Research Article |
Corresponding author: Adam Brunke ( adam.j.brunke@gmail.com ) Academic editor: Jan Klimaszewski
© 2017 Adam Brunke, Aleš Smetana, Duncan Carruthers-Lay, Joel Buffam.
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:
Brunke A, Smetana A, Carruthers-Lay D, Buffam J (2017) Revision of Hemiquedius Casey (Staphylinidae, Staphylininae) and a review of beetles dependent on beavers and muskrats in North America. ZooKeys 702: 27-43. https://doi.org/10.3897/zookeys.702.19936
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Based on newly discovered characters on the male genitalia, external morphology and an accumulation of ecological data, we revise the single member of the genus Hemiquedius. Two new species, H. infinitus Brunke & Smetana, sp. n. and H. castoris Brunke & Smetana, sp. n., from eastern North America are described, and H. ferox (LeConte), restricted to peninsular Florida, is re-described. Hemiquedius castoris is strongly associated with the microhabitats provided by nest materials of the North American beaver and muskrat. A key to the three species of Hemiquedius is provided and diagnostic characters are illustrated. We also review the beetles known to be obligate associates of beavers and muskrats, and discuss the potential role of these keystone vertebrates in beetle evolution and distribution. Based on nest-associated beetles and their closest living relatives, beaver and muskrat lodges may extend distributions northward by moderating winters, promote sympatric speciation and act as refugia against extinction of lineages on a broader timescale. Further research into these potential impacts by ecologists and evolutionary biologists is encouraged.
nidicoly, sympatric speciation, cryptic diversity, Nearctic, Staphylinini , Acylophorina
The genus Hemiquedius (Fig.
Here we re-assess the taxonomic status of the ecologically specialized population of Hemiquedius and other putative species based on morphological characters and CO1 barcode data. Although ecosystem engineering by beavers is well known to positively impact populations of wetland fauna such as fish, birds, reptiles and invertebrates (
All specimens were examined using a Nikon SMZ25 stereomicroscope. To allow for the routine dissection of the terminal abdominal segments (including the aedeagus), distilled water was applied directly to the tip of the abdomen using a fine paintbrush. As a precaution against DNA degradation, specimens examined in the present study were never subjected to high ambient humidity relaxing chambers or entirely submersed in water. Genitalia were washed with 70% alcohol and placed in glycerin for observation. Genitalia were placed in glycerin filled vials for long-term storage, which were pinned with their respective specimen.
Measurements were performed using the live measurement module in NIS Elements BR v4.5. Measurements were taken as listed below, but only proportional (HW/HL, PW/PL, EW/EL, ESut/PL, PW/HW) and forebody measurements were stated directly in descriptions due to variability in body size. Total body length is generally difficult to measure accurately in Staphylinidae due to the contractile nature of the abdomen. Abbreviations for measurements are as follows:
HL Head Length, at middle, from the anterior margin of frons to the nuchal ridge.
HW Head Width, the greatest width, including the eyes.
PL Pronotum Length, at middle.
PW Pronotum Width, greatest width.
EL Elytral Length, greatest length taken from level of the anterior most large, lateral macroseta to apex of elytra. Its length approximates the length of the elytra not covered by the pronotum and therefore contributing to the forebody length.
EW Elytral Width, greatest width.
ESut Sutural Length, length of elytral suture.
ForebodyHL + PL + EL.
Line illustrations were performed in Adobe Illustrator CS6 based on photographs. Photomontage was accomplished using a motorized Nikon SMZ25 microscope and NIS Elements BR v4.5. Photos were processed in Adobe Photoshop CS6. Distribution maps were created using SimpleMappr (
Extraction, amplification and sequencing of the barcoding fragment of CO1 was performed by the Biodiversity Institute of Ontario (
A revision of Hemiquedius ferox resulted in the recognition of three species: H. infinitus Brunke and Smetana, sp. n. and H. castoris Brunke and Smetana, sp. n., from eastern North America and H. ferox (LeConte), restricted to peninsular Florida. Although H. infinitus and H. castoris occur sympatrically, H. castoris is strongly associated with the nest material of North American beaver and muskrat, while H. infinitus occurs outside of this microhabitat, along the margins of various wetlands. A total of three DNA barcodes >500bp (barcode compliant) and two incomplete barcodes (176 and 306 bp) were generated from available dried specimens. An additional 3 specimens of H. infinitus were processed but failed to provide sequences, likely due to inadequate preservation. Hemiquedius infinitus and H. castoris were represented by 3 and 2 sequences, respectively, and both species were represented by barcodes >500bp that were assigned BINs. Their process IDs are given in the material examined section under the corresponding species. Although two BINs were identified by BOLD (BOLD:ABW6323 and BOLD:ACL9384), sequences did not cluster by the morphology and ecology-based species concepts proposed herein (tree not shown here). However, an OTU (operational taxonomic unit) cluster analysis of both compliant and incomplete barcode fragments in BOLD suggested only a single OTU (average distance = 0.94%, maximum distance = 2.78%). It is likely that, with additional barcode compliant sequences in the future, the two existing BINs will be synonymized into one. Molecular data were unavailable for H. ferox as DNA from three dried specimens failed to amplify.
1 | Elytral disc with fine setation laterally (Fig. |
H. castoris Brunke and Smetana, sp. n. |
– | Elytral disc without fine setation (Fig. |
2 |
2 | Male sternite VIII with distinct emargination (Fig. |
H. ferox (LeConte) |
– | Male sternite VIII without or with slight emargination (Fig. |
H. infinitus Brunke and Smetana, sp. n. |
Hemiquedius
Casey, 1915: 397, 399;
Hemiquedius can be readily recognized as a member of the subtribe Acylophorina by its elongate, non-lobed and cylindrical mid and hind tarsomeres, and the empodial setae of the hind tarsus, which is distinctly longer than that of the foretarsus. Within the subtribe, Hemiquedius has a unique habitus (Fig.
Quedius ferox LeConte, 1878: 388
Hemiquedius
ferox
:
The male lectotype of Quedius ferox designated by
UNITED STATES: Florida: Dade County: 50 km SW Miami, Chekika State Rec. area, Grossman Hammock Forest, malaise-FIT, ‘66b’, 15.XI.1985 to 24.II.1986, S. & J. Peck, 1 specimen with CNC656114 BOLD Proc ID CNCCT067-17 (21,
Hemiquedius ferox can be distinguished by the distinct emargination of male sternite VIII (Fig.
Measurements ♂ (n = 5): HW/HL 1.18–1.20; PW/PL 0.96–0.98; EW/EL 0.91–0.96; ESut/PL 0.69–0.77; PW/HW 1.21–1.25; forebody length 5.03–5.31 mm.
Measurements ♀ (n = 5): HW/HL 1.14–1.18; PW/PL 0.96–0.97; EW/EL 0.92–0.96; ESut/PL 0.72–0.74; PW/HW 1.24–1.28; forebody length 4.80–5.50 mm.
Coloration: body dark brown, pronotum sometimes moderately paler, dark reddish brown, abdomen with strong iridescence; palpi reddish brown; legs except coxae light reddish to reddish brown, paler than rest of body, coxae dark brown; antennae dark reddish brown, apical 1-2 segments slightly paler.
Head transverse, slightly more so in males, temples slightly smaller to slightly longer than eyes, middle of disc without punctures. Antennomeres elongate, antennomere 3 extremely elongate, segments decreasing in length to penultimate, which is slightly elongate.
Pronotum slightly longer than wide, weakly converging anteriad, disc without microsculpture, wider than head (Fig.
Abdominal tergites with pubescence moderately sparse, setae separated by far more than their diameter, especially sparse at middle of each disc.
Median lobe in lateral view narrowed to simple apex, which is deflexed ventrad at apical fifth (Fig.
Female tergite X elongate triangular, with thin median extension that gradually extends from lateral margin in most specimens, shape overlapping with some specimens of H. infinitus.
Figure
Specimens have been collected using FITs in hammock forests, ‘pinelands’, and one specimen came to a UV light. Two specimens were teneral (3.III to 28.IV, 15.XI to 24.II).
Hemiquedius ferox is distinguishable externally from other species of the genus by the slightly longer pronotum and the distinctly emarginate male sternite VIII.
Gatineau Park, Outaouais region, Quebec, Canada.
Type material. Holotype (♂,
Hemiquedius ferox (Casey) (A, B, E); H. infinitus Brunke and Smetana (C, D, G); and H. castoris Brunke and Smetana (F). Aedeagus in parameral view (A, C), median lobe in lateral view (B, D), paramere (E), left portion of paramere with peg setae (F, G). Scale bars: 0.5 mm (A–E), 0.25 mm (F–G).
(19 ♂ 17 ♀
Hemiquedius castoris can be easily distinguished by the setose lateral portions of the elytral disc (Fig.
Measurements ♂ (n = 5): HW/HL 1.11–1.16; PW/PL 1.01–1.07; EW/EL 0.99–1.04; ESut/PL 0.71–0.77; PW/HW 1.21–1.26; forebody length 5.05–5.81 mm.
Measurements ♀ (n = 5): HW/HL 1.18–1.20; PW/PL 1.02–1.06; EW/EL 0.94–0.97; ESut/PL 0.74–0.77; PW/HW 1.23–1.26; forebody length 5.21–6.06 mm.
Similar to Hemiquedius ferox and differing only in the following: palpi and antennae slightly darker, dark brown to dark reddish brown; antennae on average slightly thinner and shorter in appearance, in most specimens antennomere 8 and 9 slightly less elongate; head slightly more transverse in females rather than males; pronotum slightly wider than long; elytral disc with dense fine setae on lateral portion, scutellum with distinct, transverse meshed microsculpture on entire surface; punctures on abdominal tergites slightly denser; median lobe narrowed to shorter apex, length and shape of narrow apical portion highly variable (as in Fig.
We describe this species in honor of Canada on its 150th birthday. Like its national animal, the North American Beaver, Canada promotes a diverse community within its greater environment. The species epithet refers to the close association of this rove beetle with beaver lodges.
Figure
All specimens with collecting data have been taken from the nest material within beaver or muskrat lodges, some of which were abandoned for several years. Teneral specimens have been collected in August and September.
Hemiquedius castoris is most similar to the sympatric H. infinitus but can be easily distinguished based on the fine setation on the elytral disc. The genitalia of these two species are extremely similar and only differ by the shape of the paramere (Fig.
3 mi northwest of Orange, Orange County, Texas.
Holotype (♂,
(13 ♂ 17 ♀
United States: Alabama: Mobile County: Mt. Vernon, 20.III.1932, H. Dietrich (1,
Hemiquedius infinitus can be distinguished by a combination of the elytral disc without fine dense setae (Fig.
Measurements ♂ (n = 5): HW/HL 1.15–1.21; PW/PL 1.00–1.05; EW/EL 0.92–0.95; ESut/PL 0.72–0.79; PW/HW 1.19–1.27; forebody length 5.24–5.53 mm.
Measurements ♀ (n = 5): HW/HL 1.17–1.21; PW/PL 1.00–1.04; EW/EL 0.91–0.94; ESut/PL 0.75–0.77; PW/HW 1.21–1.27; forebody length 5.30–5.87 mm.
Extremely similar to H. castoris and differing only in the following: elytral disc without fine dense setae (Fig.
The species epithet means unbounded in Latin and refers to the occurrence of this species in a variety of wetland habitats, though not inside the lodges of beavers or muskrats.
Figure
Specimens have been collected from a variety of wetland edge habitats ranging from open eutrophic ponds to shaded vernal forest pools.
Hemiquedius infinitus is most similar to H. castoris but can be easily distinguished based on the lack of fine dense setae on the elytral disc. The genitalia of these two species are extremely similar, variable and only differ by the shape of the paramere. At present H. infinitus is not known to be sympatric with H. ferox but may overlap with it in northern Florida.
A taxonomic revision of Hemiquedius ferox revealed the existence of three distinct species: one known only from peninsular Florida and a pair of highly similar and sympatric eastern species that are thus far allopatric with the former. The eastern pair of species represent an unusual situation in Staphylinidae, where CO1 barcodes are not diagnostic and male genitalia are almost identical (contra
The distribution of Hemiquedius castoris is certainly greater than that reported here. We expect this species to occur in at least Wisconsin to New England and across the maritime provinces of Canada. Beaver and muskrat lodges are poorly sampled and the presence of H. castoris in the boreal forest region makes it likely to be rather widely distributed across Canada. The North American Beaver and Muskrat do not occur in peninsular Florida (
Thus far, eleven species of beetle are obligate associates of beaver and muskrat lodges in North America (Table
Obligate associations of beetles with the lodges of beavers and muskrats in North America.
Family | Subfamily | Species |
---|---|---|
Carabidae | Harpalinae |
Pterostichus castor Goulet & Bousquet ( |
Patrobinae |
Platypatrobus lacustris Darlington ( |
|
Leiodidae | Platypsyllinae |
Leptinillus validus (Horn) ( |
Platypsyllus castoris Ritsema ( |
||
Staphylinidae | Aleocharinae |
Aleodorus partitus (LeConte) ( |
Myrmecocephalus gatineauensis Hoebeke ( |
||
Micropeplinae |
Micropeplus browni Campbell ( |
|
Oxytelinae |
Coprophilus castoris Campbell ( |
|
Staphylininae |
Gabrius vindex Smetana ( |
|
Hemiquedius castoris Brunke & Smetana, sp. n. | ||
Quedius campbelli Smetana ( |
We would like to thank the Biodiversity Institute of Ontario for processing and sequencing of specimens and especially, V. Levesque-Beaudin (Guelph, Canada) for suggesting the OTU analysis in BOLD. V. Grebennikov (Ottawa, Canada) provided assistance with dataset publication in BOLD and P. Bouchard (Ottawa, Canada) facilitated support for sequencing.