Abstract:Despite the increasing number of reports on the deep-sea molluscs from the south-western Atlantic, we know very little about the protobranchs. The lack of information on the protobranch Pelecypoda off southern Brazil is reflected in the genus Yoldiella. This contribution is part of an effort to increase the knowledge about this group off the Brazilian coast. Eight species of Yoldiella are recognized here. For Yoldiella biguttata, previously reported from Brazil, the known distribution is extended southwards to… Show more
“…One may argue that the degree of taxonomic uncertainty associated with these taxa would invalidate the whole statistical analysis, considering that the specific status could be uncertain. However, Benaim & Absalão (2010) have already elucidated this issue. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Having all taxa previously defined, according to traditional criteria largely based on shell shape subjective perception (see Benaim & Absalão, 2011), and facing this identification proposal as a hypothesis to be tested, we performed a validation test. For this purpose a multivariate approach was carried out utilizing discriminant function analysis (DFA) to integrate all morphometric data in a single analysis, with the specific aims of: (1) to corroborate or not our previous identification; (2) to illustrate quantitative diagnostic features for the species and clusters of species; and (3) to assess which of the analysed features were the most important for the discrimination of these species.…”
Eight species ofYoldiella(Yoldiella biguttataAllen, Sanders & Hannah, 1995;Yoldiella similisAllen, Sanders & Hannah, 1995;Yoldiella extensaAllen, Sanders & Hannah, 1995;Yoldiellaaff.jeffreysi(Hidalgo, 1877);Yoldiellasp.1;Yoldiellasp. 2;Yoldiellasp. 3 andYoldiellasp. 4) from the continental slope off Rio de Janeiro were used to test if quantitative morphometric measurements of shell shape and hinge plate could effectively discriminate among them. Thirty specimens of each species were sampled, and a total of 25 variables were established and utilized as input data to perform a discriminant analysis. The percentage of correctly classified cases was never less than 80%. The hinge plate variables were always relevant, and the most important one was the width of the posterior hinge plate. On the other hand, shell shape variables, when present, were secondary. Considering that the variation in the shell ofYoldiellaspecies is subtle, and also the findings of this study, we can state that the hinge plate morphometry has good potential to improve species discrimination.
“…One may argue that the degree of taxonomic uncertainty associated with these taxa would invalidate the whole statistical analysis, considering that the specific status could be uncertain. However, Benaim & Absalão (2010) have already elucidated this issue. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…Having all taxa previously defined, according to traditional criteria largely based on shell shape subjective perception (see Benaim & Absalão, 2011), and facing this identification proposal as a hypothesis to be tested, we performed a validation test. For this purpose a multivariate approach was carried out utilizing discriminant function analysis (DFA) to integrate all morphometric data in a single analysis, with the specific aims of: (1) to corroborate or not our previous identification; (2) to illustrate quantitative diagnostic features for the species and clusters of species; and (3) to assess which of the analysed features were the most important for the discrimination of these species.…”
Eight species ofYoldiella(Yoldiella biguttataAllen, Sanders & Hannah, 1995;Yoldiella similisAllen, Sanders & Hannah, 1995;Yoldiella extensaAllen, Sanders & Hannah, 1995;Yoldiellaaff.jeffreysi(Hidalgo, 1877);Yoldiellasp.1;Yoldiellasp. 2;Yoldiellasp. 3 andYoldiellasp. 4) from the continental slope off Rio de Janeiro were used to test if quantitative morphometric measurements of shell shape and hinge plate could effectively discriminate among them. Thirty specimens of each species were sampled, and a total of 25 variables were established and utilized as input data to perform a discriminant analysis. The percentage of correctly classified cases was never less than 80%. The hinge plate variables were always relevant, and the most important one was the width of the posterior hinge plate. On the other hand, shell shape variables, when present, were secondary. Considering that the variation in the shell ofYoldiellaspecies is subtle, and also the findings of this study, we can state that the hinge plate morphometry has good potential to improve species discrimination.
“…Even with the increasing number of reports on deep-sea mollusks off Brazil (e.g., Domaneschi & Lopes 1990, Caetano et al 2006, Oliveira & Absalão 2007, 2008, 2010a, b, Simone & Cunha 2008a, b, Passos & Birman 2009, Absalão 2009, with the exception of the genus Yoldiella Verrill & Bush, 1897 (Benaim 2010, Benaim & Absalão 2011, the protobranchs remain very poorly known.…”
As a part of the Environmental Characterization of the Campos Basin project, we obtained samples from the continental slope benthos. As a consequence, specimens of Tindariopsis aeolata (Dall, 1889) and Tindariopsis agathida (Dall, 1889) were found. These species show prodissoconch surface sculpture patterns that were never seen for species of Tindariopsis. The presence of this kind of sculpture in the type species of the genus, T. agathida, adds diagnostic characters to the genus. T. agathida and T. aeolata are typical from the Caribbean Realm (Guyana and Tobago). This is the first record of T. aeolata in the southernmost area of the Atlantic Ocean, and also the shallowest record (1000 m) for this species. With this finding of specimens from the Bacia de Campos, the distribution of T. agathida can now be extended in the Brazilian coast from 7° to 22° S.
A curatorial revision of the type specimens deposited in the Mollusca Collection of the Museu Nacional / UFRJ, Rio de Janeiro, Brazil (MNRJ) revealed the existence of 518 lots of type specimens (holotypes, neotypes, syntypes and paratypes) for 285 names of molluscan taxa from 88 families, including 247 gastropods, 30 bivalves, three cephalopods and five scaphopods. A total of 106 holotypes and one neotype are deposited in the MNRJ. Type material for ten nominal taxa described as being deposited in the MNRJ was not located; the probable reasons are discussed. Some previously published erroneous information about types in the MNRJ is rectified. A total of 37 type specimens are illustrated.
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