Biodiversity Data Journal :
Taxonomic Paper
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Corresponding author:
Academic editor: Miguel Alonso-Zarazaga
Received: 05 Nov 2015 | Accepted: 18 Dec 2015 | Published: 22 Dec 2015
© 2015 Michael Balke, Bernhard Ruthensteiner, Evie Warikar, Katja Neven, Lars Hendrich
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Balke M, Ruthensteiner B, Warikar E, Neven K, Hendrich L (2015) Two new species of Limbodessus diving beetles from New Guinea - short verbal descriptions flanked by online content (digital photography, μCT scans, drawings and DNA sequence data). Biodiversity Data Journal 3: e7096. https://doi.org/10.3897/BDJ.3.e7096
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To date only one species of Limbodessus diving beetles has been reported from the Island of New Guinea, L. compactus (Clark, 1862), which is widerspread in the Australian region.
We describe two new species of microendemic New Guinea Limbodessus and use a compact descriptive format flanked by enriched online content in wiki powered species pages. Limbodessus baliem sp.n. is described from ca. 1,600 m altitude in the Baliem Valley of Papua and Limbodessus alexanderi sp.n. from >3,000 m altitude north of Sugapa, Papua.
Based on our analysis, we also transfer three species from other genera to Limbodessus Guignot, 1939, with the following changes: Limbodessus deflectus (Ordish, 1966), new combination; Limbodessus leveri (J. Balfour-Browne, 1944), new combination; and Limbodessus plicatus (Sharp, 1882), new combination.
Dytiscidae, Limbodessus, new species, high resolution photography, μCT scans, DNA sequence data, minimalistic descriptions, New Guinea
Limbodessus
Here we describe two new microendemic species from New Guinea. One occurs in an intramontane depression at 1,600–1,700 m and the other one in the tropical-montane to alpine habitat above 3,000 m. We utilize a compact, integrative descriptive format following
Specimens are in the following collections:
CLH Collection of Lars Hendrich, Munich, Germany (property of NHMW)
NHMW Naturhistorisches Museum Wien, Vienna, Austria
NMPC National Museum, Prague, Czech Republic
ZSM Zoologische Staatsammlung München, Munich, Germany
Measurements were taken with a Leica M205 C stereomicroscope. The following abbreviations were used: TL (total body length), TL-H (total body length without head), and MW (maximum body width). UNCEN legit indicates specimens collected during a field course with the Cendrawasih University, Jayapura, Papua (UNCEN).
DNA sequence data were generated using standard methods described in detail in our laboratory wiki: http://zsm-entomology.de/wiki/The_Beetle_D_N_A_Lab
Digital images were taken with a Nikon D3X equipped with a bellow or expansion rings and lenses: Mitutoyo 10x ELWD Planapo or Leitz Photar 25/2.8. Illumination came from three compact Nikon flashes, and the instrument was moved on an Isel linear drive or Cognisys Stackshot (for very small steps 1–7 μm). Image stacks were combined using the method A in Helicon focus software.
For micro-CT scanning, the specimens were attached with soft dental wax to tips of glass Pasteur pipettes. Scanning was performed with a Phoenix Nanotom M (GE Measurement & Control, Wunstorf, Germany) cone beam CT scanner at a voltage of 60 kV and a current of 240mA (Limbodessus baliem, Kaef2-gr) or a voltage of 50 kV and a current of 275 mA (Kaef2-kl) respectively, using a molybdenum target. Each scan took 144 minutes. 1.440 projections were prepared per scan. The 3D datasets (prepared with the datos|x reconstruction software, GE Measurement & Control) were examined by volume rendering with Drishti 2.3.2
In addition, surface meshes were generated using the threshold tool in the segmentation editor of the software Amira 5.4.5 (FEI VisualizationSciences Group, Burlington MA, USA). For varying intensities in the volume data, the threshold was slightly locally adjusted. The attachment wax, which has X-ray absorption nearly as intense as that of the specimens’ skeletons, was removed during segmentation by a combination of threshold and manual (lasso and brush tools) segmentation. To constrain total mesh complexity (eventually to ca. one million faces) and reduce file size to a tolerable level, all internal structures were removed.
The PDF 3D models were prepared largely following the procedures outlined by
DNA sequences were uploaded to EMBL and are available under accession numbers LN884305–LN884314.
The cox1 sequences are available in alignment format on Dryad: doi:10.5061/dryad.q1b24. Newly generated data are appended here in fasta format Suppl. material
Animated videos of the μCT scans are available at YouTube tagged as "Limbodessus". The μCT data were deposited in the Morphosource database in their own project.
A large, dark brown to black Limbodessus: length of body 3.0–3.5 mm (N=20); with pronounced habitus disruption between pronotum and elytron Figs
Sexes dimorphic, see below.
Antenna filiform Figs
Antenna with strongly enlarged antennomeres forming a conspicuous club Figs
Named after Alexander Riedel who discovered this species. The species name is a noun in the genitive case.
Indonesian New Guinea, known only from the type locality which is the mountain range north of Sugapa, Papua (Fig.
Puddles in high altitude grassland in the tropical montane / subalpine habitat. Here, a second, much smaller and black Limbodessus was also collected which is the female of an undescribed species.
The species is most likely not threatened due to its occurrence on remote high altitude plateau.
Higher resolution digital images, μCT data as well as sequence data have been deposited in public databases. The Species-ID species page is a versioned wiki site and can be enhanced through community contributions
Partial 3' cox1 sequence deposited at: LN884309–LN884312.
A large, mainly yellow to orange Limbodessus: length of body 2.6–3.0 mm (N=20); with slight habitus disruption between pronotum and elytron Figs
Sexes dimorphic, see below.
Antenna filiform Figs
Antenna moniliform Fig.
The species is named after the type locality, the Baliem River Valley. The name is a noun in the nominative singular standing in apposition.
Indonesian New Guinea, known only from the Baliem Valley which also contains the type locality Wamena (Fig.
The species was collected from small bodies of stagnant water around Wamena in the vast, flat valley floor of the Baliem Valley Figs
Aquatic habitats in the Baliem Valley in general are threatened by eutrophication from domestic animals, fish farming to some degree and increasing intensity of gardening throughout the valley.
Higher resolution digital images, μCT data as well as sequence data have been deposited in public databases. The Species-ID species page is a versioned wiki site and can be enhanced through community contributions
Partial 3' cox1 sequence deposited at: LN884313–LN884314.
Deposited in Morphosource.
Key to New Guinea Limbodessus Based on |
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1 | Base of elytral epipleuron with raised transverse carina delineating a basal pit, see Fig. |
Limbodessus compactus (Clark, 1862) |
– | Base of elytral epipleuron without raised transverse carina delineating a basal pit as in Fig. |
2 |
2 | Elytral plica present; beetle mainly yellowish; microendemic of the Baliem Valley of Papua | Limbodessus baliem sp.n. |
– | Elytral plica absent; beetle dark brown to blackish; only known from high altitude grassland of the range north of Sugapa, Papua | Limbodessus alexanderi sp.n. |
We obtained sequence data for the 3' end of the mitochondrial cytochrome oxidase I gene and analyzed these in the context of our database of Australasian diving beetles
As another result of our analysis, we propose new combinations for the following three species:
Limbodessus deflectus (
- Liodessus deflectus
Limbodessus leveri (
- Bidessus leveri
Limbodessus plicatus (
- Bidessus plicatus
- Liodessus plicatus (
The merits and possible applications of (X-ray) Micro-CT for arthropod systematics have recently been discussed by
In our examples the CT examination provided comprehensive information on overall morphology; general proportions as well as external surface details could be assessed. Regarding surface details, Micro-CT complements conventional ways of examinations, such as light microscopic photography and SEM. Both methods are superior concerning structural surface details. In addition, light microscopy provides true colours. In the specimens examined in the present study, the X-ray absorption was relatively poor, this might be the reason for some deficiencies in structural resolution. In places, internal structures cannot be discerned. For example, the elytra could not be separated from the underlying material.
The external surface renderings appear to be a very useful approach for distributing the CT data. By interactive manipulation, these polygonal mesh surfaces enable intuitive understanding of overall proportions of the specimens. They also contain an enormous amount of geometric information that could easily be extracted and used for e.g., morphometric studies. The 3D PDF models make the entire external morphological information available to “readers”, who might use this information in further comparative studies.
In order to also provide information on specimen coloration and surface microsculpture, we provided digital photographs of different aspects of the beetles using a high throughput, automated imaging approach that could easily be implemented by a technician. The goal was to optimize image quality and time spent on each image so that taxonomically relevant or potentially interesting details can be recognized easily. Digital imaging does, in our opinion, still outperform CT examination for routine work and in terms of documentation of taxonomically relevant structures in the beetles studied here.
We thank Alexander Riedel for sharing speciemens. Fieldwork of the Cendrawasih University UNCEN was organized by Dr S. Surbakti which is greatly appreciated here. Dr Matthew van Dam kindly helped with the linguistic check of the paper which is highly appreciated here.
MB and LH designed the study and conducted the taxonomic work and fieldwork. MB took high resolution digital images and SEMs and conducted the molecular work. BR conducted the uCT work and wrote the corresponding part of the paper. ELW organized and conducted fieldwork. KN performed illustration work.
A fasta file containing the cox1 sequences newly generated for this project.