A Quarterly published by CALIFORNIA MALACOZOOLOGICAL SOCIETY, INC. Berkeley, California R. Stohler (1901-2000), Founding Editor Volume 48 ISSN 0042-3211 June 30, 2006 CONTENTS Effects of a Hen’s Egg Yolk Diet on Certain Inorganic Elements in the Snail Helisoma trivolvis (Colorado Strain) Joyce H. L. ONG, MICHAEL CHEJLAVA, BERNARD FRIED, AND JOSEPH SHERMA.......... Habitat Usage by the Page Springsnail, Pyrgulopsis morrisoni (Gastropoda: Hydrobiidae), from Central Arizona MICHABIIASIMIARTINEZ AND) DARRINUMO THOME 08 0... eck ele es ee lee eee ee A Light and Electron Microscopic Study of Pigmented Corpuscles in the Midgut Gland and Feces of Pomacea canaliculata (Caenogastropoda: Ampullariidae) EDUARDO KOCK, ISRAEL A. VEGA, EDUARDO A. ALBRECHT, HUGO H. ORTEGA, ANDY MUERED Ol CACHE O2VIAZOURZS May mneinv act sn oe Mines lal galt tie aie gaits eins a ses Diversity and Abundance of Tropical American Scallops (Bivalvia: Pectinidae) from Opposite Sides of the Central American Isthmus J. TRAVIS SMITH, JEREMY B. C. JACKSON, AND HELENA FORTUNATO .........00000000: Additions and Refinements to Aptian to Santonian (Cretaceous) Turritella (Mollusca: Gas- tropoda) from the Pacific Slope of North America UORIARID) IL, SOUURIES ANID) ILOUWIBUIA RO GMOs 6 oc dood ao bbeu des Sob bio ame cane bones The Veliger (ISSN 0042-3211) is published quarterly in January, April, July, and October by the California Malacozoological Society, Inc., % Santa Barbara Museum of Natural History, 2559 Puesta del Sol Road, Santa Barbara, CA 93105. Periodicals postage paid at Berkeley, CA and additional mailing offices. POSTMASTER: Send address changes to The Veliger, Santa Barbara Museum of Natural History, 2559 Puesta del Sol Road, Santa Barbara, CA 93105. Number 1 THE VELIGER Scope of the journal The Veliger is an international, peer-reviewed scientific quarterly published by the California Malaco- zoological Society, a non-profit educational organization. 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Send all business correspondence, including subscription orders, membership applications, payments, and changes of address, to: The Veliger, Dr. Henry Chaney, Secretary, Santa Barbara Museum of Natural His- tory, 2559 Puesta del Sol Road, Santa Barbara, CA 93105, USA. Send manuscripts, proofs, books for review, and correspondence regarding editorial matters to: Geerat Vermeij, Department of Geology, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA. This paper meets the requirements of ANSI/NISO Z39.48-1992 (Permanence of Paper). EMIT Hee JUL 1 8 20106 THE VELIGER es © CMS, Inc., 2006 The Veliger 48(1):1—7 (June 30, 2006) Effects of a Hen’s Egg Yolk Diet on Certain Inorganic Elements in the Snail Helisoma trivolvis (Colorado Strain) JOYCE H. L. ONG, MICHAEL CHEJLAVA Department of Chemistry, Lafayette College, Easton, Pennsylvania 18042, USA BERNARD FRIED* Department of Biology, Lafayette College, Easton, Pennsylvania 18042, USA AND JOSEPH SHERMA Department of Chemistry, Lafayette College, Easton, Pennsylvania 18042, USA Abstract. Graphite furnace atomic absorption spectrometry, flame atomic absorption spectrometry, and ion chro- matography were used to investigate several elements in the whole body, digestive gland-gonad complex (DGG), shell, and plasma of the pulmonate snail, Helisoma trivolvis (Colorado strain), maintained in artificial spring water (ASW) on two different diets, hen’s egg yolk (Y) and Romaine leaf lettuce (L). Whole body and DGG samples were analyzed for the following seven elements: sodium, potassium, calcium, magnesium, zinc, iron, and manganese. Of these, iron was present in a significantly higher concentration (Student’s t-test, P < 0.05) in the whole bodies of snails on the L-diet compared to those on the Y-diet. For the DGG analysis, calcium and potassium were present at significantly higher concentrations, and magnesium at a significantly lower concentration, in snails on the L-diet. Plasma was analyzed for calcium and iron, and no significant differences were found in the concentrations of these elements in snails on both diets. The shells of H. trivolvis, analyzed only for calcium, showed no statistical difference in the concentration of this element between snails on the L-diet versus those on the Y-diet. The Romaine leaf lettuce, the hen’s egg yolk, and the ASW were analyzed for certain elements: food samples for potassium, magnesium, calcium and iron, and ASW for calcium and iron. There were significantly higher concentrations of calcium and iron in the hen’s egg yolk compared to the Romaine leaf lettuce (Student’s t-test, P < 0.05). The ASW contained calcium at a concentration of 20.0 + 0.0 mg L™', and a trace amount of iron at 0.0307 + 0.017 mg L™!. The occurrence of certain elements in the snail may be considered as the ultimate result of passage of these elements from the lettuce or egg yolk upon which the snails were fed or the water in which they were maintained. INTRODUCTION has been used extensively in neurobiology studies (see Kater, 1974). Two of us (BF and JS) used a high fat diet (hen’s egg yolk) in the late 1980s to induce hyperlipidemia and hy- perlipemia in the medically important planorbid snail Biomphalaria glabrata (Say, 1816) (see reviews in Fried & Sherma, 1990, 1993). In addition to studies on neutral and polar lipids in the snails maintained on the high fat diets, recent work examined carbohydrates (Kim et al., Helisoma trivolvis (Say, 1816) is a ubiquitous fresh water planorbid snail in North America. Numerous strains of this snail have been reported, but the taxonomic relation- ships within the species are still uncertain. One of us (BF) has maintained two strains of H. trivolvis in the labora- tory for a number of years. One strain, H. trivolvis (Penn- sylvania strain), is heavily pigmented with melanin and has a black body. This strain serves as a vector of the 37-collar-spined echinostome, Echinostoma_ trivolvis 2001) and lipophilic pigments (Kim et al., 2002; Evans (Cort, 1914), in the USA (see Huffman & Fried, 1990 for et al., 2004) in such snails. Recently, our laboratory has a review). The second strain, H. trivolvis (Colorado examined the lipid composition of H. trivolvis (Co) in strain), is refractory to infection with E. trivolvis, lacks snails maintained on a hen’s egg yolk diet. As expected, melanin, and has an orange-red body. The Colorado strain both juvenile and adult snails maintained on this diet ac- cumulated significant amounts of certain lipids compared * Author to whom correspondence should be addressed. Tele- to cohorts maintained on a lettuce leaf diet (Schneck et phone: (610)330-5463; fax: (610)330-5705, e-mail: friedb@ al., 2003a, b). lafayette.edu. There are no studies on elements in snails raised on Page 2 various diets, and the present study was designed to de- termine the effects of a high fat diet (hen’s egg yolk) on the element composition of H. trivolvis (Co) snails. Ele- ments in the snails raised on the high fat diet were com- pared with those of snails maintained on a low fat diet (Romaine lettuce leaf). Previous studies have examined certain elements in snails independent of diet or infection with larval trematodes. Some of these representative stud- ies and their findings are the following: Layman et al. (1996a) used atomic absorption spectrometry (AAS) and inductively coupled plasma-atomic emission spectrome- try (ICP-AES) to study metal ions in the DGGs of H. trivolvis (PA) infected with E. trivolvis and uninfected H. trivolvis snails. They found sodium present in signifi- cantly higher amounts, and magnesium and manganese in significantly lower amounts, in the infected versus unin- fected DGGs. Layman et al. (1996b) measured metallic ions in B. glabrata snails infected with E. caproni and in uninfected snails by ICP-AES and found no significant differences (Student’s ¢-test, P > 0.05) in the concentra- tions of the metals in whole infected versus whole unin- fected snails. Kaufer et al. (2002) analyzed the effects of Euhaplorchis californiensis Martin, 1950 infection on the metal ion concentrations in the DGGs of the marine snail Cerithidea californica Haldeman, 1840 by graphite fur- nace atomic absorption spectrometry (GFAAS) and ion chromatography (IC) and reported calcium present in sig- nificantly higher amounts, and magnesium in significantly lower amounts, in infected versus uninfected DGGs. Ong et al. (2004) investigated the effects of Schistosoma man- soni Sambon, 1907 infection on inorganic elements in the whole bodies of B. glabrata snails and reported signifi- cantly higher amounts of calcium, cadmium, manganese, and sodium in the whole infected versus whole uninfected snails. Because there are no previous studies on the effects of a high fat diet on the element content of planorbid snails, the purpose of this study was to examine certain elements in A. trivolvis (Co) maintained on a hen’s egg yolk diet. Controls consisted of cohort snails maintained on a diet of Romaine leaf lettuce. MATERIALS AND METHODS Snail Maintenance Stock cultures of H. trivolvis (Co) were maintained from eggs to sexually mature adults at 23 + 1°C in aer- ated glass jars, each containing 10 to 20 snails in 800 mL of artificial spring water (ASW) (Schneck et al., 2003a). The ASW was prepared as described by Ulmer (1970). One culture of 25 snails with shell lengths ranging from 16-20 mm was maintained ad libitum on boiled Romaine lettuce leaf (L-diet) for 20 weeks. Another culture of 25 snails (16-20 mm shell length) was first maintained on the L-diet for 16 weeks and then on the boiled hen’s egg The Veliger, Vol. 48, No. 1 yolk diet (Y-diet) for an additional four weeks. For all the cultures, food and water were changed twice a week. Sample Preparation All glassware used for sample preparation and element analysis was cleaned as follows: first washed with soap and rinsed with tap water, soaked in 10% nitric acid so- lution for at least 2 hr, rinsed with deionized water at least three times, and finally dried in an oven overnight at 250°C. These steps were performed to ensure removal of any elements adhering to glass surfaces. Trace metal grade nitric acid (Fisher Scientific, Fair Lawn, New Jer- sey) was used in all experiments throughout this research. Whole Body, Digestive Gland-Gonad Complex (DGG), and Shell The whole bodies, DGGs, and shells of 10 individual snails (n = 10) on each diet (lettuce or yolk) were pre- pared as described below. During sample preparation, all snail dissections were performed in 6 cm diameter petri dishes. The shells of the snails were gently cracked with a blunt forceps, and the snail bodies removed from the shells and weighed (range 50 to 250 mg blotted wet weight). Shell samples were collected at the same time whole body samples were prepared and were obtained as follows: the shell pieces remaining in the petri dish after removal of the snail bodies as described above were col- lected with a forceps and weighed (range 30 to 120 mg blotted wet weight). For DGG samples, snail bodies were first obtained as described above. Each DGG was then dissected free of the visceral mass under a dissecting mi- croscope with forceps and weighed (range 51 to 100 mg blotted wet weight). The visceral masses were discarded. All samples were rinsed several times with deionized wa- ter, and kept moist in 6 cm diameter petri dishes lined with filter paper that had been previously dampened with deionized water. Prior to analysis, each sample (whole body, DGG, or shell) was digested in 2 mL of boiling concentrated nitric acid in a 10 mL beaker. Each digested sample was diluted to 10.00 mL in a volumetric flask with 2% (v/v) nitric acid. Whole body and DGG samples were analyzed for the following elements: calcium, iron, potassium, magne- sium, sodium, manganese, and zinc. Calcium, potassium, magnesium, and sodium were determined by FAAS, and iron, manganese, and zinc by GFAAS. Shell samples were analyzed for calcium by FAAS. To ensure that sam- ple concentrations were within the range of the calibra- tion curve of the standards, the shell samples were diluted 2000-fold with 2% (v/v) nitric acid. For all calcium anal- yses, a lanthanum (III) nitrate solution [31 g lanthanum (III) nitrate hexahydrate salt diluted in 100 mL 2% (v/v) nitric acid] was added in an amount that was equivalent to 10% of the flask size to remove interfering phosphate ions that prevent the volatilization of calcium. For sodium J. H. L. Ong et al., 2005 Page 3 analysis, potassium chloride [4 g potassium chloride di- luted in 100 mL 2% (v/v) nitric acid] was added in a volume that was 10% of the flask size to suppress ioni- zation of sodium atoms. Plasma An additional 20 snails were used to prepare the plas- ma samples (10 snails each on the L- and Y-diets). Sam- ples of plasma, which is defined as hemolymph minus the hemocyte fraction, were obtained as follows: to obtain hemolymph, snail shells were cracked open gently with a blunt forceps and the hemolymph allowed to ooze out into a dry petri dish. The hemolymph was removed from the petri dish using a Pasteur pipet and pooled in Eppen- dorf tubes. Hemolymph from three or four snails on the lettuce diet was pooled to prepare a sample of approxi- mately 300 pL. Likewise, hemolymph was pooled from three or four snails on the yolk diet to prepare an ap- proximate 250 pL sample from that population. For each diet, three pools of the hemolymph (n = 3) were prepared from 10 snails. The hemolymph samples were centrifuged at 5600 x g for 5 min to obtain a pellet (consisting of hemocytes and some residual snail debris) that was discarded, and the supernatant (plasma) was used. The plasma was trans- ferred to a new Eppendorf tube using a Pasteur pipet. The sample was then diluted 10-fold in 0.01 M nitric acid and analyzed for calcium by IC and for iron by GFAAS. Snail Food Romaine lettuce and hen’s eggs (domestic chickens) were boiled for approximately 10 min prior to use. Only the green, leafy portion of the lettuce and the yolk of the egg were used for analyses. Both foods were blotted dry prior to weighing. Approximately 5 g of lettuce and 1 g of yolk were weighed accurately in separate beakers, and three samples were prepared for each diet (n = 3). The lettuce sample was digested in 37 mL of boiling concen- trated nitric acid in a 25 mL beaker until a thin yellow film remained at the bottom of the beaker. The yolk was digested in 32 mL of boiling concentrated nitric acid in a 25 mL beaker. Concentrated sulfuric acid (5 mL) was added to the digest to aid in raising the temperature of the solution. A dark colored film remained at the end of the yolk digestion. For both diets, the resulting film was dissolved in 10 mL in a volumetric flask with 2% (v/v) nitric acid. The lettuce and yolk were analyzed for cal- cium, iron, potassium, and magnesium by FAAS, and for iron by GFAAS. Artificial Spring Water (ASW) ' Three samples of ASW (n = 3) were collected and analyzed for calcium and iron by FAAS and GFAAS, respectively. The ASW samples were diluted 100-fold for calcium determination and 2-fold for iron determination using 2% (v/v) nitric acid. Elemental Analysis by Atomic Absorption Spectrometry (AAS) and Ion Chromatography (IC) GFAAS was utilized to quantify the levels of iron, manganese, and zinc, while FAAS was used to analyze for calcium, potassium, magnesium, and sodium. Calcium determination in the plasma samples was performed by IC because sample volumes were too small to allow the use of FAAS. The GFAAS instrument was a GBC 932 plus (GBC Scientific Equipment, Arlington Heights, Hlinois) atomic absorption spectrometer with GBC GF3000 graphite fur- nace system, separate hollow cathode lamps (Varian, Inc., Walnut Creek, California) for each element determined, GBC PAL3000 autosampler, and GBC Advanta version 1.33 software. The instrument had a double beam design and a deuterium background correction system. All stan- dard and sample volumes were 20 pL. Stock standard solutions of each metallic 1on in 2% HNO, were made and autodiluted with 2% HNO, into multiple working standards by the instrument. The lamp current and wave- length, slit width, and oven temperature program were optimized for each element. All samples were analyzed in triplicate to obtain mean absorbance values. The in- strument provided the experimental concentration of each test solution by interpolation from the calibration curve (mean absorbance versus the working range of the ele- ment: 100-2000 pg L~! for Fe and Zn, 25-300 pg L™! for Mn). The FAAS instrument was a Varian SpectrAA-20 atomic absorption spectrometer (Varian, Inc.) with a 1- lamp turret arrangement, separate hollow cathode lamps (Varian Techtron) for each element determined, and an air-acetylene burner. The instrument had a double-beam design and no background-correction system. Wavelength settings, slit selection, lamp current, and gas flows were optimized for each element. Five standard solutions were prepared for analysis of each element with the following working ranges (mg L~'): Ca 0.20—5.0, Mg 1.0—-50, Na 0.040—2.0, K 1.0—50. The standards and samples were analyzed using three 30 s integrations. The instrument provided the experimental concentration of each test so- lution by interpolation from the calibration curve (mean absorbance versus element concentration). The IC instrument was a DX-120 ion chromatograph (Dionex, Sunnyvale, California) with an AS40 automated sampler, IonPac CG12A guard column (4 X 50 mm), IonPac CS12A cation exchange analytical column func- tionalized with weak phosphonic and carboxylic acid groups (4 X 250 mm), and self-regenerating membrane cation suppressor system. The isocratic mobile phase was 20 mM methanesulfonic acid at a flow rate of 0.98 mL/ The Veliger, Vol. 48, No. 1 Table 1 Mean concentration + standard deviation in mg g'! of wet tissue of whole bodies obtained by FAAS and GFAAS for elements in H. trivolvis maintained on the L- and Y-diets. Table 2 Mean concentration + standard deviation in mg g'! of wet tissue of the DGGs obtained by FAAS and GFAAS for elements in H. trivolvis snails maintained on the L- Element L-diet* Y-diet® Value of P Ca bys ae De 4.26 + 1.8 0.292 Fe 0.0187 + 0.0060 0.0112 + 0.0036 0.00409" K 1.34 + 0.34 1.27 + 0.20 0.628 Mg 0.863 + 0.25 0.863 + 0.22 0.998 Mn 0.00632 + 0.0018 0.00470 + 0.0032 0.195 Na 0.273 + 0.054 0.324 + 0.15 0.331 Zn 0.0647 + 0.061 0.0446 + 0.024 0.348 and Y-diets. Element L-diet® Y-diet® Value of P Ca 2.44 + 0.57 1.68 + 0.41 0.00329> Fe 0.0406 + 0.019 0.0234 + 0.019 0.0602 K 0.927 + 0.32 0.669 + 0.18 0.0414» Mg 0.498 + 0.096 0.648 + 0.14 0.0119° Mn 0.00185 + 0.00059 0.00178 + 0.00056 0.792 Na 0.425 + 0.14 0.343 + 0.078 0.122 Zn 0.0254 + 0.015 0.0431 + 0.029 0.0829 “n = 10 samples, where each sample consisted of the whole body of an individual snail. > Differences significant at P < 0.05 as determined by the Stu- dent’s f-test. min. Three standard calcium solutions with concentra- tions of 5, 50, and 100 mg L™! were prepared in 0.01 M nitric acid for generation of a linear least-squares calibra- tion curve. The calibration curves and interpolated sam- ple concentrations were obtained using PeakNet Chro- matography Workstation software. The injection volumes of standards and samples were 25 wL, and all solutions were analyzed in triplicate. Data Analysis For all the three analytical methods (GFAAS, FAAS, and IC), the measured element concentration in the test sample solutions was provided by the instrument by in- terpolation of bracketed samples from the calibration curve. For the whole body, DGG, shell, and diet samples, the concentration of each element (mg g~!) in the samples was calculated using the following equation: , : (C)(V)(D) concentration of element = —————— (1) (M)( 1000) where C is the test solution concentration from the in- strument (mg L™!), V is the volume of the initial dilution of the sample following digestion (10 mL), D is the ap- propriate dilution factor made for each analysis, and M is the mass of the wet sample (g). The mean concentra- tions of the elements in the samples obtained from the lettuce fed snails versus the yolk fed snails were statis- tically compared with the Student’s f-test (two-sample as- suming unequal variances) in Microsoft Excel 2000. For the plasma and ASW samples, the concentration of the elements (mg L~!) determined were calculated with the following equation: Concentration of element = (C)(D) (2) where C is the test solution concentration provided by the instrument (mg L~'), and D is the dilution factor (plasma “n = 10 samples, where each sample consisted of the DGG of an individual snail. > Differences significant at P < 0.05 as determined by the Stu- dent’s f-test. 10; ASW iron 2, calcium 100). Again, Microsoft Excel 2000 was used to compare for statistical differences in the mean concentrations of the elements in the plasma samples of the snails on the two different diets using the Student’s t-test (P < 0.05). RESULTS The seven elements determined in the whole bodies of snails maintained on both diets were present in the fol- lowing concentration order: calcium > potassium > mag- nesium > sodium > zinc > iron > manganese. The con- centrations of these elements were elevated in snails on the L-diet, with the exception of magnesium, which was present in equal concentrations for snails on both diets, and sodium, which was at a higher concentration in snails on the Y-diet. Iron was the only element with a signifi- cantly higher concentration in the whole bodies of snails on the L-diet compared to the snails on the Y-diet (Stu- dent’s r-test, P < 0.05). Table 1 lists quantitative data for the snail mass-adjusted concentrations of the elements, calculated using Equation 1, for the whole bodies of H. trivolvis (Co) on both diets. The same seven elements were quantified in the DGGs. Table 2 lists quantitative data for the snail mass-adjusted (calculated using Equa- tion |) element concentrations in the DGGs of H. trivolvis (Co) snails on both the L- and Y-diets. For DGGs of snails on the Y-diet, the elements were present in a con- centration order similar to the one in the whole bodies of the snails described above. The DGGs of the snails main- tained on the L-diet showed the following order in con- centration of the elements: calcium > potassium > mag- nesium > sodium > iron > zinc > manganese. These elements were all present at higher concentrations in DGGs of snails on the lettuce diet with the exception of magnesium and zinc, which were at lower concentrations compared to DGGs of snails on the Y-diet. There was a Jere Ongret aly2005 Table 3 Mean concentration + standard deviation in mg g! ob- tained by FAAS and GFAAS for the wet weights of Ro- maine leaf lettuce and hen’s egg yolk. Element Lettuce* Egg yolk* Value of P Ca 0.989 + 0.23 1.85 + 0.27 0.0138° Fe 0.00468 + 0.0012 0.0148 + 0.0026 0.00839» K 1.78 + 0.64 1.27 + 0.063 0.303 Mg 0.252 + 0.073 0.287 + 0.024 0.509 4n = 3 samples, where the lettuce samples were approximately 5 g each, and the egg yolk samples were approximately 1 g each. > Differences significant at P < 0.05 as determined by the Stu- dent’s f-test. significantly lower concentration of calcium and potassi- um, and a significantly higher concentration of magne- sium, in the DGGs of snails maintained on the egg yolk diet than those maintained on the lettuce diet (Student’s t-test, P < 0.05). The concentrations of calcium (calculated using Equa- tion 1) in the shells of H. trivolvis (Co) on the L- and Y- diets were 389 + 54 mg g™! and 378 + 62 mg g"|, re- spectively, and were not significantly different (Student’s t-test, P > 0.05). The plasma samples, analyzed only for calcium and iron, gave the following results (calculated using Equation 2): 278 + 43 mg L“! and 233 + 9.7 mg L! in snails on the L- and Y-diet, respectively, for the calcium analysis; 10.3 + 1.2 mg L"! and 10.1 + 1.6 mg L™! in snails on the L- and Y-diet, respectively, for the iron analysis. No significant differences were found be- tween the concentrations of both elements in the plasma of snails maintained on both the L- and Y-diet (Student’s t-test, P > 0.05). The results obtained for certain elements in Romaine lettuce leaf and hen’s egg yolk are summarized in Table 3. These foods were analyzed for the elements calcium, iron, potassium, and magnesium. Among these four ele- ments determined, the calcium and iron concentrations in the hen’s egg yolk were significantly higher than those found in the lettuce (Student’s t-test, P < 0.05). The results for the calcium and iron determination in the ASW (calculated using Equation 2) were 20.0 + 0.0 mg L“! and 0.0307 + 0.017 mg L~! for calcium and iron, respectively. According to the standard water hardness classification of the United States Geological Survey, this calcium concentration indicates that the ASW is of a slightly hard level. DISCUSSION The elements that were analyzed in this investigation were selected for several reasons. First, potassium, mag- nesium, sodium, and calcium are among the elements known to be of highest concentrations in many biological Page 5 systems (Prosser, 1973). These elements have diverse functions in animal cells and are necessary for normal cellular functions. For instance, calcium, potassium, and magnesium are important for muscle contraction and nerve cell function. The construction of skeletal and shell components is dependent on calcium and magnesium. Magnesium is also an essential cofactor for some en- zymes, including the ATPases and kinases (Prosser, 1973). Iron, present in the heme portion of the oxygen carrier hemoglobin, was selected based on visual obser- vations during laboratory work that the colors of the he- molymph of the snails maintained on the lettuce versus yolk diets were different. Snails fed the lettuce diet had hemolymph that was bright red while snails fed the yolk diet had hemolymph that was yellow-orange. The heavy metals zinc and manganese are necessary in trace amounts in biological systems, but are toxic in high con- centrations (Prosser, 1973). Zinc and manganese both act as cofactors of certain enzymes found in living systems. The results obtained are similar to those of Kalyani (2001), who examined certain elements in the giant Af- rican land snail, Achatina fulica Bowdich, 1822, and es- timated calcium to be the major element in both the soft body and shell, followed by potassium, magnesium, and sodium. We found the same order in the concentrations of these elements in the whole bodies and DGGs of H. trivolvis (Co) on the L- and Y-diets. The whole body analysis of H. trivolvis (Co) included the major regions of the snail, i.e., the head-foot, viscera, and DGG. The significant depletion of iron in the snail whole bodies on the Y-diet, compared to snails on the L- diet, possibly reflects the presence of blood sinuses in the viscera and head-foot regions of yolk-fed snails, which contain low iron content in the hemolymph and tissue. The snail DGG (particularly the digestive gland por- tion) is the main site of interest in dietary studies because it is a good indicator of snail metabolic activity. The DGG contains the digestive gland or hepato-pancreas (liver) and the reproductive glands of the snail, the ovo- testis. A major function of DGG cells is the storage of various metals held in membrane-insoluble granules in the cells (Howard et al., 1981; Simkiss, 1981; Dallinger & Wieser, 1984; Bebianno & Langston, 1995). Further- more, the DGG is an important target site for most met- abolic and enzymatic activities (Dallinger & Wieser, 1984; Bebianno & Langston, 1995). In our study, calcium and potassium were significantly higher, and magnesium significantly lower, in the DGGs of snails on the L-diet compared to the Y-diet. The DGGs of the yolk-fed snails were yellow-white, in contrast to the DGGs of the lettuce- fed snails, which were dark green-brown. Schneck et al. (2003a) and Evans et al. (2004) made similar observa- tions on the gross appearance of DGGs from snails on the two diets. This color difference may reflect an in- creased deposition of fat in the DGGs of the yolk-fed Page 6 snails, and a subsequent alteration in the element concen- trations. Red blood, due to hemoglobin dissolved in the plasma, is characteristic of planorbid snails. We analyzed iron in the plasma to see if there were differences in the concen- tration of this element in the snails on the two diets. Schneck et al. (2003a) reported that snails on the L-diet yielded more hemolymph compared to the Y-diet (100 wL and 50 pL per snail, respectively). Furthermore, snails fed the L-diet had a red hemolymph compared to the yellow-orange color in snails on the Y-diet. These obser- vations suggested that the hemoglobin content, and per- haps the iron content, was different in both snail popu- lations. However, the iron concentration was not signifi- cantly lower in the yolk-fed snails as compared to the lettuce-fed snails (Student’s r-test, P > 0.05). The color difference in the plasma of the snails probably reflects the presence of lipophilic pigments, i.e., carotenes and xan- thophylls, in the plasma of snails maintained on the yolk diet. } The shells of H. trivolvis (Co) were analyzed only for calcium, the chief constituent of shells. The calcium con- centrations in the shells of snails fed the L- and Y-diets were determined to be 389 + 54 mg g™! and 378 + 62 mg g_!, respectively. According to Marxen et al. (2003), the constituents of the molluscan shell are calcium car- bonate, present in a concentration of 95 to 99.9%, and organic material, 0.1 to 5%. Calcium carbonate is the in- soluble product of the two major inorganic ions in pul- monate shells, calcium and bicarbonate; both ions are ob- tained from the animal’s nutrients and the environment, with bicarbonate being additionally drawn from the ani- mal’s metabolic production of carbon dioxide (Luchtel et al., 1997). Calcium carbonate is usually present in one of two predominate crystalline lattice configurations in the pulmonate shell, aragonite or calcite, and sometimes va- terite (Luchtel et al., 1997). Assuming that all of the cal- cium present in the shell is in the form of calcium car- bonate, the percentage of calcium carbonate in the H. trivolvis shell obtained in this study is equivalent to 94% and 97% in the lettuce- and yolk-fed snails, respectively. Schneck et al. (2003a) observed that the shells of H. trivolvis (Co) snails maintained on the Y-diet were more fragile and, therefore, more susceptible to cracking than those on the L-diet, suggesting that snails on the Y-diet were lacking calcium in their shells. We found no signif- icant difference in calcium concentration in shells from snails on both diets; hence, shell fragility must be due to factors other than the calcium content of the shell. Romanoff & Romanoff (1949) reported that the most abundant element in egg yolk is phosphorus, accounting for 0.588% of the yolk’s mass. Other inorganic elementals found in egg yolk in small quantities, and their percent- ages, included calcium (0.144%), magnesium (0.128%), chlorine (0.123%), potassium (0.112%), and sodium (0.070%). Iron and sulfur were present in trace amounts The Veliger, Vol. 48, No. 1 of 0.011% and 0.016% in yolk, respectively. We found that the order of the elements in our egg yolk samples was calcium > potassium > magnesium > iron. The magnesium level in hen’s egg yolk in our study was lower than that reported by Romanoff & Romanoff (1949), and this may be attributed to a difference in the method of analysis (method not reported by Romanoff & Romanoff, 1949). Additionally, Romanoff & Romanoff (1949) stressed the important fact that the concentrations of el- ements in egg yolk, albumen, and shells are dependent upon the concentrations of elements in the diets fed to the hens. We found no literature on inorganic elements present in Romaine lettuce. Our findings on the elements in Ro- maine lettuce appear to be the first ever reported. The ASW of Ulmer (1970) is widely used by malacologists and parasitologists to maintain planorbid snails. Our quantitative results on calcium and iron concentrations in this water may be of interest to these workers. The oc- currence of certain elements in the snail tissue, plasma and shell may be considered as the ultimate result of pas- sage of these elements from the lettuce or hen’s egg yolk upon which the snails were fed, or the water in which they were maintained. LITERATURE CHE D BEBIANNO, M. & W. J. LANGSTON. 1995. Induction of metallo- thionein synthesis in the gill and kidney of Littorina littorea exposed to cadmium. Journal of the Marine Biological As- sociation of the United Kingdom 75:173-186. DALLINGER, R. & W. WIEsER. 1984. Patterns of accumulation, distribution and liberation of Zn, Cu, Cd, and Pb in different organs of the land snail Helix pomatia L. Comparative Bio- chemistry and Physiology B 79:117—124. Evans, R. T.,, B. Friep & J. SHERMA. 2004. Effects of diet and larval trematode parasitism on lutein and B-carotene con- centrations in planorbid snails as determined by quantitative high performance reversed phase thin layer chromatography. Comparative Biochemistry and Physiology B 137:179—-186. FrieD, B. & J. SHERMA. 1990. Thin layer chromatography of lipids found in snails. Journal of Planar Chromatography- Modern TLC 3:290—299. Friep, B. & J. SHERMA. 1993. Effects of a high fat diet on the lipid composition of Biomphalaria glabrata (Planorbidae: Gastropoda). Trends in Comparative Biochemistry and Physiology 1:941—958. Howarb, B., P. C. H. MitcHeLt, A. RitcHie, K. SIMKIss & M. TAYLOR. 1981. The composition of intracellular granules from the metal-accumulating cells of the common garden snail (Helix aspersa). Biochemistry Journal 194:507—511. HUFFMAN, J. E. & B. FrieD. 1990. Echinostoma and echinosto- miasis. Advances in Parasitology 29:215—269. KALYANI, R. 2001. Nutritional studies on soft body and shell of Achatina fulica (Pulmonata: Stylommatophora). American Malacological Bulletin 16:195—200. Kater, S. B. 1974. Feeding in Helisoma trivolvis: the morpho- logical and physiological bases of a fixed action pattern. American Zoologist 14: 1017-1036. KAUFER, S. W., M. CHEJLAVA, B. FRIED & J. SHERMA. 2002. Ef- fects of Euhaplorchis californiensis (Yrematoda) infection J. H. L. Ong et al., 2005 Page 7 on metallic ions in the host snail Cerithidea californica (Gastropoda). Parasitology Research 88:1080—1082. Kim, Y., B. FRIED & J. SHERMA. 2001. Thin layer chromatograph- ic analysis of carbohydrates in Biomphalaria glabrata snails maintained on a high fat diet. Journal of Planar Chromatog- raphy-Modern TLC 14:61—63. Kim, Y., B. FRIED & J. SHERMA. 2002. Thin layer chromatograph- ic analysis of lutein and B-carotene in Biomphalaria glabra- ta maintained on a high fat diet. The Veliger 45:256—258. LayMAN, L. R., A. C. Dory, K. M. KOEHNLEIN, B. FRIED & J. SHERMA. 1996a. Effects of Echinostoma trivolvis (Tremato- da) infection on metallic ions in the host snail Helisoma trivolvis (Gastropoda). Parasitology Research 82:19—21. LAYMAN, L. R., A. C. Dory, K. M. KOEHNLEIN, B. FRIED & J. SHERMA. 1996b. Measurement of metallic ions in Biom- phalaria glabrata (Gastropoda) infected with Echinostoma caproni (Trematoda) and in uninfected snails. Journal of the Helminthological Society Washington 63:256—258. LucuTeL, D. L., A. W. MARTIN, D.-O. I. INGRITH & H. H. Borer. 1997. Mollusca II. In E W. Harrison & A. J. Kohn (eds.), Microscopic Anatomy of Invertebrates. Vol. 6B, Mollusca II. John Wiley & Sons, Inc.: New York, NY. 481 pp. MARXEN, J. C., W. BECKER, D. FINKE, B. HASSE & M. EPPLE. 2003. Early mineralization in Biomphalaria glabrata: mi- croscopic and structural results. Journal of Molluscan Stud- ies 69:113-121. Onc, J. H. L., M. CHEJLAVA, B. FRIED, K. M. KOEHNLEIN, G. L. BOSAVAGE & J. SHERMA. 2004. Effects of Schistosoma man- soni infection on inorganic elements in the snail Biomphal- aria glabrata. Journal of Helminthology 78:343—346. Prosser, C. L. 1973. Inorganic ions. Pp. 79-81, 100—102 in C. L. Prosser (ed.), Comparative Animal Physiology. 3rd ed. W. B. Saunders Co.: Philadelphia, PA. Romanorfr, A. L. & A. J. ROMANOFF. 1949. Chemical composi- tion. Pp. 355, 359 in The Avian Egg. John Wiley & Sons, Inc.: New York, NY. SCHNECK, J. L., B. FRIED & J. SHERMA. 2003a. Thin layer chro- matographic analysis of neutral lipids and phospholipids in Helisoma trivolvis (Colorado Strain) maintained on a high fat diet. The Veliger 46:325—328. SCHNECK, J. L., B. FRIED & J. SHERMA. 2003b. High-performance thin layer chromatographic analysis of lipids in juvenile Hel- isoma trivolvis (Colorado Strain) maintained on a hen’s egg yolk diet. Journal of Planar Chromatography-Modern TLC 16:405—407. SIMkIss, K. 1981. Cellular discrimination processes in metal ac- cumulating cells. Journal of Experimental Biology 94:317— 327. Umer, M. J. 1970. Notes on rearing snails in the laboratory. Pp. 143-144 in A. J. MacInnis & M. Voge (eds.), Experiments and Techniques in Parasitology. W. H. Freeman: San Fran- cisco, CA. The Veliger 48(1):8-16 (June 30, 2006) EV BEIGE © CMS, Inc., 2006 Habitat Usage by the Page Springsnail, Pyrgulopsis morrisoni (Gastropoda: Hydrobiidae), from Central Arizona MICHAEL A. MARTINEZ* U.S. Fish and Wildlife Service, 2321 W. Royal Palm Rd., Suite 103, Phoenix, Arizona 85021, USA (*Correspondent: mike-martinez @fws.gov) DARRIN M. THOME U.S. Fish and Wildlife Service, 2800 Cottage Way, Rm. W-2605, Sacramento, California 95825, USA Abstract. We measured habitat variables and the occurrence and density of the Page springsnail, Pyrgulopsis mor- risoni (Hershler & Landye, 1988), in the Oak Creek Springs Complex of central Arizona during the spring and summer of 2001. Occurrence and high density of P. morrisoni were associated with gravel and pebble substrates, and absence and low density with silt and sand. Occurrence and high density were also associated with lower levels of dissolved oxygen and low conductivity. Occurrence was further associated with shallower water depths. Water velocity may play an important role in maintaining springsnail habitat by influencing substrate composition and other physico-chemical variables. Our study constitutes the first empirical effort to define P. morrisoni habitat and should be useful in assessing the relative suitability of spring environments for the species. The best approach to manage springsnail habitat is to maintain springs in their natural state. INTRODUCTION The role that physico-chemical habitat variables play in determining the occurrence and density of aquatic micro- invertebrates in spring ecosystems has been poorly stud- ied. This field deserves more attention because microfau- na play critical roles in energy flow and nutrient cycling in the spring environment, and the sustainability of eco- systems depends upon their persistence (New, 1998). Lo- cally endemic invertebrates such as springsnails (Hydro- biidae), riffle beetles (Elmidae), and amphipods (Amphi- poda) can be excellent environmental indicators of aquat- ic conditions because their presence or absence is often associated with particular chemical and physical condi- tions (Greeson, 1982; Hershler, 1998). Numerous invertebrate species are imperiled, particu- larly those inhabiting aquatic environments. As of No- vember 1, 2004, there were 32 species of snails (aquatic and terrestrial), 70 species of clams, and 21 species of crustaceans listed as threatened or endangered under the Endangered Species Act within the United States (U.S. Fish and Wildlife Service, 2004a). Despite the recognized status of such species, the availability of empirical infor- mation on the ecology and biology of these organisms to assist resource managers in developing and implementing effective conservation and recovery programs is limited. The Page springsnail, Pyrgulopsis morrisoni (Hershler & Landye, 1988), is medium-sized relative to other con- geners, 1.8 to 2.9 mm in shell height, endemic to the Upper Verde River drainage of central Arizona (Williams et al., 1985; Hershler & Landye, 1988; Hershler, 1994), with all known populations existing within a complex of springs located along Oak Creek near the town of Page Springs, Yavapai County. The species is a candidate for listing as threatened or endangered under the Endangered Species Act (U.S. Fish and Wildlife Service, 2004b). What little is known about the ecology and biology of this species has been obtained through agency status re- views, anecdotal observations, and inferences drawn from literature on other springsnail congeners. Hydrobiids are strictly aquatic, relying on an internal gill for respiration. Their primary food source is periph- yton, and they generally graze on exposed surfaces (Tay- lor, 1987; Mladenka & Minshall, 2001). Pyrgulopsis snails are known to be oviparous. Raisanen (1991) sur- mised that P. morrisoni lay eggs during an annual period of reproduction in the winter. Mladenka & Minshall (2001) found that the Bruneau hot springsnail, P. bru- neauensis (Hershler, 1990), exhibited recruitment year- round. Among most prosobranchs, the veliger stage is completed in the egg capsule, and upon hatching, indi- viduals emerge into their adult habitat (Brusca and Brus- ca, 1990). No information is available on death and birth M. A. Martinez & D. M. Thome, 2005 Page 9 rates. Significant migration is undocumented although other small aquatic snails have been known to disperse by becoming attached to the feathers or the mud on the feet and legs of waterfowl and shorebirds (Dundee et al., 1967). Predators may include waterfowl, shorebirds, am- phibians, fishes, crayfish, leeches, and aquatic insects. No specific information on disease or parasites is available, but other aquatic snails have been known to serve as the intermediate hosts for trematodes. Springsnails occur in springs, seeps, marshes, spring pools, outflows, and diverse lotic waters, though the most common habitat for Pyrgulopsis is a rheocrene, or a spring emerging from the ground as a free-flowing stream (Hershler and Landye, 1988; Hershler, 1998). Springs- nails seem to prefer firm substrates such as cobble, rocks, woody debris, and aquatic vegetation, and are rarely found on or in soft sediment (Hershler, 1998; Raisanen, 1991; O’Brien and Blinn, 1999). Distribution of Pyrgu- lopsis within springs has been hypothesized as a function of stable temperature, water chemistry, and flow regime characteristic of the particular aquatic environment within which they occur (Hershler, 1984 and 1998). For exam- ple, O’Brien and Blinn (1999) found that dissolved free carbon dioxide plays a significant role in the distribution of the Montezuma Well springsnail, P. montezumensis (Hersler and Landye, 1988), and Mladenka and Minshall (2001) found water temperatures influence density and growth rate of P. bruneauensis. Although the current literature provides general insight into ecological conditions suitable for hydrobiids, spe- cies-specific information is needed due to the potential for significant inter-specific variation in physiological re- quirements. Accordingly, the objective of our study was to evaluate associations between habitat variables and oc- currence and density of P. morrisoni to provide a basic understanding of the species’ habitat usage. STUDY AREA The Oak Creek Springs Complex includes a number of spring heads located along Oak Creek (Landye, 1973, 1981; Williams et al., 1985; Arizona Game and Fish De- partment, 1988; Hershler and Landye, 1988). We gained access to Page/Cave Spring, Bubbling Spring, Bass Spring, and an unnamed spring (Figure 1). These aquatic environments are essentially isolated, mid-elevational, permanently saturated, spring-fed aquatic communities commonly described as ciénegas (Hendrickson and Minckley, 1985). Elevation in the Page Springs area is approximately 1070 meters. Riparian vegetation associated with Oak Creek and the springs complex includes velvet ash, Frax- inus velutina,; Fremont cottonwood, Populus fremontii; Arizona sycamore, Plantanus wrightii,; willows, Salix sp.; and mesquite, Prosopsis sp. Aquatic vegetation associat- ed with fine grained sediments, includes macrophytes such as watercress, Nasturtium officinale; duckweed, Lemna minor; water parsnip, Berula erecta; water pen- nywort, Hydrocotyl verticillata; water speedwell, Veron- ica anagalli aquatica; dock, Rumex verticillatus; water- weed, Elodea occidentalis; and pondweed, Potamogeton gramineus; and algae such as Rhizoclonium hieroglyphi- cum and Oscillatoria rubesens. METHODS We measured density of P. morrisoni in the Oak Creek Springs Complex over four sampling periods during the summer of 2001. Initially, 35 modified Hester-Dendy ar- tificial substrate samplers were placed randomly within the aquatic environment of accessible spring heads, spring runs, spring ponds, and spring pond outflows to quantify springsnail density. Artificial substrate samplers collect springsnails at densities comparable to those found in nearby natural substrata (O’Brien and Blinn, 1999). Samplers were constructed of round plates of masonite fastened together with an eye bolt. Each was composed of four round plates 75.49 mm in diameter and six round spacers 24 mm in diameter, all 1 cm thick, resulting in an effective sampling area of 330.86 cm? (Figure 2). Sam- pling periods were as follows: March 23 to May 10, May 10 to June 21, June 21 to August 2, and August 2 to September 25. At the end of each sampling period, we used a Hydro- lab Surveyor II to measure water temperature (°C), pH, dissolved oxygen (mg/L), and conductivity (wS/cm @ 25°C) adjacent to the sampler. We measured water depth with a meter stick or ruler (cm). We placed benthic fauna from each sampler into Whirl-Paks with 70% isopropyl alcohol or 95% ethyl alcohol, and transported them to the lab. We used a Stereozoom 7 Microscope to identify and count springsnails. After data collection, we returned each sampler to the aquatic environment. Over the course of the four sam- pling periods, several samplers were unrecoverable. As a result, the initial 35 samplers provided 94 independent samples for each variable. We classified substrate into one of four categories based on the predominant (>50%) composition surround- ing the sampler. Substrate categories were modeled after a modified Wentworth classification system for particle size (Cummins, 1962; McMahon et al., 1996). Initially, we established three substrate categories with the follow- ing particle size range (mm): silt and sand (<2); gravel and pebble (2 to 64); and cobble (64 to 256). Later, we observed that in certain areas dominated by silt and sand, the leaf structure of water pennywort often provided a surface area atypical of other aquatic macrophytes. Ac- cordingly, we split the silt and sand category into two sub-categories to capture potential differences provided by water pennywort. Those sub-categories are presented as silt and sand, and silt and sand with water pennywort. Page 10 The Veliger, Vol. 48, No. 1 Bubbling Spring © PAGE SPRINGS Bass Spring unnamed spring ® Cave Spring @ §=Springs @ Towns N —— Oak Creek ; 1 Miles A Roads Figure 1. Page springsnail study area, Yavapai County, Arizona. M. A. Martinez & D. M. Thome, 2005 Page 11 ZZ — a Figure 2. Modified Hester-Dendy artificial substrate sampler. We did not encounter snails in the cobble category, large- ly because we did not collect a sufficient number of sam- ples within cobbly areas (n = 6). Thus, for tests compar- ing snail density and presence between different substrate categories, we did not include the cobble classification. Prior to statistical analyses, we used Pearson’s corre- lation coefficients to evaluate the independence of pH, water temperature, dissolved oxygen, depth, and conduc- tivity. Temperature and pH were correlated with dissolved oxygen (7 > 0.60), and thus eliminated from further anal- yses. We kept dissolved oxygen instead of the former two variables because dissolved oxygen can be an important limiting factor for aquatic invertebrate respiration (Pen- nak, 1989). Moreover, although temperature differences as small as 4°C increased the production of viable fresh- water snail eggs in other studies (Dillon, 2000), we do not suspect that temperature was a significant factor in our study since 96% of our temperature data varied less than 4°C. Dissolved oxygen and conductivity were not highly correlated with one another (r = 0.331) and were both used as independent variables. Depth showed a fairly high correlation (r = 0.564) with conductivity, but the rela- tionship between the two variables is unclear because our range of depth measurements did not appear broad enough to influence water quality through thermal strat- ification. Thus, depth was assessed along with the other independent variables. We pooled data between sampling periods, as a modified-Levene equal variance test showed the variances in snail density between periods to be equal (F = 0.188, df = 3, 90, P = 0.904) and there were no differences in snail densities between periods (F = 0.13, df = 3, 90, P = 0.942). We pursued generalized tests, seeking differences in springsnail habitat between locations where springsnails were present and absent. We tested the following null hypotheses with respect to springsnail presence/absence: There is no difference according to substrate category, depth, dissolved oxygen levels, and conductivity levels. We used a 3 X 2 contingency table to test whether snail presence was independent of substrate category, and Mann-Whitney U-tests to assess differences in habitat variables between occupied and unoccupied locations. While our first hypotheses strove to characterize springsnail habitat in general, we also sought to charac- terize habitat quality by comparing snail densities among substrate categories, and between different levels of the continuous independent variables. We created low, me- dium, and high categories for each of the independent variables (dissolved oxygen, conductivity, and depth) us- ing the lower, middle, and upper 33rd percentiles of data within the independent variables. Using these categories, we tested additional null hypotheses with respect to springsnail density: There is no difference according to substrate category, depth, dissolved oxygen, or conduc- tivity. We used the Kruskal-Wallis one-way ANOVA on ranks to test the above hypotheses, and the Kruskal-Wal- lis multiple comparison z-value test for post-hoc compar- isons (Hintze, 2000). NCSS (Hintze, 2000) was used for all statistical tests. We used nonparametric tests since the data generally lacked normality, and transformations were unsuccessful. For all tests, significance was considered P = 0.05 and results are presented in the form (x + SE). RESULTS For all 94 samples, springsnail density averaged 0.069 + 0.0137 per cm’, ranging from 0.0 to 0.680 per cm?. We found springsnails in 48 samples, and where springsnails were found, their density averaged 0.135 + 0.023 per cm’. Throughout the study area (for locations with and without springsnails), dissolved oxygen levels averaged 8.694 + 0.273 mg/L, ranging from 5.78 to 18.5 mg/L; conductivity levels averaged 431 + 8.192 S/cm, ranging from 128 to 524 pS/cm; and water depth averaged 28.225 + 4.304 cm, ranging from 0.33 to 91.5 cm. Defining Habitat Using Presence/Absence Our contingency table analysis demonstrated that the occurrence of springsnails was not independent of sub- strate type (Table 1; x? = 10.531, df = 2, P = 0.005). The gravel/pebble category contained springsnails more often than expected, and both of the silt/sand categories contained springsnails less often than expected. Locations where springsnails were present were characterized by Pasest2 The Veliger, Vol. 48, No. 1 Table | 3 X 2 contingency table showing frequencies of Page springsnail presence and absence on three substrate cat- egories during sampling in the Oak Creek Springs Com- plex in Arizona, 2001. Expected frequencies in parentheses. Substrate Absent Present Total Gravel/pebble 14 (21.4) 33 (25.6) 47 Silt/sand 17 (11.4) 8 (13.6) D5 Silt/sand/water pennywort 9 (7.3) 7 (8.7) 16 Total 40 48 88 significantly lower dissolved oxygen levels (Figure 3A; Z = —5.268, P < 0.0001), lower conductivity levels (Figure 3B; Z = —4.732, P < 0.0001), and shallower depth (Fig- ure 3C; t = 2.135, df = 41, P = 0.039). Defining Habitat Quality Using Springsnail Density Springsnail density differed between the three habitat substrates from which we sampled (Figure 4; x? = 17.99, df = 2, P = 0.0003). Springsnail density in gravel/pebble was significantly greater than in the silt/sand substrates (both with and without water pennywort). Springsnail density was lower for the highest level of dissolved ox- ygen (0.005 + 0.005) compared to the lower two levels (Figure 5A; low = 0.084 + 0.021; med = 0.069 + 0.024; x? = 26.49, df = 2, P < 0.0001), lower for the highest two levels of conductivity than for the lowest level (Fig- ure 5B; low = 0.124 + 0.029; med = 0.020 + 0.010; high = 0.013 + 0.008; x? = 30.32, df = 2, P < 0.0001), and remained unchanged for all levels of water depth (Figure 5C; shallow = 0.074 + 0.003; med = 0.083 + 0.037; deep = 0.036 + 0.019; xy? = 2.83, df = 2, P = 0.242). DISCUSSION We found that substrate particle size was an important factor determining occurrence and density. P. morrisoni occurred more often and in greater densities in gravel and pebble substrates. They may prefer larger substrate be- cause it provides a reliable surface for the deposition of egg masses, facilitates mobility, and provides a suitable medium for production of periphyton, the snails’ pre- ferred food source. This, in turn, may result in higher recruitment and snail densities. Mladenka (1992) demonstrated that P. bruneauensis preferred gravel to sand because snails used hard surfaces to deposit their eggs. Pyrgulopsis females deposit single, small egg capsules on hard surfaces (Hershler, 1998). Larger substrates should be more conducive to oviposi- S) 12.0 7 = x =9,92 A SPN IEO SE =0.419 f= 5p Ss 10.0 1 4 @ z 9.0 ¥ z= X =7.32* Ae A n=A4l n=46 7.0 = Present Absent 600 4 X = 468 aaa = 5 SE =6.173 eI | X = 388* B YL 500 SE = 13.187 nN = 400 4 1p | = 300 3 200 5 = © 100 5 Y n=39 n=45 0 Present Absent 60.0 | x =37.91 50 0 4 SE = 6.78 C E 40.0 7 ¥ =20.23* aA SE = 5.00 teh i ra 30.0 (0) A 20.07 10.0 4 n=23 n=20 0.0 7 Present Absent Figure 3. Mean values for three habitat parameters where Page springsnail was present and absent in the Oak Creek Springs Complex in Arizona, 2001. Differences were tested with Mann- Whitney U-tests comparing sites with and without springsnails. *P < 0.05. tion because the surface provides improved stability over smaller, uncoalesced particles such as silt and sand. More- over, prosobranch snails have a distinct foot with a creep- ing planar sole and locomotion is facilitated by secretion of a mucous trail over which the animal glides (Brusca and Brusca, 1990). This type of locomotion likely re- quires less effort over large and stable surfaces. Smaller particles are also more likely to be displaced by water current, possibly burying snails and eggs. We did not include cobble within our analysis because our sample size in that category was small. However, we Page 13 M. A. Martinez & D. M. Thome, 2005 0.2 9 mm eS x =0.122B 5 ) SE = 0.024 D | Ss p> 4 < o 0.17 a X¥ =0.036 A 3 | SE = 0.016 a 2 | X =0.006 A = | SE = 0.003 N 0.07 _ : : Silt/ Gravel/ Silt/ Sand Pebble Sand/ n=25 n=A47 Water pennywort n= 16 Figure 4. Values for Page springsnail density (x + SE) in three different substrate types in the Oak Creek Springs Complex in Arizona, 2001. Means with the same letter did not differ when tested with a Kruskal-Wallis one-way ANOVA on ranks at a = 0.05. do not dismiss cobble as a potentially preferred substrate medium due to its large, stable character. P. morrisoni did not show a significant preference for water pennywort as a substrate medium. We found this surprising since anecdotal field observations convinced us that the species was abundant on the leaves of water pennywort. Upon reflection, perhaps our sampling technique did not capture the importance of water pennywort as a substrate medi- um. Water pennywort occurred within only one spring that we sampled. That spring, Bubbling Spring, is not a rheo- crene, but instead exists as a pond with a maximum mea- sured depth of 91.5 cm. Within Bubbling Spring pond, water pennywort occurred near spring vents and grew to a height of about 15-20 cm within the water column. Because samplers were placed in sediments near the stem base, the snail population present on the leaves may not have been able to access them. Perhaps this could be addressed by using the surface area of the macrophyte itself to quantify snail density as done by O’Brien and Blinn (1999). Nevertheless, we believe the potential suitability of wa- ter pennywort as a substrate medium for P. morrisoni deserves further investigation. A substrate-stratified field sampling technique or laboratory experiment may be use- ful to assess the importance of all substrate types. We found that mean dissolved oxygen concentrations differed by more than 2 mg/L in sites where springsnails were present versus sites where springsnails were absent. Moreover, regions with high dissolved oxygen concentra- tions had significantly lower snail densities than sites with low and medium concentrations. We do not suspect that depressed dissolved oxygen levels limited respiration be- cause we never encountered oxygen-poor conditions (minimum value = 5.78 mg/L). For common species of the pulmonate genus Physella, 2 mg/L is about the lim- iting level for dissolved oxygen to meet respiratory needs (Pennak, 1989). However, we have no reason to postulate that higher levels of dissolved oxygen would directly lim- it P. morrisoni occurrence and density, given that higher levels should more readily meet respiratory requirements. Thus, the negative relationship between dissolved oxygen and snail occurrence and density may be a function of “E 0.20 A 0.20 B 0.20, a 1S) i) S& 0.15 { 0.15 4 + 0.15 4 ia B 0.10 4 0.10 4 a 0.10 eal & 0.05 0.05 | 0.05 4 op 4 AS as & 0.00 + : = 0.00 0.00 + 7 r Low Med High Low Med High Shallow Med Deep n=29 n=29 n= 29 p= n=29 n=28 n=15 n=14 n=14 Dissolved Oxygen (mg/L) Low = 5.78—7.12 Med = 7.25-8.69 High = 8.70-18.5 Conductivity (uS/cm) Low = 128— 368 Med = 389-477 High = 478-524 Depth (cm) Shall = 0.33-7.50 Med = 7.80-30.48 Deep = 33.0—91.5 Figure 5. Values for Page springsnail density (< + SE) in relation to three different environmental variables in the Oak Springs Complex in Arizona, 2001. Values with same number did not differ when tested with a Kruskal-Wallis one-way ANOVA on ranks at a = 0.05. Low, medium, and high categories were created using the lower, medium, and upper 33rd percentiles of data within the independent variables. Page 14 other environmental variables that interact with both dis- solved oxygen and the snail. These may include the in- fluence of other gases and/or primary productivity. For instance, it is generally true that dissolved oxygen and carbon dioxide concentrations exhibit an inverse re- lationship within aquatic environments. Coupled with sunlight, carbon dioxide is the primary element driving photosynthesis. It is possible that regions within the Oak Creek Springs Complex characterized by low dissolved oxygen levels were also characterized by elevated levels of carbon dioxide and primary production, particularly at the periphytic level. Perhaps the relationship between dis- solved oxygen and occurrence and density of P. morri- soni is tied to the availability of periphyton. Whatever the mechanism, the proximity of spring vents may play an important role. Hershler (1984, 1998) noted that hydrobiid densities seem to decrease downflow from spring sources. Although our design was not structured to capture this influence, it is important to note that P. morrisoni seemed most abundant near spring vents, par- ticularly within Bubbling Spring pond. If dissolved oxy- gen concentrations nearer spring vents were lower than concentrations away from vents, and springsnails were most abundant near spring vents, we would expect a neg- ative relationship between springsnail abundance and dis- solved oxygen. An ad-hoc analysis showed that sampling stations within 10 m of spring vents in Bubbling Spring pond had a mean dissolved oxygen concentration of 7.27 + 0.127 mg/L while stations greater than 10 m from vents had a mean concentration of 10.77 + 2.79 mg/L (ft = 7.17, df = 38.6, P < 0.0001). This relationship closely resembles the results of our tests for snail presence and density. We therefore have reason to believe that dissolved ox- ygen concentrations and occurrence and density of P. morrisoni were heavily influenced by proximity to spring vents. Regions nearer spring vents may provide environ- mental conditions that better meet the species’ physiolog- ical need. This may be tied to geologic and ecological subterranean processes that determine the nature of water quality near vents. Another factor may be significant diel fluctuations in water quality. Perhaps water further from spring vents exhibits greater variability in extreme con- ditions due to atmospheric influences while water closer to vents is more stable. A sampling methodology de- signed to capture the influence of diel fluctuations could provide important insight. We found differences in mean conductivity concentra- tions in locations where the species was present versus locations where the species was absent. Sites with high and medium levels of conductivity had lower snail den- sities than sites with low conductivity levels. Conductivity is commonly used as an index of dis- solved solids, particularly salts. Salts can play a major role in determining mollusk population density and dis- tribution because they are used in shell formation (Pen- The Veliger, Vol. 48, No. 1 nak, 1989). Though we find the relationship perplexing, lower levels of conductivity seem to be preferred by P. morrisoni. Perhaps lower levels of dissolved salts are more readily assimilated. Or, as with dissolved oxygen, perhaps the relationship is tied to other factors, such as proximity to spring vents and their associated stable en- vironmental conditions. We found that water depth influenced P. morrisoni oc- currence, and mean water depth was greater in regions where the species was absent versus regions where pres- ent. Although depth did not appear to influence spring- snail densities, deeper sites had non-significantly lower snail densities than sites with shallow and medium depths. A larger sample size may have shown this defin- itively. Water depth can substantially influence aquatic ecosys- tems. Sunlight can more readily penetrate shallower re- gions, raising water temperature and boosting photosyn- thetic rates. Deeper waters are more accessible to a di- verse assemblage of organisms, such as fishes, that may act as predators. Although we did not attempt to assess the effect of predation, it is important to note that occur- rence and density of aquatic mollusks can be greatly in- fluenced by the presence of predators, particularly fishes. Experiments conducted by Myler (2000) showed that redbelly tilapia (Tilapia zilli) significantly reduced the food availability for P. bruneauensis and tilapia actively ate individual snails they encountered. Raisanen (1991) reported shells of P. morrisoni in a gut analysis of mos- quitofish (Gambusia affinis) from Bubbling Spring. The potential influence of water depth on the abundance and foraging habits of predaceous fishes within the Oak Creek Springs Complex deserves more attention. Our study constitutes the first empirical effort to define P. morrisoni habitat and should prove useful in assessing the relative suitability of natural or restored spring envi- ronments for the species. It is important, however, to view the structure of an aquatic ecosystem as a complex web of intricate relationships between various biotic and abi- otic variables. Benthic organisms can be affected by a multitude of variables, most of which are extremely dif- ficult, if not impossible, to manipulate or control. As such, caution should be used when actively managing spring environments to provide suitable habitat for en- demic invertebrates. Since it is reasonable to conclude that snail density is indicative of habitat quality (cf. Wan Horne, 1983), we recommend that management actions focus on providing preferred substrates and water depths. This may be ac- complished by ensuring the physical environment facili- tates water velocities that promote the maintenance of gravel and pebble substrates. Specifically, the shear stress of flowing water should effectively transport fine sedi- ments out of the system. A rheocrene environment should provide the most appropriate substrate medium and may serve to boost snail recruitment and density. M. A. Martinez & D. M. Thome, 2005 Although managing water chemistry variables at levels that promote occupancy and high density would be dif- ficult, our results can be used to assess the relative suit- ability of a spring for the species. This may have practical application for possible reintroduction or transplantation efforts. Until now, little information was available to judge the suitability of sites considered for reintroduction or transplantation. Directly manipulating dissolved oxygen and conductiv- ity in a spring to levels most conducive to P. morrisoni occupancy and high density would probably be imprac- tical. Such efforts would likely be costly with low success rates. As such, we suggest the best approach to provide habitat is to maintain springs in their natural rheocrene condition. This is consistent with Hershler and Williams (1996) who suggested that efforts to maintain springsnail populations should focus on the maintenance of natural spring head integrity, which will improve water quality and conserve springsnails. Acknowledgments. We thank the Arizona Game and Fish De- partment for granting access to springs located on their prop- erty. We thank the following individuals for their contribution to this manuscript: Linda Allison, Winnie Chen, Mike Dem- long, Mima Falk, Tom Gatz, Steven Goldsmith, Kathy Good- hart, Ryan Gordon, Jennifer Graves, David Harlow, Suzie Hat- ten, Carrie Marr, Don Metz, Clay Nelson, Mary Richardson, Don Sada, Jeff Sorensen, Roger Sorensen, Larry Stevens, Jerry Stefferud, Sally Stefferud, Arlene Tavizon, and three anony- mous reviewers. LITERATURE CITED ARIZONA GAME AND FISH DEPARTMENT. 1988. Environmental assessment, Page Springs hatchery renovation. Prepared by Planning and Evaluation Branch, Special Services Division and Fisheries Branch, Wildlife Management Division. 78 pp. Brusca, R. C. & G. J. BRusca. 1990. Invertebrates. Sinaur As- sociates, Inc.: Sunderland, Massachusetts. 922 pp. Cummins, K. W. 1962. An evaluation of some techniques for the collection and analysis of benthic samples with special em- phasis on lotic waters. American Midland Naturalist 67:477— 504. Ditton, R. T. 2000. The Ecology of Freshwaters. Cambridge University Press. 509 pp. DUNDEE, D. S., P. H. PHILLIPS & J. D. NEwsom. 1967. Snails on migratory birds. The Nautilus 80(3):89-91. GREESON, P. E. 1982. Why biology in water-quality studies? Pp. A3-—AS5 in P. E. Greeson (ed.), Biota and Biological Princi- ples of the Aquatic Environment. Geological Survey Cir- cular 848-A. HENDRICKSON, D. A. & W. L. MINCKLEY. 1984. Ciénegas-vanish- ing climax communities of the American Southwest. Desert Plants 6(3):130—175 HERSHLER, R. 1984. The hydrobiid snails (Gastropoda: Risso- acea) of the Cuatro Cienegas basin: systematic relationships and ecology of a unique fauna. Journal of the Arizona—Ne- vada Academy of Science 19:61—76. HERSHLER, R. 1990. Pyrgulopsis bruneauensis, a new springsnail (Gastropoda: Hydrobiidae) from the Snake River Plain, Page 15 southern Idaho. Proceedings of the Biological Society of Washington 103:803-8 14. HERSHLER, R. 1994. A review of the North American freshwater snail genus Pyrgulopsis (Hydrobiidae). Smithsonian Contri- butions to Zoology, Number 554. 52 pp. HERSHLER, R. 1998. A systematic review of the hydrobiid snails (Gastropoda: Rissooidea) of the Great Basin, western United States. Part I. Genus Pyrgulopsis. The Veliger 41(1):1—132. HERSHLER, R. & J. J. LANDYE. 1988. Arizona Hydrobiidae (Pro- sobranchia: Rissoacea). Smithsonian Contributions to Zool- ogy, Number 459. 63 pp. HERSHLER, R. & J. E. WILLIAMS. 1996. Conservation strategies for springsnails in the Great Basin: the challenge and the Opportunities. Proceedings of the Desert Fishes Council, 1995 Symposium. XXVII. 1 p. HINTZE, J. L. 2000. NCSS 2000. Statistical system for Windows. Vol. 1-3. NCSS: Kaysville, Utah, USA. LANDYE, J. J. 1973. Status of the inland aquatic and semi-aquatic mollusks of the American southwest. Report submitted to U.S. Department of Interior, Bureau of Sport Fisheries and Wildlife, Office of Rare and Endangered Species, Washing- ton, D.C. 60 pp. LaAnpygE, J. J. 1981. Current status of endangered, threatened, and/or rare mollusks of New Mexico and Arizona. A report submitted to the U.S. Department of Interior, Bureau of Sport Fisheries and Wildlife, Office of Rare and Endangered Species, Albuquerque, New Mexico. 35 pp. McManon, T. E., A. V. ZALE & D. J. ORTH. 1996. Aquatic habitat measurements. Pp. 83-120 in B. R. Murphy & D. W. Willis (eds.), Fisheries Techniques. 2nd ed. American Fisheries So- ciety: Bethesda, Maryland. MLADENKA, G. C. 1992. The ecological life history of the Bru- neau Hot Springs snail Pyrgulopsis bruneauensis. Final Re- port. Stream Ecology Center. Department of Biological Sci- ences. Idaho State University. 116 pp. MLADENKA, G. C. & G. W. MINSHALL. 2001. Variation in the life history and abundance of three populations of Bruneau Hot springsnails Pyrgulopsis bruneauensis. Western North American Naturalist 61(2):204—212. Myter, C. D. 2000. Habitat improvement for an endangered springsnail in southwest Idaho. M.S. Thesis, Idaho State University. 45 p. New, T. R. 1998. Invertebrate Surveys for Conservation. Oxford University Press. 240 pp. O’BrIEN, C. & D. W. BLINN. 1999. The endemic spring snail Pyrgulopsis montezumensis in a high CO, environment: im- portance of extreme chemical habitats as refugia. Freshwater Biology 42:225-—234. PENNAK, R. W. 1989. Freshwater Invertebrates of the United States: Protozoa to Mollusca. John Wiley and Sons, Inc.: New York. 628 pp. RAISANEN, C. 1991. Status survey of four invertebrates of the Page/Bubbling/Lolomai springs/Oak Creek complex. A re- port prepared for USDI Fish and Wildlife Service, Albu- querque, New Mexico. 106 pp. TayLor, D. W. 1987. Fresh-water molluscs from New Mexico and vicinity. New Mexico Bureau of Mines and Minerals 116:1—50. U.S. Fish AND WILDLIFE SERVICE. 2004a. Endangered Species Bulletin. U.S. Department of the Interior, Fish and Wildlife Service. Washington D.C. XXIX(2). 43 pp. U.S. FISH AND WILDLIFE SERVICE. 2004b. Endangered and Threat- ened Wildlife and Plants; Review of Species That Are Can- didates or Proposed for Listing as Endangered or Threat- ened; Annual Notice of Findings on Resubmitted Petitions; Page 16 The Veliger, Vol. 48, No. 1 Annual Description of Progress on Listing Actions; Notice WILLIAMS, J. E., D. B. Bowman, J. E. Brooks, A. A. ECHELLE, of Review; Proposed Rule. Federal Register 69(86):24876— R. J. Epwarps, D. A. HENDRICKSON & J. J. LANDYE. 1985. 24904. Endangered aquatic ecosystems in North American deserts VAN Horne, B. 1983. Density as a misleading indicator of habitat with a list of vanishing fishes of the region. Journal of the quality. Journal of Wildlife Management 47:893-901. Arizona—Nevada Academy of Science 20:1—62. THE VELIGER © CMS, Inc., 2006 The Veliger 48(1):17-25 (June 30, 2006) A Light and Electron Microscopic Study of Pigmented Corpuscles in the Midgut Gland and Feces of Pomacea canaliculata (Caenogastropoda: Ampullariidae) EDUARDO KOCH,* ISRAEL A. VEGA,* EDUARDO A. ALBRECHT* Laboratory of Physiology (IHEM-CONICET), Department of Morphology and Physiology, University of Cuyo, Casilla de Correo 33, M5500 Mendoza, Argentina HUGO H. ORTEGA Laboratorio de Endocrinologia y Tumores Hormonodependientes (LETH-UNL); present address: Laboratorio de Investigaciones Histologicas Aplicadas (FCV-UNL), Santa Fe, Argentina AND ALFREDO CASTRO-VAZQUEZ Laboratory of Physiology (IHEM-CONICET), Department of Morphology and Physiology, University of Cuyo, Casilla de Correo 33, M5500 Mendoza, Argentina Abstract. Pigmented corpuscles (C and K types) and their cellular associations in the midgut gland, as well as similar pigmented corpuscles in snail’s feces and in up to 3-year-old aquarium sediments, were studied. C corpuscles are light brown-greenish spherical bodies (diameter 14 jm) surrounded by a thick, electron dense wall, and containing inner granules and membranes. A rather large variation in the amount of these granules and membranes occurs in C corpuscles, irrespective of whether they were from gland tissue, feces or aquarium sediments. K corpuscles are dark brown, bottle- shaped bodies (36 pm length, 14 wm width) which frequently show a multilamellar structure. All transitional forms between typical C and K corpuscles occur. K corpuscles occur more frequently than C corpuscles in gland tissue but not as much in feces, and are even less frequent in old aquarium sediments. Glandular C corpuscles are contained within vesicles of alveolar columnar cells, and they occur mainly in the basal half of these cells. In the cellular upper half, similar but nude (i.e., without the wall) bodies are seen. On their part, glandular K corpuscles are apparently contained within an extrusion of a columnar cell, which is in turn engulfed by a pyramidal cell. Morphological features of K corpuscles and of their hosting cells indicate that K corpuscles derive from C corpuscles and that the hosting cells partly provide their electron dense layers. Interestingly, the amount of pigmented materials in the midgut gland of females is more than double than that of males. INTRODUCTION and an excretory function to K corpuscles. However, since C corpuscles in the liver string are each packed into a rather thick envelope, and appear as such in the feces, their possible role as carriers of digestive enzymes for extracellular digestion seemed questionable. The present study reexamines the morphology of these corpuscles, as part of a broader program to disclose the nature of these quantitatively important components of the midgut gland. Andrews (1965) published a brief account of the histol- ogy of the midgut gland of Pomacea canaliculata (La- marck, 1822), noticing the existence of two distinct types of intracellular pigmented corpuscles that were freed from glandular cells, and were embedded in what she called the ‘‘liver string’’: a continuous mucous string that was to mix in the gut with the intermittent “‘gastric string”’ of partly digested food. She referred to these corpuscles as MATERIAL anp METHODS “greenish spherules” and “‘brown concretions” (we have referred to them as C and K corpuscles, respectively; Cas- Animals tro- Vazquez et al., 2002). Andrews (1965) also ascribed, on morphological grounds, a digestive-excretory function to C corpuscles Individuals of P. canaliculata were either collected in the Rosedal Lake (Palermo Park, Buenos Aires, Argen- tina) or were laboratory-born descendants from them. Voucher, alcohol-preserved specimens of the original * These authors have contributed equally to this work. population and of the cultured animals were deposited in Page 18 the collection of the Museo Argentino de Ciencias Na- turales (Buenos Aires, Argentina; lots MACN-In 35707 and MACN-In 36046, respectively). They were kept in indoor aquaria, under constant temperature (24°C) and day length (14 hr light and 10 hr dark), and fed with lettuce, supplemented with calcium carbonate. Shell lengths ranged from 30 to 50 mm. Light and Electron Microscopy Fecal droppings of different sizes and shapes were col- lected soon after deposition, and were either studied di- rectly under light microscopy or prepared for electron mi- croscopy (see below). Also, sediment samples taken from aquaria containing P. canaliculata were studied after varying periods (1-36 months) after sampling. Light microscopy preparations were obtained from 5 males and 5 females by cutting 1-2 mm thick slices of the midgut gland with a razor blade from the gland’s sur- face, close to the kidney’s boundary. The samples were fixed in dilute Bouin’s fluid for one week at 4°C. Then, they were placed in 70% ethanol, subsequently dehydrat- ed, embedded in paraffin and sectioned (5 tm). Separate sections were stained with either Harris hematoxylin-eo- sin or iron hematoxylin (Clark, 1981). Digital micrographs (24 bit color format, 640 < 480 pixels) were obtained with a color video camera on a microscope. Morphometric analyses were made using Im- age Pro-Plus 3.0® (Media Cybernetics, Silver Spring, MA, USA) on iron hematoxylin preparations of midgut glands obtained from 5 animals of both sexes (25-50 slides were analyzed per animal). If no sexual differences were apparent, data from both sexes were pooled for pre- sentation. However, a sexual difference was apparent in the relative abundance of C and K corpuscles in iron he- matoxylin preparations. This difference was quantified as the percent of surface occupied by pigmented areas in unstained preparations from both males and females. For this purpose, color segmentation in the chromatic range of both C and K corpuscles was made on 35 microscop- ical fields (0.334 mm? each) of unstained slides from 4 males and 4 females; the surface occupied by the darker areas of C corpuscles (see Results) was separated from that occupied by K corpuscles by filtering pigmented ar- eas smaller than 30 pm’. Differences between means were analyzed with Student’s ¢ test. Also, the glands of adult individuals were processed for electron microscopy. Small pieces of the gland were fixed in 2.5% glutaraldehyde buffered with 0.1 M phos- phate (pH 7.4) and postfixed in 1% osmium-tetroxide and 2% uranyl acetate. Later they were dehydrated in a grad- ed series of ethanol and acetone, embedded in Spurr’s resin, and sectioned with a diamond knife. Ultrathin sec- tions were stained with uranyl acetate and lead citrate and examined in a transmission electron microscope. For to- The Veliger, Vol. 48, No. 1 pographic orientation, 1 «zm sections were stained with 1% toluidine blue. RESULTS General Characteristics of C and K Corpuscles C corpuscles are greenish/light brown spheres (Figure 1B) that usually contain darker, more or less rounded con- densations of varying sizes. In general, their light micro- scopical appearance is similar whether they are obtained from midgut gland tissue, feces or aquarium sediments (up to three years after sampling). However, some distor- tion of C corpuscles in these sediments may be occasion- ally observed (see below). Transmission electron microscopy revealed they are lined by an electron-dense wall (Figure 3). Sometimes, an outer membrane is seen detached from the external wall (Figure 4A, B). These corpuscles contain very fine to coarse granules (Figure 3); coarse granules are mostly associated in clusters that seemingly correspond to the pigmented condensations seen in fresh material. Also, there are irregular inner membranes that are not associ- ated with granules. The relative abundance of these com- ponents is variable among different corpuscles, but this variation cannot be correlated to the origin of the cor- puscles (feces, aquarium sediments or midgut gland sam- ples). K corpuscles in fresh material (Figure IC) are dark brown, bottle or club-shaped bodies. Even though most of them are opaque, some appear composed of multiple, concentric lamellae in which a group of several small, rounded bodies are embedded. Besides those typical K corpuscles there are also corpuscles that appear interme- diate between C and. K corpuscles (Figure 1C). K corpuscles are very abundant in glandular tissue but not in feces or aquarium sediments. Under the electron microscope they appear as either compact or multilamel- lar electron dense bodies (Figure 5) but we have not been able to obtain suitable sections of the inner core of these hard bodies, probably because the embedding resin was not able to adequately penetrate them. C and K Corpuscles in Fecal Droppings and Aquarium Sediments Two types of fecal droppings compose the snail’s fecal stream: (a) sticky strings of thin oval droppings (less than 1 mm thick and several mm in length), and (b) larger fecal droppings of irregular shape (around | mm thick and up to 3 mm long) and not adherent to each other. The thin and sticky strings are composed of only C and K corpuscles (their relative proportions may vary, but C corpuscles are always more abundant than K corpuscles) embedded in a mucous matrix. These strings (Figure 1A) appear similar to what Andrews (1965) described as the “liver string.’ The larger fecal droppings were composed E. Kochet al, 2005 Page 19 Figure 1. A. Two unstained strings of fecal droppings, mainly composed of C corpuscles embedded in a mucous matrix; many darket and larger K corpuscles are seen in the darker string. B. Unstained C corpuscles from a fecal dropping composed of C corpuscles only. C. Unstained glandular corpuscles ranging from the typical C type to the typical K type. The Veliger, Vol. 48, No. 1 Figure 2. Midgut gland alveolar cells associated with C and K corpuscles (iron hematoxylin, scale bars = 15 pm). A. A pyramidal cell, with a large basophilic cytoplasm and a basal nucleus [1], with a prominent nucleolus. An elongated K corpuscle [2] appears contained within the pyramidal cell’s cytoplasm. B. Columnar cells, with small nuclei and nucleoli [3], showing apical bodies [4], probably nude C corpuscles that are being extruded into the gland’s lumen; large cytoplasmic vesicles contain a granular, basophilic | material [5]. C. An alveolus showing basophilic cells with large nuclei [6], as well as columnar cells with small nuclei [7] and a clear vesicular cytoplasm; a walled C corpuscle is seen as a distinct spherule containing inner condensations, probably at the base of another alveolus [8]. D. Higher magnification of the same C corpuscle [8], showing its distinct limits (the wall and the darkly stained inner condensations; similar material is contained in a less distinct spherule [9] which may be a nude C corpuscle; columnar cells nuclei [7] are seen in the surrounding region. of digested food remnants of varying size and appear- ance, and they also contained C and K corpuscles in vary- ing amounts. The sizes of C and K corpuscles were measured in fresh fecal strings (obtained from 7 animals, 25 corpus- cles per animal were measured). The outer diameter of C corpuscles in the liver string was 13.7 + 0.4 um (results of this and all subsequent measurements are expressed as mean + SEM). The length and width of K corpuscles were determined by measuring the rectangles inscribing them (length and width were 35.6 + 1.1 wm and 13.5 + 0.4 zm, respectively). The external shape of some C corpuscles in aquarium sediments was sometimes distorted, adopting semilunar or even more irregular shapes. Cellular Associations of C and K Corpuscles in the Midgut Gland The gland of P. canaliculata is composed of elongated irregular alveoli (135.6 + 0.6 wm in diameter), the epi- thelium of which (60.8 + 0.6 1m in height) is formed by two cell types (pyramidal and columnar) that line a lumen of irregular width (Figure 2A—C). Columnar cells appear in iron hematoxylin prepara- tions as vesicle containing cells, with a rather small nu- cleus (4.9 + 0.4 wm in diameter) and a nucleolus. Gen- erally, the nucleus is placed laterally, in the lower half of the cell. As noted by Andrews (1965), the height of co- lumnar cells is similar in all the alveoli of the same in- dividual, but it varies among individuals, what that author E. Koch et al., 2005 Page 21 Figure 3. Electron micrographs (scale bars = | jm) of extra- and intracellular C corpuscles. A. C corpuscle in a fecal dropping; the nearby small electron dense bodies are cocci. B. C corpuscle in a 36-month-old aquarium sediment. C. A more dense C corpuscle in the same old aquarium sediment. D. C corpuscle contained within a glandular cell. [1] outer wall; [2] inner membranes; [3] coarse granules; [4] vesicle surrounding the corpuscle; [5] glandular cell cytoplasm; [6] condensation of fine granules below the outer wall. attributed to different functional digestive or excretory states. When the cells are high, their apex is frequently dome- shaped, and clear globules or vesicles appear protruding into the lumen, as if a process of apocrine secretion was going on (Figure 2B). Sometimes the vesicles appear empty (Figure 2C), especially when iron hematoxylin preparations are thoroughly differentiated. However, in many cases, they appear filled with stainable material of varying appearance (Figure 2A, B). In many other cases, particularly in the basal third of the epithelial cells, the corpuscle contained within the vesicle appears surround- ed by a wall (Figure 2C, D); these walled corpuscles are frequently pigmented (greenish/brownish in color) and can be recognized even in unstained preparations. The walled, pigmented corpuscles seem identical to fecal C corpuscles, because of their appearance, color and size (outer diameter 1m of corpuscle-containing vesicles was 12.3 + 0.4). Electron microscopy of the basal region of the colum- nar cells shows many C corpuscles (Figure 3) each sur- rounded by an electron-dense wall and contained within a large vesicle. Their inner structure is in all respects similar to that of C corpuscles in either feces or sedi- ments. Along with the walled C corpuscles, other mem- brane-bound bodies of variable size and content (similar The Veliger, Vol. 48, No. Figure 4. A. The wall of a fecal C corpuscle (scale bar = 0.2 wm) showing the outer membrane (4) which is detached from it; the electron dense structures outside the C corpuscle are cocci. B. Outer membrane (<) detached from the wall of a C corpuscle contained within a glandular cell (scale bar = 0.2 wm); the lipid bilayer can be recognized. C. A large body (scale bar = 2 ym), probably a nude C corpuscle that is located close to the alveolar lumen [1] where microvilli are seen [2]. Two similar smaller bodies appear as either fusing with the larger body, or alternatively, being split by new membrane formation [3]. Coarse granules [4] are seen in these bodies, both within buds protruding on the outer surface, and associated with numerous finer granules [5]. Also, an array of inner membranes is seen, particularly in the larger body [6]. The inset shows the double membrane lining this body (1.6 times the initial micrograph). E. Koch et al., 2005 Figure 5. Electron micrographs (scale bars = 2 pm) of K cor- puscles and associated structures. A. A large pyramidal cell nu- cleus [1] of a cell with a well developed rough endoplasmic reticulum (RER) [2]. The nearby K [3] corpuscle is surrounded, however, by a thin cytoplasmic band from a different cell [4]. B. Page 23 to that of walled C corpuscles) are present, especially in the upper region of columnar cells (Figure 4). A double membrane can be recognized lining some of these bodies, which sometimes appear splitting. Budding structures containing a single large electron-dense granule can also be seen (Figure 4). Pyramidal cells are less frequent than the columnar cells described above. They are large basophilic cells with a wide base and a large and basal nucleus (8.5 + 0.5 wm in diameter) with a prominent nucleolus (Figure 2A). The nucleus is located close to the basal membrane. Dark cor- puscles identical to fecal K corpuscles appear associated to these cells in light microscopy preparations. Each of them seems to be contained within the cytoplasm of py- ramidal cells, usually with the wider base near the basal membrane and the narrower neck close to the lumen. The dimensions of such large structures are difficult to assess in tissue sections, where they appear sectioned in all pos- sible spatial planes. We estimated length as the maximum diameter of those corpuscles in which the ratio between the maximum and minimum diameter was 1.5 or more, and width as the mean diameter of those corpuscles in which the maximum/minimum diameter ratio was less than 1.2. Under these conventions the length of K parti- cles contained within pyramidal cells was 22.6 + 1.2 wm and width was 15.0 + 0.4 pm. Electron microscopy of typical K corpuscles shows them contained within a large vesicle (Figure 5). This vesicle is usually lined by a narrow cytoplasmic band of varying electron density where mitochondria may be found. Particles of high electron density are deposited on the surface of the K corpuscle, coming from the cyto- plasmic band surrounding it. The whole (i.e., the vesicle containing the K corpuscle and the narrow band of cy- toplasm) is in turn surrounded by cytoplasm with a well developed rough endoplasmic reticulum (RER); when a nucleus is seen in the surrounding RER-bearing cyto- plasm, it is always a large one (Figure 5). Since these large nuclei are likely to be those of pyramidal cells, K corpuscles would not actually be contained within pyra- midal cells, but within the cytoplasm of a different cell (seemingly an extrusion of a columnar cell), which is in turn engulfed by a pyramidal cell. = A multilamellar K corpuscle [5] close to RER-bearing cytoplasm [6]; however, the corpuscle is also contained within a cytoplas- mic band from another, more electron dense cell [7]. Clumps of high electron density material are contained within the same ves- icle as the K corpuscle, and appear as being deposited on it. C. The lower micrograph shows the apex of a stereocilia-bearing cell containing a K corpuscle that is not surrounded by any cy- toplasmic band. Clumps of an electron-dense material seem to be being absorbed in the stereocilia and appear to be being de- posited on the K corpuscle. Page 24 Table 1 Pigmented areas in midgut glands of male and female P. canaliculata. C corpuscles* (%) 0.18 5.15 + 0.44 0.34 11.88 + 2.28 K corpuscles** (%) Males 0.78 Females 1.92 I+ I+ * Pigmented areas that were in the chromatic range of C and K corpuscles and that were smaller than 30 jm’, expressed as percent of the tissue section occupied by them; they correspond to the total area occupied by the darker areas of C corpuscles (i.e., a smaller area than the one occupied by whole C corpus- cles). Significantly different by gender (Student’s f test, P < 0.01). ** Pigmented areas that were in the chromatic range of C and K corpuscles and were larger than 30 wm’, expressed as percent of the tissue section occupied by them; they correspond to the total area occupied by K corpuscles. Significantly different by gender (Student’s ¢ test, P < 0.01). Sexual Differences in the Amount of Pigmented Corpuscles Midgut glands of females in light microscopy prepa- rations appeared to have a greater amount of pigmented material than those of males. Therefore the relative abun- dance of pigmented corpuscles in males and females was quantified in unstained preparations as the percent of the section surface occupied by pigmented areas. Although average pigment density is higher in K than in C corpus- cles, the chromatic range was continuous between both types of corpuscles (i.e., dark areas of C corpuscles over- lap with light areas in K corpuscles). Therefore, they were separated by estimating the total area occupied by dots smaller than 30 wm? (which correspond only to the pig- ment condensations within C corpuscles, and not to whole C corpuscles). Results are summarized in Table 1. The relative occupancy of the female midgut gland by C cor- puscles (defined as explained above) and K corpuscles was approximately 2.4 times that in males (Student’s ¢ test, P < 0.01). DISCUSSION Pigmented “‘spherioles” in the midgut gland of gastro- pods have been recognized for more than a century. They have been regarded as containing “‘chlorophyllous pig- ments” derived from food, and/or as having an excretory function (see MacMunn, 1900, for early references). Meenakshi (1955) was probably the first to notice them in an ampullariid snail (Pila virens (Olivier, 1804)). The present study of Pomacea canaliculata has shown some interesting and unexpected morphological features of both types of pigmented corpuscles that Andrews (1965) described in alveolar cells of the midgut gland of this species. As predicted by Andrews (1965) glandular C corpuscles are associated with alveolar columnar cells The Veliger, Vol. 48, No. 1 (which she calls “‘secretory and digestive cells”). They are granule-containing bodies surrounded by an electron dense wall, and are located within membrane vesicles of these cells. A membrane system composed of both irreg- ular inner membranes and an outer lining membrane (lo- cated beneath the outer wall) could also be seen in some C corpuscles. No evidence of a nucleus was found in any case. Bodies similar to C corpuscles except that they were not lined by the outer wall, could also be seen contained within membrane vesicles, so that these corpuscles ap- peared lined by a double membrane. Since walled C cor- puscles are not usually seen in the apical portion of co- lumnar cells, and they are the only ones observed in the feces, the nude forms must either be digested after being released into the glandular lumen or acquire the wall dur- ing their passage through the gut. Although K corpuscles appear contained within alve- olar pyramidal cells (‘excretory cells,’ Andrews, 1965) in light microscopic preparations, electron microscopy has shown they are actually contained within an extrusion of a cell with a small nucleus (i.e., a columnar cell) and that this extrusion is in turn engulfed by a pyramidal cell. K corpuscles occur more frequently than C corpuscles in glandular tissue, while C corpuscles are more frequent in the feces, which suggests that the rate of formation and elimination of K corpuscles may be very low. C corpuscles that were essentially similar to glandular corpuscles were also observed in feces and in old aquar- ium sediments up to three years after sampling. A smaller number of K corpuscles is also eliminated in the feces by P. canaliculata, and they appear in aquarium sediments, but they tend to disappear with time. The current results may be interpreted to mean that C corpuscles are not digestive enzyme carriers but the anu- clear, thick-walled cells of a symbiont, which might also live outside the snail. K corpuscles may be interpreted as the cystic forms of that symbiont. The detection of sig- nificant amounts of DNA in both types of corpuscles (Castro-Vazquez et al., 2002) also favors this interpreta- tion. This possibility should be tested with molecular bi- ology techniques to determine the phylogenetic affinities of corpuscular DNA. Another possible interpretation is that C corpuscles might be large residual bodies of intracellular digestion. The great variability we have observed in the content of C corpuscles might favor this hypothesis. However, the significance of K corpuscles, which seem to be deriva- tives of C corpuscles, as well as the presence of DNA in both types of corpuscles would be left unexplained by a residual bodies hypothesis. We have not yet any testable hypothesis for explaining the larger amount of pigmented material present in the midgut glands of female snails, than in those of male snails. If both C and K corpuscles finally prove to be morphs of a symbiont, some nutritional advantage related to the requirements of the high reproductive investment E. Koch et al., 2005 of female P. canaliculata (Albrecht et al., 1999, 2004) will have to be explored. Acknowledgments. This work was supported by grants from CONICET, ANPCyT, and the National University of Cuyo. The generous help of Professor Beatriz C. Winik (National University of Tucuman, Argentina) and the criticisms of Professor Luis S. Mayorga (National University of Cuyo, Argentina) are gratefully acknowledged. LITERATURE CITED ALBRECHT, E. A., N. B. CARRENO & A. CASTRO-VAZQUEZ. 1999. Quantitative study of environmental factors influencing the seasonal onset of reproductive behavior in the South Amer- ican apple-snail Pomacea canaliculata (Prosobranchia: Am- pullariidae). Journal of Molluscan Studies 65:241—250. ALBRECHT, E. A., E. Kocu, N. B. CARRENO & A. CASTRO-VAZ- QUEZ. 2004. Control of the seasonal arrest of copulation and spawning in the applesnail Pomacea canaliculata (Proso- Page 25 branchia: Ampullariidae): differential effects of food avail- ability, water temperature, and day length. The Veliger 47: 147-152. ANDREWS, E. B. 1965. The functional anatomy of the gut of the prosobranch Pomacea canaliculata and some other pilids. Proceedings of the Zoological Society of London 145:19— 36. CASTRO-V AZQUEZ, A., E. A. ALBRECHT, I. A. VEGA, E. KocH & C. GAMARRA-LUQUES. 2002. Pigmented corpuscles in the midgut gland of Pomacea canaliculata and other neotropical apple-snails (Prosobranchia, Ampullariidae): a possible sym- biotic association. Biocell 26:101—109. CLARK, G. 1981. Staining Procedures. 4th ed. Williams & Wil- kins: Baltimore, MD. MacMunn, C. A. 1900. On the gastric gland of Mollusca and Decapod Crustacea: its structure and functions. Philosophi- cal Transactions of the Royal Society of London. Series B, Biological Sciences 193:1—38. MEENAKSHI, V. R. 1955. The excretory spherioles in the digestive gland of Pila virens. Journal of Animal Morphology & Physiology 3:75-78. THE VEBLIGSEE © CMS, Inc., 2006 The Veliger 48(1):26—45 (June 30, 2006) Diversity and Abundance of Tropical American Scallops (Bivalvia: Pectinidae) from Opposite Sides of the Central American Isthmus J. TRAVIS SMITH!', JEREMY B. C. JACKSON!?, ann HELENA FORTUNATO? 'Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093-0244, USA *Center for Tropical Paleoecology and Archeology, Smithsonian Tropical Research Institute, Box 2072, Balboa, Republic of Panama Abstract. There is confusion about the comparative diversity of mollusks on opposite sides of the Isthmus of Panama due to inadequate sampling and contrasting patterns of diversity for different molluscan taxa. We report here on the occurrence of scallops (Bivalvia: Pectinidae) from extensive new dredge sample collections from the Gulf of Panama and Gulf of Chiriqui in the Eastern Pacific and from the San Blas archipelago to the Cochinos Cays in the Gulf of Honduras in the southwestern Caribbean. The collections contain more than 8000 specimens of 33 species from 213 collections. These include 22 Caribbean species and 11 Eastern Pacific species. However, the average abundance of scallops per collection is much higher in the Eastern Pacific so that the average number of species per collection was similar in the two oceans. This discrepancy in abundance is the principal reason previous workers have erroneously concluded that species diversity is equal or even greater in the Eastern Pacific than the Caribbean. Numbers of scallop species at the seven different Caribbean localities sampled average about one and one half times higher than the two regions in the Eastern Pacific, and the total differences in species richness are two times higher for all the regions combined. Most scallop species were common to abundant and scallop species do not exhibit a log series or log normal pattern of relative abundance. However, we found eight previously undescribed species, two in the Eastern Pacific and six in the Caribbean. These appear to be geminate species and are indistinguishable, pending detailed morphological study, from species occurring in the opposite ocean. These new species are all rare but typically occurred in sufficient abundance and at numerous localities so that their occurrence is not in question. INTRODUCTION The rise of the lower Central American Isthmus divided the once continuous tropical American ocean into two very different realms (Birkeland, 1977, 1987; Coates et al., 1996; D’Croz and Robertson, 1997; Jackson & D’Croz, 1998). Formation of the Isthmus occurred over about 20 million years (Coates et al., 2003) and the final separation of the oceans around 3.5 to 3.0 million years ago (Coates & Obando, 1996). Coastal environments on the two sides of the Isthmus are very different (Birkeland, 1977, 1987; Jackson & D’Croz, 1998). The tropical East- ern Pacific exhibits strong seasonal and inter-annual fluc- tuations in temperature and primary production associat- ed with upwelling and El Nifio events. Primary produc- tivity of phytoplankton is great but coral reefs are poorly developed and seagrasses absent. In contrast, the tropical Western Atlantic exhibits much smaller seasonal and in- ter-annual variability, low planktonic productivity, and extensive development of coral reefs and seagrass mead- OWS. The isolation of the oceans also resulted in widely di- verging patterns of evolution and taxonomic diversity among major taxa that were formerly quite similar across the developing Isthmus (Vermeij, 1978, 1993; Lessios, 1990; Jackson et al., 1993, 1996; Knowlton et al., 1993; Knowlton and Weight, 1998; Budd, 2000). Numbers of species of reef corals (Veron, 2000), cheilostome bryo- zoans (Cheetham & Jackson, 2000), and benthic forami- nifera (Buzas & Culver, 1991; Collins, 1999) are consid- erably greater in the Western Atlantic than the Eastern Pacific, whereas crustaceans (Jones & Hasson, 1985) and echinoderms (Chesher, 1972) differ little across the Isth- mus. The diversity patterns for mollusks have been the sub- ject of much confusion and debate because of great dif- ferences in sampling effort and taxonomic study. Wood- ring (1966) and subsequently others (Stanley & Camp- bell, 1981; Vermeij & Petuch, 1986; Petuch, 1995) con- cluded that the Western Atlantic fauna had suffered high extinction during the Pliocene that reduced diversity com- pared to the Eastern Pacific. However, more recent studies demonstrate that high extinction was balanced by high origination (Allmon et al., 1993, 1996; Jackson et al., 1993, 1999) and that the numbers of species in the two oceans are approximately the same (Roy et al., 2000). In contrast, the diversity patterns of lower taxonomic levels exhibit great variation across the Isthmus. For ex- ample, gastropods of the Strombina Group have much higher diversity in the Eastern Pacific than the Western J. T. Smith et al., 2005 Table 1 Previous studies covering the Caribbean, Gulf of Mexico, and Eastern Pacific regions. Pacific studies Taxa Grau, 1959 g) Olsson, 1961 9 Keen, 1971 9 Previously described species 9 This study 11 Caribbean studies Taxa Olsson and McGinty, 1958 5 Abott, 1958 7 Bayer et al., 1970 15 Waller, 1973 18 Vokes and Vokes, 1983 12 Rios, 1985 10 Cahill, 1990 15 Merlano and Hegedus, 1994 16 Abbott and Morris, 1995 13 Mikkelsen and Bieler, 2000 22 Redfern, 2001 11 Previously described species 25 This study 25 Atlantic (Jung, 1989; Jackson et al., 1993, 1996; Fortun- ato, 1998). Similarly, the bivalve genus Chione is ap- proximately twice as diverse in the eastern Pacific (Roop- narine, 2001). In contrast, the scallops in the Family Pec- tinidae are more diverse in the Western Atlantic (Table i) Mollusks of the tropical Eastern Pacific have been sam- pled more extensively than tropical Western Atlantic mol- lusks. There are no major compendia of the tropical West- ern Atlantic fauna comparable to those for the tropical Eastern Pacific (e.g., Grau, 1959; Olson, 1961; Keen, 1971; Coan et al., 2000); although numerous studies doc- ument the faunas of more limited areas such as the Ba- hamas (Redfern, 2001), Bermuda (Waller, 1973), Brazil (Rios, 1985), Colombia (Merlano & Hegedus, 1994), Florida Keys (Mikkelsen & Bieler, 2000), Jamaica (Hum- frey, 1975), Panama (Olsson & McGinty, 1958; Radwin, 1969; Bayer et al., 1970), Cuba (Espinosa et al., 1994), and the Yucatan Peninsula (Ekdale, 1974; Vokes & Vo- kes, 1983). Recent tropical Eastern Pacific scallops have been de- scribed in three monographs (Grau, 1959; Keen, 1971; Olsson, 1961) each of which described all nine known species. In contrast, the Family as a whole has not been fully documented in any one study for the Western At- lantic although different genera have been described in detail including Argopecten (Waller, 1969), Nodipecten (Smith, 1991), and the “‘chlamid”’ genera Caribachlamys, Laevichlamys, and Spathochlamys (Waller, 1993). Twen- ty-five species of scallops have been described from the tropical Western Atlantic but no one published report in- Page 27 cludes all the species and the average number of species per paper is 13. The highest reported diversity in one region is 22 from the Florida Keys (Mikkelsen & Bieler, 2000), and this was a compilation based on museum col- lections, private collections, and publications. Here we describe the diversity and abundance of scal- lops from opposite sides of the Central American Isthmus obtained by extensive dredging along the Pacific coast of Panama and the Caribbean coast of Panama, Nicaragua, and Honduras. The very large numbers of samples and specimens allowed us to evaluate possible effects of sam- pling bias and to describe patterns of species diversity and relative abundance with confidence. MATERIALS AnD METHODS All samples were obtained by Helena Fortunato from 1995 to 1998 as part of the Panama Paleontology Project using a bottom dredge and the research vessel RV Urraca of the Smithsonian Tropical Research Institute. The dredges were built at STRI and ranged in size from 27 to 29 inches in width, 17 to 27 inches in height, trailing a net with | inch mesh. The dredges were towed for 5 to 20 minutes depending on bottom conditions and depth and were usually brought up clogged and full of sedi- ment. The 79 samples from the Eastern Pacific were ob- tained from depths of 6 to 380 meters depth and the 150 Caribbean samples from 7 to 538 meters. However, most of the samples from both oceans were from less than 100 meters depth. The geographic locations of all the samples are shown in Figure | and the details of locations, depth, and bottom characteristics for all the samples can be found at the PPP website (http://www. fiu.edu/~collinsl/ index.html). The samples were washed and sieved on deck using 8 mm and 2 mm mesh. Samples were sorted at STRI and all bivalves identified to genus or subgenus before ship- ment to the Scripps Institution of Oceanography. All scal- lops were identified to species by the first author. Additional material examined for taxonomic reference included scallops from the Gibson-Smith collections of Venezuelan mollusks now housed at the Naturhistorisches Museum in Basel Switzerland (NMB), and from the first author’s collections from deposits in the Enriquillo Valley in southwestern Dominican Republic and Bocas del Toro, Panama. Material from these additional collections was not used in analyses of diversity and abundance. Diversity was measured as the number of species (rich- ness), the Shannon- Weiner index of diversity H, calculated as H = —% pjlog p,, and Fisher’s Alpha (a) as N/S = (eS — 1)/(S/a). The latter is a best-fit solution for a. Both metrics were calculated using the STATPOD package for the statistics software R (Johnson & McCormick, 1999). TAXONOMY AnD SYSTEMATICS Our goal was to describe patterns of species occurrences and abundance across the Isthmus without attempting Page 28 The Veliger, Vol. 48, No. 1 Figure 1. Locality maps. Central map shows the geographic locations of the localities used in this study. Surrounding maps show regional localities for (A) Cochinos Cays, Honduras, (B) Mosquito Cays, Nicaragua, (C) Bocas del Toro, Panama, (D) San Blas, Panama, (E) Gulf of Chiriqui, Panama, and (F) Gulf of Panama, Panama. Small letters on the Bocas del Toro map (C) depict the regions used in the study. These are (a) Almirante Bay, (b) Chiriqui Lagoon, (c) Bocas del Toro, and (d) Gulf of Mosquitoes. any systematic revision of higher taxonomic categories that would be inappropriate without thorough examina- tion of material from outside the region of study. In gen- eral, we followed the systematic framework of Waller (1969, 1986, 1991, 1993) that has received strong sup- port from independent molecular genetic data based on mitochondrial cytochrome c oxidase COI (Matsumoto & Hayami, 2000) and mitochondrial 16s and 12S rRNA genes (Barucca et al., 2004). Additional sources for taxa not covered in Waller’s work include Grau (1959), Ols- son (1961), Keen (1971), Moore (1984), Rios (1985), Smith (1991), Abbott and Morris (1995), and Coan et al. (2000). We did not subdivide genera into subgenera because of inconsistent usage in the literature, and because species within the different genera could be consistently and un- J. T. Smith et al., 2005 ambiguously distinguished on the basis of one or more characters regardless of their subgeneric classification. The only exception is Pseudamussium (Peplum) as tra- ditionally used for the species P. (P.) fasciculatum (Hinds, 1845) (Figures 21, J, M, N). Nodipecten has been considered both a subgenus of Lyropecten (Keen, 1971; Jackson et al., 1999) and as a separate genus (Smith, 1991; Abbott & Morris, 1995; Coan et al., 2000). Nodi- pecten can be separated from species of Lyropecten based on the ribbing pattern (Smith, 1991). Members of the ge- nus Lyropecten have a left valve ribbing pattern of r- RrrRerrRr or rNrrNerrNr where r represents a rib, R a key or more pronounced rib, N represents a key rib with nodes, and Ne signifies the central, noded rib following Smith (1991). In Nodipecten this arrangement is rRr- RerRr or rNrNerNr. The species Nodipecten arthriticus (Reeve, 1853) (Figures 3D, E) and Nodipecten sp. G (Fig- ure 3C) are problematic in that they have the ribbing pat- tern rNrrNerNr, which is intermediate to the characteris- tics of Lyropecten and Nodipecten. However, pending systematic revision, we have placed species with this rib- bing pattern in the genus Nodipecten following Smith (1991) and Coan et al. (2000). Pacipecten has been considered as a subgenus of both Leptopecten (Keen, 1971) and Aequipecten (Olsson 1961), and as a separate genus (Moore, 1984). Olsson (1961) originally described Pacipecten as a subgenus of Aequipecten. Later workers have gone back and forth treating the group as a subgenus or a genus. Species of Pacipecten and Leptopecten appear to form a clade and can be consistently separated from other groups based on their hinge morphology. In both genera there are two pairs of hinge teeth on the right valve and the anterior resilial tooth is the dominant tooth (Figure 4A). The ge- nus Pacipecten can be separated from Leptopecten by the very fine or absent concentric lirae, making the shell ap- pear almost smooth, and the absence of secondary or ter- tiary ribbing (Figure 5C). In the genus Leptopecten the concentric lirae are strong, often creating a flange-like appearance, and secondary or tertiary ribs are present in all of the tropical American species, although not in a consistent manner (Figure 5A, B). The genus Euvola is the most problematic. Waller (1991) combined the living tropical American species previously assigned to the genera Oppenheimopecten, Flabellipecten, and Amusium into the genus Euvola based on observations that the species in question share certain morphological traits, and are quite certainly not members of the genera to which they have traditionally been as- signed. While there are morphologic characters that ap- parently separate the species herein assigned to this genus into identifiable groups, the systematic approach of Wal- ler has been followed here pending further work. We used open nomenclature for the species Pectinid A lineolaris (Lamarck, 1819) (Figure 6A, B). This species Page 29 has most recently been assigned to the genus Argopecten (Waller, 1969, 1991). The morphology of the hinge teeth indicates a close relationship with this genus. However, the early dissoconch microstructure of the left valve is unique to this species among those observed in these col- lections. In members of the genus Argopecten, as in all of those genera in the “‘Aequipecten”’ group observed in this study—Lindapecten, Pacipecten, and Leptopecten— a microstructure consisting of coarse pitting begins very early in the early dissoconch stage (Figure 7A, B). In Pectinid A the onset of this structure is delayed or ex- tremely reduced (Figure 7C, D). In this case, as in the genera discussed above, the generic placement is not cru- cial to the analyses presented here. The diversity and rar- ity data presented are all based on species level identifi- cations and are not examined at the genus level. Species were identified using easily observed morpho- logic characters. Examples of all species identified and used in the analyses presented here are illustrated in Fig- ures 2, 3, 6, 9-13. These figures also include several specimens that were used for comparison with observed species. The most readily observed character is valve symmetry. Species traditionally placed in the subfamily Pectininae have highly asymmetrical valves. The left (up- per) valve is generally flat or even concave and the right (lower) valve is convex (Figure 8C, D). In all other spe- cies in the family, the valves are equal to sub-equal in convexity (Figure 8A, B). However, recent molecular work has questioned of the validity of this character for defining sub-familial groups within the Pectinidae (Frischer et al., 1998; Canapa et al., 2000; Steiner & Muller, 1996; Barucca et al., 2003). This apparent dis- connect between traditional, easily observed morphologic characters and phylogenetic relationships based on mo- lecular data is the primary reason for our decision to an- alyze diversity only at the species level pending further systematic work on the group to sort out higher level taxonomic relationships. Hinge teeth are also an important taxonomic character as discussed above in regards to Pacipecten and Lepto- pecten. Waller (1986, 1991) presented a consistent iden- tification and nomenclatural scheme for pecten hinge teeth, also called crura. The primary morphologic differ- ences in hinge teeth relate to number of pairs and domi- nance of the teeth, illustrated in Figure 4, which differs depending on the left and right valves of the taxon in question. The remaining characters used for identification of species are rib count, presence or absence of secondary or tertiary ribbing, presence and strength of concentric lirae, and pattern of rib dominance and ribs with nodes. In this study we have identified several taxa that are heretofore undescribed and are designated informally as species A, B, etc. In all but two cases these taxa are similar to species known from the opposite ocean and Page 30 The Veliger, Vol. 48, No. Figure 2. Spathochlamys, Pseudamussium (Peplum), and Bractechlamys. (A) Spathochlamys benedicti (CTPA 540-B-52, Ivh = 1 mm), (B) S. benedicti (CTPA 493-B-124, rvh = 15.79 mm), (C, D) S. cf vaginula (jts 06-B-11, (C) Ilvh = 16.27 mm, (D) rvh = 1 mm), (E, F) S. vestalis (CTPA 399-B-146, (E) Ivh = 12.36 mm, (F) rvh = 13.13 mm), (G, H) S. sp. A (CTPA 538-B-101, (G) lvh 14.79 mm, (H) rvh = 14.08 mm), (1, J) Pseudamussium (Peplum) fasciculatum (CTPA 415-B-72, (I) lvh = 29.81 mm, (J) rvh = 28. mm), (K, L) Bractechlamys antillarum (CTPA 431-B-72, (K) lvh = 16.35 mm, (L) rvh = 18.55 mm), (M) P. (P.) sp. D (CTPA 52 5 B69, lvh = 18.87 mm), (N) P. (P.) sp. D (CTPA 338-B-85, rvh = 28.0 mm), (O) B. sp. H (CTPA 362-B-1, lvh = 14.09 mm), (P) B sp. H (CTPA 412-B-1, rvh = 14.04 mm). wp Nn ail 1 Ww t Pon ll 1 J. T. Smith et al., 2005 Page 31] Figure 3. Nodpipecten. (A) Nodipecten nodosus (jts 06.13-B-13, lvh = 85.75 mm), (B) N. nodosus (CTPA 403-B-84, rvh = 66.81 mm), (C) N. sp. G. (CTPA 494-B-57, lvh = 15.36 mm), (D) N. arthriticus (CTPA 403-B-45, Ivh = 97.37 mm), (E) N. arthriticus (CTPA 389-B-84, rvh = 53.05 mm). may be geminate species pairs. The two undescribed spe- cies that are not considered geminate species are Euvola sp. cf. E. raveneli (Dall, 1898) (Figure 9F), which is rep- resented by very few identifiable specimens, and Cari- bachlamys sp. cf. C. mildredae (Bayer, 1941) (Figure 10A, B). The latter species was found by the first author while snorkeling in Bocas del Toro but not in any of the dredge samples, and is therefore not included in the anal- yses of diversity. A final species, tentatively identified as Euvola cf. laurenti (Gmelin, 1791), was not included in The Veliger, Vol. 48, No. 1 Figure 4. [lustration of the described hinge morphologies. Two pairs of hinge teeth with the anterior resilial tooth dominant (A). Two pairs of hinge teeth with the resilial teeth dominant and extended (B). Two pairs of hinge teeth with no dominant teeth (C). More than two pairs (3 in this case) of hinge teeth (D). Specimens shown are (A) Pacipecten tumbezensis (CTPA 381- B-70, hl = 25.54 mm), (B) Argopecten gibbus (NMB 17662, hl = 31.52), (C) Caribachlamys cf. mildredae (jts 11-B-1, hl = 14.32), and (D) Nodipecten nodosus (NMB G_ 17477, hl 64.34). Terminology follows Waller (1986, 1991, 1993). this study because it occurred as a single fragment from one sample in the Eastern Pacific. PATTERNS or SPECIES DIVERSITY We obtained 3915 specimens of 11 species of scallops in 74 samples from the Eastern Pacific and 4434 specimens of 22 species in 139 samples from the Caribbean (Table 2). The number of living specimens was less than 0.1% of the total, so these results are based on time-averaged assemblages representing hundreds to thousands of years (Kidwell, 2002a). Death assemblages have been shown Figure 5. Shell morphology of Leptopecten and Pacipecten. The characteristics of Leptopecten (A, B) are strong concentric lamellae and the presence, in most taxa, of secondary ribbing, and in Pacipecten (C) are very fine concentric lamellae and ab- sence of secondary or tertiary ribbing. Specimens shown are (A) Leptopecten biolleyi (CTPA 387-B-151), (B) Leptopecten bavayi (CTPA 577-B-34), and (C) Pacipecten linki (CTPA 458-B-100). to faithfully represent the relative abundance of the local fauna (Kidwell, 2001, 2002a). This is particularly true when the focus is on larger mesh sizes (> 1.5 mm) as is the case in this study (Kidwell, 2002b). Collector’s curves of numbers of species found as a function of numbers of specimens or samples level off well before all the samples are included so that the differences in diversity are robust (Figure 14). However, the abundance of specimens per Jo . Svan Ge al, AUTOS Page 33 Figure 6. Argopecten and Pectinid A. (A, B) PectinidA l/ineolaris (NMB G 17478, both valves height = 39.69 mm), (C) Argopecten gibbus (CTPA 326-B-25, lvh = 19.57 mm), (D) A. gibbus (CTPA 336-B-47, rvh = 15.72 mm), (E, F) A. ventricosus (CTPA 399-B- 27, (E) lvh = 16.70 mm, (F) rvh = 13.02 mm). dredge sample was much greater in the Pacific collections (2 X 2 contingency table, chi square = 556.72, P< 0.0001). Nearly twice the number of samples in the Ca- ribbean yielded only 12% more specimens than were col- lected in the Pacific. There are two important consequenc- es of these differences in abundance between the oceans. First, the average number of species per locality is about four in both oceans, despite the much greater overall di- versity in the Caribbean (Figure 15A). Second, the sam- pling curves are slightly flatter for the Eastern Pacific collections. More specimens per locality equate to higher local species richness and more complete sampling with lower effort. In the Eastern Pacific, numbers of species were lower in the Gulf of Panama than the Gulf of Chiriqui (Table 3). There were only small differences in the Shannon- Weiner Index (H) and Fisher’s Alpha (a) diversity mea- sures between these two regions. Diversity in the Gulf of Chiriqui was slightly lower using H and slightly higher using a. We found all nine of the previously described species from the Eastern Pacific, although not always in both regions. The two additional species reported here are undescribed and are apparently geminate species (Table 4). Lindapecten sp. B (Figure 11C, D) was found in both the Gulf of Panama and Gulf of Chiriqui, but Bractech- lamys sp. H (Figure 20, P), was found only in the Gulf of Chiriqui. Lindapecten sp. B is virtually indistinguish- able from L. acanthodes (Dall, 1925) (i1A, B) in the Caribbean as is Bractechlamys sp. H from B. antillarum (Recluz, 1853) (Figure 2K, L) in the Caribbean. Both species were identified from well-preserved complete specimens collected at multiple localities (Table 2). Sampling completeness was not as good in the Carib- bean as in the Eastern Pacific. All of the Caribbean re- gions except Bocas del Toro contained only two thirds or less of the total Caribbean species collected. Species rich- ness ranged from 14 to 17 species for all the regions except Bocas del Toro (Table 3), and sampling curves were indistinguishable except for the latter region. The Shannon-Weiner Index (H) is highest (H > 1.9) in the Bocas del Toro, San Blas, Almirante Bay, and Cochinos Cays regions. H was lowest (H < 1.8) in the Mosquito Cays, Gulf of Mosquitoes, and Chiriqui Lagoon regions. There is very little difference among these groups. Fish- er’s Alpha (a) was highest (a > 3.6) in the Bocas del Toro, Gulf of Mosquitoes, and Los Cochinos regions. AI- pha was lowest (a < 3.1) in the Chiriqui Lagoon, Mos- quito Cays, and Almirante Bay regions. The San Blas region was intermediate between these groupings. We found 6 new species in the Caribbean samples, all Page 34 The Veliger, Vol. 48, No. 1 “HV [Spot] WD | HFW |Det/Mag 20.0 KV} 3.0 |10.06 mm/0.51 mm HV {Spot HFW_ |Det|Mag| —100 um——. 20.0 kV} 3.5 |9.94 mm|0.51 mm| Lfd |500x} HV {Spot} WD | HFW |Det/Mag| pot] | 20.0 KV} 3.0 |10.09 mm|0.51 mm|Lfd |500x! HFW Vv {| WD |Sig|Spot| Mag | 4.28 mm|20.0 kV}14.58 mm|SE| 4.5 |200x| Figure 7. Left valve early dissoconch microstructure. Aequipecten like structure (A, B) showing early origination of pitted microsculp- ture and (C, D) the modified form seen on specimens assigned herein to the genus Pectinid A showing delayed onset of pitted microsculpture. Specimens shown are (A) Leptopecten biolleyi (CTPA 373-B-89), (B) Argopecten gibbus (CTPA 482-B-15) and (C and D) Pectinid A lineolaris (CTPA 519-B-106-1 and 519-B-106-2). of which were rare. All of these undescribed species ap- pear to be geminate sister species to taxa in the Eastern Pacific (Table 4) and are so far indistinguishable morpho- logically based on the small numbers of specimens avail- able. An additional species, represented by 15 left valves, may be Euvola raveneli but due to the lack of right valve specimens we are considering it Euvola sp. cf. E. rave- neli. No specimens of EF. raveneli were positively iden- tified in the collections. COMMONNESS AND RARITY The tropical American scallops do not fit a typical log series or log normal pattern of relative abundance (Figure 15A) observed for mollusks as a whole (Buzas et al., 1982), but more closely resemble abundance patterns of free-living bryozoans from the same region (Cheetham & Jackson, 2000). Most of the species are common to abun- dant and there are fewer rare species compared to other groups. Five out of the 11 Eastern Pacific species (45%) were found in more than 20% of the samples whereas only 7 of the 21 Caribbean species (33%) occurred as frequently (Figure 15B). Despite the poor statistical fit to a log normal distribution, we can perform the exercise of estimating the effect additional sampling would have for discovering additional species in the two oceans (Buzas et al., 1982). In the eastern Pacific a doubling of sampling effort would be assumed to produce roughly 1 or 2 more species. In the Caribbean this number is a little higher, between 2 and 3. In fact, we know that our collections do not contain 5 species of scallop that are described from the Caribbean and the Gulf of Mexico. Rabinowitz (1981) defined rarity in terms of geograph- ic range and abundance (see also Gaston, 1994). We plot- ted the proportion of localities in which the species occurs 1j, I, Sraniiin i Bl, ACS Figure 8. Shell symmetry. Illustration of the common forms of shell convexity in scallops. Equal to sub-equal convexity (A and B) and unequal to highly unequal convexity (C and D). Specimens shown are (A) Caribachlamys ct. mildredae (jts 11-B-1, height (ht) = 26.44 mm), (B) Pectinid A lineolaris (NMB G 17478, ht = 39.69 mm), (C) Euvola marensis (NMB G 17479, ht = 59.92 mm), and (D) Euvola ziczac (NMB G 17480, ht = 49.05 mm). against the log of abundance for each species in the sam- ples (Figure 16). We then divided the field into 4 quad- rants defined by the median values of the two axes; high abundance and wide range (upper right), low abundance and wide range (upper left), high abundance and small range (lower right), and low abundance and small range (lower left). Abundance and frequency of occurrence are highly positively correlated as has been commonly ob- served for other taxa (Jackson, 1974; Cheetham & Jack- son, 1996). In both oceans, 45% of the species occur in the upper right quadrant of this plot. Four of the five most frequently occurring species are from the Pacific (squares in Figure 16) whereas the four species found at the lowest percentage of localities are all from the Caribbean (circles in Figure 16). In addition, 7 of the 8 previously unde- scribed species (solid points) are in the lower left (fewest localities and lowest abundance) quadrant. The eighth species is relatively abundant but not widespread. DISCUSSION The problems associated with sampling rare species can have a strong effect on taxonomic practice as revealed by the rare species recorded in this study. First, all of the 8 previously undescribed species are virtually identical to previously described species in the other ocean and are likely geminate species (Table 4). Most of these species are rare. Very similar results were observed for gastro- pods of the Strombina group, for which the numbers of apparent geminate species pairs increased substantially with increased sampling (compare Jung, 1989 with Jack- son et al., 1993, 1996). The rarity of one or the other of geminate species pairs likely reflects response to chang- ing environmental conditions since the final separation of the two oceans by the rising Isthmus of Panama. Second, the rarity of apparent geminate species may sometimes result in the failure to record an entire genus or subgenus from one ocean or the other. For example, the discovery of Pseudamusium (Peplum) sp. D cf. P. (P.) fasciculatum (Figure 2M, N) is the first reported occur- rence of this genus or sub-genus in the Caribbean. Third, the rarity of certain taxa may lead taxonomists to mistakenly question the provenance of apparently rogue specimens in old museum collections. For example, Lindapecten sp. B cf. L. acanthodes (Dall, 1925) in the Pacific and Spathochlamys sp. A cf. S. vestalis (Reeve, 1853) may actually have been previously described and later discredited due to lack of additional material. Grau (1959) discussed the species Pecten squarrosus Carpen- ter, 1865. Due to the similarity of the type specimen of P. squarrosus to L. acanthodes in the Caribbean, and the absence of any additional specimens resembling the type specimen in the Eastern Pacific, the name was considered nomen dubium. Grau did take into consideration known problems with Carpenter’s localities. Our point here is not that this name is in fact valid, but that discrediting of the name based solely on the lack of subsequent material is questionable because so many species are rare. The occurrence of the species Spathochlamys sp. A (Figure 2G, H) in the Caribbean is a similar example. Page 36 The Veliger, Vol. 48, No. 1 Figure 9. Euvola, Cryptopecten, and Laevichlamys. (A, B) Euvola sericeus (CTPA 405-B-25, (A) lvh = 43.64 mm, (B) rvh = 42.80 mm), (C) £. sp. E. (CTPA 326-B-52, rvh = 36.01 mm), (D, E) E. ziczac (NMB 17662-B-3, (D) lvh = 47.35 mm, (E) rvh = 49.05 mm), (F) E. cf. raveneli (CTPA 503-B-115, lvh = 12.4 mm), (G) E. chazaliei (CTPA 482-B-4, lvh = 20.05 mm), (H) E. chazaliei (CTPA 329-B-9, rvh = 22.8 mm), (I, J) Cryptopecten phrygium (NMB G 17481, (1) lvh = 31.58 mm, (J) rvh = 23.8 mm), (K, L) Laevichlamys multisquamata (CTPA 579-B-4, (K) lvh = 16.81 mm, (L) rvh = 12.25 mm). J. T. Smith et al., 2005 Page 37 7 " ey ) a am EEN Figure 10. Caribachlamys. (A, B) Caribachlamys cf. mildredae (jts 11-B-1, (A) lvh = 26.5 mm, (B) rvh = 26.58 mm), (C, D) C. imbricata (NMB G 17482, (C) lvh = 35.01 mm, (D) rvh = 34.75 mm), (E) C. sentis (CTPA 525-B-7, lvh = 13.67 mm), (F) C. sentis (CTPA 487-B-89, rvh = 13.66 mm), (G, H) C. ornata (NMB G 17483, (G) lvh = 18.39 mm, (H) rvh = 17.74 mm). Spathochlamys vestalis (Figure 2E, F) was originally de- scribed from the West Indies. Waller (1993) determined this locality to be in error, partially based on the resem- blance of the type specimen to specimens of Chlamys lowei (Hertlein, 1935) from the Gulf of California. Again, Waller did take into account known locality errors within Reeve’s collection. However, the discovery of Spathoch- lamys sp. A in the Caribbean may in fact indicate that the original locality data was not in error. This would necessitate the use of the name Spathochlamys vestalis for the Caribbean species, and Spathochlamys lowei for the eastern Pacific species. We are not advocating this nomenclatural change in this paper, only again emphasiz- ing the dangers associated with making assumptions re- garding geographic distributions based on faunas that have not been sampled sufficiently. A final similar example concerns Caribachlamys ct. mildredae (Figure 10A, B) that was recently collected by The Veliger, Vol. 48, No. 1 ge 38 ) Pa O€T CC ee al LOI/0V ae ri/p rast COM/PO S/T 1/6 a O+r/6 i> OIPl/r8 — Se/Ol EL9/TS Es ICI/LC C/T CT i? 8/S a 6r/rc = OOL/8 1¢/6 as 9/P a 6Lt/c9_ = ST/6 cl/9 = OL/el Tad ECOL/OS aa C9/OE t/C le/cl I/I OP/LI Ls Ic/Ol ig 1/1 ae ec/S ae OLT/Te Pre cST/ES = OT/S CSL/V9~—s LI /OI C1/8 I/I Lc/ol T/T ee/LI I/T Lit = TTe/Ss 6/V C8TI/8S See cOr/9r = OS/ST [RIOL das 1/1 r6/01 t/C 897/81 rl/9 9Cr/TI I/1 W9 Ok 9] LI cl C/I as Ov/8 08/P S/T 4 Isc/91 9OT/L 61/8 Lit I/I C/I 81/8 ct/e 1/1 6/€ 9/S L/S P/E as I/T C/I SOT/ol S/v 8v/9 8S/C = v/T 8/S P/t O/€ UC 08/8 OL/S 6/c v/t OT Vd L1/C 1Ol/r1 C/T 88c/61 6v/9 C/T S/t C/I SC/8 vel/rl 6/v LIV 8/S Ld el S9/O1 SI/S LI/8 CT I/T CI/S ISc/Ol NWO O¢/r1 L/S 19/11 I/I e/T c/e 6/L 98/Tl HO'l OTI/ET e/C O8t/1T 961/ST dD (47 II (6°) GRE CG — ys Z — q‘vZ = u ‘WI G SE/L ES = qv 9g L8t/8T it ¢] = wT ¢] = 1 €1 a) o¢ = qve 1€/6 ape €/T POT = qv il Z1/9 JOE] = PO €] EPTI/6T 390 PET = y ‘3 €] — 116 = 2‘P 6 == yd ZI aa 26 TIP q‘t 6 Co/rl JOTI — PO ZI aE YS 6 — J6 = J 01 — POO! LIE d‘oZ = 147 L8OI/EE 49.9 — pig OD omn3ty SOTBIO'T [LIOL, ssouyory [eIOL (EGR ‘OADDY) SVIsaa sKwpjYyooysods vy ds sdiupjyooyjods (L681 “Usng pur [[49A.) yoipauag sdupjyooyjnds qd ‘ds (wnjdag) wnisnuppnasg (SPS ‘Spuly) waypynoiosv{ (wnjdag) wnisnuppnasg (6181 ‘Yolwureyq]) szpjoaul] Wy plundad (OPQ ‘AUBIGIO .p) SIsuazaquin] Uajadiovg (OZ6Il ‘Wed) 11] Uajoadiovg (TSB ‘aAday) snavydoona) uajoadiovg D ‘ds uajsadipon (QGL] ‘snoevuury) snsopou uajsadipon (EGR ‘AADDY) SNIMYJAD UaJIadIpoN gq ‘ds uajoadppurT (SZT6I ‘ed) Sapoyluvon uajoadppurT (SEG “Ula[IAH) O4a]aA UajoadojdaT 9 ‘ds uajoadojdaT (Qp6[ ‘SUONS pure ulap4aH) 14a7/01g uajoadojdaT (ZS8I ‘aAday) DAD UajoadojdaT (POST ayund) vivwonbsyjnu skwupjyoaavT (QCLI “SnevuUuly) 992912 DjJOANT 4 ds pjoang q ‘ds vjoang (CPR “Spulp{) SNad1as DJOANT (196 ‘UOSS|O) SNjnsad YjoAn| (16L] ‘uljouID) Wuasnp) vjoangy (QO6I ‘Sloquozjneqd) Ja1jpzZpYI DJoOAN| (R681 ‘Wed) wyauaavs [9 pjoang (€CQ] ‘AADIY) SUas sAup]YyovgLUvy (T6LI ‘UljouUID) vIvIIIqQui sXuD]YOVGUvD H ‘ds sdwppyoajovig (ESQ ‘ZNpOOY) wnsD]YUY SAUDIYIAJIVAG (TH8l ‘TE Aqiamos) snsoo1guada uajoadosiy (QCL] ‘snoeuurq) snqgqis uajoadosuy PXUL ‘vuuvurg ‘seg ues (gS) pure ‘vureULg ‘sao}INnbsoypy JO JIND (INO) ‘eureurg ‘uoose’T mbryD (D7) ‘eweurg ‘Avg sueIWwyy (vq) ‘veuleurg ‘O10], Joep seoog (Lq) ‘enSeiesin ‘skeD oynbsop (NINO) ‘seinpuoy ‘sheg sourys0D (HOT) ‘eweurg ‘eueurdg JO J[NH (qH) “vurvuedg ‘mbiuyD Jo FIND (QO) ee pao suowey seded sty) ur usurrsads ay) SunensnyE Joquinu oinSy oy} 0} siajor (OINSIY) UUINJOD puodsas sy], “sudUtIoads Jo JoquINU/sONnTTRoo] Jo Joquinu sev payiodar ore saouatmM990 ay, “Apnys sty) ul posn pure sojdwies vq LO ou) Woy poayiodas satoads [Te Jo saoua1iM99Q PaCLAD J. T. Smith et al., 2005 Page 39 Table 3 Measures of Diversity. Values are given for all 9 regions sampled in this study and combined as oceans for com- parison. Richness is the number of species, H is the Shan- non-Weiner Index, and a is Fisher’s Alpha. H and « are calculated as described in the text. Rich- Region ness H Qa All Caribbean Samples 22 2.1188 3.0477 Cochinos Cays, Honduras 17 2.0679 3.9760 Mosquito Cays, Nicaragua 15 1.4470 3.0575 Almirante Bay, Panama 1S 1.9501 3.0989 Bocas del Toro, Panama 21 2.0257 3.8361 Chiriqui Lagoon, Panama 17 1.7113 3.0812 Gulf of Mosquitoes, Panama 16 1.5847 2.6138 San Blas, Panama 14 2.1150 3.3667 All Eastern Pacific Samples 11 1.4103 1.3840 Gulf of Chiriqui, Panama 11 1.3788 1.4340 Gulf of Panama, Panama 8 1.4303 1.2242 snorkeling in 2 meters water depth from the Bocas del Toro region of Panama, and therefore not included in analyses of the dredge samples. Numerous other speci- mens were observed living attached to branching corals Table 4 Geminate species pairs. We are considering 9 groups of species to be geminate species pairs. All but 1 of these pairs includes a previously undescribed species. Unde- scribed species are indicated using open nomenclature as discussed in the text. Pacific geminate Caribbean geminate Bractechlamys antillarum Euvola sp. E Euvola sp. F Leptopecten bavayi Bractechlamys sp. H Euvola sericeus Euvola perulus Leptopecten velero Leptopecten biolleyi Lindapecten sp. B Nodipecten arthriticus Leptopecten sp. C Lindapecten acanthodes Nodipecten sp. G Pseudamusium (Peplum) Pseudamusium (Peplum) sp. D fasciculatum Spathochlamys vestalis Spathochlamys sp. A and additional specimens have been identified from pri- vate collections in the region (Kim Hutsell, personal com- munication, 2001). Olsson and McGinty (1958) reported the species C. mildredae from Bocas del Toro, well out- side its previously reported geographic range. Cahill (1990) discredited this report based on his inspection of several specimens from the San Blas Archipelago finding Figure 11. Lindapecten. (A) Lindapecten acanthodes (CTPA 334-B-5, lvh = 4.92 mm), (B) L. acanthodes (CTPA 445-B-3, rvh = 13.88 mm), (C) L. sp. B (CTPA 394-B2, lvh = 5.16 mm), (D) L. sp. B (CTPA 399-B-147, lvh = 10.53 mm). Page 40 The Veliger, Vol. 48, No. 1 Figure 12. Euvola. (A, B) Euvola marensis (NMB G 17479, (A) left valve height (lvh) = 59.92 mm, (B) right valve height (rvh) = 57.91 mm), (C, D) E. laurenti (CTPA 494-B-11, (C) lvh = 61.31 mm, (D) rvh = 64.38), (E) E. perulus (CTPA 378-B-77, lvh = 21.33 mm). (F) E. perulus (CTPA 368-B-100, rvh = 28.71 mm), (G, H) E. sp. F (CTPA 534-B-62, (G) lvh = 17.38 mm, (H) rvh = 17.85 mm). that these specimens were variants of Caribachlamys im- bricata (Gmelin, 1791) and specimens of that variant were most likely the basis for Olsson and McGinty’s re- port. However, our discovery indicates that Olsson and McGinty most likely did sample this species although it may not be C. mildredae. It is apparently intermediate between C. imbricata and C. mildredae. Once again, ex- tensive sampling is essential before one ascribes too much taxonomic importance to the absence of specimens from collections. J. T. Smith et al., 2005 Page 41 Figure 13. Leptopecten and Pacipecten. (A, B) Leptopecten biolleyi (CTPA 465-B-169, (A) Ivh = 10.31 mm, (B) rvh = 8.72 mm), (C, D) L. sp. C (CTPA 485-B-111, (C) Ivh = 10.06 mm, (D) rvh mm (F) rvh = 7.33 mm), (G, H) L. bavayi (CTPA 556-B-46, (G) lvh 10.41 mm), (E, F) L. velero (CTPA 407-B-172, (E) lvh = 8.78, = 8.61 mm, (H) rvh = 8.49 mm), (I, J) Pacipecten tumbezensis (CTPA 421-B-67, (I) lvh = 20.62 mm, (J) rvh = 24.83 mm), (K) P. leucophaeus (CTPA 533-B-76, rvh = 7.52 mm), (L) P. linki (CTPA 337-B-49, lvh = 15.14 mm), (M) P. linki (CTPA 538-B-58, rvh = 15.34 mm). CONCLUSIONS The numbers of species of scallops in the southwestern Caribbean is more than double that in the tropical Eastern Pacific. However, the magnitude of differences observed across the Isthmus depends greatly on the frequency and spatial scale of sampling. Numbers of species from in- dividual large samples are similar in the two oceans be- cause the much greater abundance of specimens in the Pacific masks the actual differences in regional diversity. These differences are consistent with the much higher primary production by phytoplankton and greater food availability for suspension feeders in the tropical Eastern Pacific (Birkeland, 1977, 1987; Coates et al., 1996; The Veliger, Vol. 48, No. 1 o o) Page 42 aie ~o wo ene -s o°osm — or) on — emo 0-0 9 7" — COP OS no 5 Wiss = ® = Wy a ee 4 Amie on on, — SR OBA it, —— i, a le es Te) =3 O2% Zz = T T T T ft] 1000 2000 3000 Richness T T RES {PIs f peor | 0 20 40 60 80 100 120 Number of Samples Figure 14. Species richness. Plots of species richness shown as cumulative sampling curves for both number of specimens (up- per plot) and number of samples (lower plot). Diversity is plotted as species richness for the Caribbean (C) and the Eastern Pacific (EP). D’Croz and Robertson, 1997; Jackson & D’Croz, 1998). Numbers of species from the different regions sampled are consistently about one and one half times greater in the Caribbean regions compared to the Eastern Pacific, and even higher at Bocas del Toro. However, many Ca- ribbean species occur in only a fraction of the regions sampled, as compared with the broader distribution of Eastern Pacific species. This is because of the much greater differences in environmental conditions such as Paclfle Fauna wn cH 2 % Qo = o, w= Ff is} = a | eeuie ee rosa) J z Jd 6 a] ig 12 Species Richness Carlbbeanm Fauna Lie] a = Sed so 4 | 3 = & _ Fu 1 2 r £ 5 10 12 A. Species Richness Figure 15. ON 08 4 wo i) v2 = 5 a oD 8 085 ° Ws) o 6 € 04- o ge g 0° 2 ) oO 02-4 ola 5 ° BE Q ° ° > or eta me 6 Salt T T T T T T T 0 10 100 1000 Abundance Figure 16. Abundance vs. geographic range. Pacific species represented by squares and the Caribbean fauna by circles. Pre- viously undescribed species shown as solid points. the relative abundance of well developed coral reefs and sea grass meadows among the Caribbean regions. Thus, the full differences in diversity are only apparent after intensive sampling from all the regions combined, and even this is almost certainly inadequate for collecting all the species present. These effects of sampling scale are summarized in Fig- ure 17, showing the relationship between numbers of spe- cies encountered and the geographic area (numbers of Pacific Fauna Number af species: Proportion of Localities Caribbean Fauna cee Number of species ' i nO 02 O8 B. Proportion of Localities Commonness and abundance of tropical scallops. Upper plots represent the Pacific fauna and the lower plots the Caribbean. (A) Histogram of species richness by locality. (B) Histogram of proportion of localities of occurrence. Proportion is plotted as opposed to absolute numbers of localities to normalize for unequal sampling effort. J. T. Smith et al., 2005 25 A Caribbean 20 B Pacific 15 10 Species Richness Oceans Localities Regions Figure 17. Species area plot. The x-axis represents 3 distinct “geographical”’ values: locality, region, and ocean. The y-axis plots the number of species found. Points do not depict the dis- tribution of values, only the ranges. The lines were plotted as a simple best-fit model using Excel. regions) sampled. The curves describe a general logarith- mic fit to the data from each ocean in the form of sam- pling effort curve. Despite the larger number of regions sampled, the Caribbean curve is still rising steeply in comparison to the Eastern Pacific. In some ways this is analogous to Whitaker’s (1972) measurement of beta di- versity. The alpha (local) diversity is roughly the same in either ocean, which very likely explains the considerable previous confusion about patterns of diversity across the Isthmus. Beta (regional) diversity is more difficult to quantify, but in this analysis it can be crudely approxi- mated as the slope of the line as the geographic range is expanded from locality to region to ocean. This slope is much higher in the Caribbean than in the Eastern Pacific. The gamma (ocean) diversity is clearly higher in the Ca- ribbean, although considerably more sampling is needed in both the Eastern Pacific and southwest Caribbean to more accurately estimate the magnitude of difference across the Isthmus. Acknowledgments. Sampling could not have been completed without the assistance and expertise of the crew of the RV Urraca and the staff of the NAOS Marine Laboratory. Preparation and processing of the dredge samples was accomplished through the efforts of Marcos Alvarez and Felix Rodriquez at CTPA. Jon Todd outlined the initial taxonomic identification protocols used by the PPP. Ken Johnson provided invaluable assistance in anal- yses, fieldwork in the Dominican Republic, and management of the research collection and data. Kim Hutsell provided valuable comment on taxonomic identification and observations of private collections from the region. Peter Roopnarine and an anonymous reviewer provided valuable feedback on an earlier version of the manuscript. We thank the government of the Republic of Panama for the permits allowing such a large-scale sampling program. Fieldwork was funded by two separate Scholarly Studies Grants from the Smithsonian Institution to Jeremy Jackson and Helena Fortunato. Funding for the use of the scanning electron microscope at SIO Page 43 was provided by a student research grant from the Western So- ciety of Malacology. LITERATURE CITED AsBoTT, R. T. & P. A. Morris. 1995. A Field Guide to Shells: Atlantic and Gulf Coasts and the West Indies. Houghton Mifflin: Boston, Massachusetts. 350 pp. ALLMON, W. D., G. ROSENBERG, R. W. 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The Panama land bridge as a sea barrier. Proceedings of the American Philosophical Society 110: 425-433. The Veliger 48(1):46—60 (June 30, 2006) THE VELIGER © CMS, Inc., 2006 Additions and Refinements to Aptian to Santonian (Cretaceous) Turritella (Mollusca: Gastropoda) from the Pacific Slope of North America RICHARD L. SQUIRES Department of Geological Sciences, California State University, Northridge, California 91330-8266, USA AND LOUELLA R. SAUL Invertebrate Paleontology Section, Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, California 90007, USA Abstract. This paper presents the first detailed paleontologic study of pre-Campanian (pre-late Late Cretaceous) Turritella sensu lato from the Pacific slope of North America, mainly from outcrops in California. Seven species, two of which are new, have a cumulative chronologic range of late Aptian to Santonian, an interval of 30 million years that coincides with much of Chron C34, the long-normal interval. One of the new species, Turritella xylina, is only the second known Cenomanian Turritella from the study area, and the other new species, Turritella encina, is the first Santonian Turritella reported from the study area. The previously named species are redescribed and are refined in their stratigraphic distributions. They are: Turritella seriatimgranulata Roemer, 1849, of late Aptian age; Turritella infralineata Gabb, 1864, of late early Albian age; Turritella petersoni Merriam, 1941, Cenomanian to early Turonian age; Turritella hearni Merriam, 1941, of Turonian and probably Coniacian age; and Turritella iota Popenoe, 1937, of late Turonian age. Turritella seriatimgranulata is also known from Albian strata in Sonora, Mexico, New Mexico, and Texas. INTRODUCTION The shallow-marine gastropod Turritella Lamarck, 1799, is common in the uppermost Cretaceous (Campanian and Maastrichtian) through Pleistocene rock record of the Pa- cific slope of North America. Stemming from the work by Marwick (1957b), many workers have subdivided Turritella into other genera and subgenera, and these sub- divisions relied on morphologic characters such as the outer lip trace, ontogeny of the primary spirals, and pro- toconch. Kaim (2004), however, reported that until a thor- ough review of this genus is done, shell characters cannot be of use for taxonomic purposes above the species level. Lacking this review of turritellas, we refer these species described in this present paper to Turritella sensu lato. Turritellas have been well studied and used with much success for biostratigraphic zonation of the Campanian through Pleistocene rock record of the study area (e.g., Grant & Gale, 1931; Loel & Corey, 1932; Merriam, 1941; Weaver, 1943; Givens, 1974; Saul, 1983a, b; Squires, 1987), but the pre-Campanian record of Turritella has received far less study. Reports of pre-Campanian Tur- ritella from this region are based mainly on the works of Gabb (1864), Merriam (1941), and Allison (1955). In the last SO years, however, knowledge of the Pacific slope of North America Cretaceous stratigraphy has increased sig- nificantly, and much more collecting has been done. This present study, which expands on the foundation provided by early workers, is based on collections borrowed from all the major museums having extensive collections of Cretaceous fossils from the Pacific slope of North Amer- ica. We detected 56 lots: 29 at California Academy of Sciences (CAS), 23 at Los Angeles County Natural His- tory Museum, Invertebrate Paleontology (LACMIP), and 4 at University of California Museum of Paleontology, Berkeley (UCMP). These lots were collected mostly from California, and a few were collected from northern Baja California (Figure 1). We found specimens that yielded new morphologic information, and we more fully estab- lish the geologic ranges and geographic/stratigraphic dis- tributions of the five previously named species. In addi- tion, we detected two new species. This study establishes the late Aptian to Santonian record of Turritella from California and the northern part of Baja California, Mex- ico. This interval of geologic time coincides with Chron C34, the long-normal interval (Figure 2). Hereafter, these Turritella will be referred to as the “‘long normal”’ tur- ritellas. The significance of this study is that Turritella can be used for biostratigraphic purposes in working with pre-Campanian rocks. The shallow-marine, warm-water aspect of the studied species of Turritella is generally analogous to the ecology of Recent Turritella. A sampling of the literature shows that most species of Recent Turritella prefer shallow-ma- R. L. Squires & L. R. Saul, 2005 1=Siskiyou Co. 2=East of Redding 3=Ono area 4=Sites area 5=Santa Ana Mtns. 6=Punta China Pacific Figure 1. Index map showing locales mentioned in the text. rine depths between low intertidal and approximately 100 m, even though they have been found in waters as deep as 1500 m (Thorson, 1957; Yonge & Thompson, 1976; Squires, 1984; Saul, 1983a; Allmon, 1988). Recent Tur- ritella prefer relatively warm temperatures between 15 15 110 105 LOWER CRETACEOUS Page 47 and 20°C, although they can live in temperatures between 2 and 24°C (Allmon, 1988). They are, however, specifi- cially more diverse and individually of larger size in the tropics than those found in temperate seas (Merriam, 1941). Most modern-day species are largely sedentary and infaunal/semi-infaunal in relatively soft substrate, but many are also mobile and epifaunal on coarser or harder substrates (Yonge & Thompson, 1976). Some species usually remain immobile for long periods of time, shal- lowly buried in soft, level-bottom substrates, then vol- untarily crawl to more sandy bottoms or bottoms covered with gravel in order to spawn (Bandel, 1976; Yonge & Thompson, 1976; Allmon et al., 1992). Most modern-day species of Turritella appear to be ciliary suspension feed- ers, but some or all might be deposit feeders or grazers at least part of the time (Allmon, 1988; Allmon et al., 1992). They can also be extremely gregarious, with up to approximately 500 individuals per square meter (Merri- am, 1941; Petuch, 1976). Information on the mode of development is known (see Marwick, 1957b, Richter & Thorson, 1975, and Bandel et al., 1997) for only a few living species of Turritella. Pelagic larval phases are rel- atively short for these species and range from two days to three weeks (Allmon, 1988). Figure 3 shows the notational system used here to des- ignate the spiral sculpture. This system, which is based on the work of Marwick (1957a), is explained in the cap- tion for Figure 3. Abbreviations, other than those cited above, that are used for catalog and locality numbers are: CIT, California Institute of Technology, Pasadena; UCLA, University of California, Los Angeles (collections now housed at LAC- MIP); USNM, United States National Museum, Washing- ton, D.C. 100 95, 90 85 UPPER CRETACEOUS 2 ; : ia- | Santo- Albian Cenomanian | Turonian eitowe medion Upper | he (ee ae) FE Se | BS ee] (| COUN re a eee el eee ae) SS iN OLLIE EEL xylina Een] f infralineata a Figure 2. Chronostratigraphic positions of the new and restudied Cretaceous turritellas. Ages of stage boundaries and magnetostratig- raphy data from Gradstein et al. (2004:fig. 19.1). Page 48 Figure 3. Diagram showing notation of spiral ribs of Turritella. Primary ribs are denoted A, B, C, and D; secondary ribs are denoted by r, s, t, and u; and tertiary threads are denoted by rj, r,, etc. Change in relative rib strength shown by exchanging up- per. for lower case letters (i.e., capital letters for strong ribs and lower case for weaker ribs). (Diagram modified from Marwick, 1957a:fig. 1). STRATIGRAPHY The geologic ages and depositional environments of most of the Pacific slope of North America formations and members cited in this paper have been summarized in papers by Saul (1982) and Squires & Saul (2003a, b, 2004a, b). These ages range from late Aptian through Santonian, and the depositional environments are usually shallow marine, with post-mortem displacement of some of the shallow-marine faunas into deeper waters via tur- bidity currents. Stratigraphic information mentioned be- low concerns those rock units not discussed in recent lit- erature. Cretaceous Rocks Near Yreka The holotype of Turritella hearni Merriam, 1941, was reported by Merriam (1941:64) as having been collected **.. from the Turonian at the type locality near Montague and Yreka ...,” both of which are in Siskiyou County, northern California. Montague is approximately 8 km slightly southeast of Yreka. Although Merriam never spe- cifically mentioned whether the type locality is at Mon- tague or Yreka, Anderson (1958:153) reported the local- ity to be in middle Turonian beds on the Hagerdorn Ranch, 6.4 km north of Montague. Museum labels in the box that contains the holotype have two locations cited: one at 6.4 km north of Montagu and one 13 km northeast of Yreka. The label that has the official CAS locality number (61938) is the former location. Matsumoto (1960: 97) indicated the beds 6.4 km north of Montague to be Coniacian in age, based on a few ammonites. Utilizing the outcrop map of Sliter et al. (1984:figs. 1, 2), beds in the area just north of Montague (i.e., the Black Mountain area) plot in the lower Coniacian part of the Hornbrook The Veliger, Vol. 48, No. 1 Formation and are probably part of the Ditch Creek Silt- stone Member. Sliter et al. (1984) based their geologic age on the ammonite Prionocycloceras sp. These same workers, however, reported that just southwest of the Black Mountain area, there are extensive covered inter- vals and small discontinuous outcrops of sandstone and siltstone which cannot be correlated to the exact member of the Hornbrook Formation. The age of the beds at the type locality of T. hearni, therefore, cannot be positively determined, but the age is probably early Coniacian. Turritella hearni is also present in the extension of the Hornbrook Formation in Turonian strata (LACMIP loc. 25272) near Phoenix, Jackson County, southwestern Oregon. For a discussion of the age of the strata in this area, see Squires & Saul (2004b). Lower Part of Tuna Canyon Formation Turritella iota Popenoe, 1937, is reported here for the first time from the lower part of the Tuna Canyon For- mation west of Rustic Canyon in the east-central Santa Monica Mountains, Los Angeles County, southern Cali- fornia. The specimens are from coarse-grained sandstone at LACMIP loc. 26967 in the basal part of the formation. Overlying the basal part is a black-shale unit containing scaphitoid-ammonites (Popenoe, 1973; Almgren, 1973; Colburn, 1973). Alderson (1988), based on ammonites, reported that the black-shale unit is late Turonian to Con- iacian age and that the underlying coarse-grained sand- stone beds (i.e., those containing T. iota) are late Turonian in age and are coeval to the upper Baker Canyon and the lower Holz Shale members of the Ladd Formation in the Santa Ana Mountains, Orange County, southern Califor- nia. Prior to this present paper, Turritella iota had only been found in the lower Holz Shale Member of the Ladd Formation; thus, the presence of 7. iota in the Santa Mon- ica Mountains strengthens the age equivalency of these parts of these two formations. BIOGEOGRAPHIC IMPLICATIONS The earliest known records of Turritella are from the Ear- ly Cretaceous (early Valanginian) of Poland (Schréder, 1995; Kaim, 2004) and the Valanginian of France (d’Orbigny, 1842). The earliest known record of Turri- tella on the Pacific slope of North America is Turritella seriatingranulata Roemer, 1849. It occurs in the Tethyan gastropod- and bivalve-rich fauna (Allison, 1955, 1974) of the upper Aptian Alisitos Formation, northern Baja California, Mexico, and this species is described and il- lustrated in this present report. The arrival of Turritella onto the Pacific slope of North America during the late Aptian coincided with both a global trend of rising sea level (Haq et al., 1987) and with warm and equable sur- face waters (Frakes, 1999). During the Albian through Turonian, warm-water con- ditions existed on the Pacific slope of North America R. L. Squires & L. R. Saul, 2005 (Saul, 1986). Shallow-water Albian strata are not plentiful in the study area, and most of the shallow-water Albian mollusks contained in these strata are from redeposited blocks. During the Albian, 7. seriatimgranulata migrated into New Mexico, Texas, and Sonora, Mexico. Although surface currents were predominantly westward-flowing during the Aptian and Albian in the southern part of North America, there were substantial eastward-flowing surface currents (see Johnson, 1999:figs. 2, 3) that could have transported the larvae of T. seriatimgranulata east- ward from the westward part of Mexico. The Turonian coincided with widespread warm seas that were at their highest sea-level stand of the Cretaceous (Haq et al., 1987; Frakes, 1999), and the Turonian coin- cided with the peak in diversity for Turritella species in the study area, with collectively three species present (Figure 2). Two of these species, T. petersoni and T. hear- ni, had the widest geographic distribution of all the stud- ied species. Relative to the Turonian, the Coniacian to early Cam- panian had a slightly cooler climate (Frakes, 1999), and only a moderately high sea-level stand (Haq et al., 1987). The boundaries of the Tethyan Realm were generally broadest during the Aptian to Turonian and the narrowest during the Coniacian to Maastrichtian (Sohl, 1987). These more restrictive conditions might help explain why there is only a single known species, Turritella encina sp. nov., of limited geographic distribution, known from the study area during the interval represented by the Coniacian and Santonian. The paucity of exposures of shallow-water Coniacian strata in California accounts for the scarcity of Coniacian turritellas. Superorder CAENOGASTROPODA Cox, 1959 Order NEOTAENIOGLOSSA Haller, 1882 Family TURRITELLIDAE Lovén, 1847 Genus Turritella sensu lato Lamarck, 1799 Type species: Turbo terebra Linneaus, 1758, by mono- typy; Recent, western Pacific. Diagnosis: Shell small to large, turreted-conical, many whorled, elongate, slender, sculptured with spiral ribs and/or threads, growth lines curved, aperture round and entire, outer lip thin, sinuous and prosocline at suture, columella smooth and concave, operculum horny and multispiral (after Davies, 1971:309). Discussion: The growth lines, noded ribs, and early whorl sculpture of six of the seven turritellas treated in this paper (i.e., T. seriatimgranulata, T. infralineata, T. petersoni, T. hearni, T. iota, and T. encina) are similar. On the basis of shell characteristics, none of these “long normal” turritellas resembles the most common Campan- ian-Maastrichtian turritella stock of Turritella chicoensis Gabb, 1864. Very early whorls of 7. chicoensis stock ap- pear bicostate (ribs B and C) although the peribasal spiral Page 49 D is present, and the whorls become quadricostate (A, B, C, D) by the eight whorl. Early whorls of seventh turri- tella treated in this paper (i.e., 7. xylina) are unavailable, but adult whorls resemble those of Turritella chaneyi Merriam, 1941, stock. Turritella seriatimgranulata Roemer, 1849 (Figures 4—7) Turritella seriatim-granulata Roemer, 1849:413; 1852:39, pl. 4, figs. 12a, 12b; Gabb, 1869:263; Stanton, 1947: 75-76, pl. 56, figs. 7, 11, 17-24; Almazan-Vazquez, 1990:159, pl. 1, fig. 8; Akers & Akers, 1997:93, fig. 78. Not Turritella seriatim-granulata Roemer. Gabb, 1864:132, pl. 20, fig. 88 (two views: natural size and magnified) = tentatively, Turritella packardi Merriam fide Saul (1983a:102—104). Not Turritella seriatimgranulata Roemer. Stewart, 1927: 348-349, pl. 21, fig. 2 = tentatively, Turritella packardi Merriam fide Saul (1983a:102—104). Not Mesalia seriatim-granulata (Roemer). Shimer & Shrock, 1944:495, pl. 203, figs. 3, 4. Turritella marnochi White, 1879:314, pl. 7, fig. 5b (not 5a). Turritella vibrayeana @ Orbigny. Bése, 1910:145, pl. 30, fig. 10; pl. 31, fig. 6. Turritella macropleura Stainbrook, 1940:712, pl. 33, figs. 17, 20-21. Mesalia (Mesalia) mauryae Allison, 1955:414—415, pl. 41, fig. 3. Turritella (Haustator) aff. T. (H.) seriatimgranulata Roemer. Allison, 1955:415, pl. 41, fig. 5. Diagnosis: Adult whorls generally flat sided, with five nearly equal-strength spiral ribs, closely spaced, noded, and alternating with finer noded ribs; R strongest and ca- rina-like. Interspaces with unnoded threads. Description: Shell medium-large (up to 90 mm, estimat- ed, in height), slender. Pleural angle narrow (15°). Pro- toconch and earliest juvenile whorls unknown. Teleo- conch whorls approximately 15 to 17, flat-sided; poste- riormost part of whorls with slightly rounded profile. Late-juvenile whorls (approximately 1.75 mm diameter) with four (R, A, B, and C) nearly equal and squarish ribs, interspaces deep and smooth and about same width as ribs. Adult whorls (approximately 5 mm diameter and greater) with five (R, A, B, C, and D) spiral ribs, nearly equal in strength (R strongest, projecting and somewhat carina-like), equidistant, noded, and alternating with weaker ribs (also noded); resulting in sculpture pattern R, r, A, s, B, t, C, u, and D. Rib r, occasionally present, approaching R in strength, with nodes on both ribs nearly merging. Nodes variable in strength, weakest on D. Threads on all interspaces, very thin, variable in number (three to six), and unnoded; threads most numerous on interspace between B and C, and C and D. Suture deep. Aperture round, inner lip can have thin callus pad. Base of last whorl with unnoded spiral ribs. Holotype: USNM 103148. Page 50 The Veliger, Vol. 48, No. 1 Explanation of Figures 4 to 9 Figures 4—9. Specimens coated with ammonium chloride. Figures 4—7. Turritella seriatimgranulata Roemer, 1849. Figures 4—5. Hypotype UCMP 156008, UCMP loc. A-9521. Figure 4. Abapertural view, <3.5. Figure 5. Tip of specimen shown in Figure 4, 8.7. Figure 6. Hypotype UCMP 156009, UCMP loc. A-9521, right-lateral view, <4. Figure 7. Hypotype UCMP 156010, from near Arivechi, northern Sonora, Mexico, apertural view, X2.5. Figures 8-9. Turritella infralineata Gabb, 1864, CAS loc. 69104. Figure 8. Neotype CAS 69286, apertural view, X3.4. Figure 9. Hypotype CAS 69287, abapertural view, <3.1. Type locality: Either the Walnut Creek or Comanche Peak formation near Fredericksburg, Gillespie County, south-central Texas (Stanton, 1947:76). Geologic age: Late Aptian to late Albian. Distribution: UPPER APTIAN: Alisitos Formation, ma- rine part of upper member, Punta China region, northern Baja California, Mexico. APTIAN-ALBIAN UNDIF- FERENTIATED: Morita Formation, Cerro las Conchas, near Ariveachi, Sonora, Mexico. UPPER LOWER AL- BIAN: Washita and Fredericksburg Groups, Texas. UP- PER ALBIAN: Pawpaw Formation, Texas; Purgatorie Formation, Mesa Tucumcari, New Mexico. Discussion: This study of 7. seriatimgranulata is based on approximately 1000 specimens from the Alisitos For- mation near Punta China (UCMP loc. A-9521) and two specimens from the Morita Formation near Arivechi. The Alisitos material consists entirely of the tips of speci- mens, and the preservation is very good. Poorly preserved small fragments of Turritella identi- fied as T. seriatimgranulata Roemer in Gabb (1864) and Stewart (1927) from Tuscan Springs, Tehama County, northern California were tentatively regarded by Saul (1983a:102-104) to be Turritella packardi Merriam, 1941, which is of early to possibly middle Campanian age. Shrimer & Shrock (1944) refigured both the natural- size view and the magnified view of Gabb’s (1864:pl. 20, fig. 88) specimen and identified it as Mesalia seriatim- granulata. Mesalia (Mesalia) mauryae Allison, 1955, is known only from one locality in the Alisitos Formation. This locality is where T. seriatimgranulata is also found. Mes- alia (M.) mauryae is known only from tips of specimens, and their sculpture is identical to that of the tips of some specimens (see Figure 5) of 7. seriatimgranulata. For this reason, we believe M. (M.) mauryae to be a synonym of T. seriatimgranulata. Gabb (1869:263) reported specimens of T. seriatim- granulata from the Morita Formation near Arivechi, So- nora, Mexico. Stanton (1947:76, pl. 56, figs. 17, 18, 23, 24) stated that these Mexican specimens appear to be within the form range of 7. seriatimgranulata, and he provided illustrations of two specimens of Gabb’s original lot. R. L. Squires & L. R. Saul, 2005 Comparison of specimens (see Figure 7) of 7. seriatim- granulata from the Morita Formation near Arivechi with those from Punta China confirmed that this species occurs at these two locales. All the Punta China specimens, how- ever, are just the tips of this species. At Arivechi, speci- mens are up to 60 mm in height and are missing their tips. We estimate that complete specimens of 7. seriatim- granulata would be approximately 90 mm in height. Ak- ers & Akers (1997) reported that Texas specimens of this species are up to at least 62 mm in height, and Stanton (1947:75) reported that an average specimen, with the apex restored, would be approximately 70 mm in height. The age range of the formations in Texas containing 7. seriatimgranulata is late early Albian to late Albian, ac- cording to Akers & Akers (1997); the age of the Purga- torie Formation in New Mexico is late early Albian, ac- cording to Cobban & Reeside (1952); and the age of the Morita Formation in northern Mexico is undifferentiated Aptian-Albian, according to Almazan-Vazquez (1990). Turritella infralineata Gabb, 1864 (Figures 8—9) Turritella infralineata Gabb, 1864:131—132, pl. 20, fig. 87; Stewart, 1927:291; Merriam, 1941:65, pl. 1, fig. 13 (re- figure of Gabb, 1864). Turritella cf. T. hearni Merriam. Rodda, 1959:123—124 (un- fig.). Diagnosis: Adult whorls generally flat-sided, with four to five, nearly equal-strength spiral ribs (C strongest and can be slightly carina-like), widely spaced and weakly noded; interspaces bearing numerous threads. Description: Shell medium, slender. Pleural angle narrow (11°). Protoconch and juvenile whorls unknown. Teleo- conch with flat-sided to weakly concave whorls. Early adult whorls (approximately 5 mm diameter) with four (R, A, B, and C) nearly equal ribs, weakly noded, and separated by wide interspaces bearing numerous unnoded threads; C strongest and somewhat carina-like. Adult whorls with five (R, A, B, C, and D) nearly equal ribs, R and C strongest, with C usually somewhat carina-like. Ribs s and u occasionally somewhat prominent on later whorls. Suture impressed. Aperture round. Base of last whorl unknown. Growth line deeply sinused, sigmoidal with antispiral sinus between A and B ribs. Neotype: CAS 69286 (designated herein). Neotype locality: CAS loc. 69104. Geologic age: Late early Albian, Brewericeras hulenense ammonite zone. Distribution: Budden Canyon Formation, Chickabally Mudstone Member, Texas Springs area, Shasta County, northern California. Discussion: This study of Gabb’s species is based on 49 Page 51 specimens, all from the Texas Springs area. Preservation is mostly very poor, but at CAS loc. 69104 some of the specimens show moderately good preservation. According to Stewart (1927:291) and Merriam (1941: 65), the holotype of Turritella infralineata is lost. A neo- type (Figure 8) is chosen here. Gabb (1864:131—132) reported Turritella infralineata from the North Fork of Cottonwood Creek area, Shasta County, northern California and from Orestimba Canyon, Stanislaus County, northern California. His locality de- scription for the Cottonwood Creek locality is stratigraph- ically imprecise because this fork of the creek cuts through the entire Budden Canyon Formation, which ranges in age from Hauterivian to Turonian (see Murphy et al., 1969:pl. 1). The probable stratigraphic position of Gabb’s locality, however, was determined during this pre- sent investigation, based on specimens matching the orig- inal description of 7. infralineata from the general vicin- ity of the North Fork of Cottonwood Creek in the Chick- abally Mudstone Member of the Budden Canyon For- mation at Texas Springs in the Ono area (Figure 1, locale 3). This member is of late early Albian age and correla- tive to the ammonite Brewericeras hulenense zone (see Squires & Saul, 2004b). Texas Springs is approximately 12 km northeast of the North Fork of Cottonwood Creek area. Turritella infralineata occurs at several localities in the Texas Springs area, and a total of 16 specimens were detected. The largest specimen is 35 mm in height, but it is incomplete. Preservation is generally poor, but a few good specimens, including the neotype, are from CAS loc. 69104. We were not able to confirm Gabb’s (1864) report of the occurrence of 7. infralineata from Orestimba Canyon, Stanislaus County, and we were not able to make definite identifications of many of the fossils from this area. The canyon cuts across rocks ranging from Jurassic? and Ear- ly Cretaceous to early Tertiary age, and detailed field studies are needed in this area before any definitive bio- stratigraphic work can be done. Turritella infralineata resembles T. hearni, but T. in- fralineata differs by having much weaker nodes and much wider interspaces. Turritella xylina Squires & Saul, sp. nov. (Figures 10—12) Turritella cf. T. robertiana (Anderson). Rodda, 1959:124; Murphy & Rodda, 1960:text-fig. 2. Diagnosis: Adult whorls with concave middle part flanked by shoulder and abapical angulations. Sculpture generally subdued, consisting only of numerous spiral threads. Description: Shell medium (estimated 40 mm total height). Protoconch and early juvenile whorls unknown. Pleural angle 18°. Early adult whorls (approximately 4.5 Pasers2 The Veliger, Vol. 48, No. 1 Explanation of Figures 10 to 17 Specimens coated with ammonium chloride. Figures 10-12. Turritella xylina Squires & Saul, sp. nov. Figure 10. Holotype CAS 69111.02, CAS loc. 69111, right-lateral view, 2.9. Figure 11. Paratype LACMIP 13315, LACMIP loc. 27242, abapertural view, 2.5. Figure 12. Paratype LACMIP 13316, LACMIP loc. 23470, apertural view, <4. Figures 13-17. Turritella petersoni Merriam, 1941. Figure 13. Holotype CAS 1291.06, CAS loc. 1291, left-lateral view, 6.1 Figure 14. Hypotype CAS 69106.02, CAS loc. 69106, apertural view of tip, *8.8. Figure 15. Hypotype CAS 69107.05, CAS loc. 69107, apertural view, X2.2. Figure 16. Hypotype CAS 69284, CAS loc. 2335, abapertural view, 3.9. Figure 17. Hypotype CAS 69285, CAS loc. 69098, right-lateral view, <2.5. to 5 mm diameter) slightly convex, covered by spiral threads of generally uniform strength. Adult whorls (ap- proximately 5 mm diameter and greater) concave between very broad and flattened shoulder area and broad to mod- erately sharp abapical angulation (rib C?); medial part of concave part of whorl commonly bears moderately prom- inent rib B? and several threads. Suture impressed. Growth line sigmoidal, antispiral on concave part of whorl. R. L. Squires & L. R. Saul, 2005 Dimensions of holotype: 24 mm in height, 9 mm greatest diameter (specimen incomplete). Holotype: CAS 69111.02. Type locality: CAS 69111, 122°33'30"W longitude, 40°27'15"N latitude. Paratypes: LACMIP 13315 and 13316. Geologic age: Cenomanian. Distribution: Budden Canyon Formation, Bald Hills Member, North Fork Cottonwood Creek, Shasta County, northern California. Discussion: This new species is based on 38 specimens, and preservation is only moderately good. The largest specimen is 34 mm in height and 13.5 mm in greatest diameter, but the specimen is incomplete. Turritella xylina is unlike the other species described in this present paper. It most closely resembles Turritella chaneyi orienda Saul (1983a:84—-86, pl. 5, figs. 4-11, 16— 17) from upper Maastrichtian strata in central and south- ern California. Turritella xylina differs by having a wider pleural angle, overall weaker ribbing (especially on the concave middle part of the whorls), shoulder closer to suture with narrow interwhorl valley, and whorls sides more vertical with stronger shoulder offset, producing a slightly stepped-whorl appearance. Rodda (1959) identified the new species as Turritella cf. T. robertiana (Anderson, 1958). Anderson (1958) had originally referred his species to Nerinea robertiana, but, as mentioned in Saul & Squires (1998:465), Anderson’s specimens are not nerineids. Saul (1983a) mentioned that T. robertiana is similar to T. chaneyi orienda. She also mentioned that T. robertiana is similar to T. chaneyi Mer- riam, 1941, and tentatively included Anderson’s supposed nerineid in synonymy with 7. chaneyi. Etymology: The species is named for its occurrence in the North Fork Cottonwood Creek area; Greek, xylinos meaning of wood. Turritella petersoni Merriam, 1941 (Figures 13-17) Turritella petersoni Merriam, 1941:64—65, pl. 1, figs. 10, ile Diagnosis: Adult whorls slightly convex to flattish with ribs thin, numerous, weakly noded, closely spaced, and alternating in strength. Description: Medium shell. Pleural angle approximately 18°. Protoconch unknown. Early juvenile whorls (approx- imately 1 mm diameter) convex and bearing ribs r, A, B, and C; interspaces as wide as ribs. Juvenile whorls (1 to 4 mm diameter) convex and bearing ribs r, A, s, B, t, C, u, and d; r approaching strength of A, B, and C on whorls approximately 3 mm diameter); A, B, and C weakly nod- Page 53 ed. Adult whorls (approximately greater than 5 mm di- ameter) slightly convex to flattish (occasionally with slightly tabulate shoulder) and with numerous, thin, very closely spaced, weakly noded ribs, and alternating in strength with weaker ribs. Occasional specimens (see Fig- ure 17) with R, s, A, Bc, u, and d distinguishable, but notation of spiral ribs usually difficult. Threads most common on anterior part of whorls. Some specimens with numerous cycles of single strong rib alternating with bands containing one to four weaker ribs; stronger ribs usually with nodes, weaker ribs unnoded. Suture at but not overlapping d. Area baseward of d with 2 to 3 fine, faintly beaded riblets; bordered by a stronger rib; fol- lowed by weak to stronger alternations of diminishing strength to whorl center. Growth line sigmoidal, maxi- mum of antisinus near midpoint of whorl. Aperture round. Holotype: CAS 1291.06. Type locality: “‘1 mile east of Peterson’s ranch house, 4 miles north of Sites, Colusa County, California’ (Merri- am, 1941:64). Geologic age: Cenomanian to early Turonian. Distribution: CENOMANIAN: Great Valley Group, Sites area, Colusa County, northern California; Budden Canyon Formation, Bald Hills Member, Ono area, Shasta County, northern California. CENOMANIAN OR TU- RONIAN: Valle Group, Cedros Island, Baja California, Mexico. LOWER TURONIAN: Budden Canyon Forma- tion, Gas Point Member, lower part, Ono area, Shasta County, northern California. Discussion: This study of Merriam’s species is based on 149 specimens. Preservation is generally good. Many of the specimens are from the Gas Point Member of the Budden Canyon Formation. Turritella petersoni has been a poorly known species prior to this study. Its geologic age was tentatively re- ported as Cenomanian by Saul (1978:38—39) because of inexact knowledge regarding the location of its type lo- cality. Three moderately well preserved specimens of 7. pe- tersoni were detected from LACMIP loc. 15741 in the Valle Group, Cedros Island, Baja California, Mexico. The specimens are float derived from this group, and utilizing the geologic map provided by Kilmer (1984), the speci- mens are from either the upper part of the lower member (i.e., the Cenomanian Vargas Formation) or the lower part of the upper member (1.e., the Turonian Pinos Formation). Turritella petersoni is similar to Turritella iota but T. petersoni differs by having whorls sides that can be weak- ly convex (never concave) and in not having a moderate carina at C. Turritella petersoni also has more numerous and more closely spaced ribs with the nodes usually stronger, and the sculpture can also vary from ribs having Page 54 nodes to ribs without almost any nodes. The latter vari- ation might be due to ecologic factors. The basal sculp- ture differs from 7. iota in having ribs of alternating strength. Turritella hearni Merriam, 1941 (Figures 18—21) Turritella hearni Merriam, 1941:64, pl. 1, figs. 1-9; Saul: 1982:72 (chart). Turritella tolenasensis Merriam, 1941:62, pl. 1, figs. 14, 15; Saul, 1983a:103. Diagnosis: Whorls slightly convex with three prominent and equal-strength spiral ribs (nodes not strong) on ju- venile whorls, increasing to four prominent spiral ribs (nodes strong and elongate) on later whorls (ribs A and B strongest) and numerous unnoded threads on all inter- spaces. Description: Shell medium. Pleural angle 13°. Proto- conch and earliest juvenile whorls unknown. Whorls slightly convex to flattish. Juvenile whorls (less than 4 mm diameter) with ribs A, B, and C equally prominent and unnoded; ribs r and d weak (see Figure 21). Later whorls (greater than 4 mm diameter) show ribs R, A, B, C, t, and d; ribs A and B most prominent and noded; rib C slightly less prominent and with or without nodes. In- terspaces between ribs on later whorls with 3 to 8 threads; later whorls on some specimens (see Figure 20) only with R, A, B, and C, and their interspaces bearing only threads. Rib d just adapical to suture followed by very fine riblets. At suture, riblet with low elongate nodes; remainder of base with very fine, somewhat wavy riblets. Growth lines sigmoidal, maximum of antisinus somewhat posterior of midpoint of whorl. Suture impressed. Aperture round. Holotype: CAS 61938.01. Holotype dimensions: 27.5 mm height, 7 mm greatest diameter, specimen incomplete. Type locality: CAS 61938. Geologic age: Turonian, and probably early Coniacian. Distribution: LOWER TURONIAN: Redding Forma- tion, Bellavista Sandstone Member and Frazier Siltstone Member, Shasta County, northern California; Budden Canyon Formation, Gas Point Member, lower part, Shasta County, northern California. UPPER TURONIAN: Ladd Formation, Baker Canyon Member, Holz-Baker transi- tion, and lower part Holz Shale Member, Santa Ana Mountains, Orange County, southern California. TU- RONIAN UNDIFFERENTIATED: Hornbrook Forma- tion, Jackson County, southern Oregon. PROBABLY LOWER CONIACIAN: Hornbrook Formation, probably the Ditch Creek Siltstone Member, Siskiyou County, northern California. Discussion: This study of Merriam’s species is based on The Veliger, Vol. 48, No. 1 239 specimens. Many of these are from the Hornbrook Formation, where the preservation is generally very good. A considerable number of specimens, however, are from the Redding Formation, east of Redding. Preservation of the Redding material is also generally very good. Saul (1982:fig. 2 on p. 72) plotted the stratigraphic oc- currence of this species in the Ladd Formation. Merriam (1941) reported Turritella tolenasensis Mer- riam (1941:62, pl. 1, figs. 14, 15) from Cenomanian or Turonian strata in northern California. Saul (1983a:103), however, reported that Merriam’s species is probably con- specific with Turritella hearni and that Merriam’s type material of T. tolenasensis is definitely of Turonian and not Cenomanian age. In this present report, we put T. tolenasensis into synonymy with T. hearni. Merriam (1941) reported Turritella tolenasensis subsp. Merriam (1941:62-63, pl. 1, fig. 12) from Tuscan Springs, Tehama County, northern California. Saul (1983a:102—104), however, tentatively put this subspecies into synonymy with Turritella packardi Merriam, 1941, an early to possibly middle Campanian gastropod. Turritella iota Popenoe, 1937 (Figures 22—23) Turritella iota Popenoe, 1937:401, pl. 49, fig. 8; Saul, 1982: 72 (chart). Diagnosis: Adult whorls slightly concave to flattish with C rib strongest, forming narrow and projecting, weakly noded carina; posterior to carina sculpture consisting of three to four, weak spiral ribs alternating with weaker ones. Description: Medium. shell, slender. Pleural angle ap- proximately 16°. Protoconch and earliest juvenile whorls unknown. Teleoconch whorls very shallowly concave to flattish. Suture impressed. Juvenile and early adult whorls (2 to 4.5 mm in diameter) with R, A, s, B, T, and C, with d appearing at approximately 2 mm diameter; R, A, B, and d weak and thin, C forming narrow and projecting carina. Adult whorls (greater than 5 mm diameter) similar to earlier whorls but with nodes on R, A, B, and C. In- terspaces with threads, especially immediately posterior to carina. Carina of adult individuals rounded on slightly convex base. Base with noded rib adjacent to and paral- leling d, another riblet toward mid base, and otherwise with fine striations. Basal ribs weakening toward aperture. Growth line sigmoidal, antisinus at midpoint of whorl and deepest at s. Holotype: LACMIP 4186. Holotype dimensions: 35.5 mm height, 9.6 mm greatest diameter, specimen incomplete. Type locality: LACMIP 8178. Geologic age: Late Turonian. R. L. Squires & L. R. Saul, 2005 Page 55 Explanation of Figures 18 to 27 Specimens coated with ammonium chloride. Figures 18-21. Turritella hearni Merrriam, 1941. Figure 18. Holotype CAS 61938.01, CAS loc. 61938, right-lateral view, <3. Figure 19. Hypotype LACMIP 13317, LACMIP loc. 24251, abapertural view, <4. Figure 20. Hypotype LACMIP 13318, LACMIP loc. 24251, right-lateral view, 4.9. Figure 21. Hypotype CAS 69099.03, CAS loc. 69099, apertural view, 7.4. Figures 22—23. Turritella iota Popenoe, 1937, LACMIP holotype 40673, LACMIP loc. 8178, left-lateral view. Figure 22. 2.2. Figure 23. Tip of specimen shown in Figure 22, 4.4. Figures 24-27. Turritella encina Squires & Saul, sp. nov. Figure 24. Holotype LACMIP 13319, LACMIP loc. 10798, apertural view, X2.9. Figure 25. Paratype LACMIP 13320, LACMIP loc. 10900, apertural view, X2.9. Figures 26-27. Paratype LACMIP 13321, LACMIP loc. 24336, apertural view. Figure 26. * 1.9. Figure 27. Tip of specimen shown in Figure 26, apertural view, <5.6. The Veliger, Vol. 48, No. 1 Page 56 Distribution: LATE TURONIAN: Tuna Canyon Forma- tion, lower part, west of Rustic Canyon, east-central Santa Monica Mountains, Los Angeles County, southern Cali- fornia; Ladd Formation, transition zone between Baker Canyon and Holz Shale members, and also lower Holz Shale, Santa Ana Mountains, Orange County, southern California. Discussion: This study of Popenoe’s species is based on 13 specimens. Most of them are from the lower part of the Tuna Canyon Formation at LACMIP loc. 26967 and show moderately good preservation. This species is uncommon. It differs primarily from T. petersoni in having whorls that are concave, less numer- ous ribs, and a moderate carina at C. In addition, 7. iota has weaker ribs of more uniform strength on the base. Turritella iota differs from T. hearni in having stronger riblets on the base, crossed by strong growth lines that create a pitted surface. Popenoe (1937) indicated that it resembles somewhat a so-called “‘Turritella whiteavesi Anderson & Hanna,” but Anderson (1958:152) noted that he and Hanna had never named a T. whiteavesi. Saul (1982:fig. 2 on p. 72) reported on the occurrence of this species in the Ladd Formation, and she also re- ported that at its type locality, it is found with Turritella hearni. Turritella encina Squires & Saul, sp. nov. (Figures 24—27) Diagnosis: Adult whorls weakly convex, with four nearly equal-strength spiral ribs (B and C strongest), noded, and alternating with weaker ribs. Description: Shell medium, slender. Pleural angle ap- proximately 14°. Whorls weakly convex. Suture im- pressed. Protoconch and earliest juvenile unknown. Ju- venile whorls (approximately less than 4.5 mm diameter) with three, nearly equal-strength equal spiral ribs (A, B, and C), all with weak nodes. Adult whorls (approximately greater than 5 mm in diameter) with four ribs (R, A, B, and C), each strongly noded and alternating with weaker, usually unnoded ribs, resulting in sculpture pattern of R, r, A, s, B, t, C, u, and d (d very weak). Ribs B and C strongest. Rib t with several threads posteriorly and an- teriorly. Interspace between C and u with threads. Growth line sigmoidal, maxiumum of antisinus coincident with position of rib B. Aperture round. Dimensions of holotype: 28.1 mm height, 9.7 greatest diameter 9.7 mm, specimen incomplete. Holotype: LACMIP 13319. Type locality: LACMIP loc. 10798, 122°04'45"W lon- gitude, 40°38’N latitude. Paratypes: LACMIP 13320 and 13321. Geologic age: Santonian. Distribution: SANTONIAN: Redding Formation, Mem- ber V, Old Cow and upper Clover creeks, Shasta County, northern California. Discussion: This new species is based on 134 specimens, and most show good presevation. Turritella encina is most similar to Turritella hearni, but T. encina differs by having ribs (s, t, and u) present, all of which are noded. Turritella hearni usually has only threads in its interspaces. In addition, on 7. encina, ribs B and C are approximately the same strength, rather than having rib B approximately the same strength as rib A. Etymology: The new species is named for its occurrence in Oak Run, east of Redding; Spanish, encina meaning “oak.” Acknowledgments. We are grateful for access to the collections at CAS, LACMIP, and UCMP and for the loans provided by these institutions. Richard Soto (California State University, Northridge) kindly donated specimens of Turritella seriatim- granulata. The manuscript benefited from reviews by Steffen Kiel (Smithsonian Institution, National Museum of Natural His- tory) and Edward Petuch (Florida-Atlantic University). LITERATURE CITED AKERS, R. E. & T. J. AKERS. 1997. Texas Cretaceous Gastropods. Texas Paleontology Series Publications 6. Houston Gem and Mineral Society: 340 pp. ALDERSON, J. M. 1988. New age assignments for the lower part of the Cretaceous Tuna Canyon Formaton, Santa Monica Mountains, California. Geological Society of America Cor- dilleran Section Meeting, Las Vegas, Abstracts with Pro- grams 20(3):139. ALLISON, E. C. 1955. Middle Cretaceous Gastropoda from Punta China, Baja California, Mexico. Journal of Paleontology 29(3):400—432, pls..40—44. ALLISON, E. C. 1974. The type Alisitos Formation (Cretaceous, Aptian-Albian) of Baja California and its bivalve fauna. Pp. 21-59 in G. Gastil & J. Lillegrave (eds.), Geology of Pen- insular California. Pacific Section, AAPG, SEPM, and SEG, Book 37. Los Angeles, California. 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On old Peterson Ranch, 6.4 km NE of Sites, Lodoga Quadrangle (15 mi- nute, 1943), west side of Sacramento Valley, Colusa County, northern Cal- ifornia. Great Valley Group, informal Antelope Shale, just below the Ven- ado Formation. Age: Cenomanian. Collector: Unknown. CAS 2335. Outcrop just beneath rim rock of Lo- gan Ridge, approximately 1.6 km NE of old Peterson Ranch House, 4.8 km NE of Sites, Lodoga Quadrangle (15 minute, 1943), west side of Sacra- mento Valley, Colusa County, north- ern California. CAS 61938. Approximately 6.4 km N of Monta- gue and approximately, 304 m NE of old Hagerdorn Ranch House, Yreka Quadrangle (30 minute, 1939), Sis- kiyou County, northern California. Hornbrook Formation, probably Ditch Creek Member. Age: Probably early Coniacian. Collector: Unknown. CAS 69098. [= LACMIP 23903]. Large gray limestone nodules in gray mudstone on S bank of creek, 582 m and 73 m N of SW corner of section 29, T. 30 N, R. 6 W, Ono Quadrangle (15 mi- nute, 1952), Shasta County, northern California. Budden Canyon Forma- tion, Gas Point Member, lower part. Age: Turonian. Collectors: P. U. Rod- da, August, 1955. CAS 69099. [= LACMIP 23817]. Sandstone bed in mudstone section, third major W- heading tributary of North Fork Cot- tonwood Creek, S of mouth of Huling Creek, 762 m E and 549 m S of SE corner of section 29, T. 30 N, R. 6 W, Ono Quadrangle (15 minute, 1952), Shasta County, northern California. Budden Canyon Formation, Gas R21; Squires é I: R. Saul, 2005 CAS 69104. CAS 69106. CAS 69107. CAS 69111. LACMIP 8178. LACMIP 10798. LACMIP 10900. Point Member, lower part. Age: Early Turonian. Collector: P. U. Rodda, Au- gust, 1956. [= LACMIP 23893]. Texas Springs, Redding Quadrangle (15 minute, 1946) Shasta County, northern Cali- fornia. Budden Canyon Formation, Chickabally Member. Age: Late early Albian. Collector: Unknown. [= LACMIP 23808]. Shale bank, left side of Roaring River, about 1.2 km above the dam at the basal conglom- erates, 914 m N and 1066 m E of SW corner of section 1, T. 29 N, R. 7 W, Ono Quadrangle (15 minute, 1952), Shasta County, northern California. Budden Canyon Formation, Gas Point Member. Age: Early Turonian. Collectors: W. P. Popenoe and W. Findlay, 1933; P. U. Rodda, 1956. [= LACMIP 23937]. On side of small creek, SE 1/4 of section 20, T. 30 N, R. 6 W, Ono Quadrangle (15 minute, 1952), Shasta County, north- ern California. Budden Canyon For- mation, Gas Point Member, lower part. Age: Early Turonian. Collector: P. U. Rodda, August, 1956. North Fork of Cottonwood Creek, Ono Quadrangle (15 minute, 1943), Shasta County, northern California. Budden Canyon Formation, Bald Hills Member. Age: Cenomanian. Collector: P. U. Rodda. [= CIT 984]. On W side of Rose Canyon, 205 m S and 329 m W of NE corner of section 2, T. 6 S, R. 7 W, Santiago Peak Quadrangle (7.5 minute, 1954), Santa Ana Mountains, Orange County, southern California. Ladd Formation, middle part of Holz- Baker transition zone. Age: Late Tu- ronian. Collector: W. P. Popenoe, Oc- tober 15, 1933. Massive sandstones interbedded with conglomerates on S side of high E-W trending ridge, S side of Oak Run Valley, 998 m S54°50’'W from SE corner of section 10, T. 32 N, R. 2 W, Millville Quadrangle (15 minute, 1953), Shasta County, northern Cali- fornia. Redding Formation, Member V. Age: Early Santonian. Collectors: W. P. Popenoe and C. Ahlroth, July 1, 1936. South side of Old Cow Creek, NE %, Page 59 LACMIP 15741. LACMIP 23470. LACMIP 24251. LACMIP 24336. LACMIP 25272. LACMIP 26967. SW 4% of section 20, T. 32 N, R. 1 W, Millville Quadrangle (15 minute, 1953), Shasta County, northern Cali- fornia. Redding Formation, Member V. Age: Santonian. Collector: V. C. Church, April 12, 1937. Float material from about the middle of the island in a downfaulted syncli- nal block, Cedros Island, Baja Cali- fornia, Mexico. Valle Group (member unknown). Age: Cenomanian or Tu- ronian. Collector: EF H. Kilmer. On E side of North Fork of Cotton- wood Creek, section 16, T. 30 N, R. 6 W, Ono Quadrangle (15 minute, 1953), Shasta County, northern Cali- fornia. Budden Canyon Formation, Bald Hills Member. Age: Cenomani- an? Collector: P. U. Rodda, Septem- ber, 1955. Sandstone cropping out along ridge by ranch road, 914 m W and 259 m S of NE corner of section 26, T. 46 N, R. 6 W, 14.5 km NE of Yreka, Yreka Quadrangle (30 minute, 1939), Siskiyou County, northern California. Hornbrook Formation, Osburger Gulch Sandstone Member. Age: Tu- ronian. Collectors: M. A. Murphy, W. P. Popenoe, and T. Susuki, August 30, 1951. Fossiliferous float concretion in silt- stone on N side of Clover Creek Val- ley, 365 m N and 244 m E of SW corner of section 13, T. 32 N, R. 2 W, Millville Quadrangle (15 minute, 1953), Shasta County, northern Cali- fornia. Redding Formation, Member V. Age: Early Santonian. Collector: W. P. Popenoe, August 15, 1954. South side of Cherry Hill about 100m W of first big turn on Cherry Hills Road and approximately 1 km N of Pioneer Road, west boundary of NW % of section 12, R. 1 W, T. 38 S, Medford Quadrangle (15 minute, 1938), near Phoenix, Jackson County, southwestern Oregon. Hornbrook Formation. Age: Turonian. Collector: Takeo Susuki, 1962. Small exposure of coarse-grained, poorly sorted sandstone at bottom of NW-flowing tributary to main fork of Garapito Creek, 450 m S and 2835 m E of NW corner of section 5, T. 1 S, R. 16 W, Topanga Quadrangle (7.5 Page 60 LACMIP 27242. minute, 1952, photorevised, 1981), Santa Monica Mountains, Los Ange- les County, southern California. Tuna Canyon Formation, lower part. Age: Late Turonian. Collector: J. M. Ald- erson, December 31, 1981. East bank of Cottonwood Creek about 0.4 km downstream from mouth of Huling Creek, fossiliferous concretions weathering out from near top of conglomerate of Bald Hills Member and just below beginning of slabby sandstones and mudstones of UCMP A-9521. The Veliger, Vol. 48, No. 1 Gas Point Member, approximately 533 m N and 274 m E of SW corner of section 16, T. 32 N, R. 6 W, Ono Quadrangle (15 minute, 1953), Shasta County, northern California. Budden Canyon Formation, Bald Hills Mem- ber. Age: Cenomanian. Collector: W. P. Popenoe, April, 1954. Punta China, 25 km SE of Ensenada, northern Baja California, Mexico. Al- isitos Formation. Age: Late Aptian. Collector: Probably E. C. Allison, 1960s. Instructions to Authors The Veliger publishes original papers on any aspect of malacology. All authors bear full responsibility for the accuracy and originality of their papers. 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