Research Article |
Corresponding author: Chanaporn Suttinun ( chanaporn.s@cmu.ac.th ) Academic editor: Eduardo Dominguez
© 2023 Sedtawut Kwanboon, Boonsatien Boonsoong, Chanaporn Suttinun.
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:
Kwanboon S, Boonsoong B, Suttinun C (2023) Taxonomic review of the Oriental genus Polyplocia Lestage, 1921 (Ephemeroptera, Euthyplociidae), with two new records for Thailand. ZooKeys 1179: 197-217. https://doi.org/10.3897/zookeys.1179.107312
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Previously, the euthyplociid mayfly from Thailand was reported as Polyplocia spp. without designation to any nominal species. In this study, the genus Polyplocia Lestage, 1921 in Thailand was reviewed. Two species are recognized: Polyplocia orientalis Nguyen & Bae, 2003 and P. nebulosa Gonçalves & Peters, 2016. This is the first report of P. nebulosa in Continental Asia. Cytochrome c oxidase subunit I (COI) data and illustrations based on nymphal characters were used to confirm two different species in Thailand. Additional morphological characteristics of the nymph and eggs of the two species from Thailand are also shown in detail. The taxonomic status of Polyplocia in the Oriental region is reviewed. Keys to known nymphal and imaginal stages are provided and the distribution of Polyplocia in the Oriental region is discussed.
Burrowing mayfly, Continental Asia, distribution, habitat, Insular Asia, taxonomy
To date, the genus Polyplocia is composed of four valid species: P. vitalisi reported only in an adult stage, P. campylociella reported in adult stage with possible nymphal stage, P. orientalis reported in both stages and P. nebulosa reported in adult stage with a possible nymphal stage. The distribution of this genus encompasses the Oriental Realm (
The specimens were collected by hand-picking from headwater streams in the northern and the western parts of Thailand. (Table
Species | Locality | GPS coordinates |
---|---|---|
Polyplocia orientalis | Chiang Rai (CR) | 19°26'53.7"N, 99°41'83.6"E |
Chiang Mai (CM) | 19°19'31.1"N, 99°58'84.6"E | |
Polyplocia nebulosa | Kanchanaburi (KN) | 14°33'10.8"N, 98°33'94.3"E |
Phetchaburi (PE) | 12°28'53.2"N, 99°15'23.0"E | |
Polyplocia campylociella | Sarawak, Malaysia | 4°02'51.0"N, 114°50'11.9"E |
Selected specimens were dissected for DNA extraction. Total DNA was extracted using a genomic DNA purification kit (NucleoSpin, Macherey-Nagel, Germany), following the manufacturer’s protocol. The COI amplification was performed using LCO1490 and HCO2198 (
Species | Locality | Code | GenBank # | GenSeq Nomenclature |
---|---|---|---|---|
P. nebulosa | Kanchanaburi, Thailand | PC02KN | OR366860 | genseq-4 COI |
Phetchaburi, Thailand | PC01PE | OR366862 | genseq-4 COI | |
Kanchanaburi, Thailand | PC08PE | OR366863 | genseq-4 COI | |
P. orientalis | Chiang Rai, Thailand | PC04CR | OR366857 | genseq-4 COI |
Chiang Rai, Thailand | PC05CR | OR366858 | genseq-4 COI | |
Chiang Rai, Thailand | PC06CR | OR366861 | genseq-4 COI | |
Chiang Mai, Thailand | PC01CM | OR366859 | genseq-4 COI | |
Vietnam | OP347109 | |||
Yunnan, China | OP962407 | |||
P. campylociella | Sarawak, Malaysia | OR366864 | genseq-4 COI |
The material was deposited in the collection of the
Zoological Museum at Kasetsart University in Bangkok, Thailand (ZMKU) and the
Veterinary Anatomy and Pathology Museum, Chiang Mai University, Thailand (
We followed all guidelines of the Animal Ethics Committee of Kasetsart University (approval no. ACKU61-SCI-029) for collecting the mayfly specimens.
Nymphs of Polyplocia spp. from northern of Thailand of
Family Euthyplociidae Edmunds & Traver, 1954
Polyplocia
Lestage, 1921: 212 (Type: Polyplocia vitalisi);
Imago: i) transverse pronotum, ii) forewing with MA fork at same level as Rs fork, and at least one intercalary vein in the cubital field with its base connected to CuP, iii) forceps with only one segment, and iv) three caudal filaments on abdomen (
Polyplocia vitalisi Lestage, 1921: 212, original description (male imago).
Polyplocia vitalisi
(
Polyplocia vitalisi
(
Polyplocia vitalisi
(
None.
Imago: i) transparent wing, ii) membrane of forewing with purplish colour on C and Sc fields, iii) abdominal sterna without marking, and vi) penis lobe with a smooth apical border (
Male imago. See
Female imago. Unknown.
Nymph. Unknown.
Tonkin (Vietnam).
This species was described based on one male imago from Tonkin, Vietnam.
= P. crassinervis Ulmer, 1939 (
Polyplocia campylociella Ulmer, 1939: 468, figs 10–11, original description (female subimago).
Polyplocia crassinervis Ulmer, 1939: 470, figs 12–15, male subimago).
Polyplocia crassinervis
(
Polyplocia campylociella
(
Polyplocia campylociella
(
Polyplocia campylociella
(
Malaysia: One immature nymph in alcohol, deposited in ZMKU, Sarawak, Marudi district, Miri division, Gunung Mulu, Sungai Paku, 4°02'51.0"N, 114°50'11.9"E, ~240 m, 13.VI.2023, B. Boonsoong leg.
The imago of P. campylociella can be distinguished from those of other Polyplocia species based on the following characteristics: i) wings with dark clouds around cross veins and margins, ii) membrane of forewing with little dark colour on C and Sc fields, iii) styliger plate rounded, and iv) penis V-shaped without dorsal spine (
Male imago. See
Female imago. See
Nymph. See
Malaysia (Sarawak), Indonesia (Sambas).
The possible nymph of P. campylociella was described based on one immature nymph by
Polyplocia nebulosa Gonçalves & Peters, 2016: 554, figs 1–21, original description (male and female imago, female subimago, egg, possible nymph).
Thailand: Two nymph in alcohol, deposited in ZMKU, Kanchanaburi province, Thong Pha Phum district, Pat Sadu Klang, 14°33'10.8"N, 98°33'94.3"E, 349 m, 20.II.2016, B. Boonsoong leg. Three nymphs in alcohol, deposited in ZMKU, Phetchaburi province, Kaeng Krachan district, Ban Krang river, 12°28'53.2"N, 99°15'23.0"E, 386 m, 11.II.2023, A. Vitheepradit leg.
Imago: i) wings with longitudinal veins light brown and cross veins brown, cross veins with narrow dark brown clouds and margins tinged with brown, ii) sterna II–IX with a pair of blackish brown anterolateral marks, iii) penes broad, T-shaped, fused, with medial groove extending from apex to half-length of penes; large laterally projecting lobes apically rounded with a small dorsolateral spine; basal outer margin of each lobe sclerotized, iv) styliger plate short and straight, not projected posteriorly, and v) eggs 265–267 μm in length and 170–186 μm in width, barrel shaped, without polar caps or other attachment structures, with one visible micropyle and chorion forming an irregular mesh with raised ridges, mesh size from 3.8–8.0 μm (
Male imago. See
Female imago. See
Nymph. See
Mandibular tusks (Fig.
Malaysia (Sabah), Thailand (Kanchanaburi, Phetchaburi).
Polyplocia orientalis Nguyen & Bae, 2003a: 280, figs 1–2, original description (nymph).
Polyplocia orientalis
(
Polyplocia
spp. (
Polyplocia orientalis
(
Thailand: Eleven nymphs in alcohol, deposited in ZMKU, Chiang Rai province, Phan district, Pu Kaeng waterfall, 19°26'53.7"N, 99°41'83.6"E, 540 m, 5.III.2021, S. Kwanboon leg. Three nymphs in alcohol, deposited in
Imago: i) membrane of wings transparent and colourless, and ii) T-shaped male penis with apical depression on both lobes (
Male imago. See
Female imago. See
Nymph. See also
(Thai specimens). Nymph. Male body length 17.22 mm; cerci length 11.78 mm; median filament length 10.5 mm. Female body length 27.9 mm; cerci length 18.5 mm; median filament length 16.2 mm.
Head. Length 2× of maximum width; narrower than pronotum. Compound eye black on dorsolateral margin. Antenna 8.8 mm in length; scape with at least three short setae.
Mouthpart. Labrum (Fig.
Legs. Ratio of forelegs: midlegs: hindlegs 1:0.7:0.7; ratio of foreleg segments 1:1.2:0.7:0.4; ratio of midlegs segments 1:1:0.4:0.2 with moderately developed setae; ratio of hindleg segments 1:0.6:0.2:0.1, lack setae on femora.
Female subimago. Egg. (Fig.
In this study, Thai Polyplocia orientalis showed some variation in these characters combined: i) Labrum slightly concave on anterior margin, nearly straight, ii) tusks cylindrical pointed apically, strongly arched inward (18.6° curvature) and outer margin with 7–9 larger spines on 1/3 of tusk length distally, and iii) eggs oval-shaped with two visible micropores.
China (Yunnan), Vietnam (Dak Lak, Lam Dong, Thua Thien Hue), Thailand (Chiang Rai, Chiang Mai, Phrae, Phayao, Nan) (
1 | Abdominal sterna without a pair of anterolateral black marks (Fig. |
P. orientalis Nguyeun & Bae, 2003 |
– | Abdominal sterna with a pair of anterolateral black marks (Fig. |
P. nebulosa Gonçalves & Peters, 2016 / P. campylociella Ulmer, 1939* |
*The details of nymph of P. campylociella are insufficient because of the limited description by
1 | Veins with dark brown clouds around cross veins and margins of wings with brownish tinge; membrane of forewing without purplish color on C and Sc fields (Sc field may be a little darker); abdominal sterna with a pair of blackish marks on anterolateral margins | 2 |
– | Veins without dark clouds around cross veins and wing margins translucent; membrane of forewing colored only on C and Sc fields, purplish; abdominal sterna without markings | 3 |
2 | Styliger plate rounded and projected, penis V-shaped, penes apparently without dorsal spine | P. campylociella Ulmer, 1939 |
– | Styliger plate not projected, short and straight, penis T-shaped, each lobe of penes with small dorsal spine laterally directed | P. nebulosa Gonçalves & Peters, 2016 |
3 | Both penis lobes have an apical depression | P. orientalis Nguyen & Bae, 2003 |
– | Penis lobes with smooth apical margin | P. vitalisi Lestage, 1921 |
The genus Polyplocia was collected at an altitude of 300–800 metres above sea level; Polyplocia nebulosa was found in a headwater stream in the forest, while P. orientalis was found in a headwater stream and a limestone waterfall quite disturbed by tourist activities. The nymphs were found on the underside of cobbles in slow-flowing waters at the margins of the stream (Figs
The partial sequences of the mitochondrial COI gene (658 bp) of the two species found in Thailand and P. campylociella from Malaysia were obtained from specimens of each locality (Table
Genetic distances (COI) between sequenced specimens using the Kimura 2-parameter.
Species | 1 | 2 | 3 | 4 | 5 | |
---|---|---|---|---|---|---|
1 | P. orientalis (Thailand) | 0.00–10.7 | ||||
2 | P. orientalis (China) | 6.23–7.41 | – | |||
3 | P. orientalis (Vietnam) | 9.51–10.6 | 10.0 | – | ||
4 | P. nebulosa (Thailand) | 17.7–23.6 | 20.7–21.9 | 16.7–20.1 | 0.15–2.02 | |
5 | P. campylociella (Malaysia) | 19.1–20.6 | 19.8 | 21.7 | 20.7–23.1 | – |
6 | Potamanthus formosus | 22.8–24.1 | 23.8 | 23.0 | 23.0–24.3 | 25.2 |
COI sequences analysis was built by maximum likelihood (ML) using MEGA11 (Fig.
Specimens of the Polyplocia from Thailand were studied based on the following nymphal characters defined by
Characters | P. orientalis Nguyen & Bae, 2003 | P. nebulosa Gonçalves & Peters, 2016 | P. campylociella Ulmer, 1939 | |
---|---|---|---|---|
Head | antenna length vs. tusk length | longer | longer | slightly longer |
Labrum | anterior margin | medially slightly concave with shallow emargination | medially concave with shallow emargination | medially concave (from fig. 1b) |
Mandibular tusks | length of tusks vs. length of head | 2×–3× | 2× | ? |
inward curvature | 18.6°–21.3° | 20.7° (in this study) | ? | |
number of spines | 3–12 | 8–9 (fig. 18 |
? | |
presence of large spines | Apical 1/3 | Apical 1/2 | Apical 1/3 ( |
|
Legs | length of apical spine of the foretibiae vs. length of the foretarsi | 1/3–1/4 | less than 1/2, 1/3 (in this study) | ? |
Abdomen | sterna | whitish | a pair of anterolateral black marks | a pair of anterolateral black marks |
Winged stage | associated | yes | possible nymph | possible nymph |
eggs shape (subimago) | oval; barrel | barrel | ? | |
eggs length vs. width | 1.3× | 1.6× | ? | |
number of micropores | 2 | 1 | ? | |
Distribution | Vietnam, China, Northern Thailand | Borneo, Malaysia, Western Thailand | Borneo, Malaysia | |
References |
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The egg structure of all Polyplocia species has a similar chorionic surface pattern that forms an irregular mesh with raised ridges; however, we found small differences between the eggs of Thai and Chinese specimens of P. orientalis. The specimen from Thailand is oval-shaped, with two visible micropores, while P. orientalis from China and Vietnam has a barrel-shaped egg with no mention of a micropore (
The first molecular study of the genus Polyplocia was conducted by
Polyplocia nymphs from Thailand were mentioned by
The distribution of the genus Polyplocia Lestage, 1921 in the Oriental region is shown in Fig.
Our study allows us to conclude that the genus Polyplocia in Thailand is represented by two species, P. orientalis and P. nebulosa, based on a combination of different morphological characters, egg characters and molecular evidence. We have reported the first nominal species records of this family in Thailand and expanded the distribution of these two species. The distribution of P. orientalis in Thailand is limited to the northern parts and mainland Asia, while the distribution of P. nebulosa extends from Insular Asia to Continental Asia, in western Thailand in our study. We expect to find a broader distribution of this genus in Thailand, especially in the southern and the eastern parts, as we gain a more in-depth understanding of the distribution pattern of this genus in the Oriental region.
This research was partially supported by Chiang Mai University, the Faculty of Veterinary Medicine, Chiang Mai University, and the Centre of Excellence on Biodiversity (BDC) Office of Higher Education Commission. We are most grateful to Assistant Professor Dr. Akekawat Vitheepradit (Department of Entomology, Faculty of Agriculture, Kasetsart University) who kindly provide specimens for this study. We are thankful to Dr. Chonlakarn Auychinda (Department of Biology, Faculty of Science, Silpakorn University) for his support with lab work and preparation of the COI barcode. Sarawak Forestry Permission to conduct research on biological resources - Permit SFC.810-4/6/1 (2023) - 023. We are most grateful to our colleagues for assistance during field trips. Further, we would like to thank the Department of Veterinary Biosciences and Veterinary Public Health, Faculty of Veterinary Medicine, Chiang Mai University and Department of Zoology, the Faculty of Science at Kasetsart University in Bangkok for their assistance and use of their facilities. The authors are also grateful to the reviewers for their valuable recommendations and comments on the manuscript.
The authors have declared that no competing interests exist.
No ethical statement was reported.
This research was partially supported by Chiang Mai University for research funding through the Research Center for Veterinary Biosciences and Veterinary Public Health, Faculty of Veterinary Medicine.
Sedtawut Kwanboon contributed in the process of Collected the data; Contributed data or analysis tools; Wrote the paper. Boonsatien Boonsoong contributed in the process of Conceived and designed the analysis; Collected the data; Wrote the paper. Chanaporn Suttinun contributed in the process of Collected the data; Contributed data or analysis tools; Performed the analysis; Wrote the paper.
Sedtawut Kwanboon https://orcid.org/0000-0002-3858-9522
Boonsatien Boonsoong https://orcid.org/0000-0002-8166-0021
Chanaporn Suttinun https://orcid.org/0000-0002-0380-1554
All of the data that support the findings of this study are available in the main text.