A new species of Pseudodiaptomus (Copepoda, Calanoida, Pseudodiaptomidae) from the Great Barrier Reef, Australia

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A new species o Pseudodiap omus (Copepoda, Calanoida,
Pseudodiap omidae) om he G ea Ba ie Ree , Aus alia
Julian U ibe-Palomino1, T. Chad Wal e 2
1 Commonweal hScien i icandIndus ialResea chO ganisa ion(CSIRO)En i onmen ,QueenslandBiosciencesP ecinc ,B isbane,Aus alia
2 Na ionalMuseumo Na u alHis o y,Smi hsonianIns i u ion,Washing on,DC,USA
Co espondingau ho :JulianU ibe-Palomino(julian.u ibepalomino@csi o.au)
Copy igh : ©
Julian U ibe-Palomino & T. Chad Wal e .
This is an open access a icle dis ibu ed unde
e ms o he C ea i e Commons A ibu ion
License (A ibu ion 4.0 In e na ional – CC BY 4.0).
Resea ch A icle
Abs ac
A new species o he deme sal calanoid copepod genus Pseudodiap omus is desc ibed
om specimens collec ed om he G ea Ba ie Ree , Aus alia. This species mos close-
ly esembles P. bu ckha d i in he s uc u e o male i h leg wi h educed endopods on
bo h legs, bu di e s om he la e in se e al ea u es, including a ma u es o male i h
leg, asymme ical emale u osome and pos e odo sal p ojec ions on he male p osome.
Key wo ds: Copepods, deme sal, endemic species, Sou h Paci ic Ocean
In oduc ion
Copepods a e highly di e se mic o-c us aceans and a e p obably he mos
abundan o he me azoans in aqua ic sys ems. Thei habi a s ange om
ee-li ing plank onic, meioben hic, deme sal and e en pa asi ic. The ee-li ing
copepods o he genus Pseudodiap omus He ick, 1884 cu en ly, consis s o
84 alid species (Wal e and Boxshall 2025). Membe s o his genus a e p ima -
ily deme sal and ypically ound in shallow coas al es ua ine-ma ine en i on-
men s, ex ending om eshwa e o hype saline wa e s, and eside nea o on
he bo om du ing he day and mig a e h oughou he wa e column om dusk
o dawn (Wal e 1984, 1986, 1987).
The mou hpa s and swimming legs a e e y simila among he species,
making hese body pa s o limi ed use o species de e mina ion e en hough,
i is known some a iabili y among he Pseudodiap omus species (Wal e
1986; S inui e al. 2013; Mulyadi 2022; Nishida e al. 2024). Howe e , he i h
pai o male swimming legs a e highly dimo phic and ha e high axonomic
alue, and occasionally in emales he p osome and u osome augmen a ions
a e species speci ic. The sepa a ion o species in his genus is acili a ed by
using species g oups and subg oups (Wal e 1986), which we e upda ed by
Wal e e al. (2002: 666).
F om he 84 accep ed species o Pseudodiap omus, i is known ha 16
species o hem inhabi coas al and su ounding wa e s om Aus alia,
which has a as e i o y in he Paci ic, he Indian, and he Sou he n Oceans
mainly, bu also includes ma i ime and insula e i o y in opical equa o ial
Academic edi o : Kai Ho s Geo ge
Recei ed:
12 Ma ch 2025
Accep ed:
16 Oc obe 2025
Published:
21 No embe 2025
ZooBank: h ps://zoobank.
o g/8CFAA4CB-A30B-475B-B74E-
21B25367E437
Ci a ion: U ibe-Palomino J,
Wal e TC (2025) A new species
o Pseudodiap omus (Copepoda,
Calanoida, Pseudodiap omidae) om
he G ea Ba ie Ree , Aus alia.
ZooKeys 1261: 69–81. h ps://doi.
o g/10.3897/zookeys.1261.152830
ZooKeys 1261: 69–81 (2025)
DOI: 10.3897/zookeys.1261.152830
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ZooKeys 1261: 69–81 (2025), DOI: 10.3897/zookeys.1261.152830
Julian U ibe-Palomino & T. Chad Wal e : Pseudodiap omus g eenwoodi sp. no . om he G ea Ba ie Ree
wa e s. Those species and hei p ima y loca ion a e men ioned as ollow:
P. annandalei Sewell (1919) [Queensland]; P. aus aliensis Wal e (1987)
[No he n Te i o y]; P. baylyi Wal e (1984) [No he n Te i o y, Queensland];
P. cle ei Sco A. (1909) [A u Island, Papua New Guinea, Aus alia]; P. cole axi
Bayly (1966) [Queensland, New Sou h Wales, Vic o ia]; P. co nu us Nicholls
(1944) [Vic o ia, Sou h Aus alia ]; P. galle i (Rose, 1957) [Wes e n Aus alia,
Sha k Bay]; P. g iggae Wal e (1987) [Papua New Guinea, A u A chipelago
and Queensland]; P. hickmani Sewell (1912) [New Sou h Wales, Cooks Ri e ];
P. hype salinus Wal e (1987) [Wes e n Aus alia, Sha k Bay], P. in lexus Wal-
e (1987) [Queensland]; P. me oni F üch l (1923) [A u Islands, Indonesia;
Queensland, Po Cu is]; P. occiden alus Wal e (1987) [Wes e n Aus alia];
P. o na us (Rose, 1957); P. paci icus Wal e (1986) [Queensland]; P. se icau-
da us (Sco T., 1894) [Queensland, He on Island].
The new species desc ibed in his pape is based on ma e ial ound in sam-
ples om he G ea Ba ie Ree ha we e dona ed by A.D. McKinnon and
M.S. Talbo du ing 1978–1980. These collec ions ha e been housed a he
Smi hsonian Ins i u ion, Na ional Museum o Na u al His o y (NMNH) o he
las 40 yea s and only ecen ly s udied and de e mined ha hey con ained
his new species.
Ma e ials and me hods
Specimens we e ixed and p ese ed in 10% neu alized o malin/seawa e
a e collec ion and hen we e ans e ed o 70% e hanol a he Smi hsonian
Ins i u ion, Uni ed S a es Na ional Museum (USNM). Male and emale speci-
mens we e s ained wi h chlo azol black and ans e ed o dep ession slides
in a solu ion o glyce ine–e hanol o de ailed examina ion unde a Wild s e-
eoscope. Habi us and dissec ed appendages we e examined and illus a ed
wi h he aid o a came a lucida a ached o a Nikon Op ipho DIC Phase Con-
as Compound Mic oscope. Digi aliza ion o he d awings was achie ed by
using Adobe Illus a o . 27.9.6. Z-s acking images o he habi us o a pai
o adul male and emale specimens and hei co esponding i h legs we e
ob ained using an Olympus DP80 digi al came a a ached o an au oma ed
up igh epi luo escence mic oscope Olympus BX63 wi h CellSens ope a ing
so wa e and a mo o ized Z-d i e om he USNM. Body measu emen s o
male and emale specimens we e made using a luo escence mic oscope
Olympus BX51 also a USNM.
All measu emen s we e done wi h a calib a ed ocula mic ome e and a e
p esen ed in millime es. P osome leng h was measu ed om i s mos an e io
ma gin o he pos e io ip o he p osome and u osome leng h was measu ed
om he an e io inse ion on p osome o he pos e io ip o caudal ami.
Body and appendage e minology ollows he e minology es ablished by
Huys and Boxshall (1991).
Sys ema ics
O de Calanoida Sa s, 1903
Family Pseudodiap omidae Sa s, 1902
Genus Pseudodiap omus He ick, 1884
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ZooKeys 1261: 69–81 (2025), DOI: 10.3897/zookeys.1261.152830
Julian U ibe-Palomino & T. Chad Wal e : Pseudodiap omus g eenwoodi sp. no . om he G ea Ba ie Ree
Pseudodiap omus g eenwoodi sp. no .
h ps://zoobank.o g/D8C6AF0B-75AE-4C68-B35F-6B102D077413
Figs 1–5
Type locali y. Aus alia, Queensland, G ea Ba ie Ree , Liza d Island, 14°40.45'S,
145°26.49'E, cap u ed using ligh aps o e co al ee .
Type specimens. Holo ype: ♂; USNM 1754446. Allo ype: ♀; USNM 1754447.
Pa a ypes: Aus alia • 10 ♀♀, • 10 ♂♂; G ea Ba ie Ree , Liza d Island;
Jan.1978; M.S. Talbo ; USNM 1754448; specimens in ac ; all ypes emo ed
om o iginal collec ion USNM 1110847.
Addi ional ma e ial. Aus alia • 2 ♂♂, 2 ♀♀; G ea Ba ie Ree ; Jul. 2000;
A.D. McKinnon; USNM 310675 • 3 ♀♀; Queensland, Haugh on Ri e Es ua y;
Sep 1992; A.D. McKinnon; USNM 310761 • 100+ specimens; Queensland, G ea
Ba ie Ree , co al ee , Liza d Island; Jan. 1977–Jan. 1978; M.S. Talbo ; USNM
1110845–1110847; cap u ed using ligh aps o e ee s.
Desc ip ion. Common ea u es sha ed by emales and males:
An ennule (Fig. 1A, B) o emales and le male an ennule possess-
ing 22 segmen s, segmen s 6 and 7 pa ly used and coun ed sepa a ely,
wi h modi ied ba bed se a on segmen 20.
Figu e 1. Pseudodiap omus g eenwoodi sp. no . A. Female an ennule; B. Male an ennule le ; C. Male an ennule igh .
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ZooKeys 1261: 69–81 (2025), DOI: 10.3897/zookeys.1261.152830
Julian U ibe-Palomino & T. Chad Wal e : Pseudodiap omus g eenwoodi sp. no . om he G ea Ba ie Ree
Se al elemen s: (segmen numbe = se ae + aes he asc [ae]) Female: 1 = 1 +
ae, 2 = 2 + ae, 3 = 1 + ae, 4 = 2 + ae, 5 = 2 + ae, 6–7 = 2 + ae, 8 = 2 + ae, 9 = 1 +
ae, 10 = 1 + ae, 11 = 1 + ae, 12 = 2 + ae, 13 = 1 + ae, 14 = 2 + ae, 15 = 2, 16 = 2,
17 = 2, 18 = 1, 19 = 2, 20 = 2 + ae, 21 = 2, 22 = 7. Male: 1 = 1 + ae, 2 = 1 + ae, 3 =
2 + ae, 4 = 1 + ae, 5 = 1 + ae, 6-7 = 2 + ae, 8 = 0 + ae, 9 = 1 + ae, 10 = 0 + ae, 11
= 1 + ae, 12 = 2 + ae, 13 = 2 + ae, 14 = 2 + ae, 15 = 2, 16 = 2, 17 = 1 + ae, 18 = 1,
19 = 1, 20 = 2 + ae, 21 = 2, 22 = 7.
Figu e 2. Pseudodiap omus g eenwoodi sp. no ., cephalic appendages. A. An enna; B. Mandible; C. Maxillule; D.
Maxilla; E. Maxilliped.
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ZooKeys 1261: 69–81 (2025), DOI: 10.3897/zookeys.1261.152830
Julian U ibe-Palomino & T. Chad Wal e : Pseudodiap omus g eenwoodi sp. no . om he G ea Ba ie Ree
Figu e 3. Pseudodiap omus g eenwoodi sp. no ., male. A. Habi us do sal iew; B. U osome enla ged iew; C. Caudal ami
do sal iew; D. Leg 5 pos e io iew; E. Leg 5 an e io iew.
An enna (Fig. 2A): coxa wi hou se a, basis and i s endopodal segmen
comple ely use wi h 1 se a each, endopodal segmen 2 wi h 8 and 8 se ae on
e minal and sub e minal lobes espec i ely; exopod 3-segmen ed, i s wi hou
se a, second wi h 1 p oximal, 2 medial and 1 e minal se ae; hi d wi h 3 medial
and 4 e minal se ae.

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ZooKeys 1261: 69–81 (2025), DOI: 10.3897/zookeys.1261.152830
Julian U ibe-Palomino & T. Chad Wal e : Pseudodiap omus g eenwoodi sp. no . om he G ea Ba ie Ree
Mandible (Fig. 2B): basis inne ma gin wi h 4 se ae; endopod 2-segmen ed,
i s wi h 4 se ae, second wi h 6 se ae; exopod 5-segmen ed, i s o i h seg-
men s wi h 1, 1, 1, 1, 3 se ae, espec i ely. Gna hobase wi h one long se a e
do sal se a and 3 cuspida e and 4 small, ounded ee h.
Maxillule (Fig. 2C): p aecoxal a h i e wi h 8 s ong se ae; coxa wi h 4 se ae
on endi e and 9 on epipodi e; basis wi h 4 and 5 se ae on p oximal and dis al
endi es espec i ely; basal exi e wi h 1 educed se a; endopod 3-segmen ed,
wi h 4, 2 and 6 se ae espec i ely; exopod wi h 8 se ae along ma gin.
Maxilla (Fig. 2D): p aecoxa, coxa and basis pa ially used and, exopodi e
qui e educed wi hou isible segmen a ion. P aecoxal endi es wi h 3 and 3
se ae espec i ely; coxal endi es wi h 2 se ae each; basal endi e wi h 2 se ae
and endopod wi h 7 se ae.
Maxilliped (Fig. 2E): p aecoxa and coxa comple ely used, endi es wi h 0, 2,
3, 4 se ae; basis wi h 3 se ae; endopod 6-segmen ed, wi h 1 se a on he i s
segmen , second and hi d segmen s bea ing 2 simple se ae and 2 special o-
bus mid-ma gin se a e se ae; 1 se a on ou h and i h segmen s and, 7 se ae
on six h segmen .
Legs 1–4 (no igu ed, as hey a e alike in shape and a ma u e o igu es pub-
lished by Wal e (1986), S inui e al. (2013), and Nishida e al. (2024)), symme -
ical and bi amous wi h 3-segmen ed ami; coxa and basis o bo h ami wi h
spinules on dis al co ne . Se a and spine o mula as ollows:
Male (Figs 3A–E, 5C, D).
Body leng h 1.11–1.12 mm (n = 5); p osome leng h 2.4 imes u osome. Ceph-
alosome and i s pedige ous somi e sepa a e and pedige ous somi es 4 and 5
used wi h dis ola e al acu e p ojec ions. U osome 5-segmen ed, symme ical,
segmen s 2–4 pos e odo sal ma gins wi h ows o acu e spinule ows ex ending
la e ally. Caudal ami symme ical, each amus wi h 1 la e al, 4 e minal and 1 do -
sal se ae. U osomi es and caudal ami wi h p opo ions 12:27:14:12:14:21 = 100.
Male igh an ennule (Fig. 1C) 21-segmen ed, segmen s 6 and 7 sepa a e,
genicula e a segmen 18-19. Se al elemen s: 1 = 1 + ae, 2 = 1, 3 = 1 + ae, 4 = 2
+ ae, 5 = 1, 6 = 2 + ae, 7–8 = 3 + ae, 9 = 1 + 2ae, 10 = 0 + ae, 11 = 0 + ae, 12 = 1
+ ae, 13 = 1 + ae, 14 = 2 + ae, 15 = 1 + ae, 16 = 2 + ae, 17 = 0, 18 = 1, 19 = 1 and
medial spini o m p ojec ion, 20 = 2 + ae, 21 = 7.
Leg 5 (Fig. 3D, E). Righ leg: basis quad a e, wi h la ge plumose pos e io -su -
ace se a, an e io -su ace sub-dis al ow o spinules, one small p oximomedial
knob-like p ocess and a small digi al medial endopod which is e minally poin ed
wi h sho sub e minal se a. Exopod 1 comp essed, wi h dis ola e al la ge spin-
i o m p ocess, medial ma gin wi h la ge inge -like p ocess e minally hi su e
wi h ine spinules and e minal se a ( isible in an e io iew). Exopod 2 elonga -
ed and cu ed wi h a la ge dis ola e al spine eaching o midleng h o exopod
3, medial ma gin wi h a g oo e lined wi h small spinules and a se a. Exopod 3
medially cu ed, ape ing dis ally, medial ma gin wi h ine spinules and wo p ox-
imal se ae. Le leg: basis o simila size and shape o igh leg basis wi h la ge
coxa basis exopod endopod
Leg 1 0-1 0-0 I-1; 0-1; II, 1, 3 0-1; 0-1; 1, 2, 3
Leg 2–3 0-1 0-0 I-1; I-1; II, 1, 5 0-1; 0-2; 2, 2, 4
Leg 4 0-1 1-0 I-1; I-1; II, 1, 5 0-1; 0-2; 2, 2, 3
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Julian U ibe-Palomino & T. Chad Wal e : Pseudodiap omus g eenwoodi sp. no . om he G ea Ba ie Ree
la e al se a a mid-leng h, an e io -su ace sub-dis al ow o spinules, and small
dis omedial endopod wi h e minal se a. Exopod 1 small quad a e wi h a la ge
dis ola e al spine. Exopod 2 o al wi h a e y la ge p oximola e al spine, a small
sub-la e al se a a mid-leng h, su ounded by ine spinules, e mina es in a pai
o sho s ou spines, he e minal spine la ge , and 3 medial se ae.
Figu e 4. Pseudodiap omus g eenwoodi sp. no ., emale. A. Habi us do sal iew; B. U osome enla ged iew; C. U osome
1–3 en al iew; D. Leg 5 pos e io iew.
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Julian U ibe-Palomino & T. Chad Wal e : Pseudodiap omus g eenwoodi sp. no . om he G ea Ba ie Ree
Figu e 5. Pseudodiap omus g eenwoodi sp. no ., emale. A. Habi us do sal iew; B. Leg 5 pos e io iew; male, C. Habi us
do sal iew; D. Leg 5 pos e io iew.
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Julian U ibe-Palomino & T. Chad Wal e : Pseudodiap omus g eenwoodi sp. no . om he G ea Ba ie Ree
Female (Figs 4A–D, 5A, B).
Body leng h, 1.33–1.39 mm (n = 5). P osome leng h 2.6 imes u osome.
Cephalosome and pedige ous somi e 1 sepa a e, pedige ous somi es 4 and
5 comple ely used wi h 2 symme ical dis ally di ec ed pos e ola e al spine-
like p ojec ions and lined wi h ine spinules on each side o u osome inse ion.
U osome 4-segmen ed, geni al double-somi e sligh ly asymme ical, swollen a
midleng h and en ally, da ke owa ds he swollen geni al ape u e wi h double
ow o p oximal spinules, dis ally he geni al ape u e is co e ed wi h a 3-lobed
ope culum, 2 la e al lobes hinne and expanded pos e io ly, and a medial lobe
iangula e ape ing dis ally co e ing pai ed gonopo es used in o a U-shaped
s uc u e. U osomi es 2 and 3 o simila size, lacking spinule ows on pos e o-
do sal ma gins; somi es 3 and 4 asymme ical, igh la e al ma gin educed p o-
ducing a cu a u e; somi e 3 le pos e ola e al ma gin wi h small spinule pa ch.
Caudal ami asymme ical, igh amus mediola e ally cu ed and sligh ly hin-
ne . Each amus wi h ypically 1 la e al, 4 e minal and a small do sal se ae. Me-
dial ma gins o each amus lined wi h ine se ules. U osomi es 1–4 and caudal
ami wi h p opo ions 34:12:12:13:29=100. The egg sac is single when p esen .
Leg 5 uni amous and sligh ly asymme ical; basis sligh ly swollen medially,
wi h a la ge plumose la e al se a on pos e io su ace. Exopods 3-segmen ed,
exopod 1 ec angula and 2 imes longe han basipod, wi h dis ola e al spine.
Exopod 2 dis omedial co ne p oduced and poin ed wi h se a ed hyaline p o-
cess, le one sligh ly la ge han he igh , and sho dis ola e al se a. Exopod
3 slende wi h se a e ma gins and a p oximomedial spine. Endopods lacking.
E ymology. The species is named in honou o D Jack G eenwood (Uni e si-
y o Queensland), an Aus alian copepod axonomis , who dona ed many Aus-
alian pseudodiap omid samples o e he yea s o he second au ho .
Dis ibu ion. This species is cu en ly known om he no h o he G ea Ba -
ie Ree up o coas al wa e s o Towns ille and su ounding a eas.
Discussion
Mo phological ea u es o Pseudodiap omus g eenwoodi sp. no . a e unique
among he Aus alian species wi h he emale’s possession o pai ed pos e io
p ojec ions on pedige ous segmen s 5, and he male leg 5 le and igh endopods
a e simple and much educed in size. Based on he male leg 5 mo phology, i is
easy o assign his species o he Bu ckha d i species g oup o Wal e (1986), as
he leg 5 igh and le endopods a e udimen a y, small and simple, and exopod 1
has a small medial humb shaped p ojec ion. The emale and le male an ennule
ha e 22 segmen s and he 20 h a ba bed se a, and emales ha e a single egg sac.
The o iginal desc ip ion o P. bu ckha d i Sewell, 1932 was based only on e-
males collec ed om he Nicoba and Andaman Islands, and la e Pillai (1980)
edesc ibed he species and p esen ed he male o he species om he same
locali y. His edesc ip ion did no epo he la e al spinule ow on he emale
u osomi e 3, hough he no ed ha he emale leg 5 exopodal segmen 1 dis o-
la e al co ne s wi h spinule pa ch. Pillai’s igu es we e e y small and no clea .
Pseudodiap omus bu ckha d i was edesc ibed again by Wal e (1986) om
samples collec ed om Palau Islands. Male pedige ous somi e wi h pai ed
do sal la e al p ojec ions (Fig. 6A), emale u osomi e 3 possesses a spinule
ow only on igh la e al ma gin and simple leg 5 and asymme ical caudal ami