Research Article |
Corresponding author: Piyatida Pimvichai ( piyatida_pimvichai@yahoo.com ) Academic editor: Pavel Stoev
© 2023 Ruttapon Srisonchai, Natdanai Likhitrakarn, Chirasak Sutcharit, Thierry Backeljau, Piyatida Pimvichai.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Srisonchai R, Likhitrakarn N, Sutcharit C, Backeljau T, Pimvichai P (2023) A new jewel-like species of the pill-millipede genus Sphaerobelum Verhoeff, 1924 (Diplopoda, Sphaerotheriida, Zephroniidae) from Thailand. ZooKeys 1181: 41-57. https://doi.org/10.3897/zookeys.1181.109076
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A new species of the giant pill millipede genus Sphaerobelum is described: Sphaerobelum turcosa sp. 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. Sphaerobelum turcosa sp. nov. is restricted to limestone habitat in Loei province and is probably endemic for the Thai fauna.
Biodiversity, limestone karst, soil fauna, Southeast Asia, taxonomy
Limestone karsts in Southeast Asia are referred to as ‘arks of biodiversity’ and as such are a priority for biodiversity conservation (
The recent checklist of the millipedes (Diplopoda) of Thailand revealed 263 species. Of these, 222 species (84%) occur only in Thailand and are thus supposed to be endemic (
Recent fieldwork conducted in the impressive geological landscape at Phu Pha Lom Forest Park, Loei Province in the northeastern part of Thailand, has unveiled remarkable greenish-blue specimens of a giant pill-millipede which clearly belongs to the family Zephroniidae in the order Sphaerotheriida. Recently, the species diversity of this family in Thailand has gained considerable attention (
The external characteristics place the specimens within the genus Sphaerobelum and the present contribution aims at providing the formal description of this new Sphaerobelum species based on morphological and DNA data.
Specimens were hand-collected from limestone habitats in Phu Pha Lom Forest Park, Loei Province, Thailand, by visual spotting on open surfaces in daylight. Photographs of live animals were taken with a Canon 70D digital camera with a Canon EF-S 60 mm f/2.8 Macro USM lens. The specimens were euthanized based on AVMA guidelines for the euthanasia of animals (
The collecting sites were located by GPS using a Garmin GPSMAP 60 CSx, and all coordinates and elevations were rechecked with Google Earth. The background of the distribution map was downloaded from Elastic Terrain Map (http://elasticterrain.xyz/) (
This research was conducted under the approval of the Animal Care and Use Committee (Protocol Reviews No. IACUC-KKU-136/64 from Khon Kaen University) and No. 1723018 from Chulalongkorn University.
The specimens were examined and measured under a Nikon SMZ 745T trinocular stereo microscope, equipped with a Canon EOS 5DS R digital SLR camera. For scanning electron microscopy (SEM), the specimens were photographed with a JEOL, JSM-5410 LV microscope using gold-coated samples. Line drawings were based on photographs taken under the stereo microscope equipped with a digital SLR camera. All final images were processed and edited with Adobe Photoshop CS6.
The terminology of morphological descriptions follows
The holotypes, as well as most of the paratypes are housed in the Museum of Zoology, Chulalongkorn University (
The following abbreviations are used in the figures: Cx = coxa, cp = cuticular impression, ia = inner area, ma = middle area, o = operculum of vulva, oa = outer area, pm = posterior margin, Pre = prefemur, St-Pl = stigmatic plate, Syn-Cx = syncoxite.
Total genomic DNA was extracted from legs using the NucleoSpin Tissue kit following the manufacturer’s instructions. PCR amplifications and sequencing of the standard mitochondrial COI DNA barcoding fragment (
Specimens from which the COI gene fragment was analysed.
Species | Voucher code | COI accession numbers | Locality | References |
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Order Sphaerotheriida | ||||
Family Zephroniidae Gray, 1843 | ||||
Genus Sphaerobelum Verhoeff, 1924 | ||||
S. aesculus | NHMD 621694 | MW898738 | Thailand, Nakhon Si Thammarat Province, Khao Luang NP |
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S. benquii | SCAU MMY01 | OP339792 | China, Guizhou, Tongren City, Jiangkou County, Guanhe Town, Guanhe Village, Maomaoyan | Zhao et al. 2022 |
S. bolavensis | MHNG LT-10/24 | MK330982 | Laos, Champasak Province, Bolaven Plateau, 3 km S of Ban Nong Luang, Tad Kameud |
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S. denticulatum | MHNG | MK330984 | Laos, Oudomxai Province, ca 3 km E of Tad Lak 11, SE of Oudomxai city |
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S. huzhengkuni | SCAU SP03 | MT657328 | China, Guizhou Province, Tongren City, Fanjingshan National Nature Reserve |
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S. lachneeis | MHNG | MK330983 | Laos, Oudomxai Province, ca 3 km E of Tad Lak 11, SE of Oudomxai city |
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S. laoticum | SMF | MK330975 | Laos, Vientiane Province, Vang Vieng |
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S. meridionalis | MHNG 4B-2 | OM509648 | Thailand, Yala Province, Bannang Sata District, Bang Lang National Park, near Than To Waterfall |
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S. nigrum | SMF | MK330976 | Laos, Champasak Province, Muang Bachieng, Ban Lak 35, Tad Etu |
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S. peterjaegeri | SMF SD553 | MK330972 | Laos, Luang Prabang Province, SE Luang Prabang, Nam Khan, Ban Pak Bak, Houay Kho |
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S. phouloei | ZMUC00040257 | MK330974 | Laos, Houaphan Province, Phou Loei |
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S. schwendingeri | MHNG LT 10/03 | MK330978 | Laos, Vientiane Province, trail to Tham Pou Kham, W. of Vang Vieng |
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Sphaerobelum sp. L07 | ZMUC00040261 | MK330979 | Laos, Khammouane Province, Ban Khounkham [Khun Kham] (Nahin) |
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Sphaerobelum sp. L10 | SMF | MK330980 | Laos, Vientiane Province, Vang Vieng, W. of Nam Song, Tham Nam Or Khem |
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S. spinatum | ZMUC00040258 | MK330973 | Laos, Vientiane Province, Phou Khao Khouay |
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S. truncatum | FMNH-INS 0000 072 674 | JN885184 | Thailand, Nan Province, Song Khwae District, Na Rai Luang Subdistrict, Pang Hi Village |
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S. tujiaphilum | SCAU SD02 | OP339783 | China, Guizhou, Tongren City, Jiangkou County, Guanhe Town, Sidu Village | Zhao et al. 2022 |
S. turcosa sp. nov. SPPL1 |
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OR530087 | Thailand, Loei Province, Mueang Loei District, Phu Pha Lom Forest Park | This study |
S. turcosa sp. nov. SPPL2 |
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OR530088 | Thailand, Loei Province, Mueang Loei District, Phu Pha Lom Forest Park | This study |
Genus Zephronia Gray, 1832 | ||||
Z. dawydoffi | ZFMK Myr4504 | MK330971 | N/A |
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Z. lannaensis | ZFMK MYR4911 | OM509631 | Thailand, Chiang Mai Province, Mae Rim District, Mae Sa Valley |
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Z. laotica | ZFMK Myr3502 | MK330977 | Laos, Champasak Province, east of Mekong, Garden of Erawan Riverside Hotel |
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Z. ovalis | ZFMK Myr 0832 | JX486068 | Vietnam, Dong Nai Province, Cat Tien National Park |
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Z. panhai | ZFMK MYR8116 | OM509645 | Thailand, Ratchaburi Province, Ratchaburi and Photharam District, 18–20 km WNW of Ratchaburi |
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Z. phrain | MYR3500 | OM509635 | Thailand, Chiang Mai Province, Chiang Mai District, Doi Suthep, behind tourist market |
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Zephronia siamensis |
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OR530089 | Thailand, Chonburi Province, Sichang District, Koh Sichang | This study |
Zephronia sp. | NHMDK K45 | MW898741 | Thailand, Prachuap Khiri Khan Province, Mueang district, Aow Noi Temple |
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Zephronia sp. 1 | ZFMK MYR8787 | MW898740 | Thailand, Nakhon Si Thammarat Province, Sichon District, Khao Lark Waterfall |
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Zephronia sp. 2 | NHMD K56x9 | OM509650 | Thailand, Kanchanaburi Province, Si Sawat District, 50 km W of Kanchanaburi, Erawan Waterfall |
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Order Glomerida | ||||
Family Glomeridae Leach, 1815 | ||||
Genus Glomeris Latreille, 1802 | ||||
G. marginata | ZFMK18996 | MG931021 | Luxemburg, Schengen |
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Genus Hyleoglomeris Verhoeff, 1910 | ||||
H. japonica | MS20210617-02 | LC713423 | Japan, Kanagawa Prefecture, Fujisawa-shi, Enoshima Island |
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The COI data included 31 specimens, representing 19 specimens of the genus Sphaerobelum and 10 specimens of the genus Zephronia (Table
CodonCode Aligner (ver. 4.0.4, CodonCode Corporation) was used to assemble the forward and reverse sequences and to check for errors and ambiguities. All sequences were checked with the Basic Local Alignment Search Tool (BLAST) provided by NCBI and compared with reference sequences in GenBank. Sequence alignment (660 bp) was done with MUSCLE (ver. 3.6, see http://www.drive5.com/ muscle;
The best-fit substitution model was implemented using JModelTest2 on XSDXE 2.1.6 (
Uncorrected p-distances between the sequences range from 0.00 to 0.32 (Table
Estimates of cytochrome c oxidase I (COI) sequence divergences (uncorrected p-distances) within and among Zephroniidae species and related taxa (rounded to two decimal places).
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | ||
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1 | Sphaerobelum benquii | |||||||||||||||||||||||||||||||
2 | Sphaerobelum bolavensis | 0.21 | ||||||||||||||||||||||||||||||
3 | Sphaerobelum denticulatum | 0.20 | 0.20 | |||||||||||||||||||||||||||||
4 | Sphaerobelum huzhengkuni | 0.18 | 0.22 | 0.18 | ||||||||||||||||||||||||||||
5 | Sphaerobelum lachneeis | 0.23 | 0.20 | 0.21 | 0.21 | |||||||||||||||||||||||||||
6 | Sphaerobelum laoticum | 0.19 | 0.21 | 0.18 | 0.16 | 0.21 | ||||||||||||||||||||||||||
7 | Sphaerobelum nigrum | 0.19 | 0.19 | 0.20 | 0.19 | 0.21 | 0.19 | |||||||||||||||||||||||||
8 | Sphaerobelum peterjaegeri | 0.19 | 0.16 | 0.19 | 0.18 | 0.21 | 0.19 | 0.19 | ||||||||||||||||||||||||
9 | Sphaerobelum phouloei | 0.20 | 0.18 | 0.17 | 0.17 | 0.21 | 0.18 | 0.19 | 0.18 | |||||||||||||||||||||||
10 | Sphaerobelum schwendingeri | 0.19 | 0.18 | 0.18 | 0.17 | 0.21 | 0.14 | 0.20 | 0.18 | 0.17 | ||||||||||||||||||||||
11 | Sphaerobelum sp. L07 | 0.21 | 0.21 | 0.22 | 0.20 | 0.24 | 0.21 | 0.21 | 0.19 | 0.20 | 0.20 | |||||||||||||||||||||
12 | Sphaerobelum sp. L10 | 0.19 | 0.19 | 0.20 | 0.21 | 0.22 | 0.16 | 0.17 | 0.18 | 0.18 | 0.16 | 0.19 | ||||||||||||||||||||
13 | Sphaerobelum aesculus | 0.20 | 0.20 | 0.21 | 0.19 | 0.24 | 0.21 | 0.22 | 0.19 | 0.21 | 0.20 | 0.22 | 0.20 | |||||||||||||||||||
14 | Sphaerobelum meridionalis | 0.19 | 0.20 | 0.20 | 0.18 | 0.22 | 0.18 | 0.20 | 0.18 | 0.17 | 0.18 | 0.21 | 0.19 | 0.17 | ||||||||||||||||||
15 | Sphaerobelum spinatum | 0.22 | 0.18 | 0.20 | 0.20 | 0.22 | 0.20 | 0.21 | 0.19 | 0.18 | 0.20 | 0.20 | 0.20 | 0.24 | 0.22 | |||||||||||||||||
16 | Sphaerobelum truncatum | 0.21 | 0.18 | 0.20 | 0.19 | 0.21 | 0.18 | 0.20 | 0.10 | 0.18 | 0.19 | 0.21 | 0.19 | 0.20 | 0.19 | 0.21 | ||||||||||||||||
17 | Sphaerobelum tujiaphilum | 0.20 | 0.21 | 0.18 | 0.12 | 0.21 | 0.18 | 0.20 | 0.19 | 0.17 | 0.17 | 0.21 | 0.21 | 0.21 | 0.17 | 0.19 | 0.20 | |||||||||||||||
18 | Sphaerobelum turcosa sp. nov. SPPL1 | 0.21 | 0.19 | 0.20 | 0.18 | 0.23 | 0.19 | 0.20 | 0.18 | 0.17 | 0.18 | 0.21 | 0.20 | 0.21 | 0.20 | 0.21 | 0.18 | 0.18 | ||||||||||||||
19 | Sphaerobelum turcosa sp. nov. SPPL2 | 0.20 | 0.19 | 0.20 | 0.18 | 0.23 | 0.18 | 0.20 | 0.18 | 0.17 | 0.18 | 0.21 | 0.19 | 0.21 | 0.20 | 0.21 | 0.18 | 0.18 | 0.00 | |||||||||||||
20 | Zephronia dawydoffi | 0.21 | 0.22 | 0.22 | 0.18 | 0.23 | 0.20 | 0.19 | 0.20 | 0.19 | 0.21 | 0.20 | 0.21 | 0.20 | 0.19 | 0.21 | 0.20 | 0.20 | 0.18 | 0.18 | ||||||||||||
21 | Zephronia lannaensis | 0.22 | 0.19 | 0.22 | 0.20 | 0.22 | 0.22 | 0.20 | 0.21 | 0.21 | 0.21 | 0.22 | 0.22 | 0.22 | 0.20 | 0.22 | 0.20 | 0.20 | 0.20 | 0.20 | 0.17 | |||||||||||
22 | Zephronia laotica | 0.25 | 0.23 | 0.22 | 0.20 | 0.24 | 0.22 | 0.19 | 0.21 | 0.21 | 0.23 | 0.23 | 0.24 | 0.21 | 0.20 | 0.23 | 0.22 | 0.21 | 0.20 | 0.20 | 0.16 | 0.18 | ||||||||||
23 | Zephronia ovalis | 0.22 | 0.21 | 0.24 | 0.21 | 0.23 | 0.23 | 0.20 | 0.20 | 0.22 | 0.23 | 0.25 | 0.22 | 0.23 | 0.23 | 0.22 | 0.21 | 0.22 | 0.20 | 0.20 | 0.15 | 0.20 | 0.16 | |||||||||
24 | Zephronia panhai | 0.20 | 0.20 | 0.23 | 0.21 | 0.23 | 0.21 | 0.20 | 0.21 | 0.22 | 0.21 | 0.23 | 0.22 | 0.22 | 0.21 | 0.21 | 0.21 | 0.19 | 0.19 | 0.19 | 0.18 | 0.15 | 0.20 | 0.19 | ||||||||
25 | Zephronia phrain | 0.22 | 0.21 | 0.24 | 0.19 | 0.24 | 0.20 | 0.17 | 0.20 | 0.20 | 0.20 | 0.22 | 0.21 | 0.21 | 0.21 | 0.22 | 0.21 | 0.20 | 0.19 | 0.19 | 0.19 | 0.22 | 0.19 | 0.20 | 0.21 | |||||||
26 | Zephronia siamensis | 0.21 | 0.21 | 0.21 | 0.19 | 0.24 | 0.22 | 0.19 | 0.19 | 0.19 | 0.23 | 0.21 | 0.21 | 0.19 | 0.19 | 0.21 | 0.20 | 0.20 | 0.19 | 0.19 | 0.10 | 0.19 | 0.14 | 0.15 | 0.19 | 0.19 | ||||||
27 | Zephronia sp. | 0.23 | 0.21 | 0.23 | 0.21 | 0.24 | 0.19 | 0.21 | 0.19 | 0.20 | 0.20 | 0.20 | 0.19 | 0.20 | 0.20 | 0.21 | 0.21 | 0.19 | 0.20 | 0.20 | 0.20 | 0.23 | 0.22 | 0.23 | 0.21 | 0.20 | 0.21 | |||||
28 | Zephronia sp. 1 | 0.23 | 0.20 | 0.24 | 0.21 | 0.24 | 0.23 | 0.20 | 0.20 | 0.21 | 0.22 | 0.22 | 0.22 | 0.20 | 0.21 | 0.22 | 0.21 | 0.21 | 0.21 | 0.21 | 0.22 | 0.22 | 0.21 | 0.22 | 0.20 | 0.21 | 0.21 | 0.17 | ||||
29 | Zephronia sp. 2 | 0.19 | 0.20 | 0.20 | 0.19 | 0.20 | 0.19 | 0.19 | 0.18 | 0.21 | 0.21 | 0.22 | 0.20 | 0.19 | 0.18 | 0.21 | 0.18 | 0.18 | 0.19 | 0.19 | 0.17 | 0.13 | 0.18 | 0.18 | 0.12 | 0.21 | 0.17 | 0.19 | 0.21 | |||
30 | Glomeris marginata | 0.29 | 0.29 | 0.29 | 0.27 | 0.33 | 0.28 | 0.29 | 0.28 | 0.27 | 0.30 | 0.29 | 0.29 | 0.28 | 0.30 | 0.28 | 0.29 | 0.28 | 0.29 | 0.29 | 0.30 | 0.30 | 0.31 | 0.30 | 0.30 | 0.29 | 0.29 | 0.27 | 0.29 | 0.29 | ||
31 | Hyleoglomeris japonica | 0.29 | 0.29 | 0.30 | 0.29 | 0.33 | 0.28 | 0.30 | 0.30 | 0.27 | 0.28 | 0.30 | 0.28 | 0.29 | 0.32 | 0.30 | 0.30 | 0.29 | 0.30 | 0.30 | 0.30 | 0.31 | 0.31 | 0.32 | 0.30 | 0.30 | 0.31 | 0.28 | 0.31 | 0.31 | 0.15 |
In the phylogenetic tree based on the COI gene (Fig.
The COI gene tree based on maximum likelihood analysis of cytochrome c oxidase I (COI) (660 bp). Numbers at nodes indicate branch support based on bootstrapping. Scale bar: 0.6 substitutions per site. # marks branches with <50% bootstrap support. The colored area marks Sphaerobelum turcosa sp. nov.
Family Zephroniidae Gray, 1843
Subfamily Zephroniinae Gray, 1843
Tribe Zephroniini Gray, 1843
Genus Sphaerobelum Verhoeff, 1924
Holotype
♂ (
Paratypes. 5 ♂, 2 ♀ (
The specific name is a Latin adjective, meaning ‘turquoise, greenish-blue mineral,’ and refers to the general body color of living specimens.
Coxal process on leg 2 sharply projecting, tarsi of legs 4–21 with 4/5/6/7/8 ventral spines. Similar in these respects to S. lachneeis, S. schwendingeri and S. laoticum, but S. turcosa sp. nov. differs from them by the combination of several characters, viz. body yellow contrasting to dominant greenish-blue color (vs. dark green/black); mesal margin of femur with teeth (vs. without teeth); vulva board and large, covering mesal 2/3 of coxa (vs. narrower, covering mesal 1/3 or half of coxa); anterior telopod consisting of 4 conspicuous telopoditomeres (vs. 3 telopoditomeres); immovable fingers of posterior telopod slender (vs. strongly humped and swollen).
Measurements : Male Holotype. Body length ca 18.5 mm. Width, of thoracic shield = 9.5 mm, of tergite 8 = 10.3 mm (= broadest). Height, of thoracic shield = 5.1 mm, of tergite 7 = 5.3 mm (= highest). Male: body length = 15.2–18.4 mm. Width, of thoracic shield = 7.9–9.0 mm, of tergite 8 = 8.7–9.4 mm. Height, of thoracic shield = 4.8–5.6 mm, of tergite 7, 5.2–6.2 mm. Female: body length = 20.6–24.5 mm. Width, of thoracic shield = 6.3–10.6 mm, of tergite 8 = 7.2–11.6 mm. Height, of thoracic shield = 5.4–6.0 mm, of tergite 7, 5.7–6.7 mm.
Coloration
: Live animals yellow with contrasting greenish-blue anterior margins of tergites and darker blue dorsal axial stripe (Fig.
Head : trapezoid, anterior part of the head with many long setae, posterior part densely dimpled; anterior margin of labrum with a single tooth. Eyes with 37–63 ocelli (male) or 55–67 (female). Aberrant ocellus located inside antennal groove.
Antennae
: short, with rounded joints, extending posteriorly to leg-pair 3. Lengths of antennomeres: 2<3=4<1<5<6. All antennomeres densely pubescent, sensilla basiconica surrounding apical disc. Last antennomere thickened, apically widened and well rounded (Fig.
Gnathochilarium : Structure typical of the Sphaerotheriida. Palpi with sensory cones arranged in clusters.
Mandibles : not dissected.
Collum : with glabrous surface, except for anterior and posterior margin with a few isolated and long setae.
Stigmatic plates
: first stigmatic plate rounded, apex well-rounded, slightly curved towards coxa (Fig.
Laterotergites : laterotergite 1 strongly projecting into a sharp tip. Laterotergite 2 with a broad, stout projection and a deep notch at lateral margin, like following laterotergites.
Following tergites : surface glabrous, shining, except the groove of paratergite with tiny setae. Tips of paratergites of midbody tergites projecting posteriorly.
Thoracic shield : surface glabrous as in tergites. Shallow grooves with few setae, surface glabrous, no keels.
Endotergum
: Posterior margin (pm) flat, regular (Fig.
Anal shield
: slightly sexually dimorphic, in female large and well-rounded (Fig.
Legs
: leg-pair 1 with 1 or 2 ventral spines, leg-pair 2 with 3 or 4, leg-pair 3 with 5 or 6. First two leg-pairs without an apical spine. Leg pairs 4–21 with 6 or 7 ventral spines and one apical spine. In leg 9, femur 1.6 times, tarsus 3.5 times longer than wide (Fig.
Female sexual characters
: vulva large, covering 2/3 of coxa, located at mesal margin, extending mesally to anterior third of prefemur (Fig.
Male sexual characters
: gonopore large, covered with a single, undivided, triangular, sclerotized plate (Fig.
Anterior telopods
(Fig.
Sphaerobelum turcosa sp. nov. ♂ paratype, SEM micrographs of the endoterga on the midbody segment. A all areas of endotergum, posterior margin (pm), outer area (oa), middle area (ma), cuticular impressions (cp) and inner area (ia) B middle area and cuticular impressions C bristles D inner area.
Posterior telopods
(Fig.
Currently known only from the type locality. All specimens were crawling openly on the bottom of several holes in humid rocks (Fig.
1 | Legs 4–21 usually with one apical spine. Posterior telopods: immovable finger of telopoditomere 2 without membranous spot | 2 |
– | Legs 4–21 usually with three apical spines. Posterior telopods: immovable finger of telopoditomere 2 with membranous spot, visible in posterior view | 3 |
2 | Greenish-blue body color. Male body length 15.2–18.4 mm. Endotergum with regular flat margin (Fig. |
S. turcosa sp. nov. |
– | Brown body color. Male body length 18.6–24.0 mm. Endotergum with ‘rectangle-wavy’ margin. Leg 3 with one apical spine. Coxa of second leg laterally without a sharp and long process. Posterior telopods: distal part of immovable finger of telopoditomere 2 strongly enlarged, tip not curved | S. truncatum Wongthamwanich, 2012 |
3 | Endotergum with two rows of bristles. First coxae with mesal process. Prefemur of midbody legs with mesal process. Telopoditomere 3 and 4 of anterior telopods clearly separated | S. meridionalis Bhansali & Wesener, 2022 |
– | Endotergum with one row of bristles. First coxae without mesal process. Prefemur of midbody legs without mesal process. Telopoditomere 3 and 4 of anterior telopods incompletely fused | S. aesculus Rosenmejer & Wesener, 2021 |
The new species can be distinguished from congeners by its greenish-blue color in combination with (1) a protruding coxal process, (2) a slender shape of the immovable finger, and (3) the shape of the posterior telopod. Yet, on the basis of morphology, little can be said about the relationships with other putatively closely related species. The overlapping COI p-distances and the phylogenetic tree were unable to resolve the relationships both within and among the genera Sphaerobelum and Zephronia. A similar unresolved tree was reported for the genus Sphaerobelum by
The new species exhibits a striking greenish-blue coloration, by which it joins other brightly colored millipedes such as the genus Apheloria (A. polychroma) and the genus Desmoxytes (D. purpurosea, D. rubra and D. aurata). Species of this latter genus are not only very colorful, but they also have long spine-like paraterga. These characteristics are probably aposematic (
The occurrence of the new species in Phu Pha Lom Forest Park is possibly correlated with the type of habitat/microhabitats. Due to its heterogenous topologies, its strongly irregular geomorphology and the good drainage of the limestone substrate, the type locality of S. turcosa sp. nov. probably provides suitable conditions to harbour a rich soil fauna.
With the discovery of S. turcosa sp. nov., the number of Sphaerobelum species in Thailand increases to four, which is still less than the number of Sphaerobelum species in Laos (10 species) and Vietnam (6 species) (
We thank our colleagues of the Animal Systematic Research Unit (ASRU), Chulalongkorn University, Mr. Sathit Saratan (Sirindhorn Museum) and the Department of National Parks, Wildlife and Plant Conservation of Thailand for assistance in collecting specimens. We are grateful to the editor and referees for their critical comments which helped to improve the manuscript.
The authors have declared that no competing interests exist.
The approval of the Animal Care and Use Committee (Protocol Reviews No. IACUC-KKU-136/64 from Khon Kaen University) and No. 1723018 from Chulalongkorn University.
This research was funded by the Fundamental Fund (Basic Research) of Khon Kaen University and the Research Grant for New Scholar (RGNS65-056).
Conceptualization: PP. Funding acquisition: RS. Investigation: RS, PP, NL. Resources: PP, CS. Supervision: PP. Writing – original draft: RS. Writing – review and editing: PP, TB, CS.
Ruttapon Srisonchai https://orcid.org/0000-0002-7142-0999
Natdanai Likhitrakarn https://orcid.org/0000-0002-1306-317X
Chirasak Sutcharit https://orcid.org/0000-0001-7670-9540
Thierry Backeljau https://orcid.org/0000-0002-9057-9727
Piyatida Pimvichai https://orcid.org/0000-0001-9765-821X
All of the data that support the findings of this study are available in the main text.