Morphometric analysis of two sympatric species ofPerinereis(Annelida: Nereididae) from the Brazilian coast

Abstract

Species definition is not an easy task, when considering the more than 27 known species concepts. Among them, the morphospecies concept has been one of the most applied since it is based on the use of observable morphological features. Morphometry has been used to delimitate morphospecies or similar taxa complementing the morphological observations and contributing to clarify taxonomic problems. Specimens from the sympatric species Perinereis anderssoni and Perinereis ponteni, collected from the north-eastern to southern coast of Brazil and considered synonymous by some authors, were compared through morphometric analyses for the evaluation of their taxonomic status. Morphometric analysis indicates that notopodial cirri lengths in the median and posterior regions on the body clearly allowed differentiation between the two species. Our results indicate that the number and arrangement of paragnaths demonstrate a pattern of variation that effectively differs and could be used to discriminate these two Perinereis species. This distinction was confirmed by the restricted among-population variability within each species, even when populations that are geographically very distant from each other were considered.

Does polyxenous symbiosis promote sympatric divergence? A morphometric and phylogeographic approach based on Oxydromus okupa (Annelida, Polychaeta, Hesionidae)

“…Our study reveals a similar morphometric difference at the inter-population level in O. okupa. In fact, these differences are even higher than those previously reported for most sibling species described on the basis of morphometry (e.g., Coutinho et al, 2015;Ford & Hutchings, 2005). However, molecular data (Fst, K2P distance and haplotype network and tree) support that the divergence observed among the Iberian populations appears to be restricted to a local level.…”

“…During the last two decades, different morphometric approaches attempted to discriminate species boundaries in polychaete cryptic and pseudo-cryptic species complexes (e.g., Omena & Amaral, 2001;Ford & Hutchings, 2005;Garraffoni et al, 2006;Lattig et al, 2007;Hernández-Alcántara & Solís-Weiss, 2014;Coutinho et al, 2015;Martin et al, 2017). However, none of them used a combination of morphometrics and genetics to evaluate differentiation levels between populations under different sources of variation, including host-symbiont relationships, a perspective that falls within the framework of integrative taxonomy (Will et al, 2005;Padial et al, 2010;Giribet, 2015;Martin et al, 2017).…”

Another brick in the wall: population dynamics of a symbiotic species of Oxydromus (Annelida, Hesionidae), described as new based on morphometry

“…Among polychaetes, many taxonomically robust morphological characters may be defined by measurements and/or proportions, some of them being size-dependent (Ben-Eliahu, 1987;Fauchald, 1991;Sigvaldadóttir and Mackie, 1993). This approach has been used independently of molecular analyses to successfully resolve the taxonomy of several sibling species complexes, often leading to the description of new species (Orrhage and Sundberg, 1990;Fauchald, 1991;Blake, 2000;Martin et al, 2003Martin et al, , 2006Martin et al, , 2009Ford and Hutchings, 2005;Garraffoni and de Garcia Camargo, 2006;Glasby and Glasby, 2006;Lattig et al, 2007;Hernández-Alcántara and Solís-Weiss, 2014;Coutinho et al, 2015). However, Ford and Hutchings (2005) were the first to consider the use of the statistical dissimilarities derived from the SIMPER routine of the PRIMER software (Clarke and Warwick, 2001;Clarke and Gorley, 2006), based on a matrix of morphometric measurements, as a robust support to distinguish between morphologically close species.…”

Molecular and morphometric analyses identify new lineages within a large Eumida (Annelida) species complex

“…Martin, Meca, Gil, Drake, and Nygren () were able to separate and delineate two distinct lineages from the symbiotic species Oxydromus humesi (Pettibone, 1961) (family Hesionidae) corresponding to Congolese and Iberian populations based on morphometric information alone. Other studies applied similar protocols in a variety of different polychaete groups (Coutinho, Paiva, & Santos, ; Ford & Hutchings, ; Lattig, San Martín, & Martin, ; Meca, Drake, & Martin, ). It is also effective in other taxonomic groups such as amphipods (Bastos‐Pereira & Ferreira, ; García‐Dávila, Magalhães, & Guerrero, ) or isopods (KamilarI & Sfenthourakis, ).…”