Phylogeny and Biogeography of the Atlantic and Eastern Pacific Hypselodoris Stimpson, 1855 (Nudibranchia, Chromodorididae) with the Description of a New Species from the Caribbean Sea
Alvin Alejandrino and Ángel Valdés
A new species, based on two specimens collected from Guana Island, British Virgin Islands is described. The new species agree with the genus Hypselodoris in having a high body profile, a large vestibular gland, and mantle glands. The new species externally differs from other members of the genus in the Atlantic Ocean by having a reddish background body color. In addition, dorsal color patterns such as a broad central white line with lateral extensions and the lack of yellow lines or spots further differentiate this species. Internally, the radular formula of 52 x 41.0.41 and a smaller seminal receptacle offer distinctive features for this species. The phylogenetic relationships of 34 species and subspecies of Hypselodoris from the eastern Pacific and Atlantic are examined using morphological characters. With the exception of the new species, all these species are characterized by having a dark blue background body color. The phylogenetic analysis of the data matrix resulted in eight most-parsimonious trees. The resulting consensus tree shows that eastern Pacific and Atlantic species of Hypselodoris constitute a monophyletic group, which is basally split into two sister clades. One clade contains the eastern Pacific species and most of the Caribbean species, whereas the other clade contains the eastern Atlantic species. The new species is the sister to rest of the Caribbean species, which are also a monophyletic group.
A unique deep water molluscan ecosystem from the northwestern slope of the Great Bahama Bank
Three successive deep water surveys of the northwestern margin of the Great Bahama Bank, in the vicinity of Victory Cay (Bimini chain) were conducted during years 2001, 2002, and 2003 from the Florida Institute of Oceanography (FIO) research vessels “Bellows” and “Suncoaster”. The surveys were conducted using a fixed frame 1.0' x 3.0' Cape Town dredge at depths of 200-600 meters. Eighty-one species of mollusks belonging to 40 families have been collected and identified, many of which are rare or endemic to the Bimini Islands vicinity. Dredged material consisted of two main components: (1) dead and eroded remains and complete shells of shallow water mollusks that resulted from post-mortem transportation down the steep slope of the Bahama Platform and (2) live deep sea mollusks inhabiting a unique slope ecosystem. The dominant species of this relatively unknown ecosystem are: Conus (Lindaconus) lindae (Petuch, 1987), Tugurium caribaeum (Petit, 1856) and a new species of Scaphella cf. gaudiati Bail et Shelton, 2001. A number of factors are found to control the existence of this unique assemblage including but not limited to the distinctive slope topography of the northwestern margin of the Bahama Bank, and a Gulf Stream funneling effect which alters current structure and velocity at this narrowest portion of the Florida Strait causing an asymmetrical water temperature profile from west to east across the Strait of Florida.
Detecting and interpreting morphologic constraint in the fossil record
Laurie C. Anderson1, Audrey Aronowsky2, and Peter D. Roopnarine3
1Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70803, ; 2Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70803; 3Department of Invertebrate Zoology & Geology, California Academy of Sciences, 875 Howard St., San Francisco CA 94103
At all taxonomic levels, from Baupläne to morphospecies, morphologic variation is neither randomly nor evenly distributed. This pattern is the product of adaptation, constraint, and plasticity acting on populations in ecological time and on lineages in evolutionary time. Because lineages can maintain their morphologic identity over millions of years and numerous speciation and extinction events, constraint is critical to macroevolution.
The Corbulidae (Bivalvia) is a morphologically diverse clade containing several morphologically conservative subclades that provide an opportunity to examine the role of constraint in evolutionary history. For the Caryocorbula + (Bothrocorbula + Hexacorbula) clade, all from Caribbean Neogene deposits, each genus is morphologically distinct both in shape and size. In addition, Caryocorbula morphospecies exhibit strong interspecific allometry that persists despite repeated speciation and extinction, as well as the vagaries of geographic and temporal sample coverage. In spite of the conservative morphology within this basal clade, more derived corbulid clades subsequently occupied new areas of morphospace.
Paleontologic data allow morphology to be examined in a geographic by temporal matrix over evolutionary time scales. For extinct taxa, whose diversity far exceeds that of extant members in many molluscan clades, the fossil record is the only source of information on evolutionary patterns. Thus, although it is often not possible to identify causes of morphologic constraint (e.g., pleiotropy vs. stabilizing selection), the fossil record provides the opportunity to examine morphologic response to changing environmental conditions over evolutionary time both within and among species.
Results of the giant pacific octopus census in Puget Sound, 2000-2005
Roland C. Anderson
The Seattle Aquarium
A scuba diving survey was organized on 19 February 2000 by the Seattle Aquarium in Puget Sound (Washington State, USA) to establish a baseline of how many giant Pacific octopuses (Enteroctopus dofleini) there were in the area and to determine if the population was healthy. Information requested from the volunteer divers was location, depth, time, description of dens, and an estimate of size. There were 18 octopuses spotted that day by 114 divers looking at 19 popular dive sites where octopuses had been seen historically. Four octopuses were females guarding eggs. Since then, the census was increased to the three days of the holiday weekend with increased participation and increased octopus sightings. In 2005 210 divers reported seeing 61 octopuses, none in southern Hood Canal. Implications of the results of this census in relation to behavior, life history, and biology of these octopuses, environmental changes, presence of marine preserves and possible harvest limits are discussed.
The Packaging Problem: Bivalve Prey Selection and Prey Entry Techniques of Enteroctopus Dofleini (Cephalopoda: Octopodidae)
Roland C. Anderson1 and Jennifer A. Mather2
1The Seattle Aquarium; 2University of Lethbridge
When an octopus finds a clam its problems with getting at the food inside are not over, as it still has to get between the hard shells. Enteroctopus dofleini offered the mussel Mytilus trossulus and the clams Venerupis philippinarum and Protothaca staminea solved the penetration problem differently for each prey species. They usually pulled apart the shells of Venerupis. Thinner Mytilus shells were equally often broken, chipped at the edges, or pulled apart. The thicker Protothaca shells were chipped or had a hole drilled in them with the radula and the salivary papilla. Tests of clam strength showed Protothaca the strongest in holding their shells together. When Venerupis shells were wired shut, the octopuses resorted to chipping or drilling instead of pulling. Thus these octopuses have four ways of getting into a clam, and used the easiest method possible, resorting to drilling only when other methods were unsuccessful.
Monospecific fossil assemblages: distinguishing between accumulation and aggregation using phylogeny and paleobiology.
Audrey Aronowsky and Laurie C. Anderson
Dense monospecific assemblages are common in certain living and fossil molluscan taxa such as turritellid gastropods, pectinid bivalves, and corbulid bivalves. These occurrences can be attributed to physical or biological factors. Physical factors leading to monospecific accumulations are generally post-mortem and include winnowing, dissolution, and transport. Biological factors leading to monospecific aggregations generally relate to recruitment and development. Detailed field and laboratory examination of the fossils can refute hypotheses related to physical factors, but often are equivocal for hypotheses related to biological factors, particularly for taxa with features suggestive of indirect development. Biological factors are better tested with paleobiology and extant phylogenetic bracketing. Bracketing is particularly useful in clades that vary in their tendency to form monospecific aggregations, such as corbulid bivalves. Living corbulids such as Varicorbula disparilis form large byssally-attached masses, and their close fossil relatives (e.g. Varicorbula caloosae) tend to be found in monospecific aggregations. Other shallow-burrowing corbulids in which the byssus plays a less important role, such as Corbula contracta, are rarely found as aggregations. Once the biological origin for an aggregation has been established, we can begin to address related questions including why it occurs in a particular place and/or time.
Extinction and the life history of unionid bivalves
Freshwater mollusks are disproportionately represented among recent extinctions. In North America, estimates of historical extinctions of freshwater bivalves (Unionidae) range from 21-37 species, or about 10% of the pre-settlement fauna. Many more extinctions are impending. Reasons for this decline are complex and mainly involve anthropogenic habitat destruction and fragmentation. The dependence of unionids on particular species of fish as hosts for parasitic larva development is an unusual example of “habitat” specialization that may contribute to vulnerability and that complicates efforts to define diversity and conservation priorities. Recent studies of host specificity indicate that some morphologically defined unionid species consist of multiple species or at least host races, which are differentiated by their adaptation to sympatric host fish species and populations. Such differentiation is expected to be most pronounced in mussels that utilize geographically fragmented and genetically diverse host populations. In the unionid morphospecies Cyprogenia aberti, for example, mussel populations in different drainages are able to utilize local populations of several species of darters (Etheostoma, Percina) but generally not populations or species from other drainages. Both host specificity and genetic evidence indicate that C. aberti consists of 3-4 species. Reliance on particular host species or populations probably increases extinction risks for unionids because they share vulnerabilities of the host species as well as their own. However, the hypothesis that host abundance, host genetics, or particular aspects of the host-parasite relationship are responsible for unionid declines is generally untested.
Morphological and behavioral defenses in three species of whelks in the genus Nucella
Paul E. Bourdeau
In contrast to the numerous studies that have examined gastropod shell defenses and defensive behaviors in isolation, few studies have examined the relationship between antipredator behaviors and morphological defenses (size and shell shape) that influence prey vulnerability. I examined the relationship between antipredator behavior and morphological defense in three closely related marine gastropods in the genus Nucella. The three species differ in their degree of morphological defense (shell thickness) and susceptibility to a common crab predator Cancer productus. In agreement with other studies, results showed that thinner shelled species where most susceptible to crab predation. In contrast with other studies, the species with the strongest morphological defense did not exhibit the least behavioral avoidance. Instead, the most morphologically defended species also exhibited the strongest behavioral response to crab predator cues. Within a species, small, more vulnerable individuals showed stronger anitpredator behavior than large individuals. Thick- and thin-shelled individuals did not differ in antipredator behavior suggesting no relationship between behavior and shell thickness. Differences in the relationship between defensive traits among and within species suggest that more studies exploring the relationship between morphology and behavior are needed to understand the evolutionary and ecological importance of gastropod responses to predators.
Molecular systematics of problematic unionids
David C. Campbell
Biodiversity and Systematics, 425 Scientific Collections, Department of Biological Sciences, University of Alabama, Box 870345, Tuscaloosa AL 35487-0345, firstname.lastname@example.org
The combination of high ecophenotypic variation, geographic variation, and rarity in many unionid species have contributed to uncertainty about their systematics. Use of DNA sequencing of the ITS1, cox1, 16S, and nadh1 regions reveal that Lasmigona holstonia as currently recognized is a species complex, with Coosa and Caney Fork system populations both distinct from the Tennessee and New populations. Recognition of species in Toxolasma and Elliptio has ranged from extreme splitting to extreme lumping; molecular data support an intermediate level of species diversity. “Obovaria” olivaria appears relatively distinct from other “Obovaria” species, in agreement with Simpson's recognition of a distinct genus for it. Fusconaia species show strong biogeographic patterns in their distribution; relationships within the flava-cerina-askewi complex remain unclear. Frequent genetic differentiation of populations from different river systems suggests that geographically isolated populations of supposedly widespread species deserve close scrutiny.
Molluscan faunas and zoogeography of the Georgia Neogene
Lyle D. Campbell and Sarah C. Campbell
Division of Natural Sciences and Engineering, USC Upstate, 800 University Way, Spartanburg, SC 29303-4999, email@example.com, firstname.lastname@example.org
Western Atlantic Neogene marine deposits were notoriously patchy from New Jersey south to the Florida Keys and around the Gulf to the Florida Panhandle. Major gaps in the Pliocene record occurred between Charleston, South Carolina and Daytona Beach, Florida, and again between Tampa and the Panhandle. Middle Miocene outcrops and spoil were found in Maryland, Aurora, North Carolina, and the Florida Panhandle. Literature documented only three macro-invertebrate species from the Miocene, and about forty from the Pliocene of eastern Georgia. Based on our study of the Kirby collection from Brunswick, Georgia, we can now document more than 90 Charlton molluscan species (Middle Miocene); over 30 Goose Creek Limestone and 100 Raysor Marl species (Lower Pliocene); over 100 Duplin species (Middle Pliocene); three Waccamaw or equivalent species (Upper Pliocene), and over 100 Late Pleistocene species. The Charlton fauna shared numerous species with the Chipola fauna from the Panhandle. Both were fully tropical, based on an abundance of Vasum, Turbinella, and Melongena. Only two molluscan species, one coral and a sand dollar were shared with the time equivalent, but cooler, Maryland Miocene faunas. This argued for faunal interchange between the Gulf and Atlantic through the Suwannee Strait during Middle Miocene time. In contrast, the Georgia Pliocene faunas more strongly correlated with the subtropical Carolinian province. Cyclocardia and Astarte were abundant, and the species richness of Conus and other gastropods reflected patterns of Carolinian diversity, not the rich tropical diversity recorded from southern Floridian strata.
Systematics and phylogenetics of the family Streptacididae (Gastropoda: Heterobranchia) from Devonian through Triassic marine strata
Matthew R. Campbell
Department of Geological Sciences, Indiana University - Bloomington, 1001 E 10th St, Bloomington, IN 47405-1403, email@example.com.
Streptacididae is among the earliest families in the subclass Heterobranchia, an abundant and ubiquitous subclass of fossil and modern Mollusca. In the Paleozoic, the subclass Heterobranchia contains one informal group with two genera and two species in the Early and Middle Devonian, one family with one genus and one species in the Permian, and the family Streptacididae with seven genera and about 85 species from the Middle Devonian to the Triassic and possibly from the Cretaceous. The family Streptacididae is characterized by a heterostrophic protoconch, small size (0.4 to 14 mm), and an elongate shape. Streptacididae survived both the Late Devonian and Permo-Triassic extinctions.
The family Streptacididae is a basal member of the superfamily Pyramidelloidea based on preliminary cladistic analyses. Splitting the genus Donaldina into additional genera is not supported by cladistic analyses. Taxonomic assignments are revised based on protoconch morphology, spiral ornamentation, and other shell characters. Streptacis and Donaldina are considered to be distinct at the genus rather than family rank, and family Streptacididae is assigned to the superfamily Pyramidelloidea. Authors have proposed that the genus Jiangxispira was an evolutionary connection between the family Streptacididae and the Mesozoic superfamily Cylindrobullinoidea, which likely were basal opisthobranchs.
Mysella pedroana, not another host specific bivalve
Shannon M. Carpenter
Mysella pedroana(Dall, 1898) lives commensally on Isocheles pilosus (Holmes, 1900) and Blepharipoda occidentalis Randall, 1839. Specimens attached to Isocheles pilosus were previously thought to belong to an undescribed species, because of their small size at reproductive maturity and have been referred to in the literature as Mysella sp. H. However, once the variability of dentition and internal structure of small Mysella pedroana and Mysella sp. H were compared, it was determined that the two were in fact the same species. The prevalence of Mysella pedroana was higher on B. occidentalis than on I. pilosus. Those on B. occidentalis were also larger in the gill chambers compared to only juveniles found in the gills of I. pilosus. Variability of characters including size at reproductive maturity, and shell morphology indicates that Mysella pedroana is a highly variable species. The identification of this bivalve as Mysella pedroana is perhaps due to the continuing research on the symbiont and host relationship. Reported host specificity for commensal bivalves may be due to the lack of study or experimental observations. This species was previously thought to be host specific however this assumption has been shown to be invalid.
A Rediscription of Facelina stearnsi Cockerell, 1901 (Nudibranchia: Aeolidacea: Facelinidae) with a reassignment of its generic placement
Jamie M. Chan and Terrence M. Gosliner
Department of Invertebrate Zoology and Geology, California Academy of Sciences, 875 Howard Street, San Francisco, California 94103
Facelina stearnsiCockerell, 1901 is known from Santa Cruz (Nelson 1986) to La Jolla, California (Behrens 1991). Several preserved specimens are examined and comparison is made with the original description and other species in the genus Austraeolis Burn, 1962. The coloration, reproductive and radular morphology are described in detail for the first time using SEM, compound microscopy and photographs of the live specimens. Observation of several new morphological and anatomical characters suggest a reassignment of Facelina stearnsi to the genus Austraeolis Burn, 1962.
North American Physidae (Pulmonata: Basommatophora) - a new perspective on reproductive characters
Stephanie A. Clark1 and Ellen E. Strong2
1Department of Biodiversity & Systematics, School of Biological Sciences, University of Alabama, PO Box 870345, Tuscaloosa, AL 35487, U.S.A., ; 2Department of Invertebrate Zoology, Smithsonian Institution, National Museum of Natural History, Washington DC, 20560, USA
The family Physidae Fischer & Crosse 1886 is a group of freshwater hermaphroditic gastropods with a primarily Holarctic distribution. Although it extends into Central and South America, North America represents the center of diversity for the family, where they are ecologically important members of communities particularly in lentic habitats.
The classification of the Physidae is currently unstable. Over the last century, this classification has been based primarily on a combination of shell and male reproductive characters, culminating in George Te's 1980 classification that relied almost exclusively on features of the penial complex. This scheme was further refined by Dwight Taylor in 2003. Like Te, Taylor's classification is based almost entirely on the penial complex.
However, the incorporation of morphological data into physid classification schemes has been accomplished in the absence of precise character definitions, relying instead on vague notions of penial complex groupings and assumptions of polarity of these characteristics. This hinders efforts to test hypotheses of penial complex evolution and assess the hierarchical level at which discrete changes in penial complex characters are informative. Detailed anatomical studies of both the male and female reproductive systems, including serial histological sections, has revealed an array of new characters and allowed the formulation of discrete character/character state definitions. When these characters are mapped on a recently produced phylogeny of North American physids based on two mitochondrial genes (16S, COI), new insight is shed on the evolution of the penial complex across this clade. Implications for the current classification will be discussed.
Partula: the birth and death of species
Bryan Clarke1 and James Murray2
1Institute of Genetics, Queens Medical Centre, Clifton Boulevard, Nottingham NG7 2UH, England; 2Department of Biology, University of Virginia, Gilmer Hall, Charlottesville, VA 22904-4328, USA firstname.lastname@example.org
Partulid land snails have been unusually informative about the mechanisms of speciation, and recently they have become an exemplar of invertebrate conservation. Here we review the evolution and extinction of Partula species, with an emphasis on some unanswered, or partially answered, questions:
1) Where did the Partulids come from?
2) What caused the exceptional flowering of colour and pattern polymorphisms in Eastern Polynesia?
3) What were the modes of speciation, and how did the species diverge?
4) Why were the Partulids of the Society Islands so susceptible to the introduced carnivore Euglandina rosea?
5) How can we save at least some of them?
6) If we cannot save them alive, what else can we do?
We will give some tentative answers.
A Preliminary Study of the Biology of Veronicella sloanei (Cuvier 1817) in Barbados
Nickelia Clarke & H. Angela Fields1
In Barbados, in the first half of the twentieth century, plant damage caused by slugs was deemed to be 'annoying but not economically serious'. However, by 1950 slug populations and slug damage appear to have increased, as records show that in 1951 a search for parasites suitable for the biological control of Veronicella was undertaken. None were found and today slugs, particularly Veronicella sloanei, are still an important pest in gardens and plant nurseries in Barbados. Research into the biology of Veronicella sloanei was carried out in the 1980s, but the results were never published and have since been lost. In the present study ad libitum sampling of animals in the field, and focal animal sampling and scan sampling of slugs held in aquaria were employed to collect data on the activity budget and mating behaviour of V. sloanei. Slugs were examined for the presence of an inflated bursa copulatrix, a condition that, in this study, was used as evidence of prior sexual activity. Egg clutches found in the field and those produced by captive slugs were incubated and the hatchlings were reared in aquaria. Preliminary data reveal that slugs are active, and will feed, throughout the night until just before dawn. Both in the field and in the laboratory, Veronicella sloanei was found to mate in pairs, in triplets or in groups. An inflated bursa copulatrix was most commonly found in animals with a contracted length of greater than 40 mm.
Molecular Insights into Biogeographic Patterns of Speciation in Marine Molluscs
Smithsonian Tropical Research Institute, unit 0948, APO AA 34002, USA email@example.com
Speciation is generally thought to occur as a result of geographic separation that causes a disruption in dispersal and gene flow between populations. It is difficult to imagine effective geographic barriers to dispersal in the ocean, especially for species with planktonic larvae. However many studies of marine animals, such as echinoderms and fishes seem to support such a pattern of allopatric speciation. Published molecular phylogenetic studies of marine molluscs show that patterns of speciation depend on the taxonomic group and on the region of the world in which the phylogeographic patterns are studied. Research from the Indo-Pacific show a pattern of allopatry between sister species and many small areas of regional endemism and cases with more distantly related species occurring in sympatry. Studies along the Pacific coast of the Americas support a situation where many sister species occur in sympatry. Comparisons across datasets show that those species that occur in sympatry are generally separated by smaller genetic distances than those that are allopatric but that divergences also correlate across geographic region. This suggest that the tempo and mode of speciation varies geographically.
Partulids on Tahiti: an interesting distribution among surviving populations
Trevor Coote and Walter Teamotuaitau
Partulid Fieldwork Programme Consortium, B.P.2407, Papeete, Tahiti, French Polynesia; firstname.lastname@example.org
The extinction of numerous species of endemic land snails in French Polynesia due to the introduction of the carnivorous Euglandina rosea is a salutary lesson in panic biological control undertaken without adequate scientific field trials. Less than 20 of the original 70+ species of the family Partulidae survive on maybe a dozen of the original 17 islands which were previously host to partulids. Last year surveys were carried out in over 60 of the valleys of Tahiti. All of the populations found were of the Partula hyalina/clara sister lineage which previously accounted for only 5-10% of the individuals collected in scientific studies before the introduction of E. rosea. No individuals of the Partula otaheitana/affinis complex were found (over 90% of previous collections) in any valleys, yet these species still survive in many montane forest areas (over 1000 m altitude). Partula nodosa, with a previous distribution of just 7 valleys, is most likely extinct in the wild but persists well in captive populations. Partula filosa, Partula producta, and Partula cytherea (all previously with a single valley distribution) are almost certainly extinct, as are Samoana jackieburchi and Samoana burchi. Samoana attenuata, also surviving on Moorea, is very rare but widely distributed.
Persistence of a Native Brackish-Water Hydrobiid Snail Population in Certain Restored Marshes of Southern Suisun Bay, San Francisco Estuary
Cheryl L. Davis and Christopher L. Kitting
Department of Biology, California State University East Bay, Hayward, CA, 94542 USA, email@example.com
We monitored aquatic invertebrates approximately monthly for over three years (since 1999) and then semi-annually in restored and reference brackish marshes in southern Suisun Bay of San Francisco Estuary. Several sites with marsh tidal pools yielded numerous aquatic invertebrates on modified mesh minnow traps, and thriving hydrobiid snails, related to Tryonia imitator, the endangered west coast brackish water snail. Possible identifications are Tryonia sp. or Hydrobia andersoni (described only from fossils up the ancient San Joaquin River).<span style="lang: en-US" d