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Home , Irus (bivalve), Macoma, Pallial sinus

Macoma inquinata Phylum: Class: ; Order: Veneroida Irus clam Family:

Taxonomy: Macoma balthica, M. nasuta and have short lateral (when present – M. inquinata were all originally described as see Possible Misidentifications), shells with members of the genus Tellina. Tellina external striations or ribs, and deep pallial inquinata and T. irus, initially described as sinuses (Coan and Valentich-Scott 2007). different species (the former with eastern When holding closed shell in both hands with Pacific distribution, the latter with western), the hinged area up and the ligaments toward were synonymized in the genus you, the right is in the right hand (Fig. 4) Heteromacoma. Later, this synonymization (Keen and Coan 1974). was reversed based on characters of shell Body: morphology and Macoma inquinata Color: (previously, and confusingly, called M. irus) Interior: is long, strong, was deemed a member of the genus narrow, and prominent (Figs. 1, 4). It is not Macoma, with an eastern Pacific distribution seated on a nymph, but is entirely external while H. irus, remained a Heteromacoma, with (Tellinidae, Coan and Valentich-Scott 2007). a the western Pacific (see Keen 1962; Coan Exterior: 1971). Thus, known synonyms for M. : inquinata include T. inquinata as well as M. Gills: irus. Subspecific designations are also Shell: Shape ovate or subovate, but not sometimes seen (e.g. Macoma circular. Posterior end is narrower and less heteromacoma inquinata, Kabat and O’Foighil rounded than anterior end. Shell is heavy, 1987). Macoma inquinata is the name almost not fragile and inflated, with subcentral exclusively used in current intertidal guides umbones (Fig. 1). Occasionally, there is a (e.g. Coan and Valentich-Scott 2007). slight gape and flex to right on the posterior end (Dunnill and Ellis 1969). Description Interior: is not detached Size: Individuals up to 55 mm in length from the anterior ventral end of pallial sinus (Coan 1971). The illustrated specimen (Fig. (Fig. 2) and is longer in the left valve (Fig. 3). 1) is 44 mm in length, 35 mm in height, and The pallial sinus reaches almost to the 18 mm in diameter. anterior adductor scar, or just to its base in Color: Shell is dull white, with a dark and the left valve (Fig. 3) (Coan 1971). The pallial opaque (not shiny) (see Fig. sinuses are similar in the two valves (e.g. 294, Kozloff 1993). Interior shell is compare to M. nasuta, this guide). porcellanous white and feebly polished Exterior: External shell bears (Dunnill and Ellis 1969). Siphons are only conspicuous concentric sculptural undulations barely yellowish in color (Kozloff 1993). (Fig. 1). General Morphology: Bivalve mollusks are Hinge: Hinge with ligament is entirely bilaterally symmetrical with two lateral valves external and no lateral teeth (Macoma, Coan or shells that are hinged dorsally and and Valentich-Scott 2007). Hinge area surround a , head, foot and viscera includes two cardinal teeth in each valve, but (see Plate 393B, Coan and Valentich-Scott no lateral teeth (Fig. 5). 2007). Among the bivalves, the Heterodonta Eyes: are characterized by ctenidia (or gills) that Foot: are eulamellibranchiate, fused mantle Siphons: The inhalant and exhalant siphons margins and the presence of long siphons. are completely separate (Fig. 1a) (Quayle Veneroid bivalves have well-developed hinge 1970; Kozloff 1993). teeth and members of the family Tellinidae Burrow:

Hiebert, T.C. 2015. Macoma inquinata. In: Oregon Estuarine Invertebrates: Rudys' Illustrated Guide to Common Species, 3rd ed. T.C. Hiebert, B.A. Butler and A.L. Shanks (eds.). University of Oregon Libraries and Oregon Institute of Marine Biology, Charleston, OR.

A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12908 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] Possible Misidentifications sand clam and has a quadrate and truncate Tellinids can be distinguished from posterior. The latter is elongate, has a other small or young bay clams (i.e. pointed posterior, unique muscle scars, is Mactridae: Tresus; : Protothaca, relatively rare and small (to 2.5 cm) and Saxidomus; Myidae: Mya, Cryptomya) an occurs from Trinidad, California southward. external ligament, an ovate shell, an Macoma secta, also has a white shell, with a inconspicuous nymph (or supporting yellowish epidermis. Its right valve is more projection for the external ligament), inflated than the left, and it can be large (to sometimes reddish hue and lateral teeth as 120 mm) and is more common in clean sand, well as a shell with ribs or striations (no radial not in estuarine mud. pattern) and shells that never gape. Lateral The morphology of the pallial sinus teeth may or may not be present in the differentiates the other species. In species Tellinidae (Coan 1971). Myids have a hinge without a posterior dorsal flange, M. acolasta with a spoon-shaped chondrophore (left and M. yoldiformis, the anterior ventral edge valve) and a projecting tooth (right valve) (see of the pallial sinus is detached for a portion of Mya arenaria, this guide). Venerids have the distance to the posterior adductor muscle three cardinal teeth in each valve. Mactrids scar. Macoma acolasta also has a rounded have an internal ligament, A-shaped cardinal posterior, rather than pointed as in M. teeth, and gaping valves (Coan and yoldiformis and is rare, sand-dwelling, and Valentich-Scott 2007). The Tellinidae has occurs from Bodega Bay, California, around 16 species distributed between two southward. Macoma yoldiformis is elongate, genera locally – Tellina and Macoma. These inflated, and thin, with the pallial sinus genera can be differentiated by the hinge detached from the pallial line. Although the teeth, Tellina species have a hinge with range of this clam is from Vancouver south to lateral teeth, while Macoma species do not. Baja California, it is not included in Puget Macoma species have shells that are also Sound or British Columbia work (Dunnill and more rounded and inflated thanTellina, and Ellis 1969). It can be found in silt in low are smooth, white, often chalky. They are intertidal of protected bays (Coan and characterized by having a ovate shell Valentich-Scott 2007). consisting of two equal valves, a dark and Macoma inquinata, M. nasuta and M. deciduous periostracum, two cardinal teeth, balthica (see descriptions in this guide) are all the absence of lateral teeth and a pallial sinus species with an anterior ventral edge of pallial that is deeper on the left valve (Scott and sinus that is not detached and they tend to be Blake 1998; Arruda and Domaneschi 2005). larger (up to 110 mm) than M. acolasta or M. Macoma species may also have a more yoldiformis (less than 30 mm). Macoma northern geographic distribution whileTellina balthica has a pinkish hue and a pallial sinus are elongate, relatively compressed, that ends ¾ of the way to anterior adductor conspicuously sculptured, brightly colored, muscle scar and is generally more oval than and usually warm water dwellers (Coan M. nasuta or M. inquinata (Kozloff 1993). In 1971). Eleven species in the infaunal genus M. inquinata, the pallial sinus does not reach Macoma (Luttikhuizen et al. 2012) are the ventral end of the anterior adductor reported locally (although 30 have been muscle. , on the other hand, identified in the northeastern Pacific, Dunnill is not as round and heavy as M. inquinata and Ellis 1969), but only seven are described and its pallial sinus reaches and joins the in local keys (e.g. Coan and Valentich-Scott anterior adductor scar above its base (left 2007), the four most common species of valve). (Its right valve may be more like M. Macoma in our area are M. balthica, M. inquinata’s). Furthermore, its siphons are nasuta, M. inquinata, and M. secta (Kabat orange and its shell posterior is bent to the and O’Foighil 1987). right (hence the name, bent-nose clam). Two species, M. secta and M. Macoma inquinata can also bend slightly indentata have a posterior dorsal flange posteriorly, and may be confused with the extending from posterior end to the external thinner M. nasuta, without investigations of ligament, this is absent in other Macoma the other aforementioned features. In M. species. The former species is called the the balthica, the pallial sinus that reaches to 1/4 Hiebert, T.C. 2015. Macoma inquinata. In: Oregon Estuarine Invertebrates: Rudys' Illustrated Guide to Common Species, 3rd ed. T.C. Hiebert, B.A. Butler and A.L. Shanks (eds.). University of Oregon Libraries and Oregon Institute of Marine Biology, Charleston, OR. the anterior adductor muscle scar and the Temperature: Cold to temperate waters. shell has a pinkish hue. (see Plate 422 for The presence of M. inquinata in the fossil diagrams of these distinguishing record at Newport Bay, California during the characteristics in Macoma). late Pleistocene suggests historically cooler Macoma incongrua, generally a temperatures in that region (Powell 2001). northern species, is the species closest to M. Tidal Level: Intertidal and subtidal (Kabat inquinata. It can be found intertidally to 36 and O’Foighil 1987) to 48 m offshore (Coan meters. It is quite circular in outline, its pallial 1971). sinuses extend longer than in M. inquinata, Associates: Often co-occurs with the and are different between its two valves, they congener, M. nasuta (South Slough of Coos are similar in M. inquinata's valves. Macoma Bay). Juvenile pea crabs, Pinnixia littoralis, incongrua averages 30–40 mm in length can occur within the mantle cavity of M. (Dunnill and Ellis 1969). inquinata and M. nasuta in Puget Sound, (The following species may be present Washington (Haderlie and Abbott 1980). locally, but are not included in local Abundance: Common in bays (Kozloff 1993; dichotomous keys). Macoma expansa, is a Coan and Valentich-Scott 2007) and can be rare, usually offshore species (to 50 mm) locally abundant (e.g. over 6 million at one whose pallial sinuses are perpendicular to the small Coos Bay site, Gaumer 1978). Macoma pallial line. Macoma elimata is found only in inquinata was one of the dominant intertidal 15–476 meters of water. Macoma calcarea is macrobenthic species in the Chukchi Sea found from 35 meters and lower, from 37° (67–73˚N, Wang et al. 2014). north. Other northern subtidal species include the large M. brota and M. lipara Life-History Information (Dunnill and Ellis 1969). Reproduction: Separate sexes, gametes are discharged into the water through excurrent Ecological Information . Gametogenesis for M. nasuta and M. Range: Type locality is Columbia River, OR secta is described by Rae (1978), with both (Keen 1962). Known range includes Siberia, species ripe with gametes in summer months Aleutian Islands, British Columbia, south to (Tomales Bay, California). The reproduction Oregon and rare further south of Santa and development has been described for the Barbara, California (Coan 1971). common congener, M. balthica (Caddy 1967, Local Distribution: Distribution in many 1969; Lammens 1967), which spawns in Oregon bays, particularly Tillamook, Coos, spring and summer (Friday Harbor, Siuslaw, Yaquina, and less common in Alsea, Washington, Kabat and O’Foighil 1987). Nestucca, Netarts Bays (Hancock 1979). Larva: Bivalve development generally Habitat: Usually in soft muddy sand (Dunnill proceeds from external fertilization via and Ellis 1969; Kabat and O’Foighil 1987) and broadcast spawning through a ciliate in protected areas. Individuals have also stage to a larva. Bivalve been found in coarse sand with shell hash, are characterized by a ciliated velum intertidal sand, and in fine sediment overlying that is used for swimming, feeding and flat rocks (British Columbia, Canada, Dunnill respiration. The veliger larva is also found in and Ellis 1969) as well as in eelgrass (Puget many gastropod larvae, but the larvae in the Sound, Washington, Kozloff 1974). Like other two groups can be recognized by shell Macoma species (e.g., M. nasuta), M. morphology (i.e. snail-like versus clam-like). inquinata individuals can be the subject of In bivalves, the initial shelled-larva is called a toxicity testing due to their uptake and D-stage or straight-hinge veliger due to the retention of benthic compounds by deposit “D” shaped shell. This initial shell is called a feeding. Macoma inquinata and other deposit I and is followed by a feeders accumulate more aromatic prodissoconch II, or shell that is subsequently hydrocarbons than suspension feeders (e.g., added to the initial shell zone (e.g. see M. Roesijadi et al. 1978; Crecelius et al. 1980; balthica, Fig. 1, Caddy 1969). Finally, shell Augenfeld et al. 1982). secreted following metamorphosis is simply Salinity: Individuals collected where salinity referred to as the dissoconch (see Fig. 2, is 30. Brink 2001). Once the larva develops a foot, A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12908 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected] usually just before metamorphosis and loss of (Lamellibranchiata). Canadian Journal the velum, it is called a pediveliger (Kabat and of Zoology. 47:609-617. O’Foighil 1987; Brink 2001). (For generalized 6. COAN, E. V. 1971. The Northwest life cycle see Fig. 1, Brink 2001). Macoma American Tellinidae. California balthica, M. nasuta and M. secta are all Malacozoological Society, Berkeley. known to have free swimming veliger larvae 7. COAN, E. V., and P. VALENTICH- (Marriage 1954; Rae 1978, 1979; Brink 2001). SCOTT. 2007. Bivalvia, p. 807-859. In: Juvenile: The Light and Smith manual: intertidal Longevity: invertebrates from central California to Growth Rate: Oregon. J. T. Carlton (ed.). University Food: Chiefly a deposit feeder (although also of California Press, Berkeley, CA. potentially a suspension feeder, see M. 8. CRECELIUS, E. A., J. M. nasuta and M. balthica, this guide), feeding AUGENFELD, D. L. WOODRUFF, and on surface bacteria and detritus with their J. W. ANDERSON. 1980. Uptake of siphons (Kabat and O’Foighil 1987). The trace metals by the clam Macoma feeding behavior of the congeners, M. nasuta inquinata from clean and oil- and M. inquinata showed variation in contaminated detritus. Bulletin of response to water flow. Their inhalant Environmental Contamination and siphons extended farther, allowing for deposit Toxicology. 25:337-344. feeding over a larger area, when water flow 9. DUNNILL, R. M., and D. V. ELLIS. was lower (Levinton 1991). 1969. Recent species of the genus Predators: Shorebirds. Macoma (Pelecypoda) in British Columbia. National Museum of Bibliography Canada, National Historical Papers. 45:1-34. 1. ARRUDA, E. P., and O. 10. GAUMER, T. F. 1978. Clam resources DOMANESCHI. 2005. New species of in a proposed Charleston boat basin Macoma (Bivalvia: : expansion site. Information report 78- Tellinidae) from southeastern Brazil, 1. Oregon Department of Fish and and with description of its gross Wildlife, Charleston, OR. anatomy. Zootaxa:13-22. 11. HADERLIE, E. C., and D. P. ABBOTT. 2. AUGENFELD, J. M., J. W. 1980. Bivalvia: the clams and allies, p. ANDERSON, R. G. RILEY, and B. L. 355-410. In: Intertidal invertebrates of THOMAS. 1982. The fate of California. R. H. Morris, D. P. Abbott, polyaromatic hydrocarbons in an and E. C. Haderlie (eds.). Stanford intertidal sediment exposure system: University Press, California. Bioavailability to Macoma inquinata 12. HANCOCK, D. R., T. F. GAUMER, G. (Mollusca, Pelecypoda) and B. WILLEKE, G. P. ROBART, and J. (Annelida, FLYNN. 1979. Subtidal clam Polychaeta). Marine Environmental populations: distribution, abundance, Research. 7:31-50. and ecology. Oregon State University, 3. BRINK, L. A. 2001. Mollusca: Bivalvia, Sea Grant College Program, Corvallis. p. 129-149. In: Identification guide to 13. KABAT, A. R., and D. O'FOIGHIL. larval marine invertebrates of the 1987. Phylum Mollusca, Class Pacific Northwest. A. Shanks (ed.). Bivalvia, p. 309-353. In: Reproduction Oregon State University Press, and development of marine Corvallis, OR. invertebrates of the northern Pacific 4. CADDY, J. F. 1967. Maturation of Coast. M. F. Strathmann (ed.). gametes and spawning in Macoma University of Washington Press, balthica (L.). Canadian Journal of Seattle, WA. Zoology. 45:955-965. 14. KEEN, A. M. 1962. Reinstatement of 5. —. 1969. Development of mantle the specific name Macoma inquinata organs, feeding, and locomotion in (Deshayes). Veliger. 4:161-161. postlarval Macoma balthica (L.) Hiebert, T.C. 2015. Macoma inquinata. In: Oregon Estuarine Invertebrates: Rudys' Illustrated Guide to Common Species, 3rd ed. T.C. Hiebert, B.A. Butler and A.L. Shanks (eds.). University of Oregon Libraries and Oregon Institute of Marine Biology, Charleston, OR. 15. KEEN, A. M., and E. COAN. 1974. (Mollusca, Bivalvia). Veliger. 21:384- Marine molluscan genera of western 399. North America: an illustrated key. 26. ROESIJADI, G., J. W. ANDERSON, Stanford University Press, Stanford, and J. W. BLAYLOCK. 1978. Uptake CA. of hydrocarbons from marine 16. KOZLOFF, E. N. 1974. Seashore life sediments contaminated with Prudhoe of Puget Sound, the Strait of Georgia, Bay crude oil: influence of feeding type and the San Juan Archipelago and of test species and availability of adjacent regions. University of polycyclic aromatic hydrocarbons. Washington Press, Seattle and Journal of the Fisheries Research London. Board of Canada. 35:608-614. 17. —. 1993. Seashore life of the northern 27. SCOTT, P. V., and J. A. BLAKE. 1998. Pacific coast: an illustrated guide to The Mollusca Part 1: the Aplacophora, northern California, Oregon, Polyplacophora, Scaphopoda, Bivalvia Washington, and British Columbia. and Cephalopoda. Taxonomic atlas of University of Washington Press, the benthic fauna of the Santa Maria Seattle. Basin and the Western Santa Barbara 18. LAMMENS, J. J. 1967. Growth and Channel. Vol. 8. Santa Barbara reproduction in a tidal flat population of Museum of Natural History, Santa Macoma balthica (L.). Netherlands Barbara, CA. Journal of Sea Research. 3:315-382. 28. WANG, J., H. LIN, X. HE, J. LIN, Y. 19. LEVINTON, J. S. 1991. Variable HUANG, R. LI, C. ZHENG, F. ZHENG, feeding behavior in three species of and J. JIANG. 2014. Biodiversity and Macoma (Bivalvia, Tellinacea) as a community structural characteristics of response to water flow and sediment macrobenthos in the Chukchi Sea. transport. Marine Biology. 110:375- Acta Oceanologica Sinica. 33:82-89. 383. 20. LUTTIKHUIZEN, P. C., J. DRENT, K. T. C. A. PEIJNENBURG, H. W. VAN DER VEER, and K. JOHANNESSON. 2012. Genetic architecture in a marine hybrid zone: comparing outlier detection and genomic clines analysis in the bivalve Macoma balthica. Molecular Ecology. 21:3048-3061. 21. MARRIAGE, L. D. 1954. The bay clams of Oregon. Contribution No. 20. Fish Commission of Oregon, s.l. 22. POWELL, C. L. 2001. Geologic and molluscan evidence for a previously misunderstood late Pleistocene, cool water, open coast terrace at Newport Bay, southern California. Veliger. 44:340-347. 23. QUAYLE, D. B. 1970. The intertidal bivalves of British Columbia. British Columbia Provincial Museum, Victoria, BC, Canada. 24. RAE, J. G. 1978. Reproduction in two sympatric species of Macoma (Bivalvia). Biological Bulletin. 155:207- 219. 25. —. 1979. Population dynamics of two sympatric species of Macoma A publication of the University of Oregon Libraries and the Oregon Institute of Marine Biology Individual species: http://hdl.handle.net/1794/12908 and full 3rd edition: http://hdl.handle.net/1794/18839 Email corrections to: [email protected]