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Species Di e si y 29: 327–335
The Fi s La al Desc ip ion o he Common Aesop Slippe
Lobs e Scylla ides haanii (Decapoda: Achela a: Scylla idae)
Kooichi Konishi1,3, Takashi Yanagimo o1, and Seinen Chow2
1 Fishe ies Resou ces Ins i u e, Japan Fishe ies Resea ch and Educa ion Agency, Yokohama, Kanagawa 236-8648, Japan
E-mail: [email protected] (KK)
2 Aquos Ins i u e, 3-2153-79 Mo ohachioji, Hachioji, Tokyo 193-0826, Japan
3 Co esponding au ho
(Recei ed 19 Ma ch 2024; Accep ed 26 Augus 2024)
A la e-s age phyllosoma, collec ed om he No h Paci ic Ocean, was iden i ied as Scylla ides haanii (De Haan, 1841)
by DNA analysis. A mo phological desc ip ion o he phyllosoma o his common Indo-Paci ic species is gi en o he i s
ime. La al cha ac e is ics o la e phyllosoma s ages a e compa ed wi h hose o p e iously desc ibed Scylla ides Gill, 1898
and ela ed gene a. A en a i e key o scylla id phyllosomas in he la e-s ages is also p o ided.
Key Wo ds: C us acea, Achela a, Scylla idae, phyllosoma la a, DNA ba coding.
In oduc ion
The genus Scylla ides Gill, 1898 in he sub amily A c-
idinae consis s o 14 species (Hol huis 1991; DecaNe
2023), and la al desc ip ions ha e been gi en in 7 species
(Table 1). I is no able ha he phyllosoma s ages o S. haa-
nii (De Haan, 1841) a e ye o be desc ibed in he emain-
ing 9 species o Scylla ides, despi e he wide dis ibu ion o
adul lobs e s in he Paci ic and Indian Oceans (Mo in and
MacDonald 1984; Hol huis 1991; Báez e al. 2022). A la e-
s age scylla id phyllosoma specimen, collec ed om he
wes e n No h Paci ic Ocean, was examined mo phological-
ly and iden i ied as S. haanii by DNA ba coding. We p es-
en a mo phological desc ip ion o he la al specimen and
compa e he la al cha ac e is ics o Scylla ides species wi h
hose o ela ed gene a.
Ma e ials and Me hods
In he esea ch c uise o spawning s ock o neon squid
Ommas ephes ba amii (Lesueu , 1821) in he No h Paci -
ic Ocean pe o med by R/V Kaiyo-Ma u, Fishe ies Agency
o Japan, a la ge scylla id phyllosoma was caugh using a
ing ne (2 m mou h opening, 526 µm mesh) on 30 Oc obe
2013 a 33°01′N, 156°59′E. The ne was owed on he su -
ace a a speed o 1.9 k du ing day ime (10:30–10:56 hou s).
This phyllosoma was ixed in 80% e hanol on boa d and
ans e ed o he Fishe ies Resou ces Ins i u e. A small is-
sue piece was dissec ed om a pe eiopod, washed well wi h
ap wa e , and homogenized, om which c ude DNA was
ex ac ed using a DNA ex ac ion ki (QuickGene DNA is-
sue ki , DT-S, KURABO). Ampli ica ion p o ocols o pa ial
mi ochond ial 16S DNA sequence and nucleo ide sequence
de e mina ion we e ollowed by Ueda e al. (2021). The
nucleo ide sequence de e mined was subjec ed o BLAST
(basic local alignmen sea ch ool) (Al shul e al. 1990) in
Na ional Cen e o Bio echnology In o ma ion o ind
iden ical o simila sequences. Nucleo ide sequence align-
men was pe o med using he Clus alW algo i hm imple-
men ed in MEGA 6 (Tamu a e al. 2013) ollowed by man-
ual edi ing. Calcula ion o K2P dis ance be ween sequences,
selec ing he bes - i model o nucleo ide subs i u ion, and
cons uc ion o a neighbo -joining phylogene ic ee was
pe o med using MEGA 6.
A e he molecula analyses, he appendages we e dis-
sec ed using ine insec pins. Obse a ions and d awings
we e made wi h he aid o a d awing ube a ached o an
Olympus BX51 mic oscope and an SZX10 s e eomic o-
scope. The measu emen s we e aken as ollows: o al leng h
(TL) om he an e io ma gin o he cephalic shield be-
ween he eyes o he pos e io ma gin o he elson, cephal-
ic shield leng h (CL) om he an e io o he pos e io ma -
gin o he cephalic shield, pleon leng h (PL) om he base o
pleon o he pos e io elsonal ma gin, cephalic shield wid h
(CW) and ho ax wid h (TW) measu ed a he wides pa
o he cephalic shield and ho ax, espec i ely. The ouche
specimen o he phyllosoma, KY13-5-102 in he se ial num-
be by Fishe ies Agency esea ch c uise, was deposi ed a
he Hokkaido Uni e si y Museum unde he ca alog num-
be ICHUM-8558.
Resul s
DNA analysis. The nucleo ide sequence de e mined
was 432 bp and a ailable in he public da abases h ough
he DNA Da a Bank o Japan unde he In e na ional
Nucleo ide Sequence Da abases (INSD) accession num-
Published online 10 Oc obe 2024
DOI: 10.12782/specdi .29.327
328 Kooichi Konishi e al.
be LC763119. Agains his sequence, he mos simila se-
quences e u ned by BLAST sea ch we e o Scylla ides haa-
nii (INSD accession numbe s JN701690, JN701691, and
MN817127), in which he K2P dis ances be ween he se-
quences anged 0.00%–1.17%. The phylogene ic ee (Fig. 1)
unambiguously de e mined his phyllosoma o be S. haanii.
La al desc ip ion o Scylla ides haanii, s age X. The
phyllosoma s age o he p esen specimen was de e mined
acco ding o Robe son’s (1969a) s age key o phyllosoma.
Dimensions: TL = 39.5 mm, CL = 28.8 mm, CW = 25.0 mm,
TW = 17.8 mm, PL = 6.4 mm.
Cephalo ho ax (Figs 2, 3A): ou line o cephalic shield el-
lipsoid, sligh ly wide han long (CL/CW a io = 1.15), and
much wide han ho ax (CW/TW a io = 1.40). Small o e -
hang pla e behind he base o eyes alk (Fig. 3B).
An ennule (Fig. 4A): peduncle 3-segmen ed, ou e la-
gellum longe han hal leng h o inne lagellum, wi h 5–6
ie s o aes he ascs on i s inne ma gin.
An enna (Fig. 4B): la ened do so en ally, 3-segmen ed,
he second segmen an e io ly poin ed.
Mandibles (Fig. 4C): sligh ly la ened do so en ally,
asymme ical in den i ion. Inciso p ocess and medial gna-
hal edge wi h a se ies o ee h. Mola p ocess c owned by
many den icules and minu e papillae. Dis al inne hal po -
ion o mandible co e ed wi h lab um and pa agna h.
Maxillule (Fig. 4D): no endopod p ojec ion. Basal endi e
wi h 3 s ou spines and 8 sub e minal se ae. Coxal endi e
wi h 12–13 s ou se ae.
Maxilla (Fig. 4E): endopodal a ea wi h 2 hin se ae. Basal
and coxal a ea wi h 2 and 1 hin an e io se ae, espec i ely.
Scaphogna hi e wi hou ma ginal plumose se ae.
Maxilliped 1 (Fig. 4F): 3-lobed p ocess, wi h a sho se a
on endopodal a ea.
Maxilliped 2 (Fig. 4G): endopod 5-segmen ed, penul i-
ma e segmen wi h 2 s ou spines and 12 se ae in o al. Exo-
pod udimen a y bud. No gill udimen s.
Maxilliped 3 (Fig. 4H): endopod 4-segmen ed, wi h many
se ae on dis al segmen . Exopod udimen a y bud. No gill
udimen s.
Pe eiopods 1–5 (Fig. 3A): exopods dis ally lagella ed
wi h annuli bea ing a pai o na a o y se ae. No gill udi-
men s on pe eiopods and ho ax pleu a.
Pleon (Fig. 3C): much na owe han ho ax, somi e seg-
men ed wi h bi amous udimen s o pleopods (Fig. 3D) on
somi es 2–5. U opod bi amous, pos e io ma gins o en-
dopod and exopod eaching ha o he elson. Telson o al
wi hou spines.
Discussion
O he 17 species in he sub amily A c idinae includ-
Table 1. P e ious la al desc ip ions in he genus Scylla ides.
Species Sou ce o ma e ials Collec ion locali y Desc ibed s ages Re e ences
S. aequinoc ialis L/P Flo ida, Bahama, Columbia I–XI 1
S. aequinoc ialisaP Gul o Mexico I–VI 2a
S. aequinoc ialis P Wes e n A lan ic IV 3
S. as o ibP Gul o Cali o nia I, III, IV, VII 4
S. as o i P Gul o Cali o nia La e phyllosoma s ages 5
S. as o i L Gul o Cali o nia I 6
S. as o i P Gul o Cali o nia ni 7
S. elisabe haecP O Du ban La e phyllosoma s ages 8
S. he klo sii P S . Helena Island ni 9
S. he klo sii P/L Gul o Guinea ns, I, III, V, VI, VIII, IX, ni 10
S. la us L Medi e anean I 11
S. la us P Medi e anean II 12
S. la us P Medi e anean I 13
S. nodi e PA lan ic La e phyllosoma s ages 1
S. squammosus P New Caledonia La e phyllosoma s ages, ni 14
S. squammosus L O Kagoshima I–VId15
S. squammosus P Wes e n Paci ic La e phyllosoma s ages 16
S. squammosus L New Caledonia I 17
S. squammosus P*Co al Sea VI–XII 18
S. squammosus P*O Ogasawa a Islands ni 19
S. squammosus P*No hwes Paci ic IX–XI 20
S. sp. P*No hwes Paci ic VII, IX 20
S. sp-B P*Cen al No h Paci ic IX–XI 20
S. sp-C P*eNo hwes Paci ic XII 20
Abb e ia ions: L, labo a o y- ea ed; ni, nis o; ns, naupliosoma; P, plank on collec ion o wild-caugh ; P*, iden i ied by DNA analyses.
a In hei pape , he igu e cap ions 4 and 5 a e placed e e sely; b as ‘phyllosoma X’; c as Species Z; d ins a numbe ; e DNA was analyzed bu species
could no be de e mined.
Re e ences: 1 Robe son (1969a); 2 Manzanilla-Dominguez and Gasca (2004); 3 San ana e al. (2007); 4 Johnson (1968); 5 Johnson (1970); 6 Johnson
and Knigh (1975); 7 Johnson (1975); 8 Be y (1974); 9 Chace (1966); 10 C osnie (1972); 11 San ucci (1925); 12 Fiedle and Spanie (1996); 13 To es
e al. (2013); 14 Michel (1968); 15 Saisho and Sone (1971); 16 Sekiguchi (1990); 17 Cou u es (2001); 18 Pale o e al. (2016); 19 Hidaka e al. (2022); 20
Chow e al. (2022a).
La al desc ip ion o Scylla ides haanii 329
ing Scylla ides, la al desc ip ion has been gi en o 9 spe-
cies in 2 gene a, ep esen ing 53% o he o al. Howe e , in
mos o hese mo phological desc ip ions o la ae, hei
pa en age was based on es ima ion be ween loca ions o
plank onic specimens and p esumed adul dis ibu ions.
Some imes his ac can be con o e sial o decapod la -
al s udies, conce ning plank on dynamics. Fo example,
Chow e al. (2006) commen ed ha long-li ed eleplanic
la ae such as phyllosoma may d i o dis an wa e s due o
he long plank onic pe iod, whe e hei adul o ms do no
exis . The accu a e speci ic iden i ica ion o phyllosomas by
mo e ce ain me hods, such as labo a o y- ea ing o DNA
ba coding, is essen ial o basic popula ion s udies and s ock
managemen . To da e, only ou cases ha e been known o
he accu a e pa en age de e mina ion in he a c idine spe-
cies; A c ides egalis Hol huis, 1963, S. aequinoc ialis (Lund,
1793), S. he klo sii (He klo s, 1851), and S. squammosus (H.
Milne Edwa ds, 1837) (Robe son 1969a; C osnie 1972;
Pale o e al. 2016; Chow e al. 2021). The p esen s udy is he
i h la al desc ip ion based on he accu a e pa en age in
he A c idinae.
Acco ding o Robe son’s (1969a) s age key o S. ae-
quinoc ialis, he p esen specimen is assigned o s age X in
pleon ex ension beyond le el o o igin o pe eiopod 5 and in
lack o gill buds on pe eiopods. Howe e , in he body size,
TL o S. haanii is abou 1.4 imes la ge han S. aequinoc ia-
lis in he s age X. This size is nea o Sims’ (1965) inal XII
s age, which was o iginally desc ibed as ‘Pa ibacus’ and
la e a gued assigna ion o Scylla ides (Robe son 1969b;
Sekiguchi 1988). In Robe son’s (1969a) phyllosoma speci-
mens, he ea ly- o mid-s ages we e ob ained by labo a o y-
ea ing while he la e-s ages we e collec ed om plank on.
The accu acy o species iden i ica ion in i s la e- o inal-
s ages may be deba able. As only one specimen was a ailable
in ou s udy, i is cu en ly unclea whe he he di e ence
in body size be ween S. aequinoc ialis and S. haanii is due o
speci ic cha ac e is ics o no .
In he p eceding la al wo ks, wo g oups ha e been
ecognized o he mid- o la e-s age phyllosomas o he
Scylla ides (Robe son 1969a; Sekiguchi 1986, 1988)—
he i s g oup: S. he klo sii, S. nodi e (S impson, 1866), S.
squammosus; and he second g oup: S. aequinoc ialis, S. as-
o i (Hol huis, 1963). The mo phology o he p esen s udy
shows he phyllosoma o S. haanii belongs o he second
g oup. In he A c idinae, h ee mo pho ypes a e ca ego ized
in he la e-s age phyllosomas as ollows:
Type 1: cephalic shield na ow o oid, and pos e io ma -
gin o ho ax conca e be ween pe eiopod 5 wi h se ose exo-
pod—A c ides Hol huis, 1960.
Type 2: cephalic shield ellipsoid, and pos e io ma gin o
ho ax conca e be ween pe eiopod 5 wi hou se ose exo-
pod—S. he klo sii, S. nodi e , S. squammosus.
Type 3: cephalic shield ellipsoid, and pos e io ma gin o
ho ax conca e be ween pe eiopod 5 wi h se ose exopod—S.
aequinoc ialis, S. as o i, S. elisabe hae (O mann, 1894), and
possibly S. haanii.
Type 2 and Type 3 also co espond o Sekiguchi’s (1988)
i s and second g oups o Scylla ides phyllosoma, espec-
i ely.
In he amily Scylla idae, he la e-s age phyllosomas o
he genus Pa ibacus Dana, 1852 in he sub amily Ibachinae
show a close esemblance o hose o Scylla ides (Phillips e
al. 1981; Pale o e al. 2014a; Chow e al. 2022b). In he Pa -
ibacus, howe e , he second an enna o mid- o la e-s age
phyllosomas a e unsegmen ed, whe eas hose o he A c idi-
nae possess segmen ed an ennae. Fu he mo e, he cephalic
shield ou line is sligh ly obo oid in Pa ibacus. E en in he
Pa ibacus phyllosomas, an ennal segmen a ion occu s in
he inal s age (o gill s age), sugges ing ha he disc epancy
obse ed can be a ibu ed o a ia ions in he de elopmen-
al a es among di e en axonomic g oups. Ou p esen e-
sul also con i ms a close esemblance o he la e-s age Pa -
ibacus phyllosomas o hose o Scylla ides.
To summa ize he p eceding a gumen s, Table 2 p o ides
a compa ison o he main cha ac e is ics o phyllosoma a
o nea he same de elopmen al s age wi h hose p e ious-
ly desc ibed in he A c idinae and Pa ibacus o he Ibaci-
nae. In his ins ance, ou objec i e is o make compa isons
be ween la al cha ac e is ics a he same de elopmen al
s age whe e e possible, gi en he signi ican mo phological
changes ha occu du ing phyllosoma de elopmen .
Bais e (1994) showed a close ela ionship be ween A c-
ides, Scylla ides and Pa ibacus, ypi ied by he phylloso-
mas. Chow and Yanagimo o (2021) and Chow e al. (2022a)
s a ed as a gene al ea u e o la e-s age phyllosoma la ae
Fig. 1. Neighbo -joining phylogene ic ee d awn based on
Kimu a-2-pa ame e dis ances o pa ial 16S sequences be ween
11 a c idine slippe lobs e species and he sculp u ed slippe lob-
s e [Pa ibacus an a c icus (Lund, 1793) and P. japonicus Hol huis,
1960] as ou g oup species. Accession numbe s a e shown in pa-
en heses. Boo s ap alues o > 50% (ou o 1000 eplica es) a e
shown a he nodes. The same ee opology was ob ained by maxi-
mum likelihood and maximum pa simony me hods.
330 Kooichi Konishi e al.
Fig. 2. Scylla ides haanii (De Haan, 1841), s age X phyllosoma (ICHUM-8558). Whole body in do sal iew. Scale ba = 10 mm.
Fig. 3. Scylla ides haanii (De Haan, 1841), s age X phyllosoma (ICHUM-8558). A, Whole body in en al iew; B, an e io pa o cepha-
lon in do sal iew; C, pleon in do sal iew; D, igh pleopod 5.
La al desc ip ion o Scylla ides haanii 331
ha he dep ession be ween he base o pe eiopod 4 is pos-
e io o he ho ax in a c idine phyllosomas, whe eas i is
he base o pe eiopod 5 in hose o he ibachine genus Pa -
ibacus. Howe e , hei diagnos ic la al cha ac e is ics a e
no a key o comple ely dis inguishing hese wo gene a,
as he e a e wo la al mo pho ypes in Scylla ides phyllo-
somas. Al hough Pa ibacus phyllosomas in he la e s ages
esemble Type 3 lis ed abo e, hese a e dis inguished by he
an enna wi h no o ewe segmen s han hose o Scylla ides.
Addi ionally, he Pa ibacus phyllosomas each he la ges
body size in he Achela a; TL o he inal s age phyllosoma
anging 70–80 mm, which is la ge han 1.6 imes hose o
a c idine phyllosomas. The p esen esul econ i ms Scylla-
ides phyllosomas consis o a leas wo mo pho ype g oups
in he pos e io ho acic ma ginal dep ession be ween pe-
eiopods and exopods o pe eiopod 5.
Phillips e al. (1981) sugges ed ha hei ‘Scylla ides sp. a’
was simila o he inal s age phyllosoma o S. squammosus
known a ha ime. Sekiguchi (1990) no ed ha ‘Scylla ides
sp. a’ was dis inguished om S. squammosus and possibly
he inal s age o S. haanii. The inal s age o S. squammo-
sus by Pale o e al. (2016) also well co esponds wi h ‘Scyl-
la ides sp. a’ in he an enna, he dac ylus on pe eiopods, and
he mid-do sal pos e io spine on he pleonal somi es 2–5.
Ou p esen esul on S. haanii suppo s ha he ‘Scylla ides
sp. a’ is he inal phyllosoma o S. squammosus. The dac y-
lus leng h o he pe eiopod, i.e., sho hook-shaped o long
sickle-shaped, may also be complemen a y cha ac e is ic.
Fig. 4. Scylla ides haanii (De Haan, 1841), s age X phyllosoma (ICHUM-8558). A, An ennule; B, an enna; C, le mandible in en al iew;
D, maxillule (le ); E, maxilla ( igh ); F, maxilliped 2; G, maxilliped 3 showing udimen a y exopod (a ow).
332 Kooichi Konishi e al.
Howe e , as is well known, his agile pa is almos lacking
in he ield-collec ed specimens.
Th ee uniden i ied phyllosomas, ‘S. sp.’, ‘S. sp-B’, and ‘S.
sp-C’ by Chow e al. (2022a) belong o Type 2 in his s udy.
Johnson (1971) a ibu ed a se ies o mid-la e phylloso-
mas collec ed in he Hawaiian wa e s o S. squammosus.
Al hough S. squammosus and S. haanii coexis in his a ea
(Hol huis 1991), hese phyllosomas a e clea ly dis inguished
by mo pho ype, i.e., Types 2 and 3, and Johnson’s (1971)
speci ic iden i ica ion is now con i med. In addi ion, he
gian scylla id phyllosoma epo ed by Kishinouye (1918)
om he s omach con en s o he yellow in una, 45 mm
in body leng h, is he inal s age o Scylla ides phyllosoma
which belongs o Type 2. The uniden i ied gian scylla id
phyllosoma specimens desc ibed by Sims (1964) as ‘Phyl-
losoma A–D’ om he Flo ida S ai s appea s o belong o
la e- and inal-s ages o Scylla ides, based on he cha ac e is-
ics as ollows: 1) cephalic shield sligh ly wide han he ho-
ax (A–D), 2) pos e io ma gin o ho ax conca e be ween
pe eiopod 5 (A–D), 3) pe eiopods wi hou subexopodal
spines (A–D), 4) sho dac ylus on pe eiopod 5 (B and C),
and 5) pe eiopod 5 wi h se ose exopod (A, B, and D).
In he adul classi ica ion o he Scylla idae, close a in-
i y among h ee Scylla ides species, S. haanii, S. la us, and S.
squammosus was con i med by DNA analyses (Liu and Wang
2020). Wi hin hese h ee species, ou esul shows ha he
phyllosoma mo phology o S. haanii di e s om he emain-
de a leas in he la e s ages. Ne e heless, he eliabili y o
he pa en age wi hin he A c idinae emains signi ican ly in-
comple e no only in la al mo phology bu also in he con-
ex o DNA phylogene ic analyses e en in Scylla ides. The
disc epancy be ween he esul s o la al mo pho ypes and
hose o adul g oups based on gene ic analyses and/o labo-
a o y ea ing should be add essed wi h u he da a.
The CW/TW a io may be use ul o species disc imi-
na ion om mid o la e s ages in some cases (Chow e al.
2022a, b), bu his mo phome ic cha ac e is ic is no nec-
essa ily uni e sal o all de elopmen al s ages because hey
can change om he la e o he inal s age as ound in he
case o Pa ibacus japonicus Hol huis, 1960 (Table 2).
In addi ion, Robe son (1969b) compa ed he dac ylus
leng hs o pe eiopods and showed ha he dac ylus o he
Table 2. Compa ison o selec ed la al cha ac e is ics in la e-s age phyllosomas be ween a c idine and Pa ibacus species.
Species S age Ou line o
cephalic shield
TL
(mm)
CL
(mm)
CL/CW
a io
CW/TW
a io
An enna
segmen
Exopod
on P5
Pos e io conca e
ma gin o ho ax Re e ences
Sub amily A c idinae
Genus A c ides
A. guineensis X O oid, na ow 29.0 25.2a1.81a0.81a5+Be ween P5 21
A. egalis VIII O oid, na ow 29.5 24.8a1.82a0.79a2+Be ween P5 22
A. egalis VIII O oid, na ow 21.1 17.3 1.73 0.88 2 +Be ween P5 23
Genus Scylla ides
S. he klo sii IXbEllipsoid 19.8 16.0a1.42a1.23a3−Be ween P4 10
S. squammosus X Ellipsoid 33.4 26.3a1.37a1.18a(5) −Be ween P4 22
S. squammosus X Ellipsoid 31.0 24.0 1.30 1.07a5−Be ween P4 18
S. squammosus X Ellipsoid 27.1–31.1 20.2–24.4 1.37–1.41 1.12–1.22 3a−Be ween P4 20
S. squammosus XI Ellipsoid 36.6–40.0 28.5–30.2 1.32–1.38 1.19–1.23 3a−Be ween P4 20
S. squammosus XII ( inal) Ellipsoid 47.0–51.0 43.5a1.31a1.13a5−Be ween P4 18
S. squammosus XII ( inal) Ellipsoid 47.0 45.2 1.75 1.24a3 Be ween P4 16
S. nodi e XcEllipsoid 26.6 22.9a1.43a1.21a5−Be ween P4 6
S. sp. VII Ellipsoid 23.6 18.9 1.39 1.18 3 −Be ween P4 20
S. sp-B X Ellipsoid 27.3 21.8 1.35 1.26 5a−Be ween P4 20
S. sp-C XII Ellipsoid 48.9 34.0 1.30 1.20 5a−Be ween P4 20
S. aequinoc ialis X Obo oid, wide 28.8 21.2a1.30a1.30a5+Be ween P5 13
S. as o i IXbObo oid, wide 23.4 17.4a1.28a1.28a4a+Be ween P5 6
S. elisabe hae Xb,d Obo oid, wide 22.6a17.5a1.31a1.25a4a+Be ween P5 8
S. haanii X Ellipsoid 39.5 28.8 1.15 1.40 3 +Be ween P5 This s udy
Sub amily Ibacinae
Genus Pa ibacus
P. an a c icus IX Ellipsoid, wide 33.3–34.0 27.6e1.21e1.24e1+Be ween P5 24
P. an a c icus IX Ellipsoid, wide 32.4 26.8 1.29 1.22 1 +Be ween P5 25
P. an a c icus X Ellipsoid, wide 41.8 32.5a1.16a1.27a1+Be ween P5 22
P. an a c icus X Ellipsoid, wide 50.7 39.8 1.19 1.23 1 +Be ween P5 25
P. an a c icus XII ( inal) Obo oid, wide 77.0–80.0 55.8a1.12a1.33a1+Be ween P5 26
P. japonicus XI Obo oid, wide 70.9 52.8 1.03 1.44 1 +Be ween P5 25
P. japonicus XI Obo oid, wide 60.8 47.5 1.07 1.43 1 +Be ween P5 27
P. japonicus (Sub inal) Obo oid, wide 73.0 55.4 1.08 1.45a(2) +Be ween P5 27
P. japonicus XII ( inal) Obo oid, wide 80.0 57.0 1.19 1.24a2+Be ween P5 27
Abb e ia ions: CL, cephalic shield leng h; CW, cephalic shield wid h; P, pe eiopod; , udimen ; TL, o al leng h; TW, ho ax wid h; “+” means p esen ; “−” means absen .
a Calcula ed o judging om he o iginal ex igu es; b applying Robe son’s (1969a) s age key; c co esponding o Sim’s (1965) s age de ini ion; d as Species Z; e based on
he maximum alue in hei Table 2.
Re e ences (con inued om Table 1): 21 Robe son (1969b); 22 Johnson (1971); 23 Chow e al. (2021); 24 Pale o e al. (2014b); 25 Chow e al. (2022b); 26 P asad e al. (1975);
27 Yoneyama and Takeda (1998).
La al desc ip ion o Scylla ides haanii 333
pe eiopod 4 is la ge in Pa ibacus phyllosoma han in hose
o he A c idinae. Phyllosoma specimens om plank onic
collec ions, bu no only o he Scylla idae, a e agile and
usually ha e many missing pa s, especially he dis al pa o
he endopod in pe eiopods. Thus, all diagnos ic cha ac e is-
ics o phyllosomas a e comple ely a ailable in a e cases. I
is, he e o e, essen ial o keep his p ac ical ma e in mind
when selec ing mo phological cha ac e is ics o he classi i-
ca ion o iden i ica ion o phyllosoma la ae.
In conclusion, wi h e e ence o Sekiguchi’s (1986) key,
we en a i ely p esen an upda ed key o scylla id phylloso-
mas om he la e o inal s ages as below.
Key o Scylla id Phyllosmas
om he La e o Final S ages
1. Maxilliped 3 wi h se ose exopod
Palinu idae (S iden es)1
— Maxilliped 3 wi hou se ose exopod 2
2. An enna cylind ical, longe han an ennule
Palinu idae (Silen es)2
— An enna do so en ally comp essed, sho e han an en-
nule 3 (Scylla idae)
3. Cephalic shield bilobed eni o m wi h do sal ca inae and
spines Ibacus Leach, 1815
— Cephalic shield ounded ellipsoid, wi hou do sal o na-
men s 4
4. Pleon wid h mo e han hal o ho ax 5
— Pleon wid h less han hal o ho ax 6
5. Cephalic shield ci cula o wide han long; elson wi h
pos e ola e al spines Scylla inae
— Cephalic shield bilobed; elson wi hou pos e ola e al
spines Theninae
6. Pe eiopod wi h subexopodal spine
E ibacus Smi h, 1869
— Pe eiopod wi hou subexopodal spine 7
7. Cephalic shield na owe han ho ax
A c ides Hol huis, 1960
— Cephalic shield sligh ly o no ably wide han ho ax 8
8. Pe eiopod 5 wi hou se ose exopod
Scylla ides Gill, 1898 (in pa )3
— Pe eiopod 5 wi h se ose exopod 9
9. An enna unsegmen ed o wo-segmen ed; dac ylus o
pe eiopod 4 long Pa ibacus Dana, 1852
— An enna mo e han h ee-segmen ed; dac ylus o pe eio-
pod 4 sho Scylla ides (in pa )4
1 Panuli us Whi e, 1847, Palinu us Webe , 1795, Jus i ia
Hol huis, 1946, Linupa us Whi e, 1847, e c.; 2 Jasus Pa ke ,
1883, Sagma iasus Hol huis, 1991; 3 S. he klo sii (He klo s,
1851), S. nodi e (S impson, 1866), S. squammosus (H. Milne
Edwa ds, 1837); 4 S. aequinoc ialis (Lund, 1793), S. as o i
(Hol huis, 1963), S. elisabe hae (O mann, 1894), S. haanii
(De Haan, 1841).
Acknowledgmen s
Ou co dial hanks o he cap ain and c ews o R/V Kai-
yo-Ma u, Fishe ies Agency o Japan, o hei in aluable
suppo in he esea ch c uise. We a e g a e ul o D . M.
Sakai o p o iding us wi h aluable da a on he esea ch
c uise. Ou hanks a e also due o he anonymous e iew-
e s o hei aluable sugges ions and commen s. We also
dedica e his pape o he la e D . Hideo Sekiguchi, P o es-
so Eme i us o Mie Uni e si y, who passed away in Janua y
2023.
Au ho s Con ibu ions
Kooichi Konishi: Concep ualiza ion; Resou ces; Visu-
aliza ion; Supe ision; W i ing – o iginal d a . Takashi
Yanagimo o: In es iga ion; W i ing – e iew & edi ing. Sein-
en Chow: Funding acquisi ion; In es iga ion; W i ing – e-
iew & edi ing.
Funding
This s udy was pa ially suppo ed by he p ojec on he
E alua ion o he S a us o In e na ional Fishe y Resou ces
by he Fishe ies Agency o Japan.
Decla a ions
Compe ing in e es s. The au ho s decla e no con lic s
o in e es .
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