida. Two datasets were analysed on the basis of whether the sclerite duplomentum corresponds to a mentum fused to a promentum or only to an elongated mentum (promentum being absent). Concatenated analyses were performed with both discrete and morphometric characters to verify the variation in shape of the mentum. In all topologies obtained, Cambalidea were recovered as paraphyletic in terms of the suborder Spirostreptidea. Through constrained searches, Cambalidae, Cambalopsidae and Iulomorphidae were not recovered, while Pseudonannolenidae were recovered only when Physiostreptinae were excluded. The morphological evidence indicates the convergence of the gnathochilarium in Spirostreptidea and in some members of Cambalidea, with independent reversions of the promentum.

Review of the millipede genus Malayorthomorpha Mršić, 1996 (Diplopoda, Polydesmida, Paradoxosomatidae), with descriptions of two new species from Thailand and a key to its species

The millipede genus Malayorthomorpha Mršić, 1996, so far monospecific and previously known only from Park Belum, Perak State, northern Malaysia, is recorded from a mountain in Betong District, Yala Province, southern Thailand for the first time, being represented there by two new species: M.halabala sp. nov. and M.hulutbeeda sp. nov. Both new species are found to occur syntopically and can be assumed as narrowly endemic to the Titiwangsa Mountain Range which begins in southern Thailand, crosses the Malaysian border, and extends into east and west coast regions of the Malay Peninsula. In addition, the generic diagnosis is slightly updated, and a key to all three species is provided.

Revision of the javanicus species group of the millipede genus Glyphiulus Gervais, 1847, with descriptions of five new species from China (Diplopoda, Spirostreptida, Cambalopsidae)

The javanicus-group of Glyphiulus is re-assessed and its Chinese component species are presently divided between the following two newly-circumscribed species groups, i.e. the formosus- and the sinensis-group. The two can be differentiated, based on the diagnostic characters of the first pair of legs in the male. In addition, metatergal crests being complete and the carinotaxy formula on the collum being I-III+P+M are only characteristic of the formosus-group. A molecular phylogeny of the genus, based on DNA sequencing of four gene fragments of four genes, allows for Glyphiulus to be recovered as a monophyletic group, the phylogenetic relationship being ((Clade A, Clade B), Clade C). Molecular evidence is fully congruent with the morphological one. In addition, based on barcoding data, interspecific p-distances between Glyphiulus species amount to 11.2-24.9%, vs. 0-8.2% for intraspecific p-distances. Five new species of Glyphiulus, all cavernicolous, are described from China: G.sinuatoprocessus Zhao & Liu, sp. nov., G.conuliformis Zhao & Liu, sp. nov. (both from Guangdong Province), G.xiniudong Zhao & Liu, sp. nov., G.scutatus Zhao & Liu, sp. nov. and G.portaliformis Zhao & Liu, sp. nov. (all three from Guangxi Zhuang Autonomous Region). The known Chinese species of the formosus-group appear to mainly be confined to the South China region.

The Oriental millipede genus Nepalella Shear, 1979, with the description of a new species from Thailand and an updated key (Diplopoda, Chordeumatida, Megalotylidae)

The Oriental genus Nepalella is reviewed, rediagnosed and shown to comprise 28 species, including N.siamensissp. nov. from southeastern Thailand. All Nepalella species are keyed, and their distributions mapped, being highly localized and mainly allopatric. Unlike most congeners, which are largely confined to subtropical environments (including montane to high-montane conditions, up to 3800 m a.s.l.) or karst caves (eight species, all in southern China alone), the new species is the southernmost in the distribution area of the entire genus, also being among the very few (four) that are restricted to lowland, purely tropical habitats.

The giant pill-millipede genus Zephronia Gray, 1832 from Thailand, with a redescription of Z.siamensis Hirst, 1907 and descriptions of three new species (Diplopoda, Sphaerotheriida, Zephroniidae)

Material of the giant pill-millipede genus Zephronia Gray, 1832 recently collected from Thailand contains three new species: Zephroniaenghoffisp. nov., Zephroniagolovatchisp. nov., and Zephroniapanhaisp. nov. The first Zephronia species recorded for Thailand, Z.siamensis Hirst, 1907, is also redescribed based on new specimens collected both from the type locality in Chonburi Province and from neighboring areas. Morphological characters of all new species, Z.phrain Likhitrakarn & Golovatch, 2021, and Z.siamensis are illustrated, and a distribution map of the confirmed Zephronia species occurring in Thailand is also provided.

Two new species of the millipede genus Glyphiulus Gervais, 1847 (Diplopoda, Spirostreptida, Cambalopsidae) from caves in northern Thailand

Two new species of the genus Glyphiulus Gervais, 1847 are described and illustrated. The first species, G.longus sp. nov., is the second species of the javanicus-group to be found in Thailand. It resembles G.guangnanensis Jiang, Guo, Chen & Xie, 2018, from southern China, but is distinguished by a smaller size and the carinotaxic formula of the collum, combined with ♂ legs 1 bearing very strongly reduced telopodites, the anterior gonopods showing a pair of very long and slender apicomesal processes, and the denser plumose and stout flagella of the posterior gonopods. The second species, G.promdami sp. nov., the fifth member of the granulatus-group in Thailand, seems to be particularly similar to G.subbedosae Likhitrakarn, Golovatch & Panha, 2017, from Laos. However, it can be distinguished from the latter species mainly by showing a uniformly yellow collum and the posterior gonopod coxite bearing several strong setae in median and lateral views, coupled with the anterior gonopod coxosternum being microsetose in the anterior and medial parts in caudal view. An identification key to, and a distribution map of, all seven Glyphiulus species currently known to occur in Thailand are also provided.