Research Article |
Corresponding author: Wisut Sittichaya ( wisut.s@psu.ac.th ) Academic editor: Dragan Antić
© 2022 Natdanai Likhitrakarn, Sergei I. Golovatch, Wisut Sittichaya.
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:
Likhitrakarn N, Golovatch SI, Sittichaya W (2022) Review of the millipede genus Malayorthomorpha Mršić, 1996 (Diplopoda, Polydesmida, Paradoxosomatidae), with descriptions of two new species from Thailand and a key to its species. ZooKeys 1118: 1-19. https://doi.org/10.3897/zookeys.1118.89593
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The millipede genus Malayorthomorpha Mršić, 1996, so far monospecific and previously known only from Park Belum, Perak State, northern Malaysia, is recorded from a mountain in Betong District, Yala Province, southern Thailand for the first time, being represented there by two new species: M. halabala sp. nov. and M. hulutbeeda sp. nov. Both new species are found to occur syntopically and can be assumed as narrowly endemic to the Titiwangsa Mountain Range which begins in southern Thailand, crosses the Malaysian border, and extends into east and west coast regions of the Malay Peninsula. In addition, the generic diagnosis is slightly updated, and a key to all three species is provided.
Malaysia, Malayorthomorpha halabala sp. nov., Malayorthomorpha hulutbeeda sp. nov., Orthomorphini, taxonomy
The millipede genus Malayorthomorpha Mršić, 1996 was established for a single, and type species, Malayorthomorpha siveci Mršić, 1996, based on two males from northern Malaysia (
Thailand is located in the central part of mainland Southeast Asia within two significant biodiversity hotspots, Indo-Burma and Sundaland (
However, there are still some areas that have never been explored and prospected sufficiently well for millipedes, such as three southern border provinces within the Malay Peninsula: Pattani, Narathiwat and Yala. Some Diplopoda have only been documented from the Yala and Narathiwat provinces, while the Pattani Province has remained devoid of any millipede records (
Localities of millipede species recorded from the Yala and Narathiwat provinces, Thailand.
No. | Species | Locality | Remark |
---|---|---|---|
Order Sphaerotheriida | |||
1 | Sphaerobelum meridionalis Bhansali & Wesener, 2022 | Yala Province, Than To District, Bang Lang National Park (Than To Waterfall), 150 m a.s.l., 6°11'47.5"N, 101°09'50.9"E ( |
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Order Spirostreptida | |||
2 | Anurostreptus barthelemyae Demange, 1961 | Yala Province, Bang Lang National Park, 6°04'N, 101°11'E; Narathiwat Province, Khao Mala ( |
Originally described from Peninsular Malaysia ( |
3 | Thyropygus aterrimus (Pocock, 1889) | Yala Province, Bang Lang National Park, 6°11'47.5"N, 101°09'50.9"E; Naratiwat Province, Waeng District, Hala-Bala WS Research Station, 5°47'44.8"N, 101°50'4.2"E ( |
Also known from Myanmar ( |
4 | Thyropygus floweri (Demange, 1961) | Bukit Jalor (=Yala) (Demange, 1961); Yala Province, Bang Lang National Park, 6°04'12"N, 101°11'18"E ( |
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Order Polydesmida | |||
5 | Eutrichodesmus cavernicola (Sinclair, 1901) | Yala Province, Mueang Yala District, Wat Khuhapimuk (adjust the precise position of |
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6 | Anoplodesmus malayanus (Golovatch, 1993) (E) | Records from Thailand: Yala Province, Bang Lang National Park, 6°04'N, 101°11'E, <400m ( |
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7 | Desmoxytes delfae (Jeekel, 1964) | Yala Province, Bang Lang National Park, lowland rainforest, 6°4'N, 101°11'E ( |
The species was found in abundance in the provinces of Surat Thani, Krabi, Nakhon Si Thammarat, Phatthalung, Trang, Satun, and Songkhla, which cover the majority of southern Thailand ( |
8 | Haplogonomorpha gogalai Mršić, 1996 | Yala Province, Bang Lang National Park, 6°04'N, 101°11'E, <400m ( |
This monotypic species was originally described from Peninsular Malaysia ( |
9 |
Orthomorpha banglangensis |
Yala Province, Bang Lang National Park, 6°04'N, 101°11'E ( |
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10 | Substrongylosoma moniliforme Golovatch, 1993 | Yala Province, 20 km south of Tham To, 5°50'N, 101°10'E, 200 m; Yala Province, Bang Lang National Park, 6°04'N, 101°11'E, 400 m a.s.l. ( |
Luckily, we have recently been privileged to survey an evergreen forest in the Betong District, Yala Province near the Thai-Malaysia border during the rainy season. Based on morphological examinations of the new specimens, we are able to herewith describe and illustrate two new species of the genus Malayorthomorpha which is formally reported from Thailand for the first time.
New material was collected in a montane forest at a rather high elevation near the Thai-Malaysian border. The specimens collected were euthanized by a two-step method following the AVMA Guidelines for the Euthanasia of Animals (
In the synonymy sections, D stands for the original description and/or subsequent descriptive notes, K for the appearance in a key, L for the appearance in a species list, while M for a mere mention.
The terminology concerning gonopodal and somatic structures mostly follows
g groove, a distinct groove line running parallel to the solenomere, clearly seen in mesal view
ll lamina lateralis, a flat lobe in the distal part of the gonopod
lm lamina medialis, a large part located distally on the gonopod, tapered apically and unciform
sl solenomere, usually a long and flagelliform structure originating at the base of the solenophore
sph solenophore (= tibiotarsus), the apical part of the telopodite, consisting of a lamina lateralis and a lamina medialis
The Animal Care and Use Protocol Review No. 1723018 was applied.
Coordinates and elevations were recorded by Garmin GPSMAP 60 CSx and Garmin eTrex 30 using the WGS84 datum and subsequently double-checked with Google Earth ver. 7.3.4
Subfamily Paradoxosomatinae Daday, 1889
Malayorthomorpha Mršić, 1996: 139 (D).
Malayorthomorpha
–
Body medium-sized to large (ca. 24–41 mm long, ca. 1.2–2.7 mm wide), with 20 segments. Paraterga from poorly to rather well developed, without lateral incisions. Transverse metatergal sulcus distinct. Leg relatively long and slender, without modifications. ♂ tarsal brushes absent. Sternal lobe between ♂ coxae 4 present, other sternites unmodified.
Gonopods rather simple to relatively complex; coxites elongate, subcylindrical, sparsely setose distoventrally, without tubercles; prefemoral (= setose) part of telopodite moderate to relatively large, 1/3–1/2 as long as acropodite; femorite moderately long and stout, slightly curved, devoid of a distinct distolateral sulcus demarcating a postfemoral part; a well-developed lamina medialis and a hypertrophied lamina lateralis of solenophore; the latter subterminally with a long, distally pointed and curved lobe broadened at base and protecting the tip of a curved solenomere. Apex of solenophore subquadrate. Solenomere flagelliform, starting about level to demarcation cingulum between femorite and solenophore, seminal groove running entirely or mostly mesally along an excavate femorite.
Malayorthomorpha siveci Mršić, 1996, by original designation.
As noted earlier (
1 | Sternal lobe between ♂ coxae 4 linguiform with a rounded tip (Figs |
Malayorthomorpha hulutbeeda sp. nov. |
– | Sternal lobe between ♂ coxae 4 deeply notched medially (Figs |
2 |
2 | Pleurosternal carinae present until segment 11. Sternal lobe between ♂ coxae 4 with a pair of small cones near base (Figs |
Malayorthomorpha halabala sp. nov. |
– | Pleurosternal carinae present until segment 5. Sternal lobe between ♂ coxae 4 without cones near base (Fig. |
Malayorthomorpha siveci |
Malayorthomorpha siveci Mršić, 1996: 139 (D).
Malayorthomorpha siveci
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This species was described from Park Belum, 5°30'7"N, 101°26'21"E, ca. 320–350 m a.s.l., Hulu (Sungani), Perak, Malaysia (
Malayorthomorpha siveci Mršić, 1996, ♂ holotype A, B anterior part of body, lateral and dorsal views, respectively C anal segment, ventral view D sternal process and left anterior leg of body segment 5, suboral view E–G right gonopod, mesal, lateral and suboral views, respectively. Photos not to scale (after
Holotype
: Thailand – Yala Province • ♂; Betong District, hill in evergreen forest, on forest floor; 1440 m a.s.l.; 5°55'N, 101°26'E; 22 May 2021; Wisut Sittichaya leg.;
This new species seems to be particularly similar to M. siveci Mršić, 1996, with which it shares most of the gonopodal characters. It differs from M. siveci by the wider body, 2.7–3.2 mm (vs smaller, 1.2 mm), the colour pattern which is uniformly red brown with lighter red brown paraterga (Fig.
Length 29.3 (♂) or 36.2 mm (♀), width of midbody pro- and metazonae 2.1 and 2.7 mm (♂) or 2.7 and 3.2 mm (♀), respectively.
Colouration of live animal rusty red (Fig.
Malayorthomorpha halabala sp. nov., ♂ holotype A, B anterior part of body, dorsal and lateral views, respectively C, D segments 10 and 11, dorsal and lateral views, respectively E–G posterior part of body, lateral, dorsal and subventral views, respectively H, I sternal cones between coxae 4, subcaudal and sublateral views, respectively.
Clypeolabral region sparsely setose; epicranial suture distinct. Antennae long, extending caudally past metaterga 5 (♂) or metaterga 3 (♀) when stretched dorsally. In width, segment 3 < 4 = collum < segment 2 = head < segment 5 < 6–17, body gently and gradually tapering thereafter.
Collum with three transverse rows of setae: 4+4 in anterior, 2+2 in intermediate, and 3+3 in posterior row, all mostly abraded, but still traceable as insertion points; lateral incisions absent; caudal corner of paraterga very broadly rounded, declined ventrad, produced slightly past rear tergal margin (Fig.
Tegument generally smooth and shining, prozonae finely shagreened, metaterga finely leathery and faintly rugulose (Fig.
Paraterga rather well developed (Fig.
Calluses on paraterga rather narrow, delimited by a sulcus fully on dorsal side and in about posterior 2/3 on ventral side; on poreless rings more narrow than on pore-bearing ones in dorsal view (Fig.
Transverse sulcus usually distinct (Fig.
Epiproct (Fig.
Sterna sparsely setose, shining, cross-impressions shallow, without modifications; a single, linguiform, medially rather deeply notched sternal lobe between ♂ coxae 4, with a pair of small cones laterally near base (Fig.
Gonopods (Figs
To emphasize Hala-Bala Wildlife Sanctuary, the type locality. Noun in apposition.
A comparison of these two species shows only a few differences, but they are sufficient to distinguish both. The type locality of M. siveci, Park Belum, is located quite far away (ca. 50 km) from this new place. In addition, because the elevations between the two localities are greater than 1000 meters above sea-level, it seems improbable that the species is one and the same. Consequently, we conclude that the two are obviously distinct species.
The specimens were collected in a primary sub-elfin montane forest with no significant disturbance due to human activity, in a high mountainous area of southernmost Thailand (Fig.
Holotype
: Thailand – Yala Province • ♂; Betong District, elfin montane forest (Malaya Phytochorion province); 1430 m a.s.l.; 25 May 2022; Wisut Sittichaya leg.;
This new species is distinguished from its two congeners in sternal process between male coxae 4 linguiform with a rounded tip, and lamina lateralis of gonopodal solenophore triangular, apically bifid and protruded laterally.
Length of holotype 31.5 mm, width of midbody pro- and metazonae 2.7 and 3.0 mm, respectively.
Colouration of alcohol material after one week of preservation dark red brown (Fig.
Malayorthomorpha hulutbeeda sp. nov., ♂ holotype A, B anterior part of body, dorsal and lateral views, respectively C, D segments 10 and 11, dorsal and lateral views, respectively E–G posterior part of body, lateral, dorsal and subventral views, respectively H, I sternal cones between coxae 4, subcaudal and sublateral views, respectively
All characters as in M. halabala sp. nov., except as follows.
Antennae rather long, extending caudally past metaterga 4 when stretched dorsally. Collum with three transverse rows of setae: 4+4 in anterior, 2+2 in intermediate, and 3+3 in posterior row; with a small lateral setigerous incision near midway (Fig.
Paraterga 2 broad, anterior edge angular and rounded, lateral edge with a small notch at about 1/4 in front of caudal corner (Fig.
Transverse sulcus distinct (Fig.
Hypoproct roundly subtriangular, setigerous knobs at caudal edge very small and well-separated (Fig.
Sterna moderately setose, shining, cross-impressions shallow, without modifications; an entire, large, linguiform, sternal lobe between ♂ coxae 4, with a pair of small denticles laterally near base (Figs
Gonopods (Figs
To emphasize “hulutbeeda” which means “flat-back millipede” in Malay dialect, a noun in apposition. A Malay dialect language is mainly used in three provinces of southern Thailand where the holotype was obtained.
This species was found living together with M. halabala sp. nov. Moreover, according to our observations, they may even occur syntopically, sharing the same habitat: leaf litter surface, branches of trees and tree trunks.
In accordance with the previous observations of related genera such as Orthomorpha Bollman, 1893, Desmoxytes Chamberlin, 1923 and Tylopus Jeekel, 1968, the coexistence of congeners is quite common to come across in Paradoxosomatidae generally and Orthomorphini in particular. So the syntopy of Malayorthomorpha halabala sp. nov. and M. hulutbeeda sp. nov. is not unusual. For example, Desmoxytes planata (Pocock, 1895) was discovered beside D. octoconigera Srisonchai, Enghoff & Panha, 2018, D. golovatchi Srisonchai, Enghoff & Panha, 2018 and D. purpurosea Enghoff, Sutcharit & Panha, 2007 in several places (
Malayorthomorpha species are presently endemic to southern Thailand and northern Peninsular Malaysia, both of which are located within the Titiwangsa Mountain Range, which is known as Peninsular Malaysia’s backbone and longest mountain ridge. It begins in the north of southern Thailand, crosses the Malaysian border, enters the Negeri Sembilan valley, and terminates in the south near Jelebu, Negeri Sembilan (
This research was encouraged and supported by Professor Dr Somsak Panha, Animal Systematics Research Unit, Department of Biology, Faculty of Science, Chulalongkorn University. One of us (SIG) was partly supported by the Presidium of the Russian Academy of Sciences, Program No. 41 “Biodiversity of Natural Systems and Biological Resources of Russia”. We are most grateful to Mr Sunate Karapan and all members of Hala-Bala Wildlife Research Station for facilitating us in the collection of material. Special thanks go to Assistant Professor Dr Surasak Kuimalee, Science and Technology Service center, Faculty of Science, Maejo University, for skillfully taking SEM micrographs.