Genetic evidence and new morphometric data as essential tools to identify the Patagonian seahorse Hippocampus patagonicus (Pisces, Syngnathidae)

Abstract

A genetic study to support morphometric analyses was used to improve the description and validate the Patagonian seahorse Hippocampus patagonicus (Syngnathidae) on the basis of a large number of specimens collected in the type locality (San Antonio Bay, Patagonia, Argentina). DNA sequence data (from the cytochrome b region of the mitochondrial genome) were used to differentiate this species from its relatives cited for the west Atlantic Ocean. Both phylogenetic and genetic distance analyses supported the hypothesis that H. patagonicus is a species clearly differentiated from others, in agreement with morphometric studies. Hippocampus patagonicus can be distinguished from Hippocampus erectus by the combination of the following morphometric characteristics: (1) in both sexes and all sizes of H. patagonicus, the snout length is always less than the postorbital length, whereas the snout length of H. erectus is not shorter than the postorbital length in the largest specimens; (2) in both sexes of H. patagonicus, the trunk length:total length (LTr :LT ) is lower than in H. erectus (in female H. patagonicus: 0·27-0·39, H. erectus: 0·36-0·40 and in male H. patagonicus: 0·24-0·34, H. erectus: 0·33-0·43) and (3) in both sexes, tail length:total length (LTa :LT ) in H. patagonicus is larger than in H. erectus (0·61-0·78 v. 0·54-0·64).

New records of Hippocampus patagonicus Piacentino & Luzzatto, 2004 (Teleostei: Syngnathidae) from the coast of Paraná, southern Brazil

“…After capture, individuals were fixed in 70% ethanol and deposited in the fish collection of the Capão da Imbuia Natural History Museum (MHNCI 12651). González et al (2014) and Silveira et al (2014) (Figure 2), and counts and measurements were consistent with those reported by these authors ( Table 2). Most of the characters provided by Piacentino and Luzzatto (2004) Silveira et al (2014) and González et al (2014).…”

“…González et al (2014) and Silveira et al (2014) (Figure 2), and counts and measurements were consistent with those reported by these authors ( Table 2). Most of the characters provided by Piacentino and Luzzatto (2004) Silveira et al (2014) and González et al (2014). The seahorse H. patagonicus seems to have a limited and uneven distribution in Brazil, known only from a few records from the states of Pernambuco, Rio de Janeiro, São Paulo, Paraná, Santa Catarina and Rio Grande do Sul (Anderson et al 2015, Silveira et al 2014; present study).…”

“…For instance, the correlation between the distribution of this species and coastal preservation status can be assessed to provide useful information for conservation tactics in order to formulate any plan to conserve seahorse's species in Brazil. Piacentino and Luzzatto (2004), Silveira et al (2014), González et al (2014) …”

“…To identify the specimens, morphological characters, counts and measurements were taken following Piacentino and Luzzatto (2004), Lourie et al (2004), González et al (2014) and Silveira et al (2014). Measurements to the nearest 0.01 mm were made using a digital caliper.…”

“…Its distribution seems to be restricted to the coasts of Argentina and Brazil (Piacentino and Luzzatto 2004;Boehm et al 2013;González et al 2014;Silveira et al 2014), and this the southernmost occurring species of its genus in the Southwestern Atlantic Ocean. Previous records of H. patagonicus in Brazil were provided by Boehm et al (2013), Silveira et al (2014) and Anderson et al (2015).…”