biology and functional morphology of a new species of endolithic bryopa (bivalvia: anomalodesmata:...

Biology and functional morphology of a new species of endolithic Bryopa(Bivalvia: Anomalodesmata: Clavagelloidea) from Japan

and a comparison with fossil species of Stirpulina and other Clavagellidae

Brian Mortona

Department of Zoology, The Natural History Museum, Cromwell Road, London SW7 5BD, UK

Abstract. A new species of Clavagellidae, Bryopa aligamenta, from Okinawa, Japan, is de-scribed. The species is endolithic in living corals, with the left valve cemented to the crypt wall,as in all clavagellids. The free right valve exhibits an unusual growth pattern, with commar-ginal lines seemingly arising from the posterior valve margin and extending towards theanterior. This results from: (i) progressive anterior erosion of the umbones, probably as aconsequence of the boring process; (ii) the apparent migration posteriorly, as the umbones areeroded, of the dorso-ventral growth axis of the shell; and (iii) enhanced posterior inter-com-marginal growth. Unlike other clavagellid genera and species, however, there is no discernibleprimary ligament, at least in the adult. It is possible, however, that if a juvenile ligament werepresent (as in B. lata), it too would be lost as a consequence of antero-dorsal erosion duringboring. To retain valve alignment in the absence of a primary ligament, and possibly uponreaching an adult size, the mantle lays down alternating layers of calcium carbonate andproteinaceous periostracum onto the interior surface of the shell to thicken it, most noticeablymarginally and, especially, posteriorly. The two valves are united dorsally, therefore, by thinlayers of periostracum that probably exert a minimal opening force. B. aligamenta is, how-ever, further characterised by large adductor, pallial, and siphonal retractor muscles so thatthe entire animal is encased tightly within an internally strengthened shell within a crypt.Movement must be minimal, blood being pumped into pallial haemocoels to push openthe valves and extend the siphons. Despite a suggestion to the contrary, Bryopa is retainedin the Clavagellidae, its unusual growth processes resulting from an endolithic life stylewithin living corals.The fossil clavagellid Stirpulina bacillus, from the Pliocene/Pleistocene of Palermo, Sicily, It-aly, was, unlike Bryopa aligamenta and other clavagellids, endobenthic, with a long adven-titious tube and anterior watering pot superficially similar to species of Penicillidae, anotherfamily of the Clavagelloidea. Furthermore, as in all clavagellids only the left valve is fusedinto the fabric of the tube, the right being free within it. In all penicillids, both valves are fusedinto the fabric of their tubes. The watering pots of the fossil S. coronata, S. vicentina, andS. bacillus, moreover, are formed in a different manner to that of penicillids, by progressiveencasement of the right valve inside the tube. In penicillids, the tube is secreted in a singleevent from the general mantle surface and the incorporation of both valves into its fabric. Theconstituent genera of the Clavagellidae thus constitute an example of parallel evolution withmembers of the Penicillidae.

Additional key words: absent ligament, growth pattern, Penicillidae, tube/crypt-dwelling,

parallel evolution

Most recent authors, for example, L. A. Smith(1962a,b), Keen & L. A. Smith (1969), and B. J.

Smith (1971, 1976) considered that the Clavagello-idea D’ORBIGNY 1844 comprised but one family—the Clavagellidae. Gray (1858), however, believedthat his family the Aspergillidae comprised twosubfamilies, the Clavagellina and Penicillina.Starobogatov (1992) considered that his suborder

Invertebrate Biology 124(3): 202–219.

r 2005 American Microscopical Society, Inc.

DOI: 10.1111/j.1744-7410.2005.00020.x

aAuthor for correspondence.

E-mail: [email protected]

Clavagelloidei contained two superfamilies, the Pen-icilloidea and Clavagelloidea. Savazzi (1999: p. 231)said, ‘‘It cannot be excluded that the Clavagella andBrechites lineages represent a case of parallel evolu-tion.’’ Morton (2002a) showed that Humphreyiastrangei (A. ADAMS 1852) was essentially a cementedpenicillid, obviating the need for another of Gray’sfamilies, the Humphreyiadae. In continuing toexamine this complex taxonomy, however, and asmore species have been discovered for examination,Morton (2004a,b,c) has suggested that representa-tives of the Clavagellidae with but one valve unitedinto the fabric of an adventitious tube (Stirpulina,Dianadema) (Morton 2003) or crypt (Clavagella,Bryopa) (Morton 1984a; Savazzi 2000) are dis-tinct from those of the Penicillidae (Brechites,Humphreyia, Nipponoclava, Kendrickiana, Foegia,Penicillus) (Morton 1984b, 2002a,b, 2004a,b,c, un-publ. data) with both valves so united.

Savazzi (2000) examined shell valves and crypts ofBryopa lata (BRODERIP 1834) and concluded that thisspecies constituted a third, but un-named, clavagel-loid clade, distinct from both clavagellids and pen-icillids. This conclusion was based on the observationthat the animal somehow moved posteriorly to keeppace with a coral habitat accreting also in this direc-tion. Furthermore, in this process, the anterior valvemargins were resorbed, resulting in the loss of theumbones. Such a growth pattern, with commarginalgrowth lines seemingly arising from the posterior andextending towards the anterior, is remarkable. Spec-imens with the name B. lata obtained from Japan arenot this species and this paper describes a new speciesof endolithic Clavagellidae. Once described, the firstaim of this study was to understand and interpret thehighly unusual pattern of growth noted in B. lata andalso expressed by this new species.

Morton (2003) also studied the cemented, epi-benthic clavagellid Dianadema multangularis (TATE

1887). Species ofClavagellaLAMARCK 1818 have beenstudied by Broderip (1834, 1835), Owen (1835),Chenu (1843), Reeve (1873), Soliman (1971),Appukuttan (1974), Kilburn (1974), and Morton(1984b). The genus Clavagella has, however, beenthought to comprise a number of subgenera (Smith1971, 1976), that is, Clavagella, Bryopa GRAY 1847,and Dacosta GRAY 1858. From their own des-criptions and illustrations, it appears that Owenand Kilburn were examining Clavagella, whereasAppukuttan was studying Bryopa, as was Soliman(Savazzi 2000; this study). The type species of Dacos-ta is C. (D). australis SOWERBY 1829, which was de-scribed anatomically by Morton (1984a) and whoconsidered it did not differ in any significant way

from Clavagella (Dacosta) (OWEN 1835). Since, how-ever, Savazzi (2000) now considers Bryopa to be dis-tinct from Clavagella, at least at the subfamily level,the taxonomy of the extant Clavagellidae is clearlyconfused and the second aim of this study attempts tobring some order to it.

There are also fossil species ofClavagella (Pojeta &Sohl 1988; Jones & Nicol 1989; Stallwood 1995),Ascaulocardium (Pojeta & Sohl 1987), Stirpulina(Deshayes 1824; Forbes 1845; Dixon 1878; Sacco1901; Lucovic 1922; Savazzi 1982), and Parastirpulina(Pojeta & Johnson 1995). The only extant species ofan endobenthic clavagellid, originally described asClavagella ramosa (DUNKER 1882) but assigned tothe genus Stirpuliniola by Habe (1977), occurs in Jap-anese waters (Habe 1952). Only its tube has ever beendescribed and no known specimens are available forexamination. A third aim of this study was to try toascertain whether or not the new species of Bryopaherein described is substantially different from fossilspecies of Stirpulina, i.e., S. bacillus (BROCCHI 1814)and S. coronata (DESHAYES 1824), and, by associa-tion, Clavagella and Dianadema. This comparison,however, led to a fourth aim which was to determinewhether or not Bryopa constitutes a third clade ofwatering pot shells, in addition to the Clavagellidaeand Penicillidae, as suggested by Savazzi (2000).

Methods

Two specimens, one intact animal, the other a freeright valve plus animal only, of what had been iden-tified as Bryopa lata (BRODERIP 1834) were receivedfrom Dr Hiroshi Saito, National Science Museum,Tokyo. The two specimens had been collected fromdead (but actually living: this study) corals (Poritesand Goniastrea) at Kushi, Nago-shi, OkinawaPrefecture, Japan, in 1980.

One specimen was dissected from the right side andsubsequently, following routine histological proce-dures, sectioned transversely at 6 mm. Every 10th sec-tion was kept and alternate slides stained in eitherEhrlich’s haematoxylin and eosin, or Masson’s tri-chrome. Unfortunately, the specimens had beenpoorly fixed and only limited information could beobtained from the sections. Finally, the single rightvalve was slightly surface etched with dilute nitricacid to determine if growth lines on the outside of theshell were also present on the inner nacreous layer.Similarly, the corals onto which the left valve of thecomplete animal had been cemented were also etchedto determine its external structure.

Also examined was the holotype of Bryopa lata(Reg. no.: NHM 1950.10.16.1) and a dry specimen

Biology of a new endolithic Bryopa sp. 203

Invertebrate Biologyvol. 124, no. 3, summer 2005

(Reg. no.: NHM 20040572) of Bryopa aperta(SOWERBY, 1823) in the collections of the Departmentof Zoology, The Natural History Museum, London.Specimens of the fossils Stirpulina bacillus (BROCCHI,1814) from the Pliocene/Pleistocene of Palermo, Sic-ily, Italy, in the collections of the Sedgwick Museum,University of Cambridge (Reg. no.: C83070–3) andStirpulina coronata (DESHAYES 1824) from the Eoceneof the Bracklesham Beds, UK, in the Department ofGeology, Natural History Museum, London (PrattCollection, no registration numbers), have also beenexamined.

Results

Taxonomic account

The taxonomy of Clavagella LAMARCK 1818 sensulato, hitherto considered the sole genus of the Clava-gellidae, is confused. Keen & L. A. Smith (1969)divided Clavagella into four subgenera, that is,Clavagella, Bryopa GRAY 1847, Dacosta GRAY 1858(Gray 1858, however, considered these three to con-stitute valid genera), and Stirpulina STOLICZKA 1870.The last revision of Clavagella was by B. J. Smith(1976) who followed this subgeneric arrangementand identified the following species: C. (C.) torresiSMITH, 1885, C. (C.) multangularis (TATE 1887),C. (B.) aperta (SOWERBY 1823) (with two subspecies),C. (B.) lata (BRODERIP 1834), C. (B.) melitensis(BRODERIP 1834), C. (D.). australis (SOWERBY 1829)(with two subspecies) and C. (S.) ramosaDUNKER 1882.

Superfamily Clavagelloidea D’ORBIGNY 1843

Family Clavagellidae D’ORBIGNY 1843

Bryopa GRAY 1847

Type species: Clavagella aperta SOWERBY 1823, by

original designation

Bryopa aligamenta sp. nov.

Holotype. Specimen is a left valve attached to itsburrow wall and partly etched dorsally and a freeright valve. Tissues also preserved. Plus a second freeright valve in the same lot. National Science Muse-um, Tokyo (NSMT) Reg. No. Mo 73507 (shells alsoillustrated in Nakamine & Habe 1980: pl. 4, figs. 2,3).Diagnosis. Adult shellB20 mm in length, internal-

ly nacreous, inequivalve and somewhat inequilateral,that is, posteriorly foreshortened and anteriorly elon-gate. The left valve, which is anteriorly narrow andposteriorly enlarged and rounded, is cemented to the

wall of a coralliferous crypt that the animal inhabits.There is no obvious umbo or hinge plate dorsally.The right valve is free inside the crypt and has a nar-row hinge plate but no primary ligament and hingeteeth. Dorsally in the free right valve, there is a smallprojection that is possibly the remnant of a heavilyeroded umbo. The right valve margin is anteriorlyenlarged and smoothly rounded, whereas the poste-rior is narrow and blunt. The valves gape both ante-riorly and posteriorly, and their margins are nowherecongruent except dorsally. The shell valves are uniteddorsally by thin sheets of periostracum that alternatewith layers of calcium carbonate. Such internally laiddown layers, however, are also secreted over the en-tire inner surfaces of the valves thereby thickeningand presumably strengthening the shell. The crypthas a posterior siphonal canal that is also lined withcalcium carbonate, but without a tubular extensionbeyond the coral surface as in Bryopa aperta. Thereare no anterior tubules leading into the crypt, as thereare in species of Clavagella (Morton 1984a).

Large, dorsally located, anterior and posterior ad-ductor muscles, the latter slightly larger than theformer; no obvious pedal retractor muscles. Thereis a thick pallial line with a deep, also thick, pallialsinus. The absence of a ligament and interior thick-ening of the shell valves separates Bryopa aligamentafrom all other extant species of the genus.

Etymology. Referring to the absence of a ligament(L. ligamentum).

Distribution. Known only from the type locality ofKushi, Nago-shi, Okinawa Prefecture, Japan.

Comparison with other genera and species. The typespecies of Clavagella sensu stricto is C. echinata(LAMARCK 1818) an Eocene fossil from the ParisBasin and from which a large number of closely sim-ilar species have been described. This fossil, however,has all the characters of extant species of Clavagella,i.e., the left valve is fused to a crypt, a free right valvewith usual growth lines, an internal amphidetic liga-ment, a simple unadorned posterior siphonal tube,and tubules arising from the anterior and ventral re-gions of the crypt (Morton 1984a). Similarly, Morton(1984a) could not separate Dacosta from Clavagellaon any basic character. Moreover, since the subgenuswas established to accommodate only the Australianspecies, C. (D.) australis (studied by Morton), it wassuggested that Dacosta be abandoned.

Morton (2003) demonstrated that Clavagella (C.)torresi and C. (C.) multangularis were small, epi-benthic, cemented species with tubules which arosefrom the crypt dorsally (like a crown) and overlaidthe left valve and reassigned them to a new genusDianadema (Morton, 2003).

204 Morton


Species of Stirpulina can be easily identified andseparated from all other clavagellids because they areendobenthic, occupying a long, apically frilled, orruffled, adventitious tube with an anterior wateringpot. The watering pot is superficially reminiscent ofthose possessed by representatives of the similarlyendobenthic Penicillidae but (as this study will show)has a different structure. Stirpuliniola KURODA &HABE 1971 was erected to accommodate the onlyextant (Japanese) species—S. ramosa (DUNKER

1882)—thereby suggesting that Stirpulina should berestricted to fossil taxa. Since, however, S. ramosahas never been examined except externally, the va-lidity of this suggestion awaits confirmation.

Smith (1976) considered there to be three extantspecies of Bryopa, that is, B. lata, B. aperta, and B.melitensis. Previously, however, Gray (1858) had syn-onymised B. melitensis (illustrated in Reeve 1873: pl.II, species 5) with B. aperta (illustrated in Reeve 1873:pl. I, species 2). The siphonal tube of B. aperta is fril-led, whereas that of B. lata is simple. The holotype ofB. lata, to which the specimens herein described wereinitially assigned, is in the collections of the Depart-ment of Zoology, The Natural History Museum,London. The species was also illustrated by Brode-rip (1835: pl. 30, figs. 8–16). B. lata has further beendescribed and discussed in detail by Savazzi (2000)who identified key features as follows: ‘‘the inner sur-face of the left valve is a raised platform carryingcoarse growth lines,’’ ‘‘the right valveymuch short-er than the left,’’ ‘‘posterior adductor scar from fourto eight times larger than the anterior,’’ ‘‘no umbo’’(p. 315), and a ‘‘strongly prosodetic’’ ligament(p. 316). The species herein described does not findaccord with these characters of B. lata.

In addition to identifying a new species of Bryopa,therefore, this study further suggests that the Cla-vagellidae comprises the following extant genera:Clavagella Dacosta, Dianadema, Bryopa, and Stir-pulina (or Stirpuliniola, see above). All have fossilrepresentatives, but other extinct, North American,genera areAscaulocardium (POJETA & SOHL 1987) andParastirpulina (POJETA & JOHNSON 1995).

Bryopa aligamenta

Crypt and shell.Members of B. aligamenta are end-olithic in living corals, whereas the shells of B. latadescribed by Savazzi (2000) were found in dead cor-als. Presumably, however, both could have once beenalive simultaneously. The borehole occupied by indi-viduals of B. aligamenta has been termed a crypt(Savazzi 1982). Juveniles of the similarly endolithicB. lata are free living (Palazzi & Villari 2000: p. 27)

and described as ‘‘very thin, very flat, very brittle,shiny and nacreous inside.’’ The right valve of a ju-venile of B. lata is illustrated in Fig. 1a. The shell isanteriorly foreshortened and posteriorly elongate,giving it a heteromyarian form. From the umbo ariseradiating lines of striae and periostracal spinules, asfirst described for Lyonsia hyalina by Prezant (1979)and subsequently for many clavagellids, e.g., Clavag-ella australis (Morton 1984a) and penicillids (Morton1984b, 2002a,b, 2004b). These are illustrated for B.lata by Palazzi & Villari (2000: figs. 130–132). Thehinge area of a juvenile of B. lata (Fig. 1b) has anobvious prodissoconch (PR) which is B170 mm inlength and a hinge plate (HP) that possibly possessesa single hinge tooth (HT?). From the umbo arises anexternal opisthodetic ligament (PRL).

After an unknown period of freedom, the juvenileof B. lata either nestles in or bores into its adult hab-itat and attaches to its crypt by the left valve. This ispossibly also the case in B. aligamenta and the leftvalve is, like all clavagellids, similarly cemented,whereas the right remains free (Fig. 2a,b). Tayloret al. (1973) showed that the shell valves ofClavagella(5B.) aperta comprise a thin simple prismatic outerlayer with a sheet nacre inner layer. Externally, theshell is covered with a calcareous concretion that is inplaces eroded to reveal the nacreous layer beneath.This concretion is not a thin, simple prismatic layerand is not present (as will be described) on the outersurface of the left valve. It is thus laid over the outersurface of the right valve secondarily and its growthlines match those of the nacreous layer beneath.

The shell of B. aligamenta is also notable in that,as noted by Savazzi (2000) for B. lata, its externalgrowth lines (Fig. 2a) appear to arise from the pos-terior end of the free right valve and extend towardsthe anterior. This is a remarkable growth pattern thatwas interpreted by Savazzi (2000) and will be dis-cussed herein. In other respects, the cemented leftvalve margin is anteriorly narrow and posteriorly in-flated whereas, conversely, the free right valve marginis posteriorly blunt and narrow, and anteriorly en-larged and rounded. Internally, on the right valveonly (Fig. 2b), there is a dorsal hinge plate (HP) withno hinge teeth. Savazzi (2000) considered that B. latadoes not possess umbones, these being progressivelylost as the anterior regions of the shell are eroded.Despite the growth lines radiating from the posteriorvalve margin, Savazzi (2000) considered that this endof the valve was also enlarged, as the animal attempt-ed to keep pace with an accreting coral surface. Asin B. lata, (Savazzi 2000: figs. 4b,d, 5b), the free rightvalve of B. aligamenta possesses a small dorsal pro-jection that looks like the heavily eroded remnant of



an umbo (Figs. 2b, 4, EU). The adductor musclescars (AA, PA) are large, that of the posterior beingslightly bigger. The pallial sinus (PS) is narrow butextends further anteriorly than the notional middorso-ventral growth axis of the shell. Ventrally,the pallial line (PL) is thick and deeply recessed in-side the shell valves.

The irregular margin of the attached left valve(Fig. 2c) only approximates that of the right, beingmore truncated anteriorly and more rounded poste-riorly. The two valves thus have a poor marginal un-ion, and they gape both anteriorly and posteriorly.The outline of the valve is demarcated from the cryptwall (C) by a fringe of periostracum (PE). Posterior-ly, the crypt is formed into a siphonal canal (SC) thatis lined with layers of calcium carbonate. The umboand hinge plate of the left valve are so eroded as to beindistinguishable, but the dorsal region is indented atapproximately the position of the small projection(possibly an umbonal remnant) on the right valve.The locations of the internal adductor muscle scars(AA, PA), and pallial line (PL) and sinus (PS), are,however, positioned as in the right valve.

The left valve is cemented to the borehole wall. Asillustrated in Fig. 3, the coral skeleton into which the

animal has bored and to which the left valve is ce-mented has been etched, using dilute nitric acid,down to the outer surface of the shell. Unfortunate-ly, small areas of the dorsal region of the valve werealso dissolved (ET) in the etching process. Notwith-standing, the bases of the coral polyp skeletons (CPS)are attached to the nacreous shell that comprises lay-ers (NL), as in the right valve. Unlike the right valveof B. lata (Taylor et al. 1973) and that of B. aliga-menta, the left valve of the latter is not covered by asimple, prismatic outer layer (or if it is, it must bevery thin) nor a thick layer of calcareous material. B.aligamenta thus cements its left valve directly ontothe bases of the living coral skeletons that it hasbored into, and lays down extra layers of nacreinternally.

Yonge & Morton (1980) describe the ligament ofvarious representatives of the Anomalodesmata.There is a wide variety of form, from external to in-ternal and from opisthodetic to sunken and support-ed by chondrophores. Often there is a lithodesma.The ligament of Clavagella australis is internallysunken and supported by chondrophores (Morton1984a). Appukuttan (1974: p. 20) describes the liga-ment of B. lata as ‘‘prominent’’ whereas Savazzi

Fig. 1. Bryopa lata. Juvenile. a.

External view of the right valve.

b. Internal view of the right hinge

plate of specimen in ‘‘a’’ (redrawn

after Palazzi & Villari, 2000: figs.

126, 127, respectively). For ab-

breviations see Appendix.

206 Morton


(2000, p. 315) describes the ligament of the same spe-cies as prosodetic and ‘‘inserted onto a platform pro-jecting from the left valve across the medial plane’’and ‘‘located slightly anteriorly to the centre of thebody cavity.’’ However, the same author (also p. 315)suggests that the ‘‘hinge platform is too poorly dif-ferentiated from the rest of the shell to be character-ized as a ligamental nymph.’’ This is not so, however,because, as illustrated for the juvenile of this speciesby Palazzi & Villari (2000), the ligament is externaland opisthodetic (Fig. 1b, PRL).

The dorsal region of the shell and the hinge plate ofthe right valve of B. aligamenta (Fig. 4) is without aprimary ligament, but it is unknown if this is lost withage or simply not present. The approximate positionthat might be occupied by a ligament, however, in-stead comprises alternating layers of calcium carbon-ate and proteinaceous periostracum, presumably laiddown by the mantle beneath, as will be discussed.This area of the hinge plate is illustrated in Fig. 5a,b.The small dorsal projection is identified in Fig. 5a byan arrow and the vertical prisms, 500–750 mm tall, of

Fig. 2. Bryopa aligamenta. a.

External view of the right valve.

b. Internal view of right valve. c.

Internal view of left valve. For

abbreviations see Appendix.



the layers of calcium carbonate interleaved by theperiostracal bands are illustrated in Fig. 5b. The an-terior (Fig. 6a) and posterior (Fig. 6b) right valvemargins of B. aligamenta are also illustrated as SEMphotographs. In both cases they again comprise al-ternating layers of calcium carbonate and per-iostracum confirming that, as with the hinge plate,the mantle secretes such layers internally so that thevalves become progressively thicker and, thus, theoccupiable space between them less. This explainswhy the internal tissues of B. lata fit so tightly be-tween the valves.

B. aligamenta has a short, unornamented siphonalcanal that extends only a little beyond the substra-tum. That of B. aperta is more complicated (Fig. 7).In side view (Fig. 7a), the posterior end of the canalcomprises three pleated ruffles, i.e., it has been ex-tended at least twice. It is unknown whether suchpleated ruffles, typical of species of Brechites, Nipp-onoclava (Morton 2002b: fig. 4; 2004a, figs. 1, 2), andStirpulina bacillus (Savazzi 1990: fig. 3e), are eitherrepair or growth increments, possibly both. In thecase of this specimen of B. aperta, however, in theabsence of breaks, they seem to represent posteriorgrowth extensions. The aperture to the siphonal tubeis flared (Fig. 7b).General anatomy. Because of the poor state of pres-

ervation of the specimens of B. aligamenta herein de-

scribed, only a general description of the organs ofthe mantle cavity (Fig. 8) can be made. The most ob-vious feature of the anatomy, however, is the exten-sive muscularisation. The siphons (IS, ES) are thickand muscular and, in the preserved specimens exam-ined, deeply retracted between the shell valves. Thesiphonal and pallial retractor muscles at the mantlemargin (MM) are large, as are the anterior (AA) andposterior (PA) adductor muscles. As in B. lata, theredo not appear to be pedal retractor muscles and thefoot (F) is tiny as is the pedal gape (PG) (Appukuttan1974). Because of the extensive muscularisation,space inside the mantle cavity is limited and thepaired ctenidia are reduced. The outer demibranch(OD) in particular is posteriorly foreshortened rela-tive to the inner (ID), which is also dorso-ventrallyshort. The labial palps (ILP, OLP) are relatively longand thin.

The pericardium (P) lies beneath the hinge plateand contains a heart (HE) that comprises a singleventricle, which surrounds the rectum (R). Furtherposteriorly, this also penetrates the paired kidneys.Histological sections of the visceral mass were of toopoor a quality for further description.Siphons. The siphons of B. aligamenta, when

seen in transverse section (Fig. 9a), have thick(B1-mm) walls and are covered by a periostracumthat, as in all anomalodesmatans (Harper et al. 2000),

Fig. 4. Bryopa aligamenta. An

internal view of the hinge plate

of the right shell valve. For


Fig. 3. Bryopa aligamenta. The

external surface of the antero-

dorsal region of the left shell valve

after the coral skeletons to which it

was cemented have been etched off

using nitric acid. For abbreviations

see Appendix. Note the nacreous

layers (NL) and the absence of an

outer prismatic layer to the valve.

208 Morton


is two-layered. The inner layer (PE [IL]) stains bluefor mucus in Masson’s trichrome, the outer layer (PE[OL]) red. The outer layer is also fibrous, but sandgrains and other detritus do not attach to it, probably

because, as described for Nipponoclava gigantea(Morton 2004a), there are no radial mantle glands(Prezant 1979b) present in the siphons and whichproduce the glue that sticks such material to them.Red-staining (in Masson’s trichrome) sub-epithelialsiphon glands (SG) dot the internal surface of thesiphons. The siphons also possess 24 siphonal nerves(SN), 13 around the exhalant (ES) and 11 around theinhalant (IS) siphons. These nerves extend up to thesiphonal papillae and are thus characteristic of eachspecies of clavagelloid (Morton 2004c and referencestherein).

In greater detail (Fig. 9b), the siphonal wall ishighly muscular and comprises extensive longitudi-nal muscles (LM) formed into blocks by transversemuscle fibres (TM) connecting inner (IE) and outer(OE) epithelia and by two layers of circular muscles.The inner layer (CM [I]) extends around each siphonand criss-crosses in the inter-siphonal septum; theouter layer (CM [O]) encircles both siphons. Thereare only small haemocoelomic spaces, but the exten-

Fig. 5. Bryopa aligamenta. SEM photomicrographs. a.

Hinge plate of the right shell valve. b. Detail of the

alternating layers of calcium carbonate prisms and

proteinaceous periostracum. Arrow indicates a small

dorsal projection that is possibly the remnant of a heavily

eroded umbo.

Fig. 6. Bryopa aligamenta. SEM photomicrographs. a.

Anterior shell valve margin. b. Posterior right shell valve

margin.

Fig. 7. Bryopa aperta. The posterior end of the adventitious

tube. a. Right lateral view. b. Posterior view.



sive muscularization of the siphons is responsible fortheir deep retraction between the shell valves, asdescribed for the penicillid Nipponoclava gigantea(Morton 2004a). In contrast, the weakly muscularsiphons of Kendrickiana veitchi can only be retracteda short way down the adventitious tube (Morton2004b).Mantle margin. Yonge & Morton (1980) describe

the complex disposition of the epithelia of the dorsalpallial crest in a variety of anomalodesmatans; theseepithelia are responsible for producing the diversearray of ligamental structures seen in the many rep-resentatives of the class. In the case of B. aligamenta,the dorsal region of the mantle is exceedingly simple(Fig. 10). Left and right ridges define the hinge plateand, centrally, an epithelium corresponding to thepallial crest (PC) must be responsible for the secre-

tion of the alternating layers of calcium carbonateand proteinaceous periostracum. The mantle is at-tached to the shell by suspensory muscles (SM), butthese are not distinct muscular units as described forthe penicillid Kendrickiana veitchi (Morton 2004b),but part of the more general pallial retractor musclesystem. Beneath the pallial crest is a haemocoel (H)that, with the pumping of blood into it, ensures thesecretory tissues are adpressed against the hingeplate.

In transverse section, the ventral mantle margin ofB. aligamenta (Fig. 11) is thick and muscular. Poste-rior to the pedal gape (Fig. 11a), the left and rightmantle lobes are extensively fused by the inner, mid-dle, and inner surfaces of the outer mantle folds. Thisis type C fusion (Yonge 1982), so the whole ofthe mantle is here covered in periostracum (PE)

Fig. 8. Bryopa aligamenta. The

organs of the mantle cavity as

seen from the right side. For


Fig. 9. Bryopa aligamenta. Trans-

verse sections. a. Siphons. b. Part

of siphonal wall. For abbreviations

see Appendix.

210 Morton


that arises from small periostracal grooves laterally.There are large pallial retractor muscles (PRM) andlongitudinal muscle blocks (LM) that are part of the

siphonal retractor muscle system. There are alsosmall haemocoelomic spaces (H).

Mantle fusions cease at the pedal gape (Fig. 11b,PG) of B. aligamenta, but middle folds are not obvi-ous and the gape itself is formed by the inner mantlefolds (IMF). These possess, on their inner surfaces,blue-staining (in Masson’s trichrome) subepithelialmucous glands (MG) that presumably assist in thebinding up of unwanted material in the mantle cavityfor expulsion as pseudofaeces. The periostracum(PE) arises from lateral periostracal grooves. Heretoo, the pallial retractor muscles (PRM) are large;there are blocks of longitudinal muscles (LM), but noobvious haemocoels.

Stirpulina bacillus and S. coronata

Shell and adventitious tube. The shell and adventi-tious tube of the fossil Stirpulina bacillus from thePliocene/Pleistocene of Palermo, Sicily (Sedgwick

Fig. 11. Bryopa aligamenta.

Transverse sections. a. Ventral

mantle margin posterior to the

pedal gape. b. Ventral mantle

margin through the pedal gape.

For abbreviations see Appendix.

Fig. 10. Bryopa aligamenta. A transverse section through

the dorsal mantle. For abbreviations see Appendix.



Museum Reg. no. C 83071), is illustrated from theleft side in Fig. 12a. The left shell valve that is incor-porated into the fabric of the adventitious tube is rel-atively large, B30 mm in length, and approximatelyisomyarian. Anterior to it is the watering pot, com-prising a fringe of tubules that in life would open intothe mantle cavity. Posteriorly, the tube is greatly ex-tended and the animal’s life position would be verti-cally embedded in sediments, i.e., it was endobenthic.The adventitious tube is B27 cm in overall length,slightly curved, and inflated ventrally beneath theshell.

The posterior end of a second tube of Stirpulinabacillus (Sedgwick Collection Reg. no.: C 83072) isillustrated from the right side in Fig. 12b. No valve isvisible because it is enclosed within the adventitioustube. The tubules of the watering pot of this specimenare broken. But, on this side can be distinguished a‘‘pleat’’ that curves upwards from the watering pot.The possibly near-intact watering pot of a specimenof S. coronata (Pratt Collection, Natural HistoryMuseum, London: no registration number) is illus-trated in Fig. 13 from the anterior aspect. The tubulesare long and seem to branch dichotomously. Of mostinterest, however, is that the circlet of watering pottubules is not complete, but folded around a ‘‘pleat’’on the right side. The lot from which this specimenwas chosen contains numerous watering pots andthey all have the same structure, so that what is de-scribed above is not an artefact. Such a watering potstructure is fundamentally different from those ofrepresentatives of the Penicillidae (Morton 1984b,2002a,b, 2004a,b,c, unpubl. data).

Discussion

Species of Clavagella and Bryopa have been stud-ied in more recent times by Soliman (1971),Appukuttan (1974), Kilburn (1974), and Morton(1984a), although Savazzi (2000) was the first to try

to interpret the unusual shell morphology of thelatter genus and concluded that it was a borer. Sucha process envisaged, if the animal was to keep pace interms of growth posteriorly with an accreting habitat,the shell becoming elongated in an anterior directionand the umbo, hinge, unusually prosodetic ligament,and body sliding forwards too. In this process, theumbones and associated structures are progressivelydissolved and possibly resorbed. Eventually, as ante-

Fig. 12. Stirpulina bacillus. Adven-

titious tube and shell. a. Left side.

b. Watering pot as seen from the

right side.

Fig. 13. Stirpulina coronata. The watering pot as seen from

the anterior aspect.

212 Morton


rior growth slows, there is additional growth poste-riorly, creating a shell of unusual structure withgrowth lines seemingly arising from the posteriorvalve margin, not the umbones, as in a ‘‘typical’’bivalve.

Growth of the Bryopa shell

There are a number of problems with Savazzi’s in-terpretation of the shell of B. lata (and that of B.aligamenta). The first is that ‘‘None of the availablespecimens of B. lata shows overgrowth by the coralaround the siphonal opening of the crypt. This sug-gests boring of a dead substrate’’ (Savazzi 2000:p. 314), so that there is no stimulus for the animalto keep pace posteriorly with an accreting habitat.Individuals of B. aligamenta do, however, bore intoliving corals (this study). Second, Savazzi (2000:

p. 315) suggests, ‘‘the adult Bryopa has no umbo.’’The juveniles of B. aligamenta do, however, possessan umbo (Fig. 1b), and in the adult a small dorsalprojection in the right valve only is possibly the re-mains of an, albeit heavily eroded, umbo. Third,Appukuttan (1974: p. 20), also referring to B. lata,states, ‘‘a prominent ligament is present.’’ Savazzi(2000), however, asserts, ‘‘the ligament of B. lata isstrongly prosodetic with reference to the umbones’’(p. 316). This would not only be highly unusual for abivalve, but is also not so: the juvenile of B. lata hasan external, opisthodetic ligament.

This study suggests that in B. aligamenta a liga-ment was either never present or has, more likely,been lost during the process of growth and chemicalboring. Despite the lack of a primary ligament, how-ever, the two valves maintain connection dorsally bylayers of periostracum that Yonge (1976) termed a

Fig. 14. Patterns of commarginal growth. a. An approximately isomyarian bivalve, Circe. b. The posteriorly elongated

borer, Barnea. c. The anteriorly elongated burrower, Donax. d. Bryopa aligamenta, illustrated as a succession of

hypothetical ontogenetic growth stages (i–v). For abbreviations see Appendix; for an explanation see Discussion.



‘‘secondary ligament.’’ As argued by Yonge & Mor-ton (1980), however, such a periostracal ‘ligament’probably has few elastic properties and is thereforeprimarily concerned with valve alignment. This isborne out by the fact that in the specimens exam-ined, when adductor and mantle margin connectionwas cut at the points of their attachments to the rightvalve, the valves did not spring apart as those of anyother bivalve with a primary ligament would, but re-mained apposed. It has, moreover, herein beenshown that the adult shell is added to internally, byalternating layers of calcium carbonate and per-iostracum secreted by the mantle beneath. That is,the space between the valves occupied by the body ofthe animal actually decreases with age, and the valvesprobably thereby become progressively even less ca-pable of parting. This suggests that B. aligamenta,and possibly B. lata, represents an extreme exampleof adaptation to an endolithic life style: i.e., it inter-nally strengthens its shell and the outer surface of theright valve, and is probably capable of only limitedmovement even though it has relatively huge musclesto shut the shell, retract the siphons, and seal themantle cavity ventrally. Body expansion, as in manyclavagelloids (e.g., the penicillid Kendrickiana veitchi,Morton [2004b: fig. 18]), is probably by hydraulicmeans, that is, by the pumping of blood into pallialhaemocoels. Such adaptations to a boring life styleare also seen in other bivalves, e.g., the Teredinidaewhere there is also virtual loss of the ligament(Turner 1966).

Savazzi (2000) proposed a mechanism, as notedabove, to describe the unusual external architectureof the right valve of B. lata, that is, commarginalgrowth lines apparently arising from the posteriorend of the shell and extending towards the anterior.This explanation is, however, partially wrong princi-pally because, as described above, there is an umbo-nal remnant and a hinge plate. There is, however, analternative explanation to that of Savazzi’s and this isillustrated in Fig. 14. In the Bivalvia, growth in size istypically at the shell margin, resulting in the sequen-tial production on each valve of commarginal growthlines. In an equilateral, isomyarian bivalve, e.g.,Circespp. (Fig. 14a), such lines radiate out equilaterallyfrom the umbones about the dorso-ventral growthaxis of the shell (D-V). In an inequilateral bivalve,such as the posteriorly elongate borer Barnea (Fig.14b), growth ceases to be radially uniform aboutthe dorso-ventral axis, that now extends posteriorly,and the distances between successive commarginalgrowth lines become greater on the posterior slopeand restricted anteriorly. The opposite of this is seenin species of rapidly burrowingDonax (Fig. 14c), i.e.,

the dorso-ventral growth axis of the shell extends an-teriorly and hence the anterior slope of the shell be-comes larger through enhanced inter-commarginalgrowth in this direction. Such variations in the pat-terns of growth demonstrated by the many represent-atives of the Bivalvia create the order’s diversity;B. aligamenta adds to this.

Brypoa aligamenta has a similar shell form (rightvalve) to B. lata and to an unidentified species ofClavagella (Bryopa) from the Red Sea described bySoliman (1971: pl. 1a). The explanation for the un-usual shell ofB. aligamenta given below and illustratedin Fig. 14d may thus also apply to these species. Es-sentially, as suggested by Savazzi (2000) for B. lata,there is erosion of the antero-dorsal regions of theshell as the animal (chemically) etches out its burrowanteriorly, so that the juvenile primary ligament isprogressively lost. Importantly, however, so too isthe umbo which, as the focal point of valve union andwhose position determines the dorso-ventral growthaxis of the shell, appears to migrate posteriorly (as theumbones are progressively etched backwards). Thecommarginal growth lines thus appear to arise on theposterior slope of the shell and to extendtowards the anterior. In addition to the apparentposterior ‘‘migration’’ of the umbones, there is pro-portionally greater inter-commarginal growth of theposterior slope of the shell valve. This means that theposterior slope expands faster relative to the anterior,enhancing the effect created by the posteriorlymigrating growth axis. The shell shapes in B. lataand B. aligamenta thus change ontogenetically, froma juvenile free-living stage (Palazzi & Villari 2000) tothe adult (Fig. 14d: i–v).

It is interesting, again contrary to the views of Sa-vazzi (2000), that the growth form of the shell, ex-pressed best in the right valve, has not influenced theorientation of the animal within it. That is, the posi-tions of the remnant umbo and the hinge plate in thefree right valve are still dorsal and the body tissues,including the main adductor musculature, have notbeen affected by the changes in shell form. A similarsituation is also seen in the coiled and similarly ce-mented anomalodesmatan Cleidothaerus maorianusFINLAY 1827. In this bivalve, the form of the body(Morton 1974) is uninfluenced by the extreme coilingof the shell that results, for example, in the litho-desma growing around the ligament through 43601(Yonge & Morton 1980).

Life history of Bryopa

With the above interpretation available, it is pos-sible to further try to interpret the life history phases

214 Morton


in the pattern of growth expressed in B. aligamenta.Assuming that the life history of B. aligamenta issimilar to that of B. lata, then the pattern of growthcan be described in terms of three phases, as follows.Phase I. Each post-settlement individual of B. alig-

amenta commences life with ‘‘the appearance ofThracia or Lyonsia’’ (quoted from Fischer 1887 byPalazzi & Villari 2000), as a free-living juvenile that isfurther described by Palazzi & Villari as thin, flat,brittle, shiny, and internally nacreous (Fig. 14d: i,ii).This juvenile presumably now finds a crevice in acoral head to lodge itself into and commence boring.To achieve this, it presumably has mechanisms toprotect itself against the coral’s nematocysts, as inspecies of coral-boring Lithophaga (Morton & Scott1980).Phase II. Once a site for adult residence is identi-

fied, a borehole is established by an adult of B. alig-amenta and is presumably enlarged chemically in adownward direction, that is anteriorly, since there areno physical attributes of the shell that could effectmechanical boring. During this active boring phase(Fig. 14d: iii,iv), the shell architecture is progressivelymodified as the bivalve bores deeper into its substra-tum; the ligament, umbo, and the antero-dorsal mar-gin of the shell are eroded and the dorso-ventralgrowth axis of the shell appears to migrate posteri-orly. Eroded material is possibly redistributed overthe right valve to strengthen it externally and to formthe siphonal canal, as in species of coral-boringLithophaga (Morton & Scott 1980). It is not, howev-er, laid over the surface of the left valve, suggestingthat this is at all times firmly adpressed against theburrow wall and to which it becomes cemented, pos-sibly when the boring process slows as the animalapproaches maturity.Phase III. By the time boring ceases, the dorso-

ventral growth axis of the shell of B. aligamenta has

moved to a posterior position, and now the shellvalves are further strengthened internally by the pro-duction of alternating layers of calcium carbonateand proteinaceous periostracum (Fig. 14d: v). Thecalcareous layers are obvious anteriorly but especial-ly so posteriorly, as the animal now further protectsitself in this direction, for example, from surface-rov-ing predatory gastropods (Morton 1990). The layersof periostracum serve as a ‘‘secondary ligament’’(Yonge 1976) to keep the valves aligned in the ab-sence (probably loss) of a primary ligament—in thelatter case due to anterior-dorsal erosion—and func-tion as a simple hinge. This allows the valves to partwithin the narrow, protective, confines of the crypt,probably by adjustments to the haemocoelomic to-nus of the various body organs. More calcareous ma-terial is probably also deposited posteriorly, so thatthis vulnerable end of the shell fits closely up againstthe similarly lined and strengthened siphonal tube.

Formation of Stirpulina tube and watering pot

Figure 15 illustrates how the right shell valve ofStirpulina comes to be encased within its adventitioustube (after Savazzi 1982). The tube is formed first,with the left valve united into its fabric. Folds ofmantle tissue secrete calcium carbonate at their lead-ing edges (Fig. 15a) and gradually form into 5 units(Fig. 15b) that eventually coalesce, but leave a pleatextending from the also enlarged ‘‘watering pot’’ tu-bules (Fig. 15c). Such a process mirrors the situationdescribed for S. coronata in Fig. 12b and, thus, even-tually creates a watering pot that is not a symmetricaldisc, but is O-shaped (Fig. 13). Harper & Morton(2004) describe how the adventitious tube of Bre-chites vaginiferus is formed. The mechanism is whollydifferent from that described for Stirpulina. The tubeand watering pot are secreted, but from all over the

Fig. 15. Stirpulina vicentina.

Reconstruction of the growth

processes of the anterior portion

of the crypt (redrawn after

Savazzi 1982).



surface of the mantle, such that the produced secre-tions unite both valves into its final structure; thewatering pot, when seen from the anterior and asdescribed for Nipponoclava gigantea (Morton 2004a:fig. 3b), is not folded but approximately bilaterallysymmetrical.

Genera of Clavagellidae—a comparison

Savazzi (2000) suggests that the unusual featuresof members of B. lata made it a candidate for desig-nation as a third clavagelloid clade. I do not concurwith this view. As described in this paper, B. aliga-menta and B. lata only demonstrate, albeit complexand extreme, adaptations to an endolithic lifestyle,comparable with the similarly endolithic Clavagellaaustralis (Morton 1984a). Notwithstanding, the viewsof Savazzi (2000) regarding the taxonomy of theClavagelloidea find accord with my own (Morton2004a,b,c), that is, the superfamily comprises twoother clades—the families Clavagellidae and Pen-icillidae.

Table 1 provides a comparison of the 4 currentlyrecognised extant genera of the Clavagellidae. Anycomparison with Stirpulina is hampered by a lack ofinformation on the genus, the only living species,S. ramosa, never having been studied anatomically.There is clearly a range in lifestyle, from the end-obenthic Stirpulina (Savazzi 1982), to the tiny, ce-mented, epibenthic Dianadema (Morton 2003) and

the endolithic, either Clavagella (Dacosta) (nestling)or Bryopa (boring) (Morton 1984a; Savazzi 2000).All are united by the fact that only the left valve isincorporated into the fabric of either the crypt or ad-ventitious tube, but it is probable that ligament formis also related to lifestyle. Both Clavagella and Di-anadema possess calcareous spinules on their shells,particularly posteriorly, as has been reported for anumber of anomalodesmatans (Harper et al. 2000),especially the Lyonsiidae (Prezant 1979b).

No clavagellid possesses a pedal disc, and it isimportant to note that in them all, the pedal retrac-tor muscles are either vestigial (Dacosta andDianadema) or absent (Bryopa), and the foot is alsoalways small. There is, however, a pedal gape in rep-resentatives of all genera except Stirpulina (Mortonin prep. b) and, similarly, anterior tubules are presentin all genera except Bryopa. None of the genera pos-sesses a fourth pallial aperture, but radial mantleglands are present in the siphons of Dacosta, consist-ent with the presence of sand grains and other detri-tus adhering to the siphonal tips, probably tocamouflage them, in Bryopa and other clavagellidssuch as Dianadema, and the penicillids Brechites,Kendrickiana, Foegia, and Penicillus (Morton1984b, 2002b, 2003, 2004b,c, unpubl. data). Anatom-ically, all representatives are similar, as in, for exam-ple, the degree of mantle fusion (type C; Yonge1982), two-layered periostracum, and a ctenidial cil-iation of type E (Atkins 1937). These latter two

Table 1. A comparison of shell and body characters in genera of the Clavagellidae (after various authors: see text).

Dacosta Bryopa Stirpulina Dianadema

Life habit Epilithic: boring/

nestling

Epilithic: boring/

nestling

Endobenthic Epibenthic;

cemented

Left valve Cemented to

crypt wall

Cemented to

crypt wall

Incorporated

into tube

Incorporated

into tube

Right valve Free Free Free Free

Ligament Internal/

amphidetic

External/

opisthodetic;

absent/

lost in adult

Unknown Internal/

opisthodetic

Internal shell layer Nacreous Nacreous Unknown Nacreous

Outer shell layer Prismatic Prismatic Unknown Prismatic

External shell spinules Present Unknown Unknown Present

Anterior tubules Present Absent Present Present

Pedal disc Absent Absent Unknown Absent

Adductor muscles Present Present Present Present

Pedal retractor muscles Vestigial Absent ? Unknown Vestigial

Fourth pallial aperture Absent Absent ? Unknown Absent

Radial mantle glands Present Absent ? Unknown Present

Mantle fusion Type C Type C ? Unknown Type C

Ctenidial type Type E Type E ? Unknown Type E

216 Morton


characters, however, are typical of most anoma-lodesmatans (Harper et al. 2000).

With the information described above, concerninghow the adventitious tube and watering pot of Stir-pulina are formed in a fundamentally different man-ner to those of Brechites (Harper & Morton 2004), itseems highly likely that suites of genera allied to thesetwo constitute different family level lineages, i.e., theClavagellidae and Penicillidae. The shells of all rep-resentatives of both families, however, including B.lata, resemble those of lyonsiid anomalodesmatans(Palazzi & Villari 2000), a suggestion substantiatedby genetic determination of a close affinity, at leastbetween Lyonsia norwegica and Brechites vaginiferus(Dreyer et al. 2003). It is thus argued that the Cla-vagelloidea comprises two families, both evolved atdifferent times from a lyonsiid ancestor, and thattheir various representatives constitute an extraordi-nary example of parallel evolution. Bryopa is an,albeit highly aberrant, endolithic member of theClavagellidae.

Acknowledgments. Dr Hiroshi Saito, National ScienceMuseum, Tokyo, kindly allowed me to examine thespecimens of Bryopa aligamenta herein reported upon.I am also grateful to Dr. E. Harper, Department of EarthSciences, University of Cambridge, and Ms. Kathie Wayand Dr J. Todd, both of the Natural History Museum,London, for allowing me to examine material in the col-lections of these institutions. Dr. J. D. Taylor and Dr.A. Ball, also of the Natural History Museum, London,kindly took the SEM photographs herein reported upon.

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218 Morton


Appendix

Figure abbreviations

AA Anterior adductor muscle or scar

AGI Anterior growth increment

C Crypt

CM(I) Inner layer of circular muscles

CM(O) Outer layer of circular muscles

CPS Coral polyp skeletons

DD Digestive diverticula

D-V Dorso-ventral growth axis of the shell

ES Exhalant siphon

ET Etched area of shell

EU Dorsal projection: possibly the remnant of a heavily eroded umbo

F Foot

H Haemocoel

HE Heart

HP Hinge plate of right valve

HP? Hinge plate of left valve?

HT? Hinge tooth?

ID Inner demibranch

IE Inner epithelium

IGI Internal growth increment

ILP Inner labial palp

IMF Inner mantle fold

IS Inhalant siphon

K Kidneys

LM Longitudinal muscles

MG Mucous gland

MM Mantle margin

NL Nacreous layer

OD Outer demibranch

OE Outer epithelium

OLP Outer labial palp

P Pericardium

PA Posterior adductor muscle or scar

PC Pallial crest

PE Periostracum

PE (IL) Inner layer of periostracum

PE (OL) Outer layer of periostracum

PEL Periostracal layers

PG Pedal gape

PL Pallial line

PN Pallial nerve

PR Prodissoconch

PRL Primary ligament

PRM Pallial retractor muscle

PS Pallial sinus

R Rectum

SC Siphonal canal

SG Siphonal gland

SM Suspensory muscles

SN Siphonal nerve

T Testes

TM Transverse muscle fibres

U Umbo



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