#ZooKeys ZooKeys 1215: 235-257 (2024) DOI: 10.3897/zookeys.1215.130919 Research Article A new species of the pill millipede genus Rhopalomeris Verhoeff, 1906 (Diplopoda, Glomerida, Glomeridae) from Myanmar, and notes on Rhopalomeris carnifex (Pocock, 1889) Natdanai Likhitrakarn’™®, Sergei |. Golovatch?®, Ruttapon Srisonchai*®, Parin Jirapatrasilp®, Pichsinee Sapparojpattana™®, Ekgachai Jeratthitikul5®, Somsak Panha**®, Chirasak Sutcharit*® Oo ono FP WO DY — Program of Agriculture, Faculty of Agricultural Production, Maejo University, Chiang Mai 50290, Thailand Institute of Ecology and Evolution, Russian Academy of Sciences, Leninsky pr. 33, Moscow 119071, Russia Department of Biology, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand Animal Systematics and Molecular Ecology Laboratory, Department of Biology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand Academy of Science, The Royal Society of Thailand, Bangkok 10300, Thailand Corresponding author: Chirasak Sutcharit (jirasak4@yahoo.com; chirasak.s@chula.ac.th) OPEN Qaccess Academic editor: Pavel Stoev Received: 1 July 2024 Accepted: 29 August 2024 Published: 16 October 2024 ZooBank: https://zoobank. org/63D44DED-ABOD-4762-99A9- CC64B9EB8AE4 Citation: Likhitrakarn N, Golovatch Sl, Srisonchai R, Jirapatrasilp P Sapparojpattana P, Jeratthitikul E, Panha S, Sutcharit C (2024) A new species of the pill millipede genus Rhopalomeris Verhoeff, 1906 (Diplopoda, Glomerida, Glomeridae) from Myanmar, and notes on Rhopalomeris carnifex (Pocock, 1889). ZooKeys 1215: 235-257. https://doi. org/10.3897/zookeys.1215.130919 Copyright: © Natdanai Likhitrakarn et al. This is an open access article distributed under terms of the Creative Commons Attribution License (Attribution 4.0 International - CC BY 4.0). Abstract The taxonomy of the pill millipede genus Rhopalomeris Verhoeff, 1906, which is restrict- ed to Indochina and currently comprises six described species, is refined and updated. An integrative taxonomic approach was employed that combines morphological exam- ination with DNA barcoding using the cytochrome c oxidase subunit | (COI) gene for species identification and delineation. The first objective was to confirm the identity of Rhopalomeris carnifex (Pocock, 1889), a charismatic species known as the “candy pill millipede” due to its vivid coloration, based on specimens collected near the type locality in Myanmar. The second objective was to describe a new species, Rhopalomeris nigroflava Likhitrakarn, sp. nov., discovered in Linno Gu, Kayin State, Myanmar. This new species is distinguished by its small body size (5.1-9.7 mm long) and yellow body with contrasting brown to blackish markings on certain terga. In addition, the position of the telopod syncoxital lobe relative to the lateral syncoxite horns separates it from other Rhopalomeris species. The interspecific divergence between R. nigroflava Likhitrakarn, sp. nov. and other congeners ranges from 10.85% to 16.13%, based on uncorrected COl p-distances, while the intraspecific divergence was 0%-7.44%. A distribution map of and a revised identification key to all known species of Rhopalomeris are also provided. Key words: Biodiversity, candy pill millipede, key, systematics, taxonomy Introduction The Oriental genus Rhopalomeris Verhoeff, 1906 consists of only six species, all of which are restricted to Indochina (Golovatch et al. 2011; Golovatch 2017). The distribution range of this genus extends from the southern peninsular regions (Malaysia and Myanmar) to the North, encompassing Thailand and reaching as far as northern Vietnam (Fig. 1). All species except for R. carnifex 235 Natdanai Likhitrakarn et al.: A new Rhopalomeris species from Myanmar (Pocock, 1889) show narrow distributions, while R. carnifex has been reported from a broader area that includes both Myanmar and Thailand (Fig. 1). The genus Rhopalomeris belongs to the family Glomeridae. A total of 43 spe- cies of Glomeridae have so far been identified in Indochina and classified into six genera: Annameris Verhoeff, 1915 (two species), Hyleoglomeris Verhoeff, 1910 (23 species), Hyperglomeris Silvestri, 1917 (eight species), Rhopalomer- is Verhoeff, 1906 (six species), Peplomeris Silvestri, 1917 and Tonkinomeris Nguyen, Sierwald & Marek, 2019 (one species each) (Likhitrakarn et al. 2014, 2023a, 2023b, 2024; Golovatch 2017; Golovatch and Semenyuk 2016; Nguyen et al. 2019, 2021). Two unique morphological characters could be used to distinguish Rhopalomeris from the other glomerid genera: (1) antennomere 6 conspicu- ously enlarged, axe-shaped, exceeding the size of antennomeres 3-5 com- bined; (2) antennomere 7 also wide, topped by a disc-shaped antennomere 8 with numerous sensory cones, vs usually only four apical cones in other genera (except Peplomeris). A well-known Rhopalomeris species is R. carnifex, commonly referred to as the “candy pill millipede” or “rainbow candy pill millipede” because of its striking and vibrant patterns (Fig. 2). This characteristic has contributed to its popularity among exotic pet traders worldwide (https://www.reddit.com/r/mil- lipnedes/comments/xdrsr0/candy_pill_millipede/; https://undergroundreptiles. com/product/candy-pill-millipede/; https://www.exotic-pets.co.uk/candy-red- pill-bug.html; https://thespidershop.co.uk/product/rhopalomeris-carnifex/). The present study employs an integrative taxonomic approach, combining both traditional morphological examinations and DNA barcodes derived from a fragment of the COI gene. The aims of this study are to re-evaluate the taxono- my of R. carnifex by examining specimens collected from Koh Kala, Tanintharyi Division, Myanmar, and to describe a new species discovered at Linno Gu, Kayin State, Myanmar. We also provide a comprehensive distribution map and a re- vised identification key to all species currently recognized in this genus. Material and methods Morphological studies The new material was collected in Myanmar in 2015 and 2016 by SP and mem- bers of the Animal Systematics Research Unit, Chulalongkorn University, as well as by a French collecting team led by Louis Deharveng, of the Muséum na- tional d’Histoire naturelle (MNHN), Paris, France. The locations of the collecting sites were recorded by GPS using a Garmin GPSMAP 60 CSx based on the WGS 84 datum, and all coordinates and elevations were double-checked using Goo- gle Earth. The collected specimens were euthanized using a two-step method following the AVMA Guidelines for the Euthanasia of Animals (AVMA 2013) and preserved in 90% (v/v) ethanol for morphological and molecular studies. After 24 h, the ethanol was replaced with 95% (v/v) ethanol to prevent defensive chemicals from interfering with DNA extraction. The holotype and most paratypes are housed in the Museum of Zoology, Chulalongkorn University (CUMZ), Bangkok, Thailand. A few paratype dupli- cates have been deposited in the MNHN, Paris, France. The specimens were ZooKeys 1215: 235-257 (2024), DOI: 10.3897/zookeys.1215.130919 236 Natdanai Likhitrakarn et al.: A new Rhopalomeris species from Myanmar N 100! 200km Figure 1. Distributions of all seven currently known Rhopalomeris species. Open trian- gles Rhopalomeris sauda Nguyen, Sierwald & Marek, 2019; filled circle Rhopalomeris nagao Nguyen, Nguyen & Eguchi, 2021; inverted filled triangle Rhopalomeris tonkinensis Silvestri, 1917; crossed circle Rhopalomeris nigroflava sp. nov.; filled squares Rhopalom- eris carnifex (Pocock, 1889); red square Elphinstone Island; green square Kala Island; open circle Rhopalomeris variegata Golovatch, 2016; open diamond Rhopalomeris mo- nacha Silvestri, 1917. examined, measured, and photographed using a Nikon SMZ 745T trinocular stereo microscope equipped with a Canon EOS 5DS R digital SLR camera. Dig- ital photographs were processed and modified using Adobe Photoshop CS5. The line drawings were based on photographs captured under a stereo micro- scope equipped with a digital SLR camera. The terminology used to describe the morphological structures is consistent with that applied in the most recent publications (Golovatch et al. 2006; Golo- vatch 2017; Likhitrakarn et al. 2024). In the catalogue sections, D stands for the original description and subse- quent descriptive notes; K for the appearance in a key; L for the appearance ina species list; M for a mere mention; MI for molecular information; and R for new subsequent records. ZooKeys 1215: 235-257 (2024), DOI: 10.3897/zookeys.1215.130919 237 Natdanai Likhitrakarn et al.: Anew Rhopalomeris species from Myanmar DNA extraction, PCR amplification, and sequencing Total genomic DNA was extracted from the legs and part of the thoracic tissues using a DNA extraction kit for animal tissue (NucleoSpin Tissue Extraction Kit, Macherey-Nagel, Germany) following the standard procedure. The mitochondri- al cytochrome c oxidase subunit | gene (COI: 660 bp) fragments were amplified using the primers LCO1490 and HCOoutout (Folmer et al. 1994; Schulmeister et al. 2002) or LoboF1 and LoboR1 (Lobo et al. 2013) using a T100™ thermal cycler (BIO-RAD) with a final volume 30 uL, DNA template 5 uL (15 uL EmeraldAmp GT PCR Master Mix, 1.5 uL each primer, 10 ng template DNA, and distilled water up to 20 uL total volume). Thermal cycling was performed at initial denaturation at 94 °C for 3 min, followed by 35 cycles of 94 °C for 30 s, annealing at 46 °C for 60 s in both primer sets, extension at 72 °C for 90 s, and final extension at 72 °C for 5 min. Amplification of the PCR products was confirmed by 1.5% (w/v) agarose gel electrophoresis before purification using MEGAquick-spinTM plus (Fragment DNA purification kit) and sequenced in both directions (forward and reverse) using an automated sequencer (ABI prism 3730XL). All nucleotide sequences obtained in this study have been deposited in the GenBank Nucleotide sequence database under the accession numbers PQ219547-PQ219550. The collecting localities and GenBank accession num- bers for each nominal species are listed in Table 1. Phylogenetic analyses The sequences were aligned using MEGA7 (Kumar et al. 2016). The final aligned dataset included 660 bp of the 61 COI sequences. The dataset included four sequences of Rhopalomeris that were newly obtained in this study and 57 se- quences retrieved from the GenBank database, including all available sequences of Rhopalomeris species from Vietnam and other countries, and species of other genera in the Glomeridae (Eupeyerimhoffia Brélemann, 1913, Glomeris Latreille, 1802, Hyperglomeris Silvestri, 1917, Peplomeris Silvestri, 1917, Hyleoglomeris Ver- hoeff, 1910, Tonkinomeris Nguyen, Sierwald & Marek, 2019, and Trachysphaera Heller, 1858) (Table 1). Sohaerobelum Verhoeff, 1924 and Zephronia Gray, 1832 (order Sphaerotheriida, family Zephroniidae) were used as distant outgroups. The best-fit substitution model was determined using PartitionFinder2 v. 2.3.4 (Lanfear et al. 2016) and used in subsequent phylogenetic analyses. The selected best-fit models for the three COI codon positions were SYM+I+G, GTR+l, and GTR+G, respectively. Phylogenetic relationships were reconstructed using two methods, maximum likelihood (ML) and Bayesian inference (BI) anal- ysis, and through the online CIPRES Science Gateway (Miller et al. 2010). The ML analysis was calculated in IQ-TREE 2.2.2.7 (Minh et al. 2020) with 10,000 replicates of ultrafast bootstrap approximation to assess topology bootstrap support (BS). The BI analysis was estimated in MrBayes 3.2.7 (Ronquist et al. 2012) using the Markov chain Monte Carlo technique (MCMC). The BI trees were run for 10 million generations using a random starting tree. The resultant trees were sampled every 1,000 generations and the values were used to esti- mate the consensus tree topology, bipartition posterior probability (bpp), and branch lengths, after discarding the first 25% of the obtained trees as burn-in. The average effective sample size (ESS) from the MCMC analysis were > 1,800 ZooKeys 1215: 235-257 (2024), DOI: 10.3897/zookeys.1215.130919 238 Natdanai Likhitrakarn et al.: Anew Rhopalomeris species from Myanmar Table 1. List of the species used for molecular phylogenetic analyses and their relevant information. * = paratype. Species Rhopalomeris carnifex Rhopalomeris nigroflava sp. nov. Rhopalomeris sauda Rhopalomeris nagao Hyleoglomeris tongkerdae Hyleoglomeris bomba Hyleoglomeris suwannakhuhensis Hyleoglomeris nigromaculata Hyleoglomeris dracosphaera Hyleoglomeris krasoon Hyleoglomeris hongkhraiensis Hyleoglomeris awaumi Hyleoglomeris insularum Hyleoglomeris japonica Hyleoglomeris lucida Hyleoglomeris sulcata Hyleoglomeris uenoi Hyleoglomeris halang Hyleoglomeris lobus Hyperglomeris bicaudata Hyperglomeris inkhavilayi Hyperglomeris simplex Peplomeris magna Voucher number GLOO016-1; GLO016-2 GLO093-1*; GLO093-2* IEBR-801; IEBR-706; IEBR-654; IEBR-533 IEBR-852; IEBR-854 MUMNH-GLOO71-1* MUMNH-GLO096-1* MUMNH-GLO039* MUMNH-GLO019-1%; MUMNH-GLO019-2%; MUMNH-GLO019-3* MUMNH-GLOO01-1%; MUMNH-GLO001-2%; MUMNH-GLO001-3*; MUMNH-GLO035-M 2%; MUMNH-GLO035-F4*; MUMNH-GLO035-M1*; MUMNH-GLO035-F3* MUMNH-GLO059* MUMNH-GLO029-2%; MUMNH-GLO029-3*; MUMNH-GLO031-3* EG20210711-227-01; EG20210711-227- 03; KS20210513-04; KS20210513-07 EG20201213-09 MS20210617-01; MS20210617-02; MS20210617-03 EG20210718-240-01; MS20210426-11 MS20210521B-05 $T20211028 IEBR-Myr898P; IEBR-Myr926 SVE-204; IEBR-653; IEBR-678 CUMZ-GLO004*; CUMZ-GLO007* CUMZ-GLO095/1*; CUMZ-GLO095/2* IEBR-605; SVE-102 IEBR-677; IEBR-656 ZooKeys 1215: 235-257 (2024), DOI: 10.3897/zookeys.1215.130919 Locality Myanmar Myanmar Vietnam Vietnam Thailand Thailand Thailand Thailand Thailand Thailand Thailand Japan Japan Japan Japan Japan Japan Vietnam Vietnam Laos Laos Vietnam Vietnam GenBank accession number COI PQ219547; PQ219548 PQ219549; PQ219550 MT 749398; MT749400; MT749401; MT749404 MT749411; MT749392 P493218 PP493219 PP493220 PP493221; PP493222; PP493223 PP493224; PP493225; PP493226; PP493227; PP493228; PP493229; PP493230 PP493231 PP493232; PP493233; PP493234 LC713407; LC713409; LC713416; LC713419 LC713421 LC713422; LC713423; LC713424 LC713425; LC713426 LC713428 LC713429 ON704753; ON704754 MT749391; MT749402; MT749406 0Q661871; 0Q661872 0Q661873; 0Q661874 MT 749403; MT749410 MT749405; MT749408 Likhitrakarn et al. Likhitrakarn et al. Likhitrakarn et al. Likhitrakarn et al. Likhitrakarn et al. Likhitrakarn et al. Likhitrakarn et al. Reference This study This study Nguyen et al. 2021 Nguyen et al. 2021 Kuroda et al. 2022b Kuroda et al. 2022b Kuroda et al. 2022b Kuroda et al. 2022b Kuroda et al. 2022b Kuroda et al. 2022b Kuroda et al. 2022a Nguyen et al. 2021 Likhitrakarn et al. 2023a Likhitrakarn et al. 2023a Nguyen et al. 2021 Nguyen et al. 2021 2024 2024 2024 2024 2024 2024 2024 239 Natdanai Likhitrakarn et al.: Anew Rhopalomeris species from Myanmar Species Tonkinomeris napoensis Trachysphaera costata Glomeris marginata Trachysphaera lobata Trachysphaera schmidtii Eupeyerimhoffia archimedis Sphaerobelum truncatum Zephronia laotica GenBank accession Voucher number Locality Somber Col Reference IEBR-804b; IEBR-804a Vietnam MT749396; Nguyen et al. 2021 MT749397 Tcost8-MK Slovakia KX467622 Mock et al. 2016 ZFMK-TIS-18977; France MG892125; Reip and Wesener 2018 ZFMK-TIS-2517216 MG892167 ZFMK:MYR TWO1 United; KJ408484 Wilbrandt et al. 2015 Kingdom ZFMK:MYR BGIMyr16 Croatia KJ408481 Wilbrandt et al. 2015 ZFMK:MYR1876 Italy KP205574 Oeyen and Wesener 2015 CUMZ:2010.18 Thailand JN885184 Wongthamwanich et al. 2012 ZFMK:MYR3502 Laos MK330977 Wesener 2019 for all parameters. The resulting tree was examined and edited using FigTree v. 1.4.3 (http://tree.bio.ed.ac.uk/software/figtree/, accessed on 28 February 2024). A clade was considered well supported if the ultrafast BS was = 95% and Bayesian bipartition posterior probability was = 0.95 (San Mauro and Agorreta 2010; Hoang et al. 2018). Intraspecific genetic distances within taxa that contained more than one in- dividual and interspecific genetic distances based on the COI sequences were also calculated using uncorrected p-distances, as implemented in MEGA7 (Kumar et al. 2016). Taxonomy Descriptions Family Glomeridae Leach, 1815 Genus Rhopalomeris Verhoeff, 1906 Rhopalomeris Verhoeff, 1906: 188 (D). Rhopalomeris — Silvestri 1917: 140 (D); Jeekel 1971: 17 (L); Mauriés 1971: 435 (M); 2007: 243 (M); Hoffman 1980: 68 (L); Golovatch et al. 2011: 1 (D); Golovatch and Semenyuk 2016: 413 (D, K); Nguyen et al. 2019: 292 (D, K); 2021: 259 (D). Diagnosis. The genus Rhopalomeris could be recognized through numerous apical sensory cones on the antennal tip, and antennomere 6 being particular- ly enlarged and rather strongly curved. In addition, the posterior telopods are rather strongly enlarged and stout, supplied with both prefemoral and femoral trichosteles. The femur has a distinctive and particular distocaudal process. The body is relatively large, with adults ranging from 11 to 20 mm in length. The body coloration is variable, but often useful for species identification. Type species. Glomeris carnifex Pocock, 1889, fixed under Art. 70.3 (ICZN 1999) in Golovatch et al. (2011), misidentified as Rhopalomeris bicolor (Wood, 1865) in the original designation by Verhoeff (1906). Other species included. Rhopalomeris monacha Silvestri, 1917; R. tonkinen- sis Silvestri, 1917; R. variegata Golovatch & Semenyuk, 2016; R. sauda Nguyen, Sierwald & Marek, 2019; and R. nagao Nguyen, Nguyen & Eguchi, 2021. ZooKeys 1215: 235-257 (2024), DOI: 10.3897/zookeys.1215.130919 240 Natdanai Likhitrakarn et al.: Anew Rhopalomeris species from Myanmar Remarks. The genus Rhopalomeris was originally typified by Verhoeff (1906) through the designation of Glomeris bicolor Wood, 1865 as the type species. However, this designation was based on specimens from Salanga Island (pres- ently known as Phuket Island, Thailand) housed in the Berlin Museum (currently Museum fiir Naturkunde Berlin; ZMB), and these specimens had been previous- ly identified by F. Karsch as G. bicolor. Although the type locality of G. bicolor is in Hong Kong (Wood 1865), Verhoeff (1906) followed Karsch’s identification, and refrained to introduce a new name to those specimens. Furthermore, Verhoeff (1906) compared the specimens from Phuket Island with G. carnifex, noting that several characteristics were similar to his speci- mens. He admitted that both might be two distinct species because of possible distinctions intelopods and the number of apical sensory cones on the antennae. Verhoeff also suggested to reclassify G. carnifex under the genus Rhopalomeris. Subsequently, Silvestri (1917) examined relevant material probably housed in the Zoological Survey of India, (formerly the Indian Museum). He synonymized G. bicolor sensu Verhoeff (1906) with R. carnifex var. pallida (Pocock, 1889) from Elphinstone Island, Mergui Archipelago, Myanmar, and redesignated R. carnifex from Tenasserim, Myanmar, as the type species. Finally, Golovatch et al. (2011) studied the specimens of G. bicolor sen- su Verhoeff (1906), from Salanga Island housed in the ZMB, and confirmed the identification of these specimens as R. carnifex. Golovatch et al. (2011) also synonymized the variety pallida with R. carnifex given the reason that the variety pallida was simply a color morph of R. carnifex, and validated that R. carnifex is the type species of Rhopalomeris, fixed under Art. 70.3 (ICZN 1999). Therefore, the millipede genus Rhopalomeris is currently known only from Myanmar, Thailand, Malaysia, and Vietnam, with a total of six nominal species involved (Fig. 1). Peplomeris was originally described as a subgenus of Rhopalomeris (Sil- vestri, 1917). However, it was later raised to a genus level by Mauriés (1971), who assigned this genus to the tribe Haploglomerini, whereas Rhopalomeris belongs to the tribe Trachysphaerini (Mauriés, 1971). Nguyen et al. (2019) pro- vided a comprehensive comparison among these two genera, highlighting key morphological differences among five Vietnamese glomerid genera. Peplomer- is is characterized by simple, elongated telopods, the presence of a prefemo- ral trichostele, and a reduced to missing femoral trichostele. In contrast, Rho- palomeris has antennomere 6 that is unusually large, and trichosteles present in both prefemur and femur of the telopods. The antennae of Rhopalomeris also have numerous apical sensory cones like in Peplomeris. Rhopalomeris carnifex (Pocock, 1889) Figs 2, 3 Glomeris carnifex Pocock, 1889: 290 (D). Type locality: Tenasserim. Glomeris carnifex var. pallida Pocock, 1889: 290 (D). Type locality: Elphinstone Island. Glomeris carnifex — Pocock 1890: 385 (R); Attems 1914: 138 (L); Hoffman 1980: 65 (M). Glomeris carnifex var. pallida — Attems 1914: 138 (L); Silvestri 1917: 143 (D). ZooKeys 1215: 235-257 (2024), DOI: 10.3897/zookeys.1215.130919 24] Natdanai Likhitrakarn et al.: Anew Rhopalomeris species from Myanmar “Glomeris” bicolor [non Wood, 1865] — Verhoeff 1910: 241 (M); Silvestri 1917: 143 (M); Hoffman 1980: 65 (M). Rhopalomeris carnifex — Silvestri 1917: 142 (D); Attems 1936: 194 (R); Enghoff 2005: 88 (R); Decker 2010: 24 (R); Golovatch et al. 2011: 6 (D); Golovatch and Semenyuk 2016: 411 (M, K); Likhitrakarn et al. 2017: 6 (L); Nguyen et al. 2019: 292 (M); 2021: 259 (M). Rhopalomeris carnifex var. pallida — Silvestri 1917: 143 (D); Attems 1936: 194 (L). Records in the literature. Myanmar, south Tenasserim (Pocock 1889); Malwoon in Tenasserim (Pocock 1890); Elphinstone Island (Pocock 1889); Moulmein (At- tems 1936); Taninthay Division, Tanintharyi Region, 9°56'20°N, 98°32'22’E, Tha- tay Kyun (= Pulo Ru, Ko Son) (Decker 2010). Thailand, Phuket Province, Salanga Island (= Phuket Island) (Verhoeff 1906; Enghoff 2005); Mueang Phuket Dis- trict, Ko Siray, 7°53'7°N, 98°26'14”E, 20-50 m a.s.|. (Decker 2010); Krabi Prov- ince, Krabi District, Nai Chong (Enghoff 2005); Ao Luk, 8°10'54°N, 98°50'30’E, 70 m; Ban Khlong Jilat, 8°05'18°N, 98°52'56°E, 60 m a.s.l.; near Saengphet Cave, 8°9'46°N, 98°53'12°E, 80 m; Ko Lanta District, Ko Lanta Island, 80 ma.s.l.; Phang Nga Province, Ko Yao District, Ko Yao Noi, 8°9'53°N, 98°37'20°E, 150 m a.s.l.; Thap Put District, Had Lek Beach, 8°37'N, 98°13'E, 10 m a.s.l.; Khao Lak-Lamru National Park, 8°37'N, 98°14'E, 30-40 m; Surat Thani Province, Ko Samui District, Samui Island, Khao Phlu, 10-500 m a.s.|.; Nam Tok Na Muang Forest Park, 30 m a.s.I.; Ko Pha Ngan District, Phangan Island, Than Sadet-Ko Phangan National Park, 9°44'7°N, 100°1'10’E, 320 m a.s.I. (Decker 2010). Ma- laysia, neighboring the Malay Peninsula (Verhoeff 1906). New material examined. MYANMAR - Tanintharyi Division * 2 <; Myeik, Kala Island; elev. 5m a.s.|.; 12°29'38"N, 98°30'53"E; 5 Apr. 2016; C. Sutcharit, W. Siri- wut, R. Srisonchai leg.; CUMZ-GLO016-1, 16-2. Description. Body length of unrolled specimens, 17.5-17.9 mm (3), width 8.9-9.1 (3). Color faded after 15 years of preservation in alcohol (Fig. 2A—C): body black- ish, with contrasting light yellow to yellow, broad to narrow bands at posterior edges of each of terga 2-11; axial stripe yellow, short, starting from behind caudal edge, not reaching 1/5-1/6 length of each tergite (Fig. 2A); in lateral view, terga 2-11 each with a large, reddish or carmine to red orange band each side, ~ 1/4-2/3 height of each tergum (Fig. 2B). Thoracic shield with a very large, lateral, reddish to red orange band each side at lateral edges, ~ 2/3-3/4 height of tergum in lateral view (Fig. 2A—C); anal shield (= pygidium) with a red- dish to red-orange band at the lateral and posterior edges, ~ 2/3-3/4 height of tergum (Fig. 2B). Head, collum and antennae black to dark brown, only labrum and Tomésvary’s organ brownish (Fig. 2C), venter and legs brownish to pale yellowish (Fig. 2C). Labrum sparsely setose (Fig. 2C). Gnathochilarium with 2+2 palps subequal in length. Eyes blackish, with 8-11+1 ommatidia, cornea convex and trans- lucent. Antennomere 6 long, ~ 2.3-2.5x as long as its height, dorsal margin strongly curved (Figs 2C, 3A). Disk of antennomere 7 beset with 55-62 small sensory cones apically (3) (Figs 2C, 3A). Organ of Tomésvary typical, horse- shoe-shaped, suboval, elongate, ~ 1.5—1.6x as long as broad. Collum as usual, with two transverse striae. Thoracic shield with a small hyposchism field not projecting past rear tergal margin (Fig. 2B); 7-9 mostly ZooKeys 1215: 235-257 (2024), DOI: 10.3897/zookeys.1215.130919 242 Natdanai Likhitrakarn et al.: A new Rhopalomeris species from Myanmar Figure 2. Rhopalomeris carnifex (Pocock, 1889), 4 specimen from Kala Island A-C dorsal, lateral, and ventral views. Scale bars: 5mm. superficial striae, only lower two or three lying in front of schism, one or two level to schism, remaining 2-4 behind schism, 6 and 7 complete striae, cross- ing the dorsum. Terga 3 and 4 relatively broadly rounded laterally (Fig. 2B). Following terga in front of pygidium faintly concave medially at caudal edge and with three or four striae starting above lateral edge, sometimes first and second stria fading away towards midway. Pygidium slightly concave medially at caudal edge. 3 legs 17 (Fig. 3B) simple, rather strongly reduced, with a rather low to medi- um-sized, often rounded, coxal lobe and a 4-segmented telopodite. Tarsus with 4-10 strong median and 1-3 strong apical spines (Fig. 3B). 3 legs 18 (Fig. 3C) simple, slightly reduced, without any evident outgrowths; syncoxite membranous, with a small, broad, arch-shaped syncoxite notch and a 4-segmented telopodite. Tarsus with a small, but strong apical spine. Telopods (= 3 legs 19) (Fig. 3D—F) with a rather large and roundly pentag- onal syncoxite lobe, this being flanked by two short, spiniform, acuminate and setose syncoxite horns, the latter being evidently lower than syncox- ite lobe (Fig. 3F). Telopodite 4-segmented, with a spine apically. Prefemur (Fig. 3D, E) subtrapeziform, with a conspicuous, elongated, robust, tuberculi- form, distomesal prefemoral trichostele with a rounded tip, extending to about half or distal boundary of femur (Fig. 3D, E). Femur (Fig. 3D, E) subtrapeziform, with a stout, relatively short femoral trichostele in anterior view, extending apically to ~ 1/2-3/4 prefemoral trichostele, in posterior view with a round- ed, slightly narrowed, subtrapeziform femoral process, this being strongly curved anterolaterally and gently tapering into an acuminate and pointed tip (Fig. 3D). Tibia stout, gently tapering distad and curved apicobasad towards femoral process, with an evident, distolateral tibial process, this being strong- ly curved mesad (Fig. 3E). Tarsus the smallest, subcylindrical, moderately sigmoid, strongly curved, narrowly rounded apically, with a robust and small terminal seta (Fig. 3D). ZooKeys 1215: 235-257 (2024), DOI: 10.3897/zookeys.1215.130919 243 Natdanai Likhitrakarn et al.: A new Rhopalomeris species from Myanmar Figure 3. Rhopalomeris carnifex (Pocock, 1889), 3 specimen from Kala Island A antenna, anterior view B leg 17, anterior view C leg 18 anterior view D, E telopod, anterior and posterior views F tip of syncoxital lobes (without scaling). Scale bars: 0.5 mm. Abbreviations: cx coxa, cxl coxal lobe, fe femur, fp femoral process, ft femoral trichostele, pf prefemur, pft prefemoral trichostele of telopod, sh syncoxital horn of telopod, sI syncoxital lobe of telopod, sn syncoxite notch, sx syncoxite, ta tarsus, ti tibia, tp tibial process. Remarks. The taxonomic status of R. carnifex presents a challenge. Pocock (1889) originally described both Glomeris carnifex and G. carnifex var. pallida in the same paper. However, the original description of G. carnifex lacked details, focusing solely on body coloration and a vague collection locality (south Te- nasserim, Myanmar). Pocock (1890) subsequently provided more information regarding the precise sampling locations, viz. south Tenasserim and Malwoon (= Maliwan, Kawthoung, Tanintharyi, Myanmar; Likhitrakarn et al. 2017). In contrast, the description of G. carnifex var. pallida from Elphinstone Island contained far more detail. Pocock (1889) provided information on the number of specimens (male and female individuals), body characteristics, the 18" pair of legs and the telopod structure, all accompanied by clear illustrations. Notably, G. carnifex and G. carnifex var. pallida differ only slightly in coloration, showing a central, longitudinal, carmine line and large, lateral, carmine spots on each tergite. Subsequently, Silvestri (1917) provided a more detailed description, accompa- nied by comprehensive illustrations, while still treating R. carnifex and R. carnifex var. pallida as two different taxa. He also treated G. bicolor sensu Verhoeff (1906) as a synonym with R. carnifex var. pallida (Pocock, 1889). In a recent study, Golo- vatch et al. (2011) formally synonymized R. carnifex var. pallida with R. carnifex. ZooKeys 1215: 235-257 (2024), DOI: 10.3897/zookeys.1215.130919 244 Natdanai Likhitrakarn et al.: A new Rhopalomeris species from Myanmar However, our recently obtained specimens from Kala Island, Myanmar (Fig. 1, green square) closely resemble the original description of G. carnifex var. pallida from Elphinstone Island (Fig. 1, red square) both in color pattern (Fig. 2) and morphological characters, especially the structure of their legs and telopod (Fig. 3) as described by Pocock (1889). These two geographically dis- tant populations (ca 50 km apart) (Fig. 1) share these similarities, indicating that they probably belong to the same taxon. As R. carnifex var. pallida is now synonymized under R. carnifex (Golovatch et al. 2011), we currently identify these specimens from Kala Island, Myanmar as R. carnifex. Although there were previous reports of R. carnifex from several localities in southern Thailand, preliminary analyses of a number of R. carnifex specimens from this area reveal notable intraspecific variation in coloration, morpholo- gy, and molecular genetics, suggesting an occurrence of cryptic species (un- published data). Therefore, a comprehensive redescription of newly retrieved male specimens from Kala Island, Myanmar in this study, comparing them with the original description of G. carnifex var. pallida from the nearby Elphinstone Island, is essential before any taxonomic revisions of other Thai specimens can be proposed. Furthermore, the morphological redescription of R. carnifex above is thus based only on these Myanmarese specimens. Rhopalomeris monacha Silvestri, 1917 Rhopalomeris (s.s.) monacha Silvestri, 1917: 143 (D). Rhopalomeris monacha — Golovatch et al. 2011: 6 (M); Golovatch and Semenyuk 2016: 414 (M, K); Nguyen et al. 2019: 292 (M); 2021: 259 (M). Remarks. This species was described from Perak State, western Malaysia (Silvestri 1917). The species remains known only from a female holotype (Silvestri 1917). Endemic to Malaysia. Rhopalomeris tonkinensis Silvestri, 1917 Rhopalomeris (s.s.) tonkinensis Silvestri, 1917: 144 (D). Rhopalomeris tonkinensis — Attems 1936: 194 (L); Golovatch 1983: 180 (L); Enghoff et al. 2004: 31 (L); Golovatch et al. 2011: 6 (M); Golovatch and Se- menyuk 2016: 414 (M, K); Nguyen et al. 2019: 263 (L, M); 2021: 259 (M). Remarks. This species was described from Tonkin, Montes Mauson, 2,000-3,000 ft. a.s.l., Lang Son Province, northern Vietnam (Silvestri 1917). The species is like- wise known only from a female holotype (Silvestri 1917). Endemic to Vietnam. Rhopalomeris variegata Golovatch & Semenyuk, 2016 Rhopalomeris variegata Golovatch & Semenyuk, 2016: 411 (D, kK). Rhopalomeris variegata — Golovatch 2017: 199 (D, R); Nguyen et al. 2019: 263 (L, M); 2021: 259 (M). ZooKeys 1215: 235-257 (2024), DOI: 10.3897/zookeys.1215.130919 245 Natdanai Likhitrakarn et al.: Anew Rhopalomeris species from Myanmar Remarks. This species was described from Vietnam, Gia Lai Province, Kon Chu Rang Nature Reserve, 14°30'54"N, 108°32'47'E, ca 1,000 ma.s.I. (Golovatch and Semenyuk 2016) and later reported from Kon Tum Province, Kon Plong District, Bak Khe River, 14°43.450'N, 108°18.882'E, ca 1,000-1,260 m a.s.I. (Golovatch 2017). Endemic to Vietnam. Rhopalomeris sauda Nguyen, Sierwald & Marek, 2019 Rhopalomeris sauda Nguyen et al., 2019: 292 (D, kK). Rhopalomeris sauda — Nguyen et al. 2021: 259 (R, M, MI). Remarks. This species was described from Vietnam, Bac Kan Province, Ba Be National Park, 400-500 m a.s.|.; Vinh Phuc Province, Phuc Yen Town, Ngoc Thanh Commune, Me Linh Station for Biodiversity, 21.385°N, 105.7119°E; Tam Dao district, Tam Dao National Park, 21.460945°N, 105.647021°E (Nguyen et al. 2019); Tuyen Quang province, Cham Chu Nature Reserve; Ha Giang Province, Khau Ca Nature Reserve (Nguyen et al. 2021). Endemic to Vietnam. Rhopalomeris nagao Nguyen, Nguyen & Eguchi, 2021 Rhopalomeris nagao Nguyen et al., 2021: 259 (D, K, Ml). Remark. This species was described from Vietnam, Cao Bang Province, Pia Oac — Pia Den National Park, 22.5540°N, 105.8622°E, 850-1,600 maz.s.I. (Nguyen et al. 2021). Endemic to Vietnam. Rhopalomeris nigroflava Likhitrakarn, sp. nov. https://Zzoobank.org/6D8B6CCE-FED1-49C9-9E20-ADD3FD6AF618 Figs 4-6 Material examined. Holotype: Myanmar — Kayin State + 3; Linno Gu (Lateral small cave); 16°50'52.9"N, 097°36'37.7"E; 25 Nov. 2015; F. Bréhier leg.; MY15- 13/01-CUMZ-GLO093. Paratypes: Myanmar - Kayin State > 7 6d 5 99; same locality as holotype; MY15-13/01-CUMZ-GLO093) : 2 34 2 99; same locality as holotype; MNHN-MY15-13/01. Diagnosis. Differs from other species of Rhopalomeris by the yellowish body with contrasting brown to blackish markings on terga 4-9 (Fig. 4A-F). Addi- tionally, characterized by the smallest body sizes (5.1—9.7 mm in length and 2.6-4.7 mm in width), coupled with the telopod syncoxital lobe being slightly lower than lateral syncoxite horns. For further details, see key below. Description. Body length of unrolled holotype,7.3 mm, width 4.1 mm. Body length of unrolled paratypes, 5.6-9.3 mm (0), 5.1-9.7 mm (9), width 3.1-4.8 (3), 2.6-4.7 mm (9). Color faded after nine years of preservation in alcohol (Fig. 4A—F): body yel- lowish to brown yellowish, with contrasting brown to blackish markings on ter- ga 4—9 (Fig. 4A, B, D, E); lateral sides of terga 10, 11, and anal shield sometimes ZooKeys 1215: 235-257 (2024), DOI: 10.3897/zookeys.1215.130919 246 Natdanai Likhitrakarn et al.: A new Rhopalomeris species from Myanmar Figure 4. Rhopalomeris nigroflava sp. nov., A-C 3 holotype in A dorsal B lateral and C ventral views D-F < paratypes D, E dorsal and F ventral views. Scale bars: 0.2 mm. with a pair of small, faint, dark paramedian spots, these reaching neither caudal nor lateral edges (Fig. 4A, B, D, E); head, antennae and collum brown to dark brownish, only labrum, vertex and TOmdsvary's organ light brown; venter yellow brown to light yellowish; legs pale brown to brownish, with basal part of each podomere whitish (Fig. 4C, F). Labrum sparsely setose (Figs 4C, F, 5A). Gnathochilarium with 2+2 palps subequal in length. Eyes blackish, with 6(7)+1 (4) ommatidia (Fig. 5A), 6-(9)+1 ommatidia (9), cornea convex and translucent. Antennomere 6 rather short, ~ 1.7-1.8x as long as its height, dorsal margin only slightly curved (Figs 4C, 5A, C). Disk of antennomere 7 beset with 22-28 small sensory cones apically (Fig. 5A, C), 16-26 small sensory cones apically (9). Toémésvary’s organ typical, horse- shoe-shaped, oblong-oval, elongate, ~ 1.6-1.7x as long as broad (Fig. 5A, C). Collum as usual, with two transverse striae (Fig. 5A). Thoracic shield with a small hyposchism field not projecting past rear tergal margin (Fig. 5B). ZooKeys 1215: 235-257 (2024), DOI: 10.3897/zookeys.1215.130919 247 Natdanai Likhitrakarn et al.: A new Rhopalomeris species from Myanmar A aay ee re 8 ~ ean INZ ’ » Figure 5. Rhopalomeris nigroflava sp. nov., 3 holotype A head and anterior part of body, ventral view B thoracic shield, lateral view C left antenna, frontal view D leg 18, anterior view. Scale bars: 1 mm (A, B), 0.2 mm (C), 0.4 mm (D). Abbrevi- ations: cxl coxal lobe, e eggs, hy hyposchism field, K caudomedial tubercle, sc schism, sn syncoxite notch, sx syncoxite. 7-9 mostly superficial striae, only lower 4 or 5 lying above schism, one level to schism, remaining 3 or 4 below schism, 6 or 7 complete, crossing the dorsum (Fig. 5B). Terga 3-7 rather broadly rounded laterally, with two or three striae starting above lateral edge, sometimes middle stria fading away mid-dorsally (Fig. 5B). Following terga in front of pygidium concave medially at caudal edge and with one or two striae starting above lateral edge. Male pygidium faintly concave medially at caudal edge (Fig. 4A, D, E). 3 legs 17 (Fig. 6A—-C) particularly strongly reduced, with a rather small to me- dium-sized, often irregularly rounded coxal lobe and a 4-segmented telopodite. Tarsus with 2-4 strong apical spines. 3 legs 18 (Fig. 5D) rather strongly reduced, with a rounded ogival syncoxital notch and a 4-segmented telopodite. Femur with a small, setose, caudomedial tubercle near apex. Tarsus with a small apical spine. ZooKeys 1215: 235-257 (2024), DOI: 10.3897/zookeys.1215.130919 248 Natdanai Likhitrakarn et al.: Anew Rhopalomeris species from Myanmar Figure 6. Rhopalomeris nigroflava sp. nov., A, B ¢ paratypes C-F 3 holotype A-C leg 17, anterior view D, E telopod, pos- terior and anterior views, respectively F, G tip of syncoxital lobes (without scaling). Scale bars: 0.2 mm. Abbreviations: cx coxa, cxl coxal lobe, fe femur, fp femoral process, ft femoral trichostele, pf prefemur, pft prefemoral trichostele of telopod, sh syncoxital horn of telopod, sl syncoxital lobe of telopod, ta tarsus, ti tibia, tp tibial process. Telopods (= 3 legs 19) (Fig. 6D—G) with a small subtrapeziform, narrowly and roundly emarginated syncoxital lobe, this being flanked by two setose syncox- ite horns, each of the latter higher than syncoxital lobe (Fig. 6D, E) and crowned by a subapical setoid filament (Fig. 6F, G). Telopodite 4-segmented. Prefemur (Fig. 6E) rectangular, with a conspicuous, elongated, robust, tuberculiform, di- stomesal prefemoral trichostele; in anterior view, with a rounded tip, extending to about half or distal boundary of femur (Fig. 6E). Femur (Fig. 6D, E) rectangu- lar, with a prominent, stout, relatively short femoral trichostele in anterior view, extending apically to ~ 1/2-3/4 prefemoral trichostele, in posterior view with a rounded, subtriangular femoral process, this being curved anterolaterally and gently tapering into an acuminate rounded tip distally (Fig. 6D, E). Tibia stout, gently tapering distally and curved apicobasally towards femoral process, with a rather large, distolateral tibial process strongly curved mesad (Fig. 6D, E), with a strong anterior seta in anterior view (Fig. 6D) near base of tibial process. Tar- sus the smallest, subcylindrical, moderately sigmoid, strongly curved, narrowly rounded apically, with a robust and small terminal seta (Fig. 6D, E). ZooKeys 1215: 235-257 (2024), DOI: 10.3897/zookeys.1215.130919 249 Natdanai Likhitrakarn et al.: Anew Rhopalomeris species from Myanmar Remarks. It seems noteworthy that a female and two male (Fig. 5C) speci- mens were found guarding a clutch of eggs near its head, beneath the thorac- ic shield. This behavior deviates from the typical reproductive strategy so far known in the entire order Glomerida, where females deposit eggs in specialized clay chambers and leave them to develop independently (Thomas et al. 1970; Janssen 2013). This is the first instance of paternal brood care observed in Glomerida. Therefore, this newly discovered species presents fascinating traits worthy of a dedicated future study. Etymology. The specific epithet nigroflava is derived from the Latin niger meaning black and flavus meaning yellow, in reference to the dark bands on a yellowish dorsum, adjective in feminine gender. Key to known species of Rhopalomeris, based on adults, modified from Golovatch (2017) 1 Thoracic shield yellowish or yellowish brown, contrasting to dark body DACK COUN CS tte Breas vn Aeterna Maa cn bare aes uate feats oe enna eee aM katate 2 = ~~ thoracic shield .darke variegated... ......<.2.cncsecetnenrsdsacevieteecdenscseaebeediaacendess 3 2 Body larger, ~ 12 mm in length and 6 mm in width. Head, collum and tho- racic shield light yellowish, body mostly blackish with a light, rather broad, axial stripe. Perak State, western MalaySsia..............c::cccsseeee R. monacha - Body the smallest, 5.1-9.7 mm in length and 2.6-4.7 mm in width. Body yellowish to yellowish brown-, contrasting to brown to blackish terga 4-9 (Fig. 4A, B, D, E). Head and collum brown to dark brownish (Fig. 5C, E, F). Kayin; State;, My Anima svc cccse. nce cedecttareh ant cave eva tetvans v< R. nigroflava sp. nov. 3 Body large-sized, ~ 20 mm in length and 11 mm in width (Q). Dorsum: mostly blackish, not variegated. Mount Mau Son, Lang Son Province, laleladgicitats’s(ch: ays 11 9 hae a eeeeeees pee ee eee. eo. OO 1 cee ee R. tonkinensis - Body < 20 mm in length and 11 mm in width. Dorsum: with a varied color DAMeN GF -CONMASUNG COLOFS Lc. cw rea cecctutrncte iw a ezsadihe necave rea cadetumrnsctn sanced 4 4 Dorsum mostly dark, lateral edges of terga contrasting reddish or car- mine. Telopod syncoxital lobe clearly higher than lateral syncoxite horns (Fig. 3D), each latter with a tiny filament on top (Fig. 3D, F). Southern Thai- land and southern Myanmar (Fig. 1) .........:ccccccccscesseseeseeseeseeseens R. carnifex* - Dorsum dark or light, sometimes variegated, lateral edges of terga neither reddish nor carmine. Telopod syncoxital lobe clearly shorter than lateral syncoxite horns, each latter without filament on top. Vietnam................... 5 5 Body almost entirely dark with contrasting four yellow lateral spots on each of terga 3-11. Telopods with a medially slightly concave syncoxite lobe. Prefemoral trichostele short, not extending to about half the distal boundary of femur. Femoral process (fp) long, narrow, erect, acute at tip. Tibial process. short:and lODUNNPOPM 1.2 os. cocccdeveen tec coer tatieareceae ee R. nagao - Body color variegated. Telopods with a medially slightly convex syncoxite lobe. Prefemoral trichostele long, extending to about half or distal bound- ary of femur. Femoral process large, subtrapeziform, rounded at tip. Tibial process long:and SIQMOIdAMeSally =. : kant escctek ethane a ceshineeccndedt seed 6 * The current key does not take the variation of R. carnifex from southern Thailand into consideration, see Remarks under R. carnifex above. ZooKeys 1215: 235-257 (2024), DOI: 10.3897/zookeys.1215.130919 250 Natdanai Likhitrakarn et al.: Anew Rhopalomeris species from Myanmar Body light brown to blackish, with variegated, marbled, brown-yellow to yellowish markings. Body larger, 15-18 mm in length and 7-8 mm in width. Antennomere 6 slightly shorter, ~ 2.0x as long as high. Thoracic shield with 8-10 striae. Central Vietnam. ...............cccceeeseeees R. variegata Body blackish, with contrasting yellowish, lateral, oval bands on each of terga 2-11. Body smaller, 11 mm in length and 6 mm in width. Antenno- mere 6 longer, 2.5-3x as long as high. Thoracic shield with 2-3 striae. NOK: MISTISIN .. 14 Save. Wie cei, co cce cadences bun vacpigeet eevee as R. sauda Phylogenetic analysis The COI alignment (Table 1) was 660 bp in length and contained 61 individuals, including 29 taxa from the Glomeridae as ingroup and two taxa from the Zeph- roniidae as outgroup. The tree shows that all 29 pill millipede species from the eight rated genera of Glomeridae form a monophyletic group that is evidently sepa- from the outgroup, with strong support values (100% BS for ML and 1 bpp for BI) (Fig. 7). However, most of the relationships at the generic level among glomerid species still remained unresolved. | Rhopalomeris 0.61 50 0.1 100 2 = Tonkinomeris napoensis 95 0.99 Hyleoglomeris tongkerdae 98 Hyleoglomeris bomba Hyleoglomeris halang Trachysphaera schmidtii 0.59 Trachysphaera lobata 68 Eupeyerimhoffia archimedis Trachysphaera costata 1 a F et 700 Glomeris marginata 47 1 _, GLOO16-1 | R 099 700 GLO016-2 a tol GLovgs2 | Rhopalome 0.98 79 0.99 100 0.99 99 Hyperglomeris simplex ae Hyleoglomeris lobus 0.99 0.88 100 69 Hyperglomeris bicaudata 0.98 1 . Ks 70 @ ~Peplomeris magna on Hyperglomeris inkhavilayi Hyleoglomeris uenoi a Hyleoglomeris dracosphaera 0.52 74 0.93 98 aaa Hyleoglomeris nigromaculata 0.91 74 0.82 a Hyleoglomeris hongkhraiensis Hyleoglomeris krasoon ‘ Hyleoglomeris suwannakhuhensis ¢- Hyleoglomeris lucida Hyleoglomeris insularum Hyleoglomeris sulcata oe 4 Hyleoglomeris awaumi 0.91 1 100 Figure 7. Bayesian inference tree (Bl) of Rhopalomeris species in this study a Hyleoglomeris japonica Zephronia laotica Sphaerobelum truncatum of pill millipedes in the family Glomeridae based on 660 bp of COI gene. Clades are highlighted in green. Numbers above branches indicate bipartition posterior probability (bpp) from Bayesian inference analysis (Bl) and numbers below branches are Bootstrap Support (BS) values from the ML analysis. ZooKeys 1215: 235-257 (2024), DOI: 10.3897/zookeys.1215.130919 251 Natdanai Likhitrakarn et al.: Anew Rhopalomeris species from Myanmar The COI tree revealed a sister relationship between R. carnifex and R. nigro- flava sp. nov., forming a well-supported clade 98% BS for ML and 0.99 bpp for Bl. However, all Rhopalomeris species, including R. sauda and R. nagao, were not retrieved together as monophyletic (Fig. 7). The interspecific divergences based on COI uncorrected p-distance among the glomerid species in this study ranged from 9.74 to 19.87%, with an average of 14.87% (data not show). The interspecific divergences among Rhopalomeris species ranged from 10.85 to 16.13%, with an average of 13.32% (Table 2). This analysis also demonstrates that the intraspecific divergence for Rhopalomeris nigroflava sp. nov. is 0%, vs 1.75% for R. carnifex. Table 2. Matrix of the average interspecific genetic divergence (uncorrected p-distance) for the 660 bp barcoding region of the COI gene between Rhopalomeris species. Taxa Rhopalomeris sauda | Rhopalomeris nagao | Rhopalomeris carnifex | Rhopalomeris nigroflava sp. nov. Rhopalomeris sauda 0.0744 Rhopalomeris nagao 0.1289 0.0521 Rhopalomeris carnifex 0.1613 0.1397 0.0175 Rhopalomeris nigroflava sp. nov. 0.1376 Ux235 0.1085 0 Discussion and conclusions Currently, the genus Rhopalomeris comprises seven species distributed across Viet- nam (four species), Myanmar (two species), Thailand and Malaysia (one species each), with a notable absence of documented sympatry of species. The distribu- tion patterns (Fig. 1), particularly the higher species diversity in Vietnam compared to the neighboring countries, suggest still a high probability of discovering new Rhopalomeris species in Cambodia and southern Thailand through future surveys. Rhopalomeris species occur at elevations ranging between 5 and 1,600 meters above sea-level. Apparently, most are narrow endemics restricted to their type lo- calities and are only rare to be encountered. The exceptions are R. sauda which boasts a wider distribution of roughly 180 kilometers, and R. carnifex that demon- strates a remarkably extensive range exceeding 1,200 kilometers and stretching from southern Myanmar through Thailand to northern Malaysia (Fig. 1). It seems noteworthy that our preliminary surveys of millipede diversity in southern Thailand have yielded a high level of variation in the shape and col- oration of R. carnifex, and high genetic diversity, suggesting a high-level intra- specific variation or the occurrence of cryptic species (unpublished data). This observation underscores the need for further research to comprehensively un- derstand the extent of this variation, ultimately paving the way for future stud- ies to definitively identify the R. carnifex complex. The interspecific divergence based on COI uncorrected p-distance among the Rhopalomeris species in this study ranged between 10.85-16.13%, aligning with previous findings for European Glomeris species (11.5-17.1%; Wesener 2015), Vietnamese glomeridan genera (13-15.8%; Nguyen et al. 2021), Hyper- glomeris species (8.81-12.48%, Likhitrakarn et al. 2023a), and Hyleoglomeris species (9.12-16.92%; Likhitrakarn et al. 2024). This consistency suggests that COI proves effective in identifying species-lev- el differentiation within Glomeridae. Even such species as R. carnifex and ZooKeys 1215: 235-257 (2024), DOI: 10.3897/zookeys.1215.130919 252 Natdanai Likhitrakarn et al.: Anew Rhopalomeris species from Myanmar R. nigroflava sp. nov. that are very closely related and form a well-supported clade show a significant p-distance of 10.85%. This indicates that there can be consid- erable variability in the COl gene even among closely related glomerid species. This study investigates the intraspecific COI divergence within Glomeridae millipedes. The low genetic intraspecific differences observed in Rhopalomeris carnifex (1.75%) and the newly described R. nigroflava sp. nov. (0%) are con- sistent with previous reports on Peplomeris magna (0.2%; Nguyen et al. 2021), some Hyleoglomeris (0-1.19%; Likhitrakarn et al. 2024) and Hyperglomeris species (0.45—5.30%; Likhitrakarn et al. 2023a). Analyzing the COI gene sequence is highly valuable in determining species boundaries and enabling precise classifications of glomerid species. Unsur- prisingly, most recent taxonomic studies on millipedes frequently employ this technique to distinguish between taxa. Unfortunately, the phylogenetic relation- ships in this study appear insufficient to resolve genus-level relationships within the family, as shown in this study and others (Nguyen et al. 2019, 2021; Liu and Golovatch 2020; Likhitrakarn et al. 2023a, 2024). Subsequent research should include other genetic markers, such as 16S and 28S ribosomal RNA genes, as well as more advanced techniques, such as transcriptomic and phylogenomic data in clarifying phylogenetic relationships (Means et al. 2021; Benavides et al. 2023; Likhitrakarn et al. 2023a). Nevertheless, it is necessary to conduct these investigations combined with analyzing morphological, distributional, and eco- logical characteristics in order to obtain a more integrative comprehension of the evolutionary relationships among glomerid species, particularly regarding the intraspecific variation observed in the R. carnifex complex. Acknowledgements We thank the members of the Animal Systematics Research Unit for their in- valuable assistance in the field. We owe an obligation of gratitude to Henrik Enghoff, Duc-Anh Nguyen, and Thomas Wesener, the reviewers, whose con- structive comments, grammatic corrections, and assistance have significantly improved the paper. Additional information Conflict of interest The authors have declared that no competing interests exist. Ethical statement No ethical statement was reported. Funding This study was funded by the Thailand Science Research and Innovation Fund of Chulalongkorn University (grant number DIS66230007) and the TRF (Thailand Research Fund) Senior Research Scholar. Author contributions NL, RS, PJ, PS, EJ, SP and CS collected and prepared specimens in the field. SP and CS provided financial and intellectual support. NL, RS, and EJ prepared specimens and ZooKeys 1215: 235-257 (2024), DOI: 10.3897/zookeys.1215.130919 253 Natdanai Likhitrakarn et al.: A new Rhopalomeris species from Myanmar wrote the manuscript. NL, RS, PJ, EJ, and CS conceived, designed, supervised the study, prepared figures, and approved and edited the final manuscript. SIG and SP reviewed, advised, and approved the final manuscript. Author ORCIDs Natdanai Likhitrakarn © https://orcid.org/0000-0002-1306-317X Sergei |. Golovatch © https://orcid.org/0000-0001-7159-5484 Ruttapon Srisonchai © https://orcid.org/0000-0002-7142-0999 Parin Jirapatrasilp © https://orcid.org/0000-0002-5591-6724 Pichsinee Sapparojpattana © https://orcid.org/0009-0005-9134-4910 Ekgachai Jeratthitikul © https://orcid.org/0000-0002-3477-9548 Somsak Panha ® https://orcid.org/0000-0002-4431-2458 Chirasak Sutcharit © https://orcid.org/0000-0001-7670-9540 Data availability All of the data that support the findings of this study are available in the main text. References Attems C (1914) Die indo-australischen Myriopoden. Archiv fiir Naturgeschichte 80A, 1398) Attems C (1936) Diplopoda of India. Memoirs of the Indian Museum 11(4): 133-323. 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