Research Article |
Corresponding author: Weixin Liu ( da2000wei@163.com ) Academic editor: Pavel Stoev
© 2020 Weixin Liu, Sergei Golovatch.
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:
Liu W, Golovatch S (2020) The first representatives of the millipede family Glomeridellidae (Diplopoda, Glomerida) recorded from China and Indochina. ZooKeys 954: 1-15. https://doi.org/10.3897/zookeys.954.54694
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A new species of glomeridellid millipede is described from Guizhou Province, southern China: Tonkinomeris huzhengkuni sp. nov. This new epigean species differs very clearly in many structural details, being sufficiently distinct morphologically and disjunct geographically from T. napoensis Nguyen, Sierwald & Marek, 2019, the type and sole species of Tonkinomeris Nguyen, Sierwald & Marek, 2019, which was described recently from northern Vietnam. The genus Tonkinomeris is formally relegated from Glomeridae and assigned to the family Glomeridellidae, which has hitherto been considered strictly Euro-Mediterranean in distribution and is thus new to the diplopod faunas of China and Indochina. Tonkinomeris is re-diagnosed and shown to have perhaps the basalmost position in the family Glomeridellidae. Its relationships are discussed, both morphological and zoogeographical, within and outside the Glomeridellidae, which can now be considered as relict and basically Oriental in origin. Because of the still highly limited array of DNA-barcoding sequences of the COI mitochondrial gene available in the GenBank, the first molecular phylogenetic analysis of Glomerida attempted here shows our phylogram to be too deficient to consider meaningful.
DNA barcode, evolution, Glomeridella, key, molecular phylogram, new diagnosis, new species, new transfer, Tonkinomeris, Typhloglomeris, Vietnam, zoogeography
The chiefly Holarctic millipede order Glomerida (
Continental China, unlike the Nearctic + Southeast Asia + Taiwan which contain several genera of Glomeridae (11) and Protoglomeridae (1) (
All the more interesting is the discovery of a new species of Tonkinomeris in southern China. Moreover, this genus appears to actually belong to the family Glomeridellidae, being formally transferred therein from Glomeridae where it was originally placed. This represents the first formal records of glomeridellids not only in China, but also in entire Asia east of Hyrcania (the Republic of Azerbaijan and northeastern Iran near the Caspian Sea coast). The present paper is devoted to a description of our new species and to a discussion of its morphological, molecular and zoogeographical affinities.
The underlying material was taken from leaf litter in a protected forest patch and preserved in 95% ethanol. The types are deposited in the Zoological Collection of the South China Agricultural University (
Genomic DNA was extracted from legs and thoracic tissue of the paratype with Qiagen DNeasy Blood and Tissue kit following the manufacturer’s extraction protocol. Fragments of the COI gene were amplified using the degenerate primer pair HCO2198-JJ (AWACTTCVGGRTGVCCAAARAATCA) / LCO1490-JJ (CHACWAAYCATAAAGATATYGG) (
The sequences were aligned using Clustal W and edited in Bioedit (
Considering the new species described below, the following amended diagnosis of Tonkinomeris can be proposed.
Order Glomerida Leach, 1814
Family Glomeridellidae Cook, 1896
Tonkinomeris napoensis Nguyen, Sierwald & Marek, 2019, from northern Vietnam, by original designation (
Other species included: T. huzhengkuni sp. nov., southern China.
A genus of Glomeridellidae with the caudal margins of several ♂ tergites sometimes modified into small lobes drawn posteriad into small lobes; the caudal margin of the ♂ pygidium is clearly emarginate centrally; the anterior telopods are flattened sagittally, somewhat incrassate, with evident mesal outgrowths on either T3 alone or both T2 and T3; posterior telopods with a trichotele (sometimes rudimentary) on T1, each of T2 and T3 with a caudal process and both forming a rather indistinct apical pincer.
Holotype: ♂ (
Honours Mr Huzhengkun, the collector and a millipede fan. A noun in genitive case.
Differs from T. napoensis Nguyen, Sierwald & Marek, 2019, the sole other species of the genus (
Body length of holotype ♂ ca 12.5 mm, width of thoracic shield ca 8.0 mm (broadest), height of thoracic shield ca 4.2 mm (highest). Body length of paratype ♀, 11.2 mm, width of thoracic shield ca 7.1 mm (broadest), height of thoracic shield ca 4.0 mm (highest). Coloration (Fig.
Head
: mandibles (Fig.
Collum
with two complete transverse striae (Fig.
Legs
long and slender. All podomeres densely setose, setae mostly being short. Coxae 1–16 each with a short, well-rounded, spinigerous, apico-mesal projection, this being especially evident in coxae 1 and 2 (Fig.
Male sexual characters
: gonopore small, oval, with a few short setae around (Fig.
Vulva
(Fig.
Tonkinomeris huzhengkuni sp. nov., ♀ paratype. A Gnathochilarium, ventral view, in situ B, C left mandible, mesal and subfrontal views, respectively D coxae 2 with vulvae. Abbreviations: ca: cardines of gnathochilarium, et: external tooth, gu: gula, iA: intermediate area, ip: inner palpus, it: inner tooth, ll: lamellae linguales, lp: lateral palpus, m: mentum, md: basal joint of mandible, mf: membranous fringe, mg: molar groove, mp: molar plate, pl: pectinate lamellae, st: stipites, vu: vulvae.
Tonkinomeris huzhengkuni sp. nov., ♂ holotype. A Left leg17, oral view B right anterior telopod, oral view C right anterior telopod, caudal view D–F left posterior telopod, oral, mesal and caudal views, respectively G tip of syncoxital horn, caudal view. Abbreviations: cx: coxa, st: sternite, sx: syncoxite, t1–t4: telopoditomeres 1–4. Scale bars: 0.5 mm (A–C, left); 0.5 mm (D–G, right).
Originally, Tonkinomeris was described in the family Glomeridae Leach, 1815, tentatively assigned to the subfamily Haploglomerinae Mauriès, 1971, and compared to the genus Peplomeris Silvestri, 1917, with two species from northern Vietnam (
In addition, like most species of Typhloglomeris, the caudal margins of a few ♂ tergites in front of the pygidium in Tonkinomeris huzhengkuni sp. nov. are modified, each drawn medially posteriad into a small, albeit glabrous, lobe (thus, clearly apomorphous), vs remaining simple and unmodified (plesiomorphous) in T. napoensis. In contrast, the particularly strongly reduced, 2- or 3-segmented ♂ telopodites 17 in T. napoensis definitely represent an apomorphous condition compared to the usual, 4-segmented ♂ telopodites 17 observed in T. huzhengkuni sp. nov. and most other Glomerida. The presence of a sharp caudomesal tooth also on T2 of the anterior telopod, vs its absence from T. napoensis, is difficult to polarize in terms or apo- or plesiomorphy. However, the particularly strongly developed central syncoxital lobe and the especially small syncoxital horns, as well as the rudimentary trichostele on T1 of the posterior telopods, all observed in T. huzhengkuni sp. nov. as opposed to their more usual states in T. napoensis, seem to be apomorphous. Therefore, each of the species combines both apo- and plesiomorphies in a number of traits. Most of the characters seem to be more advanced (apomorphous) in T. huzhengkuni sp. nov. compared to T. napoensis, but a few others vice versa (e.g., the more strongly reduced ♂ legs 17). What appears evident in any case is, that overall Tonkinomeris seems to represent the most primitive, perhaps even the basalmost genus of Glomeridellidae. This is primarily because both T. napoensis and T. huzhengkuni sp. nov. still show very modest modifications of the ♂ tergites and pygidium, while their posterior telopods feature a trichostele on T1 and yet underdeveloped apical pincers formed by T2 and T3.
Glomeridae, in contrast to Glomeridellidae, are distinct in the posterior telopods (♂ legs 19) typically being stouter, clearly curved mesad, by themselves forming a strong pincer, some telopoditomeres before last one showing a mesal trichostele or its vestige, while each telopodite is devoid of clear-cut apical pincers. The Protoglomeridae seems to be a polyphyletic group (
The phylogeny of Glomerida as recently recovered by
The molecular sequences available in the GenBank and used in our phylogenetic analysis, which is apparently the first to be attempted for the entire order Glomerida, have allowed for two phylograms to be obtained. Since both BI and ML trees are similar and neither is congruent with the morphology-based phylogeny recovered by
The following key to the accepted genera of Glomeridellidae can be offered:
1 | Penultimate (11th) tergite just in front of pygidium strongly reduced, visible only laterally as thin ribbons. Caudal margins both of tergites and pygidium regularly rounded caudally, unmodified. Tergites densely and finely pubescent. Anterior telopods strongly elongate, subcylindrical, T2 and T4 forming a pincer, T3 being small. Syncoxital lobe of 3-segmented posterior telopod telopodites very simple and low, a trichostele on T1 absent, both T2 and T3=4 forming a pincer (apparently, true T3 being totally reduced). Western Europe east to northwestern Balkans | Glomeridella |
– | No tergites reduced. Caudal margin of tergites and pygidium either unmodified and regularly rounded or (in ♂ only) modified. Tergites bare. Anterior telopods relatively stout, mostly flattened sagittally, each forming no apical pincer. Syncoxital lobe of posterior telopods higher and variously shaped, telopodites 3- (more rarely) or 4-segmented, usually elongate, slender, suberect and each forming a more or less distinct apical pincer | 2 |
2 | Caudal margin of some tergites and pygidium usually modified, several tergites before ♂ pygidium largely crenulate, ♂ pygidium with a paramedian pair of distinct knobs at a centrally emarginate or nearly straight caudal edge. Anterior telopods often flattened sagittally, sometimes also inflated, but usually devoid of mesal outgrowths. Posterior telopods devoid of trichoteles and each forming a distinct apical pincer (either T2 and T4, when T3 rudimentary, or T2 and T3=4, when true T3 fully suppressed). Eastern Mediterranean | Typhloglomeris |
– | Caudal margin of some tergites and/or pygidium modified, several tergites before ♂ pygidium glabrous, not crenulate, but sometimes drawn caudad into small central lobes, while ♂ pygidium with a centrally emarginate caudal margin and only sometimes with a paramedian pair of indistinct knobs at rear edge. Anterior telopods flattened sagittally, with evident mesal outgrowths. Posterior telopods with both a trichostele retained on T1 and an indistinct apical pincer (T2 and T3). Southern China and northern Vietnam | Tonkinomeris |
Finding a glomeridellid genus in southern China and northern Vietnam is indeed remarkable, as the geographically closest record belongs to Typhloglomeris martensi (Golovatch, 1981), from Hyrcania, southwesternmost Caspian Sea coast within both the Republic of Azerbaijan and northwestern Iran (
The above picture not only so considerably extends the known distribution area of Glomeridellidae to the east, but it also demonstrates the extent to which the millipede fauna of China is still understudied, as well as the possible roles that the Sino-Himalayan (= southern Chinese) and/or Oriental faunogenetic centres could have played in the origins of the Euro-Mediterranean diplopod fauna (
More information is necessary, especially phylogenetic reconstructions, in order to assess the remarkable disjunction of the Glomeridellidae and both its biological and spatial evolution. Further conclusions must be deferred until more evidence, both morphological and molecular, becomes available. New Glomerida are still being actively found and described from various places in Asia!
We are most grateful to Zhengkun Hu, Administrative Bureau of Fanjingshan National Nature Reserve, for collecting and rendering his material to us for study. The first author was sponsored by the National Natural Science Foundation of China (grant no. 31801956). The second author was partly supported by the Presidium of the Russian Academy of Sciences, Programme No. 41 “Biodiversity of natural systems and biological resources of Russia”.
We are very grateful to Dragan Antić and Thomas Wesener, the two reviewers who positively evaluated our advanced manuscript and suggested a number of improvements to the final version.