RESUMO
The scalpellomorph barnacle, Aurivillialepas calycula (Aurivillius, 1898), previously known only from Macaronesia, is reported from Banco de Galicia, off the NW corner of the Iberian Peninsula. One of the two specimens was attached to the scleractinian coral, Madrepora oculata Linnaeus, 1758. Since such pedunculate barnacles are little known, the potentially hermaphroditic specimens and its complemental male are illustrated photographically, and a key to the genus Aurivillialepas is provided. The genus, together with Scillaelepas Seguenza, 1876 and Gruvelialepas Newman, 1980, has long been considered to constitute a natural group of scalpellomorphs within the Calanticidae, and therefore the Scillaelepadinae subfam. nov. is proposed to accommodate them. Biogeographical aspects of these deep-sea barnacles support the hypothesis that not only the islands but the banks and guyots of Macaronesia constitute refugia for ancient as well as more recent forms, some of which may stem back to the late Mesozoic.
Assuntos
Thoracica/classificação , Distribuição Animal , Estruturas Animais/anatomia & histologia , Estruturas Animais/crescimento & desenvolvimento , Animais , Antozoários/fisiologia , Tamanho Corporal , Feminino , Masculino , Tamanho do Órgão , Thoracica/anatomia & histologia , Thoracica/crescimento & desenvolvimentoRESUMO
The fossil history of turtle and whale barnacles (Coronuloidea: Chelonibiidae, Platylepadidae, Coronulidae and Emersoniidae) is fragmentary and has only been investigated in part. Morphological inferences and molecular phylogenetic analyses on extant specimens suggest that the roots of whale barnacles (Coronulidae) are to be found among the chelonibiid turtle barnacles, but the hard-part modifications that enabled early coronuloids to attach to the cetacean skin are still largely to be perceived. Here, we reappraise a fossil chelonibiid specimen from the Miocene of insular Tanzania that was previously referred to the living species Chelonibia caretta. This largely forgotten specimen is here described as the holotype of the new species Chelonibia zanzibarensis. While similar to C. caretta, C. zanzibarensis exhibits obvious external longitudinal parietal canals occurring in-between external longitudinal parietal septa that abut outwards to form T-shaped flanges, a character so far regarded as proper of the seemingly more derived Coronulidae and Platylepadidae. Along with these features, the presence of a substrate imprint on the shell exterior indicates that C. zanzibarensis grasped its host's integument in much the same way as coronulids and platylepadids, albeit without the development of macroscopic parietal buttresses and bolsters. Thin section analyses of the inner parietal architecture of some extant and extinct coronuloids conclusively demonstrate that vestiges of comparable external parietal microstructures are present in some living members of Chelonibiidae. This observation strengthens the unity of Coronuloidea while significantly contributing to our understanding of the evolution of the coronuloid shell structure in adapting to a diverse spectrum of hosts.
Assuntos
Exoesqueleto , Evolução Biológica , Fósseis , Thoracica , Tartarugas , Animais , Filogenia , TanzâniaRESUMO
The scientific names of living organisms can and do sometimes change. Such changes generally reflect advances in knowledge of the relationships of species and/or higher taxa. The new name, Amphibalanus amphitrite (subfamily Amphibalaninae), for a well-known fouling barnacle previously known as Balanus amphitrite (subfamily Balaninae), was proposed in accordance with the International Code of Zoological Nomenclature and is now widely accepted. Clare and Høeg (2008) criticise this change but offer no scientifically valid reason to return to the earlier nomenclature of this or any other well-known species of barnacle.
Assuntos
Thoracica/classificação , Animais , Especificidade da EspécieRESUMO
Curious eroded depressions, most resembling an eye shedding an elongate tear, are found in gently sloping, intertidal, carbonate-rich arenite outcropping on the sea coast near Lakes Entrance, Victoria, southeast Australia. The depressions, known locally as "Tears of the Virgin," are evidently formed by multiple generations of a barnacle, Chthamalus antennatus Darwin, 1854 in association with cyanobacteria. While the round part of a depression offers the barnacle a modicum of protection from impacts during high tides, it is also partially inhabited by cyanobacteria, which extend into and tend to fill the elongate tear. As such, this appears to be the first case of mutualism between a higher invertebrate and cyanobacteria, with the cyanobacteria reducing the barnacle's risk of desiccation while receiving metabolic wastes from it during low tides. It is also the first record of a balanomorph barnacle eroding calcareous arenite beneath its shell, the net effect of which would be expected to reduce its adhesion to the substrate. However, the siliceous residue, resulting from the barnacle's dissolution of the more than 80% of the calcite-rich sedimentary rock, is sequestered in delicate folds on the inside of the shell wall as it grows. A brief review of cirripedes capable of excavation includes the first photographic documentation of excavation of a mollusc shell by a verrucomorph.
Assuntos
Cianobactérias , Thoracica , Animais , Austrália , Geologia , LagosRESUMO
A new genus, Zevinaella (Cirripedia: Scalpellomorpha: Scalpellidae: Arcoscalpellinae), is proposed to accommodate Trianguloscalpellum rodstromi (Boone, 1927) from Belize and Z. volentis gen. et sp. nov. from the Lesser Antilles, both occurring on crinoids. These two species are unique in lacking lower lateral plates (inframedian or second latera, L2s). We see no compelling evidence that the lack of L2s in Zevinaella is a consequence of fusion with the carinolatera (CLs), as appears to be the case in a near relative T. pentacrinarum, or of progressive reduction and potential loss, as in older specimens of Amigdoscalpellum spp. (Zevina, 1978b). However, this does not weaken the diagnosis of the new genus and, accordingly, the diagnoses for the family Scalpellidae Pilsbry, 1907 and the subfamily Arcoscalpellinae Zevina, 1978b are amended to accommodate the absence of the L2s.
Assuntos
Equinodermos/fisiologia , Thoracica , Animais , Região do Caribe , Thoracica/anatomia & histologia , Thoracica/classificação , Thoracica/fisiologiaRESUMO
A number of stylasterid corals are known to act as host species and create refuges for a variety of mobile and sessile organisms, which enhances their habitat complexity. These include annelids, anthozoans, cirripeds, copepods, cyanobacteria, echinoderms, gastropods, hydroids and sponges. Here we report the first evidence of a diverse association between stylasterids and scalpellid pedunculate barnacles and describe a new stylasterid species, Errinalabrosa, from the Tristan da Cunha Archipelago. Overall, five stylasterid species are found to host eight scalpellid barnacles from several biogeographic regions in the southern hemisphere (Southern Ocean, temperate South America and the southern Indo-Pacific realms). There is an apparent lack of specificity in this kind of association and different grades of reaction to the symbiosis have been observed in the coral. These records suggest that the association between pedunculate barnacles and hard stylasterid corals has a wide distribution among different biogeographic realms and that it is relatively rare and confined largely to deep water.