The tail tells the tale: taxonomy and biogeography of some Atlantic Chelidonura (Gastropoda: Cephalaspidea: Aglajidae) inferred from nuclear and mitochondrial gene data

Abstract

Several western Atlantic species of Chelidonura have been described mainly based on differences in colour pattern. Sequence data from two mitochondrial [cytochrome oxidase I (COI), 16S] genes and a nuclear [histone 3 (H3)] gene have revealed that all colour forms previously recognized from across the Caribbean, Bahamas, and Bermuda belong to the same species, Chelidonura berolina. However, several specimens from the Bahamas are genetically and morphologically distinct and are herein described as a new species, Chelidonura normani sp. nov. Externally, C. normani can only be distinguished from C. berolina by the morphology of the posterior end of the body and not by colour pattern. Both C. berolina and C. normani are genetically and morphologically distinct from the eastern Atlantic species Chelidonura africana, but the split between C. berolina and C. normani predates the split between C. berolina and C. africana. All three species differ in their protoconch morphology, which suggests different developmental modes. Furthermore, all three species display a broad variation in colour pattern, which raises questions on the biological significance of colour in this group. The reasons for the divergence between C. berolina and C. normani remain unknown but could be related to the complex geological history of the western Atlantic.

Identification guide to the heterobranch sea slugs (Mollusca: Gastropoda) from Bocas del Toro, Panama

“…From Mexico to Colombia, Cayman Islands, Cuba, Jamaica, Martinique, Puerto Rico, Bermuda, Bahamas (Valdés et al, 2006;Ornelas-Gatdula et al, 2011;Malaquias, 2014).…”

Phylogeny of the family Aglajidae (Pilsbry, 1895) (Heterobranchia: Cephalaspidea) inferred from mtDNA and nDNA

“…Currently, seven valid genera are recognized in the Aglajidae, but the number of species recognized as valid in each genus is controversial due to conflicting taxonomic interpretations. Of the seven genera Aglaja Reiner, 1807 has been determined to contain 6 species (3 studied here); Chelidonura A. Adams, 1850 is the most diverse with 24-28 species depending on the authors (see Ornelas-Gatdula et al, 2011;Ortea et al, 2012) (17 studied here); Melanochlamys Cheeseman, 1881 includes 9 species (3 studied here); Nakamigawaia Kuroda and Habe in Habe, 1961 with 2 species is the least diverse (2 included here); Navanax Pilsbry, 1895 has 5 species (4 studied here); Philinopsis Pease, 1860 contains 13-15 species depending on the authors (Ortea et al, 2012), including 14 studied here; and Odontoglaja Rudman, 1978 includes 3 species (2 studied here). Even though Noalda Iredale, 1936 was suggested to be an aglajid by Burn and Thompson (1998) specimens for molecular study were not available, and therefore it is not included in this study.…”

It’s not what it looks like: molecular data fails to substantiate morphological differences in two sea hares (Mollusca, Heterobranchia, Aplysiidae) from southern Brazil

“…I for 16S, and GTR ? I?G for H3) were determined using the Akaike information criterion (Akaike 1974) implemented in MrModelTest (Nylander 2004). Bayesian analyses were conducted using MrBayes 3.2 (Ronquist et al 2012), partitioned by gene (unlinked).…”