Clarifying the taxonomic status of the alien species Branchiomma bairdi and Branchiomma boholense (Annelida: Sabellidae) using molecular and morphological evidence

Abstract

This study was performed to analyse the genetic and morphological diversity of the sabellid annelid genus Branchiomma, with special emphasis on a taxon so far identified as Branchiomma bairdi. This species, originally described from Bermuda, has frequently been reported as an invader in the Mediterranean, the Atlantic and the Eastern Pacific, but recent observations have raised some taxonomic questions. Samples of this taxon were collected from five sites in the Mediterranean Sea, two sites in the original distribution area of B. bairdi in the Gulf of Mexico and four localities in the east Pacific and Atlantic Oceans where B. bairdi has been reported as invasive. The molecular results revealed a conspicuous genetic divergence (18.5% K2P) between the sampled Mediterranean populations and all the other ones that led to a re-evaluation of their morphological characters. The latter showed that the Mediterranean and extra-Mediterranean populations also differ in some discrete morphological and reproductive features. Consequently, the Mediterranean samples were re-designated as B. boholense, another non-indigenous species originally described from Philippines. Branchiomma bairdi and B. boholense differ in body size, development and shape of micro and macrostylodes, size of radiolar eyes and body pigmentation. Genetic diversity was high in B. boholense from the Mediterranean as well as in B. bairdi from the Gulf of Mexico, but low in B. bairdi populations outside their native range. The phylogenetic analysis revealed the presence of connections between the Mediterranean localities as well as between native and introduced B. bairdi populations that focus the attention on the Panama Canal as important passage for the introduction of the species from the Gulf of Mexico to the north-east Pacific Ocean.

Seasonal and bathymetric effects on macrofouling invertebrates’ primary succession in a mediterraenan non-indigenous species hotspot area

“…Among the taxa characterizing the endpoints, some of them, such as M. galloprovincialis, S. spallanzanii, C. lepadiformis, and S. errata, are typical of fouling communities of Mediterranean harbor and eutrophic environments, and are already known as dominant species in the fouling of the presently studied area (Gherardi & Lepore, 1974;Tursi et al, 1974;Pierri et al, 2010). By contrast in the late stage of the community, the present study confirms the structural role of some relatively recent faunistic entries for the Gulf of Taranto, such as P. magna (Longo et al, 2007) and B. boholense (Del Pasqua et al, 2018). Four different successional patterns relative to the four starting times were observed.…”

“…It is characterized by the total absence of Mytilus, which, by contrast, appear in the late succession, when the community have already reached the end point structure, and therefore the mussels fail to colonize en masse. Moreover, in the starting time of the S2 a strong recruitment of alien species, particularly P. zorritensis, needs to be highlighted, most of them being seasonal taxa which decrease significantly during the following quarters (Lezzi et al, 2018). On the contrary, Mytilus galloprovincialis appears only in T4 (April-July 2014) when the community is already structured.…”

Marine alien species in Italy: A contribution to the implementation of descriptor D2 of the marine strategy framework directive

“…While B. boholense and F. enigmaticus may have reached the Adriatic Sea unaided, the remaining invaders have probably arrived through maritime traffic (ballast water or hull fouling). Branchiomma boholense was originally described from the Philippines and introduced to the Mediterranean in 1927 (Knight-Jones et al, 1991;Del Pasqua et al, 2018); this species, previously misidentified as the Bermudian B. bairdi, is particularly abundant in confined zones and areas degraded by anthropogenic impacts (Arias et al, 2013). The casual records amount to 10 species, among which Naineris setosa, which was recorded in Brindisi (from an aquaculture farm), but the population became extinct (Blake & Giangrande, 2011); nevertheless, N. setosa was recorded in the Tyrrhenian from 2010 to 2014 (Atzori et al, 2016), where it has established permanent populations.…”

Ancient globetrotters—connectivity and putative native ranges of two cosmopolitan biofouling amphipods

“…Intra-and interspecific species distances were calculated in MEGA 7.0 based on the Kimura-two-parameter (K2P) model with pairwise deletion using the full length of 657 bp sequences; these were then used to estimate genetic divergence between taxa. The K2P model was preferred over more complex and fitting models in order to ensure comparability of the results with those of published literature and other species delimitation analyses (Del Pasqua et al, 2018).…”