In e eb a e Zoology, 2025, 22(1): 21–29 © INVERTEBRATE ZOOLOGY, 2025
Myoana omy and ne ous sys em o a swimming- ype
la a Ba en sia g acilis (En op oc a: Coloniales)
A.O. Bo isano a
Facul y o Biology, Lomonoso Moscow S a e Uni e si y, Leninskie Go y 1-12, Moscow 119991 Russia.
Anas asia Bo isano a: [email p o ec ed] ORCID h ps://o cid.o g/0000-0002-9700-6446
ABSTRACT: The o ganiza ion o he muscula u e and ne ous sys em o he la ae o
En op oc a is s ill poo ly in es iga ed. Only a ew species ha e been s udied using me hods
o immunocy ochemis y and con ocal mic oscopy. P e iously in es iga ed la ae belong
o c eeping- ype la ae o swimming- ype la ae wi h a comple ely educed oo . This
s udy desc ibes he myoana omy and ne ous sys em (α- ubulin labeling) o he la a o
Ba en sia g acilis, he swimming- ype la a wi h a pa ially educed oo . The muscula u e
o B. g acilis includes he muscles o he apical o gan, a ious longi udinal and ans e se
muscles o he episphe e, he muscula u e o he oo udimen , he ing and longi udinal
muscles o he p o o och, and he muscula u e o he hyposphe e. The ne ous sys em
includes he apical and on al ganglia connec ed by apico- on al connec i es, pai ed oo
knob ne es, oo ne es and on al ne es, se e al ine ans e se ne es o he episphe e,
and he ne e ing o he p o o och.
How o ci e his a icle: Bo isano a A.O. 2025. Myoana omy and ne ous sys em o a
swimming- ype la a Ba en sia g acilis (En op oc a: Coloniales) // In e . Zool. Vol.22.
No.1. P.21–29. doi: 10.15298/in e zool.22.1.02
KEY WORDS: Kamp ozoa, ochopho e- ype la ae, immunocy ochemis y, α- ubulin,
phalloidin, con ocal lase -scanning mic oscopy.
Организация мускулатуры и нервной системы
планктонной личинки Ba en sia g acilis
(En op oc a: Coloniales)
А.О. Борисанова
Биологический факультет Московского государственного университета имени М.В.
Ломоносова, Ленинские горы 1-12, Москва, 119991, Россия. E-mail: [email p o ec ed]
РЕЗЮМЕ: Организация мускулатуры и нервной системы личинок En op oc a до сих пор
остается малоизученной. Методами иммуноцитохимии и конфокальной микроскопии
исследовано лишь несколько видов. Ранее изученные личинки относятся к ползающим
личинкам или планктонным личинкам с полностью редуцированной ногой. В данной
работе описана организация мускулатуры и нервной системы (окрашивание антителами
к α-тубулину) планктонной личинки Ba en sia g acilis с частично редуцированной
ногой. Мускулатура B. g acilis включает мышцы апикального органа, различные
продольные и поперечные мышцы эписферы, мускулатуру рудимента ноги, кольцевые
и продольные мышцы прототроха, а также мускулатуру гипосферы. Нервная система
включает апикальный и фронтальный ганглии, соединенные апико-фронтальными
De o ed o memo y o Claus Nielsen.
A.O. Bo isano a22
In oduc ion
En op oc s ha e a pelago-ben hic li e cycle
wi h a ben hic adul s age and a ochopho e-
ype la a (I ano a-Kazas, 1986). The la al
body consis s o an episphe e and a hyposphe e,
sepa a ed by a p o o och; he apical o gan is
loca ed a he apex o he episphe e. Two ypes
o la ae a e dis inguished: c eeping- ype la ae
and swimming- ype la ae (Wanninge , 2015).
C eeping- ype la ae ha e a well-de eloped
sensi i e on al o gan a he an e io edge o
he episphe e and a cilia ed oo on he en al
side o he hyposphe e. In swimming- ype la -
ae, he on al o gan and oo a e pa ially o
comple ely educed.
The ana omy o en op oc la ae emains
poo ly s udied. Some de ails o he s uc u e o
he ne ous and muscula sys em o la al s ages
ha e been desc ibed using elec on mic oscopy
me hods (Sensenbaugh, 1987; Haszp una , Wan-
ninge , 2008; Bo isano a, I ano a, 2024), bu
wi hou econs uc ing he o al ana omy o
hese o gan sys ems. Only a ew species ha e
been s udied using luo escence labeling and
con ocal scanning lase mic oscopy. The o ga-
niza ion o he muscula u e was s udied in he
c eeping- ype la a o Loxosomella mu manica
(Nilus, 1909) (Me kel e al., 2015) and in wo
species o he swimming- ype la ae wi h a
comple ely educed oo — Ba en sia disc e a
(Busk, 1886) (Bo isano a e al., 2012) and
Loxosomella a kinsae Bobin e P enan , 1953
(Fuchs, Wanninge , 2008). The o ganiza ion o
he se o one gic ne ous sys em was s udied
only in he c eeping- ype la a o L. mu manica
(Wanninge e al., 2007) and he swimming- ype
la a o L. a kinsae (Fuchs, Wanninge , 2008).
The p esen s udy was aimed a in es iga ion
o he o ganiza ion o he ne ous and muscula
sys ems o he swimming- ype la a o Ba en sia
g acilis (Sa s, 1835) wi h a pa ially educed oo
and a pa ially educed on al o gan.
Ma e ial and me hods
Ma e ial was collec ed in he Velikaja Salma Bay
(“G ea Salma s ai ”), Kandalaksha Bay, Whi e Sea
(66°34ʹ N, 33°08ʹ E) in Augus 2023. Specimens o
Ba en sia g aiclis wi h la ae in a ial ca i y we e
ixed in 4% PFA in 0.1 M PBS o e nigh a 4 °C, hen
washed six imes o 20 min in he 0.1 M PBS. Fo
α- ubulin labeling, he ma e ial was i s p eincuba ed
in 0.1 M PBS wi h 0.03% NaN3 and 5% T i on X-100
du ing one day a 4 °C, and hen incuba ed in 1%
Bo ine Se um Albumin (BSA) in 0.1 M PBS wi h
0.03% NaN3 and 1% T i on X-100 du ing nine hou s
a 4 °C o block unspeci ic binding si es. Incuba ion
in he i s an ibodies was ca ied ou using a mix u e
o mouse an i- y osina ed α- ubulin and mouse an i-
ace yla ed α- ubulin an ibodies in 0.01 M PBS wi h
0.03% NaN3, 1% T i on X-100 and 1% BSA du ing 18
h a 4 °C. A e six washes in 0.1 M PBS wi h 0.03%
NaN3 and 5% T i on X-100 he seconda y an ibodies
(an i-mouse donkey) was applied o 16 h a 4 °C.
Then he ma e ial was washed up six imes in he
0.1 M PBS. Fo phalloidin labeling, he ma e ial was
s ained wi h Alexa Fluo 488 phalloidin in 0.1 M PBS
wi h 0.03% NaN3 and 5% T i on X-100 o wo hou s
a 4 °C and hen wo hou s a oom empe a u e. The
ma e ial was embedded in a mix u e o 90% glyce ol
and 10% PBS wi h DABCO. Op ical sec ions we e
digi ally eco ded using a Nicon A1 con ocal lase -
scanning mic oscope. Images we e p ocessed using
ImageJ and Ami a so wa e.
Resul s
Mo phology o la a
The la ae o Ba en sia g acilis a e abou
150 mic ons in size. The shape o he la al body
esembles a bell. A la ge non-cilia ed episphe e
and a low cilia ed hyposphe e a e sepa a ed by
a p o o och. The p o o och is loca ed on a old
o he body called he p o o ochal old (Fig.
1A). A cilia ed apical o gan lies a he apex o
he episphe e (Fig. 1A, B). I can e ac in o he
episphe e, o ming an apical pi . A cilia ed on al
o gan lies on he an e io side o he la al body,
коннективами, парные нервы передней части ноги, нервы ноги и фронтальные не-
рвы, несколько тонких поперечных нервов эписферы и нервное кольцо прототроха.
Как цитировать эту статью: Bo isano a A.O. 2025. Myoana omy and ne ous sys em o
a swimming- ype la a Ba en sia g acilis (En op oc a: Coloniales) // In e . Zool. Vol.22.
No.1. P.21–29. doi: 10.15298/in e zool.22.1.02
КЛЮЧЕВЫЕ СЛОВА: Kamp ozoa, трохофорные личинки, иммуноцитохимия,
α-тубулин, фаллоидин, конфокальная лазерная сканирующая микроскопия.
Myoana omy and ne ous sys em o a swimming- ype la a Ba en sia g acilis 23
abo e he p o o ochal old (Fig. 1A, B). Like he
apical o gan, he on al o gan can e ac in o
he episphe e. A sli -shaped mou h opens a he
an e io ma gin o he hyposphe e (Fig. 1C). In
he cen al pa , he hyposphe e has a apezoidal
shape wi h a cen al opening h ough which he
oo udimen may pa ially ex end (Fig. 1C, D).
The oo is a cilia e in agina ion in he cen e o
he hyposphe e wi h a oo knob in he an e io
pa and a pedal cone in he pos e io pa (Fig.
1B, D). The oo knob bea s se e al bundles o
cilia, syncilia. The anus opens on he pedal cone.
Muscula u e
The muscula u e o he la a o B. g acilis
includes he muscula u e o he body wall,
muscula u e o he apical o gan, longi udinal
muscula u e o he episphe e and hyposphe e
(Figs 2A, B; 3). Nume ous ine body wall ing
muscles su ound he episphe e (Fig. 2B–D).
Ring and longi udinal muscles a e connec ed wi h
he apical o gan (Fig. 2C). The ing muscles o
he apical o gan un in he body wall in se e al
g oups unde each o he . Six longi udinal muscles
o he apical o gan a e loca ed deepe han he
Fig. 1. Mo phology o Ba en sia g acilis la ae. A — la e al iew wi h a ocus on he p o o ochal old (p );
B — la e al iew wi h a ocus on a oo udimen ( k, in and pc); C — iew on he hyposphe e o a la a
wi h a e ac ed oo udimen showing he cen al opening o he hyposphe e (co); D — la e o on al iew
on a la a wi h pa ly ex end oo udimen .
Abb e ia ions: ao — apical o gan; co — cen al opening o hyposphe e; es — esophagus; k — oo knob; o — on al
o gan; in — in es ine; in — oo in agina ion; m — mou h; pc — pedal cone; p — p o o och; p — p o o ochal old;
e — ec um; s — s omach; sy — syncilia.
A.O. Bo isano a24
Fig. 2. Muscula u e o Ba en sia g acilis la ae, CLSM. А — la e al iew o he con ac ed la ae; B — la e al
iew o he elaxed la ae; С — la e al iew o he la ae showing ing muscles o he apical o gan ( ma);
D — la e o en al iew on he hyposphe e and episphe e showing pedal muscle (p) and ec al muscula u e
( em); E — on al iew on he la a showing c ossing o c oss muscles (c m); F — la e al iew on he
muscula u e o he hyposphe e and p o o och.
Abb e ia ions: ab — abo al muscle; ab — ab on al muscle; an — an e io longi udinal muscle; bw — body wall ing
muscles; c m — c oss muscle; cu — cu ed muscle; d — do sal muscle; d m — do so en al muscle; om — muscle
o on al o gan; — on al muscle; hs — ho seshoe-shaped muscle; in — oo in agina ion; l — la e al muscle;
lh — longi udinal muscle o hyposphe e; lma — longi udinal muscle o apical o gan; lmp — longi udinal muscle o
p o o och; m — mou h; mcp — main cons ic o o p o o och; ob — oblique muscle; p — pedal muscle; em — ec al
muscula u e; ma — ing muscle o apical o gan; mh — ing muscle o cen al opening o hyposphe e; mp — ing
muscle o p o o ochal old.
Myoana omy and ne ous sys em o a swimming- ype la a Ba en sia g acilis 25
Fig. 3. Schema ic diag am o he muscula u e o
Ba en sia g acilis la ae.
Abb e ia ions: ao — apical o gan; ab — abo al muscle;
ab — ab on al muscle; an — an e io longi udinal muscle;
bw — body wall ing muscles; c m — c oss muscle; cu —
cu ed muscle; d — do sal muscle; d m — do so en al
muscle; ep — episphe e; k — oo knob; o — on al
o gan; om — muscle o on al o gan; — on al muscle;
hp — hyposphe e; in — oo in agina ion; l — la e al
muscle; lh — longi udinal muscle o hyposphe e; lma —
longi udinal muscles o apical o gan; lmp — longi udinal
muscles o p o o och; mcp — main cons ic o o p o o och;
ob — oblique muscle; p — pedal muscle; pc — pedal cone;
ma — ing muscles o apical o gan; mh — ing muscles
o cen al opening o hyposphe e; mp — ing muscles o
p o o ochal old.
ing muscles (Fig. 2B, C, E). These muscles
o m a kind o baske a ound he apical o gan.
They a e ela i ely sho and end in he uppe
hi d o he episphe e. In he con ac ed la a, a
ho seshoe-shaped muscle is isible in he api-
cal pa o he episphe e, wi h i s a c di ec ed
o wa d (Fig. 2A, E). A pai o longi udinal
an e ial muscles inse in on o he a c o he
ho seshoe-shaped muscle (Fig. 2A, B, E). They
end a he le el o he middle o he episphe e.
The pai ed cu ed muscles o igina e nea he
mou h opening (Fig. 2D), un obliquely upwa d
o he episphe e, and end in he body wall in
he a ea abo e he on al o gan (Fig. 2A, B).
A pai o oblique muscles p o udes om he
a ea abo e he on al o gan below he cu ed
muscles and ex ends owa d he pos e io wall
o he esophagus (Fig. 2A, B). The pai ed on al
muscles un om he oo knob (Fig. 2D) o he
pos e io pa o he apical o gan, whe e i spli s
in o wo bundles (Fig. 2A, B). The pai ed do sal
muscles o igina e behind he apical o gan and
un o he abo al side o he la a’s body. A pai
o ab on al muscles uns a he pos e io pa
o he la al body in he uppe hal o episphe e
(Fig. 2A, B). The pai ed abo al muscles inse
wi h small b anching ib es a he uppe pa o
he pos e io side o he body, un pa allel o he
ab on al muscles and end a he bo de be ween
he episphe e and hyposphe e (Fig. 2A, B). Two
pai s o c oss muscles un om he on al o
he ab on al side o he la al body a he le el
abo e he middle o he episphe e (Fig. 2B, C).
These muscles c oss each o he on he on al
side o he body (Fig. 2E). The pai ed muscles
o on al o gan inse a he sides o on al
o gan, i s go upwa d, and hen u n la e ally
and un owa d he ab on al side o he body
(Fig. 2A, B). Th ee pai s o do so en al muscles
a e loca ed on he sides o he la al body in i s
pos e io hal (Fig. 2A, D). They un om he
hyposphe e o he middle pa o he episphe e.
Two pai s o la e al muscles inse abo e he
oo in agina ion (Fig. 2D) and un upwa d and
la e ally, w apping a ound he s omach (Fig. 2A,
B). In he diges i e ac , he muscula elemen s
a e iden i ied in he lowe hi d o he ec um,
nea he anus — ec al muscula u e (Fig. 2D).
The p o o ochal old con ains a b oad band
o ing muscles — a sphinc e o he p o o och
(Figs 2A–C; 3). The sphinc e includes a num-
be o muscle ibe s loca ed close o each o he ,
he ing muscles o p o o ochal old, and one
hick muscle ibe below hem — he main
cons ic o o p o o och (Fig. 2B, C). The main
cons ic o is unclosed on he ab on al side.
In he con ac ed la a, he main cons ic o is
loca ed abo e he ing muscles o p o o ochal
old. The longi udinal muscles o he p o o och
inse wi h small b anching ib es nea he main
cons ic o o p o o och and ex end in o he
episphe e, ending in i s lowe hi d (Fig. 2B).
Longi udinal muscles o p o o och a e loca ed
along he pe iphe y o he body a app oxima ely
equal dis ances om each o he .
In he cen al pa o he hyposphe e he e is
a g oup o ing muscles o hyposphe e su ound-
ing he cen al opening h ough which he oo
udimen ex ends (Fig. 2E). The longi udinal
muscles o hyposphe e un om he a ea o he
cen al opening o he an e io end o he body
A.O. Bo isano a26
Fig. 4. Ne ous sys em o Ba en sia g acilis la ae, CLSM. A — la e al iew on he la a showing apico-
on al connec i e (a n) and ne es o igina ed om he on al ganglion; B — la e al iew on he la a
showing b anches o oo ne es (b n); C — la e al iew on he la a showing ne e ing o p o o och (n );
D — la e al iew on he la a showing ans e se ne es o episphe e ( n).
Abb e ia ions: a n — apico- on al connec i e; ao — apical o gan; an — ine apical ne es; b n — b anch o oo ne e;
g — on al ganglion; kn – oo knob ne e; n — oo ne e; o — on al o gan; n — on al ne e; n — ne e ing
o p o o och; p — p o oneph idium; n — ans e se ne e o episphe e.
ganglion hese ine ne e ibe s (apical ne es)
me ge in o a pai o apico- on al connec i es
unning o he on al ganglion (Figs 4A; 5).
Se e al pai s o la ge ne es o igina e om he
on al ganglion. A pai o on al ne es p ojec s
om he on al ganglion owa d he mou h and
con ac s a ne e ing o p o o och (Figs 4A;
5). The ne e ing o p o o och uns along he
p o o och (Figs 4C; 5). The oo knob ne es
sepa a e om he on al ne es and ex end
owa d he oo knob (Figs 4A; 5). Pai ed oo
(Fig. 2D, E). The pai ed a c-shaped pedal muscles
a e loca ed on he sides o he oo in agina ion
(Fig. 2D, F).
Ne ous sys em
The ne ous sys em o en op oc la ae
includes wo la ge sensi i e o gans, apical and
on al, associa ed wi h apical and on al gan-
glia, espec i ely. Fine ne e ibe s un om he
senso y o gans o he ganglia (Figs 4A, B; 5). In
case o he apical o gan, a he base o he apical
Myoana omy and ne ous sys em o a swimming- ype la a Ba en sia g acilis 27
ne es ex end om he on al ganglion owa d
he oo (Figs 4A; 5). Nea he oo in agina ion,
he oo ne es spli in o se e al ne e ibe s,
some o which con ac he in agina ion o he
oo , and some o which ex end u he o he
abo al side o he la al body as b anches o
oo ne e (Figs 4B; 5). The episphe e con ains
se e al pai s o ine ans e se ne es ha s a
om he on al ganglion and ex end o he abo al
side o he body, whe e spli in o ine ne e ibe s
con ac ed he body wall (Figs 4D; 5).
Discussion
Muscula u e
The muscula u e o he la a o B. g acilis is
complex and con ains a la ge numbe o muscles
unning in di e en di ec ions. The unc ion o
some muscles can be assumed by compa ing
he a angemen o muscles in a con ac ed and
elaxed la a. The longi udinal muscles o he
p o o och a e in ol ed in he e ac ion o he
hyposphe e deep in o he la al body. The main
cons ic o o he p o o och in he con ac ed
la a is loca ed abo e he ing muscles o he
p o o ochal old, and his means ha he hy-
posphe e is no jus pulled up o he episphe e,
bu is also u ned inwa ds. Re ac ion o cen al
pa o hyposphe e is p obably p o ided by he
do so en al muscles and also by la e al muscles.
The oblique and on al muscles a e p obably
esponsible o e ac ion o he an e io pa o
he hyposphe e. The longi udinal muscles o he
apical o gan and he muscles o he on al o gan
a e esponsible o he e ac ion o hese o gans.
Compa ison o he muscula u e o B. g acilis
wi h ha o swimming- ype la ae wi h a com-
ple ely educed oo shows ha he muscula u e
o he la e is less complex (Bo isano a e
al., 2012; Fuchs, Wanninge , 2008) (Fig. 6A).
Some muscles can be ound bo h in la ae wi h
a comple ely educed oo and in la a o B.
g acilis wi h a pa ially educed oo : he ing
and longi udinal muscles o he apical o gan,
he ing muscles o he p o o och (including
he main cons ic o ) and longi udinal muscles
o he p o o och, as well as he ing muscula-
u e o he body wall. The pai ed longi udinal
muscles desc ibed in swimming- ype la ae
wi h a comple ely educed oo ( on al muscles,
ab on al muscles, la e al muscles, main e ac o
muscles), a e di icul o homologize unambigu-
ously wi h he muscles o B. g acilis. The main
e ac o s desc ibed in L. a kinsae (Fuchs, Wan-
ninge , 2008) and he cen al muscles desc ibed
in B. disc e a (Bo isano a e al., 2012) mos
likely co espond o he on al muscles o B.
g acilis. The abo al muscles o swimming- ype
la ae wi h a comple ely educed oo may co -
espond o he abo al muscles o B. g acilis.
The on al muscles o swimming- ype la ae
wi h a comple ely educed oo ha un om he
apical o gan o he p o o och nea he an e io
end o he body and c oss each o he , canno be
homologize wi h any o B. g acilis muscles. B.
g acilis has in e c ossing c oss muscles bu hey
un in a di e en di ec ion, om he an e io o
he abo al side o he body.
The muscula u e o he c eeping- ype la a
o L. mu manica (Me kel e al., 2015) wi h a
well-de eloped oo and on al o gan is mo e
complex han ha o B. g acilis (Fig. 6B). The
la a o L. mu manica (as well as swimming- ype
la ae) has ing and longi udinal muscles o he
apical o gan, ing and longi udinal muscula u e
Fig. 5. Schema ic diag am o he ne ous sys em o
Ba en sia g acilis la ae.
Abb e ia ions: a n — apico- on al connec i e; ao — apical
o gan; ag — apical ganglion; an — ine apical ne es; b n —
b anch o oo ne e; ep — episphe e; g — on al ganglion;
k — oo knob; kn — oo knob ne e; n — oo ne e;
o — on al o gan; n — on al ne e; hp — hyposphe e;
in — oo in agina ion; n — ne e ing o p o o och;
pc — pedal cone; n — ans e se ne e o episphe e.
A.O. Bo isano a28
Fig. 6. Schema ic diag am o he muscula u e o swimming- ype and c eeping- ype en op oc la ae. A —
swimming- ype la a wi h a comple ely educed oo . B — c eeping- ype la ae.
Abb e ia ions: ab — abo al muscle; ab — ab on al muscle; d — do sal muscle o on al o gan; d — do so en al
muscle o on al o gan; d m — do so en al muscle; — on al muscle; l — la e al muscle; lma — longi udinal muscle
o apical o gan; lmp — longi udinal muscle o p o o och; mcp — main cons ic o o p o o och; m m — main e ac o
muscle; p — pedal muscle; — e ac o o on al o gan; ma — ing muscle o apical o gan; mp — ing muscle o
p o o ochal old; — en al muscle o on al o gan.
side, while in B. g acilis no in e c ossing o hese
muscles is ound. In bo h L. mu manica and B.
g acilis, pai ed on al muscles ex end om
he an e io end o he oo o he apical o gan.
In bo h species, se e al pai s o do so en al
muscles a e loca ed in he pos e io hal o he
body. The la e al muscles o L. mu manica a e no
homologous o he la e al muscles o swimming-
ype la ae wi h a comple ely educed oo , no
o he la e al muscles o he la ae o B. g acilis.
In L. mu manica la e al muscles inse be ween
apical and on al o gan and un ab on ally,
ending nea he hyposphe e.
Ne ous sys em
The ne ous sys em o en op oc la ae
has p e iously been s udied using con ocal
mic oscopy me hods in only wo species: he
swimming- ype la a o Loxosomella a kinsae
wi h a comple ely educed oo and on al o gan
(Fuchs, Wanninge , 2008) and he c eeping- ype
la a o L. mu manica (Wanninge e al., 2007). In
bo h cases, he se o one gic ne ous sys em was
in es iga ed. This makes i somewha di icul
o compa e wi h he da a ob ained in he p esen
s udy, which used labeling wi h an ibodies o
α- ubulin. Howe e , gi en ha ubulin is p esen
in all elemen s o he ne ous sys em, including
o he p o o och, and abo al muscula u e. Some
muscles associa ed wi h he on al o gan and
oo a e simila in L. mu manica and B. g acilis,
al hough hese muscles a e less de eloped in B.
g acilis, because bo h he on al o gan and he
oo a e pa ially educed. Thus, in L. mu manica,
se e al g oups o pai ed muscles ( e ac o s o
he on al o gan, do sal muscles o he on al
o gan, do so en al muscles o he on al o gan
and some o he muscles) inse om he la ge
on al o gan and un owa ds he apical o gan
and he uppe pa o he episphe e. In B. g acilis,
he on al o gan is small and only a pai o he
on al o gan muscles o igina es om i . How-
e e , B. g acilis has se e al pai s o muscles
o igina ing om he a ea abo e he on al o gan,
simila in loca ion o he some muscles o L.
mu manica o igina ing om he on al o gan.
Fo example, c oss muscles o B. g acilis a e
loca ed simila ly o he b anched do sal muscles
o he on al o gan o L. mu manica, al hough
he la e do no c oss each o he . The posi ion o
he b anched en al muscles o he on al o gan
o L. mu manica is simila o he posi ion o he
oblique muscles o B. g acilis. In bo h species
he a c-shaped pedal muscles a e connec ed o
he oo , bu in L. mu manica he le and igh
pedal muscles c oss each o he on he abo al
Myoana omy and ne ous sys em o a swimming- ype la a Ba en sia g acilis 29
se o one gic elemen s, some compa a i e analy-
sis can s ill be made. The se o one gic ne ous
sys em o L. a kinsae includes he se o one gic
cells o he apical o gan, ne es unning om
he apical o gan o he on al neu opil on he
on al side o he la a, and ne es unning
om his neu opil o he ne e ing o he p o-
o och. All hese ne e elemen s we e ound in
B. g acilis: apico- on al connec i es linking
apical and on al ganglions and on al ne es
unning om he on al ganglion o he ne e
ing o he p o o och. These ne e elemen s can
also be iden i ied in he c eeping- ype la a o
L. mu manica (Wanninge a al., 2007: ig. 2c).
The on al neu opil has no been desc ibed in
L. mu manica, bu i is p obably loca ed whe e
he bundles o ne es coming om he apical
ganglion (co esponding o he apico- on al
connec i es) spli in o sepa a e ne es. These
a e ne es connec ing o he an e io ne e loop,
ne es inse ing a he pedal ne e co ds, and
ne es unning en ally and inse ing a he
p o o och ne e ing. The la e co espond
o he on al ne es o B. g acilis. The pai ed
longi udinal pedal ne es, desc ibed in L. mu -
manica, a e di icul o homologize wi h he
ne es desc ibed in B. g acilis. Acco ding o he
au ho s’ desc ip ion (Wanninge a al., 2007),
he pedal ne es o L. mu manica “pass h ough
along he an e io –pos e io axis in he mid-body
egion o he la a”, bu he oo is loca ed in
he lowe pa o he la a’s body, so i is no
ce ain ha hese ne es a e, indeed, connec ed
o he oo . The pedal ne es o B. g acilis un
om he on al ganglion en ally, o he oo
in agina ion.
Gene aliza ion o he da a ob ained by con o-
cal mic oscopy and o he me hods o esea ch
(Nielsen, 1971; Nielsen, Jespe sen, 1997; Hasz-
p una , Wanninge , 2008; Bo isano a, I ano a,
2024) allows o iden i y he ollowing obliga o y
elemen s o he ne ous sys em o en op oc
la ae: apical and on al ganglia connec ed by
apico- on al connec i es; se e al pai s o ne es
depa ing om he on al ganglion, including
he on al ne es going o he ne e ing o he
p o o och.
Acknowledgemen s. The au ho is hank ul
o he managemen and s a o Pe so Whi e Sea
Biological S a ion o Lomonoso Moscow S a e Uni-
e si y (WSBS MSU) o p o iding he oppo uni y o
conduc he esea ch and especially o WSBS di ing
eam and o he s a o he cen e o mic oscopy o
WSBS. The au ho is g a e ul o he Re iewe o
help ul commen s.
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Responsible edi o s: A.V. Che nyshe ,
E.N. Teme e a
