Teo Delić

The importance of naming cryptic species and the conservation of endemic subterranean amphipods.

Molecular taxonomy often uncovers cryptic species, reminding us that taxonomic incompleteness is even more severe than previous thought. The importance of cryptic species for conservation is poorly understood. Although some cryptic species may be seriously threatened or otherwise important, they are rarely included in conservation programs as most of them remain undescribed. We analysed the importance of cryptic species in conservation by scrutinizing the South European cryptic complex of the subterranean amphipod Niphargus stygius sensu lato. Using uni- and multilocus delineation methods we show that it consists of 15 parapatric and sympatric species, which we describe using molecular diagnoses. The new species are not mere “taxonomic inflation” as they originate from several distinct branches within the genus and coexist with no evidence of lineage sharing. They are as evolutionarily distinct as average nominal species of the same genus. Ignoring these cryptic species will underestimate the number of subterranean endemics in Slovenia by 12 and in Croatia by four species, although alpha diversity of single caves remains unchanged. The new taxonomy renders national Red Lists largely obsolete, as they list mostly large-ranged species but omit critically endangered single-site endemics. Formal naming of cryptic species is critical for them to be included in conservation policies and faunal listings.

Do cryptic species matter in macroecology? Sequencing European groundwater crustaceans yields smaller ranges but does not challenge biodiversity determinants

Ecologists increasingly rely on molecular delimitation methods (MMs) to identify species boundaries, thereby potentially increasing the number of putative species because of the presence of morphologically cryptic species. It has been argued that cryptic species could challenge our understanding of what determine large-scale biodiversity patterns which have traditionally been documented from morphology alone. Here, we used morphology and three MMs to derive four different sets of putative species among the European groundwater crustaceans. Then, we used regression models to compare the relative importance of spatial heterogeneity, productivity and historical climates, in shaping species richness and range size patterns across sets of putative species. We tested three predictions. First, MMs would yield many more putative species than morphology because groundwater is a constraining environment allowing little morphological changes. Second, for species richness, MMs would increase the importance of spatial heterogeneity because cryptic species are more likely along physical barriers separating ecologically similar regions than along resource gradients promoting ecologically-based divergent selection. Third, for range size, MMs would increase the importance of historical climates because of reduced and asymmetrical fragmentation of large morphological species ranges at northern latitudes. MMs yielded twice more putative species than morphology and decreased by 10-fold the average species range size. Yet, MMs strengthened the mid-latitude ridge of high species richness and the Rapoport effect of increasing range size at higher latitudes. Species richness predictors did not vary between morphology and MMs but the latter increased the proportion of variance in range size explained by historical climates. These findings demonstrate that our knowledge of groundwater biodiversity determinants is robust to overlooked cryptic species because the latter are homogeneously distributed along environmental gradients. Yet, our findings call for incorporating multiple species delimitation methods into the analysis of large-scale biodiversity patterns across a range of taxa and ecosystems.

The giant cryptic amphipod species of the subterranean genus Niphargus (Crustacea, Amphipoda)

Amphipods from the genus Niphargus represent an important part of the Western Palearctic subterranean fauna. The genus is morphologically diverse, comprising several distinct ecomorphs bound to microhabitats in the subterranean environment. The most impressive among them are “lake giants,” a series of massive, large‐bodied species. These range from morphologically distinct to morphologically cryptic taxa. We analysed the taxonomic structure of the Niphargus arbiter–Niphargus salonitanus species complex, belonging to “lake giants” from the Dinaric Karst (West Balkans), and assessed their phylogenetic, morphological and ecological diversity. Multilocus phylogeny suggested that the complex is monophyletic and nested within other cave lake ecomorphs. Unilocus and multilocus coalescence species delimitations indicated that the complex totals nine species. These species substantially overlap in morphology and cannot be unambiguously told apart without the use of molecular markers. An analysis of splitting events within a palaeogeological context, and modelling of environmental characteristics on the phylogeny unveiled a complex history of diversification. Part of this diversification might have been influenced by ecological divergence along the altitudinal gradient reaching from the Adriatic coast to inland Dinaric mountain chains and Poljes. Other splits coincide with the marine regression–transgression cycles during Pliocene. We describe Niphargus alpheus sp. n., Niphargus anchialinus sp. n., Niphargus antipodes sp. n., Niphargus arethusa sp. n., Niphargus doli sp. n., Niphargus fjakae sp. n. and Niphargus pincinovae sp. n., and by doing so hope to prompt their further research.

Molecular phylogeny of Niphargus boskovici (Crustacea: Amphipoda) reveals a new species from epikarst

We describe a new species of an amphipod Niphargus zagorae sp. n. and redescribe its nearest relative and morphologically similar species N. boskovici S. Karaman, 1952. We present the geographic distributions of both species, morphological diagnoses and infer their phylogenetic position within the genus based on COI, 28S and H3 markers.

Description of a new species of Niphargus (Crustacea: Amphipoda: Niphargidae): the first record of a lake ecomorph in the Carpathian Mountains.

We describe and phylogenetically characterize a new species Niphargus mirocensis from Mt. Miroč, eastern Serbia. This species shows distinct morphology typical for a lake ecomorph of niphargid amphipod, i.e. large and stout body, elongated appendages and raptorial gnathopods and presents the first record of this ecomorph in Carpathian Mountains. Phylogenetic analyses based on Cytochrome Oxidase Subunit 1 gene (COI), Histone (H3) and 28S rRNA (28S) suggests that species is nested within a clade of lake ecomorphs spread in Italy and Central Dinaric Region. The new finding is geographic extension of clades range, the species of which are generally narrow endemics.

Setting a morphological framework for the genus Verhoeffiella (Collembola, Entomobryidae) for describing new troglomorphic species from the Dinaric karst (Western Balkans)

Abstract. Recent research of cave Collembola in Dinaric karst resulted in discovery of high regional diversification of the genus Verhoeffiella Absolon, 1900. The most striking feature of Verhoeffiella species is the high number of troglomorphic traits, which makes this genus a good model for studying morphological diversification and adaptation in subterranean environments. We explore the expression of various morphological modifications assumed to be linked to subterranean life, through detailed descriptions of four new species and redescription of two species including the type species of the genus. Species delimitations are confirmed by single locus (cytochrome c oxidase I) tree-based (Poisson tree processes) and distance-based (automatic barcode gap discovery) species delimitation approaches, which gave identical results. Morphological changes classically considered as adaptive for cave life and new, potentially troglomorphic characters for Collembola are discussed. For several of these characters, high morphological diversity between species and large decoupling in the development of different traits within species are recorded. Such a decoupling is also illustrated in the finding of two cases of Verhoeffiella species pairs at different levels of troglomorphy living in syntopy. We further provide several new differential characters of specific and possibly generic or supra-generic importance and describe for the first time among Collembola an original ‘distal organ’ on Ant. IV.

Locomotion of Niphargus amphipods from cave lakes and streams

Locomotion is a complex trait directly linked to different fitness components such as foraging, mate-finding, and escaping from predators. In a food-limited subterranean environment a strong selection for an energetically optimal strategy of locomotion is expected and should lead to different strategies among closely related species adapted to different microhabitats. Due to its taxonomic and ecological diversity, the amphipod genus Niphargus is an ideal model system for studying locomotion strategies of species affiliated with different subterranean aquatic microhabitats. Such species differ from each other morphologically, and we predicted that they also evolved alternative strategies of locomotion. In this study, we examined three species from cave lakes and five species from cave streams or springs. After collection all species were first acclimated in a cave laboratory. Then, we video-recorded behaviour in a rectangular open-field arena of approximately 10 individuals per species. A single individual at a time was recorded under red light for 20 minutes. Videos were used to construct ethograms of distinct locomotor behaviours such as swimming, crawling, and walking. A video-tracking analysis was performed to extract variables like total path covered, time spent moving, average and maximal speed. Individuals were euthanized and measured for several morphological traits likely related to locomotion. Additionally, we measured activities of enzymes acetylcholinesterase and glutathione S-transferase, which are likely related to animals’ ‡ ‡ § ‡ ‡ ‡ ‡