Die Akustik der Anzeigerufe der Frösche - Einflüsse ihrer Umwelt und Biologie im Kontrast zur ihrer stammesgeschichtlichen Verwandtschaft

In ihrer stammesgeschichtlichen Entwicklung haben, neben Säugetieren, Vögeln und Insekten, auch Froschlurche ein umfangreiches Repertoire an akustischen Signalen zur Identifizierung arteigener Individuen und anlocken potenzieller Paarungspartner entwickelt. Diese sogenannten Anzeigerufe sind dabei für jede Art einzigartig. Beobachtungen zeigen aber, dass es neben dieser Artspezifität, auch Ähnlichkeiten in den Anzeigerufen zwischen nicht näher verwandten Arten existieren. Es stellt sich daher die Frage woher diese Ähnlichkeiten stammen. Stellen diese Ähnlichkeiten eine Anpassung an die Bedingungen der Lebensräume dar (konvergente Evolution) oder sind sie ein Ergebnis der stammesgeschichtlichen Entwicklung der Arten (divergente Evolution). Zur Klärung dieser Frage habe ich Anzeigerufe von ca. 1500 Arten aus den unterschiedlichsten Lebensräumen unseres Planten gesammelt und ausgewertet. Eine Korrelation der gemessenen akustischen Eigenschaften (z. B. dominante Frequenz) mit der Phylogenie der Amphibien sollte dabei klären, inwieweit die Phylogenie mit diesen akustischen Eigenschaften verknüpft ist. Vergleiche zwischen verschiedenen Kategorien aus Morphologie, Verhalten und Lebensraum in Bezug auf die akustischen Eigenschaften wiederum sollten mögliche Anpassungen der akustischen Eigenschaften herausstellen. Es stellte sich am Ende heraus, dass einige akustische Eigenschaften (z. B. dominante Frequenz) sowohl ein Ergebnis einer divergenten Evolution sind, als auch einer konvergenten Evolution. Zusätzlich war es mir möglich die Anzeigerufe in separate Gilden einzuteilen, die ähnliche strukturellen Eigenschaften aufweisen. Gilden in die Arten unabhängig von ihren verwandtschaftlichen Beziehungen eingeordnet werden können. Ein Werkzeug was Vergleiche zwischen Arten anhand ihrer Akustik vereinfacht und die Möglichkeit gibt zu verstehen wie Arten die Bedingungen ihrer Lebensräume auf ähnliche akustische Weise nutzen.Beside mammals, birds and insects also anurans developed at their evolutionary history a wide repertoire of acoustic signals to identify conspecific individuals and to attract possible mating partners. These so-called advertisement calls are unique to every single species. However, beside this species-specific uniqueness we can also observe astonishing similarities among advertisement calls of not close related species. Therefore, there is the question of where these similarities came from. Are these similarities adaptations to conditions to similar biology’s and environments and so a result of a convergent evolution or these similarities arose by the anuran phylogeny and represent a divergent evolution? To answer these questions I collected and measured advertisement calls of ca. 1500 anuran species around the globe of different living habitats. A correlation between phylogeny and acoustic properties (e.g. dominant frequency) could show the influence of the phylogeny at the evolved acoustic traits. Comparisons among different categories of morphology, behaviour and habitat concerning the acoustic traits could show possible adaptations. The result of my research showed that some structural and spectral properties are a consequence of the phylogenetic history as well as an adaptation to conditions of biology and environment. Both, the divergent and the convergent evolution place a role in these cases. Additional I managed to introduce a system to order anuran advertisement calls into distinct guilds. These guilds show how different species uses their acoustic properties in a similar matter. An additional tool to make comparisons among species easier and to understand how anuran uses environments in a similar acoustic way

The taxonomic status of two West African Leptopelis species: L. macrotis Schiøtz, 1967 and L. spiritusnoctis Rödel, 2007 (Amphibia: Anura: Arthroleptidae)

We herein examine the taxonomic status of two West African forest-dwelling Leptopelis species. The small L. spiritusnoctis, described from the Upper Guinean forests of West Africa, was recently synonymized with L. aubryi, described from Gabon. The large L. macrotis, known from Ghana to Sierra Leone, was downgraded to a subspecies of L. millsoni, ranging from the Niger Delta to eastern Democratic Republic of Congo. These taxonomic decisions are in contrast to the general biogeographic pattern of African forest anurans and we consequently tested if the morphologically similar taxon pairs are indeed conspecifics by applying acoustic and molecular techniques. Both techniques confirmed that populations from West Africa differ significantly from their Central African morphological equivalents. Consequently, we herein resurrect L. spiritusnoctis as a valid species. The acoustic data indicate that L. aubryi may comprise a complex of cryptic species. We further advocate using the name L. macrotis for West African and L. millsoni for Central African populations of these larger arboreal frogs. However, we had neither genetic nor acoustic data from the type locality of L. millsoni available and could not clarify if these frogs belong to the more western or eastern taxon or even represent a Nigerian endemic. Thus, it is possible that West African populations need to be termed L. millsoni in the future. For populations east of the Cross River, Nigeria, the name L. guineensis would be available

Two new Phrynobatrachus species (Amphibia: Anura: Phrynobatrachidae) from the Republic of the Congo

We describe two new species of puddle frogs, genus Phrynobatrachus, from the south-western Republic of the Congo. One of them, P. horsti sp. nov., occurs also in neighbouring Gabon and is morphologically most similar to the Cameroonian P. ruthbeateae. It differs from the latter species by smaller males with longer thighs and shanks. The new species comprises various colour morphs but always has less conspicuous black borders between flanks and belly than P. ruthbeateae. The distinct and large black axillary blotch of P. ruthbeateae is either much smaller in P. horsti sp. nov., or broken into numerous irregularly shaped smaller dots. Similarly, a black transversal line at the anterior ventral border of thighs and the black face mask is less distinct and irregularly delimitated in P. horsti sp. nov. when compared to P. ruthbeateae. The mean genetic difference in the sampled region of the 16S rRNA gene between P. horsti sp. nov. and 40 other western African congeners range from 3.66-18.10%. The second new species, P. mayokoensis sp. nov., differs from all other known congeners by the combination of a compact and warty body, the absence of a spiny eyelid tubercle and pedal webbing, a conspicuous black triangle on throat and anterior part of the belly, and a distinct large red blotch on the anteriorproximal surface of the thighs. It exhibited a mean genetic difference in the 16S rRNA to 40 other western African congeners ranging from 1.34-16.98%. The genetically most similar sequence stems from a GenBank entry of a Gabonese frog, determined as P. ogoensis. A comparison of the new species with P. ogoensis syntypes confirmed their specific distinctiveness, most convincingly underlined by the absence of pedal webbing in the new species and the pronounced pedal webbing in P. ogoensis. The GenBank entry thus most likely is based on a misidentification and P. mayokoensis sp. nov. may also occur in neighbouring Gabon. The discovery of the two new frog species is further evidence of the huge gap in our knowledge concerning the species richness in the Guineo-Congolian rainforest

A guild classification system proposed for anuran advertisement calls

Zoologists have widely acknowledged the utility of classification systems for characterising variation in anuran egg and clutch types, tadpole morphotypes, embryonic and tadpole development, amplexus types and reproductive modes. These classification systems have facilitated unambiguous communication between researchers, often working in completely different fields (e.g. taxonomy, ecology, behaviour), as well as comparisons among studies. A syntactic system, classifying anuran call guilds, is so far lacking. Based on examination of the calls of 1253 anuran species we present a simple, easy to use dichotomous key and guild system for classifying anuran advertisement calls – the call type most frequently emitted by anurans and studied by researchers. The use of only three call elements, namely clearly-defined calls, notes, and pulses, plus presence or absence of frequency modulation, allows assigning all currently known anuran advertisement calls to one of eight distinct call guilds defined here. This novel toolkit will facilitate comparative studies across the many thousand anuran species, and may help to unravel drivers of anuran call evolution, and to identify ecological patterns at the level of acoustic communities

A new Puddle Frog, genus Phrynobatrachus (Amphibia: Anura: Phrynobatrachidae), from the eastern part of the Upper Guinea <br />biodiversity hotspot, West Africa

Kpan, Tokouaho Flora, Kouamé, N'Goran Germain, Barej, Michael F., Adeba, Patrick Joël, Emmrich, Mike, Ofori-Boateng, Caleb, Rödel, Mark-Oliver (2018): A new Puddle Frog, genus Phrynobatrachus (Amphibia: Anura: Phrynobatrachidae), from the eastern part of the Upper Guinea biodiversity hotspot, West Africa. Zootaxa 4388 (2): 221-237, DOI: https://doi.org/10.11646/zootaxa.4388.2.

The use of bioacoustics in anuran taxonomy: theory, terminology, methods and recommendations for best practice

Vocalizations of anuran amphibians have received much attention in studies of behavioral ecology and physiology, but also provide informative characters for identifying and delimiting species. We here review the terminology and variation of frog calls from a perspective of integrative taxonomy, and provide hands-on protocols for recording, analyzing, comparing, interpreting and describing these sounds. Our focus is on advertisement calls, which serve as premating isolation mechanisms and, therefore, convey important taxonomic information. We provide recommendations for terminology of frog vocalizations, with call, note and pulse being the fundamental subunits to be used in descriptions and comparisons. However, due to the complexity and diversity of these signals, an unequivocal application of the terms call and note can be challenging. We therefore provide two coherent concepts that either follow a note-centered approach (defining uninterrupted units of sound as notes, and their entirety as call) or a call-centered approach (defining uninterrupted units as call whenever they are separated by long silent intervals) in terminology. Based on surveys of literature, we show that numerous call traits can be highly variable within and between individuals of one species. Despite idiosyncrasies of species and higher taxa, the duration of calls or notes, pulse rate within notes, and number of pulses per note appear to be more static within individuals and somewhat less affected by temperature. Therefore, these variables might often be preferable as taxonomic characters over call rate or note rate, which are heavily influenced by various factors. Dominant frequency is also comparatively static and only weakly affected by temperature, but depends strongly on body size. As with other taxonomic characters, strong call divergence is typically indicative of species-level differences, whereas call similarities of two populations are no evidence for them being conspecific. Taxonomic conclusions can especially be drawn when the general advertisement call structure of two candidate species is radically different and qualitative call differences are thus observed. On the other hand, quantitative differences in call traits might substantially vary within and among conspecific populations, and require careful evaluation and analysis. We provide guidelines for the taxonomic interpretation of advertisement call differences in sympatric and allopatric situations, and emphasize the need for an integrative use of multiple datasets (bio-acoustics, morphology, genetics), particularly for allopatric scenarios. We show that small-sized frogs often emit calls with frequency components in the ultrasound spectrum, although it is unlikely that these high frequencies are of biological relevance for the majority of them, and we illustrate that detection of upper harmonics depends also on recording distance because higher frequencies are attenuated more strongly. Bioacoustics remains a prime approach in integrative taxonomy of anurans if uncertainty due to possible intraspecific variation and technical artifacts is adequately considered and acknowledged

Life in the spray zone - overlooked diversity in West African torrent-frogs (Anura, Odontobatrachidae, Odontobatrachus)

West African torrent-frogs of the genus Odontobatrachus currently belong to a single species: Odontobatrachus natator (Boulenger, 1905). Recently, molecular results and biogeographic separation led to the recognition of five Operational Taxonomic Units (OTUs) thus identifying a species-complex. Based on these insights, morphological analyses on more than 150 adult specimens, covering the entire distribution of the family and all OTUs, were carried out. Despite strong morphological congruence, combinations of morphological characters made the differentiation of OTUs successful and allowed the recognition of five distinct species: Odontobatrachus natator, and four species new to science: Odontobatrachus arndti sp. n., O. fouta sp. n., O. smithi sp. n. and O. ziama sp. n. All species occur in parapatry: Odontobatrachus natator is known from western Guinea to eastern Liberia, O. ziama sp. n. from eastern Guinea, O. smithi sp. n. and O. fouta sp. n. from western Guinea, O. arndti sp. n. from the border triangle Guinea-Liberia-Cote d'Ivoire. In addition, for the first time the advertisement call of a West African torrent-frog (O. arndti sp. n.) is described