Maja Zagmajster

Phototransduction and clock gene expression in the troglobiont beetle Ptomaphagus hirtus of Mammoth cave

SUMMARY Obligatory cave species exhibit dramatic trait modifications such as eye reduction, loss of pigmentation and an increase in touch receptors. As molecular studies of cave adaptation have largely concentrated on vertebrate models, it is not yet possible to probe for genetic universalities underlying cave adaptation. We have therefore begun to study the strongly cave-adapted small carrion beetle Ptomaphagus hirtus. For over 100 years, this flightless signature inhabitant of Mammoth Cave, the worlds largest known cave system, has been considered blind despite the presence of residual lens structures. By deep sequencing of the adult head transcriptome, we discovered the transcripts of all core members of the phototransduction protein machinery. Combined with the absence of transcripts of select structural photoreceptor and eye pigmentation genes, these data suggest a reduced but functional visual system in P. hirtus. This conclusion was corroborated by a negative phototactic response of P. hirtus in light/dark choice tests. We further detected the expression of the complete circadian clock gene network in P. hirtus, raising the possibility of a role of light sensation in the regulation of oscillating processes. We speculate that P. hirtus is representative of a large number of animal species with highly reduced but persisting visual capacities in the twilight zone of the subterranean realm. These can now be studied on a broad comparative scale given the efficiency of transcript discovery by next-generation sequencing.

Two new Amphipod families recorded in South America shed light on an old biogeographical enigma

The known diversity of freshwater amphipods in South America is substantially lower than on other continents. This has puzzled biologists for decades. Two hypotheses have been proposed in attempts to explain this pattern. According to the first one, the majority of amphipod lineages never dispersed across South America. The alternative hypothesis is that the recently diversified hyalellids have outcompeted and depleted the ancestral amphipod fauna. The recently discovered freshwater amphipod species Seborgia potiguar sp. nov. (Seborgidae) and Potiberaba porakuara gen. nov., sp. nov. (Mesogammaridae) from Brazil reveals the existence of two additional families of amphipods in South America. In the light of these discoveries we have analysed the amphipod faunistic structure of South America to test the above two biogeographic hypotheses. First, the number of amphipod families in South America is not as low as was thought. Falklandellididae are limited to the Falkland Islands and Chile. All other families (Ingolfiellidae, Bogidiellidae, Phreatogammaridae, Paraleptamphopidae, Pseudoingolfiellidae, Paracorpohiinae, Mesogammaridae and Seborgidae) but one (Dogielinotidae) share two properties: (1) they have a transoceanic distribution and (2) they are from subterranean waters. Since the dispersal ability of amphipods is limited, trans-oceanic disjunctions are best explained by plate tectonics, which implies their early origin, negating the first biogeographical hypothesis. These ancient families, for unknown reasons, survived only in a stable subterranean environment which can be regarded as a refuge. The only recent colonizer of the continent might be Dogielinotidae with the species-rich genus Hyalella. Although it cannot be determined whether hyallelids truly out-competed ancient amphipods, we suggest that the second hypothesis fits better to the data. Further findings of amphipods are expected in South America, especially from subterranean waters. This habitat is highly endangered in Brazil, and should be more rigorously protected. http://www.zoobank.org/urn:lsid:zoobank.org:pub:CBE21C1E-4748-4237-9EAD-FBD240A7D501

First record of Bathynellacea (Crustacea, Syncarida, Parabathynellidae) in China: a new genus

A new genus and species of Syncarida, family Parabathynellidae, is described from China. Sinobathynella decamera n. g. n. sp. is one of the worlds largest known Bathynellacea species (3.7 mm) and displays several exclusive characters: 10 segments in the antennule, exopod of thoracopods 3–7 with 10 segments and thoracopod 8 female with two spines and two long setae. The new species also has a unique combination of characters: an antennule with 10 segments; antenna with six segments; pars incisiva of the mandible with three teeth and pars molaris with 14 teeth; distal endite of maxillule with seven claws; epipods present in thoracopods 3–7; an absence of pleopods; endopod of thoracopod 8 male with two long setae; 20 spines on the sympod, and three or four spines on the endopod of the uropod. This is the first time that the Bathynellacea (family Parabathynellidae) has been found in China, extending the range of distribution of this taxon in Asia.

The first phylogenetic analysis of Palpigradi (Arachnida)—the most enigmatic arthropod order

Abstract. Palpigradi are a poorly understood group of delicate arachnids, often found in caves or other subterranean habitats. Concomitantly, they have been neglected from a phylogenetic point of view. Here we present the first molecular phylogeny of palpigrades based on specimens collected in different subterranean habitats, both endogean (soil) and hypogean (caves), from Australia, Africa, Europe, South America and North America. Analyses of two nuclear ribosomal genes and COI under an array of methods and homology schemes found monophyly of Palpigradi, Eukoeneniidae and a division of Eukoeneniidae into four main clades, three of which include samples from multiple continents. This supports either ancient vicariance or long-range dispersal, two alternatives we cannot distinguish with the data at hand. In addition, we show that our results are robust to homology scheme and analytical method, encouraging further use of the markers employed in this study to continue drawing a broader picture of palpigrade relationships.

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.

Understanding hotspots within a global hotspot – identifying the drivers of regional species richness patterns in terrestrial subterranean habitats

We tested three hypotheses (productive energy, habitat heterogeneity, historical climate stability) to explain regional species richness patterns in subterranean habitats, which have less habitat/climatic variability than surface habitats. For the first time, we investigated the pattern of two species richness hotspots in the worlds richest region in subterranean biodiversity in southeast Europe. We used distribution records for 388 species of beetles, the most species rich group of terrestrial subterranean fauna, belonging to subfamilies Trechinae (Carabidae) and Leptodirinae (Cholevidae), and mapped them onto a 20 × 20 km grid. We applied spatial and non‐spatial multiple regression, using generalised linear models and spatial eigenvector mapping. The relative importance of each hypothesis, and of the spatial versus the environmental components, was assessed with variation partitioning. We analysed the total dataset as well as each subfamily separately. Our results show that although the relative importance of species richness drivers differed among taxonomic groups, in most cases habitat heterogeneity had the biggest influence. It was followed by historical climate stability, while productive energy had a neglecting effect. This proves that even though habitat variability is smaller in subterranean than in surface habitats, its gradient is still strong enough to explain species richness patterns better than the other two hypotheses. Identification of the drivers shaping the two regional species richness hotspots within a global hotspot of highly endemic subterranean fauna is important for conservation practices. Additionally, we contribute to the general understanding of species richness patterns of insects, by providing the first detailed analyses on a regional scale for subterranean systems.

Taxonomy and biogeography of Niphargus steueri (Crustacea: Amphipoda)

Niphargus steueri (Niphargidae) comprises a complex of four subspecies (N. s. steueri, N. s. kolombatovici, N. s. subtypicus, and N. s. liburnicus), the morphology and distribution of which have been poorly known until now. New diagnostic characters of the species and its four subspecies are presented and illustrated. The species is distributed along the major part of the Dinaric Karst, between Slovenia in the northwest and Bosnia and Herzegovina in the southeast. The distribution of the four subspecies approximately resembles the distribution of the evolutionary lineages of the subterranean amphibian Proteus anguinus and the Dinaric lineage of the cave shrimp Troglocaris agg. anophthalmus. Niphargus s. steueri is restricted to the Istran Peninsula; N. s. subtypicus is distributed in southeast Slovenia and northwest Croatia; N. s. liburnicus is known from two disjunctive localities, one on the island of Krk (Croatia) and the other in Gorizia (Italy); and N. s. kolombatovici is restricted to Dalmacija and Herzegovina. The somewhat variable putative synapomorphies of N. steueri probably suggest that the group is old and that the present distribution pattern is a result of historical events, possibly events in the Miocene Dinaride Lake system. Two populations of N. s. kolombatovici and one population of N. s. subtypicus deviate from the general distributional pattern and may belong to cryptic taxa that cannot be distinguished on the basis of morphology. Both hypotheses corroborate with the estimated times of divergence and with the number of independent lineages in the similarly distributed but unrelated stygobionts Proteus and Troglocaris.

Distribution and morphology of the European Karst palpigrade Eukoenenia gasparoi (Arachnida: Palpigradi)

Abstract The first record of the palpigrade Eukoenenia gasparoi Condé 1988 in Croatia is reported. We review the distribution of this troglobiotic species endemic to the classical European Karst region, give an illustrated description of the adult stages and the juvenile female, and evaluate divergence among the populations. Morphological differences reflect individual-level rather than population-level variation.

Mapping Subterranean Biodiversity

The ability to describe and explain the spatial distribution of subterranean fauna is becoming increasingly more important as man continues to expand his reach and encroaches on traditionally inaccessible areas. To that end, it is important to understand the processes that have led to and sustain such distributions, and in the light of recent environmental changes, to help in understanding the impact of future environmental scenarios. Hence, an increasingly urgent need is the ability to accurately map the geographic distribution of various species and ecosystems (and often as critical, the distribution of the required habitat). Mapping includes not only the graphical presentation of species occurrences and derived parameters such as densities and species richness over a region but, more importantly, it includes the statistical spatial modeling that provides both the map and the means of assessing its accuracy. Here we present some statistical approaches that provide such information that can be used in interpretation, hypothesis testing, and decision-making. The methods include a general introduction to geostatistical models as well as spatial autoregressive models for data collected or aggregated to nonoverlapping regions as is common for diversity studies of cave fauna.

Phylogenetic relationships of the Balkan Moitessieriidae (Caenogastropoda: Truncatelloidea)

The family Moitessieriidae includes minute dioecious gastropods exclusively inhabiting subterranean waters, including thermal ones. Only empty shells were collected in most species, the vast majority of them are described from their gross shell morphology alone. Several visits to a site are usually required to obtain at least some living individuals. High variability in shell morphology and the lack of diagnostic features, coupled with anticipated high levels of endemism, has resulted in a long list of nominal moitessierid species. Type specimens stored as empty shells omit unambiguous identification and delimitation of species boundaries. Due to inaccessibility of cave animals and consequent lack of material suitable for molecular analysis, the phylogenetic relationships, as well as the taxonomy of the family at genus/species level, are far from being understood. The anatomy of the family is also poorly known and provided only for a few taxa. The distinctness of the Moitessieriidae has sometimes been questioned, and their monophyly not proved. Twelve species of the Balkan Moitessieriidae are considered: two species of Paladilhiopsis, two species of Bythiospeum, six species of Iglica, Costellina turrita and Lanzaia bosnica. The shell morphology of each species, as well as the reproductive system of Paladilhiopsis and Iglica, were analysed. DNA sequences of nuclear histone H3, ribosomal 18S, ribosomal 28S and mitochondrial cytochrome oxidase subunit I (COI) were applied to infer phylogenetic relationships among the taxa. The sequences of Bythiospeum from GenBank have been used to infer relationships between Bythiospeum and Paladilhiopsis that were recently synonymized. Paladilhiopsis and Iglica are distinct, but closely related genera, as is the genus Bythiospeum, which does not occur in the Balkans. Its relationships with both former taxa remain unresolved. The Moitessieriidae are clearly distinct from all other families of the Truncatelloidea, however, their monophyly remains doubtful.