Vnl fi Nn ? Pages The TABULATA April 1, 1973

MINUTE SHELLS - Part 3 by Bert Draper

From the Pacific Coast of North abalones. There are no minute species America—from Alaska to the west coast in this family; however, two closely of Baja California— at least 600 spe- related families (ScissurelIidae and cies of small or minute shells (gener- FissurelIidae)do include such species. ally under ten millimeters in greatest In both of these families the shells dimension) have been described and have slit-bands as do the abalones,but named. Even more species are known there is only a single opening in the from the Panamic Province—from the slit-band instead of several as In the Gulf of California to Ecuador and Nor- abalones. On our coast, the family thern Peru, including the off-shore ScissurelIidae includes only minute or islands as far West as the Galapagos microscopic species. Genus Soissurella Islands. of this family has four species, in In my discussion of minute shell all of which the opening in the slit- species, it would be too great a task band consists of a slot extending in- to try to include all of these species, ward from the edge of the outer lip. so I will limit it to those species The largest species is S. kelseyi Dal I, more commonly encountered and to those 1905 which has been found from British rarer species which for some reason Columbia to the Coronado islands off are especially interesting. Certain the Northern Baja California coast. It genera include so many species that it reaches 5.5 mm in diameter. S. ohiri- will be wiser to discuss generic char- eova Dal I, 1919 from Chirikoff Island, acteristics and then pick some typical Alaska; S. epicharis McLean, 1970 from species to discuss as representatives the Galapagos Islands; and S. keenae of the genus or of its subgenera. The McLean, 1970 from the southern part of order in which I will cover these spe- the Gulf of California, are all deep cies will follow the same taxonomic water species. The latter two are pic- order as used by Dr. James McLean in tured in Myra Keen's book. In all of his book MARINE SHELLS OF SOUTHERN these,the slit-band extends around the CALIFORNIA. (I urge all readers in- periphery of the shell ending in a terested in minute species to obtain narrow slotted opening in the last a copy of this book, if you do not one-sixth of the final whorl. already have one.) It contains des- The genus Sinezona3 of the same criptive information on nearly one family, appears to have but one valid hundred species which are of such size species in the Eastern Pacific waters, as to fa I I in the small or minute cat- S. rimuloides (Carpenter, 1865). The egory, and has included good photo- microscopic shells of these tiny mol- graphs of each species. lusks have been found in finely sifted For minute shells of the Panamic grunge from eel grass roots or under Province, Dr. Myra Keen has provided kelp, almost anywhere from as far figures and some descriptions of quite north as San Francisco to as far south a few of these species in her Second as Chile and westward at least to the Edition of SEA SHELLS OF TROPICAL WEST Galapagos Islands. This species is AMERICA. I will include some of these well figured in both the McLean and and some species that she has only Keen books. Adult shells have a very mentioned by name, but time and space distinctive elongate oval opening or will not permit thorough coverage of fissure in the slit-band slightly back the Panamic minute shells, and I cer- from the edge of the outer lip. In tainly have not gone far enough with juvenile shells this opening may start these species to do so anyway. at the outer lip as a slit. Under a The first family in the Taxonomic microscope these little shells often order of Gastropods is Haliotidae, the show slanted axial ribs below the slit-

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April 1, 1973 The TABULATA Page 9 band and spiral lines on the base. The of these that look much alike from the largest of these shelIs seldom reach outside, but differ inside the shell, I mm and to the naked eye they look in that P. sooperi has a small arching like small white grains of sand. shelf just inside from the fissure The family Fissure 11idae also shows while P. galeata has this shelf plus a its relationship to the aba I ones by curving supporting sulcus between the having an opening or fissure in the shelf and the inner edge of the fiss- shell, but in some species the slit- ure. Figures 1 and 2 may help to show band is almost gone. . Several species this difference. The third species, of this family are small enough to P. punotoaostata Berry, 1947 (Fig. 3) fall into my minute shell category. is generally found only from deeper The first two, both deep water spe- water. It has minute punctations cies from our tropical waters, are along the inner edges of its ribs. Emarginula velasaoensis Shasky, 1961 Otherwise its shape and appearance is and Nesta galapagensis McLean, 1970. much like the other two species. One Both are described and figured in Myra other minute species of this family Keen's book. Three species of the ge- is found in the Gulf of California, nus Punaturella are quite small and Rimula mexioana Berry, 1969. Keen cov- may show up in dredged material or ers this species Well. Rimula astviota even beach wash along much of our McLean,1970 has recently been describ- shoreline. P. galeata (Gould, 1846) ed from the Gulf of California [=i?. and P. aooperi Carpenter, 1864 are two mexioana according to Keen - Ed.] and

(Fig. 1) Punaturella aooperi Carpen- (Fig. 2) Puncturella galeata Gould, ter, 1864- Internal view, showing 1846. Internal view, showing shelf shelf beneath apex, without support- and supporting sulcus. Shell length sulcus. Shell length 5.5 mm. 8 mm.

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(Fig. 3) Punaturella punotooastata (Fig. 4) Rimula mexicana Berry,1969. Berry, 1947. Dredged off Redondo Escondido Bay, Baja Cal. H. DuShane, Beach,Cal. by John Q. and Tom Burch, 1970. She 1.1 length 4.7 mm. 1935. She I I length 5 mm.

(Fig. 5) Five very small species of California ACMAEI DAE. L.to r. Aamaea rosacea Carpenter, 1864; Notoaamea pal- saaea (Gould. 1853),: N°toacmea depiata (Hinds, 1842); Aamaea triangularis (Carpenter, 1864)- and Collisella asmi Middendorff. 1847; AI I from San'Pedro, Calif, area. Col lection of B.C. Draper.

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Rimula aaliforniana Berry, 1964 from Catalina Island to Outer Baja Califor- nia. My photograph of R. mexioanaiFig. 4 ) is quite typical of the genus. The next family with some minute or quite small species is Acmaeidae,which has at least nine such species between Alaska and outer Baja California, and three from the Panamic Province. Two species from Alaskan waters,Aamaea ap- ioina Dal I, 1879 and A. rosea Da I I, 1872 have not been seen by the writer.. A.apicina is described as looking like a small A. mitra Rathke, 1833 with blunt rounded apex and a yellow or dull orange spot at the apex. A. rosea is of deep rose color on the outside, white with a rosy border on the inside It is smooth except for a few faint ridges from the apex,which is near the anterior margin. Genus Aamaea has two other minute species found along our coast on rocks or on stems of certain sea plants. A. rosacea Carpenter, 1864 is shown in Dr. McLean's book in one color form while my photograph (Fig.5) shows another color pattern. The basic color is pink or orange-brown, with (Fig. 6) Patellpidea semirubida white rays or dots extending out from (Dal I, 1914). Top and side views. the apex. Most shells found will be Puertecitos, Baja Calif. Length 6 mm under 5 mm'in length,but a large shell may reach 8 mm. A. triangularis (Car- penter, 1864) is a white shell with There are several small species of deep brown spots, one at the apex and genus Collisella: C. alveus (Conrad, five or six radiating out from the 1831, an Arctic species which is apex. A side view of the shell shows found as far south as British Colum- its triangular shape which gives it bia, occasionally reaching to 11 mm its name. Usually these shells are size, has dark brown rays in various under 6 mm, but one has been found patterns (Fig. 7). This species was that is nearly 9 mm in length. also names Aamaea paralella Da II, 1914 but alveus takes priority and it truly belongs in genus Collisella. C. asmi Genus Patelloidea has one small (Mi ddendorff, 1847) is a smaI I black species, semirubida (Dal 1,1914), which species which is usually found only on may be found throughout the Gulf of black tegulas [Tegula funebralis (A. California (Fig. 6). At first glance Adams, 1855) ] which they match in some of these shells look much like A. color and outer shell surface. Most of rosacea3 on closer study, however, the these shells are under 10 mm, but a red or brown markings take on a chev- few reach 11 or 12 mm. The interior is ron or triangular shape, and a side bluish and highly polished. Collisella view of the shell shows the basal mar- mitella (Menke, 1847) and C.strongiana gins curved away from the apex at ei- (Hertlei n, 1958) are two small Gulf ther end of the shell, and the apex species included in Myra Keen's book. rises much higher. In size this spe- cies occasionally reaches 7 mm in len- The genus Notoacmaea has four gth and over half that much in height. small species along our U.S. Pacific

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ta and the shell slopes quite concave- ly from the apex to the forward mar- gin. The color is gray with tan stri- pes radiating from the apex. It was described from a pleistocene fossil, but the writer has recent specimens ! from the San Pedro area. Juvenile specimens of many of the larger species of Acmaeidae are com- monly found in the type of grunge that yields the best minute shells. These small shells will often fool even ex- perienced col lectors, as they may look quite different from the adult shells of the same species, and they quite often have an adult appearance. Com- paring these shells with a growth ser- ies of the various species of Acmaeids will help clear up the proper identity of these she I Is. In Part 4 of this series, the next few families in the taxonomic order will be d i scussed.

(All photos by Bert Draper)

(Fig. 7) Collisella alvem (Conrad, 1831). Three specimens from Grant Island, Alaska, ex WiIlett Collec- tion. Largest 11 mm. INJURED ABALONE One of the unfortunate things about diving for abalone is that the animal Coast. N. depiota (Hinds, 1892) scme- may sustain deep punctures in its foot times grows somewhat above 10 mm out or other soft parts when it is scraped most shells will be found smaller. N. off a rock to be measured to ensure paleaoea (Gould, 1853)is much narrower that it has reached a legal harvest- and relatively higher in shape. Both able size. Many divers believe that of these species are found on eel abalone are hemophiliacs and that a grasses along the Southern California wounded one will bleed to death even coast, and south along Outer Baja Cal- if immediately placed back on the site ifornia. N. paleaoea also ranges north from which it was taken. to Canada.N. gabatella (Berry,l960) is a more ova I-shaped small species with The blood of abalones, like that of light brown narrow stripes radiating all mo Musks, lacks coagulating pro- out from the apex, which is set well tei ns and, consequently, these animals to the front of the shell and lower are susceptible to blood loss follow- than the midpoint. It has been ta- ing injury. This is prevented to some ken between San Pedro and San Diego. degree by the clumping together of N. lepisma (Berry, 1940) is our final blood cells; however, there is still a small limpet. This species looks much risk that fatalities will result from like N. depiota but is somewhat broad- even a minor injury. (Sea Secrets,Vol er and relatively lower. The apex is 16, No.5. International Oceanographic set even farther forward than indepio- Foundation.)

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