A new jewel-like species of the pill-millipede genus Sphaerobelum Verhoeff, 1924 (Diplopoda, Sphaerotheriida, Zephroniidae) from Thailand

A new species of the giant pill millipede genus Sphaerobelum is described: Sphaerobelumturcosasp. nov. from the northeastern part of Thailand. Species delimitation is based on morphological characters and COI sequence data. The new species can be clearly discriminated from congeners by its greenish-blue body color, the face mask-like appearance of the thoracic and anal shields jointly when rolled up, and the combination of the following four characters: (1) the coxa of the second leg laterally with a sharp and long process, (2) the tarsi of legs 4-21 with 6-7 ventral spines, (3) the anterior telopods consisting of four conspicuous telopoditomeres, and (4) the immovable, slender (not strongly humped) and distally curved finger of the posterior telopods without a membranous spot. The interspecific COI sequence divergence between the new species and other Sphaerobelum species ranges from 17% to 23% (mean 20%). The intergeneric COI sequence divergence between the new species and Zephronia species ranges from 18% to 21% (mean 20%). The relationships among Sphaerobelum and Zephronia species based on the COI sequence data were not resolved in this study. Sphaerobelumturcosasp. nov. is restricted to limestone habitat in Loei province and is probably endemic for the Thai fauna.

Two new millipede species of the genus Coxobolellus Pimvichai, Enghoff, Panha & Backeljau, 2020 (Diplopoda, Spirobolida, Pseudospirobolellidae)

Two new millipede species of the genus Coxobolellus Pimvichai, Enghoff, Panha & Backeljau, 2020 from Thailand are described: Coxobolellussaratani sp. nov. from Loei Province and Coxobolellusserratoligulatus sp. nov. from Uttaradit Province. The descriptions are based on gonopod morphology and two mitochondrial gene fragments (COI and 16S rRNA). The phylogenetic mtDNA analysis assigned the two new species unequivocally to the consistently well-supported Coxobolellus clade, in which they form a fifth subclade that was well supported by maximum likelihood analysis of 16S rRNA, though neither by Bayesian inference nor by COI. The two new Coxobolellus species share four conspicuous gonopodal synapomorphies of the genus: (1) the protruding process on the coxae of the 3^rd (and sometimes 4^th) pair of male legs, (2) a large, triangular coxae on the 4^th-5^th pair of legs, (3) a short process of the preanal ring protruding as far as, or slightly beyond, the anal valves, and (4) the posterior gonopod telopodite divided into two parts, with a conspicuous pore opening at the mesal margin at the end of the coxal part of the posterior gonopod. Thus, the two new species provide further evidence of the well-defined monophyly of the genus Coxobolellus. Finally, the paper provides an updated morphological identification key to all currently described Coxobolellus species.

A new genus of Pseudospirobolellidae (Diplopoda, Spirobolida) from limestone karst areas in Thailand, with descriptions of three new species

A new genus of the millipede family Pseudospirobolellidae, Siliquobolellusgen. nov., is described from limestone mountains in Thailand, based on three new species, viz. Siliquobolellus amicusdraconisgen. et sp. nov. from Uthaithani Province, Siliquobolellus constrictusgen. et sp. nov. from Prachuap Khiri Khan Province and Siliquobolellus prasankokaegen. et sp. nov. (type species) from Lampang Province. The descriptions are based on gonopod morphology and mitochondrial DNA data (COI barcodes). The COI barcodes grouped the three new species in a well-supported Siliquobolellusgen. nov. clade. The mean interspecific COI sequence divergence among the three new species was 12% (range: 8–15%). The mean intergeneric COI sequence divergence between Siliquobolellusgen. nov., Coxobolellus Pimvichai, Enghoff, Panha & Backeljau, 2020, and Pseudospirobolellus Carl, 1912 was 19% (range: 14–23%). Three conspicuous gonopodal synapomorphies differentiate Siliquobolellusgen. nov. from other pseudospirobollellid genera: (1) the telopodital part of the posterior gonopod forms a deep concavity, (2) the telopodite of the anterior gonopod is directed distad and does not reach the tip of the coxal part of the anterior gonopod, and (3) the tip of the anterior gonopod coxa is narrowed, curving mesad. As such, the monophyly of the new genus is well supported by both morphological and mitochondrial DNA data. A distribution map and an identification key to the species are provided.

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.

Genetic Diversity and Population Structure of Spirobolus bungii as Revealed by Mitochondrial DNA Sequences

Soil macrofauna, such as Spirobolus bungii, are an important component of ecosystems. However, systematic studies of the genetic diversity, population genetic structure, and the potential factors affecting the genetic differentiation of S. bungii are lacking. We performed a population genetic study of 166 individuals from the mountains to the south of the Yangtze River, north of the Yangtze River in Nanjing city, and near Tianjin city, in order to investigate the correlations between geographical distance and genetic diversity. A total of 1182 bp of COX2 and Cytb gene sequences of mitochondrial DNA, and 700 bp of the 18S rRNA gene sequence were analyzed. There were two haplotypes and one variable site in the 18S rRNA gene, and 28 haplotypes and 78 variable sites in the COX2 and Cytb genes. In this study, the 18S rRNA gene was used for species identification, and mtDNA (concatenated sequences with Cytb and COX2) was used for population genetic analysis. Structure cluster analysis indicated that the genetic structures of the different populations of S. bungii tended to be consistent at small geographical scales. Phylogenetic trees revealed that the haplotypes were clearly divided into three branches: the area south of the Yangtze River, the area to the north of the Yangtze River in Nanjing, and the area in Tianjin. Large geographical barriers and long geographical distance significantly blocked gene flow between populations of S. bungii. Our results provide a basic theoretical basis for subsequent studies of millipede taxonomy and population genetic evolution.

Redescription of the giant Southeast Asian millipede Spirobolus macrurus Pocock, 1893 and its assignment to the new genus Macrurobolus gen. nov. (Diplopoda, Spirobolida, Pachybolidae)

A new genus of the millipede family Pachybolidae from Southeast Asia is described: Macrurobolusgen. nov., with Spirobolusmacrurus Pocock, 1893 as type species. This latter species is DNA barcoded (COI) and redescribed based on male morphological characters, which hitherto were unknown. The new genus differs from other pachybolid genera by having (1) the preanal ring process long and protruding beyond the anal valves and (2) the anterior gonopod telopodite distally abruptly narrowed, forming an extremely long, slender, elevated process curved caudad. Given that Macrurobolusgen. nov. is a monotypic genus, it is aphyletic and thus requires further taxonomic revision.

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.