Mongolodiap omus nakhonphanomensis sp. no . (Copepoda,
Calanoida, Diap omidae) om no h-eas e n Thailand, wi h a no e
on M. pec inidac ylus (Shen & Tai, 1964)
San i Wa i oy am1, Piya hida Monongde n1, Kamonwan Koompoo 2
1 Di ision o Biology, Facul y o Science, Nakhon Phanom Uni e si y, Nakhon Phanom 48000, Thailand
2 DZVA Uni , Walai Rukha ej Bo anical Resea ch Ins i u e, Mahasa akham Uni e si y, Maha Sa akham 44150, Thailand
h ps://zoobank.o g/101DA9B5-8A4E-446F-95C9-E8B64A6D4FEF
Co esponding au ho : San i Wa i oy am ([email p o ec ed])
Academic edi o : Kay Van Damme ♦
Recei ed
10 June 2025 ♦
Accep ed
18 Sep embe 2025 ♦
Published
8 Oc obe 2025
Abs ac
A new species o diap omid copepod, Mongolodiap omus nakhonphanomensis sp. no ., is desc ibed om su ace wa e bodies in
Nakhon Phanom P o ince, no h-eas e n Thailand. The new species is assigned o he M. mephis opheles (B ehm, 1933) species
g oup and is mo phologically mos simila o M. pec inidac ylus (Shen & Tai, 1964), a a e species in Thailand. I can be dis in-
guished om M. pec inidac ylus by he ollowing cha ac e s: I) In emales, he new species has asymme ical la e al wings on pedi-
ge 5 and he second exopod o he i h leg, whe eas M. pec inidac ylus (Shen & Tai, 1964) shows symme y in hese s uc u es; II)
he emale o he new species has a sho e and mo e obus se a on he second exopod o he i h leg compa ed o ha o M. pec in-
idac ylus; III) in males, he new species lacks a spinula ow on he basis o he igh i h leg, which is p esen in M. pec inidac ylus;
IV) he second exopod o he male i h leg in he new species is dis ally expanded, whe eas i is oblong in M. pec inidac ylus; V)
he la e al spine o he second exopod o he male i h leg is ben ou wa ds in he new species, whe eas i is s aigh in M. pec in-
idac ylus. A b ie e-desc ip ion o M. pec inidac ylus and a compa ison wi h he new species a e p o ided. This disco e y aises
he numbe o ecognised species in he genus Mongolodiap omus o i een wo ldwide. A biogeog aphical map is also p esen ed.
Key Wo ds
Endemic species, Indo-malayan ealm, M. pec inidac ylus, Songkh am Ri e Basin
In oduc ion
The genus Mongolodiap omus Kie e , 1937 is p ima i-
ly dis ibu ed in inland egions o Sou heas Asia (SEA)
and ep esen s he mos di e se diap omid genus in Thai-
land (Sanoamuang and Koompoo 2024). Six species
ha e mo e ex ensi e anges, eaching no hwa ds in o
sou h China (Guangdong, Guangxi and Hainan P o inc-
es): M. bi ulai (Rylo , 1923), M. calca us (Shen & Tai,
1965), M. o mosanus Kie e , 1937, M. gladiolus (Shen
& Lee, 1963), M. pec inidac ylus (Shen & Tai, 1964) and
M. uenoi (Kikuchi, 1936). Amongs hese, only M. bi ulai
(Rylo , 1922) has been epo ed as a no h as cen al
China (Hunan P o ince), no h China (Hebei and Hei-
longjiang P o inces) and eas China (Fujian, Jiangsu and
Zhejiang P o inces), as well as Taiwan (Li e al. 2018).
In addi ion, h ee species ha e been eco ded om ca e
habi a s: M. bo uli e (Kie e , 1974) and M. malaindosin-
ensis (Lai & Fe nando, 1978) (Thailand) and M. bi ulai
(Rylo , 1923) (China) (Li e al. 2018; Wa i oy am 2021).
Two species emain doub ul and a e subjec o di -
e ing opinions amongs axonomis s ega ding whe he
hey ep esen dis inc species o a e synonyms, name-
ly M. bi ulai and M. o mosanus (Li e al. 2018; Sano-
amuang and Wa i oy am 2018; Ranga Reddy e al. 2000;
Sanoamuang and Koompoo 2024). Examina ion o ma-
e ial om bo h species is equi ed in u u e s udies o
cla i y hei axonomic s a us. Due o he lack o speci-
Zoosys . E ol. 101 (4) 2025, 1965–1983|DOI 10.3897/zse.101.161679
Copy igh Wa i oy am, S. e al. This is an open access a icle dis ibu ed unde he e ms o he C ea i e Commons A ibu ion License (CC BY 4.0), which pe mi s un es ic ed use,
dis ibu ion, and ep oduc ion in any medium, p o ided he o iginal au ho and sou ce a e c edi ed.
zse.penso .ne
Wa i oy am, S. e al.: A new species o Mongolodiap omus Kie e , 1938 om no h-eas e n Thailand
1966
men examina ion and he absence o de ailed published
desc ip ions suppo ing hei s a us, we ollow he Wo ld
Copepoda Da abase in ecognising hem as dis inc spe-
cies in he p esen s udy (Wal e and Boxshall 2025).
Thus, he e a e cu en ly 14 p e iously known species
wo ldwide, including en eco ded om Thailand, wi h
he excep ion o M. bi ulai, M. o mosanus, M. gladiolus
and M. mephis opheles (B ehm, 1933) (Sanoamuang and
Koompoo 2024; Wal e and Boxshall 2025).
Du ing ou examina ion o samples collec ed om
ibu a ies o he Mekong Ri e Basin in Thailand, eigh
known and one undesc ibed species o Mongolodiap o-
mus we e eco ded (Koompoo and Wa i oy am 2025).
Mos o Mongolodiap omus species p e iously epo ed
om he coun y, excep M. phu akaensis Sanoamuang &
Koompoo , 2024, we e ound du ing his ield ip, p o-
iding an excellen oppo uni y o an in ensi e axonom-
ic s udy. This esul ed in clea mo phological di e en ia-
ion amongs closely- ela ed species, along wi h changes
in species composi ion and dis ibu ion (Koompoo and
Wa i oy am 2025). These indings led o he desc ip ion
o a new species, as well as he eco ding o M. pec in-
idac ylus (Shen & Tai, 1964), a a e species obse ed
in he p esen s udy. A biogeog aphic map o he genus
Mongolodiap omus is also p esen ed, based on a ailable
published li e a u e.
Ma e ials and me hods
Si e desc ip ion
The Nawa Dis ic , si ua ed in he wes e nmos pa o
he Nakhon Phanom P o ince in Thailand, comp ises
six sub-dis ic s and spans an a ea o app oxima ely 520
km2 (Fig. 1A, B). I is one o wel e dis ic s ac oss h ee
p o inces loca ed in he lowe loodplain o he Songkh-
am Ri e Basin (Blake and Pi ak hepsombu 2006). The
Songkh am Ri e is a majo ibu a y o he Mekong Ri -
e ha lows h ough he no he n pa o no h-eas e n
Thailand. I o igina es in he Sakhon Nakhon P o ince
and lows eas wa ds h ough he Udon Thani, Sakhon
Nakhon and Bueng Kan P o inces be o e joining he Me-
kong Ri e a Ban Chai Bu i Ci y in he Nakhon Phanom
P o ince (Ho le and Sun o n a ana 2008).
Sampling and specimen p epa a ion
Fo y-eigh sampling si es ac oss six sub-dis ic s o he
Nawa Dis ic we e selec ed o copepod collec ion con-
duc ed be ween July and Augus 2023 (Fig. 1A, B). Sam-
ples we e collec ed quali a i ely using a hand ne and a
plank on ne wi h a 60 µm mesh size om a ious ypes
Figu e 1. Sampling si e and wo habi a s o Mongolodiap omus nakhonphanomensis sp. no .: A. Loca ion o he Nakhon Phanom
P o ince in he no h-eas e n Thailand (indica ed in yellow); B. Loca ion o he Nawa Dis ic wi hin he Nakhon Phanom P o ince
(indica ed in g een) and sampling si es (indica ed in ed spo s); C. I iga ion canal ( empo a y wa e body); D. Pe manen pond.
Zoosys . E ol. 101 (4) 2025, 1965–1983
zse.penso .ne
1967
o wa e bodies, including ice ields, oadside canals, i i-
ga ion canals, bu alo bogs, ponds and ese oi s (Fig. 1C,
D). Samples we e immedia ely ixed in app oxima ely 5%
o malin on spo . Wa e quali y pa ame e s, including pH,
empe a u e, conduc i i y and o al dissol ed solids (TDS),
we e measu ed a each sampling si e using a mul ip obe
de ice (Laqua Ho iba, WQ-310-K). Adul animals we e
picked ou and p ese ed wi h 70% e hanol in 1.5ml mi-
c o ubes in he labo a o y. Adul specimens we e dissec ed
unde an Olympus SZ51 s e eomic oscope in a mix u e o
glyce ol and 70% e hanol ( a io ~ 1:10 / ). Dissec ed spec-
imens we e moun ed in pu e glyce ol and sealed wi h ans-
pa en nail polish. Pe manen slides wi h dissec ed animals
we e examined wi h an Olympus compound mic oscope
(CX31) a 1000 imes magni ica ion. Pencil d awings we e
p oduced wi h a d awing ube (Olympus U-Da) moun ed
on a compound mic oscope. The d awings we e subse-
quen ly scanned and inalised using he g aphic so wa e
P oc ea e e sion 1.1. Specimens we e selec ed o scan-
ning elec on mic oscopy (SEM) and pho og aphed using a
LEO 1450 VP scanning elec on mic oscope, ollowing he
p o ocol o Wa i oy am and Sanoamuang (2017).
The mo phological e minology ollows Huys and
Boxshall (1991). Type specimens a e deposi ed a he
Thailand Na u al His o y Museum, Pa hum Thani, Thai-
land (THNHM) and he Nakhon Phanom Uni e si y,
Facul y o Science, Thailand (NPU).
Abb e ia ions
The ollowing abb e ia ions a e used h oughou he ex
and igu es: a, aes he asc; Enp, endopod; Exp, exopod;
Exp/Enp-n, exopodal segmen n/endopodal segmen n;
P1–P5, swimming legs 1–5; s, spine (s).
Associa ed auna
In o al, du ing he s udy, ou een species o Calanoida
and six species o Cyclopoida we e iden i ied (Table 1).
Amongs he species eco ded, Mongolodiap omus nak-
honphanomensis sp. no . is new o science and is desc ibed
he ein. The mos equen ly encoun e ed species we e Mon-
golodiap omus malaindosinensis, Eodiap omus d aconi-
signi omi, Mesocyclops a inis, and M. he mocyclopoides.
Taxonomic sec ion
O de Calanoida Sa s, 1903
Family Diap omidae Bai d, 1850
Genus Mongolodiap omus Kie e , 1937
Mongolodiap omus nakhonphanomensis sp. no .
h ps://zoobank.o g/D6BB71C2-3AF1-40F7-B965-D1493B296C0C
Figs 2–7
Type locali y. A pond in he Nong Hua Ngua Village
(Fig. 1D), Na Khun Yai Sub-dis ic , Na Wa Dis ic , Na-
khon Phanom P o ince, no h-eas e n Thailand; coo di-
na es: 17°30'01.47"N, 104°08'03.35"E, al i ude: 153 m
abo e sea le el.
Ma e ial examined. Holo ype: one adul male dis-
sec ed and moun ed on one slide (THNHM-IV-21117);
allo ype: one adul emale dissec ed and moun ed on one
slide (THNHM-IV-21118); pa a ypes: h ee adul males
and h ee adul emales dissec ed and moun ed on one
slide each (NPU 2025–01-04). All specimens collec -
ed om he ype locali y on 30 July 2023 by Piya hida
Monongde n.
E ymology. The speci ic name nakhonphanomensis
e e s o Nakhon Phanom P o ince in no h-eas e n Thai-
land, whe e he new species was disco e ed. The La in
su ix “-ensis” deno es o igin o place.
Desc ip ion. Adul male. Body leng h excluding cau-
dal se ae 2.1 mm (holo ype) (o he males: mean = 2.0,
n = 3) (Fig. 2A). Ros um (Fig. 1B) wi h wo spini o m
p ocesses. Pedige s 4 and 5 incomple ely used la e al-
ly (Fig. 1A). La e al wings (Fig. 2A) asymme ical: le
wing p olonged downwa ds, he igh wing expanded dis-
ally in la e al di ec ion; bo h ipped wi h hin spine. U o-
some (Fig. 2E) o ien a ed obliquely pos e iad owa ds
igh side. Geni al somi e sho , asymme ical, wi h small
Table 1. Copepod species eco ded om he s udy a ea.
Calanoid species Cyclopoid species
1. Den odiap omus ja anus (G ochmalicki, 1915) 1. Mesocyclops a inis Van de Velde, 1987
2. Eodiap omus d aconisigni omi B ehm, 1952 2. M. he mocyclopoides Ha ada, 1931
3. E. phuphanensis Sanoamuang, 2001 3. Mic ocyclops ubellus (Lilljebo g, 1901)
4. E. sanoamuangae Ranga Reddy & Dumon , 1998 4. The mocyclops c assus (Fische , 1853)
5. Heliodiap omus elegans Kie e , 1935 5. T. decipiens (Kie e , 1929)
6. Mongolodiap omus bo uli e (Kie e , 1974) 6. T. wol e ecki Kie e , 1938
7. M. dumon i Sanoamuang, 2001
8. M. malaindosinensis (Lai & Fe nando, 1978)
9. M. nakhonphanomensis sp. no .
10. M. pec inidac ylus (Shen & Tai, 1964)
11. Neodiap omus yang sekiangensis Mashiko, 195
12. Phyllodiap omus pa ach is ineae Sanoamuang & Wa i oy am, 2023
13. P. p aedic us Dumon & Ranga Reddy, 1994
14. Vie odiap omus blachei (B ehm, 1951)
zse.penso .ne
Wa i oy am, S. e al.: A new species o Mongolodiap omus Kie e , 1938 om no h-eas e n Thailand
1968
Figu e 2. Mongolodiap omus nakhonphanomensis sp. no ., adul male (holo ype): A. Habi us, do sal iew; B. Ros um; C, D. Righ
an ennule, segmen s 1–13 and 14–21, espec i ely; E. U osome, en ola e al iew.
se a on ou e dis al ma gin on igh side. U osomi es 2–3
each wi h long hai s on mid- en al su ace; o me so-
mi e longe han la e . U osomi e 4 wi h igh pos e o-
la e al ma gin dila ed; do sopos e io ma gin expanded,
o e lapping pa o ollowing somi e. Anal somi e sym-
me ical; anal ope culum small, wi h pos e io ma gin
sligh ly conca e. Caudal ami (Fig. 2A, E) symme ical;
each amus expanded dis ally, wi h se ules along bo h in-
ne and ou e ma gins; wi h six se ae (se ae II–VII): se ae
II–VI plumose, se a VII ba e. Righ amus wi hou chi in-
ous p ocesses o en al p ominences.
An ennules asymme ical, wi h he igh an ennule
ans o med and genicula ed, exhibi ing sexual dimo -
phism. Righ side an ennula (Fig. 2C, D) 22-segmen ed.
Se al o mula: 1+a (I), 3+a (II), 1+a (III), 1+a (IV), 1+a
(V), 1 (VI), 1+a (VII), 1+s (VIII), 2+a (VIX), 1+s (X), 1+s
(XI), 1+a+s (XII), 1+a+s (XIII), 2+a+s (XIV), 2+a+s (XV),
2+a+s (XVI), 2+s (XVII), 1+s (XVIII), 2+s (XIX), 3+s
(XX), 2 (XXI), 4+a (XXII). Segmen s 13 o 20 enla ged
and elonga ed; segmen s 18 and 19 genicula ed; segmen
20 (an epenul ima e) wi h comb-like p ocess ( ou ee h).
Le side an ennula (Fig. 4A) 25-segmen ed, eaching be-
Zoosys . E ol. 101 (4) 2025, 1965–1983
zse.penso .ne
1969
Figu e 3. Mongolodiap omus nakhonphanomensis sp. no .,
ligh mic oscope pho og aph o P5 male, pos e io iew.
yond he caudal se ae. Se al o mula as ollows: 1+a (I), 3+a
(II), 1+a (III), 1 (IV), 1+a (V), 1 (VI), 1+a (VII), 1+s (VIII),
2+a (IX), 1 (X), 1 (XI), 1+a+s (XII), 1 (XIII), 1+a (XIV), 1
(XV), 1+a (XVI), 1 (XVII), 1 (XVIII), 1+a (XIX), 1 (XX),
1 (XXI), 2 (XXII), 2 (XXIII), 2 (XXIV), 4+a (XXV).
An enna (Fig. 4B): coxa wi h one se a on inne side;
basis wi h wo se ae on inne dis al ma gin. Exp se -
en-segmen ed, wi h 1, 3, 1, 1, 1, 1, 1 se ae la e ally, h ee
se ae apically. Enp wo-segmen ed; Enp-1 wi h wo se ae
a 1/2 leng h, Enp-2 wi h nine se ae along inne ma gin
and se en se ae apically, accompanied by sho ow o
spinules on dis al ou e ma gin.
Mandible (Fig. 4C): coxa wi h i e bi-cuspida e ee h
and one blun oo h on gna hobase; wi h small do sal se a
on dis ola e al co ne . Basis wi h ou se ae along inne
ma gin. Enp wo-segmen ed; Enp-1 wi h ou se ae on
dis al inne co ne . Enp-2 wi h nine se ae apically, ac-
companied by ow o spinules along ou e ma gin. Exp
4-segmen ed, wi h 1, 1, 1, and 3 se ae, espec i ely.
Maxillule (Fig. 4D): p aecoxal a h i e wi h en obus
se ae apically and ou ine se ae on do sal side. Coxal en-
di e wi h h ee ine se ae; coxal epipodi e wi h eigh obus
se ae. Basis wi h wo endi es, each a med wi h ou se ae;
basal exi e wi h one small se a. Enp educed, ep esen ed
by eigh se ae apically. Exp wi h se en apical se ae.
Maxilla (Fig. 4E): p oximal and dis al p aecoxal en-
di es wi h ou and h ee se ae, espec i ely. Two coxal
endi es wi h h ee se ae each. Allobasis wi h h ee se ae on
basal endi e. Enp wo-segmen ed, each wi h h ee se ae.
Maxilliped (Fig. 4F): coxa wi h ou endi es, bea ing 1,
2, 3 and 4 se ae, espec i ely. Basis wi h h ee se ae dis-
ally plus ow o s ong spinules along inne ma gin. Enp
six-segmen ed, wi h 2, 3, 2, 2, 2 and 4 se ae, espec i ely.
P1–P4 (Fig. 5A–D). P1 wi h wo-segmen ed Enp and
h ee-segmen ed Exp; P2–P4 wi h h ee-segmen ed Enp
and Exp; Exp longe han Enp. Coxa on P1–P4 wi h pin-
na e se a a dis al inne co ne . P4 basis wi h small se a a
dis al ou e ma gin. Exp-1 P1–P4 wi h one obus spine
on ou e ma gin and pinna e se a on inne ma gin. Exp-2
as Exp-1, bu P1 wi hou spine on ou e ma gin. Exp-3
wi h h ee pinna e se ae on inne ma gin and h ee pin-
na e se ae apically on P2–P4, bu wo on P1 inne ma gin.
Enp-1 P1–P4 wi h one pinna e se a on inne ma gin. P1
Enp-2 wi h h ee se ae on inne ma gin, wo se ae apical-
ly, one pinna e se a on ou e ma gin. P2–P4 Enp-2 wi h
wo pinna e se ae on inne ma gin. Enp-3 P2–P4 wi h
h ee se ae on inne ma gin, wo se ae apically and wo
pinna e se ae on ou e ma gin.
P5 (Figs 3, 5E, F) asymme ical, wi h igh leg ma ked-
ly enla ged. In e coxal pla e wi h ounded dis al ma gin.
Righ side o P5: coxa wi h spini o m se a on pos e io
lobe, no eaching mid-leng h o basis. Basis app oxi-
ma ely wice as long as wide, wi h na ow hyaline lamel-
la along p oximal inne ma gin and hyaline p ominence
a mid-dis al egion; wi h small se a a 3/4 leng h o ou e
ma gin. Exp h ee-segmen ed: Exp-1 sho e han wide,
wi h unp oduced dis al ou e co ne and semici cula hya-
line p ominence dis ally. Exp-2 ellip ical, wi h dis al po -
ion b oade han p oximal one, abou 2.5 imes as long as
wide; wi h s ong blun spine a 1/2 leng h o ou e ma -
gin and blun p ocess dis ally. Spine cu ed backwa ds,
sligh ly sho e han hal segmen leng h. Exp-3 as sick-
le-shaped claw, abou 1.5 imes as long as Exp-2; wi h
inne ma gin se a ed. Enp 1-segmen ed, conical, g adu-
ally ape ing dis ally, eaching he mid-leng h o Exp-2;
wi h spinula ed ip. Le side o P5: coxa wi h hin se a
a dis al inne ma gin, eaching beyond mid-hal o ba-
sis. Basis wi h na ow hyaline lamella along dis al inne
ma gin; wi h sho , hin pos e ola e al se a on ou e ma -
gin. Exp h ee-segmen ed (Fig. 5E, F): Exp-1 longe han
wide, g adually ape ing in pos e io end; wi h a hai ield
a dis al hal o inne ma gin. Exp-2 o al, smalle han
Exp-1; wi h inne obus se a, accompanied by spinula
ield along inne ma gin. Exp-3 educed o a sho , ba e
segmen wi h ounded ip. Enp one-segmen ed, conical,
g adually ape ing dis ally; eaching end o Exp-1, wi h
spinula e ip.
Adul emale. Body leng h excluding caudal se ae
2.5 mm (allo ype) (o he emales: mean = 2.3, n = 3)
(Fig. 6A). An ennules symme ical, wi h se al o mula
iden ical o ha o he le an ennule o male. An enna
and mou h appendages as in male. Cephalosome and
pedige 1, as well as pedige s 4 and 5, comple ely used.
Pedige 5 (Figs 6A, 7B) wi h asymme ical pos e ola e al
wings: igh wing sho , ounded, wi h s ong la ge spine
do sally, iny spine on pos e io ma gin; le wing longe ,
sub iangula , wi h iny spine do sally, la ge spine pos e-
zse.penso .ne
Wa i oy am, S. e al.: A new species o Mongolodiap omus Kie e , 1938 om no h-eas e n Thailand
1970
Figu e 4. Mongolodiap omus nakhonphanomensis sp. no ., adul male (holo ype): A. Le an ennule; B. An enna; C. Mandible;
D. Maxillule; E. Maxilla; F. Maxilliped.
io ly. U osome (Fig. 7A) h ee-segmen ed; geni al dou-
ble-somi e longe han wo subsequen u osomi es and
caudal ami combined. Geni al double-somi e (Fig. 7A)
asymme ical; le side b oadly expanded la e ally a he
p oximal pa , wi h s ong spine; igh side wi h p oximal
pa sligh ly expanded la e ally. Bo h spines a icula ed,
inse ed on somi e p ominence. U osomi e 2 symme i-
cal, sho e han wide, pa ly co e ed by pos e io end o
geni al double-somi e. Anal somi e and caudal ami as in
male (Fig. 7A).
Zoosys . E ol. 101 (4) 2025, 1965–1983
zse.penso .ne
1971
Figu e 5. Mongolodiap omus nakhonphanomensis sp. no ., adul male (holo ype): A. P1; B. P2; C. P3; D. P4; E. P5, pos e io iew;
F. P5, on al iew.
zse.penso .ne
Wa i oy am, S. e al.: A new species o Mongolodiap omus Kie e , 1938 om no h-eas e n Thailand
1972
Figu e 6. Mongolodiap omus nakhonphanomensis sp. no ., line d awing and SEM pho og aphs o adul emale: A. Habi us, do sal
iew; B. P5, pos e io iew; C. P5, on al iew (1 = igh side o Exp-2, 2 = le side o Exp-2); D. Righ P5 Exp-2–3, pos e io iew.
P5 (Figs 6B, C, 7C, D) asymme ical. Coxa wi h a
s ou spine on a p ominence a he dis ola e al co ne in
do sal iew; coxal spine eaching p oximal ma gin o
Exp-1. Basis wi h hin se a a 1/2 leng h o ou e ma gin.
Exp h ee-segmen ed, Enp wo-segmen ed. Exp-1 ec -
angula , abou wice as long as wide. Exp-2 iangula :
igh side sho e and s ou e han le side (Fig. 6C1–2);
inne ma gin wi h ow o s ong spinules; wo longi udi-
nal idges en ally; dis al la e al se a s ongly modi ied
in o sho , s ou spine (Fig. 6D). Exp-3 educed o sho ,
s ou spine and long, hin se a. Enp cylind ical, ex end-
ing beyond hal -leng h o Exp-1. Enp-1 sho e han
Enp-2; Enp-2 wi h ci cula ow o spinules a na owed
apical end.
Va ia ions. In addi ion o body size di e ences, seg-
men 20 o he igh an ennule in males ha e a comb-like
p ocess wi h wo o i e ee h (Fig. 2D). The emale P5
Enp a ies in leng h, ex ending om he middle o he
dis al end o Exp-1. The size o he hyaline lamella on
he igh male P5 basis also a ies, appea ing in long and
na ow on he inne ma gin and ounded (Fig. 5E) in he
p oximal-dis al egion.
Zoosys . E ol. 101 (4) 2025, 1965–1983
zse.penso .ne
1973
Figu e 7. Mongolodiap omus nakhonphanomensis sp. no ., adul emale (allo ype): A. U osome, do sal iew; B. Pedige 5 and pa
o geni al double-somi e, do sal iew; C. P5, pos e io iew; D. P5, on al iew.
zse.penso .ne
Wa i oy am, S. e al.: A new species o Mongolodiap omus Kie e , 1938 om no h-eas e n Thailand
1980
Figu e 10. Dis ibu ion o he genus Mongolodiap omus Kie e , 1937: A. In sou heas Asia and China; B. In no h-eas e n Thailand.
Zoosys . E ol. 101 (4) 2025, 1965–1983
zse.penso .ne
1981
om an unspeci ied locali y in Thailand, bu i s p esence
has been con i med in oadside canal o he Sakon Nak-
hon P o ince, no h-eas e n Thailand (Ranga Reddy e al.
1998; Koompoo and Wa i oy am 2025); (10) M. nakhon-
phanomensis sp. no ., was ound om bo h empo a y and
pe manen wa e bodies in he Nakhon Phanom P o ince,
no h-eas e n Thailand ( he p esen s udy);
(11) M. mekongensis has been eco ded om a ious
ypes o wa e bodies wi hin he Mekong Ri e sys em
in no h-eas e n Thailand, Laos, Cambodia and sou he n
Vie nam (Boonmak and Sanoamuang 2022; Chaicha oen
and Sanoamuang 2022; Koompoo and Wa i oy am 2025).
In addi ion, i has been epo ed ou side he Mekong Ri e
sys em om Hainan Island in sou he n China (Wei e al.
2023); (12) M. pec inidac ylus was i s desc ibed om
he Hainan and la e eco ded om Guangdong, bo h in
sou he n China (Shen and Tai 1964; Li e al. 2018). This
species has been occasionally ound in a ious ypes o
wa e bodies in ou p o inces o no h-eas e n Thailand
(Sanoamuang 2002; Koompoo and Wa i oy am 2025)
and one p o ince o no he n Vie nam (T an e al. 2016).
Species in he Sundaland (Sunda ic) sub egion
(13) M. mephis opheles was p e iously misiden i ied in
Thailand and Malaysia, bu i is ac ually endemic o Ja a
(Indonesia) (B ehm 1933; Lai and Fe nando 1978, 1980;
Ranga Reddy e al. 1998).
Species in he Indo-Chinese and Wallacean
sub egions
(14) M. bi ulai was o iginally desc ibed om China and
has been epo ed om se e al locali ies unde he e-
co ded name o M. bi ulai and M. o mosanus, including
no he n (Hebei, Heilongjiang), eas e n (Fujian, Jiang-
su, Zhejiang), cen al and sou he n China (Guangdong,
Guangxi, Hainan, Hunan) (Li e al. 2018). I was la e
epo ed om Taiwan (Young e al. 2013), Vie nam (T an
e al. 2016) and he Philippines (Lopez e al. 2017); (15)
M. uenoi was i s desc ibed om Taiwan (Kikuchi 1936);
and subsequen ly epo ed om Wes Ja a and Wes Kali-
man an, Indonesia (Lai and Fe nando 1980; Ranga Reddy
e al. 2000; Aleksee e al. 2013, 2016), Kon Tum and Dak
Lak P o inces in cen al Vie nam (T an e al. 2016) and
Hainan Island in sou he n China (Li e al. 2018). How-
e e , due o incomple e mo phological desc ip ions, he
occu ence o his species in Indonesia emains unce ain
(Ranga Reddy e al. 2000). In no h-eas e n Thailand, i
was ound in bo h empo a y and pe manen wa e bodies
wi hin he Chi Ri e Basin, speci ically in Chaiyaphum,
Kalasin and Nong Bua Lam Phu P o inces (Ranga Reddy
e al. 2000). Howe e , M. uenoi was no obse ed in he
Songkh am, Mun and Mekong Ri e Basins du ing he
ecen ield su eys, whe e M. mekongensis was ound o
be dominan (Koompoo and Wa i oy am 2025).
Conclusion
A o al o 48 samples collec ed om Nawa Dis ic , Na-
khon Phanom P o ince, yielded i e o he ele en Mon-
golodiap omus species known om Thailand. One o
hem, M. nakhonphanomensis sp. no ., is desc ibed he e-
in. The new species is mos simila o M. pec inidac y-
lus, a membe o he M. mephis opheles (B ehm, 1933)
species g oup, as hey sha e unique cha ac e is ics, such
as he mo phology o he igh male P5 Exp-2 and he
absence o a chi inous p ominence on he igh caudal a-
mus in males. Howe e , hey can be easily dis inguished
by he p esence o absence o a ow o spinules on he
le P5 basis, he shape o he p incipal la e al spine on
he igh P5 Exp-2 in males, as well as he mo phology
o he la e al wings and P5 Exp-2 in emales. A p esen ,
al hough bo h species we e collec ed om he s udy a ea,
hey ha e ne e been ound oge he a he same locali-
y and he new species has been ound mo e equen ly
han M. pec inidac ylus. The dis ibu ion o species in he
s udy a ea, along wi h he biogeog aphic map gene a ed
om published li e a u e, sugges s ha he genus Mon-
golodiap omus has a ho spo in he Indo-Chinese sub e-
gion, pa icula ly in he Sou heas Asia.
Acknowledgemen s
This s udy was suppo ed by he Na ional Science, Re-
sea ch and Inno a ion Fund (NSRF) (Fundamen al Fund:
G an No. SRI-27/2023; P oposal No. 66A134000008).
We also hank he Edi o o he Wo ld Copepoda Da a-
base o p o iding aluable li e a u e.
Re e ences
Aleksee VR, Ha ne DG, Vaillan JJ, Yuso FM (2013) Cyclopoid and
calanoid copepod biodi e si y in Indonesia. Jou nal o Limnology
72(s2): 245–274. h ps://doi.o g/10.4081/jlimnol.2013.s2.e12
Aleksee VR, Yuso FM, Fe ilo a EB (2016) Con inen al copepod
biodi e si y in No h-Eas e n Bo neo, Malaysia. A h opoda Selec a
25(2): 183–197. h ps://doi.o g/10.15298/a hsel.25.2.05
Blake DJH, Pi ak hepsombu R (2006) Si ua ional analysis: lowe Songkh-
am Ri e Basin, Thailand. Mekong We lands Biodi e si y Conse a-
ion and Sus ainable Use P og amme, Bangkok, Thailand, 121 pp.
Boonmak P, Sanoamuang L (2022) Di e si y o eshwa e calanoid co-
pepods (C us acea: Copepoda: Calanoida) in Sou he n Vie nam wi h
an upda ed checklis o he coun y. Di e si y 14(7): e523. h ps://
doi.o g/10.3390/d14070523
B ehm V (1921) E gebnisse de Expedi ion Handel-Mazze i’s nach
China 1914 bis 1918, un e nommen au Kos en de Akademie de
Wissenscha en in Wien. Diagnosen neue En omos aken. I. Teil.
Anzeige de Akademie de Wissenscha en in Wien, Ma hema isch-
Na u wissenscha lichen Klasse 20(58): 194–196.
B ehm V (1933) Mi eilungen on de Wallacea-Expedi ion Wol e eck.
Mi eilung VII. Neue und wenig bekann e En omos aken. Zoolo-
gische Anzeige 104(5–6): 130–142.
zse.penso .ne
Wa i oy am, S. e al.: A new species o Mongolodiap omus Kie e , 1938 om no h-eas e n Thailand
1982
Chaicha oen C, Sanoamuang L (2022) Dis ibu ion and di e si y o
diap omid copepods in eshwa e habi a s o Cambodia (C us a-
cea: Copepoda: Calanoida: Diap omidae). Di e si y 14(11): e903.
h ps://doi.o g/10.3390/d14110903
Dussa B, De aye D (2002) Wo ld Di ec o y o Calanoida Copepoda o
Inland Wa e s. I. Calani o mes. Backhuys Publishe s, Leiden, 276 pp.
Gue ne J, Richa d J (1896) Diap omus blanci, Copépode nou eau e-
cueilli pa M. Edoua d Blanc à Boukha a (Tu kes an). Bulle in de la
Socié é zoologique de F ance 21: 53–56.
Ho le KG, Sun o n a ana U (2008) Socio-Economics o he Fishe ies o
he Lowe Songkh am Ri e Basin, No heas Thailand. MRC Tech-
nical Pape No. 17. Mekong Ri e Commission, Vien iane, 85 pp.
Huys R, Boxshall GA (1991) Copepod E olu ion. The Ray Socie y,
London, 468 pp.
Kie e F (1937) Süsswasse copepoden aus Os asien. II. Neue Diap o-
miden und Cyclopiden on de Insel Fo mosa. Zoologische Anzei-
ge 119: 58–64.
Kie e F (1938) F eilebende ude ussk ebse (C us acea, Copepoda)
on Fo mosa. Nihon Seibu su Chi i Gakkai Kaiho 8: 35–73.
Kie e F (1974) Eine neue Diap omidena aus Malaysia (C us acea,
Copepoda, Calanoida). Zoologische Anzeige 192(5/6): 420–424.
Kikuchi K (1936) A new species o Diap omus om Fo mosa. P oceed-
ings o he Impe ial Academy o Japan 12: 198–200. h ps://doi.
o g/10.2183/pjab1912.12.198
Koompoo K, Wa i oy am S (2025) F eshwa e copepods in he ib-
u a ies o he lowe Mekong Ri e Basin in Thailand. Biodi e si-
as (Su aka a) 26(4): 1846–1859. h ps://doi.o g/10.13057/biodi /
d260434
Lai HC, Fe nando CH (1978) Redesc ip ion o Neodiap omus bo uli e
Kie e and one o i s ela ed species (Calanoida, Copepoda). Hyd o-
biologia 59(3): 229–235. h ps://doi.o g/10.1007/BF00036502
Lai HC, Fe nando CH (1980) Zoogeog aphical dis ibu ion o Sou heas
Asian eshwa e Calanoida. Hyd obiologia 74: 53–66. h ps://doi.
o g/10.1007/BF00009015
Li H, Dumon HJ, Han BP, Lin Q (2018) Upda ed checklis and dis-
ibu ion o he diap omid copepods (Copepoda, Calanoida, Di-
ap omidae) o China. C us aceana 91(3): 335–352. h ps://doi.
o g/10.1163/15685403-00003752
Lopez MLD, Pascual JAF, Dela Paz ESP, Rizo EZC, To desillas DT,
Guin o SK, Han B, Dumon HJ, Mama il AC, Papa RDS (2017) An-
no a ed checklis and insula dis ibu ion o eshwa e mic oc us a-
ceans (Copepoda: Calanoida and Cyclopoida; Cladoce a: Anomop-
oda & C enopoda in he Philippines. The Ra les Bulle in o Zoology
65: 623–654.
Podshi alina VN, She ele a NG, Semeno a AS, Mi abdullaye IM
(2022) Eudiap omus ansyl anicus and E. ulga is (Copepoda:
Calanoida: Diap omidae): compa a i e mo phology, dis ibu ion
and ecology. Zoosys ema ica Rossica 31(1): 42–54. h ps://doi.
o g/10.31610/zs /2022.31.1.42
Ranga Reddy Y, Radhak ishna Y (1981) On he genus Heliodiap omus
Kie e in India, including he desc ip ion o a new species (Copepo-
da, Calanoida). Hyd obiologia 83: 161–172. h ps://doi.o g/10.1007/
BF02187159
Ranga Reddy Y, Sanoamuang L, Dumon HJ (1998) A no e on he Di-
ap omidae o Thailand, including edesc ip ion o h ee species and
desc ip ion o a new species (Copepoda, Calanoida). Hyd obiologia
361(1/3): 201–223. h ps://doi.o g/10.1023/A:1003135200559
Ranga Reddy Y, Sanoamuang L, Dumon HJ (2000) Amended de-
limi a ion o Mongolodiap omus agains Neodiap omus and
Allodiap omus and edesc ip ion o he li le known Mongolo-
diap omus uenoi (Kikuchi, 1936) om Thailand (Copepoda: Cala-
noida: Diap omidae). Hyd obiologia 418(1): 99–109. h ps://doi.
o g/10.1023/A:1003859908612
Rylo VM (1922) O no ykh idakh Copepoda-Calanoida. On new spe-
cies o Copepoda -Calanoida. T udy Lening adskogo Obshches o
Es es oispy a elei. O delenie Zoologii 52: 67–78.
Rylo VM (1930) P esno odnye Calanoida SSSR. Op edeli eli o ga-
nizmo p esnych od SSSR, 1. Ins i u a Rybnogo Khozyais i a i
P omyslo ykh Issledo aniy, Lening ad, 288 pp.
Sanoamuang L (2001) Mongolodiap omus dumon i n. sp., a new esh-
wa e copepod (Calanoida, Diap omidae) om Thailand. Hyd obi-
ologia 448(1/3): 41–52. h ps://doi.o g/10.1023/A:1017526018189
Sanoamuang L (2002) F eshwa e Zooplank on: Calanoid Copepods in
Thailand. Klangnana ham Publishe s, Khon Kaen, Thailand, 159 pp.
Sanoamuang L, Dabseepai P (2021) Di e si y, dis ibu ion, and hab-
i a occu ence o he diap omid copepods (C us acea: Copepoda:
Diap omidae) in eshwa e ecosys ems o Thailand. Wa e 13(17):
e2381. h ps://doi.o g/10.3390/w13172381
Sanoamuang L, Koompoo K (2024) A desc ip ion o a new species o
Mongolodiap omus Kie e , 1937 (Copepoda, Calanoida, Diap omi-
dae) om Thailand wi h an up- o-da e key o he genus. ZooKeys
1209: 19–42. h ps://doi.o g/10.3897/zookeys.1209.125838
Sanoamuang L, Wa i oy am S (2018) Mongolodiap omus mekongen-
sis, a new species o copepod (Copepoda, Calanoida, Diap omidae)
om empo a y wa e s in he loodplain o he lowe Mekong Ri e
Basin. The Ra les Bulle in o Zoology 66: 782–796.
Schmoke C, Mahjoub MS, Calbe A, Hsiao SH, Russo F, La sen O,
T o e A, D ille G (2014) A e iew o he zooplank on in Singapo e
wa e s. The Ra les Bulle in o Zoology 62: 726–749.
Shen CJ, Lee FS (1963) The es ua ine Copepoda o Chiekong and
Zaikong Ri e s, Kwan ung P o ince, China. Dong Wu Xue Bao
15(4): 571–596.
Shen CJ, Tai AY (1964) Desc ip ions o new species o eshwa e Co-
pepoda om Kwang ung P o ince, Sou h China. Dong Wu Fen Lei
Xue Bao 1(2): 367–396.
Shen CJ, Tai AY (1965) Desc ip ions o six new species o eshwa e
copepods chie ly om he Pea l Ri e del a, Sou h China. Dong Wu
Fen Lei Xue Bao 2: 126–140.
Shen CJ, Tai AY, Zhang ZC, Li ZY, Song DX, Song YC, Chen GX
(1979) Fauna Sinica. C us acea, F eshwa e Copepoda. Science
P ess, Beijing, 450 pp.
T an DL, Dang NT, Ho TH (2016) An anno a ed checklis o he amily Di-
ap omidae Sa s, 1903 (Copepoda, Calanoida) in Vie nam. Tap Chi Sinh
Hoc (38): 384–399. h ps://doi.o g/10.15625/0866-7160/ 38n3.8515
Umi WAD, Yuso FM, A is AZ, Sha ip Z, Sine AY (2020) Plank onic
mic oc us acean communi y s uc u e a ies wi h ophic s a us and
en i onmen al a iables in opical shallow lakes in Malaysia. Di-
e si y 12(9): e322. h ps://doi.o g/10.3390/d12090322
Wal e TC, Boxshall G (2025) Wo ld o Copepods Da abase. Mongolo-
diap omus Kie e , 1937. Wo ld Regis e o Ma ine Species. h ps://
www.ma inespecies.o g/aphia.php?p= axde ails&id=347524 [on
2025-05-05]
Wa i oy am S (2021) Ca e-Dwelling Copepods in Thailand. KKU
P in ing House, Khon Kean, 254 pp.
Zoosys . E ol. 101 (4) 2025, 1965–1983
zse.penso .ne
1983
Wa i oy am S, Sanoamuang L (2017) A new species o Mongolodiap o-
mus Kie e , 1938 om no heas Thailand and a key o he species
(C us acea: Copepoda, Calanoida, Diap omidae). ZooKeys 710:
15–32. h ps://doi.o g/10.3897/zookeys.710.13941
Wei C-J, Xiong D-N, Wang Y-L, Feng W-S, Miao R-L, Gong Y-C
(2023) Fi s eco d o Mongolodiap omus mekongensis in China and
i s phylogene ic analysis. Shui Sheng Sheng Wu Hsueh Bao 47(10):
1640–1648. h ps://doi.o g/10.7541/2023.2022.0309
Young SS, Shih CT (2011) F eshwa e calanoids (Copepoda, Cala-
noida) o Taiwan, wi h some commen s on he mo phology o
Neu odiap omus umidus Kie e , 1937 obse ed by SEM. In:
De aye D, Sua ez-Mo ales E, Vaupel Klein JC (Eds) S udies on
F eshwa e Copepoda: A Volume in Honou o Be na d Dussa .
C us aceana Monog aphs (Vol. 16). B ill, 545–566. h ps://doi.
o g/10.1163/9789004188280_024
Young SS, Lin SC, Liu MY (2013) Gene ic di e si y and popula ion
s uc u e o wo eshwa e copepods (Copepoda: Diap omidae),
Neodiap omus schmacke i (Poppe and Richa d, 1892) and Mon-
golodiap omus bi ulai (Rylo , 1922) om Taiwan. Di e si y 5(4):
796–810. h ps://doi.o g/10.3390/d5040796
