COCHLIOPIDAE TRYON, 1866 IS A DIVERSE FAMILY OF CAENOGASTROPODS THAT LIVES IN A WIDE VARIETY OF AQUATIC HABITATS PRIMARILY IN THE NEW WORLD (HERSHLER T STUARDO, 1961; VALDOVINOS 2006) BUT ACCORDING TO ANATOMICAL STUDIES AND PHYLOGENETIC ANALYSIS THE MAJORITY OF THEM HAVE BEEN REASSIGNED TO THE GENUS HELEOBIA STIMPSON, 1865 (HERSHLER & THOMPSON 1992; COLLADO ET AL . 2011A; KROLL ET AL . 2012; COLLADO ET AL . 2013; COLLADO ET AL . 2016). HERE WE FORMALLY DESCRIBE A NEW SPECIES OF THE GENUS HELEOBIA FROM SPRING 1 IN THE CARCOTE SALTPAN, CHILEAN ALTIPLANO, BASED ON MOLECULAR AND MORPHOLOGICAL CHARACTERS. SNAILS FROM THIS LOCALITY WERE PREVIOUSLY SHOWN TO BE DISTINCT BASED ON DNA SEQUENCES (COLLADO ET AL . 2013; COLLADO ET AL . 2016).

PSECTRASCELIS IS ONE OF THE MOST SPECIOUS GENUS OF DARKLING BEETLES OF SOUTH AMERICA, COMPRISING 82 SPECIES THAT INHABIT ARID AND SEMIARID ENVIRONMENTS. THE SPECIES ARE DISTRIBUTED MAINLY IN ARGENTINA AND CHILE. IN GENERAL, THE TAXONOMY OF SEVERAL SPECIES IN THIS GROUP HAS BEEN DIFFICULT TO APPROACH. AN EXAMPLE IS PSECTRASCELIS PILOSA SOLIER AND PSECTRASCELIS CONJUGENS FAIRMAIRE, SPECIES MORPHOLOGICALLY SIMILAR WHICH PRESENTS A RATHER POOR ORIGINAL DESCRIPTION AND MISLABELLED. THESE SPECIES ARE DISTRIBUTED SYMPATRICALLY IN COASTAL TERRACES AT THE NORTHERN SIDE OF HUASCO RIVER, NORTHERN CHILE. WE COLLECTED SEVERAL SPECIMENS OF PSECTRASCELIS ON THE SOUTHERN SIDE OF HUASCO RIVER WHICH ARE MORPHOLOGICALLY SIMILAR TO P. PILOSA. MORPHOLOGICAL AND GENETIC ANALYSIS SUPPORT THE DESCRIPTION OF THE SPECIES PSECTRASCELIS AMMOPHILA SP. NOV., WHICH IS MORE CLOSELY RELATED TO PSECTRASCELIS ELONGATA AND PSECTRASCELIS PILIPES SPECULARIS THAN OTHER MORPHOLOGICALLY SIMILAR SPECIES (PSECTRASCELIS PILOSA AND PSECTRASCELIS CONJUGENS). THE IMPORTANCE OF THE HUASCO RIVER AS BARRIER AND THE EVOLUTIONARY CONVERGENCE IS DISCUSSED TO EXPLAIN THE CRYPSIS AND THE PHYLOGENETIC PATTERN FOUND.

THIS STUDY DELVES INTO THE CYTOGENETIC, MOLECULAR, AND ECOLOGICAL ASPECTS OF THE ALSTROEMERIA PULCHRA COMPLEX, EMPHASIZING THE ROLE OF PRIOR MORPHO-COLORIMETRIC ANALYSES IN DIFFERENTIATING THE INFRASPECIFIC TAXA OF A. PULCHRA. THE INTEGRATION OF ADVANCED MORPHO-COLORIMETRIC ANALYSES PROVIDED A QUANTITATIVE BASIS FOR THIS DIFFERENTIATION, SHOWCASING SIGNIFICANT VARIATIONS IN FLOWER MORPHOLOGY AND COLORATION THAT PRECEDE AND COMPLEMENT THE CYTOGENETIC, MOLECULAR, AND ECOLOGICAL FINDINGS PRESENTED HEREIN. CYTOGENETIC STUDIES UNVEILED CHROMOSOMAL DISPARITIES, AND DIFFERENTIATED GENETIC CLUSTERS SUPPORT THE TAXONOMIC SEPARATION OF A. PULCHRA VAR. MAXIMA FROM A. PULCHRA VAR. PULCHRA AND A. PULCHRA SUBSP. LAVANDULACEA. ADDITIONALLY, UPDATED MORPHOMETRIC DESCRIPTIONS, OBSERVATIONS, AND A DIFFERENTIATION KEY FOR THE SUBSPECIES OF A. PULCHRA ARE PROVIDED. THIS INTEGRATIVE APPROACH NOT ONLY DEEPENS THE UNDERSTANDING OF BIODIVERSITY AND ADAPTATION IN ALSTROEMERIA BUT ALSO UNDERSCORES THE SYNERGY BETWEEN VARIOUS SCIENTIFIC DISCIPLINES TO UNRAVEL TAXONOMIC COMPLEXITIES. THE OBTAINED RESULTS POSE NEW QUESTIONS ABOUT THE EVOLUTION AND ADAPTATION IN RELATED ALSTROEMERIA SPECIES, THE METHODOLOGIES UTILIZED CAN SERVE AS A SIGNIFICANT CONTRIBUTION TO FUTURE RESEARCH AND CONSERVATION OF THIS BOTANICAL GENUS WITH ORNAMENTAL AND ECOLOGICAL VALUE.

HELEOBIA IS THE MOST SPECIOUS GENUS IN THE FAMILY COCHLIOPIDAE, IN WHICH MANY SPECIES ARE MORPHOLOGICALLY SIMILAR. HERE WE USED MORPHOLOGICAL, MICROSTRUCTURAL AND PHYLOGENETIC CRITERIA TO INVESTIGATE SPECIES DELIMITATION WITHIN THE HELEOBIA CHIMBAENSIS COMPLEX ON THE ATACAMA DESERT COAST. THE RANGE INCLUDED SUBDIVIDED POPULATIONS OF THE SPECIES, THE SUBSPECIES HELEOBIA CHIMBAENSIS CONICA, AND THE ALLOPATRIC SNAILS FROM LOS PERALES, FIRST RECOGNIZED AS A POPULATION OF H. CHIMBAENSIS AND MORE RECENTLY CONSIDERED A CANDIDATE SPECIES OF THE GROUP. TRADITIONAL SHELL CHARACTERS, MORPHOMETRIC ANALYSIS, OPERCULUM, AND PROTOCONCH WERE EITHER UNINFORMATIVE OR AMBIGUOUS TO SEPARATE TAXA. HOWEVER, THE PHYLOGENETIC ANALYSIS IDENTIFIED H. CHIMBAENSIS, H. CHIMBAENSIS CONICA AND FOUR ADDITIONAL POPULATIONS OF THE SPECIES AS A MONOPHYLETIC GROUP WHILE THE POPULATION FROM LOS PERALES WAS RECOVERED AS A DISTANTLY EVOLUTIONARY SIGNIFICANT UNIT FOR WHICH THE NAME HELEOBIA PERALENSIS SP. NOV. IS PROVIDED HERE. WHILE THE GEOGRAPHIC ISOLATION AND LIMITED DISPERSAL SEEM TO HAVE INFLUENCED THE DIVERSIFICATION AND CURRENT DISTRIBUTION OF H. CHIMBAENSIS IN ATACAMA, THE ORIGIN OF HELEOBIA PERALENSIS SP. NOV. REMAINS UNCLEAR BECAUSE OF UNCERTAIN RELATIONSHIPS. A CONSERVATION STATUS ASSESSMENT ACCORDING TO IUCN CRITERIA AND NATURESERVE METHODOLOGY SUGGESTS THAT BOTH H. CHIMBAENSIS AND HELEOBIA PERALENSIS SP. NOV. FACE A HIGH RISK OF EXTINCTION.

KNOWLEDGE OF THE REPRODUCTIVE ISOLATION MECHANISMS THAT PREVENT GENE FLOW BETWEEN SPECIES IS ESSENTIAL FOR UNDERSTANDING THE PROCESS OF SPECIATION. IN THIS STUDY, I INVESTIGATE THE SPAWNING PERIODS IN FISSURELLA CUMINGI AND F. LATIMARGINATA, TWO CLOSELY RELATED SYMPATRIC SPECIES OF KEYHOLE LIMPETS WITH EXTERNAL FERTILIZATION, AS A POTENTIAL PREZYGOTIC BARRIER BETWEEN THEM. THE REPRODUCTIVE CYCLE WAS ASSESSED IN TWO DISTINCT LOCATIONS IN NORTHERN CHILE USING THE GONADOSOMATIC INDEX (GSI) AND GONADAL HISTOLOGY. SPECIES, LOCALITY, AND SEX WERE DESIGNATED AS PREDICTIVE VARIABLES, WHILE AVERAGE GSI VALUES, AS WELL AS THOSE OF PARTIAL AND TOTAL SPAWNING, WERE CONSIDERED DEPENDENT VARIABLES. BOTH SPECIES EXHIBIT A CONTINUOUS GAMETOGENIC CYCLE THROUGHOUT THE YEAR, CHARACTERIZED BY MULTIPLE SPAWNING EVENTS. A GENERALIZED LINEAR MODEL (GLM) FACTORIAL ANOVA DESIGN REVEALED THAT NEITHER SPECIES, LOCALITY NOR SEX WERE SIGNIFICANT FACTORS WITH RESPECT TO THE GSI AND PARTIAL SPAWNING SCORES. HOWEVER, SEX WAS FOUND TO BE THE ONLY SIGNIFICANT FACTOR RELATED TO TOTAL SPAWNING. NO SIGNIFICANT INTERACTIONS WERE OBSERVED AMONG PREDICTIVE FACTORS. THESE FINDINGS SUGGEST THAT REPRODUCTIVE PERIODS MAY NOT SERVE AS EFFECTIVE BARRIERS TO GAMETE ENCOUNTERS BETWEEN SPECIES. OUR STUDY PROMPTS QUESTIONS ABOUT HOW CLOSELY-RELATED EXTERNALLY-FERTILIZING SPECIES MAINTAIN REPRODUCTIVE ISOLATION.

THE SPECIES THAT INHABIT SYSTEMS HIGHLY AFFECTED BY ANTHROPIC ACTIVITIES USUALLY EXHIBIT THIS EXTERNAL INFLUENCE IN THEIR GENE POOL. IN THIS STUDY, WE INVESTIGATED THE GENETIC PATTERNS OF POPULATIONS OF HELEOBIA ATACAMENSIS, A FRESHWATER MICROGASTROPOD ENDEMIC TO THE ATACAMA SALTPAN, A SYSTEM HISTORICALLY EXPOSED TO ENVIRONMENTAL CHANGES, AND CURRENTLY SUBJECTED TO CONDITIONS ASSOCIATED WITH METALLIC AND NON-METALLIC MINING AND OTHER ANTHROPIC ACTIVITIES. MOLECULAR ANALYSES BASED ON NUCLEAR AND MITOCHONDRIAL SEQUENCES INDICATE THAT THE SALTPAN POPULATIONS ARE HIGHLY FRAGMENTED AND THAT THE GENETIC STRUCTURE IS MAINLY EXPLAINED BY HISTORICAL GEOGRAPHIC ISOLATION, WITH LITTLE INFLUENCE OF CONTEMPORARY FACTORS. THE MICROSATELLITE RESULTS SUGGEST A MODERATE GENETIC DIVERSITY AND SHARP DIFFERENTIATION MEDIATED BY ISOLATION BY DISTANCE. ADDITIONALLY, DESPITE THE HIGH ENVIRONMENTAL HETEROGENEITY DETECTED AND THE MARKED HISTORICAL DYNAMISM OF THE REGION, OUR DATA REVEAL NO SIGNS OF DEMOGRAPHIC INSTABILITY. THE PATTERNS OF CONTEMPORARY GENE FLOW SUGGEST A CHANGE IN THE CURRENT GENETIC STRUCTURE, BASED ON THE GEOGRAPHIC PROXIMITY AND SPECIFIC ENVIRONMENTAL CONDITIONS FOR EACH POPULATION. OUR RESULTS, HIGHLIGHT THE ROLE OF FRAGMENTATION AS A MODULATOR OF GENETIC DIVERSITY, BUT ALSO SUGGEST THAT THE HISTORICAL PERSISTENCE OF ISOLATED POPULATIONS IN NATURALLY DYNAMIC ENVIRONMENTS COULD EXPLAIN THE APPARENT DEMOGRAPHIC STABILITY DETECTED.

THE BIODIVERSITY OF MOLLUSCS IS HIGHLY THREATENED IN MARINE, TERRESTRIAL AND FRESHWATER ECOSYSTEMS WORLDWIDE. THIS RESEARCH AIMED AT STUDYING THE DISTRIBUTION AND CONSERVATION STATUS OF EIGHT POORLY-KNOWN MICRO-SNAILS OF THE GENERA STEPHACHAROPA AND STEPHADISCUS IN CHILE. WE PERFORMED A COMPREHENSIVE REVIEW OF LITERATURE AND DATABASES TO DETERMINE THE OCCURRENCES OF THE SPECIES, WHICH WERE MAPPED ON VECTOR LAYERS CONTAINING PROTECTED AREAS AND HUMAN DEVELOPMENT INFRASTRUCTURE TO FIND POTENTIAL THREATS. CONSERVATION STATUS ASSESSMENT WAS PERFORMED FOLLOWING THE CRITERIA AND TOOLS IMPLEMENTED BY THE INTERNATIONAL UNION FOR THE CONSERVATION OF NATURE (IUCN) RED LIST AND NATURESERVE. WE ALSO CONDUCTED SPECIES DISTRIBUTION MODELS, BASED ON MAXIMUM ENTROPY, TO IDENTIFY AREAS THAT SHOULD BE PRIORITISED FOR CONSERVATION. TWO SPECIES MEET THE CRITERIA FOR IUCN LISTING AS CRITICALLY ENDANGERED (CR), FOUR ENDANGERED (EN), ONE VULNERABLE (VU) AND ONE LEAST CONCERN (LC). THIS CLASSIFICATION IS RATHER COINCIDENT WITH EQUIVALENT CATEGORIES OBTAINED UNDER THE NATURESERVE STANDARD, IN WHICH TWO SPECIES WERE RANKED AS CRITICALLY IMPERILED (N1), FIVE IMPERILED (N2) AND ONE VULNERABLE (N3). WE FOUND THAT STEPHACHAROPA PAPOSENSIS IS THE MOST AT-RISK SPECIES, WITH ONLY ONE OCCURRENCE NOT INCLUDED IN A PROTECTED AREA, FOLLOWED BY STEPHADISCUS STUARDOI, WITH TWO OCCURRENCES, ONE OF THEM WITHIN A PROTECTED AREA. STEPHADISCUS LYRATUS WAS THE SPECIES WITH THE GREATEST GEOGRAPHIC RANGE, ACCOUNTING FOR 17 OCCURRENCES, SEVEN MATCHING A PROTECTED AREA. WE FOUND WIDER POTENTIAL RANGES IN MODELLED SPECIES THAT MAY BE USEFUL FOR PRIORITISING CONSERVATION MEASURES. CONSIDERING DISTRIBUTIONAL DATA, PROTECTED AREAS AND MORE THAN 20 PLAUSIBLE THREATS IDENTIFIED, WE PROPOSE POTENTIAL IN SITU AND EX SITU CONSERVATION ACTIONS TO PROTECT THESE NEGLECTED MICRO-SNAILS.

THE GENUS RADIODISCUS INCLUDES MINUTE TERRESTRIAL SNAILS OCCURRING THROUGHOUT THE AMERICAN CONTINENT. WE ASSESSED THE CONSERVATION STATUS OF EIGHT POORLY KNOWN CHILEAN RADIODISCUS SPECIES USING THE INTERNATIONAL UNION FOR CONSERVATION OF NATURE (IUCN) AND NATURESERVE CATEGORIES AND CRITERIA. UNDER THE IUCN GUIDELINES THE SPECIES WERE ASSESSED USING THE CRITERION B OF GEOGRAPHIC RANGE, WHICH CONSIDERS THE EXTENT OF OCCURRENCE (EOO) AND AREA OF OCCUPANCY (AOO) AS SUBCRITERIA. FOR NATURESERVE WE USED THESE TWO PARAMETERS PLUS THE NUMBER OF OCCURRENCES, ECOLOGICAL VIABILITY, AND THREATS. CONSIDERING SPECIES RARITY AND POSSIBLE SAMPLING BIAS, WE ALSO USED ECOLOGICAL NICHE MODELING TO DETERMINE CLIMATE AND ENVIRONMENTAL TOLERANCES AND PREDICT POTENTIAL SPECIES DISTRIBUTIONS ANALYZING BIOCLIMATIC AND GEOGRAPHICAL LAYERS. RADIODISCUS AUSTRALIS, R. COARCTATUS AND R. QUILLAJICOLA WERE LISTED AS CRITICALLY ENDANGERED BY IUCN AND NATURESERVE STANDARDS; R. COPPINGERI, R. FLAMMULATUS, R. MAGELLANICUS AND R. VILLARRICENSIS AS ENDANGERED BY BOTH METHODS; WHILE R. RIOCHICOENSIS AS ENDANGERED BY IUCN STANDARDS AND VULNERABLE BY NATURESERVE STANDARDS. NICHE MODELING RESULTS INDICATED THAT RADIODISCUS SPECIES RESPOND TO DIFFERENT ENVIRONMENTAL CONDITIONS AND THAT THE PREDICTED DISTRIBUTION AREAS CONTAIN SUITABLE HABITATS BEYOND THE CURRENT RANGES, WHICH MAY BE HELPFUL FOR FUTURE MANAGEMENT PLANS. NATURE-BASED SPORT TOURISM, FORESTRY ACTIVITIES, URBANIZATION, ROADS, POLLUTION, MINING, FOREST FIRES, LIVESTOCK, VOLCANISM, TSUNAMIS, SOIL EROSION AND INTRODUCED SPECIES ARE AMONG THE MAJOR THREATS AFFECTING THESE SNAILS. BASED ON THE LOW NUMBER OF OCCURRENCES AND THE THREATS IDENTIFIED, THE MOST AT-RISK SPECIES ARE R. COARCTATUS AND R. QUILLAJICOLA (ONE RECORD), R. AUSTRALIS (TWO RECORDS) AND R. VILLARRICENSIS (THREE RECORDS); THE LATTER TWO LACKING OCCURRENCES WITHIN PROTECTED AREAS. COMPILING OUR FINDINGS, WE PROPOSE A LIST OF ACTIONS TO PRESERVE CHILEAN RADIODISCUS SPECIES.

ECOSYSTEMS PROVIDE BENEFITS TO HUMANS, INCLUDING PROVISIONING, REGULATING, AND CULTURAL SERVICES. HOWEVER, INVASIVE SPECIES CAN THREATEN ECOSYSTEM WELL-FUNCTIONING AND SERVICES PROVIDED. ONE INVASIVE SPECIES WITH SUCH POTENTIAL IS THE NEW ZEALAND MUD SNAIL (NZMS) POTAMOPYRGUS ANTIPODARUM. THE AIMS OF THIS STUDY ARE FOCUSED ON THE QUANTITATIVE REVIEW OF (1) THE NZMS IMPACTS ON ECOSYSTEM PROPERTIES AND THEIR DIRECT LINKS WITH ECOSYSTEM SERVICES, AND (2) THE ECOSYSTEM SERVICES THAT CAN BE AFFECTED BY THE NZMS. THE HIGH DENSITY REACHED BY THIS SPECIES IN MOST OF THE INVADED ECOSYSTEMS AND ITS HIGHLY COMPETITIVE ABILITY AFFECT ECOSYSTEM STRUCTURE AND FUNCTIONING. HOWEVER, SOME FACILITATION PROCESSES ON NATIVE SPECIES MAY RESULT IN AN IMPROVEMENT OF SOME SERVICES. THE NZMS TENDS TO POSITIVELY AFFECT CULTURAL SERVICES (88% POSITIVE CASES) BUT NEGATIVELY TO PROVISIONING SERVICES (77% OF CASES). REGARDING, REGULATING AND MAINTENANCE SERVICES, THE PROPORTIONS OF POSITIVE AND NEGATIVE EFFECTS WERE SIMILAR (45% VS 36%, RESPECTIVELY). THEREFORE, THE NZMS IS A SPECIES WITH NUMEROUS NEGATIVE IMPACTS ON ECOSYSTEM SERVICES. HOWEVER, ECOSYSTEM SERVICES RELATED TO HEALTH (E.G., DILUTION EFFECT AGAINST PARASITES) AND RESEARCH (E.G., BIOMONITORING) ARE CULTURAL SERVICES THAT THE NZMS CAN IMPROVE. NO ECONOMIC ASSESSMENT OF THE IMPACTS OF THE NZMS IS AVAILABLE IN THE LITERATURE.

THE INVASIVE NEW ZEALAND MUDSNAIL, POTAMOPYRGUS ANTIPODARUM (GRAY, 1843), WAS IDENTIFY IN CHILE IN 2014 CONSTITUTING, IN TURN, THE FIRST RECORD PERFORMED IN SOUTH AMERICA. UNTIL NOW P. ANTIPODARUM WAS KNOWN BY HAVING TWO VIABLE POPULATIONS IN THE CHOAPA RIVER BASIN, COQUIMBO REGION, NORTHERN CHILE AND TWO IN THE MAIPO RIVER BASIN, METROPOLITANA REGION, CENTRAL CHILE. IN THE SUMMER OF 2016 WE SURVEYED SEVEN WATER BODIES IN THE VALPARAISO REGION, A RELATIVELY LARGE GEOGRAPHIC AREA LOCATED BETWEEN BOTH REGIONS, TO ASSESS THE OCCURRENCE OF THE SPECIES IN CENTRAL CHILE. BASED ON MORPHOLOGICAL ANALYSES AND REPRODUCTIVE FEATURES, WE IDENTIFY THE PRESENCE OF P. ANTIPODARUM IN TWO NEW LOCALITIES. THUS THE DISTRIBUTION OF THIS HIGHLY INVASIVE SNAIL IN CHILE IS EXTENDED TO A MUCH WIDER AREA THAN PREVIOUSLY KNOWN.

SOME NAIDID OLIGOCHAETES ESTABLISH COMMENSAL RELATIONSHIPS WITH SPECIES OF MOLLUSCS WORLDWIDE. IN THE PRESENT STUDY, WE REPORT THE FINDING OF CHAETOGASTER LIMNAEI IN ILLAPEL RIVER, NORTHERN CHILE. THIS WORM WAS FOUND INHABITING THE MANTLE CAVITY OF THE FRESHWATER GASTROPOD PHYSA ACUTA, AN INVASIVE SPECIES IN THIS COUNTRY. THE TAXONOMIC STATUS OF C. LIMNAEI WAS CONFIRMED BY MOLECULAR ANALYSIS BASED ON MITOCHONDRIAL 16S RIBOSOMAL RNA GENE. RESUMEN LOS OLIGOQUETOS NAIDIDAE PUEDEN ESTABLECER RELACIONES COMENSALES CON ESPECIES DE MOLUSCOS ALREDEDOR DEL MUNDO. EN EL PRESENTE ESTUDIO SE INFORMA EL HALLAZGO DEL OLIGOQUETO CHAETOGASTER LIMNAEI EN EL RÍO ILLAPEL, NORTE DE CHILE. LOS ANIMALES SE ENCONTRARON HABITANDO LA CAVIDAD DEL MANTO DEL GASTERÓPODO DE AGUA DULCE PHYSA ACUTA, UNA ESPECIE INVASORA EN ESTE PAÍS. EL ESTADO TAXONÓMICO DE C. LIMNAEI SE CONFIRMÓ MEDIANTE EL ANÁLISIS MOLECULAR BASADO EN SECUENCIAS DE ADN DEL GEN MITOCONDRIAL DEL ARN RIBOSOMAL 16S.

EVAPORITIC ECOSYSTEMS OF THE ATACAMA DESERT CONTAIN A RICH ENDEMIC FAUNA, INCLUDING MOLLUSK SPECIES. A RECENT STUDY PERFORMED IN THE FRESHWATER SNAIL HELEOBIA ATACAMENSIS, ENDEMIC TO THE ATACAMA SALTPAN, REVEALED A STRONG INTERDEPENDENCE OF GENETIC PATTERNS WITH CLIMATIC FLUCTUATIONS AND LANDSCAPE PHYSIOGRAPHY. THE SPECIES IS CURRENTLY LISTED AS CRITICALLY ENDANGERED AT REGIONAL SCALE AND AS DATA DEFICIENT ON THE INTERNATIONAL UNION FOR CONSERVATION OF NATURE (IUCN) RED LIST. HERE, WE STUDIED GENETIC DIVERSITY AND DEMOGRAPHIC HISTORY OF SEVERAL POPULATIONS OF THE SPECIES OCCURRING ON A CONNECTIVITY GRADIENT, INCLUDING SNAILS FROM NEW PERIPHERICAL LOCALITIES (PEINE AND TILOMONTE), WHICH WERE COMPARED WITH TOPOTYPE SPECIMENS. IN ADDITION, WE REASSESSED THE CONSERVATION STATUS USING THE IUCN RED LIST CATEGORIES AND CRITERIA CONSIDERING SPECIES-SPECIFIC IDIOSYNCRASY. PHYLOGENETIC AND PHYLOGEOGRAPHICAL ANALYSES INDICATED THAT SNAILS FROM PEINE AND TILOMONTE BELONG TO H. ATACAMENSIS. WE DISCOVERED SIGNIFICANT DIFFERENTIATION IN SHELL MORPHOLOGY, WHICH WAS GENERALLY GREATER IN GEOGRAPHICALLY ISOLATED POPULATIONS. WE ALSO INFERRED SIX GENETIC CLUSTERS AND A DEMOGRAPHIC EXPANSION CONGRUENT WITH THE WET PERIODS THAT OCCURRED AT THE END OF THE PLEISTOCENE. CONSIDERING THE HIGHEST RISK CATEGORY OBTAINED, H. ATACAMENSIS WAS REASSESSED AS ENDANGERED AT REGIONAL SCALE. FUTURE CONSERVATION PLANS SHOULD CONSIDER THE GENETIC ASSEMBLAGES AS CONSERVATION UNITS.

THE ISOLATED WATERSHEDS OF THE SOUTHWESTERN ANDEAN ALTIPLANO CONSTITUTE A NATURAL LABORATORY TO STUDY THE EVOLUTIONARY DIVERGENCE OF FRESHWATER BIOTA. FIELD OBSERVATIONS SHOWED THAT BIOMPHALARIA SNAILS FROM PARINACOTA, COLPA, AND CAQUENA HAVE DIFFERENT SHELL SIZES. WE PERFORMED MORPHOMETRIC ANALYSIS AND COMMON GARDEN EXPERIMENT TO EVALUATE WHETHER THE OBSERVED SHELL VARIATION HAS A GENETIC BASE AND IF THIS VARIATION IS MANIFESTED IN OTHER MORPHOLOGICAL CHARACTERS AND LIFE HISTORY TRAITS.

THE REPRODUCTIVE CYCLE OF NON-NATIVE SPECIES IS INDICATIVE OF THEIR CAPACITY FOR DISPERSAL, INVASION, AND COMPETITION, AND THE ALTERATION IN BIODIVERSITY. CORBICULA SPP. ARE SUCCESSFUL INVADERS OF AQUATIC ECOSYSTEMS. WE STUDIED THE REPRODUCTIVE CYCLE OF CORBICULA LARGILLIERTI FROM A PAMPEAN STREAM, ARGENTINA, AT ITS SOUTHERN DISTRIBUTION IN SOUTH AMERICA. SPECIMENS WERE COLLECTED MONTHLY FROM JANUARY 2003 TO APRIL 2005 AND PROCESSED USING TRADITIONAL HISTOLOGICAL TECHNIQUES. THREE GONADAL STAGES (ACTIVE GAMETOGENESIS, MATURE, AND SPAWNED) WERE RECOGNIZED. IN THE STUDIED POPULATION, MOST INDIVIDUALS WERE HERMAPHRODITIC WITH A DOMINANT FEMALE GONADAL PORTION. THE THREE GONADAL STAGES WERE OBSERVED DURING THE WHOLE SAMPLING PERIOD WITH RAPID GONADAL RECOVERY; NO RESTING PERIOD WAS OBSERVED. FIVE OOCYTE SPAWNING EVENTS WERE RECOGNIZED, OCCURRING IN AUTUMN AND SPRING. EXPANDING THE KNOWLEDGE OF REPRODUCTIVE FEATURES OF THE CORBICULA LARGILLIERTI ALLOWS THE UNDERSTANDING OF CURRENT DISTRIBUTIONS. THE RESULTS HIGHLIGHT THE DIFFICULTY OF IDENTIFYING PATTERNS OF GAMETE RELEASE AND SPAWNING BEHAVIOR IN THIS INVASIVE SPECIES, AS IT IS RECORDED FOR OTHER CORBICULA SPP.

THE SOUTH AMERICAN BRACKISH WATER SNAIL HELEOBIA CHARRUANA (D'ORBIGNY, 1841), ABUNDANT IN URUGUAY, IS NEWLY RECORDED FOR THREE WESTERN EUROPEAN COUNTRIES: THE UNITED KINGDOM (2003), THE NETHERLANDS (2014) AND BELGIUM (2017). ITS IDENTITY WAS CONFIRMED USING MORPHOLOGICAL AND MOLECULAR METHODS. THE METHOD SUCCESSFULLY USED TO ISOLATE DNA AND TO FURTHER AMPLIFY AND SEQUENCE THE FULL MITOCHONDRIAL COI BARCODING FRAGMENT FROM AN OLD DRY SHELL WITHOUT DAMAGE IS DESCRIBED IN DETAIL. A SHORT SYNONYMY WITH REFERENCES TO THE MAIN LITERATURE IS PRESENTED. THE SPECIES' RANGE AND ECOLOGICAL DATA ARE REVIEWED FOR BOTH SOUTH AMERICA AND EUROPE AND THE IMPLICATIONS OF THE FINDS ARE DISCUSSED