Phylogeography of the marine interstitial nemertean Ototyphlonemertes parmula (Nemertea, Hoplonemertea) reveals cryptic diversity and high dispersal potential

Abstract

We conducted a phylogeographic study of the meiofaunal nemertean Ototyphlonemertes parmula, an apparent species complex from the littoral zone of coarsegrained beaches, using a 494-bp fragment of the mitochondrial cytochrome oxidase 3 gene (cox3). Six populations from the Gulf and Atlantic coasts of Florida, two from New England, and one from the Caribbean were sampled in March and August 2005. Three major lineages were identified, separated by cox3 sequence divergence of 16-18%, with partially overlapping ranges. Tests for hybridization using ISSR markers detected nuclear gene exchange within but not between the major mitochondrial lineages, indicating the presence of cryptic species. One lineage dominating the Atlantic coast of Florida shows no evidence of geographic structuring. Another lineage shows a phylogenetic break between the Atlantic and Gulf coasts, suggesting that Communicated by C. Riginos.Electronic supplementary material The online version of this article

Barcoding against a paradox? Combined molecular species delineations reveal multiple cryptic lineages in elusive meiofaunal sea slugs

“…5000 km linear distance). The same scenario of long-distance dispersal on the one hand and clear spatial structuring on the other have also been recorded in other meiofaunal taxa; e.g., Nematoda [81], Nemertea [29,82] and Rotifera [45]. The widespread MOTUs in the present study span predicted barriers of gene flow for minute meiofaunal taxa, such as the Amazon freshwater and sediment plume or deep-sea regions between islands.…”

At least some meiofaunal species are not everywhere. Indication of geographic, ecological and geological barriers affecting the dispersion of species of Ototyphlonemertes (Nemertea, Hoplonemertea)

“…Each of the 488 specimens considered in this study was assigned at time of collection to one of the following morphological species: O. americana (three individuals), O. correae (9), O. duplex (138), O. erneba (39), O. evelinae (5), O. parmula (synonymized with O. fila by Tulchinsky et al . ) (55), O. lactea (108), O. macintoshi (63), O. pallida (14), O. pellucida (1) and O. santacruzensis (53) (Table S1). Most morphological species were found to be cosmopolitan, namely collected from at least two biogeographical areas, with the exception of O. correae whose nine individuals were all from the northeast Atlantic (England and Sweden), and O. evelinae and O. pellucida , represented, respectively, by only five and one individual all collected from Florida (Table S1).…”

“…; Tulchinsky et al . ; Leasi & Norenburg ). These studies, however, (i) could not provide a broader view of geographic distribution and how that is affected by natural barriers.…”

The Necessity of DNA Taxonomy to Reveal Cryptic Diversity and Spatial Distribution of Meiofauna, with a Focus on Nemertea

“…This might be expected, since cryptic lineages were already suggested within all these genera [24], [25], [39], [44], [45], [56]. For instance, the O. lactea morphotype was already suggested to be a putative complex of cryptic species by Andrade et al [24], whereas Tulchinsky et al [25] suggested the presence of several cryptic lineages within O. parmula . The genus Ototyphlonemertes does not possess unambiguous diagnostic morphological traits across different species, which is why Envall & Norenburg [38] reduced the known species and about 75 additional regional varieties to six so-called phylomorphs.…”