i; 
TRANSACTIONS 
OF THE 
SAN DIEGO SOCIETY OF NATURAL HISTORY 
Volume XII, No. 19, pp. 319-332, fig. 1 
THE MARINE MOLLUSCAN FAUNA OF 
GUADALUPE ISLAND, MEXICO 
Volume XII, No. 20, pp. 333, 334, fig. 1 
A NEW MOLLUSK FROM SAN FELIPE, 
BAJA CALIFORNIA 
BY 
E. P. CHACE 
Curator of Conchology, San Diego Museum of Natural History 
SAN DIEGO, CALIFORNIA 
Printed for the Society 
October 16, 1958 
Fig. 1. Ocenebra seftoni sp. nov. Holotype (left) and paratype. 
Millimeter scale at right. 
THE MARINE MOLLUSCAN FAUNA OF 
GUADALUPE ISLAND, MEXICO 
BY 
E. P. Chace 
CONTENTS 
Introduction 321 
Faunal Relationships 322 
List of Mollusks and Brachiopods 323 
A New Species of Gastropod 331 
Literature Cited 332 
INTRODUCTION 
Guadalupe Island is 250 statute miles south-southwest of San Diego and 
162 miles off the coast of Baja California. The island is 22 miles long and 
4 to 6 miles wide. The highest point, 4257 feet above sea level, rises some 
16,000 feet above the floor of the ocean. Thus the island is surrounded by 
deep water. 
The part of the island above sea level is volcanic in origin. Strong (1954) 
suggested from the character of the lava and the amount of disintegration that 
its geologic age might be Pliocene. Johnson (1953) reported a small fossil 
marine fauna probably of Upper Tertiary or Quaternary age. In 1957 Dr. 
Carl L. Hubbs found exposures of Pleistocene fossils near the high-tide line 
at several points around the island, and in December of that year he and the 
writer collected about 50 pounds of shells and matrix at three localities. This 
material, representing a warm- water fauna, is under study. 
Strong and Hanna (1930) listed 87 species of marine mollusks from 
Guadalupe Island, collected mainly by an expedition of the California Academy 
of Sciences in 1925. Strong (1954) increased the number to 116 species on 
the basis of a collection of 82 species by M. Woodbridge Williams on an 
expedition of the Scripps Institution of Oceanography in 1946. Pilsbry (1927) 
treated the land and freshwater mollusks of the island. 
Since 1945 Dr. Hubbs and his associates from the Scripps Institution 
have collected mollusks on several trips to the island. Some of this material 
was collected in the littoral zone, some was dredged, and some was brought 
up by divers. Most of this material has come to the San Diego Museum of 
Natural History, and it has now been identified except for some microscopic 
shells. Since this material includes 77 species not reported from the island 
before, it seems worth while to publish a new list. 
322 San Diego Society of Natural History 
FAUNAL RELATIONSHIPS 
Since there are no protected bays on Guadalupe Island, the only littoral 
species are those of exposed habitats, such as Littorina, Acmaea, Lottia, and 
Haliotis. Most of the species listed are from deeper water. 
Many species are represented in the collections by only one or two speci- 
mens each. Several species were found only in one dredge haul, which happened 
to hit a mud pocket; these include Lima subauriculata, Leiomya scaber, Cuspi- 
daria pectinata, Thracia squamosa, and Crenella megas. And each big collection 
has added several species to the list. These facts suggest that sampling has 
been somewhat haphazard and that further collecting may add many species. 
Nevertheless, since eight collecting trips have yielded only 193 species of 
mollusks, the marine molluscan fauna of Guadalupe Island may be character- 
ized as scanty. 
Of the 193 species of marine mollusks known from Guadalupe Island, 
149 species, or 77.2 percent, belong to the Southern California Fauna, though 
some of these extend as far south as Cedros Island or beyond. Twenty-one of 
these, or 10.9 percent, are not otherwise known south of San Diego. Thirty- 
four species or 17.6 percent, belong to the Panamic Fauna, occurring on the 
mainland between San Diego and Panama but apparently not north of San 
Diego. Three of these are known only from Guadalupe Island and Panama: 
Bursa calcipicta Dall, Liotia heitni Strong 8C Hanna, and Crenella megas Dall. 
(Distributional data are mostly from Keen [1937].) 
As with the other terrestrial and marine biota of Guadalupe Island, the 
mollusks show some endemism. Ten species, or 5.2 percent of the marine 
molluscan fauna, are not known to occur elsewhere. These are: 
Ocenebra seftoni Chace Rissoina willetti Strong 
Diastema slevini Strong Rissoella bakeri Strong 
Alabina jordani Strong Astraea guadalupeana Berry 
Rissoina guadalupensis Strong Haliotis californiensis Swainson 
Rissoina lowei Strong Glycymeris guadalupensis Strong 
Only two species of brachiopods have been collected at Guadalupe Island. 
Both occur also in southern California. 
Scharff (1911) believed that Guadalupe Island and the other islands off 
the west coast of North America were remnants of a large land mass reaching 
in the distant past from Alaska to Peru and extending a considerable distance 
west of the present coastline. He claimed that the flora and fauna of the 
islands supported this hypothesis. It is now generally believed, however, that 
Guadalupe Island is an oceanic island and that its biota has resulted from 
fortuitous dispersal. Since many of the molluscs are kelp dwellers or are as- 
sociated with kelp, Strong and Hanna (1930) believed that much of the 
molluscan fauna had arrived on drifting kelp from the islands of southern 
California. 
Chace — Marine Mollusks of Guadalupe Island 323 
LIST OF MOLLUSKS AND BRACHIOPODS 
With one or two exceptions, the systematic arrangement of this list is 
that of Strong (1954). Trips on which the various species were collected are 
indicated as follows — S: California Academy of Sciences in 1925; W: M. 
Woodbridge Williams in 1946; 50, 54, 55, 56, and 57: Scripps Institution in 
1950, 1954, 1955, 1956, and 1957. Notes as to abundance are based only on 
the collections of 1950 to 1957. 
Gastropoda 
Umbraculidae 
Tylodina fungina Gabb (W, 57) . Two specimens in dredgings. 
Umbraculum ovale Carpenter (57) . Two specimens in dredgings. 
ACTEONIDAE 
Acteon punctocaelata (Carpenter) (54). Several specimens. 
ACTEOCINIDAE 
Acteocina angustior Baker 8C Hanna (S, W, 57). A few specimens. 
Acteocina magdalenensis Dall (50, 57). A few specimens each trip. 
Acteocina planata (Carpenter) (54). Nine specimens in dredgings. 
Retusa harpa (Dall) (S, 50). Seven specimens in dredgings. 
SCAPHANDRIDAE 
Cylichna attonsa Carpenter (50) . Eight specimens. 
Akeratidae 
Haminoea angelensis Baker & Hanna (54). One specimen. 
SlPHONARIIDAE 
Williamia peltoides (Carpenter) (S, W, 55). One specimen. 
Conidae 
Conus calif ornicus Hinds (50, 54, 57) . Apparently fairly common. 
TURRIDAE 
Kurtzia beta (Dall) (S). 
Mangelia barbarensis Oldroyd (54) . Fifteen specimens in dredgings. 
Mangelia interlirata Stearns (W). 
Mitromorpha crassaspera Grant & Gale (50). Three specimens. 
Mitromorpha filosa (Carpenter) (W, 50, 54). 
Philbertia crystallina (Gabb) (50) . 
324 San Diego Society of Natural History 
Marginellidae 
Cypreolina pyriformis (Carpenter) (S, W, 50, 54) . 
Cystiscus jewettii (Carpenter) (S, W, 57) . 
Cystiscus minor (C. B. Adams) (54). One specimen in dredgings. 
Cystiscus polttulus (Dall) (S, W, 54) . 
Hyalina calif ornica (Tomlin) (S, W, 50, 57) . 
MlTRIDAE 
Mitra catalinae Dall (S) . 
Mitra fultoni E. A. Smith (54) . One specimen in dredgings. 
Fasciolariidae 
Fusinus kobelti (Dall) (54, 57). One specimen each trip. 
Buccinidae 
Cantharus lugubris (C. B. Adams) (54). Two specimens. 
Nassariidae 
Nassarius insculptus (Carpenter) (W, 50, 54, 57). 
COLUMBELLIDAE 
Aesopus arestus Dall (S) . 
Aesopus eurytoides (Carpenter) (W, 50). Three specimens in dredgings. 
Aesopus sanctus Dall (W). 
Anachis subturrita Carpenter (S, W) . 
Mitrella carinata (Hinds) (50). Five specimens. 
Parametaria duponti (Kiener) (50) . One very small specimen. 
MURICIDAE 
Ceratostoma nuttallii (Conrad) (50, 57). Eight specimens in the two trips. 
Maxwellid gemma (Sowerby) (50, 57). One specimen each trip. 
Ocenebra gracdlima (Stearns) (W) . 
Ocenebra poulsoni (Carpenter) (W) . 
Ocenebra seftoni Chace (50, 57) . Five specimens. 
Thaisinae 
Acanthina lugubris (Sowerby) (W, 50, 54, 57) Common. 
Epitonhdae 
Epitonium sp. cf. E. apiculatum Dall (50). Three specimens. 
Epitonium bellastriatum (Carpenter) (54) . One specimen. 
Epitonium calif ornicum Dall (W) . 
Epitonium sp. cf. E. columbianum Dall (50). One specimen. 
Epitonium sawinae Dall (50) . Three specimens. 
Turbonilla (Pyrgiscus) halidoma Dall & Bartsch (50) . 
Chace — Marine Mollusks of Guadalupe Island 325 
Janthinidae 
Janthina globosa Blainville (50) . Two small ones. 
Eulimidae 
Eulima calif ornica (Bartsch) (50). Three specimens. 
Pyramellidae 
Odostomia (Miralda) aepynota Dall & Bartsch (W, S) . 
Odostomia (Menestho) amilda Dall & Bartsch (W) . 
Odostomia (Menestho) callipyrga Dall & Bartsch (55). One specimen. 
Odostomia (Chrysallida) clementina Dall & Bartsch (W) . 
Odostomia (Chrysallida) deceptrix Dall & Bartsch (S). 
Odostomia (Iolina) eucosmia Dall & Bartsch (S) . 
Odostomia (Ividella) navisa Dall & Bartsch (S, W). 
Odostomia (Chrysallida) pulcia Dall & Bartsch (W) . 
Odostomia (Ivara) turricula Dall SC Bartsch (S) . 
Odostomia (Chrysallida) virginalis Dall & Bartsch (S, W). 
Cypraeidae 
Cypraea spadicea Swainson (50) . One specimen. 
Erato columbella Menke (W, 50). Eight specimens. 
Trivia calif orniana (Gray) (54). Four specimens. 
Trivia solandri (Gray SC Sowerby) (W, 57) . One specimen. 
Ranellidae 
Bursa calcipicta Dall (W). Judging from photographs of the type specimen, 
this species is very close to the following species. 
Bursa calif ornica (Hinds) (S, 50, 54, 57) . Many specimens. 
Triphoridae 
Triphora sp. cf. T. chamberlini Baker (50) . One specimen. 
Triphora pedroana Bartsch (S, W) . 
Cerithiopsidae 
Cerithiopsis guadalupensis Strong (S) . 
Cerithiopsis oxys Bartsch (S, W) . , 
Metaxia diadema Bartsch (S, W) . 
Seila montereyensis Bartsch (S, W) . 
Cerithiidae 
Alabina diomede Bartsch (50). One specimen. 
Alabina jordani Strong (S, W) . 
Bittium interfossum (Carpenter) (S) . 
Diastoma slevini Strong (S, 50, 54, 57) . Common in dredgings. 
326 San Diego Society of Natural History 
Caecidae 
Caecum californicum Dall (S). 
Fartulum hemphdli Bartsch (S, W) . 
Vermetidae 
A letes squamigerus Carpenter (W). 
Bivonia compacta Carpenter (57) . Several on Haliotis shells. 
Spiroglyphus lituellus (Morch) (W, 50, 57). Six on Haliotis shells. 
Vermicularis eburnea (Reeve) (50) . A few small specimens. 
TURRITELLIDAE 
Turritella orthosymmetra Berry (50, 54). Several specimens, mostly small. 
LlTTORINIDAE 
Littorina planaxis Philippi (S, W, 50, 54, 57). Common. 
FOSSARIDAE 
Iselica jenestrata (Carpenter) (S). 
LlTIOPIDAE 
Alaba jeannettae Bartsch (S) . 
Barleeiidae 
Barleeia calif ornica Bartsch (S, W) . 
RlSSOIDAE 
Alvania aequisculpta Keep (S) . 
Alvania cosmia Bartsch (S, W) . 
Alvania oldroydae Bartsch (S, W). 
Alvania purpurea Dall (S, W, 50). A few specimens in dredgings. 
Amphithalamus inclusus Carpenter (S). 
Amphithalamus tenuis Bartsch (S). 
Nodulus kelseyi Bartsch (S) . 
Rissoinidae (as used by Dall) 
Rissoina calif ornica Bartsch (S, W) . 
Rissoina cleo Bartsch (S, W) . 
Rissoina guadalupensis Strong (S, W) . 
Rissoina lowei Strong (S, W, 57) . Several specimens. 
Rissoina willetti Strong (S, W) . 
RlSSOELLIDAE 
Rissoella bakeri Strong (S). 
Chace — Marine Mollusks of Guadalupe Island 327 
Hipponicidae 
Hipponix antiquatus (Linnaeus) (S, W, 50, 57). Two specimens. 
Hipponix tumens Carpenter (S, W, 50, 57) . Three specimens. 
Calyptraeidae 
Crepidula (Crepipatella) lingulata Gould (S, W, 50, 54, 57). Common on 
Astraea undosa Wood. 
Crepidula perforans Valenciennes (57) . One specimen. 
Vitrinellidae 
Macromphalina occidentalis Bartsch (50) . One specimen. 
Naticidae 
Lamellaria stearnsi orbiculata Dall (57). One specimen. 
Acmaeidae 
Acmaea digitalis Eschscholtz (S, W, 50, 54, 57). Several specimens. 
Acmaea limatula Carpenter (W, 50, 57). A few specimens. 
Acmaea mesoleuca var. vespertina Reeve (57). A few specimens. 
Acmaea paleacea Gould (S, W). 
Acmaea pelta Eschscholtz (S, W) . 
Acmaea scabra (Gould) (50). Several specimens. 
Lottia gigantea Gray (S, W, 50, 54, 57). Many specimens. 
Phasianellidae 
Tricolia pulloides (Carpenter) (S, W, 50) . 
Tricolia (Eulithidium) rubrilineata (Strong) (S, W). 
Turbinidae 
Astraea guadalupeana Berry (50). One specimen, with A. inequalis. 
Astraea inequalis (Martyn) [= A. gibberosa (Dillwyn)] (57). The two 
specimens are close to the original figure of Trochus inequalis (Martyn 
1784, pi. 31), and they match the original figures of A. diademata 
(Valenciennes 1846, pi. 3, figs. 2-2b). 
Astraea lithophora (Dall) (W). 
Astraea sp. cf. A. petrothauma Berry (50). One specimen. 
Astraea undosa (Wood) (S, 50, 54, 57) . Many specimens; apparently more 
variable than on the mainland. 
Homolopoma carpenteri (Pilsbry) (W, 57). A few specimens. 
Homolopoma paucicostatum (Dall) (S, W) . 
Homolopoma luridum (Dall) (55). Two specimens. 
328 San Diego Society of Natural History 
Liotiidae 
Liotia acuticostata Carpenter (S, W) . 
Liotia calif ornica Dall (S, 50) . Five specimens. 
Liotia fenestrata Carpenter (S) . 
Liotia beimi Strong & Hertlein (50, 57) . Several specimens. 
Trochidae 
Calliostoma splendens Carpenter (S, 50, 57) . Two specimens. 
Calliostoma sp. (W) . An unidentified species also in 1957. 
Margarites acuticostata Carpenter (W, 50, 54, 57) . Common in dredgings. 
Margarites parcipicta (Carpenter) (S, W) . 
Norrisia norrisii (Sowerby) (S, W, 50, 54, 57) . Many specimens. 
Tegula gallina (Forbes) (S, W). 
Tegula gallina multifilosa (Stearns) (50, 57). Several specimens. 
Tegula regina (Stearns) (S, 50, 54, 57). Several specimens. 
Vitrinellidae 
Circulus rossellinus Dall (S) . 
Teinostoma invallatum (Carpenter) (S, W) . 
Teinostoma supravallatum (Carpenter) (S, W) . 
Haliotidae 
Haliotis californiensis Swainson (S, 54, 57) . Many specimens. 
Haliotis corrugata Gray (S, 55) . Only four or five specimens. 
Haliotis cracherodii Leach (S, W) . 
Haliotis sp. cf. H. julgens Philippi (S, 54, 57). Not typical of H. julgens; 
may be a new species. 
FlSSURELLIDAE 
Fissurella volcano Reeve (W, 50, 54) . Only a few specimens. 
Megathura crenulata (Sowerby) (50, 54). Three specimens; evidently not 
common. 
Pelecypoda 
Arcidae 
Area bailyi (Bartsch) (S). 
Glycymeridae 
Glycymeris guadalupensis Strong (S, W, 50, 54, 57) . Common in dredgings. 
Chace — Marine Mollusks of Guadalupe Island 329 
Philobryidae 
Philobrya setosa (Carpenter) (S, W) . 
Mytilidae 
Crenella Columbiana Dall (57) . One specimen. 
Crenella divaricata (d'Orbigny) (S, W) . 
Crenella megas Dall (50) . Fifteen valves. 
Lit h o pha ga plumula (Hanley) (54). One specimen. 
Modiolus pallidulus Dall (50) . Two specimens. 
Pectinidae 
Hinnites gigantea (Gray) (W) . 
Pecten diegensis Dall (50, 54) . Several valves. 
Pecten lowei Hertlein (50) . One valve. 
Pecten pernomus Hertlein (50, 54, 57) . Many good pairs. 
Limidae 
Lima subauriculata (Montague) (50,54). Many valves. 
Thraciidae 
Thracia diegensis Dall (W) . 
Thracia squamosa Carpenter (50, 54, 57) . Many small valves. 
Lyonsiidae 
Lyonsia calif ornica nesiotes Dall (50, 54, 57) . Several live specimens. 
CUSPIDARIIDAE 
Cuspidaria pectinata (Carpenter) (50) . Two valves. 
Leiomya scaber (Carpenter) (50, 54) . Three pairs and several valves. 
ASTARTIDAE 
Bernardina baker i Dall (W) . 
Carditidae 
Glans carpenteri (Lamy) (W) . 
Milneria kelseyi Dall (S) . 
Milneria minima (Dall) (W) . 
Chamidae 
Chama buddiana C. B. Adams (50) . Two upper valves. 
Chama pellucida Browerip (S, W) . 
Thyasiridae 
Thyasira barbarensis (Dall) (54). One valve. 
330 San Diego Society of Natural History 
Ungulinidae 
Diplodonta subquadrata Carpenter (50). Eight valves. 
LUCINIDAE 
Lucina approximate! (Dall) (50,54). Six specimens plus some valves. 
Lucina calif ornica Conrad (S, W, 50, 54) . A few valves. 
Leptonidae 
Kellia laperousii Deshayes (W, 50) . One valve. 
Cardiidae 
Cardium biangulatum Broderip & Sowerby (54). Several pairs and valves. 
Protocardia centifilosa (Carpenter) (50). Two valves. 
Veneridae 
Antigona fordi Yates (W, 54). Several pairs and valves. 
Psephidea cymata Dall (S, W, 50, 54) . Several pairs and valves. 
Psephidea salmonea (Carpenter) (54). Three pairs and nine valves. 
Transenella puella (Carpenter) (S, W, 50, 54, 57) . Many live specimens and 
valves. 
Tellinidae 
Tellina pacijica Dall (W, 54, 57) . Two pairs. 
Semelidae 
Semele incongrua Carpenter (54). One specimen. 
CORBULIDAE 
Grippina calif ornica Dall (S) . 
SCAPHOPODA 
Dentalhdae 
Cadulus fusiformis Pilsbry & Sharp (S) . 
Dentalium berryi Smith & Gordon (50) . One specimen. 
Dentalium splendidulum Sowerby (50). One specimen in dredgings. 
Siphonodentalium quadrifissatum Pilsbry & Sharp (S, W, 50, 57). Many 
specimens. 
Polyplacophora 
Lepidopleuridae 
Lepidopleurus rugatus Pilsbry (57). One specimen. 
Lepidochitonidae 
Lepidochitona sp. (55). One very small specimen. 
Nuttallina calif ornica Reeve (57). Three specimens. 
Chace — Marine Mollusks of Guadalupe Island 331 
ischnochitonidae 
Ischnochiton biarcuatus Dall (57) . One specimen. 
Ischnochiton mertensi (Middendorff) (57). Two specimens. 
ACANTHOCHITONIDAE 
Acanthochitona arragonites Carpenter (55). Two specimens. 
Pteropoda 
Cavolinidae 
Carolina inflexa (Lesueur) (50) . Seven specimens. 
Carolina occidentalis Dall (50). One specimen. 
Clio pyramidata Rang (50). Four fragments. 
Curierina columella Rang (50) . One specimen. 
Brachiopoda 
Terebratu lidae 
Terebratulina unguicula Carpenter (50). One valve. 
Terebratellidae 
Platidia sp. cf. P. anomioides radiata Dall (57). Three specimens and five 
valves. 
A NEW SPECIES OF GASTROPOD 
Ocenebra seftoni sp. nov. 
Shell small, white with a light tan-colored band on the shoulder and 
another below the periphery and with a few darker spots on the spiral cords and 
between the axial ribs on the base. Nuclear whorls \y 2 , squarish, a prominent 
keel at the top of the first whorl and a second keel developing below it on the 
last half of the nuclear. Later whorls 5, slopingly shouldered and distinctly 
angled at the periphery. Two spiral cords on the first whorl, increasing to 4 
on the penultimate and to 9 on the body whorl. Axial ribs 9, rather strong, 
reaching from suture to suture and down over the base. Whole surface with 
fine axial lamellae, which are strongest where the cords pass over the axial 
ribs. Aperture oval, the outer lip thickened, especially where it joins the 
previous whorl; three denticles within. Callus rather heavy on the body whorl 
and on the slightly twisted columella. Siphonal canal about half as long as the 
aperture and well covered, the small umbilical chink nearly covered by the 
end of the columellar callus. Measurements of the holotype: height 12 mm.; 
diameter 6.2 mm.; height of the aperture 3.4 mm. Color description taken 
from one of the paratypes, which is brighter colored than the type. 
332 San Diego Society of Natural History 
The holotype is number 12955 in the conch ological collection of the San 
Diego Natural History Museum. It was dredged in about 40 fathoms by Dr. 
Carl L. Hubbs and party, February 2, 1950, at Melpomene Cove, Guadalupe 
Island, Baja California, Mexico. Paratypes are at the California Academy of 
Sciences and at the Museum of Comparative Zoology, Harvard University. 
The species is named for Mr. Joseph Sefton, then owner of the Research Ship 
Orca, from which the type was collected. 
The angular nuclear whorls indicate that the new species is closely re- 
lated to Ocenebra crispatissima Berry, from Catalina Island, and to members 
of the O. barbarensis group. It is especially similar to O. crispatissima but 
has fewer spiral chords on the body whorl and a shorter siphonal canal. 
LITERATURE CITED 
Johnson, Clifton W. 
1953 Notes on the geology of Guadalupe Island, Mexico. Am. Jour. 
Sci. 251: 231-236. 
Keen, A. Myra 
1937 An abridged check list and bibliography of west North American 
marine Mollusca. 1-88. Stanford University Press. 
Martyn, Thomas 
1784 The universal conchologist . . . vol. 1 [Numbering of plates 
varies.] 
PlLSBRY, H. A. 
1927 Expedition to Guadalupe Island, Mexico, in 1922. Land and 
freshwater mollusks. Proc. Calif. Acad. ser. 4. 16: 159-203, 
pis. 6-12. 
Scharff, Robert Francis 
1911 Distribution and origin of life in America, i-xvi, 1-497. Con- 
stable & Co., Ltd-, London. 
Strong, A. M. 
1954 The marine molluscan fauna of Guadalupe Island, Mexico. Min. 
Conch. Club So. Calif. 142: 6-10. 
Strong, A. M., and G. D Hanna 
1930 Marine Mollusca of Guadalupe Island, Mexico. Proc. Calif. 
Acad. ser. 4. 19: 1-6. 
Valenciennes, Achille 
1846 Voyage autour du monde sur ... la Venus, pendant . . . 1836- 
1839. Adas.