Megadytes latus, photographed by Wolfgang Walz Hillermann.

Belongs within: Dytiscidae.
Contains: Hydaticus, Aciliini.

The Dytiscinae are a large clade of diving beetles. With the exception of the basal Cybistrini, males of the Dytiscinae have the pro- and mesotarsomeres broadly expanded with ventral sucker-like setae, used to grip the female during mating. In a number of subsequent lineages, females have conversely evolved ornamented elytra that may reduce the effectiveness of such gripping setae (Miller 2003). Members of the tribes Cybistrini and Dytiscini have knife-like gonocoxae that they use to insert eggs into plant tissue. Other tribes have long, blunt gonocoxae and lay eggs in cracks in wood, moss or other cryptic positions (Miller 2001).

The Cybistrini are united by a number of features including a small apicoventral region of very stiff setae on the elytra, a dorsal series of natatory setae on the metafemur, a relatively large cluster of setae at the apicodorsal angle of the metatibia, and an anterior metatibial spur that is acuminate and distinctly broader basally than the posterior spur (Miller 2001).

Chracters (from Miller 2001): Anterolateral margin of eye evenly rounded; female genitalia of dytiscine type, with bursa absent and spermatophore placed in membranous pouch ventrad of gonocoxae; gonocoxae strongly fused dorsally; median lobe bilaterally symmetrical; larvae with fringe of fine setae along last abdominal segments.

    |--Cybistrini M03
    |    |  i. s.: Regimbartina pruinosa M01
    |    |--+--Spencerhydrus Sharp 1882 M03, LM87
    |    |  |    |--*S. latecinctus Sharp 1882 [incl. S. semiflavus Sharp 1882] LM87
    |    |  |    `--S. pulchellus Sharp 1882 LM87
    |    |  `--+--Austrodytes Watts 1978 M01, LM87
    |    |     |    `--*A. insularis (Hope 1842) [=Cybister insularis] LM87
    |    |     `--Onychohydrus M03
    |    |          |--O. (Onychohydrus) M01
    |    |          |    |--O. (O.) hookeri M01
    |    |          |    `--O. (O.) scutellaris M01
    |    |          `--O. (Sternhydrus) atratus M01
    |    `--+--Megadytes M03
    |       |    |  i. s.: M. aeneus Ormancey 1843 R89
    |       |    |         M. fallax R89
    |       |    |         M. puncticollis R89
    |       |    |--M. (Bifurcitus) giganteus M01
    |       |    `--+--M. (Paramegadytes) glaucus M01
    |       |       `--M. (Megadytes) M01
    |       |            |--M. (M.) fraternus M01
    |       |            |--M. (M.) laevigatus M01
    |       |            |--M. (M.) latus M01
    |       |            `--M. (M.) marginithorax M01
    |       `--Cybister Curtis 1827 M03, LM87
    |            |  i. s.: *C. virens (Müller 1776) [=Dytiscus virens] LM87
    |            |         C. cephalotes G89
    |            |         C. godeffroyi (Wehncke 1876) [=Trogus godeffroyi; incl. C. simoni Régimbart 1877] LM87
    |            |         C. loxidiscus Wilke 1919 LM87
    |            |         C. yulensis Guignot 1956 LM87
    |            |--C. marginicollis M01
    |            |--+--C. ellipticus M01
    |            |  `--C. fimbriolatus M01
    |            `--+--C. puncticollis M01
    |               `--C. tripunctatus (Olivier 1795) M01, LM87 (see below for synonymy)
    |                    |--C. t. tripunctatus I92
    |                    `--C. t. orientalis Gschwendtner 1931 I92
    `--+--+--Hyderodes Hope 1838 M03, LM87 [Hyderodini]
       |  |    |--*H. shuckardi Hope 1838 LM87
       |  |    `--H. crassus Sharp 1882 [incl. H. collaris Sharp 1882] LM87
       |  `--+--Hydaticus M03
       |     `--+--+--Aciliini M03
       |        |  `--Notaticus [Aubehydrinae, Aubehydrini] M03
       |        |       `--N. fasciatus M03
       |        `--Eretes Castelnau 1832 M03, LM87 [Eretini]
       |             |--*E. stictus (Linnaeus 1767) [=Dytiscus stictus] LM87
       |             |--E. australis (Erichson 1842) [=Eunectes australis; incl. Eu. punctipennis Macleay 1871] LM87
       |             |--E. explicitus B14
       |             `--E. griseus M03
       `--Dytiscus Linnaeus 1758 [Dytiscini] M01
            |--D. alaskanus M01
            |--D. caraboides Linnaeus 1758 L58
            |--D. cinereus Linnaeus 1758 L58
            |--D. cordieri M01
            |--D. dauricus M01
            |--D. delictus Zaitsev 1906 I92
            |--D. erytrocephalus Linnaeus 1758 L58
            |--D. fasciventris M03
            |--D. flavocinctus B35
            |--D. fuscipes Linnaeus 1758 L58
            |--D. fuscus Linnaeus 1758 L58
            |--D. hermanni [=Hydrachne hermanni] L02
            |--D. latissimus Linnaeus 1758 L58
            |--D. maculatus Linnaeus 1758 L58
            |--D. marginalis Linnaeus 1758 B14 [incl. D. marginalis var. conformis C01]
            |--D. marginicollis M01
            |--D. palustris L02
            |--D. persicus B14
            |--D. piceus Linnaeus 1758 L58
            |--D. scarabaeoides Linnaeus 1758 L58
            |--D. semistriatus Linnaeus 1758 L58
            |--D. sexpustulatus L02
            |--D. sharpi Wehncke 1875 I92
            |--D. striatus Linnaeus 1758 L58
            |--D. sulcatus Linnaeus 1758 L58
            `--D. verticalis M03

Cybister tripunctatus (Olivier 1795) M01, LM87 [=Dytiscus tripunctatus LM87; incl. C. gayndahensis Macleay 1871 LM87, C. granulatus Blackburn 1888 LM87]

*Type species of generic name indicated


[B35] Boisduval, J. B. 1835. Voyage de Découvertes de l’Astrolabe. Exécuté par ordre du Roi, pendant les années 1826–1827–1828–1829, sous le commandement de M. J. Dumont d'Urville. Faune entomologique de l'océan Pacifique, avec l'illustration des insectes nouveaux recueillis pendant le voyage vol. 2. Coléoptères et autres ordres. J. Tastu: Paris.

[B14] Bouchard, P. (ed.) 2014. The Book of Beetles: A lifesize guide to six hundred of nature's gems. Ivy Press: Lewes (United Kingdom).

[C01] Csiki, E. 1901. Bogarak [Coleopteren]. In: Horváth, G. (ed.) Zichy Jenő Gróf Harmadik Ázsiai Utazása [Dritte Asiatische Forschungsreise des Grafen Eugen Zichy] vol. 2. Zichy Jenő Gróf Harmadik Ázsiai Utazásának Állattani Eredményei [Zoologische Ergebnisse der Dritten Asiatischen Forschungsreise des Grafen Eugen Zichy] pp. 75–120. Victor Hornyánszky: Budapest, and Karl W. Hierseman: Leipzig.

[G89] Gestro, R. 1889. Viaggio ab Assab nel Mar Rosso dei signori G. Doria ed O. Beccari con il R. Avviso «Esploratore» dal 16 Novembre 1879 al 26 Febbraio 1880.—IV. Coleotteri. Annali del Museo Civico di Storia Naturale di Genova, Serie 2a, 7: 5–72.

[I92] Iwahashi, J. (ed.) 1992. Reddo Deeta Animaruzu: a pictorial of Japanese fauna facing extinction. JICC: Tokyo.

[L02] Latreille, P. A. 1802. Histoire Naturelle, générale et particulière des crustacés et des insectes vol. 3. Familles naturelles des genres. F. Dufart: Paris.

[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.

[L58] Linnaeus, C. 1758. Systema Naturae per Regna Tria Naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata. Laurentii Salvii: Holmiae.

[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.

[M03] Miller, K. B. 2003. The phylogeny of diving beetles (Coleoptera: Dytiscidae) and the evolution of sexual conflict. Biological Journal of the Linnaean Society 79: 359–388.

[R89] Régimbart, M. 1889. Enumération des Haliplidae, Dytiscidae et Gyrinidae recueillis par M.r le Prof. L. Balzan dans l’Amérique méridionale et description de quelques autres espèces voisines. Annali del Museo Civico di Storia Naturale di Genova, Serie 2a, 7: 256–268.

Last updated: 5 February 2018.

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