Contributions to Zoolog)’, 68 (3) 143-160 (1999)
SPB Academic Publishing hv, The Hague
Scanning electron microscopy of acrothoracican cypris larvae (Crustacea,
Thecostraca, Cirripedia, Acrothoracica, Lithoglyptidae)
¹, ¹ Gregory+A. Kolbasov Jens+T. Høeg² & Alexei+S. Elfimov
1 Department of Invertebrate Zoology, Biological Faculty, Moscow State University, Moscow 119899,
2 Russia; Corresponding author. Department of Zoomorphology, Zoological Institute, University of
Copenhagen, Universitetsparken 15, DK-2100, Copenhagen, Denmark, e-mail: [email protected]
words lattice Key : Cirripedia, Acrothoracica, Ascothoracida, cypris larva, morphology, organ. SEM,
phylogenetic relationships, larval characters
Abstract Antennulary segments 151
Thorax and thoracopods 153
and furcal rami 154 used to full Hindbody Scanning electron microscopy was provide a Discussion 154 morphological description ofcypris morphologyin the acrothora- 155 Lattice organs cican species Lithoglyptes milis and L. habei (Lithoglyptidae). Mantle cavity 155 antennules, Special attention was givento lattice organs, thorax, Antennules 155 thoracopods, abdomen, and furcal rami. Cypris larvae ofthe Antennulary segment 4 156 Acrothoracica share some putative plesiomorphic features with Apomorphies in antennulary morphology 156 the cypris-like ascothoracid larvae of the non-cirripede taxon Thoracopods 156 Ascothoracida. The most notable are traces of abdominal Tagmosis and hindbody 157 and lattice without fields. segmentation carapace organs pore Conclusion 158 Acrothoracican cyprids also share numerous synapomorphies Acknowledgements 158 with those of the Thoracica and the Rhizocephala. This list References 158 with first includes a four-segmentedantennule a triangular seg- ment of two sclerites set at an angle to each other, a cylindrical
attach- second segment, a small third segment functioning asan ment fourth organ, and a cylindrical segment bearinghomologous Introduction
Further of sensory setae. apomorphies are a pair frontolateral horn glandsexiting anteroventrally on the headshield (carapace), The Cirripedia consist of the orders Acrothoracica, a pair of multicellular cement glands exiting on the attachment and the Thoracica, Rhizocephala (Hoeg, 1992; Hoeg, organs, a single stout, serrated and non-natatory seta on Both the Thoracica and the Acrothoracica thoracopodal exopods and a highly reduced abdomen with at 1995). best traces of segmentation. These synapomorphies in cypris use thoracic limbs (cirri) for setose feeding, but
a taxon Cirripedia comprising morphology support monophyletic the Acrothoracica deviate in inhabiting burrows and the Acrothoracica, Thoracica, and Rhizocephala but excluding lacking an armament of mineralized shell plates. the Ascothoracida. This cryptic mode of life has resulted in numerous
modifications to their morphology.
The Acrothoracica have long been important in Contents discussing both the evolution and phylogeny of the
Cirripedia and of the Thecostraca in Introduction 143 general
et Material and methods 144 (Glenner al., 1995; Newman, 1971, 1974, 1987;
Results 144 Spears et al., 1994; Turquier, 1972). An origin from Size and shape ofthe cyprids 145 or, more precisely, a sistergroup relationship with General morphology 145 various cirripede taxa has been suggested, such as Carapace 145 the Iblidae (Tomlinson, 1969) and the Frontolateral 145 scalpellid pores & 147 Lithotrya (Newman, 1982; Grygier Newman, Lattice organs
Mantle and mantle cavity 150 1985). In spite of these studies the position of the 144 G.A. Kolbasov, J.T. Hoeg & A.S. Elfimov — Acrothoracican cypris larvae
Acrothoracica within the Thecostraca remains un- Material and methods
clear. The lack of mineralized shell plates and
whether this is primary or due to secondary loss Most acrothoracican species brood their larva until the cypris stage is reached (Tomlinson, 1969). It is therefore possible to impedes comparison with the characters used in samplemature cypris larvae from the mantle cavities offemales estimating the phylogeny of thoracican barnacles found in museum collections. Acrothoracican males are always (Glenner et ah, 1995, Newman, 1996). Spears et dwarf forms attached to the females (Gotelli & Spivey, 1992;
ah used molecular data in an effort to (1994) clarify Kolbasov, 1996).
cirripede phylogeny and their results suggested We examined the collections ofmollusc shells stored in the
between the Zoological Museum ofMoscow State University and found more an affinity Acrothoracica and the than 300 specimens containing Acrothoracica. Many of them Ascothoracida, which challenged even the basic hosted either habei or L. mitis and some contained Lithoglyptes , monophyly of the Cirripedia. Despite the wide cypris larvae. Recently settled cypris stages ofdwarf males (Fig.
morphological differences adult Thecostraca, and females also among 2C) were isolated.
of each All was in 70% alcohol. We most representatives group possess pelagic material preserved investigated
larvae L. nauplius and cypris-like larvae. The similarity and five Lithoglyptes habei cypris and five mitis cypris larvae with SEM and also mounted for we some light microscopy unproblematic homology of these larvae includ- after KOH treatment. All larvae for SEM investigation were ing numerous details apparent under the scanning post-fixed with 2% 0s0 for 2 hrs, dehydratedin acetone, and 4 electron microscope make them eminently suited critical point dried in CO Dried specimens were sputter-coated r for the within resolving phylogenetic relationships with gold and examined at 15 kv accelerating voltage (with a
in the Thecostraca (Grygier, 1987a, b; Walossek et JEOL JSM-840 SEM Copenhagen and a HITACHI S405A SEM in After of external Moscow). investigation carapace ah, 1996). Jensen et ah (1994) used SEM on cypris
features one“valve” of some larvae was removed to reveal the larvae to study the recently discovered lattice or- body. gans in the carapace. They found putative plesio- The material studied came from the following localities. morphic similarities between Ascothoracida and Lithoglyptes habei: Gulf ofAden, 13°59’5”N,48“24’7”E,depth
Acrothoracica and putative synapomorphies be- 3 m, coral reef, I female with 1 cypris inside, in Turbo argiro-
Seychelles, Silhouette 1.,4"36’5, 56°48’E, subtidal zone, tween Acrothoracica and the remaining two stomum; 6 females and I free cypris in Mancinella mancinella; South cirripede orders. Moyse et ah (1995) employed SEM China Sea, Vietnam 12°N, 109"E: depth 1.5 m, 3 females (1 on cypris attachment organs in a wide selection of with a cypris inside) in Mancinella mancinella; depth 2 m, 2
These two studies focussed on females and 1 free in 2-4 5 cirripede cyprids. cypris Coralliophila deformis; m,
but few selected and all works females with a in a organs, previous (1 cypris inside) Drupa morum.
Lithoglyptes mitis: Maldives: Feartu I., 3°48’N, 73°05’E, on acrothoracican cyprids used only light micros- intertidal females zone, coral reef, 8 (1 with a cypris inside); copy (Kuhnert, 1934; Tomlinson, 1969; Turquier, Genego I., 3°49’N, 73°06’E intertidal and subtidal zones, coral 1967, 1970, 1971, 1985; Wells & Tomlinson, 1966). reef, 2 females and 1 cypris with stretched antennules in Trochus
For acrothoracican cyprids we therefore lack the pyramis, 17 females (2 with a cypris inside) in Mancinellaalauina, level of detail now available from the two other t 8 females (1 with a cypris inside) in Latirolagenasmaragdula,
3 female with in Morula cirripede orders (e.g., Elfimov, 1995; Glenner et specimens (1 a cypris inside) cavernosa ,
2 females (1 with a cypris inside) in Hipponix ah, 1989; Glenner & Hoeg, 1995; Hoeg, 1985; sp.
Jensen et ah, 1994; Moyse et ah, 1995; Walker,
1985; Walker et ah, 1987). An ultrastructural study Results of the entire morphology ofan acrothoracican cyprid
is necessary for gathering the suite of larval char- could detect We not any morphological differences acters that Glenner et ah (1995) advocated for fu- between cypris larvae ofLithoglyptes habei and L. ture studies of cirripede phylogeny. Here we try to mitis. We have therefore not distinguished between in accomplish this part by a study of cypris mor- the two species in the following description, but phology in two species of the acrothoracican fam- the species name is provided for all figures. ily Lithoglyptidae. 145 Contributions to Zoology, 68 (3) - 1999
of Size and shape of the cyprids and attach to the dorsomedial side the carapace,
of the but a complete description cypris muscula-
contained will in In our material the adult females never ture require section series as Walley (1969)
oral more than a single cypris, while Tomlinson (1969) and Hoeg (1985). The undifferentiated (buc-
within the often found two brooded larvae in the same female. cal) cone and the thorax lie posterior
located in the lower halfof the The thorax carries six of The brooded cypris larvae are carapace. pairs
the and body part of female usually towards the biramous limbs armed with long natatory setae. The dorsal margin of mantle cavity. They measure ca. abdomen is rudimentary but carries a distinct tel-
with of furcal rami The 580-600 pm in length, which equals approximately son a pair (Figs. IB, 7).
40% of the length of the brooding female. The size thorax and the antennules can be partially extended ofthe cypris relative to the femalemeans that brood outside the mantle cavity (Fig. 2B,D) size is necessarily minute.
has elon- The cypris headshield, or carapace, an
gated, spindle-shaped form with an anterior rounded Carapace end end and a narrower and truncated posterior (Figs.
1B,C, 2A). The dorsal margin is slightly curved. There is no dorsal hinge line or posterior slit on
the also the At lower its surface The ventral margins of carapace are slightly carapace. magnifications curved in the anterior half, whereas in the poste- appears slightly wrinkled with small longitudinal rior halfthey are somewhat concave. The length : and transversal ridges (Fig. 2A,B), but some of these
fixa- height ratio of the carapace is ca. 3 : 1. In lateral ornaments may be artifacts produced during
At view the shape of the cypris resembles those of tion or preparation for SEM. higher magnifica- other cirripedes. However, the cyprids of both tion the carapace surface appears smooth (Fig. 3 A-D)
Lithoglyptes studied here and those of Trypetesa and without the cellular hexagonal patterning that
characterizes ascothoracid larvae lampas studied by Jensen et al. (1994) deviate from some (Ito &
facetotectan other cirripede cyprids in having a very narrow Grygier, 1990), cypris-y (Schram,
The and some thoracican The carapace compared to the length (Fig. 2A,B). 1970), cyprids. carapace functional significance of this shape is not clear. also lacks large pores (except the frontolateral
In it relate to of settle- and the wheel of Elfimov Trypetesa may peculiarities pores), papillae, organs shells Unlike of ment within the narrow confines of gastropod (1995). cyprids Cryptophialus (unpub-
inhabited by hermit crabs. lished data), there are no long setae but only minute
(0.7 pm) setae sparsely distributed over the entire
carapace (Fig. 3A,C,D). These carapace setae are
General morphology single (Fig. 3A) or double (Fig. 3C,D) and are lo-
cated in 1 wide shallow, pm depressions. Single
The general morphology of Lithoglyptes cyprids setae occur most frequently on the anterior and lateral
surfaces the A agrees with that found in other cirripedes. The of carapace. longitudinal row of
four-segmented antennules are located in the ante- double setae extends from the anterior end along
the rior mantle cavity, which occupies the anterior one the dorsomedial line of carapace (Fig. 3C,D).
third “valves” have of the cyprid Godg. The cement glands lie at The carapace deep longitudinal and
end the basis of the first antennulary segments. They transverse furrows at the anterior (Figs. 2D,
have al- a loboform shape and a brown colour (in 3C).
cohol), darker than the rest of the body. The paired
associated with frontal compound eyes, filaments,
lie in Frontolateral front of the cement glands (Fig. IB,C). The pores
situated the dorsal nauplius eye is near margin, one
third of the length from the anterior end. Retractor Lithoglyptes cypris larvae lack the frontolateral horns
muscles of the antennules and thorax extend through found in a few thoracican species, but sport a pair
the anterior of and middle parts of the cypris body conspicuous frontolateral pores near the 146 G.A. Kolbasov, J.T. Haeg & A.S. Elfitnov — Acrothoracican cypris larvae
Fig. I. A, Lithoglyptes mitis, adult female, lateral view, with a cypris (bottom arrow) and an unidentified copepod (top arrow) inside the mantle cavity, lateral view; B,C, L. habei cyprid, lateral view from light microscopy; D, terminal part of antennule showing attachment disc on 3rd segment (3) with dense carpet of cuticular villi (see Fig. 5D); E, Setation on fourth antennulary segment,
five terminal minute C Setation of in among setae (TS) only seta identified (See Fig. 6D); F, (arrowheads) terminal (2nd) segment
of thoracopodal exopod, isolated basal seta, three subterminal and two terminal setae closely grouped; G, Setation (arrowheads)
of three Terminal end of furcal with terminal (3rd) segment thoracopodal endopod, terminal setae; H, ramus two setae (arrowheads)
CE CG of inside mantle FR furcal LOl-5 lattice (See Fig, 7G). compound eye, cement gland, CT, rows ctenes cavity, ramus, organs
M NE PAS RS radial 1-5, extrinsic antennulary muscles, nauplius eye, OC, oral cone, postaxial sensillum, PS2 postaxial seta 2, setae,
SC proximal sclerite of 1st antennulary segment, SK skirt encircling attachment disc, SSI-4 subterminal setae 1-4, TE telson, TH thorax, TUP thoracopods, TS terminal setae, 1-4 antennulary segments. Scale bars in pm. Contributions to Zoology, 68 (3) - 1999 147
2. L. with extended arrowheads show Fig. Cyprids (A,D Lithoglyptes mills ; B,C habei). A, antennule, ventrolateralview, entrance to
mantle cavity; B, with both antennules and thoracopods extended, lateral view; C, settled male cyprid removed from female mantle
cavity, female tissue remains around antennules(arrowhead); D, anterior end with extended antennule, ventrolateralview, arrowheads
THP denote anterior furrows. AN antennule, FP frontolateral pore, PS2 postaxial seta 2, thoracopods, 2-3 antennulary segments.
Scale bars in pm.
80 dian keel L03 and but anteroventral margin of the carapace ca. pm or crest (in L04), are never
from the The encircled cuticular anterior end (Figs. 2D, 3B,E). pores by a ridge. This means that the
1.3 LOs of have are elongate (3 by 4 pm) and surrounded by a pm Lithoglyptes the same morphology
in a found al. high cuticular ridge without any sculpture. They {‘keel trough’) as by Jensen et (1994)
are the exits for the frontolateral glands that char- in cyprids of T. lampas. The elongate depression
acterize cirripede cyprids. of the LOs has a latticed bottom due to minute
perforations in the epicuticle, but a TEM investi-
of similar in the T. gation organs acrothoracican
revealed that lack in the under- Lattice organs lampas they pores
lying procuticle (Hoeg et al., 1998).
The carapace has five pairs of lattice organs (LO) Terminal pore: A conspicuous terminal pore (TP) in both Lithoglyptes habei and L. mitis. They have lies at the posterior end of LOl and L03-5, but
the of the differs in same position and the same morphology L02 having this pore sited at the anterior
individual the five LO found in end organs as pairs (Fig. 4A-D).
Trypetesa lampas by Jensen et al. (1994). Position and shape: The first (LOl) and second
Individual All individual lattice of lattice lie close morphology: or- (L02) pairs organs (10 pm) to-
are 7-18 and 0.8-1 wide ca. 200 from the anterior end and 5-13 gans shallow, pm long pm gether, pm pm
from depressions (Fig. 4). They may have a weak me- the dorsal midline (Fig. 4A,B). LOl is straight 148 G.A. Kolbasov, J.T. Haeg & A.S. Elfimov- Acrothoracican cypris larvae
Fig. 3. Cyprids (A-B Lithoglyptes mitis, C-E L. habei). A, anterior end, oblique lateral view, setae arrowed; B, anterior end, ventral view front view of and showing entrance to mantle cavity with antennule (AN), at upper left, C, anteriorend, dorsal carapace, furrows
with raised double seta (arrowed); D, dorsal margin of carapace, double setae arrowed; E, frontolateral pore (of frontolateral gland)
AN FP frontolateral Scale bars in rim. antennule, pore. pm. Contributions to Zoology, 68 (3) - 1999 149
4. lattice numbered C L. left lattice 1 and Pig. Cyprid carapace, organs (A,B,D,E Lithoglyptes mitis cyprid; habei). A, side, organs 2
anterior end is terminal in 1 but anterior in left (small arrowheads), left, pore (TP) posterior lattice organ lattice organ 2; B, side, lattice
terminal anterior end is lattice 3 and both with organ 2, pore (TP) anteriorly sited, left; C, posterior end, right side, organs 4, posteriorly
sited terminal end is lattice left sited terminal anterior end is pore (TP), anterior right; D, organ 5, side, posteriorly pore (TP), left; E,
and anterior end is left. bars posterior end, showing relative position of lattice organs 3, 4 5, Scale in pm. 150 G.A. Kolbasov, J.T. Haeg & A.S. Elfimov - Acrothoracican cypris larvae
5. C L. anterior left of removed of mantle Fig. Cyprids (A,B,D Lithoglyptes habei; milis). A, end, side carapace to expose inner side with rows ofcuticular ctenes (CT, arrowheads) and semiparallel rods of proximal sclerite (SC) of the first antennulary segment; B, detail ofA, cuticle ofmantle cavity with ctenes (CT, arrowheads); C, anterior end, right side of carapace and right antennule removed
(breakage at *) exposing left antennule with anteriorly projecting proximal sclerite (SC), white arrowheads show cuticular fold close to ventral mantlemargin; D, distal part of antennule (segments 2-4). AD attachment disc,AM arthrodial membrane (between segment
2 and 3), CT ctenes, PS2 postaxial seta 2, RS radial setae (arrowheads), SS1 -4 subterminal setae (on segment 4), TS terminal setae (on
SC sclerite of 2-4 Scale bars in segment 4), proximal antennulary segment 1, antennulary segments. pm.
and 7 L02 is and Mantle and mantle (tin long. longer (18 pm) very cavity slightly curved. The three posterior pairs (L03-5) are located ca. 300 pm behind the anterior pairs The inner surface of the mantle has a longitudinal and close the fold from are (100 pm) to posteriormost end of 18 pm distant the ventralmost edge (Fig. the cypris (Fig. 4E). L03 and L04 are separated 5C, white arrowheads). In the anterior mantle cav- by only 4 pm and lie approximately in line with ity the cuticle also has five longitudinal rows of
LOI and L02 from the dorsal cuticular to the ventral (4-5 pm midline). ctenes running parallel edge
LOS lie level with L04 but distant of the These about are more carapace. rows are separated by
(16-18 from the pm) midline (Fig. 4E). L03 and 11 pm and their 3-4 pm high ctenes consist of
L04 and are 8-10 pm long straight or only slightly unfused fringes (Figs. 1C, 5 A,B). We were not able curved. LOS is 7 in only pm long. to verify whether similar ctene rows occur the Contributions to Zoology, 68 (3) - 1999 151
Fig. 6. Cyprid antennule(A,C Lithoglyptes mitis; B,D L. habei). A, attachment disc (AD) of segment 3 with dense carpet of cuticular
villi and skirt black and of encircling (SK), arrowheads point to insertion (left) apex (right) postaxial sensillum (PAS); B, dorsal
(preaxial) side of segment 3 showing insertion of segment 4 and diminutivepostaxial seta 3 (PS3); C, segment 3, right lateral view of
of terminal minute right antennule; D, distal end segment 4, four subterminal setae (SSI-4), among five setae (TS) only seta C named,
other clockwise: first thin seta with distended base and distal second thin thick TS (see text) are long seta, taper, long, seta, cylindrical
seta. AD attachment disc, (C) terminal seta C, PAS postaxial sensillum, PS2 postaxial seta 2, PS3 minute postaxial seta 3, SK
cuticular skirt encircling attachment disc, SSI-4 subterminal setae (on segment 4), TS terminal setae (on segment 4), 3-4 antennulary
Scale bars in segments. pm.
posterior part of the mantle cavity. (Terminology without setae. As in all cirripedes this segment has
on ctenes and fringes adapted from Grygier (1987b) a conical or triangular shape and consists of two
and Klepal & Nemeschkal (1995).) sclerites (see detailed description in Hoeg, 1985
and Glenner, in press). The proximal sclerite forms
the base of the cone and carries two anteriorly pro-
1st antennulary segment jecting rods (SC in Fig. 5C). The distal sclerite
connects with the cylindrical second segment at the
As in all other the antennules of the The be cirripede cyprids apex cone. segment can completely
of mantle consist four segments (Figs. IB, 2D, 5C,D, 6). withdrawn inside the cavity, but projects
The first segment (Figs. 1C, 5C) is largest, about outside during exploratory walking and in attach-
80 pm long and 40 pm wide, flattened laterally and ment (Figs. 1C, 2C). 152 G.A. Kolbasov, J.T. Hoeg & A.S. EIJimov — Acrothoracican cypris larvae
7. end ofthorax and left removed Fig. Cyprid, posterior (L. habei). A, posterior part abdomen,part of side carapace (arrowheads); B, thorax, dorsal view; C, thorax, dorsolateral view, terminal segments ofexopod (EX) and endopod(EN) ofleft thoracopod 3, arrowheads
of three thoracic and indicate single basal seta and five terminal setae in exopod; D, detail A, showing last segments (TH 4-6)
5 and from thoracic 5 due directed basalmost limb thoracopods 6, thoracopod 6 may appear to originate segment (TH5) to anteriorly part (BA), thoracopod 6 with three-segmented endopod (1-3, white arrowheads) and two-segmented exopod (1-2, black arrowheads),
2" are serrated shows (I", exopod segments of thoracopod5), exopod segments 1 with single long and seta (SES arrowheads), arrow terminal offurcal is natatory setae onexopod segment 2; E, proximal-middlepart ramus, lateral view, distal end down;F, posteriormost Contributions to Zoology, 68 (3) - 1999 153
4th 2nd antennulary segment antennulary segment
The second is 75 The fourth measures 5 cylindrical segment ca. pm long, cylindrical segment jam by
4 the with a straight ventral (postaxial) and curved dor- pm and inserts laterally on third segment (Figs. sal (preaxial) margin (Fig. 5C). Its width decreases 5D, 6A-D). As in thoracican cyprids (Clare & Nott,
from at the the carries four subterminal and five 35-40 pm proximal ly to only 12-13 pm 1994), segment articulation to the third segment. A conspicuous terminal setae (Figs. IE, 6D). Our terminology of postaxial seta 2, number 13 in the classification of these setae follows the scheme of Gibson & Nott
Nott & Foster (1969), inserts ventrodistally (Figs. (1971) and also used by Clare & Nott (1994),
Glenner& 1D, 5D) as in the groundpattern for cirripede cyprids Hoeg (1995) and Walossek et al. (1996).
(Glenner et ah, 1989; Moyse et ah, 1995). There All setae ofthe fourth segment, except the diminu-
second have are no other segmental setae, but a small tive seta C, an apical pore.
ctene (7-10 fringes) adorns its lateral surface closer The four subterminal setae (setae 1-4) are situ-
the to the basal margin than to distal one. ated close together. They are morphologically iden-
tical, approximately equal in length (9 pm), and
resemble those in thoracican barnacles (SSI-4 in
3rd antennulary segment Fig. 6D).
The of the five terminal homologies setae are
The hoof-shaped third segment measures ca. 30 by discussed below. They differ in regards to length,
15 All pm (Figs. ID, 5D, 6A,C). surfaces except width, and morphology, but not to the extent seen
the attachment disc lack setae. A well-developed in the Thoracica (Gibson & Nott, 1971; Clare &
skirt of thin cuticle (sensu Moyse et ah, 1995) Nott, 1994; Glenner & Hoeg, 1995). In particular,
encircles the attachment disc, which is morphologi- all terminal setae in Lithoglyptes are unsetulated,
cally ventral (Figs. 5D, 6A,C) and is covered by a whereas in thoracicans two terminal setae (A & B)
dense carpet of cuticular villi (Figs. ID, 6A). We have long setules. In Lithoglyptes, two setae are
failed 8-9 and of form. to detect an axial sense organ (sensillum), pm long, narrow, simple One seta
the in but in other cyprids it is often obscured by (C) is vestigial, just as the Thoracica. The long-
but cuticular villi (Moyse et ah, 1995). A well-developed est seta (13 pm) has a distended basal half, tapers
sensillum inserts the rather at around 2/3 rds of the towards postaxial (PAS) at postaxial abruptly way
margin of the segment (Figs. ID, 6A) between the the tip; its surface shows a faint circular or spiral
skirt and the carpet of villi. Two setae situated at pattern that indicates a reinforcement structure in
the of the attachment disc otherwise thin cuticle. distal, preaxial margin an very Finally, one c. 9 pm
(Figs. ID, 5D) represent two of the radial sensilla long, cylindrical and isodiametrical seta has a width
of thoracican cyprids, but there could well be ad- in between the two thin setae and the thick seta
ditional radial sensilla hidden in the carpet of villi. and terminates very abruptly.
An indistinct structure inserts on the lateral sur-
face near the base of the fourth segment (Fig. 6B). Thorax and thoracopods
We interpret it as a rudimentary postaxial seta 3,
in and 120 forms the third which thoracican some rhizocephalan cyprids The ca. pm long thorax posterior
inserts at this place but is a very conspicuous sen- of the cypris body (Figs. 1A,B, 7). As in other
sillum (Nott & Foster, 1969; Moyse et ah, 1995). cirripedes it consists of six segments each bearing
a pair of biramous and natatory thoracopods. In
thorax (TH), abdomen (AB), and telson (TE), ventral view, furrows indicate four putative abdominal segments (arrows), telson with
ventral distal end of furcal lateral and left furcal deep cleft (CL); G, ramus, view; H, abdomen, telson proximal part of ramus, left
lateral view, single setae (SE) on dorsal margin and setae br fringes (arrowhead) on ventral margin of telson are duplicated on
side. abdomen BA basis of CA CL cleft in CT EN EX (unseen) right AB, (but see text), thoracopod, carapace, telson, ctene, endopod,
FR furcal SES serrated seta TE TH thorax numbered in exopod, ramus, SE, seta, (on exopod segment 1), telson, (segments D),
Scale bars in l-3(white) endopodal segments, l-2(black) exopodal segments. pm. 154 G./i. Kolbasov, J.T. Hf-ieg & A.S. Elfimov - Acrothoracican cypris larvae
rhizocephalan cypris larvae Walossek et al. (1996) Hindbody and furcal rami
medioventral inserted found an unpaired process between the sixth thoracic segment and the abdomi- The hindbody consists of a short, cylindrical (6 x
with four furrows on nal rudiment, and they speculated that it might be 10 pm) abdomen, transverse
has the ventral that indicate the of a rudimentary penis. The acrothoracican cypris side, may presence
four and a x 13 telson no such process (Fig. 7D,H). segments, longer (18 pm)
We could not observe all details in each of the (Fig. 7A,D,F).
bears six individual pairs of thoracopods. Small differ- The lateral surface of the telson a row (ctene)
such between the first and second of five elongate denticles 7H). In addition there ences, as occur (Fig.
therefore have is minute seta on each side pair in the Thoracica may gone a single, dorsodistally small of undetected (Glcnner & Hoeg, 1995). The thoraco- of the telson and a group setae or fringes
the ventrodistal The pods in cyprids of Lithoglyptes resemble those laterally on margin (Fig. 7H). described using light microscopy from cyprids of ventral surface of the telson has a deep and distinct
Trypetesa nassaroides (Turquier, 1967). The thora- medial cleft (Fig. 7F). have copods consist of a protopod carrying a two-seg- The furcal rami in cyprids of Lithoglyptes
a 44 7A,E,G). mentcd exopod and a three-segmented endopod (Fig. only single pm long segment (Fig.
the 7C,D). In lateral view, pseudo-quadrangular scler- However, partially cleaved telson can easily be
the mistaken the basal of ites (Fig. 7D) cover the insertion and proximal as segments “two-segmented
rami”. bears part of the thoracopods, so we could not with cer- The lateral surface of a caudal ramus
nine tainty identify a coxa. The thoracopods bend strongly a ctene of fringes and some sparsely spaced backwards between the first ramal smaller while it termi- in the joint seg- fringes (Fig. 7E), distally
A comb of ment and the basis before they insert on the thorax nates in two long setae (Fig. 1H). cu-
(Fig. 7D,F). ticular villi surrounds the furcal setae on the dorsal
the The first exopod segment carries a single, stout margin, but are almost vestigial along ventral seta inserted laterodistally beneath a triangular margin (Fig. 1H, 7G). projection and extending beyond the second seg- ment (SES in Fig. 7D). It carries a basal row of
small spines and a single row of 8-10 much larger Discussion
second spines on the surface facing the segment.
the SEM of all Extensive bending can occur between first and This paper is the first based description
second exopodal segments. The second segment external features in acrothoracican cypris larvae.
Jensen and al. have bears five terminal simple setae and a single iso- et al. (1994) Moyse et (1995)
lated simple seta inserted near the base (Figs. IF, previously used SEM to describe individual organs
7C,D). in cyprids of Weltneria spinosa (lattice organs) and
The endopod is shorter than the exopod. The Trypetesa lampas (lattice organs, attachment or-
In position of segments in preserved cyprids show that gans). addition, Turquier (1967) gave a good
of of T. extensive bending can occur between segments two light microscopical account cyprids
nassaroides. and three. We never saw any flexure between seg-
The of in all ments one and two in the fixed specimens and sur- cyprids Lithoglyptes agree impor-
data for mise that in the live larva little or no movement tant aspects with the scattered available
We confirm occurs between them at all (Fig. 7D). The setation the other acrothoracican species. can
simi- of the endopod is difficult to observe due to obscu- that acrothoracican cyprids show numerous
ration by the exopods, but the second segment seems larities with cyprids of the remaining two cirripede
to while also in the carry one simple seta on the laterodistal margin, orders many respects resembling
the while third segment (Figs. 1G, 7C) carries three cypris-like ascothoracid larvae of the Ascothoracida.
If simple, terminal setae. correct, this setation cor- We will first discuss the individual morphological
responds exactly to that described by Turquier (1967) features concerned before we summarize their phy-
for the endopod of Trypetesa nassaroides cyprids. logenetic significance. Contributions to Zoology, 68 (3) - 1999 155
but sited in L03-5. Lattice organs L02 a posteriorly pore Jensen
et al. (1994) therefore suggested that the taxon
Lattice organs were first described by Elfimov Acrothoracica exhibits an intermediate character
and known in sited in (1986). They are chemoreceptors only state having an anteriorly pore L02 only.
from within the Thecostraca, where five pairs adorn There is nothing in our data to question that con-
the carapace of facetotectan cypris-y larvae and clusion. But Grygier & Ohtsuka (1995) found an cirripede cypris larvae (Jensen, 1993; Jensen et al., anterior position of the terminal pore in LOl and
1994; Hoeg et al., 1998; Hosfeld et al., 1998). Many L03 of Synagoga millipalus indicating that differ- ascothoracidans have fever lattice organs (Grygier, ent ascothoracidan species vary with respect to the
but with of We need pers. comm.), based on comparison the position the terminal pore. therefore a
and the fixed number in both the Facetotecta third group to clarify the plesiomorphic position
consider such ofthe terminal within the Thecostraca. This Cirripedia we cases as apomorphic pores
deviations from a thecostracan ground pattern with highlights the importance of a detailed SEM in-
the five pairs. Lattice organs (LO) vary between vestigation of the cypris-y larvae of the Facetotecta
thecostracan taxa both in their general morphol- (Hosfeld et al., 1998).
and in the the terminal ogy position of large pore, which can be sited either anteriorly or posteriorly in the individual Mantle cavity organ (Jensen et al., 1994).
Lithoglyptes habei, L. mitis, Trypetesa lampas, and of Parallel of cuticular Weltneria spinosa have lattice organs near longitudinal rows ctenes line
and the inner lamellae of the in identical morphology (“keel in a trough” type) carapace both acro- in anterior in L02 thoracican all of them the terminal pore is cyprids (present study), rhizocephalan but posterior in LOl and L03-5. This stereotyped cyprids (Walossek et al., 1996), thoracican cyprids
of the lattice within the and ascothoracid larvae morphology organs (Hoeg, unpublished)
Acrothoracica makes them well suited for discuss- (Grygier, 1987b; Ito & Grygier, 1990). This indi-
ing large scale thecostracan phylogeny. The Acro- cates that such rows represent a ground pattern thoracica “keel in feature of the Thecostraca. have lattice organs ofthe a trough" (apomorphic?) We sug-
combs morphology, but all the numerous thoracican and gest that they function as for cleaning the rhizocephalan species studied by Jensen et al. (1994) antennules.
had lattice of the field an organs “pore type”, i.e.,
oval or elongate area perforated by numerous small
in Antenmiles pores. This variation lattice organ morphology
found be among the Cirripedia can polarized by
with the Ascothoracida and 1 and 2 have a similar outgroup comparison Segments morphology very
the Facetotecta. Both have lattice that seen in other outgroups organs to cirripede cyprids. Segment 3
of the “in resembles the keel a trough” type (Jensen et al., 1994; one Moyse et al. (1995) described
Hosfeld et which indicates that this from lampas but with the differences al., 1998), Trypetesa ,
morphology is plesiomorphic within the Theco- noted below. In all cirripede cyprids, the radial setae
straca. The apomorphic “pore field” type shared are partially or wholly obscured by the microvilli
of the and by cypris larvae Rhizocephala the carpeting the attachment disc, so an exact count
Thoracica TEM indicates that these two taxa are sister requires sections in a plane tangential to the
groups, a conclusion also supported by molecular disc. This has only been done in Semibalanus
data (Spears et al., 1994). balanoides, where Nott & Foster (1969) found 8
The variation in the position of the large termi- radial setae. It is quite normal that two of the ra- nal pore is more problematic. It is posterior in all dial setae distally on the attachment disc are longer
five the pairs (LOl-5) in ascothoracidan Ulophysema than the remaining ones (Moyse et al., 1995), as
in oeresundense, whereas the Thoracica and Rhizo- also seen here Lithoglyptes, where they are the
in cephala have an anteriorly sited pore LOl and only ones visible at all. As in our study, Moyse et 156 G.A. Kolbasov, J.T. Hoeg cfe A.S. Elfimov — Acrothoracican cypris larvae
failed detect in tions both in al. (1995) to the axial sense organ exploratory walking prior to settle-
Trypetesa lampas using SEM only but revealed its ment and in permanent cementation. Important
axial could are: first presence with TEM. An sense organ apomorphies a triangular or cone-shaped
therefore also be present in our species. segment consisting of two sclerites set at an angle
In T. lampas Moyse et al. (1995) specifically to each other (see Hoeg, 1985; Glenner, in press); mentioned the absence of a postaxial seta 3 (ps3), a long, cylindrical second segment; a small third
in both the and the attachment which Thoracica Rhizocephala is a segment with organ and a cylindri- conspicuous structure that inserts near the base of cal fourth segment bearing, in the ground pattern,
is the third and fourth the 4th segment. In Lithoglyptes cyprids the rudi- 4+5 sensory setae. It seg-
knob found the insertion of that mentary adjacent to ments vary most extensively among cirripedes.
4 If This segment could represent a highly reduced ps3. is hardly surprising, since these two segments
so, this indicates that the absence or extreme re- are in direct contact with the many different types duction of ps3 is an apomorphy for the Acrotho- of substrata used in settlement by cyprids of the racica. different species. In acrothoracican cyprids, the most
pronounced difference on the 3rd segment is the
absence or at least extreme reduction of postaxial
Antennulary segment 4 seta 3 (ps3). In thoracican cyprids, this seta is a
in long and conspicuous simple seta, while
This segment has the same number and position of rhizocephalan male cyprids it has the form of a long
in The setae as thoracican cyprids. homology of aesthetasc (Walker, 1985; Moyse et ah, 1995). the four subterminal setae with the similarly shaped Otherwise, the third segment of acrothoracican and positioned ones in thoracican cyprids is straight- cyprids has a fairly conventional morphology. forward. There is also little doubt that the five ter- The fourth segment carries four subterminal and
in minal setae correspond to the five terminal ones in five terminal setae both the Acrothoracica and the Thoracica. One terminal seta is short the Thoracica & and this (C) very (Clare Nott, 1994), repre- in both the Thoracicaand Acrothoracica and clearly sents the cirriped ground pattern. Only the Rhizo-
both The four have fewer this and this homologous in groups. remaining cephala setae on segment,
in much longer terminal setae differ morphology is probably an apomorphic condition (Hoeg & between the two orders, so we hesitate to suggest Rybakov, 1996). However, the Acrothoracica do
The in Litho- deviate in setulation of the terminal any seta-by-seta homologies. seta lacking on any glyptes with a distended basal part and tapered apex setae, whereas the Thoracica have two setulose setae. could well correspond to seta D in thoracicans (and Grygier (1987a) made a pioneering attempt in ho- rhizocephalans). In both acrothoracicans and tho- mologizing segments and setae in antennules of racicans this seta exhibits a distinct pattern on its i ascothoracids, facetotectan cypris-y, and cirripede surface and Clare & Nott (1994) suggested that it cyprids. Further conclusions must await SEM studies is an aesthetasc. of facetotectan antennules.
Apomorphies in antennulary morphology Thoracopods
The unique structure and morphology of the cypris Few studies have focused on the cypris thoracopods, antennule involve several putative apomorphies despite their importance in the rapid swimming bouts which agrees with the claim that the Acrothoracica, during the pelagic phase of the larva. Cyprids of
Thoracica and Rhizocephala form a monophyletic Lithoglyptes and Trypetesa have a three-segmented taxon Cirripcdia. In all three orders, the antennule endopod and a two-segmented exopod just as in
of consists four segments with surprisingly similar the ground pattern for ascothoracid larvae (Turquier,
and shape function. This probably reflects func- 1967, present paper). As discussed in detail by tional the & constraints posed on antennule that func- Grygier (1987b) and commented on by Glenner Contributions to Zoology, 68 (3) - 1999 157
and Hoeg (1995), this signifies that such a segmenta- Tagmosis hindbody tion scheme characterized not only the cypris-like larva of the urthecostracan but also the true cypris According to Grygier (1983, 1987a) and Grygier
the Thecostraca of the urcirripede. Our observation on Lithoglyptes & Ohtsuka (1995) both and the also confirms Grygier’s (1987b) character matrix Maxillopoda in general have a 5-7-4 tagmosis in that the fusion in cirripedes occurred between scheme in the ground pattern. In cyprids of
the of short abdominal endopodal segments 1 and 2. The Facetotecta have Lithoglyptes presence four, a three-segmented endopod in the ground pattern, segments and an elongate telson with unsegmented but Schram (1970) and Grygier (1987b) found that furcal rami dovetails with this pattern. The ap- some facetotectans have evolved a two-segmented parently 4-segmented abdomen is plesiomorphic state by fusion between endopodal segments 2 and compared to all other cirripedes (larval or adult).
3. Obviously, the two-segmented endopods found We found no trace of a 7th thoracomere, which in
facetotectans do the unless in some cirripeds and not repre- the thecostracan ground plan carries penis,
of the here des- sent homologous states and again demonstrates how it forms part annulated region we simple counting of limb articles can lead to erro- ignate as abdomen. Unpublished SEM micrographs
in that Thora- neous conclusions as elegantly elaborated Huys reveal cyprids of some lepadomorphan
& Boxshall (1991). cica can have a three-segmented abdomen.
between A less cleaved The apparent lack of flexure endopod more or deeply telson bearing
in caudal rami constitutes segments one and two Lithoglyptes cyprids in- unsegmented a ground pat-
in It in dicates that it was these two segments that fused tern feature cirripede cypris larvae. occurs
into one in the evolution of the Thoracica (and the Acrothoracica (this study), the Rhizocephala
in and in Rhizocephala?). In the Thoracica, a faint suture (Walossek et ah, 1996) apparently also
the first segment of the endopod recalls the plesio- cyprids of lepadid Thoracica (Grygier, 1987b). In morphic three-segmented condition(Glenner et ah, contrast, Walker & Lee (1976) and Glenner& Hoeg
1995). (1995) used SEM to claim that balanomorphan
cyprids (Balanus amphitrite, Semibalanus bala-
All and have “caudalrami” inserted cirripede cyprids carry a single stout noides) two-segmented
the end of the and serrated seta on the first exopod segment ofall eight directly on posteriormost thorax
thoracopods (Glenner & Hoeg, 1995; Walossek et no visible abdomenor telson. We believe that also
rami in- ah, 1996 Fig. 14B). These setae are always shorter balanomorph cyprids have unsegmented
serted than the natatory ones on the second segment, and on a telson, but that the cleft has become
telson they undoubtedly serve in grooming both the nata- so deep that the can easily be mistaken for
tory setae and the limb bases. However, they are “basal ramal segments”. A similar error probably
if lead to describe rarely ever as large and strongly armed as in the Turquier (1967) two-segmented
acrothoracican cyprids studied here. Nothing com- “furcal rami” in cyprids of the acrothoracican Trype-
parable to these grooming setae exists in ascotho- tesa nassaroides. Support for our claim could come
racid or cypris-y larvae, so they represent another from serial sections revealing that the purported of the the “first ramal are united a slim medial many apomorphies characterizing cirripede segments” by
cyprid. connection. The urthecostracan undoubtedly had
The the 2nd caudal since find this single seta inserting on endopod unsegmented rami, we con-
segment is also present in ascothoracid larvae, dition in both the Ascothoracida, the Facetotecta,
cypris-y, and in thoracican cypris larvae. But aside and the outgroup Copepoda (Grygier, 1987b).
from SEM TEM studies this, it is premature to speculate on the ground Obviously, and of the hindbody
pattern of thoracopodal natatory setae in the in additional thoracican cyprids may provide Thecostraca. characters useful for a phylogenetic analysis. 158 G.A. Kolbasov, J.T. Haeg & A.S. Elfimov - Acrothoracican cypris larvae
Conclusion Acknowledgements
JTH and GAK their gratitude to H. Glenner, J. Olesen The data from SEM analysis presented here again express and T. Schiotte for help with SEM preparation and operation. highlight the value of larval characters in elucidat- Grants no. 11-9652 and no. 9701589 from the Danish Natural ing thecostracan and cirripede phylogeny (Grygier Science Research Council enabled JTH to finance GAK visits
1987a& Jensen ct b, 1994, 1995; al„ 1994; Elfimov, to Denmark and are gratefully acknowledged, GAK thanks the
1995; Moyse et al., 1995; Hoeg et al., 1998). The Russian Foundation for Basic Research (grant N 97-04-49803)
for supporting his work in Moscow State University. GAK also cypris larvae of the Acrothoracica exhibit similari- acknowledges Dr. D.L. Ivanov (the chief ofthe mollusc collection ties both with the Ascothoracida and the Facetotecta, of the Zoological Museum of Moscow State University) and and with the two orders. Al- remaining cirripede R.V. Egorov for an opportunity to examine the collections of
though we await a full-fledged phylogenetic analysis, the Zoological Museum and help in the species determination
of mollusc shells. ASE and GAK are finally indebted to G.N. as in Glenner et al. (1995), we will here assume Davidovich and LA. Bogdanov of the Laboratory of Electron that the similarities with ascothoracid larvae and Microscopy ofthe Biological Faculty ofMoscow State University facetotectan cypris-y represent symplesiomorphies. for help with SEM investigations,
They include: the “keel in a trough” shape of the
endo- lattice organ; three-segmented thoracopodal References pods; a five-segmented hindbody.
These plcsiomorphies do not alter the fact that
Clare AS, Nott JA. 1994. Scanning electron microscopy of the Acrothoracica have a typical cirripede cypris the fourth antennular segment of Balanus amphitrite with its numerous apomorphies compared to the amphitrite. J. Mar. Biol. Ass. U.K. 74: 967-970. thecostracan such ground as: a single pair Elfimov AS. 1986. ofthe in the pattern, Morphology carapace cypris the of frontal (horn) gland pores on carapace; very larva of Heteralepas mystacophora Newman (Cirripedia,
Thoracica) Biol. 1986(3): 30-34. [In Russian], Morya , similar four-segmented antennules with a homolo- translation in: Soviet Biol. [English J. mar. 12: 152-156] attachment the third and gous organ on segment Elfimov AS. 1995. Comparative morphology of thoracican a 4+5 setation scheme on the fourth segment; larvae: studies the Crust. Issues 10: 137-152. on carapace. the paired cement glands terminating on attachment Gibson P, Nott JA. 1971. Concerning the fourth antennular
with serrated of the cypris larva of Balanus balanoides. In: organ; thoracopods a stout, seta on segment Crisp DJ, ed. Fourth European Marine Biology Sympo- the first exopodal segment; abdomen highly short- sium. Cambridge University Press, 227-236. ened. Glenner H. in Functional ofthe press. morphology cirripede The status of other characters remains some more cypris: A comparative approach. In; Thompson MF,
eds. Barnacle uncertain or insufficiently analysed: the position Nagabhushanam R, Fouling: Ecophysiol-
and Control A.I.B.S. of the terminal in lattice the ogy Technology. Washington: pore organs; presence Glenner H, Grygicr MJ, Hoeg JT, Jensen PG, Schram of a penis rudiment; and the number and special FR. 1995. Cladistic analysis of the Cirripedia Thoracica of thoracic setae. morphology natatory (Crustacea: Thecostraca). Zool. J. Linn. Soc. 114: 365-404.
Glenner H, Hoeg JT. 1995. Scanning electron microscopy
of cypris larvae of Balanus amphitrite amphitrite (Cirri- have in this We paper proposed some phyloge- pedia: Thoracica: Balanomorpha). J. Crustacean Biot. 15: netic scenarios based on characters sets, but single 523-536. we stress that they are meant at this point more Glenner H, Hoeg JT, Klysner A, Brodin Larsen B. 1989.
Cypris ultrastructure, metamorphosis and sex in seven as mental exercises than solidly built theories. Yet familiesofparasitic barnacles (Crustacea: Cirripedia: Rhizo- those with studies such as the present one and of cephala). Acta zool. (Stockholm) 70: 229-242. Grygier (1994), Jensen et al. (1994), Moyse et al. Gotelli NJ, Spivey HR. 1992. Male parasitism and intrasexual Korn Elfimov and Walossek (1995), (1995), (1995), competition in a burrowing barnacle. Oecologia 91: 474-
480. et al. (1996) we are approaching the point where Grygier MJ. 1983. Ascothoracida and the unity ofthe Maxil- we can enlarge the thecostracan character matrix lopoda. Crust. Issues 1: 75-103. of Grygier (1987b) and Glenner et al. (1995) with Grygier MJ. 1987a. Nauplii, antennular ontogeny, and the a wealth of characters from larval new morphol- position of the Ascothoracida within the Maxillopoda. J. ogy. Crustacean Biol. 1: 87-104. Contributions to Zoology, 68 (3) - 1999 159
Grygier MJ. 1987b. New records, external and internal Korn OM. 1995. Naupliar evidence for cirripede taxonomy
anatomy, and systematic position of Hansen’s Y-larvae and phylogeny. Crust. Issues 10: 87-121.
(Crustacea: Maxillopoda: Facetotecta). Sarsia 72: 261-278. Kiihnert L. 1934. Beitrag zur Entwicklungsgeschichte von
Grygier MJ. 1994. Developmental patterns and updated hy- Alcippe lampas Hancock. Z. Morph. Okol. Tiere 29: 45-78.
potheses of homology in the antennules of Thecostracan Moysc J, Jensen PG, Hoeg JT, Al-Yahya H. 1995. Attach-
larvae Acta Zool. 75: in larvae: electron nauplius (Crustacea). (Stockholm), ment organs cypris using scanning micro-
219-234. Crust. Issues 10: 153-178. scopy.
Grygier MJ. 1995. An unusual barnacle nauplius illustrat- Newman WA. 1971. A deep-sea burrowing barnacle (Cirri-
ing several hitherto unappreciated features useful in cirri- pedia: Acrothoracica) from Bermuda. J. Zool, Land. 165:
pede systematics. Crust. Issues 10: 123-136. 423-429.
Grygier Newman WA. 1985. Motility and calcareous MJ, Newman WA. 1974. Two new deep-sea Cirripedia (Ascothora-
in and fossil Acrothoracica Cirri- parts extant (Crustacea: cica and Acrothoracica) from the Atlantic. J. Mar. Biol.
based new in pedia), primarily upon species burrowing Ass. U.K. 54: 437-456.
the coral Trans. San Soc. deep-sea Enallopsammia. Diego Newman WA. 1982. Cirripedia. In; L. G, Abele, ed. The
nat. Hist. 21: 1-22. Biology of the Crustacea I. Systematics, the Fossil Record, MJ, Ohtsuka S. 1995. New species of Synagoga Grygier and Biogeography. London, New York: Academic Press, from off Okinawa, (Crustacea: Ascothoracida) plankton 197-221.
Pubis. Japan, with a SEM study of the Seto carapace. Newman WA. 1987. Evolution of cirripedes and their major Mar. Biot. Lab. 36: 393-311. Crust. Issues 5: 3-42, groups. Hoeg JT. 1985. Cypris settlement, kentrogon formation and Newman WA. 1996. Sous-Classe des Cirripedes (Cirripedia host invasion in the parasitic barnacle Lernaeodiscus porcel- Burmeister, 1834). Super-ordres des Thoraciques et des lanae (Muller) (Crustacea: Cirripedia: Rhizocephala). Acta Acrothoraciques (Thoracica Darwin, 1854 - Acrothoracica Zool. (Stockholm) 66: 1-45. Gruvel, 1905). In: Forest J, ed. Trade de Zoologie, Tome Hneg JT. 1992. The phylogenetic position of the Rhizocephala: VIIFasc. II, Crustaces: Generalites (suite) et Systematique Are they truly barnacles?. Acta Zool. (Stockholm) 73: (I. partie). Paris: Masson, 453-540. 323-326. Nott J, Foster B. 1969. On the structure of the antennular Hoeg JT. 1995. Sex and the single cirripede: a phylogenetic attachment ofthe larva of Balanus balanoides organ cypris perspective. Crust. Issues 10: 195-206. (L.). Phil. Trans. R. Soc. Land. 256B: 115-134. Hoeg JT, Hosfcld B, Jensen PG. 1998. TEM studies of Schram TA. 1970. Marine biological investigations in the of larvae lattice organs cirripede cypris (Crustacea, Bahamas 14. Cypris y, a later developmental stage of Thecostraca, Cirripedia). Zoomorphology, 118: 195-205. Hansen. Sarsia 44: 9-24. nauplius y Hneg JT, Rybakov AV. 1996. Cypris ultrastructure in Spears T, Abele LG & Applegate MA. 1994. A phyloge- Arcturosaccus kussakini (Rhizocephala) and the homol- netic study ofcirripeds and their relatives (Crustacea Theco- of setae the fourth antennular in rhizo- ogy on segment straca). J. Crustacean Biol. 14: 641-656. cephalan and thoracican cyprids. Zool. Anz. 234: 241-251. Tomlinson JT. 1969. The burrowing barnacles (Cirripedia; Hosfcld B, Hoeg JT, Jensen PG. 1998. Ultrastructure of order Acrothoracica), Bull. U.S. Natl. Mus. 296: 1-162. for lattice organs in facetotectan cypris-y: implications Turquier Y. 1967. Le developpement larvaire de Trypetesa thecostracan phylogeny. 4th International Crustacean Con- nassaroides Turquier (Cirripede et 1998. Abstract Acrothoracique) ses gress, Amsterdam, July 20-24, volume, rapports avec celle des autres Cirripedes. Arch. Zool. Exp. Huys R, Boxshall GA. 1991. Copepod Evolution. London: Gen. 108; 33-47. Ray Society. Turquier Y. 1970. Recherchcs sur la biologie des Cirripedes Ito T, Grygier MJ. 1990. Description and complete larval III. La des femelles of Baccalaureus Acrothoraciques, metamorphose cypris development of a new species (Crusta- de Trypetesa lampas (Hancock) et de Trypetesa nassaroides cea: Ascothoracida) parasitic in a zoanthid from Tanabe Turquier. Arch. Zool. Exp. Gen. Ill: 573-627. Bay, Honshu, Japan. Zool. Sci. 7: 485-515. Y. 1971. Recherches la des Jensen PG. 1993. Ultrastructure and phylogenetic signifi- Turquier sur biologie Cirripedes
IV. La des males cance of ‘lattice organs’ in thecostracan larvae. Amer. Acrothoraciques. metamorphose cypris nassaroides et Zool. 33(5): 6A. de Trypetesa Turquier de Trypetesa lampas
Arch. Zool. Gen. 301-348. Jensen PG, Moysc J, Hoeg JT, Al-Yahya H. 1994. Com- (Hancock). Exp. 112:
SEM studies of lattice Putative Y. 1972. Contribution a la connaisance des parative organs: sensory Turquier
Zool. Gen. 113: structures on the carapace of larvae from Ascothoracida Cirripedes Acrothoraciques. Arch. Exp.
and Cirripedia (Crustacea Maxillopoda Thecostraca). Acta 499-551.
Zool. (Stockholm) 75: 125-142. Turquier Y. 1985. Cirripedes Acrothoraciques des cotes
Klcpal W, Nemcschkal HL. 1995. Cuticular structures in occidentales de la Mediterranee et de 1’Afrique du Not'd.
the males of A char- II. Weltneria zibrowii Bull. Soc. Zool. Fr. 110: Scalpellidae (Cirripedia Thoracica): n. sp.
acter analysis. Crust. Issues 10: 179-194. 169- 189. Kolbasov GA. 1996. The significance of symbiosis in the Walker G. 1985. The cypris larvae of Sacculina carcini
evolution of sessile barnacles (Cirripedia Balanoidea). Thompson (Crustacea; Cirripedia: Rhizocephala). ,/. Exp.
Arthropoda Selecta 5(1/2): 3-16. Mar. Biol. Ecol. 93: 131-145. 160 G.A. Kolbasov, J. T. Haeg & A.S. Elfimov - Acrothomcican cypris larvae
Walker Lee V. 1976. Surface and of the tenellus G, structure sense organs ment rhizocephalan cirripede Briarosaccus
of the cypris larva of Balanus balanoides by scanning (Maxillopoda: Thecostraca) reared in the laboratory; A
and transmission electron microscopy. J. Zoo/., Land. 178: scanning electron microscopy study. Hydrobiologia 328:
161-172. 9-47.
Walker G, Yule AB, Nott JA. 1987. Structure and function Wells HW, Tomlinson JT. 1966. A new burrowing bar-
of balanomorph larvae. Crust. Issues 5: 307-328. nacle from the Western Atlantic. Quart J. Florida Acad.
Walley LJ. 1969. Studies on the larval structure and meta- Sci. 29: 27-37.
morphosis of Balanus balanoides (L.). Phil. Trans. R.
Soc. Land. 256B: 237-280,
Walossck I), Hocg JT, Shirley TC. 1996. Larval develop- First draft received: I July 1998