Browsing by Author "Diaz-Santana-Iturrios, Mariana"

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    Description and discrimination of sagittae otoliths of two sympatric labrisomid blennies Auchenionchus crinitus and Auchenionchus microcirrhis using morphometric analyses
    (2021) Cerda, Jose Miguel; Palacios-Fuentes, Pamela; Diaz-Santana-Iturrios, Mariana; Ojeda, F. Patricio
    Auchenionchus crinitus and Auchenionchus microcirrhis share their distributional area along the Chilean coast. These labrisomid blennies are difficult to recognize based on the attributes described in taxonomic keys, which consist of overlapped or non-informative morphological and meristic characteristics of body parts. Sagittae otolith shape is useful for species determination; thus, the aim of our study was to evaluate the discriminant power of sagittae otoliths through analyses of shape indices and geometric morphometrics, and to describe the sagittae otolith shape of the two fish species. Four linear measurements (length, width, area and perimeter) of sagittae otoliths were considered to calculate the shape indices. Inter-specific differences were assessed by MannWhitney U tests for each index, and no significant differences between species were found (U = 181.5-256; p > 0.05). Based on these results, the shape indices evaluated here must not be employed for species of the genus Auchenionchus. A total of 72 landmarks contouring sagittae otoliths were considered for the geometric morphometric analysis, where the least-squares Procrustes method was followed to obtain a consensus coordinate matrix. The sagittae otolith was morphologically distinctive for each species, A. crinitus shows a wide and curved rostrum compared with A. microcirrhis, where this feature is more angled and elongated. Similarly, the posterior edge in the otolith of A. crinitus is wide in curvature, while this portion is angled in curvature in A. microcirrhis. The vertex between rostrum and anti-rostrum forms a cordiform shape in the sagittae otolith of both species, although in A. crinitus this characteristic is more prominent. A Principal Component Analysis and a Discriminant Function Analysis using the consensus coordinate matrix allowed us to confirm the differences between species according to sagittae otolith shape. Our study constitutes the first assessment of sagittae otolith shape via geometric morphometrics in the family Labrisomidae.
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    NORTHEASTERN PACIFIC OCTOPUS BEAK SHAPE FOR SPECIES-LEVEL DETECTION
    (2022) Diaz-Santana-Iturrios, Mariana; Zepeda-Benitez, Viridiana; Pacheco-Ovando, Renata; Cornejo, Claudio F.; Miguel Cerda, Jose; Augusto Salinas-Zavala, Cesar; Granados-Amores, Jasmin
    Cephalopods have upper and lower chitinous beaks, and their shape can be used to identify species. However, the morphological attributes of beaks are commonly obtained from sources that contain little information on shape, compromising the determination of taxa. Thus, in this study, we used geometric morphometrics to analyze inter-specific differences in beak shape of six octopus species from the northeastern Pacific. We found evidence of species-level discrimination according to upper and lower beak shape. In addition, we provided a detailed description of these chitinous structures for each species, and we developed a key to identify the species based on upper and lower beak shape. The inter-specific morphological variation of beaks of the octopuses evaluated in our study could be the result of adaptive processes related to habitat and feeding habits. The information generated in our study can be used for identification of six octopus species from the northeastern Pacific based on upper and lower beak shape.