Abstract
Correct identification of species is required to assess and understand the biodiversity of an ecosystem. In the deep sea, however, this is only possible to a limited extent, as a large part of the fauna is undescribed and the identification keys for most taxa are inadequate or missing. With the progressive impact of climate change and anthropogenic activities on deep-sea ecosystems, it is imperative to define reliable methods for robust species identification. In this study, different techniques for the identification of deep-sea species are tested, including a combination of morphological, molecular (DNA barcoding, and proteomic fingerprinting), biogeographical and ecological modeling approaches. These are applied to a family of isopods, the Haploniscidae, from deep waters around Iceland. The construction of interactive identification keys based on the DELTA format (DEscription Language for TAxonomy) were a major pillar of this study, the evaluation of which was underpinned by the application of the supplementary methods. Overall, interactive keys have been very reliable in identifying species within the Haploniscidae. Especially in a deep-sea context, these types of keys could become established because they are easy to adapt and flexible enough to accommodate newly described species. Remarkably, in this study, the interactive key enabled identification of a supposedly new species within the Haploniscidae that was later verified using both molecular genetic – and proteomic methods. However, these keys are limited given that they are based on purely morphological characteristics, including where species with strong ontogenetic or sexual dimorphism occur as both genders are not always described. In this case, integrative taxonomy is the method of choice and the combination presented here has been shown to be very promising for correct identification of deep-sea isopods.
Highlights
Species determination is the first step in conducting almost any kind of biological research
Generic Level – Haploniscidae To distinguish between the three haploniscid genera that are distributed around Iceland, two determination characters were utilized in the Interactive key (Figure 2) the articles five and six of the second antenna show a visible suture only in the genus Antennuloniscus
The species can be categorized into four different body shapes: (1) a slightly convex body shape (H. aduncus, H. bicuspis, H. borealis, H. hamatus and H. spinifer); (2) a rather straight body shape (H. angustus and H. astraphes B); (3) a plate-shaped body (H. ampliatus); and lastly (4) a fish-like body shape (H. foresti)
Summary
Species determination is the first step in conducting almost any kind of biological research. Species delimitation describes the process by which species boundaries are identified and defined involving the identification of (known) species as well as of species new to science (e.g., Wiens et al, 2007). Morphological identifications are limited by the high rate of new species discoveries (Brandt et al, 2007), combined with a high diversity and typically low densities of deep-sea communities. The latter in turn imposes restrictions on the evaluation of intra- and interspecific variations (e.g., Brandt et al, 2007; Lim et al, 2012). Intraspecific morphological variability, including ontogenetic variation, polymorphism, or sexual dimorphism, poses a challenge to species assignment based on morphological characters alone (Raupach and Wägele, 2006; Riehl et al, 2012; Zaharias et al, 2020; Paulus et al, 2021)
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