Taxonomic implications of molecular studies on Northern Brazilian Teredinidae (Mollusca: Bivalvia) specimens

The current taxonomy of the Teredinidae (shipworms) is wholly based on morphology and up to now no molecular studies of the phylogeny of this group have been published. In the present study the relationships between four genera of the subfamilies Teredininae and Bankiinae were established and the efficiency of the 16S rRNA gene in characterizing four Teredinidae species was tested. Phylogenetic trees support the grouping of Bankia fimbriatula with Nausitora fusticula and of Neoteredo reynei with Psiloteredo healdi, but the genetic distances do not justify the classification of these species into two distinct subfamilies. The results show that B. fimbriatula, N. reynei and P. healdi specimens from the coast of the Brazilian state of Pará have five distinct 16S rRNA haplotypes, with one N. reynei haplotype differing from the other haplotypes in respect to at least seven sequences sites, indicating the existence of two very distinct sympatric lineages.

Seasonal abundance of the shipworm Neoteredo reynei (Bivalvia, Teredinidae) in mangrove driftwood from a northern Brazilian beach

Turus são importantes decompositores de madeira, especialmente em manguezais, onde a produtividade é alta. Entretanto, pouca ênfase tem sido dada à atividade de turus em relação à exportação de nutrientes de manguezais para as áreas costeiras adjacentes. Como um passo inicial para obter tais informações, a freqüência de madeira do mangue à deriva colonizada por turus, bem como a densidade e comprimento de turus, foram estudados através da coleta de troncos encalhados durante 12 meses na praia de Ajuruteua, Estado do Pará, norte do Brasil. Uma única espécie, Neoteredo reynei (Bartsch, 1920), foi encontrada colonizando a madeira à deriva. Embora troncos grandes colonizados fossem mais comuns na praia, a densidade de turus foi maior nos troncos menores, especialmente na estação seca. Em geral, a densidade foi maior durante a estação chuvosa (janeiro a abril) e menor em julho. O comprimento médio geral de turus foi de 9,66cm e, em troncos grandes, o comprimento médio aumentou entre as estações chuvosa e seca. Entretanto, não houve nenhuma diferença em comprimento entre as categorias de tamanho dos troncos. O comprimento médio dos turus foi semelhante ao longo do maior parte do ano, mas a tendência foi de comprimentos maiores em julho. Embora a salinidade tenha variado entre 10,9 e 40 durante o ano, nenhuma relação entre salinidade e densidade ou comprimento foi encontrada. Os resultados sugerem que a atividade de turus em madeira à deriva é relativamente constante ao longo do ano. Maior umidade do ar e precipitação podem promover sobrevivência durante a estação chuvosa. Troncos maiores podem levar mais tempo para serem colonizados e portanto podem ter densidades menores do que nos troncos menores. Estes últimos são incomuns talvez porque sejam rapidamente destruídos pela atividade dos turus. Dados sobre a desintegração de troncos, entretanto, seriam necessários para corroborar esta hipótese. O tamanho maior de turus na estação seca possivelmente esteja relacionado ao crescimento após um período anterior de recrutamento. Na estação seca, turus em troncos grandes podem ser melhor protegidos da dessecação e de altas temperaturas pelas propriedades isolantes do maior volume de madeira.

Ultraestrutura do espermatozóide de Protothaca pectorina (Lamarck) (Mollusca, Bivalvia) do litoral norte do Brasil

The ultrastructure of spermatozoa of the Protothaca pectorina (Lamarck, 1818) is described. The most significam differences were found in the structure and arreangement of the acrosomes, with contains two types of material, one fibrilar, the other electrondense granular. It is concluded that sperm ultrastructure is of the primitive type.

Estrutura fina do espermatozóide de Tagelus plebeius (Lightfoot) (Mollusca, Bivalvia) do litoral norte do Brasil

It is described the sperm ultraestructure differentiation during spermiogenesis of Tagelus plebeius (Lightfoot, 1786). The spermatozoon is an uniflagellated cell of the primitive type. The head region contains a rounded or conical nucleus surrounded by acrosome. The middle piece contains four mitochondria which are arranged around the axoneme. The flagellum contains the usual microtubular axoneme.

A new species of Chlamydoconcha Dall, 1884, from southeastern Brazil (Bivalvia: Chlamydoconchidae)

The second species in the genus Chlamydoconcha is described. Chlamydoconcha avalvis new species, occurs off the coast of Rio de Janeiro coast, in southeastern Brazil. The new species has very reduced valves acid a mantle surrounding the entire body, two features of the genus. The outer surface of the mantle lacks papillae except for a single cite located close to the excurrent siphon. These are distinctive characters of Chlamydoconcha orcutti Dall, 1884, from the eastern Pacific coast of North America, the single other known species of the genus. Some of the more interesting anatomical characters of the new species are: posterior pair of retractor muscles Of foot free front valves, absence of adductor muscles, gastric style sac totally separated from intestine, and the presence of a single (excurrent) siphon.

PLICATULOSTREA, A NEW GENUS OF PLICATULIDAE (BIVALVIA: PECTINOIDEA) FROM THAILAND

Plicatulostrea onca, a new genus and species of Plicatulidae, is described based on shell and anatomy. The samples were collected under intertidal rocks at Kungkrabaen Bay, Thailand. Plicatulostrea differs from other plicatulids mainly in lacking undulations or shell sculpture, by long projections of the hinge teeth of the right valve and extreme body compression. Plicatulostrea onca has a radially arranged spots at the shell surface and typical plicatulid anatomy, differing mainly by the richness of papillae on the mantle edge and by invasion of the gonad along the mantle lobes. Some comments on the anatomy of the family are also provided.

COMPARATIVE MORPHOLOGICAL STUDY OF SOME TELLINIDAE FROM THAILAND (BIVALVIA: TELLINOIDEA)

A comparative study of seven species of Tellinidae, collected at Kungkrabaen Bay, Gulf of Thailand, is presented. The species are Serratina capsoides (Lamarck, 1818), Moerella cf. Miens (Deshayes, 1854), Cadella cf. semen (Hanley, 1845), Pinguitellina cf. pinguis (Hanley, 1844), Elpidollina sp., and Tellinides timorensis (Lamarck, 1818) of the subfamily Tellininae, and Macomona sp. of the subfamily Macominae. With the objective of performing the study in a comparative and testable scenario, a phylogenetic analysis was carried out based on 43 morphological characters (94 states). A single cladogram was obtained as follows: (Serratina capsoides (Tellinides timorensis (Pinguitellina cf. pinguis (Cadella cf. semen (Moerella cf. Miens (Elpidollina sp. Macomona sp.)))))). A semelid and a solenid were operationally analyzed as part of the ingroup; polarisation was based on a plicatulid. In this analysis, Tellinoidea and Tellinidae were monophyletic, supported by 19 and 9 synapomorphies, respectively. Tellininae was paraphyletic. Good and significant morphological differences were found for all taxa, including at the species level. Some structures are reported for the first time, such as pseudogills, insertion of the pedal protractor dividing the anterior adductor muscle, and a circular muscle surrounding part of the anterior adductor muscle.

Anatomical description of Solen cf. exiguus DUNKER from Thailand (Bivalvia: Solenidae)

An anatomical description of the solenid Solen cf. exiguus DUNKER 1862, collected in the Gulf of Thailand, is provided. The anatomical features include high antero-posterior elongation; mantle lobes widely fused with each other; powerful pallial muscles; fused siphons with capacity of autotomy; wide and partially hollow foot; complete separation between gastric style sac and adjacent portion of intestine; all possible common characters of the family. Some so far exclusive attributes include short anterior pallial tentacles; pair of muscular valves at base of siphons; and arrangement of tentacles at siphonal tip. A short discussion on the taxonomy of the Solen exiguus/leanus complex is also included.

COMPARATIVE ANATOMICAL STUDY OF TWO SPECIES OF SEMELE FROM THAILAND (BIVALVIA: TELLINOIDEA)

An anatomical description of two semelids from Thailand is presented, based on samples from Kungkrabaen Bay, Gulf of Thailand. The species are Semele sinensis A. Adams, 1853, and S. carnicolor (Hanley, 1845), both with Indo-Pacific distributions. Morphology in these two species is typically tellinoidean, each with a long internal ligamental element (resilium), a distance between the inner fold of the mantle edge and the other two folds, long and branched gastric ducts to the digestive diverticula, and a stomach diverticulum located in the posterodorsal corner of the gastric chamber, projecting posteriorly. The main anatomical differentiation between the two species is in the character of the labial palps.

Revision of the genus Spinosipella (Bivalvia : Verticordiidae), with descriptions of two new species from Brazil

A revision of the deep-water verticordiid genus Spinosipella is provided, based on conchological and anatomical characters. The genus is considered distinct from Verticordia (of which it was considered a subgenus) based on the strong ribs, prickly surface, reduction of lunula, relative large size, weakly spiral valve shape, and other characters. The following species are considered in the genus: (1) Spinosipella agnes new species, ranging from Florida, USA, to Rio de Janeiro, Brazil, and also including the Porcupine Abyssal Plain in the North Atlantic; (2) S. tinga new species, occurring from Rio de Janeiro to Rio Grande do Sul, Brazil; (3) S. acuticostata (Philippi, 1844), a Pliocene fossil from southern Italy; (4) S. deshayesiana (Fischer, 1862), from south and central Indo-Pacific (S. ericia Hedley, 1911, the type species of the genus, was revealed to be a new synonym of S. deshayesiana); and (5) S. costeminens (Poutiers, 1981), from the tropical west Pacific. The five species differ mainly in conchological details of the number and size of ribs, of the prickly sculpture, shape of the shell, of the hinge and the degree of convexity. Anatomical description is also provided for the two Pacific species, which differ among themselves mainly by the size of the pair of renal folds. From the standpoint of anatomical characters, the more significant are: the wide lithodesma; the elongation of the auricles, crossing the roof of pallial cavity; a tall digital fold in posterior region of supraseptal chamber; the low but wide palps; the muscular, gizzard-like stomach; the complete separation of both constituents of the hermaphroditic gonad (a ventro-posterior testicle and a centro-dorsal ovary), and a complete fusion of the visceral ganglia.

Early development, survival and growth rates of the giant clam Tridacna crocea (Bivalvia: Tridacnidae)

Tridacnid clams are conspicuous inhabitants of Indo-Pacific coral reefs and are traded and cultivated for the aquarium and food industries. In the present study, daily growth rates of larvae of the giant clam Tridacna crocea were determined in the laboratory during the first week of life. Adults were induced to spawn via intra-gonadal serotonin injection through the byssal orifice. After spawning oocytes were collected, fertilized and kept in 3 L glass beakers and raceways treated with antibiotics to avoid culture contamination. Larvae were fed twice with the microalga Isochrysis galbana and zooxanthellae were also offered twice during the veliger stage (days 4 and 6). Larval length was measured using a digitizing tablet coupled to a microcomputer. Larval mortality was exponential during the first 48 hours of life declining significantly afterwards. Mean growth rate was 11.3 mu m day-1, increasing after addition of symbionts to 18.0 mu m day-1. Survival increased to ca. 75% after the addition of zooxanthellae. The results describe the growth curve for T. crocea larvae and suggest that the acquisition of symbionts by larvae may be useful for larval growth and survival even before larvae have attained metamorphosis.

Nuculidae (Bivalvia) in the Cape Melville Formation, King George Island, Antarctica, with an overview of the bivalve fauna

Nuculid bivalves of the Cape Melville Formation (Early Miocene, King George Island) are reviewed. Ten bivalve taxa are listed from the formation in the families Nuculidae (two species), Sareptidae, Malletiidae, Limopsidae (two species), Limidae, Pectinidae, Hiatellidae, and Periplomatidae. The Nuculidae consist of two species of Leionucula Quenstedt, 1930. One of these, L. melvilleana n. sp., is described and the other consists of the two species named previously by Anelli et al. (2006), which are demonstrated to be synonymous and are assigned to the species Leionucula frigida (Anelli, Rocha-Campos, Santos, Perinotto & Quaglio 2006). This assemblage, dominated by protobranchs (89% of specimens), is a typical fauna of offshore soft substrates, with a few specimens transported from hard substrates nearby. The diversity of Nuculidae has decreased in the Antarctic region through the Cenozoic.

Early development, survival and growth rates of the giant clam Tridacna crocea (Bivalvia: Tridacnidae)

Tridacnid clams are conspicuous inhabitants of Indo-Pacific coral reefs and are traded and cultivated for the aquarium and food industries. In the present study, daily growth rates of larvae of the giant clam Tridacna crocea were determined in the laboratory during the first week of life. Adults were induced to spawn via intra-gonadal serotonin injection through the byssal orifice. After spawning oocytes were collected, fertilized and kept in 3 L glass beakers and raceways treated with antibiotics to avoid culture contamination. Larvae were fed twice with the microalga Isochrysis galbana and zooxanthellae were also offered twice during the veliger stage (days 4 and 6). Larval length was measured using a digitizing tablet coupled to a microcomputer. Larval mortality was exponential during the first 48 hours of life declining significantly afterwards. Mean growth rate was 11.3 μm day-1, increasing after addition of symbionts to 18.0 μm day-1. Survival increased to ca. 75% after the addition of zooxanthellae. The results describe the growth curve for T. crocea larvae and suggest that the acquisition of symbionts by larvae may be useful for larval growth and survival even before larvae have attained metamorphosis.

Mitochondrial Genomics: structure, inheritance and phylogenetic utility of the Mitochondrial genome in Bivalvia and Insecta

This PhD Thesis is the result of my research activity in the last three years. My main research interest was centered on the evolution of mitochondrial genome (mtDNA), and on its usefulness as a phylogeographic and phylogenetic marker at different taxonomic levels in different taxa of Metazoa. From a methodological standpoint, my main effort was dedicated to the sequencing of complete mitochondrial genomes, and the approach to whole-genome sequencing was based on the application of Long-PCR and shotgun sequences. Moreover, this research project is a part of a bigger sequencing project of mtDNAs in many different Metazoans’ taxa, and I mostly dedicated myself to sequence and analyze mtDNAs in selected taxa of bivalves and hexapods (Insecta). Sequences of bivalve mtDNAs are particularly limited, and my study contributed to extend the sampling. Moreover, I used the bivalve Musculista senhousia as model taxon to investigate the molecular mechanisms and the evolutionary significance of their aberrant mode of mitochondrial inheritance (Doubly Uniparental Inheritance, see below). In Insects, I focused my attention on the Genus Bacillus (Insecta Phasmida). A detailed phylogenetic analysis was performed in order to assess phylogenetic relationships within the genus, and to investigate the placement of Phasmida in the phylogenetic tree of Insecta. The main goal of this part of my study was to add to the taxonomic coverage of sequenced mtDNAs in basal insects, which were only partially analyzed.

Impatto degli interventi antropici di difesa costiera sulla struttura e distribuzione della popolazione di Lentidium mediterraneum (Mollusca bivalvia)

Il presente elaborato si inserisce all’interno del progetto THESEUS (Innovative Technologies for safer European coasts in a changing climate), nella sezione denominata “work package 3”. I principali obiettivi di questo studio sono: 1) valutare l’impatto delle differenti strategie di difesa di zone intertidale dell’ecosistema spiaggia lungo il litorale dell’Emilia-Romagna; 2) analizzare nel dettaglio la struttura e la distribuzione del microbivalve Lentidium mediterraneum, tipico do questa zona, per valutarne un eventuale utilizzo nei progetti di monitoraggio e analisi degli impatti antropici legati alle variazioni morfodinamiche. Sono state scelte tre spiagge: Cesenatico, in cui da molti anni sono presenti strutture di difesa rigide della spiaggia, e dove ogni anno, al termine della stagione estiva, vengono costruite delle dune artificiali, rimosse a fine primavera, per proteggere gli stabilimenti balneari dalle mareggiate invernali; Cervia, in cui sono presenti solo le dune artificiali stagionali; Lido di Dante, considerato naturale per l’assenza di strutture di protezione. Il campionamento è stato effettuato in 3 tempi per ciascun sito. 2 tempi senza le dune artificiali, e uno con. Per ciascun sito e ciascun tempo sono stati replicati 3 transetti, random, per ogni livello di marea. Sono stati prelevati campioni per un totale di 14879 individui e identificati 40 taxa. Da questi sono stati estratti gli esemplari di Lentidium mediterraneum da analizzare. Le analisi uni e multivariate effettuate sull’intera comunità hanno messo in evidenza differenze fra le spiagge, fra i tempi di campionamento e i livelli di marea. Si è, inoltre evidenziato come tali differenze fossero in parte dovute alle densità di Lentidium mediterraneum. Oltre alle analisi classiche nel presente lavoro di tesi è stato proposto un modello concettuale di trasporto del Lentidium mediterraneum che se validato confermerebbe la possibilità di utilizzare il microbivalve come “proxy biologico”.