Shell morphometrics of three species of gadilid Scaphopoda (Mollusca) from the Southwestern Atlantic Ocean: comparing the discriminating power of primary and secondary descriptors

Zootaxa ◽  
2004 ◽  
Vol 706 (1) ◽  
pp. 1 ◽  
Author(s):  
RICARDO SILVA ABSALÃO ◽  
THIAGO SILVA DE PAULA
Keyword(s):  
Atlantic Ocean ◽  
Discriminant Function Analysis ◽  
Shell Length ◽  
Function Analysis ◽  
Southwestern Atlantic ◽  
Morphometric Data ◽  
Maximum Width ◽  
Discriminating Power ◽  
Southwestern Atlantic Ocean ◽  
Mollusc Species

Shell morphometric data are potentially useful in discriminating among morphologically similar mollusc species. Only a few studies, however, have assessed the value of this method for identifying and delimiting scaphopod taxa. We attempted to discriminate three southwestern-Atlantic species of gadilid scaphopods, Gadila acus (Dall, 1889), Cadulus braziliensis Henderson, 1920, and Polyschides tetraschistus (Watson, 1879) using Discriminant Function Analysis of shell morphometric data. We tested the efficiency of three morphometric indices proposed by Shimek (1989), nine direct shell measurements proposed by Steiner & Linse (2000), and three newly proposed morphometric indices. Shimek s (1989) indices correctly assigned 133 of 150 specimens (88.67%), whereas the direct shell measurements data correctly assigned 149 specimens (99.34%). The most efficient set of parameters assigning all specimens correctly consisted of: 1) the height of the posterior aperture, 2) the total length of the shell, 3) the maximum arc, 4) the ratio of total shell length and the distance from the dorsal aperture to the point of maximum width, 5) the ratio of the maximum shell diameter and the apertural diameter, and 6) the ratio of the height and width of the posterior aperture. Because this combination of variables was 100% efficient in discriminating among the three species, we recommend its use as the best tool for separating these slender gadilid scaphopods.

scholarly journals Shell morphometrics in four species of Gadilidae (Mollusca, Scaphopoda) in Southwestern Atlantic Ocean, Brazil

2005 ◽  
Vol 22 (1) ◽  
pp. 175-179 ◽  
Author(s):  
Ricardo Silva Absalão ◽  
Pedro Henrique de Almeida Silva ◽  
Thiago Silva de Paula
Keyword(s):  
Atlantic Ocean ◽  
Shell Length ◽  
Small Samples ◽  
Pairwise Comparisons ◽  
Southwestern Atlantic ◽  
Maximum Width ◽  
Direct Measurements ◽  
Combined Use ◽  
Southwestern Atlantic Ocean ◽  
Morphometric Index

Six morphometric shell direct measurements of the Gadilidae species Gadila acus (Dall, 1889), Cadulus braziliensis Henderson, 1920, Cadulus parvus Henderson, 1920 and Polyschides tetraschistus (Watson, 1879) were carried out and used to build three morphometric indices in according to the proposition of SHIMEK (1989): LI, relating total shell length to length from the dorsal aperture to the maximum width; WI, relating maximum shell diameter to apertural diameter; and Ws, whorl expansion rate (sensu RAUP 1966). Direct measurements and morphometric indices were tested as discriminating tools among the four species. None of the morphometric indices, alone, were able to discriminate among all species. Among then, Ws is not an effective discriminating morphometric index because it fails in all pairwise comparisons, LI and WI are fairly efficient ones, since they have got effective discriminations in three out six pairwise comparisons. The combined use of direct measurements ones was more efficient than the indices ones when dealing with relatively small samples, as ours. Although both descriptors can be combiningly used; since the direct measurements descriptors are easier to obtain and understand than the more complex indices, they should be recommended as main tools.

Population structure and ontogenetic habitat use of Micropogonias furnieri in the Southwestern Atlantic Ocean inferred by otolith chemistry

2021 ◽  
Vol 240 ◽  
pp. 105953
Author(s):  
Esteban Avigliano ◽  
Nadia M. Alves ◽  
M. Rita Rico ◽  
Claudio O. Ruarte ◽  
Luciana D’Atri ◽  
...  
Keyword(s):  
Population Structure ◽  
Atlantic Ocean ◽  
Habitat Use ◽  
Otolith Chemistry ◽  
Southwestern Atlantic ◽  
Southwestern Atlantic Ocean ◽  
Micropogonias Furnieri

scholarly journals Abundance and demography of bottlenose dolphins inhabiting a subtropical estuary in the Southwestern Atlantic Ocean

2015 ◽  
Vol 96 (2) ◽  
pp. 332-343 ◽  
Author(s):  
Pedro F. Fruet ◽  
Fábio G. Daura-Jorge ◽  
Luciana M. Möller ◽  
Rodrigo Cezar Genoves ◽  
Eduardo R. Secchi
Keyword(s):  
Atlantic Ocean ◽  
Bottlenose Dolphins ◽  
Southwestern Atlantic ◽  
Southwestern Atlantic Ocean ◽  
Subtropical Estuary

Taxonomy of the genus Thyonella (Holothuroidea: Dendrochirotida), with mention of the first record of T. sabanillaensis from the southwestern Atlantic Ocean

Zootaxa ◽  
2018 ◽  
Vol 4527 (1) ◽  
pp. 75
Author(s):  
LUCIANA MARTINS
Keyword(s):  
Pacific Ocean ◽  
Atlantic Ocean ◽  
First Record ◽  
Morphological Characters ◽  
Sem Analysis ◽  
Southwestern Atlantic ◽  
Internal Morphology ◽  
The Pacific ◽  
Southwestern Atlantic Ocean ◽  
The Pacific Ocean

The genus Thyonella currently comprises four species which occur in the Atlantic and Pacific Oceans. Thyonella mexicana is the only species known to occur in the Pacific Ocean. The main morphological characters used to distinguish Thyonella species are their dermal ossicles. Since the differences among these characters are subtle, this contribution provides a detailed description and comparison of the ossicle assemblage of the concerned taxa. In addition, description of the internal morphology of three of the concerned species is also provided. Further, this study reports on the first record of Thyonella sabanillaensis for the Southwestern Atlantic. A worldwide revision of the distributional records of Thyonella species is presented and their taxonomy is discussed, concluding that some traditional taxonomic characters should be used cautiously. A brief discussion about the importance of SEM analysis is also provided. 

scholarly journals Classification of fish and non-fish acoustic tracks using discriminant function analysis

2012 ◽  
Vol 69 (2) ◽  
pp. 313-322 ◽  
Author(s):  
Yunbo Xie ◽  
Catherine G. J. Michielsens ◽  
Fiona J. Martens
Keyword(s):  
Discriminant Function ◽  
Discriminant Function Analysis ◽  
Function Analysis ◽  
Fish Populations ◽  
Fraser River ◽  
Discriminating Power ◽  
Sonar System ◽  
Stationary Objects ◽  
Individual Variables

Abstract Xie, Y., Michielsens, C. G. J., and Martens, F. J. 2012. Classification of fish and non-fish acoustic tracks using discriminant function analysis. – ICES Journal of Marine Science, 69: 313–322. Hydroacoustic data acquired for estimating fish populations contain information on both fish and non-fish targets, so sonar technicians traditionally rely on their knowledge of fish behaviour and experience with hydroacoustics to remove non-fish targets from the hydroacoustic data. This process is often labour-intensive and time-consuming, making real-time assessment of fish populations difficult. Simple solutions are not always available for all circumstances. However, the split-beam sonar data collected in the lower Fraser River, British Columbia, Canada, showed distinct signatures between actively swimming fish and non-fish objects such as drifting debris, surface bubbles, and stationary objects in the water column and off the river bottom. Acoustic tracks of fish and non-fish targets were characterized by differentiable statistical patterns that were amenable to discriminant function analysis (DFA). An application of DFA to segregate fish and non-fish targets detected by a split-beam sonar system in the lower Fraser River is presented, characteristics of user-identified fish and non-fish acoustic tracks being utilized as learning samples for the DFA. Also, a method to rank the discriminating power of individual variables is presented, providing guidance for constructing efficient and effective discriminant functions with variables that offer high discriminating power. The DFA yielded classification accuracies of 96% for fish and 91% for non-fish tracks and reduced the manual sorting time by 50–75%.

Tissue distribution of heavy metals in small cetaceans from the Southwestern Atlantic Ocean

1990 ◽  
Vol 21 (6) ◽  
pp. 299-304 ◽  
Author(s):  
Jorge E. Marcovecchio ◽  
Víctor J. Moreno ◽  
Ricardo O. Bastida ◽  
Marcela S. Gerpe ◽  
Diego H. Rodríguez
Keyword(s):  
Heavy Metals ◽  
Atlantic Ocean ◽  
Tissue Distribution ◽  
Southwestern Atlantic ◽  
Southwestern Atlantic Ocean

Two new species of Sclerothyone from the southwestern Atlantic Ocean, with a key to genera and species of Sclerothyoninae (Holothuroidea: Dendrochirotida: Sclerodactylidae)

Zootaxa ◽  
2019 ◽  
Vol 4658 (2) ◽  
pp. 375-382
Author(s):  
LUCIANA MARTINS ◽  
MARCOS TAVARES
Keyword(s):  
New Species ◽  
Atlantic Ocean ◽  
South African ◽  
Body Wall ◽  
Circular Disc ◽  
Southwestern Atlantic ◽  
African Species ◽  
Southwestern Atlantic Ocean ◽  
Two New Species ◽  
Tube Feet

Sclerothyone Thandar, 1989, currently restricted to two South African species, is here expanded to include two new species from off coast of Brazil. These new species expand the distribution of the genus to the southwestern Atlantic Ocean. Sclerothyone reichi sp. nov. is characterized by having body wall with multilocular two pillared tables with multiperforate disc and short spire, ending in a narrow crown of teeth; tentacles with rods and introvert with two pillared tables and rosettes; tube feet with only end plates. Sclerothyone oloughlini sp. nov. is distinctive in having a body wall with multilocular, two pillared tables; handles present and multilocular two-pillared tables; circular disc without handle; and plates (near the anus). The new species resemble each other in the tentacles with rods. However, Sclerothyone oloughlini sp. nov. stands apart from S. reichi sp. nov. in the introvert with rosettes; tube feet with two pillared supporting tables, arched plates and end plates. The possible assignment of Cucumaria nozawai Mitsukuri, 1912 and Thyone adinopoda Pawson & Miller, 1981 to Sclerothyone, and the position of Thyone neofusus Deichmann, 1941 in Temparena Thandar, 1989, are briefly discussed. A key to all genera and species of Sclerodactylinae is provided.

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