Gary Rosenberg

Diversity of Atlantic Coastal Plain Mollusks Since the Pliocene

About 70 percent of tropical western Atlantic mollusk species have become extinct since the Pliocene, which has led to perceptions of a corresponding decline in diversity. However, a compilation of gastropod species from Plio-Pleistocene faunas of the United States Atlantic coastal plain and from Recent western Atlantic faunas indicates that regional diversity has not changed since the Pliocene. Gastropod diversity in the Pliocene Pinecrest Beds in Florida approximates that seen today on either coast of Florida. Gastropod diversity is not demonstrably different in the Recent tropical western Atlantic than in the Recent tropical eastern Pacific. High extinction rates must have been balanced by high origination rates.

A New Critical Estimate of Named Species-Level Diversity of the Recent Mollusca*

Abstract: Modern estimates of species-level diversity in the recent Mollusca range from 34,000 to 120,000 described species, with total diversity including undescribed species often cited as 200,000. Most estimates are unverifiable, not being based on reproducible methods. Ultimately the best way to gauge diversity is explicit enumeration: actual listing of known species. Comprehensive lists of species are valued as a basis for systematic revisions and for comparing diversity across taxa, but it is less appreciated that they also provide a means for statistical sampling of biodiversity databases. I assessed the completeness of molluscan species listings in the World Register of Marine Species (WoRMS) by comparing it to a standardized inventory of the species represented in the Malacology collection of the Academy of Natural Sciences of Philadelphia (ANSP). Random samples of names were scored for presence or absence in WoRMS, with standard errors calculated from the binomial distribution. The WoRMS database has about 1,200 duplicate or extraneous listings for mollusk species and is missing about 1,300 (3%). Overall marine molluscan diversity is estimated at 43,600 ± 900 species, where 900 is a 95% confidence interval. The validity of this confidence interval depends on the WoRMS database and the ANSP collection not having correlated weaknesses. Lack of relatively complete species databases prevents similar assessments for terrestrial and freshwater mollusks, but, using less rigorous methods, I estimate that there are 70,000 to 76,000 described species of recent Mollusca. The low end of this estimate, 70,000 species, is similar to the number of recent chordate species, 69,000, so it is possible that the Mollusca are not the second most diverse phylum of animals in terms of recognized recent species. Naming rates for chordate are currently higher than for mollusk, 750 versus 600 species per year, although the Mollusca are regarded as having higher undescribed diversity. The Mollusca have long been considered the most species-rich marine phylum, but the estimate of 43,600 is substantially below the 56,000 species of Arthropoda listed in WoRMS. Globally, the ratio of marine gastropod to marine bivalve species in WoRMS is 4:1, which is higher than in any regional fauna, suggesting that gastropods have smaller geographic ranges on average than bivalves. The main remaining gaps in WoRMS are among opisthobranchs (8% missing) and Indo-Pacific marine mollusks (6%). The most diverse molluscan genus in WoRMS is Turbonilla, with more than 1,000 species listed as accepted.

Totopotensamides, Polyketide-Cyclic Peptide Hybrids from a Mollusk-Associated Bacterium Streptomyces sp

Two new compounds, the peptide-polyketide glycoside totopotensamide A (1) and its aglycone totopotensamide B (2), were isolated from a Streptomyces sp. cultivated from the gastropod mollusk Lienardia totopotens collected in the Philippines. The compounds contain a previously undescribed polyketide component, a novel 2,3-diaminobutyric acid-containing macrolactam, and a new amino acid, 4-chloro-5,7-dihydroxy-6-methylphenylglycine. The application of Marfeys method to phenylglycine derivatives was explored using quantum mechanical calculations and NMR.

Neuroactive diol and acyloin metabolites from cone snail-associated bacteria

The bacterium Gordonia sp. 647W.R.1a.05 was cultivated from the venom duct of the cone snail, Conus circumcisus. The Gordonia sp. organic extract modulated the action potential of mouse dorsal root ganglion neurons. Assay-guided fractionation led to the identification of the new compound circumcin A (1) and 11 known analogs (2-12). Two of these compounds, kurasoin B (7) and soraphinol A (8), were active in a human norepinephrine transporter assay with Ki values of 2575 and 867 nM, respectively. No neuroactivity had previously been reported for compounds in this structural class. Gordonia species have been reproducibly isolated from four different cone snail species, indicating a consistent association between these organisms.

Discovery of chemoautotrophic symbiosis in the giant shipworm Kuphus polythalamia (Bivalvia: Teredinidae) extends wooden-steps theory

Significance Certain marine invertebrates harbor chemosynthetic bacterial symbionts, giving them the remarkable ability to consume inorganic chemicals such as hydrogen sulfide (H2S) rather than organic matter as food. These chemosynthetic animals are found near geochemical (e.g., hydrothermal vents) or biological (e.g., decaying wood or large animal carcasses) sources of H2S on the seafloor. Although many such symbioses have been discovered, little is known about how or where they originated. Here, we demonstrate a new chemosynthetic symbiosis in the giant teredinid bivalve (shipworm) Kuphus polythalamia and show that this symbiosis arose in a wood-eating ancestor via the displacement of ancestral cellulolytic symbionts by sulfur-oxidizing invaders. Here, wood served as an evolutionary stepping stone for a dramatic transition from heterotrophy to chemoautotrophy. The “wooden-steps” hypothesis [Distel DL, et al. (2000) Nature 403:725–726] proposed that large chemosynthetic mussels found at deep-sea hydrothermal vents descend from much smaller species associated with sunken wood and other organic deposits, and that the endosymbionts of these progenitors made use of hydrogen sulfide from biogenic sources (e.g., decaying wood) rather than from vent fluids. Here, we show that wood has served not only as a stepping stone between habitats but also as a bridge between heterotrophic and chemoautotrophic symbiosis for the giant mud-boring bivalve Kuphus polythalamia. This rare and enigmatic species, which achieves the greatest length of any extant bivalve, is the only described member of the wood-boring bivalve family Teredinidae (shipworms) that burrows in marine sediments rather than wood. We show that K. polythalamia harbors sulfur-oxidizing chemoautotrophic (thioautotrophic) bacteria instead of the cellulolytic symbionts that allow other shipworm species to consume wood as food. The characteristics of its symbionts, its phylogenetic position within Teredinidae, the reduction of its digestive system by comparison with other family members, and the loss of morphological features associated with wood digestion indicate that K. polythalamia is a chemoautotrophic bivalve descended from wood-feeding (xylotrophic) ancestors. This is an example in which a chemoautotrophic endosymbiosis arose by displacement of an ancestral heterotrophic symbiosis and a report of pure culture of a thioautotrophic endosymbiont.

A New Species of Lienardia (Gastropoda: Conoidea) from the Philippines and the Spratly Islands

ABSTRACT. A new species of Lienardia (Conoidea: Clathurellidae) is described from the Philippines and Spratly Islands and compared to L. giliberti Souverbie, 1874, with which it has been confused. The species is routinely found in lumun-lumun nets in the southern Philippines, particularly in the Panglao area, in depths of 50 and HO m. Correlations between radular morphology and shell coloration support maintaining Lienardia and Clathurella as distinct genera.

Seven new species of Thala (Gastropoda: Costellariidae) from the Indo-Pacific

ABSTRACT. Seven new species of Thala are described: T. abelai and T. merrilli (type locality Guam, Mariana Islands), T. evelynae and T. suduirauti (Philippines), T. kilburni and T. pallida (Bassas da India Reef, Mozambique Channel) and T. ruggeriae (Tanzania) and their geographic ranges established. Lectotypes are selected for T. exilis (Reeve, 1845), T. roseata (A. Adams, 1855), T. fusus (Souverbie, 1876), and T. ogasawarana Pilsbry, 1904, and T. fusus is synonymized with T. mirifica (Reeve, 1845). The range of T. lillicoi Rosenberg & Salisbury, 2007 is extended to Kwajalein from Hawaii. Live animals of six species are illustrated. Microsculpture of 14 species is illustrated with scanning electron microscopy.

A Boreal Affair: Acirsa borealis (Lyell, 1841) and Opalia borealis (Gould, 1852) (Mollusca: Epitoniidae)

ABSTRACT. The availability and authorship of Scalaria borealis Lyell, 1841 and Scalaria borealis Gould, 1852 have been subject of considerable debate. Both names are shown to be available and the latter, being preoccupied, should be called Opalia wroblewskyi (Mörch, 1875). Scalaria borealis Lyell, 1841 is confirmed as the type species of Acirsa Mörch, 1857; its current name is Acirsa borealis (Lyell, 1841). Lectotypes are designated for both species.

Dentifusus, a new genus of fasciolariid gastropod from the Philippines with a labral tooth

Abstract Dentifusus deynzeri, a new genus and species from the Philippines, is characterized by a cord-generated labral tooth, beaded lirae on the inner side of the outer lip, and a smooth columella. Despite the smooth columella, we assign this taxon to the Latirus group of genera in Fasciolariidae. The tooth evolved independently of that in other fasciolariid genera. Genus et species novae. Dentifusus deynzeri.

New species of Triviidae (Mollusca: Gastropoda) from South Africa, Namibia and the Philippines

Abstract Three new species of triviid gastropods are described. Galeatrivia Cate, 1979 is synonymized with Triviella Jousseaume, 1884. Thirteen species named as Trivia or Galeatrivia are transferred to Triviella. Species novae: Trivellona bealsi (from the Philippines), Triviella immelmani (from South Africa), Trivia marlowi (from Namibia).