PROC. R. SOC. VICT. vol. 96, no. 3, 113-125, Septem ber 1984

SYSTEMATICS, ANATOMY AND BORING MECHANISMS OF THE ROCK-BORING MYTILID BIVALVE BOTULA

By B. R. W ilson and R ichard T a it

M useum of Victoria, 285-321 Russell Streel, M elbour ne, Victoria, Australia 3000

A bstract : The mytilid Botu/a is shown to contain a single species, B. fusca Gmelin, which is widespread in tropical and sub-tropical waters of t he Indian, Pacific and western Atlantic O ceans. She ll m orphology and anatom y of this species are describe d. It is siphonate and bores in calcareous rocks an d dead corals by m eans of non-acid secretions from la rge boring glands in the m antle folds anteriorly an d posterodorsally. Its nearest living relatives are t he species of Lilhophaga s.s. and the genus is placed in the Lithophaginae along with Adula, Lilhophaga, Leiosolenus and Fungiacava.

Recent classifications place the mytilid Botula M orch Natural History, Paris. NMV —Museum of Victoria, 1853 in the Modiolinae (e.g. Soot-Ryen 1969, Keen Melbourne. SAM —South Australian Museum, 1971). Other genera placed in that group are non- Adelaide. SDNHM —San Diego Natural History siphonate byssally attached ‘nestlers’ while Botula is a Museum, San Diego. WAM —Western Australian siphonate, rock-borer. Lamy (1937) and other author s M useum, Perth. place Botula in the Lithophaginae. This paper reports results of an anatomical study of Botula fusca, under­ taken to determ ine the affinity of the genus, to re view its SYSTEMATICS species taxonomy, and to determine the nature of th e Class B ivalvia boring mechanism. Family M ytilidae Genus Botula M orch 1853

METHODS 1853 Botula M orch, p. 55. 1939 Iredale, p. 414. (Type species: Living specimens of Botula fusca were collected and Botulopa Botulopa studied at the Heron Island M arine Research Station , in silicula infra Iredale, 1939 (= M. fusca herein))

the Great Barrier Reef Marine Park, Capricorn Zone. T ype species : Mytilus fuscus Gmelin 1791 by subse­ Supplementary preserved specimens were examined quent designation of Dali 1898. from several other Queensland and W estern Australia n D ia gnosis : Shell cylindrical, inflated, arcuate, sm ooth localities. For com parative purposes sections were made or finely concentrically striate, rather thin, white with a of the pallial boring glands of Leiosolenus lessepsianus, uniform thin, smooth, glistening brown periostracum . also collected at H eron Island. Umbos terminal, prosogyrate conspicuously incurved; Isotonic M gCh was used as an anaesthetic prior to hinge-line and ligament short, ligament opisthodeti c, dissection. Anatomical drawings were done from the parivincular; margins smooth except for fine vertic al anaesthetised specimens, free-hand or using a camer a- striae beneath and immediately posterior to the lucida. Specimens for histological work were fixed in ligament. Bouin’s solution, stored in 70% ethanol, routinely pro­ Incurrent and excurrent siphons long but usually cessed into paraffin blocks and sectioned at 5 /x. Sections divided; with a muscular septum within the tubular ex­ were taken in a plane perpendicular to the mantle e dge current siphon and a prom inent digitate ventral sip honal (transversely across the boring gland) and stained with branchial membrane. Ctenidia filibranchiate and M ayer’s haemotoxylin and eosin, M allory’s triple stain heterorhabdic, eleutherorhabdic. Boring glands pres ent or W iegert’s iron haemotoxylin. The periodic in the inner mantle folds anteriorly and postero­ acid —Schiff reaction (P.A .S.) in conjunction with Al- dorsally. Posterior siphonal retractor muscles and scars cian Blue (pH 2.35) was used as a test for acid or neutral present; anterior pedal retractors attach close to the mucopolysaccharides (M owry 1956). margin of the hinge just below the umbos; posterior Shells of the specimens on which the anatomical pedal-byssal retractors small. study is based are deposited in the M useum of Victo ria Mussels which bore in dead corals, coral-rock or Melbourne, the Australian Museum Sydney, and the other calcareous rocks. Western Australian Museum Perth. Abbreviations for respository institutions are as follows: AM —A ustra lian R emarks : M orch assigned to Botula only the species Museum, Sydney. ANSP—Academy of Natural arenaria M eusch. (with vagina Lamarck, and castaneus Sciences of Philadelphia, Philadelphia. BM(NH) — ‘Rum phius’ Gray (non Say) listed as synonyms) and British Museum (Natural History), London. fusca Gmelin (with M ytilus brunneus Solander, Modiola CAS —California Academy of Sciences, San Francisco. cinnamomea Lamarck and M. favanii Potiez and LACM —Los Angeles County Museum, Los Angeles. M ichaud listed as synonyms). Subsequently Dali (189 8) MCZ —Museum of Comparative Zoology, Harvard selected fusca Gmelin as type. In these authors’ opinion University, Boston. MNHN —National Museum of arenaria, a large, thin-shelled, siphonate mytilid which

113 114 B. R. WILSON AND RICHARD TAIT burrows in soft substrates of the central Indo-Pacific See Table 1 for details of type specimens. region, is not congeneric with fusca, although its correct D istr ibution : W idespread in the tropical and sub­ generic affinity is yet to be determ ined. tropical seas of the Indian, Pacific and western Atlantic Botula most resembles Lithophaga s.s. in that the Oceans. Apparently absent from the tropical eastern shell has a strong periostracum but no secondary A tlantic. Figure 7 is based on verified m useum spec imen calcareous accretions, there are prom inent plicate mem­ records and selected literature records. branes in the roof of the mantle cavity, and boring is aided by chemical secretions from anterior and dors al H abitat : Botula fusca is a boring mytilid inhabiting boring glands. It is easily distinguished from that genus dead corals, coral rocks and other calcareous rocks . It is by the short, arcuate shell form, the large, strong ly common in the intertidal zone and has been collecte d incurved umbos, and the divided posterior siphons. from suitable substrates to depths as great as 291-190 fathom s (off Hawaii, see Dali, Bartsch & Rehder 193 8). Botula fusca (Gmelin 1791) It is often extraordinarily abundant in coral rocks and Figs 1 A -P, 2 B-F, 3-7 the coral-rock platform of the reef-crest zone, sometimes most commonly with the burrows opening on 1785 Mytilus cinnamominus Chem nitz, pi. 82, fig. 731. the underside of the rocks. The species may also be (Refers to Lister, 1687, fig. 197.) (Type locality: abundant burrowing in sloping beach-rock relatively Jam aica.) (Non-binomial publication.) high in the intertidal zone, e.g. along the souther n shore 1791 M ytilus fuscus Gmelin, p. 3359. (Refers to Lister, of Heron Island (Queensland) below the research sta ­ 1687, fig. 197.) (Type locality: Jam aica.) tion. It is also known to burrow in the shells of o ther 1793 Mytilus cinnamomeus Schreibers, p. 293. (Refers molluscs such as Strombus gigas (Chemnitz 1785) and to Chem nitz, 1785, pi. 82, fig. 731.) oysters (Berry 1959). In northern A ustralia it is c ommon 1807 Modiolus cinnamomeus Link, p. 147. (Refers to boring in massed shells of rock-oysters (Saccostrea) high Chem nitz, 1785, pi. 82, fig. 731.) in the intertidal zone. 1819 Modiola cinnamomea Lamarck, p. 114. (Type Gohar and Soliman (1963) have described and locality: l’lsle de France (Mauritius, Indian figured burrows of this species (identified as Modiolus Ocean), leg. M . Desetangs.) cinnamomeus Bruguiere) from the Red Sea. The burrow 1819 M odiola silicula Lam arck, p. 114. (Type locality: lacks a calcareous lining and is differentiated into two ‘Nouvelle Hollande’ probably collected by Peron parts. The outer or siphonal part is roughly dumb-b ell during the Baudin Expedition at Shark Bay, shaped in cross-section and it widens distally. The inner W estern Australia.) part, which is occupied by the shell, is kidney-sha ped 1844 Modiole favanni Potiez & M ichaud, p. 130, pi. 54, like the shell. fig. 9. (Type locality: ‘Exotique’.)

1892 Lithodomus projectans Tate, p. 130, pi. 1, fig. 1. D escr iption : Shell. W hite to pale brown, covered by a (Type locality: ‘Port Darwin’.) uniform tan to dark-brown or almost black glossy 1938 Botula hawaiensis Dali, Bartsch & Rehder, 1938, sm ooth periostracum . Cylindrical-arcuate, anterior and p. 59, pi. 12, figs. 1-4. (Type locality: ‘dredged by posterior ends broadly rounded; prosogyrate umbos the U.S. Bureau of Fisheries Steamer “A lbatross” large and term inal, sometimes conspicuously projecting at Station 3845 off the south coast of M olokai and incurved. Ligament opisthodetic, parivincular, (Hawaii) in 60-64-0 fathom s on sand, pebble and short and thick, resilium entire, sub-ligamental ridge shell bottom ; bottom tem perature 71 °F.’) lacking; hinge edentulous, margins smooth except fo r 1938 Botula laysana Dali, Bartsch & Rehder, 1938, p. very fine, oblique striae on the dorsal margin bene ath 60, pi. 12, fig. 5. (Type locality: ‘dredged by the and immediately behind the ligament. Exterior smoot h U.S. Bureau of Fisheries Steamer “Albatross” at except for weak concentric growth striae and, in so me Station 3936, near Laysan Island (Hawaiian cases, series of concentric ridges presumably repre ­ Islands) in 79-130-0 fathom s on small broken shell senting successive growth phases (Fig. ID , G; cf. and coralline bottom ; bottom tem perature 68°F.’) Lithophaga teres and L. antillarum, W ilson 1979, p. 1939 Botulopa silicula infra Iredale, p. 415, pi. 6, fig. 440, 448). Scars of anterior and posterior retracto rs 26. (Type locality: Low Isles, Queensland.) weak but usually discernible, scar of siphonal retr actor 1959 Botula cylista Berry, p. 108. (Type locality: Punta very weak but discernible. Cameron, M azatlan, Sinaloa, Mexico.) A natom y (see also Pelseneer 1911, Soot-Ryen 1955,

Fig. 1 — A , B M odiola cinnamomea Lam arck; syntype (left valve of the whole specim en ), M NH N (Paris); from TIsle de France’, leg. M. Desetangs. C, M odiola silicula Lamarck; type M NHN (Paris); from ‘Nouvelle H ollande’. D, E, Botula hawaiensis Dali, Bartsch & Rehder; holotype, USNM 484180; off M olokai, Hawaii. F, Botula laysana Dali, Bartsch & Rehder; holotype, USNM 335614. G, H , Botula fusca USNM 257854; (34°05'N, 77°18'W ). I, J, Botula fusca NM VF51471; Heron I., Queensland. K, Botula fusca USNM150313; St. George Cay, Belize. L, M, Botula cylista Berry; paratype; SDNHM 428303; Punta Cameron, M azatlan, M exico. N, Botula fusca USNM 173161; off Green Cay, Baham as. O, P, B otula silicula infra Iredale; holotype, AM C60400; Low Isles, Queensland . MYTILID BIVALVE BOTULA

inc^»oC\>- $ * Ci. cc*. .•£

jl L^ i UoCCtXufrt- - ( typ e. Ol ■ Lcs.wt.o^-ri'^

1 cm 116 B. R. WILSON AND RICHARD TAIT

T able 1

L ocation and D imensions of T ypes

Length H eight W idth Lig. Length cm cm cm cm

M odiolus cinnamomea Lamarck 2 syntypes: 1 whole shell 2.69 1.48 1.23 1.26 and 1 left valve, Lamarck 2.94 1.60 0.63(!/2) 1.54 Collection, M NH N (Paris)

M odiolus silicula Lamarck Whole specimen, Lamarck 2.47 1.12 1.06 1.37 Collection, M NH N (Paris)

M odiole Favanni Potiez & Type not located — — _ _ M ichaud

Lithodom us projectans Tate Whole specimen, SAMD14615 — — — _ Botula hawaiensis Dali, Bartsch Whole specimen, USNM484180 1.50 0.99 0.93 0.78 & Rehder

Botula laysana Dali, Bartsch Whole specimen, USNM335614 0.94 0.62 0.7 1 _ & Rehder

B otulopa silicula infra Iredale W hole specimen, AM C60400 2.73 • 1.71 1.17 1.08

B otula cylista Berry H olotype not located Paratype, whole specim en 1.93 1.21 1.07 — SDNHM 42803

G ohar & Soliman 1963). Anterior adductor elongate- horizontal aperture and backward folded rim (Fig. 3 ). It ovate and lies close to the antero-ventral margin. forms a ‘tube within a tube’, presum ably functionin g as Posterior adductor ovate, rather small, conspicuous ly a velocity control device for the excurrent water flow. A divided into ‘quick’ and ‘catch’ parts, and located quite similar structure occurs in Lithophaga and Leiosolenus far posteriorly. Anterior retractors moderately str ong (W ilson 1979). and insert close to the hinge margins below the um- The ventral incurrent siphon is flanked by muscular bones. Posterior retractors small (compared with by ssal- flaps which form a functional siphonal tube by appo si­ attached mytilids such as M odiolus) insert above the tion of the ventral edges. The branchial septum bea rs a antero-dorsal side of the posterior adductor; altho ugh ventral digitated ‘valvular siphonal m em brane’ (Yon ge separate pedal (anterior) and byssal (posterior) re tractor 1955) like that of M ytilus (Kellogg 1915), Lithophaga strands arise contiguously (but distinguishable at the (Yonge 1955, W ilson 1979), Adula (Fankboner 1971) place of origin in the foot-byssus complex) they me rge and Xenostrobus (W ilson 1967). Soot-Ryen (1955, fig. dorsally and insert as a single muscle block. A wid e band 72) illustrates this structure. The membrane is usu ally of scattered siphonal retractor strands, originatin g from asymmetrically digitated, with 10 or more digits on the the m antle in the region of the siphon, inserts on the side large central flap, a smaller flap with 2 or more d igits on of each valve antero-ventral to the posterior adduc tor. each side, and a single digit in each lateral corne r. Yonge The edges of the mantle from the umbo ventrally (1955) suggested that this organ ‘serves to shield the around to the postero-dorsal corner possess inner, (outgoing) waste materials from the broad incoming middle and outer folds, as in other mytilids, the o uter stream of water’. and middle folds adhering closely to the shell marg ins. The ctenidia are filibranchiate, eleutherorhabdic a nd The inner folds meet and fuse antero-ventrally from the heterorhabdic. There are no inter-lamellar junction s as um bo to a point a short distance behind the anterio r ad­ in M ytilus, but every 5th or 6th filament is a ‘principal ductor, and also along the postero-dorsal side; ven trally filam ent’ (see Type B (lb) of A tkins 1937, text-fig. 4) with they are separate but appositioned in life to enclo se the a connecting septum rising to about half way up the gill. m antle cavity; posteriorly they are thickened, musc ular The inner and outer demibranchs are about equal in and form extensible muscular siphons as in Lilhophaga, height; ascending lamellae are a little shorter tha n the Leiosolenus and Adula (see Pelseneer 1911, Yonge 1955, descending ones. The free edges of the ascending Soot-Ryen 1955, Fankboner 1971, W ilson 1979). lamellae meet (but do not fuse with) the mantle or In most specimens the siphons are separate for most visceral mass. Conspicuous food grooves run along the of their length (Figs 3, 6) but in odd individuals they are bottom edge of each demibranch. The labial palps ar e joined as in Lithophaga and Leiosolenus. They are fused broad and strongly plicate on their inner surfaces. The by a horizontal branchial septum anteriorly, beneat h hind-gut is normally looped, has no special style-s ac, which the gill axes attach. and the rectum passes through the ventricle. The au ricles The dorsal excurrent siphon is com plete and tubular . are heavily pigmented reddish-brown. Pericardial glands Internally across its inner (anterior) end there is a thin are not evident on the walls of the pericardium . Th ere is but muscular suprabranchial valve or diaphragm with a a dorsal cul-de-sac of the m antle cavity running fo rward MYTILID BIVALVE BOTULA 117

Fig. 2 —H istology of the pallial boring glands in Botula fusca and Leiosolenus lessepsianus (the latter from a living Acropora colony) from Heron Reef, Queensland. A, Leiosolenus lessepsianus NM VF31815; horizontal section through the anterior gland show ing a diverticulate lum en. Stained with H & E. x 160. B, Botula fusca (NM VF31814); horizontal section through the anteri or gland showing glandular m iddle and inner folds. Stained with H & E. x 87. C, Botula fusca (NM VF31817); transverse section through the dorsal gland in an anterior pos ition over the pericardium show ing fusion of the in ner folds down a m id-line ridge with sm all secondary la teral flaps, thick and glandular m iddle folds, and thin outer folds (visible on the right side only). Stain ed with H & E. x 260. D, Botula fusca (NM V F31817); as for Figure C but sectioned further posteriorly, beh ind the pericardium and over the dorsal cul de sac of the m antle cavity; note the enlarged secondary flap s of the fused inner folds. Stained with H & E. x22 0. E , Botula fusca (NM VF31817); enlargem ent of the dorsal gland m iddl e fold. Stained with H & E. x 530. F, Botula fusca (NM VF31817); as for figure E, but stained with M al lory’s Triple Stain. N ote dark bodies stained red with Acid Fuchsin. x530. 118 B. R. WILSON AND RICHARD TA1T

aur

Fig. 3 —Generalized diagram of the anatomy of Botula fusca from Heron Island, Queensland (NM VF51471). Left valve, m antle lobe and ctenidium rem oved; posterior siphons shown in saggital sec­ tion. M id and fore-gut not shown. Abbreviations: a b gl— anterior boring gland, a a k — anterior arm of kidney, a add— anterior adductor m uscle, an — anus, a ret — anterior retractor m uscle, aur— auricle. bs — branchial septum , by— byssus. ct — ctenidium . d—diaphragm within excurrent siphon, dg — digestive gland, d m c—dorsal m antle cavity cul de sac. exs — excurrent sip h on .// — fool, g ax—gill axis (left side, gill detached), gen ap — genital aperture. /V?/ — intestine, inc s—incurrent siphon. Ip— labial palps (left). m — m esosom a m & o m / —middle and outer mantle folds, p a —posterior adductor m uscle, p a k — posterior arm (dorsal and ventral loops) of kidney , pd b gl— postero-dorsal boring gland, p b r—posterior byssal retractor m uscle, pi m — plicate m em branes, p /■ —posterior pedal retractor m uscle. rec— rectum , ren ap — renal aperture. 5 r m — siphonal retractor m uscles, v — ventricle, v s m — valvular siphonal membrane.

above the posterior adductor and rectum to the Boring glands are located in the middle and inner posterior wall of the pericardium as in Mytilus, folds of the mantle lobes anteriorly and in the mid dle Lithophaga and Modiolus. Left and right kidneys com­ folds posterodorsally. The anterior boring gland is a prise a relatively thick-walled tubular organ, line d with conspicuous, convoluted organ located between the heavily pigmented (reddish-brown) tissue, with reno - anterior adductor and the umbos, just below the jun c­ pericardial openings in the anterolateral corners o f the tion of the outer m antle folds (Fig. 3). M iddle and inner pericardium. An arm of the kidney tube runs forward mantle folds (Fig. 2B) are covered with ciliated co lum­ for a short distance above the ctenidial axis; the broader nar epithelium composed of cells 9-24 n in height. The part of the kidney runs backwards to the anterior a nd middle fold has a longitudinal furrow on its median sur­ ventral edges of the posterior adductor and then face, also lined with ciliated cells. A shallow lay er of recurves ventrally, lying above the gill axis, term inating heavily vacuolated subepithelial cells overlies a d ense at the renal aperture in the roof of the m antle cav ity in a bundle of collagen fibres which runs longitudinally position approximately below the centre of the pericar­ along the edge of the fold. This bundle occupies th e bulk dium. There are large, conspicuous plicate membrane s of the middle mantle fold so that secretory activity is on both sides and the full length of the gill axes (Fig. 4). restricted to the peripheral area. The inner m antle folds Gonad tubules lie superficially over the digestive are convoluted and covered with a minutely folded gland dorsally, fill m uch of the space between the diverg­ epithelium of secretory and ciliated cells 16-22 /+ in ing posterior retractors, invest the m antle lobes, and fill height. The subepithelial region is a loose m atrix of col­ a large mesosoma. The genital aperture is located o n a lagenous fibres with a large number of spaces. The papillum adjacent to but not contiguous with the re nal glands are drained by a large num ber of short, bran ched aperture (Fig. 4). ducts, all lined with ciliated colum nar epithelium . In the MYTILID BIVALVE BOTULA 119

epithelium, and some vacuoles in the subepithelium, bodies 7-15 n in diam eter can be seen. Presum ably, these are secretory droplets; they show a positive P.A .S. re­ action, but do not stain with Alcian Blue. In the posterodorsal region behind the ligament the inner mantle lobes appear to have little secretory ac­ tivity. The epithelial cells are cuboidal with roun d nuclei and have no visible inclusions. However, the middle mantle folds in this region are glandular (Fig. 2 C -F) with m any eosinophilic inclusions staining red with Acid Fuchsin (Fig. 2F), and a secretory, ciliated epithe lium of colum nar cells 10-12 /t in height. The subepitheliu m is a loose matrix with a large number of intra and extra ­ cellular droplets which can be seen to pass to the exterior through minute and otherwise invisible ducts. These secretory droplets stain strongly P.A .S. positive u sing an Alcian Blue, P.A .S. technique. Ventrally, the middle folds of the mantle lobes do Fig. 4 —Diagram of posteroventral area; m esosom a di splaced contain secretory cells, but there is no enlarged g land. to the right exposing the plicate organs, genital a perture and Nor was any glandular structure observed in the renal aperture of the left side betw een the viscera l m ass and the posterior siphons. gill axis. (Specim en from H eron I., Queensland; NM V F51471).

DISCUSSION

M orphological V ariation and T axonomy of the

S pecies F ossil R ecord Intra-population variation in shell morphology of Botula fusca appears to have a long fossil history as these mussels is extreme, apparently relating to th e well as a wide distribution. Dali (1898) reported a fossil nature of substrates in which they bore. No geograp hic under this name from the Oligocene of Florida. Botula patterns of variation could be discerned, even betw een cordata (Lamarck 1807) from the Eocene of France, the W estern Atlantic and Indo-W est Pacific popula­ Senegal, Libya and Egypt (see Freneix & Gorodiski tions. The few specimens we have seen from the eastern 1963) and Lithophaga mcknighti H anna 1927 from the Pacific fall well within the range of variation of the en­ Eocene of California (see M oore 1983, pi. 19, figs 9, 10) tire series. We can find no morphological grounds f or may also be this species. A plastotype of the latte r fossil giving that population separate taxonom ic status an d we in the collections of the CAS is indistinguishable from confidently place Botula cylista Berry in the synonymy living B. fusca shells. of B. fusca. One feature of interest is the colour of the S pecies N omenclature periostracum. In some specimens it is light chestnu t The first published reference to this species is a poor brown; in others, it is dark brown or black. Both c olour but recognizable illustration by Lister (1687). No forms are found throughout the species’ range, and in locality is given specifically for this figure but it is fram ed some places (e.g. Heron Island) they may be found b ur­ with a figure of a Modiolus which bears the word rowing in the same rocks. The significance of this ‘Jam aic’. dimorphism is unknown to us. Chem nitz (1785) published a reasonably good figure, Anatom ically, this mussel is quite uniform . The only referred to duplicate m aterial in the Spengler collection character showing variation is the digitation on th e from the Nicobar Islands, and stated that the species valvular siphonal membrane on the ventral side of the bores in the shells of other molluscs and corals an d that branchial septum (see anatomical description and Fig. his own material was found in a W est Indian specime n 5A, B). However, there is no evidence of geographic of Strombus gigas. W ith this illustration, Chemnitz in­ pattern in this variation. troduced the name 'Mytilus cinnamominus’. It is clear We have pondered at length the widespread nature that the Lister and Chemnitz figures illustrate the same of this mussel and whether m ore than one species might species. be involved. The logical modus operandi must be to In the Portland Catalogue, Lightfoot (1786, p. 104, assum e a single species unless, or until, there is evidence number 2275) listed Mytilus Brunneus but gave no of reproductive isolation or morphological or other reference or description. Although some authors (e.g. evidence which implies genetic divergence. In this case Lam y, 1937, p. 179) place this nam e in the synonymy of (with the worrying exception of periostracum colour ) cinnamomea (= fusca) it should be regarded as a nomen evidence of discrete morphs is lacking. Therefore w e nudem. conclude that there is but a single living species of In 1791 Gmelin referred to the figure by Lister and Botula, widely distributed in coastal tropical waters with provided for it the name ‘Mytilus fusca’ but gave no the apparent exception of the eastern Atlantic. locality data. Subsequently, Schreibers (1793) and Link 120 B. R. WILSON AND RICHARD TAIT

becomes unimportant once it is accepted that there is but a single species widely distributed in the Indian, Pacific and A tlantic Oceans. The oldest available n am e, M. fusca Gmelin, must be used for all. It is unfortunate that this name is based on a poor illustration, with dubious provenance, in a rare publication, and that there is no type.

B oring M echanism Boring in calcareous substrates is achieved by certain mytilids by mechanical abrasion (rubbing of the she ll valves against the burrow wall), by chemical means, or by a com bination of the two. Boring glands in the m an­ Fig. 5 — Valvular siphonal m em brane of Botula fusca (com pare tle folds have been described in species of Lithophaga also with Fig. 2): A, ex Brittomart Reef, Queenslan d (Pelseneer 1911, Turner & Boss 1962, W ilson 1979, (NM VF51472). B, ex Isla Tortuga, Venezuela (redrawn from M orton & Scott 1980) Leiosolenus (Yonge 1955, W ilson Soot-R yen 1955, text-fig. 72). 1979, Kleeman 1980, Morton & Scott 1980) and Fungiacava (Goreau, G oreau, Soot-Ryen & Yonge 1969, (1807) used the nam e ‘cinnamomeus’ citing the Chem nitz Goreau, Goreau & Yonge 1972). illustration. Morton and Scott (1980) have described the In 1819 Lam arck used ‘Modiola cinnamomea’ citing histology and morphology of anterior and postero- both the Chemnitz and the Lister figures (referring to dorsal boring glands in the middle mantle folds of a the latter as ‘var. (b)’) but also referring to spe cimens in number of Lithophaga and Leiosolenus species. They his own collection from TIsle de France’. Types exist in established that there is a ‘progressive degree of com­ the M NHN (Paris) Lamarck Collection (Fig. 1A, B). plexity from simple epithelial to ducted sub-epithe lial There are two samples. One sample consists of a who le structures coinciding with increasing specializatio n of specimen and a single left valve, labelled as the l’lsle de habitat from natural limestone to species specific live France material collected by M. Desetangs; the coral dwellers.’ They also described a siphonal gla nd in specimens have a chestnut brown periostracum. The the m ore specialized species (of Leiosolenus). other sample consists of four whole specimens and two Lithophaga lithophaga (Linnaeus) and L. teres valves without locality and the type status of this (Philippi) which bore in limestones and dead corals , are m aterial is uncertain. examples of species with large but histologically s imple In the same publication Lamarck described another anterior and posterodorsal boring glands and no mussel, under the name Modiola silicula, from New siphonal glands. Leiosolenus simplex (Iredale) (= lessep- Holland (W estern Australia). The type (Fig. 1C) is a siana, see Wilson 1979) and Leiosolenus mucronata whole specimen in the M NHN (Paris) Lamarck Collec­ (Philippi) are the extreme examples of the specialized tion. It is clearly conspecific with the types of M. cin­ live-coral dwellers. namomea Lam arck, although it possesses a dark brown In Fungiacava eilatensis, which bores in living periostracum . Fungia, boring is exclusively chemical. The shell never The publication of Chemnitz is not an accepted comes in contact with the walls of the burrow and there source of available names and so M. fusca Gm elin 1791 are large boring glands in the middle mantle folds, in­ becomes the first available name which is based on the cluding in the siphonal regions (Goreau et al. 1972). Lister figure and we may assume that the type locality is Yonge (1955) compared the boring mechanisms of Jam aica in the Atlantic. ‘Botula’ and ‘Lithophaga’, concluding that they are The names M. cinnamomea Lamarck and M . silicula essentially mechanical in the form er and chemical in the must be associated with the Indo-W est Pacific popul a­ latter. Although the results of that study are not tion because of the clearly designated Indian Ocean disputed here, they apply not to Botula and Lithophaga localities with the type material. Some authors (e.g. but to Adula and Leiosolenus. The species studied were Iredale 1939) have assumed that the Atlantic and In do- Adula falcata (identified as Botula {Adula) falcata) and W est Pacific populations are different species. In that Leiosolenus plumula (identified as Lithophaga case M. fusca Gmelin would be the available name for plumula). the Atlantic form, but M. cinnamomea Lamarck could Gohar & Soliman (1963) discussed the boring not be used for the Indo-W est Pacific form because the mechanism of Botula fusca (misidentified as Modiolus name was already validly used by Schreibers and Lin k cinnamomeus) from the Red Sea, but failed to observe for the Chem nitz figure (i.e. it is a subjective sy nonym of boring glands. They described the boring mechanism in M. fusca Gmelin). It was for this reason that Iredale this species as ‘by mechanical abrasion, in a rocking used the second available nam e of Lam arck, i.e. silicula, movement’. for the Indo-West Pacific population when he un­ In this study it is shown that Botula fusca has large necessarily provided the subspecific name infra for the but histologically simple anterior and posterodorsa l bor­ Queensland form (Fig. lO , P). However, this problem ing glands and lacks siphonal glands, thus m atching the MYTILID BIVALVE BOTULA 121

a ret p f, r Fam ily Placem ent of B otula Although Lamy (1937) placed Botula with Lithophaga, Dali (1898) Iredale (1939) Keen (1937, 1971) Soot-Ryen (1955, 1969) and others have con­ sidered that Botula is a relative of Modiolus in view of similarity of shell form though noting the peculiar musculature of Botula. In fact, the cylindrical, slightly arcuate shell of Botula with its large, terminal and in­ curved umbos and wide, blunt anterior end, is quite atypical of Modiolus. Nor does Botula possess a hirsute periostracum which is an important feature of Modiolus', the periostracum is thin and glossy smooLh. Anatomically there are many differences besides m usculature. M ost significantly, Botula fusca has large Fig. 6 —M usculature of Botula fusca. (Specimen ex Heron I., extensible siphons with an internal diaphragm within the Queensland; NM VF51471). excurrent siphon, boring glands in the mantle folds and condition of Lithophaga s.s. and the least specialized a large, digitate valvular siphonal m em brane on the ven­ Leiosolenus species which bore in calcareous rocks and tral side of the branchial septum and the posterior dead corals. retractor muscles are small. These major anatomical M orton & Scott (1980) postulate a ‘progressive characters exclude any possibility of a close affin ity with reduction in shell length relative to width and hei ght’ Modiolus. On the contrary, these features and the and ‘a progressive reduction in size of the adducto r and burrowing lifestyle are consistent with a lithophag ine byssal retractor muscles’ in the Lithophaga-Leiosolenus affinity. series correlating with habitat specialization. Botula W ilson (1979) commented on significant anatom ical fusca is short, cylindrical, blunt ended and has very differences between Lithophaga s.s. (as represented by small posterior byssal retractor muscles, and it do es not L. lithophaga Linnaeus, L. niger d’Orbigny, L. teres fit this postulated morphological trend. Philippi, and L. antillarum d’Orbigny) and the series of M any authors (Carazzi 1903, Pelseneer 1911, Yonge species which possess secondary calcareous accretio ns 1955, Franc 1960, Turner & Boss 1962) have supposed on the posterodorsal parts of the valves. Further that the chemical agent secreted by the boring glan ds of evidence for generic separation of these two groups of lithophagines is a free acid and the organs are ref erred to boring mussels has been provided by M orton and Scott in the older literature as the ‘acid glands’. M ore recent (1980) who showed differences in the structure and loca­ authors accept a contrary view that the boring agen t is a tion of the boring glands. calcium-binding neutral mucoprotein, following the W aller (1983) has shown that the periostracum of th e results of histo-chemical studies on L. lithophaga by Lithophaga s.s. series has a mineralized outer layer con­ Jaccarini et al. (1968). In that species secretory cells taining calcium hydroxyl-apatite, with an X-ray dif frac­ from the boring glands are strongly P.A .S. positive and tion pattern like that of dahllite, apparently a de vice for do not stain with Alcian Blue, thereby excluding th e hardening the periostracum helping to protect the shell possibility of an acid m ucopolysaccharide secretion . The from abrasion during burrowing. This substance is lack­ results of our histo-chem ical tests confirm that th is is the ing in the periostracum of the species with seconda ry case in Botula fusca also. calcareous accretions which appear to be an alterna tive

T able 2

D iagnostic C haracters of the G enera of L ithophaginae

ADULA LITHOPHAGA BOTULA LEIOSOLENUS FUNGIACAVA

Shell elongate — Shell elongate — Shell short — Shell elongate — Shell high, ovate cylindrical cylindrical cylindrical cylindrical

Umbones subterminal Umbones subterminal Umbones termi nal, Um bones subterminal Um bones subterm inal, strongly incurved strongly incurved

Boring glands lacking Anterior and postero- Anterior and postero- Anterior and postero- Boring glands present. dorsal boring glands dorsal boring glands dorsal glands pre­ present, sim ple; present, sim ple; sent, sim ple or siphonal boring siphonal boring com plex; siphonal glands lacking. glands lacking. boring glands present.

7 Plicate m embranes Plicate m embranes Plicate m em branes ? present. present. lacking.

Siphons undivided Siphons undivided Siphons divided Siphons undivided Siphons undivided 122 B. R. WILSON AND RICHARD TAIT

i i i______i______i______i______i______I______i______i------1 i — 0° 30° SO0 90° 120° I SO0 I SO0 150° 130° 900 SO030°

Fig. 7 — Distribution of Botula fusca based on specim ens in m useum collections exam ined by the authors (♦ ), and selected literature records (■ ).

device serving, in part, the same function. For these Florida: Miami (ANSP, MCZ, USNM, BMNH); reasons Leiosolenus is here restored to generic rank to 3-30 fms off Miami (USNM); 25-60 fms, off Fowey include the species which possess secondary calcare ous Light (USNM); 30 ft,m 8-10 m. W of Mullet Key, Fort accretions on the shell valves but lack a mineraliz ed Dade (ANSP); 10-14 fms, off Palm Beach (ANSP); outer layer in the periostracum , and possess pocket-like M iddle Grounds, NW of Johns Pass, off St. Petersbur g supra-branchial chambers between the gill axes and the (MCZ); Tampa Bay (MCZ); 65 fms off W estern Dry visceral mass but lack plicate membranes. Docks (USNM); Key West (MCZ, ANSP, USNM); Goreau et at. (1970) argued that Fungiacava is m ost 65 fms off Ragged Key (USNM); 1 m off Soldier Key closely related to Solamen and Crenella (subfamily (MCZ); Bonefish Key (ANSP); in soft rock, No Name Crenellinae) but Morton & Scott (1980) favour a Key, near Big Pine Key (USNM); 15-16 fms, Tortugas lithophagine affinity for this unusual genus. The latter (USNM); Garden Key (CAS). view is accepted here. Texas: 103 and 107 mi. SE of Galveston (MCZ). It is proposed here that the subfamily Lithophagina e Bahamas'. Off Green Cay (USNM); Grand Bahamas be redefined to include five genera of siphonate, r ock- (USNM); N end Elbow (Little Guana) Cay, Great boring mytilids (Table 2): Adula which bores by Abaco (ANSP); Bimini Lagoon (ANSP); 3 fms, Caicos mechanical means and Lithophaga, Leiosolenus, Bank off Ambergris Cay (M CZ); Andros (MCZ). Fungiacava and Botula which bore by means of chemical secretions from boring glands located in the Bermuda: (BMNH); 80-100 fms, 3A mi. S of Castle m antle folds. Botula appears to be most closely related Road (MCZ); 4-5 fms, Castle Roads, Castle Harbour to Lithophaga. (MCZ). Cuba: 25 fms Cabanas Harbour (USNM); Cape Cajon (USNM ); 1-12 fms Bahia H onda (USNM ); Cao Cruz del Padre, Santa Clara (USNM). LOCALITY RECORDS Dominican Republic: Santa Barbara da Samang, Santo The following list is based on verified museum Domingo (MCZ). specimen records and selected literature records wh ere Haiti: (BMNH). these add significant information. Abbreviations an d spelling are as given on the original record. Puerto Rica: Punta Arenas, Vieques (USNM); Mayaguez Harbour (USNM).

A tlantic Virgin Islands: St. Thomas (ANSP, MCZ, USNM). North Carolina: In coral rock, 14 fms, 34°05'N, Barbados: 10-20 ft, off Pelican I. (USNM ). 77°18'W (USNM); 14 fms, 25 miles SE of Cape Fear Belize: Coral reef near St. George Cay (USNM). (USNM); 18 fms, 27 miles SE of Cape Fear (USNM). Trinidad: Chaguaramas Bay (USNM).

South Carolina: Sullivan I. (M CZ). Tobago: E of Pigeon Point (USNM). MYTILID BIVALVE BOTULA 123

West Grenada: 6 ft, M orne Rouge Bay (ANSP); 30 ft, Singapore: Boring in coral rocks, Palau Salu (W AM). m W of Fort George, St. George (ANSP). Vi Philippines: Boring in dead coral, Apat Bay, Calauage St. Lucia\ Boat Harbour, Castries (MCZ); Marigot Bay, S. Quezon (WAM); 15 fms, N of Laminusa Is., Harbour (MCZ). Siasi, Sulu (WAM); 1 fm, dead coral, Laguio Pt., Jamaica: (Type locality): Lister (1687); (M CZ). Lopez Bay, S. Quezon (WAM). Mexico: 25 fms, off Cape Catoche, Yucatan (USNM). Taiwan: (W en-Lung W u, 1980). Curacao: 30 ft, Oranjestad Lagoon, Aruba I. (ANSP). Okinawa: Ryuku Is. (ANSP). Panama: 10 fms Limon Bay (CAS). 10 fms, 2 m. off Japan: Shigeo Hashimoto, Kii (ANSP). Colon (MCZ). People’s Republic o f China: Coast of Guandong to British Honduras: Punta Gorda (ANSP); 12 ft, reef E Hainan I. (Tsi & M a, 1980). of Cangreja Cay (ANSP). Solomon Islands: 180 ft. boring in dead coral boulders, Venezuela: Isla Tortuga (Soot-Ryen 1955). W side of M alapaina I., SE San Cristobal (W AM). Brazil: 20 fms, off Cuba Sao Roque 6°59'S, 34°47'W New Caledonia: 0-10 ft, Baie de l’Orphelinat, Noumea (USNM). (ANSP); Recaudy Reef, Noumea (ANSP); 50 ft, 3 mi NE Dunebea Pass (ANSP); 0-18 ft, Santa Marie (Isle E astern P a cific Ngea), M agenta (ANSP). Mexico: Boring in Ostrea iridescens, Punta Camaron, Fiji: (ANSP, MCZ, CAS). M azatlan (SDNHM ). M azatlan (CAS); 5-10 fms, M aria M adre Is., Tres M arias Group (CAS). Society Islands: Fauni Pt., Bora Bora (USNM). Tuomotu Archipelago: 10 fms, coral rocks, Rangiroa I ndo -W est P a cific Lagoon (WAM); Ngarumaoa Is., Raroia (USNM); Madagascar: 0-5 ft, E of Nosy Ambariole, SE of Nossi Tatau I. (USNM). Be (ANSP); 16 fms, 2-3 mi S of Nosy Iranja, 32 mi. SW of Nossi Be (ANSP); 0.6 ft, E Bay between Nosy Am ­ Marquesas: 37-40 fms, W of Fatu Hiva (USNM). bariole & Nosy Ambariotelo, SE of Nossi Be (ANSP); Pitcairn I.: 40-58 fms (USNM). 0.8 ft, Pointe Lokobe, SE Nossi Be (ANSP); 0.6 ft, lies Australia: Northern Territory: Darwin (Tate 1892). Radam a, 52 mi S of Nossi Be (ANSP). Queensland: Torres Strait (Melville & Standen, 1899); Kenya: Shimoni (MBNH). 3 m, in dead Porites, W atson Bay, Lizard I. (W AM ); in Mauritius: MNHN (Paris); (BMNH); 0.8 ft, Pointe dead coral, Rocky Point, Lizard I. (WAM); reef flat, Fayette (ANSP); Blue Bay (ANSP). Low Isles (W AM , AM); Britom art Reef (NMV); South Keppel I. (W AM ); in dead coral, outer reef rim and reef Aldabra: (BMNH). crest, Heron I. (W AM); 4 m, reef-front slope, in de ad Seychelles: (BMNH); 30-36 ft, Cerf I., NE Mahe coral, Heron I. (WAM); boring in beach-rock, south (ANSP); 18 ft, St. Anne I., NE Mahe (ANSP). side of H eron I. (NM V). Western Australia (All W AM ): Zanzibar: (BMNH); 11-12 fms, Pwakuu I. (ANSP); Upper intertidal zone, boring in oyster shells, Der by; 11 fms, 1 mi W . Nyange I. (ANSP); 5-8 fms, 3 mi. SE 22 fms, 40 mi. W of Cape Jaubert; oyster shells, up per Bawi I. (ANSP); 0-6 ft, Chumbe I. (ANSP). intertidal zone, Kendrew I., Dampier Arch; dead cor al rocks, reef ridge, Kendrew I., Dampier Arch; 3 m, Red Sea: Eilat (WAM); Djibouti and Aden (Lamy, Rosemary I., Dampier Arch; 10 mi, S of Exmouth, Ex­ 1937); Ghardaga (Gohar & Soliman 1963). mouth Gulf; 18 m, shell, coral rubble & lithotham nion Aden: (BMNH). nodules, 5 km ESE of Cape Heirisson, Shark Bay; ree f Iran: Gadani, E of Samniani, Baluchistan (BMNH). flat, Long I. Passage, Abrolhos; 15 m, 24 km N of Pakistan: Ibrahim Maidari, near Karachi (BMNH); Dongara; 82.3 m, 35 km W of Jurien Bay; Mosman Karachi (CAS). Beach & Hall Bank, Fremantle; 11-17 m, off Fremantle; 10 fms, 1/2 m W of south end of Garden I.; 54 ft, India: Hare I., 6 mi SW M andapam, Gulf of M annar Dunsborough, Geographe Bay; 46 m, in dead coral, (ANSP); Bombay (MCZ, BMNH). Cheyne Beach. Sri Lanka: Pearl Banks, Gulf of M annar (BMNH).

Burma: Arakan and Mergui (BMNH). ACKNOWLEDGEMENTS Thailand: Kata, near Khao Lan, Phuket I. (ANSP); W e acknowledge with thanks financial support from M utapone I., Chumpon (MCZ); 1-30 fathoms in old the National M useum of Victoria Council for field w ork coral blocks, Cape Liant to Koh Chang (Lynge 1909). and technical assistance, and facilities provided b y the Nicobar Islands: (Lynge 1909). California Academy of Sciences during the drafting of the manuscript. Financial support for travel to Eur o­ M ergui Archipelago: (Lynge 1909). pean and American museums was generously provided Maldive Archipelago: Addu Atoll (BMNH); Suvadiva by the Ian Potter Foundation of Melbourne. We are A toll (Lynge, 1909). particularly grateful to Professor J. V. Hurley and M r. Malaysia: Palau Bidang, N of Penang (BMNH). Dennis Cahill of the Departm ent of Pathology, Unive r­ 124 B. R. WILSON AND RICHARD TAIT

sity of M elbourne, who gave kind permission to use the K ellogg , J. L., 1915. Ciliary mechanism s of lam ellibranchs facilities of their department. The staff of the Ce ntral with descriptions of anatom y. J. M orph. 26: 625-701. Laboratory, Department of Pathology also provided K leeman , K . H ., 1980. Boring bivalves and their host corals valuable advice on histological work. M r. Jack Smith, from the Great Barrier Reef. J. M oll. Stud. 46: 13-54. L amarck , J. B. d e , 1819. H istoire N aturelle des A nim auxsans Department of Pathology took the photomicrographs Vertebres Vol. 6, N o. 1. Paris, 333p. and Mr. Frank Coffa of the National Museum of Vic­ L amy , E., 1937. Revision des M ytilidae vivants du M useum toria photographed the shell specimens. Thanks are also National d’Histoire Naturelle de Paris. J. conch., due to staff of many museums who spent much time Paris. 81: 5-71 preparing loans of specimens in their custody. Dr. L ightfoot , J., 1786. A catalogue o f the Portland M useum . . . Michael Ghiselin and Dr Vida Carm en Kenk kindly rea d London, pp. viii + 194. and criticized the early drafts of the manuscript. L in k , H. F., 1806-08. Beschreibung der Naturalien-Sam m lung der U niversitat zu R ostock. Rostok.

L i ster , M ., 1687. Historiae sive Synopsis methodicae Conchyliorum . 3, figs. 1(161 )-288(445). London. REFERENCES L ynge , H ., 1909. The Danish Expedition to Siam 1899-1900,

A t k in s , D ., 1937. On the ciliary m echanism s and interrelati on­ IV. M arine Lam ellibranchiata. M&moires. Academ ie ships of lam ellibranchs. Pt. 3. Types of lam ellibra nch royale des sciences et des lettres de Danemark. gills and their food currents. Q. Jl m icrosc. Sci. 79: Copenhagen, set. 7, Section des Sciences 5(3): 100-207.

375-421. M elville , M . A. & S tanden , R ., 1899. Report on the marine

B erry , S. S., 1959. Notices of new eastern Pacific M ollusca obtained during the first expedition of Pr of. M ollusca — III. Leaf!. M alac. 1(18): 108-113. A. Haddon to the Torres Straits in 1888-89. J. Linn.

C arazzi , D ., 1903. C ontributo all’istologia e alia fisiologia de i Soc. 27: 150-206.

lamellibranchi. 3. Come si scavano il nicchio i M oore , E. I., 1983. Tertiary marine pelecypods of Californ ia Lam ellibranchi perforanti? Int. M schr. A nat. Physiol. and Baja California: Nuculidae through M alleidae. 20: 57-73. U.S. Geol. Survey Prof. Paper. 1228-A: A 1-A 108.

C hemnitz , J. H ., 1785. In N eues system atisches Conchylien- M orch , O. A . L., 1853. Catalogus Conchyliorum quae reliquit Cabinet, F . H . W . M artini & J. H . Chem nitz, 8: 1-372. D. A lphonso d ’Aguirra & Gadea com es de Yoldi. Fasc.

D all , W . H, 1898. Contributions to the Tertiary fauna of secundus. Acephala. Klein, Hafniae (Copenhagen), Florida. Trans. W agner free Inst. Sci. Phiiad. 3: 1-75.

571-947. M orton , B., 1973. Some aspects of the biology and func­

D all , W . H ., B art sch , P. & R eh der , H. A ., 1938. A M anual tional m orphology of feeding and digestion of Lim - of the recent and fossil m arine pelecypod m ollusks of noperna fortunei (Dunker) (Bivalvia: M ytilacea). the H awaiian Islands. Bull. Bernice P. Bishop M us. M alacologia. 12: 265-281.

153: 233 pp. M orton , B. & S cott , P. J. B ., 1980. M orphological and func­

F ankboner , P. V ., 1971. The ciliary currents associated with tional specializations of the shell, musculature an d feeding, digestion and sediment removal in Adula pallial glands in the Lithophaginae (Mollusca: (Botula) fatcata Gould, 1851. Biol. Bull. mar. biol. Bivalvia). J. Zool., Lond. 192: 179-203.

Lab., W oods Hole. 140: 28-45. M owry , R. W ., 1956. Alcian blue techniques for the

F ranc , A ., 1960. Classes des bivalves. In Treate de Zoologie, histochemical study of acidic carbohydrates. J. P-P. Grasse, ed., Paris: Masson, Paris, 5(2): H istochem . Cytochem . 4: 407.

1845-2133. P elseneek , P., 1911. Les Lam ellibranches de l’expedition du

F r enei x , S. & G oro d isk i , A ., 1963. Bivalves Eocenes du Siboga, Partie anatom ique. Siboga Exped. 53a: 1-125.

Senegal, Prem iere Part. M im . Bur. Rech. geol. mini'er. P ot iez , V. L. V. & M ichaud , A. L. G ., 1844. Galerie des 17: 1-123. M ollusques, ou catalogue m ethodique, descriptif et

G melin , C. S., 1791. In System aN aturae, C. Linnaeus, revised raisonne des mollusques et coquilles du museum de 13th ed. Lipsiae, vol. I, pt. 6, pp. 3021-3910. Douai. J. B. Bailliere, Paris. 2 vols.

G ohar , H. A. F. & S oliman , G . N ., 1963. On two mytilids S chreiber s , K. F. A. von , 1793. Versuch einer vollstandigen boring in dead coral. Pubis mar. biol. Stn Ghardaqa. Conchylien-Kenntniss nach Linne’s System. 2 vols, 12: 205-218. W ien.

G orea u , T. F ., G orea u , N. L, S oot -R yen , T. & Y onge , C. S oot -R yen , T., 1955. A report on the family Mytilidae M ., 1969. On a new commensal mytilid (M ollusca: (Pelecypoda). Allan H ancock Pacific Expeditions. Bivalva) opening into the coelenteron of Fungia 20(1): 1-175.

scutaria (Coelenterata). J. Zool., Lond. 158: 171-195. S oot -R yen , T ., 1969. Super fam ily M ytilacea. In Treatise on

G orea u , T. F ., G orea u , N . I. & Y onge , C. M ., 1972. On the Invertebrate palaeontology, Part N , M ollusca 1, R . C. mode of boring in Fungiacara eilatensis (Bivalvia: M oore, ed., Geological Society of America and M ytilidae). J. Zool., Lond. 166: 55-60. University of Kansas Press, Boulder, Colorado and

I r e dale , T ., 1939. M ollusca, Pt. 1. Scient. Rep. G t Barrier Lawrence, Kansas, N 271-280.

R eef Exped. 5(6): 209-425. T ate , R ., 1892. Descriptions of som e new species of marine

J accarini , V ., B anni ster , W . H ., & M icallef , H ., 1968. The M ollusca from Australia. Trans. R. Soc. S. A ust. 15: pallial glands and rock-boring in Lithophaga 125-132.

lithophaga (Lam ellibranchia, M ytilidae). J. Zool., Tsi, C. Y. & M a , S. T., 1980. A preliminary checklist of the Lond. 154: 397-401. marine gastropod and Bivalvia (M ollusca) of Hong

K een , A . M ., 1937. A n abridged check list and bibliography o f Kong and southern China. In Proceedings. First Inter­ West North American marine Mollusca. Stanford national M arine Biological W orkshop: The M arine University Press. Flora and Fauna o f H ong Kong and Southern China,

K een , A . M ., 1971. Sea Shells o f Tropical W est A m erica. Stan­ B. S. M orton and C. K. Teng, eds, H ong Kong Univer­ ford University Press. sity Press: 431-458. MYTILID BIVALVE BOTULA 125

T urner , R. D. & Boss, K. J., 1962. The genus Lithophaga in southern Australia. Proc. malac. Soc. Lond. 37: the W estern A tlantic. Johnsonia. 4(41): 81-116. 279-95.

W aller , T. R., 1983. Dahllite in the periostracum of W il son , B. R., 1979. A revision of Queensland lithophagine Lithophaga nigra (M ollusca: Bivalvia) and its taxo­ mussels (Bivalvia: M ytilidae: Lithophaginae). Rec. nomic and functional im plications. Amer. M alaco- Aust. M us. 32: 435-489.

logical Bull. 1: 101. Y onge , C. M ., 1955. Adaptation to rock-boring in Botula and W en -L ung W u , 1980. The list of Taiwan bivalve fauna. Q. Lithophaga (Lamellibranchia, Mytilidae) with a J! Taiwan M us. 33: 55-208. discussion on the evolution of this habit. Q. Jl m icrosc. W il son , B. R ., 1967. A new generic nam e for three recent an d Sci. 96: 383-410. one fossil species of M ytilidae (M ollusca: Bivalvia ) in

B