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| Nagaxytes gracilis Srisonchai, Enghoff & Panha, N. erecta Srisonchai, Enghoff & Panha, in Srisonchai, Enghoff, Likhitrakarn et Panha, 2018. |
Abstract
The ‘acantherpestes’ group of dragon millipedes, formerly placed in the genus Desmoxytes Chamberlin, 1923, is revised and assigned to the new genus Nagaxytes Srisonchai, Enghoff & Panha gen. nov. Desmoxytes acantherpestes Golovatch & Enghoff, 1994 is the type species of the new genus and is redescribed as N. acantherpestes (Golovatch & Enghoff, 1994) gen. et comb. nov. Three new species are described from Thailand: N. erecta Srisonchai, Enghoff & Panha gen. et sp. nov. and N. gracilis Srisonchai, Enghoff & Panha gen. et sp. nov. from Kanchanaburi Province, and N. spatula Srisonchai, Enghoff & Panha gen. et sp. nov. from Tak Province. All new species are endemic to western Thailand and all are restricted to limestone habitats. Complete illustrations of external morphological characters, an identification key, and a distribution map are provided.
Keywords: endemic; dragon millipede; new species; taxonomy; Thailand
Taxonomy
Class Diplopoda Blainville-Gervais, 1844
Order Polydesmida Pocock, 1887
Suborder Strongylosomatidea Brölemann, 1916
Family Paradoxosomatidae Daday, 1889
Subfamily Paradoxosomatinae Daday, 1889
Tribe Orthomorphini Brölemann, 1916
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| General body characters of Nagaxytes Srisonchai, Enghoff & Panha gen. nov. N. acantherpestes (Golovatch & Enghoff, 1994) gen. et comb. nov., ♂, holotype, Prachuap Khiri Khan Province, Hua Hin District (ZMUC 000101457). A. Entire body. B. Anterior body part. C. Body rings 5–8, showing sternal lobe between coxae 4 and gonopods on ring 7. D. Head and antennae. |
Genus Nagaxytes Srisonchai, Enghoff & Panha gen. nov.
Type species: Desmoxytes acantherpestes Golovatch & Enghoff, 1994
Diagnosis:
The genus Nagaxytes gen. nov. is characterized by:
1. Paraterga subspiniform.
2. Metaterga with 2 rows of tubercles/cones/spines (lateral spines of posterior row very long).
3. Male femora 5 and 6 without modification.
4. Postfemoral part of gonopod conspicuous, demarcated from femur by a deep mesal sulcus and a
shallow/deep lateral sulcus.
5. Lamina lateralis obviously separated from lamina medialis.
6. Lamina medialis long and curved, apically fringed/hooked.
Etymology: ‘Naga’ is a Sanskrit and Pali word, relating to a category of snake-like spirits in Buddhist and Hindu mythology, and refers to the snake-like shape of the lamina medialis of the gonopod; ‘-xytes’ ensures harmony with Desmoxytes (and its synonym Pteroxytes Jeekel, 1980).
Included species (4):
- N. acantherpestes (Golovatch & Enghoff, 1994) gen. et comb. nov.
- N. erecta Srisonchai, Enghoff & Panha gen. et sp. nov.
- N. gracilis Srisonchai, Enghoff & Panha gen. et sp. nov.
- N. spatula Srisonchai, Enghoff & Panha gen. et sp. nov.
Remarks: Srisonchai et al. (2018) proposed to subdivide Desmoxytes sensu Golovatch & Enghoff (1994) into five genera. The ‘acantherpestes’ group (= Nagaxytes) is well-defined by several distinct morphological characters (see diagnosis), especially the distinctive subspiniform paraterga and the very long lamina medialis of the gonopods. Even though the subspiniform paraterga are relatively similar to those of the ‘gigas’ group, the gonopod details are very different.
Distribution and habitat: This genus is known only from the western part of Thailand: Prachuap Khiri Khan Province (Hua Hin and Kui Buri Districts), Kanchanaburi Province (Sai Yok and Thong Pha Phum Districts) and Tak Province (Mae Sot and Umphang Districts) (Fig. 27). All four species seem to be local endemics, highly restricted to limestone habitats, and all have narrow distribution ranges. The specimens were usually found on humid rocks, rock walls, leaf litter or surface roots of trees. Some species can be found syntopically in the same habitat with other dragon millipede species.
Nagaxytes acantherpestes (Golovatch & Enghoff, 1994) gen. et comb. nov.
Diagnosis: Metaterga 4–19 with one row of 2+2 posterior spines (anterior row absent). Similar in this respect to N. gracilis gen. et sp. nov. but differs from this species by having paraterga shorter; degree of elevation of paraterga lower; sternal lobe between male coxae 4 subtrapeziform; lamina lateralis swollen, stout, short.
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| Live photographs and habitat of Nagaxytes erecta Srisonchai, Enghoff & Panha gen. et sp. nov. A. Specimen from Ban Nong Bang, Thailand (♀). B. Mating couple. C. ♂ with parasitic mites. D. Habitat. |
Nagaxytes erecta Srisonchai, Enghoff & Panha gen. et sp. nov.
Etymology The name is a Latin adjective and refers to the erect lamina lateralis of the gonopod telopodite.
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| Nagaxytes gracilis Srisonchai, Enghoff & Panha gen. et sp. nov., ♂, paratype (CUMZpxDGT00095). Watercolour by R. Srisonchai and P. Kriatpraprai. |
Nagaxytes gracilis Srisonchai, Enghoff & Panha gen. et sp. nov.
Etymology The name is a Latin adjective, referring to the slender lamina lateralis of the gonopod telopodite.
Distribution and habitat: Nagaxytes gracilis gen. et sp. nov. is known only from Sai Yok District, Kanchanaburi Province. All specimens were collected on humid rocks, superficial tree roots and litter in limestone habitats. It lives in the same habitat with D. purpurosea, D. golovatchi Srisonchai, Enghoff & Panha, 2018 and N. erecta gen. et sp. nov. (q.v.). The new species occurs in a narrow distribution area along the huge limestone range which is entirely contained within Sai Yok District. We thus consider this species to be endemic to Kanchanaburi Province, Thailand.
Nagaxytes spatula Srisonchai, Enghoff & Panha gen. et sp. nov.
Etymology The name is a Latin noun in apposition, referring to the spatulate lobe on the lamina lateralis.
Distribution and habitat Known only from Tak Province. Almost all specimens were seen crawling on rocks, some on leaf litter in limestone habitats. Some juveniles were collected from the leaf litter (probably in moulting chambers). In the field, the specimens blended perfectly with brown rocks and leaf litter.
Ruttapon Srisonchai, Henrik Enghoff, Natdanai Likhitrakarn and Somsak Panha. 2018. A Revision of Dragon Millipedes II: The New Genus Nagaxytes gen. nov., with the Description of Three New Species (Diplopoda, Polydesmida, Paradoxosomatidae). European Journal of Taxonomy. 462; 1–44. DOI: 10.5852/ejt.2018.462
