Morphological and molecular characterization of a new species of Atlantic stalked barnacle (Scalpelliformes: Pollicipedidae) from the Cape Verde Islands

Abstract

The taxonomy of pedunculate cirripedes belonging to the genus Pollicipes has essentially remained unchanged since Charles Darwin described them in his exhaustive work on the Cirripedia. This genus includes three species of stalked barnacles: Pollicipes pollicipes in the north-eastern Atlantic, P. polymerus in the north-eastern Pacific and P. elegans in the central-eastern Pacific. However, a population genetics analysis of P. pollicipes suggested the presence of a putative cryptic species collected from the Cape Verde Islands in the central-eastern Atlantic. This study examines the morphology of these genetically divergent specimens and compares them with that of representative Atlantic samples of the biogeographically closely related P. pollicipes and with the poorly described P. elegans. Molecular data, including mitochondrial COX1 and nuclear ribosomal interspaces sequences, were obtained for all species of the genus Pollicipes. Morphological distinctiveness, diagnostic characters, congruent divergence level and monophyletic clustering, at both nuclear and mitochondrial loci support the taxonomic status of this new species, Pollicipes darwini.

Phylogeography of a Marine Insular Endemic in the Atlantic Macaronesia: The Azorean Barnacle, Megabalanus azoricus (Pilsbry, 1916)

“…The concept of a Macaronesian biogeographic entity has been challenged because of its flora, for example, the divergent phytogeographic affinities of the Cabo Verde pteriodophytes [ 29 ]. Present data and other phylogeographic analyses of marine invertebrates suggest a similar divergent pattern [ 23 , 24 , 76 , 92 ] modified by life cycle, vagility, behavior, and ecology. Further study is necessary to evaluate the phylogeographic hypothesis on a generalized marine pattern defined by the Cabo Verde divergence within a Macaronesian sensu lato biogeographic unit or with respect to the Macaronesian sensu stricto , originating from and sustained by paleoclimatology and oceanography, respectively.…”

“…The intraspecific variability, calculated from the COX1 partition data set ( N = 54, length = 658 bp), was 0.0036 (S.D. = 0.0013), which is in the range of other intraspecific barnacle values: 0.006–0.011 in Pollicipes species [ 24 ] and 0.022 in Balanus glandula [ 62 ].…”

“…In contrast, the Cabo Verde archipelago is under a different climate and oceanographic regime with a composite biogeographic character, having both Caribbean and Atlantic-Mediterranean affinities regarding the marine biota [ 14 ]. As a result, this biogeographic divergence is to varying degrees reflected in genetic discontinuities observed in related and other marine invertebrates [ 23 , 24 , 76 ]. The observed isolation of Cabo Verde is supported by favorable contemporary hydrographic dynamics influencing planktotrophic larval dispersion [ 23 ].…”

“…Similar work contributed to new species descriptions in the Tretaclita squamosa complex in Asia [ 21 , 22 ]. Analysis of genetic diversity through the East Atlantic distribution range of Pollicipes pollicipes detected a distinctive, monophyletic population in Cabo Verde [ 23 ], which was subsequently described as a new species [ 24 ]. Phylogeographical inferences include the relationship between local oceanography and clade structure in the morphologically homogeneous acorn barnacle, Chthamalus malayensis , along the Indo-West Pacific [ 25 ].…”