Phuhet Marine Biological Center Special Publication 21(3): 595-601 (2000) 595

SI{ALLOW -WATER "ARCIIAEOGA,STROPODS" OFSOUTH-EAST ASIA: AN INTRODUCTION

Richard Kilburn

Natal Museum South Africa Tropical Marine Mollusc Progratnrne (TMMP) 596

INTRODUCTION Order Superfamily Pleurotomarioidea The term "archaeogastropod" is here used Family Pleurotomariidae [not covered] only as a convenient way of grouping to- Superfamily Scissurelloidea gether the more primitive prosobranch fami- Family Scissurellidae [not covered] lies. Modern systematic techniques have led Superfamily Haliotoidea to the families of the old order "Archaeo- Family Haliotidae " to be redistributed into three Superfamily Fissurelloidea different orders (in two different subclasses). Family Among the characters found in different Superfamily archaeogastropod families (no family has all Familv Turbinidae of them) are a nacreous shell interior, a lim- Family pet like-form, a rounded aperture without a Family Skeneidae lnot covered] distinct anterior canal and a horny opercu- lum of many spiral turns (in some calcare- Onopn Npnrropswa ous or with few turns). Paired gills occur in Superfamily some, and are often associated with a slit, Family hole or series of holes in the shell, which Family Neritopsidae serve for the expulsion of stale water. At the Family Phenacolepadidae other extreme, some of the families have lost true gills and use a ring of mantle tentacles called pallial gills for respiration. SUMMARY OF THE MAIN The typically bears numerous teeth ARCIIAEOGASTROPOD in each row (the rhipidoglossate state) or FAMILIES REPRESENTED only a few greatly strengthened, hook-like IN S. E. ASIA: teeth per row (the docoglossate radula) Archaeogastropods are mainly grazers, us- ing the powerful radula to scrape algae off ORDER rock surfaces. Others use the same feeding method to eat sponges or coelenterates. The Patellogastropoda is now regarded as the most primitive group of living gastro- pods and is in fact the sister group ofother Outline classification prosobranchs. It contains the "true" , "Archaeogastropod"farnilies (mainlyaf- with a saucer-shaped shell and a broad foot, ter Sasaki, T. 1998. Comparative anatomy both adaptations to clinging firmly to hard and phylogeny of the Recent Archaeo- surfaces. The limpet shape is secondary and gastropoda, Bulletin of the Uniuersity Mu- a similar shell has evolved in various unre- setlm, Uniuersity of Tolzyo 38:7-224): lated caenogastropod and even pulmonate and opisthobranch families. The protoconch SUBCLASS EOGASTROPODA is symmetrical and jar-shaped instead of Ononn PlrnllocesrRoPoDA spirally coiled. Other patellogastropod char- Suborder Patellina acteristics include a docoglossate radula that Superfamily bends over the odontophore in a straight Family plane, so that the side teeth do not spread Family out, and teeth that are strengthened with Superfamily Acmaeoidea iron oxide. The three Asian families differ Family Lottiidae mainly in shell crystalline structure, radula Subclass Orthogastropoda and anatomy. Phuhet Marine Biological Center Special Publication 21(3): 595-601 (2000) 597

Family PATELLIDAE: family Acmaeidae in older literature. Al- In these limpets the interior of the shell is though the shell resembles that of the shiny, occasionally silky, but never peariy. Patellidae, the mantle cavity in the Lottiidae True gills are absent, but there is a ring of is unique in retaining a gill (in some genera pallial gills. They are grazers on lichens and pallial gills are also present). The common- encrusting algae, often on wave-battered est in S. E. Asia is , with at rocks. OnIy a single genus and oc- least a dozen species. curs in the region, namely flexuosa (previously referred to genus Po- tella). This species has a distinctively ORDER VETIGASTROPODA irregular shell edge (which will This is a large and very diverse group, re- distinguish sembling the Neritopsina in the rhipido- it from glossate radula, but differing in a wide range superficially of anatomical details, such as the presence similar ofepipodial tentacles and sense organs. members of family Lottiidae). It appears to form a home-scar SUPERFAMILY HALIOTOIDEA to on the rock, which it returns A single family is recognised. after feeding. Family IIALIOTIDAE Family NACELLIDAE The well-known abalones have an ear- The shell in this family resembles that of shaped shell with a very large, nacreous members of the Patellidae and Lottiidae, but aperture and a greatly reduced spire. From its interior is pearly or silver (resulting from various genera in the Trochidae which have the foliated crystalline structure). External similar shaped shells, abalones may be eas- sculpture is much weaker than in ily distinguished by having a series of 5-8 Scutellq.stra flexuosa (Patellidae). OnIy pal- holes (tremata), which serve for both intake lial gills are present. A single genus, , and expulsion of water currents. Both gills occurs in S. E. Asia, with 5-6 species, sev- are retained. eral of which may A single genus live at different Haliotis, with Ievels on the rather few species, same shore. is recognised. The larger and. commoner specres are widely eaten Patelloida and are important testudinaria in mariculture.

Family LOTTIIDAE: Haliotis ouina Members of this family were referred to the (TMMP) 598 Tlopical Marine Mollusc Programrne

SUPERFAMILY FISSURELLOIDEA SUPERFAMILY TROCHOIDEA

Limpet-shaped with an apical hole or ante- Shell more or less conical (sometimes with rior slit in the shell, for the expulsion ofstale a low spire and huge aperture), without a water; interior never nacreous. Mantle slit or perforations, interior almost always sometimes covering shell. A pair of gil1s is nacreous, operculum calcareous or corneous present. (horny). Right gill lost; epipodium with sen- sory tentacles and papillae, neck with lobes FamiIyFISSURELLIDAE : that serve to direct currents in and out of Characters as given above. Two subfamilies the mantle cavity. Mainly herbivores, graz- of "keyhole limpets" are recognised, sepa- ing on algae and lichens, but with some ex- rated mainly by the number of cusps on the ceptions. outer lateral teeth ofthe radula. These are (a) subfamily s.s., which con- tains genera such as Diodoro and FamilyTURBINIDAE: , inwhich the apex is replaced Members of this family are more or less top- by a hole (small in the former, very long in shaped, with an aperture that is usually cir- the latter), and (b) subfamily cular (with a continuous margin), and an , which contains genera with operculum that is (with rare exceptions) cal- an intact apex such as Emarginula and careous, with a long growing edge. "Turban Emarginello (both shells" live mainly subtidally and in pools, with a deep anterior hiding under rocks or coral by day. They sliL), Hemitoma and ar e gr azing herbivores. Clypidina (both with Seven subfamilies are currently recognised, a shallow notch), the main ones being as follows: andTfu.gali and Scutus Subfamily Turbininae : Shell thick, small (in which there is only to large, juvenile whorls with a double an- a shallow indent gle; operculum thick and heavily calcified, in the anterior margin partly sunken into surface of foot of the shell). Most (metapodium). Main genera: Tfu,rbo, Bolma, live subtidally in Astraea. crevices and under rocks or coral, apparently feeding mainly on sponges, although some are Scutus unguis omnivores.

Emarginula Tltrbo argyrostoma funiculata sibogai Phuhet Marine Biological center special publication 21(J): s9s-601 (2000) 599

ferred to subfamily Tricoliinae.

Astrqea calcctr

Phosianella solida Subfamily Liotiinae : Small to minute shells, aperture margin continuous, circu- Iar; operculum corneous with calcareous granules, not partly enclosed in the foot, periostracum calcified, shell usually axially FAMILYTROCHIDAE: ribbed, outer lip often thick. There are many Shell with a wide range of shapes, usually genera, all poorly studied, such as Liotina top-shaped or globular, some ear-shaped, the and Bathyliotina. operculum corneous with a short growing edge; rachidian plate ofradula without sup- SubfamilyAngariinae : These resemble gi- porting flange. Found in a range of habi- ant liotiines, but have a corneous opercu- tats, from exposed intertidal rocks to ma- lum. They have very ornate sculpture, usu- rine grasses and sandy bottoms. Mainly ally with prominent scales or spines. There grazers on algae or sponges, but a few are is a single gen:us, Angaria,l.argelv restricted carnivorous (eating coelenterates or even to South-East Asia and tropical Australia, other molluscs) or filter-feeders. Iiving subtidally on coral.

Angaria lacinata

TYochus mq,culatus Subfamily Phasianellinae : Shell elongate with a raised spire, glossy, brightly pat- Seven subfamilies of Trochidae occur in S. terned surface with fine lines of dark and E. Asia, but as these groups are based on Iight dots, a weak ridge in parietal region details of radula and soft anatomy, they are supporting operculum; interior not nacreous, not dealt with here. operculum thick, convex. A single genus, To illustrate the diversity of the family in a Phasianella, with only a few species, which practical way, the commoner trochid genera live on seaweeds and sea grasses. The tiny can be divided into the following artificial species of the genus TYicolia, although very groups based mainly on shell characters. similar, have shell pigments that fluoresce Examples of some of the commoner genera under ultra-violet light, and are now re- in each group are given. Tlopical Marine Mollusc Programme (TMMP) 600

(A) APERTURE VERY LARGE, (b) without teeth: SPIRE SMALL, OPERCULUM (1) Conical: Trochus, Calliostoma, REDUCED OR ABSENT: Jujubinus. (2) Globulaq with rounded whorls and low Body much larger than shell in some: gen- spire; mostly small: Gibbula, Ethalia, er a Stomq.tia, P seudostomatella, Stomqtella Monilea, Umbonium., Ethminolia, Chryso- (syn. Gena), Stomatia. stoma.

Stomatella Umbonium planulata giganteum

ORDER NERITOPSINA

This group had an earlier origin than the Vetigastropoda, and unlike other archaeogastropods has shown a diverse ra- diation into freshwater and moist terrestrial habitats (two families, the Hydrocenidae P s e u do s to mat ella p clp y r ac e cr and Helicinidae are entirely terrestrial). This is partly the result of the development of internal fertiiization.The interior of the (B) APERTURE NORMAL-SIZED: shell is not nacreous, and the operculum is calcareous, usually with a peg-like projec- (a) Columella with one or more tion that locks under the inner lip. They lack distinct teeth: the epipodial sense organs and tentacles of (1) Shell conical, outer lip smooth inside: the Veitgastropoda. Tectus. (2) Globular, or conical with a rounded pe- riphery, outer lip ridged inside: Euchelus, FamilyNERITIDAE: Clanculus, Monodonta. Mostly globular shells, with semicircular aperture, and an inner lip covered by a thick callus "shield", its edge often toothed; the whorls are reabsorbed internally to provide maximum space for water-storage; opercu- Ium with a distinctive peg on its inner edge. Often attach large numbers of cap-shaped white egg-capsules to the surrounding rocks and to other shells. Grazers, feeding on al- gae and deposits of diatoms.

Monodonta Three subfamilies are recognised: labio SubfamilyNeritinae : Phuket Marine Biological Center Special Publication 21(S): 595-60l (2000) 601

Medium-sized, usually sculptured; outer lip inner lip is not covered by a callus shield often thick. A single marine genus Nerita, and its aperture edge has a wide, square which has no periostracum, and an outer lip indent; the inner whorls are not resorbed; that is usually toothed. Various species of operculum with a wide, square projection on Nerita are common elements on exposed its inner edge. There is a single Asian spe- rocky shores, living at mid to high-tide lev- cies, Neritopsis radula, which is rarely seen els. A few live on mangroves. In fresh-wa- alive as it appears to live mainly in under- ter habitats Nerita is replaced by genera water caves. such as Neritinq and Clithou in these the periostracum is thick, often shiny and brightly patterned, outer lip thin and smooth inside. Some Clithozz species have external knobs or spines. A related genus, Neritodryas, has invaded the land, climbing onto vegetation along river banks.

Neritopsis radula Neritq polita Family PHENACOLEPADIDAE : Shell limpet-Iike with a curved apex, sculp- ture of fine radial ribs, internally sometimes Subfamily Smaragdiinae : with a feeble septum; operculum vestigial. Small, smooth, shiny, outer lip thin; often A poorly-studied family, apparently living brightly coloured. Lives on marine grasses mainly under rocks in oxygen-poor habitats on sheltered mudflats. The only common (an adaptation is the presence of haemo- genus is Smaragdia. globin in their blood). Probably a single ge- nus, Plesiothyreus (synonym ) Subfamily Septariinae: These are very unusual limpet-Iike nerites with the shell apex at or near the posterior end, the underside with a septum (Iike the "mesogastropod" genus C repidula), exterior smooth, operculum a simple flat plate. The single genus Septaria is adapted to living in fast-flowing streams, even waterfalls.

Family NERITOPSIDAE: Sheli similar to that of Neritidae, but the Plesiothyreus cytherae