Haminoea elegans (Gray, 1825)

Turani, Martina, Valdés, Ángel & Malaquias, Manuel António E., 2024, Molecular phylogeny of the marine snail genus Haminoea (Gastropoda, Cephalaspidea): A framework to study marine diversity and speciation, Zoologica Scripta 53 (1), pp. 52-77 : 70-71

4.2 | The Haminoea elegans complex

Haminoea elegans is characterized by having whitish translucent spiralled shells and it has been regarded as widely distributed in the Western Atlantic throughout the Gulf of Mexico and the Caribbean Sea southwards to Brazil ( Valdés et al., 2006) with records in West Africa between the Gulf of Guinea and Angola ( Bernard, 1984; Martínez & Ortea, 1997; Rolán & Ryall, 1999). However, the attribution of the name ‘ elegans ’ to this tropical amphi-Atlantic species stems certainly from a misidentification perpetuated in the literature over time. The name H. elegans was introduced by Gray (1825) based on spiralled shells from the British Isles and the Mediterranean Sea, and the name is most certainly a junior synonym of Haminoea navicula , the only European species with a deeply spiralled shell ( Malaquias & Cervera, 2006).

Our results showed the existence of cryptic diversity in this ‘species’ with specimens provisionally ascribed by us to H. elegans splitting in four (or five) clades of possible species status (groups 7, 17–19; Figure 1, Appendices S2, S9, S10 and S13). Representatives of groups 17, 18 and 19 clustered together with maximum support, whereas group 7 branched off elsewhere in the tree (Figure 1, Appendix S2, S9 and S10).

If, in contrast, our results unequivocally support group 7 as a good species, they are not conclusive about the eventual status of group 17, with one of the species delimitation analysis (bPTP), suggesting the possible occurrence of two lineages in this group. However, none of the single gene and combined analyses retrieved reciprocal monophyly between sub-clades within group 17. When present, the sub-clades are not statistically supported (Appendices S3–S10).

The results are also not entirely conclusive about the conspecificity of groups 18 and 19 (see Section 3 – theme 3.2). Groups 18 and 19 are the only two in the complex with a genetic distance between themselves below 10%, but still moderately high (= 7.5%). Moreover, in the haplotype network analysis, they were separated by 36 substitutions, the largest number of substitutions between putative conspecific groups among all our haplotype network analyses (Figure 4).

There are several names available in the literature that could be regarded as previous attempts to describe the shells variability in the H. elegans complex (e.g. H. guildingii ( Swainson, 1840) [shells globose with visible spiral striae], H. petitii ( d'Orbigny, 1841) [shells lacking or with inconspicuous spiral striae], H. succinea ( Conrad, 1846) [shells cylindrical with tightly arranged spiral striae], H. taylorae ( Petuch, 1987) [shells globose with numerous fine spiral striae]). These names have been in part considered synonyms of H. elegans (MolluscaBase, 2022; Valdés et al., 2006) or hardly used in scientific literature, but our results show the need to carefully re-evaluate the status of these names since some of them may apply to lineages revealed by our analyses.

The only study that provided a comparative analysis of the various types of shells of ‘ H. elegans ’ in the Western Atlantic was by Redfern (2013: 266–268). This author recognized five different types of whitish shells that could be associated with H. elegans ; four with spiral striae and one apparently smooth. One of these forms was named by Redfern (2013) Haminoea elegans proper and the other four Haminoea A, B, C and D. According to the author, Haminoea elegans and Haminoea sp. A are characterized by globose-quadrate opaque shells with wavy-spiral striae and a partially concealed involute spire; Haminoea sp. B by a more oval translucent shell, with numerous tightly arranged spiral striae and a spire concealed by a callus; Haminoea sp. C by a globose opaque smooth shell and a spire concealed by a callus; Haminoea sp. D by cylindrical translucent shells, with lightly impressed spiral striae and a spire concealed by a callus.

Here we provide for the first time a phylogenetic framework to properly explore the diversity of the Haminoea ‘ elegans ’ species-complex. Yet confirming whether our four (or five) candidate species correspond to the shell types identified by Redfern (2013) and are compatible with the names available in the literature, requires additional taxonomic work based on detailed analyses of conchological and morpho-anatomical characters.