Belongs within: Hydroporinae.
Contains: Bidessus, Guignotus, Tjirtudessus.
The Bidessini is a clade of water beetles in which females of most members (except the basalmost Hydrodessus) possess a strongly sclerotised, stout spine within the spermatheca. Hydrodessus shares with other bidessins fusion of the metacoxae and abdominal sternite 2. A clade excluding Hydrodessus and Amarodytes (previously treated as the Bidessini sensu stricto) is further supported by the presence of bi-segmented lateral lobes on the male genitalia (Miller 2001). Hydrodessus is a Neotropical genus characterised by a lack of basal pronotal striae or of prominent carinae on the elytra. The genus Limbodessus, found in Australia and New Guinea, includes a radiation of stygobiotic beetles in Western Australia (Watts & McRae 2013).
Hydroglyphus pusillus, the tiny tiger
Published 2 July 2021
Let’s take another visit to the world of diving beetles. Above is Hydroglyphus pusillus, one of the few representatives in northern Europe of a genus that otherwise includes close to ninety species spread through the Old World, primarily in the tropics. Hydroglyphus species are tiny diving beetles, only about two or three millimetres in length, with an elongate oval body shape. Characteristic features of the genus include basal striae on the pronotum and elytra, sutural striae on the elytra, and no transverse stria on the top of the head (Watts 1978, as Guignotus, a subsequently synonymised name). Species are often marked with distinctive colour patterns of streaks and blotches.
Despite their small size, Hydroglyphus species are (like other diving beetles) voracious predators of other aquatic insects. Bellini et al. (2000) investigated the possible role of H. pusillus in controlling mosquito larvae in flooded rice fields in Italy. The larvae of H. pusillus mostly kept to the bottom sediment (so might be expected to be hunting prey other than mosquitoes) but adults were the most abundant diving beetle in the water column at the surveyed locations. One might expect that H. pusillus would not be effective predators of mosquito larvae that greatly outsized them. One would be wrong: not only are they indeed capable of taking down mosquitoes, Bellini et al. went so far as to describe their effects as “a real slaughter”. A diving beetle latching onto a mosquito larva would soon find itself joined by others seemingly scenting haemolymph in the water. Between them, this mob of beetles could destroy a larva in a matter of seconds. Tiny, but terrifying.
Systematics of Bidessini
<==Bidessini |--HydrodessusM01 `--+--Amarodytes Régimbart 1900M01, LM87 `--+--HydroglyphusM01 | |--H. flammulatusBP00 | |--H. geminusVB21 | |--H. japonicusM01 | |--H. pusillusBP00 | `--H. signatellusBP00 |--Limbodessus Guignot 1939M01, WM13 | |--*L. compactus (Clark 1862) [=Hydroporus compactus]WM13 | |--L. bennetti Watts & McRae 2013WM13 | |--L. cunyuensisWM13 | |--L. narryerensisWM13 | `--L. neoguineensis (Régimbart 1892) [=Bidessus neoguineensis]LM87 |--+--Allodessus Guignot 1953M01, LM87 | | `--*A. bistrigatus (Clark 1862) (see below for synonymy)LM87 | |--Uvarus Guignot 1939M01, LM87 | | |--*U. lacustris (Say 1823) [=Hydroporus lacustrus, Amarodytes (*Uvarus) lacustris]LM87 | | |--U. chappuisi (Peschet 1932)S86 | | |--U. granariusRL01 | | `--U. pictipes (Lea 1899) [=Bidessus pictipes]LM87 | `--Bidessodes Régimbart 1900M01, LM87 | |--*B. semistriatus Régimbart 1900LM87 | |--B. bilita Watts 1978LM87 | |--B. denticulatus (Sharp 1882) [=Bidessus denticulatus]LM87 | |--B. flavosignatus (Zimmermann 1922) [=Bidessus flavosignatus]LM87 | |--B. grossus (Zimmermann 1922) [=Bidessus grossus]LM87 | |--B. gutteridgei Watts & Humphreys 2003BW04 | |--B. jucundusM01 | |--B. limestoneensis Watts & Humphreys 2003BW04 | `--B. mjobergi (Zimmermann 19220 [=Bidessus mjobergi]LM87 `--+--Bidessonotus Régimbart 1895M01, LM87 | `--B. obtusatusM01 |--+--Neoclypeodytes Young 1967M01, RL01 | | |--N. cinctellusM01 | | `--N. leachiM01 | `--+--Brachyvatus Zimmermann 1919M01, RL01 | | |--B. acuminatusM01 | | `--B. apicatusRL01 | `--HemibidessusM01 | |--H. bifasciatusM01 | |--H. celinoidesM01 | |--H. conicusM01 | |--H. plaumanniM01 | `--H. spiroductusM01 `--+--Anodocheilus Babington 1841M01, RL01 [incl. Anodontochilus Régimbart 1895RL01] | |--A. exiguusRL01 | |--A. francescaeRL01 | `--A. maculatusM01 `--Liodessus Guignot 1939M01, LM87 |--*L. affinis (Say 1823) [=Hydroporus affinis, Bidessonotus (*Liodessus) affinis]LM87 |--L. amabilis (Clark 1862) [=Hydroporus amabilis]LM87 |--L. antrias Guignot 1955S86 |--L. dispar (Sharp 1882) [=Bidessus dispar; incl. B. elegans Lea 1899]LM87 |--L. gemellus (Clark 1862) [=Hydroporus gemellus; incl. Bidessus mundus Sharp 1882]LM87 |--L. inornatus (Sharp 1882) [=Bidessus inornatus; incl. B. biformis Sharp 1882]LM87 |--L. obscurellusM01 |--L. praelargus (Lea 1899) [=Bidessus praelargus]LM87 `--L. shuckardii (Clark 1862) [=Hydroporus shuckardii]LM87 Bidessini incertae sedis: Crinodessus Miller 1997BW04 `--C. amyae Miller 1997BW04 Phreatodessus Ordish 1976S86 |--P. hades Ordish 1976S86 `--P. pluto Ordish 1991BW04 Kuschelydrus Ordish 1976S86 `--K. phraeticus Ordish 1976BW04 Trogloguignotus Sanfilippo 1958S86 `--T. concii Sanfilippo 1958S86 BidessusB14 Clypeodytes Régimbart 1894LM87 |--*C. cribrosus (Schaum 1864) [=Hydroporus cribrosus]LM87 |--C. bifasciatus (Zimmermann 1922) [=Bidessus (Clypeodytes) bifasciatus]LM87 |--C. darlingtoni Watts 1978LM87 `--C. migrator (Sharp 1882) [=Bidessus migrator]LM87 GuignotusLM87 Gibbidessus Watts 1978LM87 `--*G. chipi Watts 1978LM87 Terradessus Watts 1982LM87 `--*T. caecus Watts 1982LM87 TjirtudessusBW04 Comaldessus Spangler & Barr 1995BW04 `--*C. stygius Spangler & Barr 1995NR97 Sinodytes Spangler 1996BW04 `--S. hubbardi Spangler 1996BW04 Glareadessus Wewalka & Biström 1998BW04 |--G. franzi Wewalka & Biström 1998BW04 `--G. stocki Wewalka & Biström 1998BW04 Neobidessus Young 1967RL01 |--N. pulloidesRL01 `--N. pullusRL01 Boongurrus Larsson 1994NR97 `--*B. rivulus Larsson 1994NR97
*Allodessus bistrigatus (Clark 1862) [=Hydroporus bistrigatus, Bidessus bistrigatus; incl. B. granularis Balfour-Browne 1944, Hydroporus luridus Macleay 1871, B. luridus, B. pallidus Lea 1899]LM87
*Type species of generic name indicated
References
[BW04] Balke, M., C. H. S. Watts, S. J. B. Cooper, W. F. Humphreys & A. P. Vogler. 2004. A highly modified stygobiont diving beetle of the genus Copelatus (Coleoptera, Dytiscidae): taxonomy and cladistic analysis based on mitochondrial DNA sequences. Systematic Entomology 29: 59–67.
[BP00] Bellini, R., F. Pederzani, R. Pilani, R. Veronesi & S. Maini. 2000. Hydroglyphus pusillus (Fabricius) (Coleoptera Dytiscidae): its role as a mosquito larvae predator in rice fields. Boll. Ist. Ent. “G. Grandi” Univ. Bologna 54: 155–163.
[B14] Bouchard, P. (ed.) 2014. The Book of Beetles: A lifesize guide to six hundred of nature’s gems. Ivy Press: Lewes (United Kingdom).
[LM87] Lawrence, J. F., B. P. Moore, J. E. Pyke & T. A. Weir. 1987. Zoological Catalogue of Australia vol. 4. Coleoptera: Archostemata, Myxophaga and Adephaga. Australian Government Publishing Service: Canberra.
[M01] Miller, K. B. 2001. On the phylogeny of the Dytiscidae (Insecta: Coleoptera) with emphasis on the morphology of the female reproductive system. Insect Systematics and Evolution 32: 45–92.
[NR97] Nilsson, A. N., & R. E. Roughley. 1997. The genus- and family-group names of the Dytiscidae—additions and corrections. Beiträge zur Entomologie 47 (2): 359–364.
[RL01] Roughley, R. E., & D. J. Larson. 2001. Dytiscidae Leach, 1815. In: Arnett, R. H., Jr & M. C. Thomas (eds) American Beetles vol. 1. Archostemata, Myxophaga, Adephaga, Polyphaga: Staphyliniformia pp. 156–186. CRC Press: Boca Raton.
[S86] Spangler, P. J. 1986. Insecta: Coleoptera. In: Botosaneanu, L. (ed.) Stygofauna Mundi: A Faunistic, Distributional, and Ecological Synthesis of the World Fauna inhabiting Subterranean Waters (including the Marine Interstitial) pp. 622–631. E. J. Brill/Dr W. Backhuys: Leiden.
[VB21] Vasilikopoulos, A., M. Balke, S. Kukowka, J. M. Pflug, S. Martin, K. Meusemann, L. Hendrich, C. Mayer, D. R. Maddison, O. Niehuis, R. G. Beutel & B. Misof. 2021. Phylogenomic analyses clarify the pattern of evolution of Adephaga (Coleoptera) and highlight phylogenetic artefacts due to model misspecification and excessive data trimming. Systematic Entomology 46: 991–1018.
Watts, C. H. S. 1978. A revision of the Australian Dytiscidae. Australian Journal of Zoology, Supplementary Series 57: 1–166.
[WM13] Watts, C. H. S., & J. McRae. 2013. Limbodessus bennetti sp. nov., the first stygobitic Dytiscidae (Coleoptera) from the Pilbara region of Western Australia. Records of the Western Australian Museum 28 (2): 141–143.