Comparative studies on the histology and ultrastructure of the siphons of two species of Tellinidae (Mollusca: Bivalvia) from Brazil

Despite the great importance of the siphons for infaunal bivalves, only a few studies have examined their tissues using histology techniques or scanning electron microscopy. In the present study, the siphons of Tellina lineata Turton, 1819 and Macoma biota Arruda & Domaneschi, 2005 were investigated. The siphon walls are composed by a series of muscle sheets of longitudinal (L), circular (C) and radial (R) fibers, with a clear pattern common to both species: there is a main median longitudinal layer (Lm), and two peripheral circular layers, one inner (Ci) and one outer (Co), near the epithelia. A median circular layer (Cm) separates an internal (Lmi) from an outer (Lmo) median longitudinal layer. Further, the Co is split by a thin outer longitudinal layer (Lo), forming Coi and Coo layers, the former being obliquely oriented. Thin radial fibers (R) delimit clear packages of Lmi and Lmo fibers. In each siphon, there are six longitudinal nerve cords, running within the Lmi layer, adjacent to the Cm. The inhalant and exhalant siphons of M. biota are very similar in structure, but the Lmo of the exhalant siphon is almost twice as thick as its Lmi, while in the inhalant siphon these layers have similar thicknesses; the Coi is very thick, especially in the exhalant siphon. The inhalant siphon of T. lineata is very similar to that of M. biota, differing only with respect to the thickness of the Coi, which in the former species is not as well developed as in the latter. The Lmo of the exhalant siphon of T. lineata is by far the most developed layer, with the Lmi represented only by uniseriate small cells; in the vicinities of the nerve cords, the Cm is split in two layers. The epithelia of both siphons of M. biota and T. lineata bear ciliated receptors, which were difficult to observe as they were frequently covered with mucus. It was possible to observe that cilia are present in both species, differing in length and in the number per receptor between the inhalant and exhalant siphons, and between the species. Detailed comparisons among the siphons of M. biota and T. lineata and other bivalve species are very difficult, because of at least two reasons. First, each investigator has used different methods to prepare and observe the siphons through histological sections; and second, different nomenclatural schemes are used to describe the musculature of the siphons, causing confusion when the same layers are compared among different species. In order to unify the nomenclature of tissue layers of the bivalve siphons, we now propose a scheme to name these layers based on topological homology.21922

Levantamento de Polychaeta (Annelida) na Baía do Almirantado, Ilha Rei George (Antártica)

Foram estudados os Polychaeta coletados durante três Expedições Oceanografcias brasilaeiras a Antarticia (Dezembro - 1996 a Janeiro - 1997; Dezembro - 1997 a Janeiro - 1998; Janeiro a Abril - 2001) para a Baia do Almirantado. Um total de 127 espécimes foi examinado e 18 espécies, pertencentes a 12 famílias, foram identificados. A família Terebellidae foi a que apresentou o maior número de espécies, e Terebellidae, Nephtyidae e Polynoidae apresentaram os maiores número de indivíduos coletados. As espécies Terebellides longicaudatus e Aglaophamus trissophyllus foram reportadas pela primeira vez na Baía e os gêneros Proclea (Terebellidae), Neanthes (Nereididae), Bradabyssa (Flabelligeridae), Euclymene (Maldanidae), foram reportados pela primeira vez na enseada de Martel.The Polychaeta collected during three distinct Brazilian Antarctic Expeditions (December 1996 to January-1997; December 1997 to January 1998; January to April 2001) in the Admiralty Bay have been studied. A total of 127 specimens have been examined and 18 species, belonging to 12 families, have been identified. The family Terebellidae was the most important family in number of species, and Terebellidae, Nephtyidae and Polynoidae in number of individuals. The species Terebellides longicaudatus and Aglaophamus trissophyllus were reported from the first time to the Bay and the genera Proclea (Terebellidae), Neanthes (Nereididae), Bradabyssa (Flabelligeridae), Euclymene (Maldanidae) were reported from the first time in the Martel Inlet

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Distribuição Do Carbono Orgânico Nas Frações Do Solo Em Diferentes Ecossistemas Na Amazônia Central

Organic matter plays an important role in many soil properties, and for that reason it is necessary to identify management systems which maintain or increase its concentrations. The aim of the present study was to determine the quality and quantity of organic C in different compartments of the soil fraction in different Amazonian ecosystems. The soil organic matter (FSOM) was fractionated and soil C stocks were estimated in primary forest (PF), pasture (P), secondary succession (SS) and an agroforestry system (AFS). Samples were collected at the depths 0-5, 5-10, 10-20, 20-40, 40-60, 60-80, 80-100, 100-160, and 160-200 cm. Densimetric and particle size analysis methods were used for FSOM, obtaining the following fractions: FLF (free light fraction), IALF (intra-aggregate light fraction), F-sand (sand fraction), F-clay (clay fraction) and F-silt (silt fraction). The 0-5 cm layer contains 60% of soil C, which is associated with the FLF. The F-clay was responsible for 70% of C retained in the 0-200 cm depth. There was a 12.7 g kg-1 C gain in the FLF from PF to SS, and a 4.4 g kg-1 C gain from PF to AFS, showing that SS and AFS areas recover soil organic C, constituting feasible C-recovery alternatives for degraded and intensively farmed soils in Amazonia. The greatest total stocks of carbon in soil fractions were, in decreasing order: (101.3 Mg ha-1 of C - AFS) > (98.4 Mg ha-1 of C - FP) > (92.9 Mg ha-1 of C - SS) > (64.0 Mg ha-1 of C - P). The forms of land use in the Amazon influence C distribution in soil fractions, resulting in short- or long-term changes. © 2015, Revista Brasileira de Ciencia do Solo. All rights reserved

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

The use of micro-Computed Tomography as a minimally invasive tool for anatomical study of bivalves (Mollusca: Bivalvia). Zoological Journal of the Linnean Society

Micro-computed tomography or micro-CT is a minimally invasive technique capable of generating 2D images and 3D tomographic reconstructions of small-sized animals without destroying the physical specimens. The technique has been previously applied to the study of bivalves, and here we extend it to study the anatomy of eight anomalodesmatan species through the exclusive use of a tomographic approach. Freshly fixed and museum specimens of Anomalodesmata, one of the least understood clades of bivalves, were selected and scanned. Tomographic anatomical descriptions were generated for Pandora pinna (Pandoridae), Lyonsia alvarezii (Lyonsiidae), Allogramma formosa (Lyonsiellidae), Trigonulina ornata (Verticordiidae), Poromya rostrata (Poromyidae), Cetoconcha spinosula, Cetoconcha aff. smithii (Cetoconchidae) and Cuspidaria glacialis (Cuspidariidae). The main internal anatomical features often evaluated for anomalodesmatans were documented. The tomographic images allowed for a detailed description of anatomical structures, including the mantle, ctenidia, labial palps and siphons, as well as the digestive, reproductive and nervous systems. This non-destructive technique thus proved to be an efficient tool for describing the anatomy of bivalves. The potential of micro-CT in concert with the constant development of new scanners, bring fresh perspectives to the anatomical study of bivalves. Poromya spinosula is transferred to Cetoconcha and Cetoconchidae, as Cetoconcha spinosula (Thiele, 1912) comb. nov

Type specimens of Caudofoveata (Mollusca, Aplacophora) in the molluscan collections of the National Museum of Natural History, Smithsonian Institution and of the Museum of Comparative Zoology, Harvard University

Miranda, Marcel S., Strong, Ellen E., Passos, Flávio D. (2020): Type specimens of Caudofoveata (Mollusca, Aplacophora) in the molluscan collections of the National Museum of Natural History, Smithsonian Institution and of the Museum of Comparative Zoology, Harvard University. Zootaxa 4895 (4): 581-593, DOI: https://doi.org/10.11646/zootaxa.4895.4.