Corresponding author: Michael Balke (
Academic editor: Oana Moldovan
We describe a new subterranean species of the genus
Balke M, Ribera I (2020) A subterranean species of
Here we report the discovery of a new subterranean diving beetle from the Malay Peninsula. This species was placed in the
Specimens were studied with a Leica M205C stereo microscope at 10–160x. Images were taken with a Canon EOS 5DS camera fitted with a Mitutoyo 10x ELWD Plan Apo objective attached to a Carl Zeiss Jena Sonnar 3.5 / 135 MC as focus lens. Illumination was with two to four LED segments SN-1 from Stonemaster (
Drawings were produced with a camera lucida, first sketched with pencil on paper, then photographed and digitally inked using an iPad Pro and the Concepts as well as MediBang Paint APPs.
One paratype male of the new species (voucher number IBE-AN1160) was used for a non-destructive DNA extraction using a commercial kit (Qiagen DNeasy Tissue Kit). We successfully amplified six mitochondrial and nuclear genes in five sequencing reactions, two cytochrome c oxidase subunit I fragments (COI-5’ -the "barcode"- and COI-3’), 5’ end of rrnL RNA plus leucine tRNA transfer (tRNA-L1) plus 5’ end of NADH dehydrogenase subunit I (NAD1), and one internal fragment of both small ribosomal unit (18S RNA) and Histone 3 (H3) (see
The combined dataset was analysed with a fast maximum likelihood search as implemented in IQ-TREE v1.6 (
Malaysia, Pahang, Cameron Highlands, Tanah Rata,
Testaceous and slightly translucent (Figs
Head and pronotum with distinct microreticulation formed by small regular cells and fine moderately dense punctation. Elytra with distinct microreticulation formed by small regular cells and dense, coarse, setiferous punctation (Fig.
Eyes fully reduced, with only small black scars remaining on surface of head (Figs
Antennomeres filiform to slightly moniliform (Fig.
Named after Kazuki Sugaya, the discoverer of this species.
This species differs from all other
Collected from two helocrenes on a slope in forested area. The beetles were observed creeping around and were not swimming when observed (K. Sugaya personal communication 2019) (Fig.
The best evolutionary model fitting the data according to Modelfinder was a GTR+F for all partitions.
Ventral view of
Habitat of
Most species of
The lotic beetles often hide in the gravel when disturbed, and observations of M. Balke in New Guinea suggest that the interstitial of riverbanks is often utilized by these beetles, possibly to avoid downstream drift. The beetles seem to avoid habitat with fine, dense substrates, which we suggest make it hard to hide as such substrate clogs the space between stones and pebbles (see also
This lifestyle could be interpreted as a preadaptation for interstitial or stygobitic life. In fact, some Australian species seem to mainly inhabit the interstitial, and have been suggested to provide a scenario for the transition from epigean to stygobitic life (
Biogeographically, the occurrence of Southeast Asian and a Chinese species of
Simplified phylogenetic tree obtained with IQ-TREE using the DNA sequence dataset of
We express our sincere thanks to Kazuki Sugaya for sending the specimens studied here to the senior author, and Anabela Cardoso for laboratory work. Helena Shaverdo and Günther Wewalka (Vienna) provided very valuable reviews of the submitted manuscript. This research was supported by DFG Ba2152/4-1, 7-1, 11-1, 11-2 and 24-1. Michael Balke acknowledges support from the EU SYNTHESYS program projects FR-TAF-6972 and GB-TAF-6776.