920
Journal of Paleontology 91(5):919–932
synapomorphy of the genus Parabolinella (excluded P.? triarthroides) (Monti and Confalonieri, 2013). The aim of this study is to solve the generic assignment of
this species, performing a revision of the type material and a morphometric analysis of P. triarthroides, Parabolinella,and Bienvillia specimens. The original matrix used in a previous phylogenetic analysis (Monti and Confalonieri, 2013) was reviewed in light of the revision of the type material and was enlarged to include more species of Bienvillia. Continuous characters were coded in different ways in order to compare how they could affect the results. Because the variables used in the morphometric analysis were also treated as characters in the phylogenetic analysis, both results were compared and the behavior of these variables was analyzed. This study points to the importance of combining different methodological approaches with exhaustive qualitative analyses, which are necessary to recognizemorphological traits and to solve systematic problems.
Materials and methods
Materials.—Studied specimens correspond to previously collected material from Ordovician outcrops in the Cordillera Oriental Argentina, at Purmamarca region and Quebrada Moya, Jujuy Province (Monti et al., 2016). Also more than 250 speci- mens from the “Harrington and Leanza Collection” (Harrington and Leanza, 1957) were reviewed (Supplementary dataset 1). These samples consist of specimens from Cambro-Ordovician units exposed at different localities in the Cordillera Oriental: quebradas Huasamayo, Rupasca, and San Gregorio (Alfarcito area); Bocoyá River and Nazareno River (Iruya Region); Quebrada Colorada de Fundición and Santa Victoria River (Santa Victoria region); Negrito River (tributary of Santa Cruz River), La Caldera region; Reyes River, Cumbre de Castillejo region; Quebrada de Coquena (Purmamarca region); and Quebrada del Barranco (Pascha area). We measured 136 specimens (ingroup) and 6 (outgroup)
to construct the input matrix for the phylogenetic analysis (Supplementary dataset 1). From these, 90 more-complete specimens were included in the morphometric analysis, given that the method does not allow the existence of missing entries (Supplementary dataset 1, 2). The sample for the morphometric analysis includes 28 specimens of Bienvillia: B. parchaensis (Harrington and Leanza, 1957) (5); B. rectifrons (Harrington, 1938) (7); B. tetragonalis (Harrington, 1938) (9), B. jana Waisfeld and Vaccari, 2006 (5); and B. kichka Waisfeld and Vaccari, 2006 (2). The sample for morphometric analysis also includes 57 specimens of Parabolinella: P. clarisae Monti, Benítez, and Ramírez, 2016 (28); P. pompadouris Monti, Benítez, and Ramírez, 2016 (8); P. argentinensis Kobayashi, 1935 (13); P. coelatifrons Harrington and Leanza, 1957 (6); and P. limitis Brøgger, 1882 (2) (Supplementary dataset 2). In this analysis, the types of P. triarthroides described by Harrington (1938) (CPBA 5, type and CPBA 54, paratype) and other specimens of this species from the type locality (CPBA 9; Waisfeld and Vaccari, 2003, pl. 32, figs. 15, 16) were also included. Nine additional species of Parabolinella, whose characters were analyzed and coded on the basis of published descriptions and figures (see Monti and Confalonieri, 2013) also
were added: P. jianganensis Lu and Lin, 1984; P. ocellata Lu and Lin, 1984; P. prolata Robison and Pantoja-Alor, 1968; P. tumifrons Robison and Pantoja-Alor, 1968; P. variabilis Robison and Pantoja-Alor, 1968; P. bolbifrons Fortey and Owens, 1997; P. lata Henningsmoen, 1957; P. triarthra (Callaway, 1877) Parabolinella new sp., and P. limitis) were incorporated in the cladistic analysis. All the specimens included in the analyses are holaspids and they are preserved as imprints and molds (internal and external). Most of them have suffered minor tectonic distortion. Disarticulated elements of the trilobite exoskeleton prevail, dominated by cranidia.
Morphometric analysis.—Eleven measurements fromthe above- mentioned 90 specimens corresponding to P.? triarthroides and different species of Parabolinella and Bienvillia were taken for the analyses (Table 1, Fig. 1, Supplementary dataset 2). With the aim of ordering the specimens according to the morphometric variability observed, three different Principal Component Analyses (PCA) were performed from the variance-covariance matrix: (1) using the set of logarithm transformed raw data, (2) using the logarithmof the rawdata corrected by the geometric mean (hereafter called GMD) (Mosimann size variables) (see Mosimann and James, 1979; Meachen-Samuels and Van Valkenburgh, 2009), and (3) using the logarithm of nine new variables generated from the relationship of the original ones (hereafter called RD) (Table 1). It is important to note that all of the preceding analyses were also carried out with the correlation matrices (instead of variance-covariance matrices) of the untransformed data, although they are not shown in detail because outcomes regarding the separation of both genera and the variables of importance to distinguish them were very similar to those obtained with the variance-covariance matrices of the log-transformed data (see Supplementary datasets 3, 4). The analyses were performed with the software R version 3.2.2 (R Development Core Team, 2015) using the package vegan
2.3-1 (Oksanen et al., 2015). For GMD and RD analyses, con- fidence intervals of the eigenvectors of each variable were
Table 1. Description of the variables used in each morphometric analysis. Dataset Variables
Description
GMD LPA LPF LPL LC Lgl
LOR WglE WglB WOR WPF WIG
RD Lgl/LC LOR/Lgl
Lgl/WglB LPL/Lgl
Length of the Preglabellar Area Length of the Preglabellar field Length of the Palpebral Lobes Length of the Cranidio Length of the glabella
Length of the Occipital Ring Width of the glabella (Eyes) Width of the glaballa (Base) Width of the Occipital Ring Width of the Posterior Fixinae Width of the Interocular Genae
LOR/WOR Length of the Occipital Ring/Width of the Occipital Ring
Length of the glabella/ Length of the Cranidia Length of the Occipital Ring/Length glabella
Length glabella/Width glabella (Base) Length Palebral Lobes/ Length glabella
WIG/WglE Width of the Interocular Genae/Width of the glebella (Eyes)
WPF/WOR Width of the Posterior Fixigenae/Width of the Occipital Ring
LPF/LOR Length of the Preglabellar Field/ Length of the Occipital Ring
LPF/LPA
Length of the Preglabellar Field/ Length of the Preglabellar Area
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