Bryaxis bulbifer, copyright Udo Schmidt.

Belongs within: Pselaphinae.

Bryaxis on the prowl
Published 7 December 2012
Pselaphine, probably Bryaxis bulbifer, photographed by Krister Hall.

Bryaxis is a large genus, with over 400 described species and subspecies (Hlaváč 2008), of small beetles belonging to the group known as the Pselaphinae, a subgroup of the Staphylinidae. In older references, you’ll see the pselaphines referred to as a separate family Pselaphidae from the staphylinids, but most authors now include it in the latter as it has become clear that the pselaphines are not only related to the staphylinids but nested well within them. It is not so surprising that this was not immediately recognised: your average staphylinid looks something like this:

Paederus riparius, from here.

Bryaxis species are mostly found living in leaf litter, where they are predators of other micro-arthropods such as springtails. If you look at the top photo, you will be see two appendages with paddle-shaped endings attached to the head just behind the antennae. These are the maxillary palps, often enlarged in pselaphines (sometimes ridiculously so). Glands on the inside of the palp ‘paddle’ produce a sticky secretion, and the palps are used to grab the prey when hunting. The process of prey capture in Bryaxis puncticollis was illustrated by Schomann et al. (2008):

Prey detected!
Palps at the ready…
The final parts of the process. The springtail is held tail-upwards so that it can’t escape or injure the beetle using the forked furca, the ‘spring’ underneath its abdomen.

As befits a large genus, Bryaxis has a truly headache-inducing taxonomic history, summarised by Besuchet (1966). The genus was first named by Kugelann in 1794. Kugelann’s work can’t have been that widely publicised, however, because in 1817 Leach gave the name Bryaxis to a different genus of pselaphine. Most subsequent authors used Bryaxis in the sense of Leach, and included Kugelann’s original Bryaxis in the genus Bythinus, until this was corrected by Raffray in 1904. Raffray treated Bythinus as a junior synonym of Kugelann’s Bryaxis, and placed Leach’s ‘Bryaxis‘ under the name Rybaxis. Even so, some European authors persisted in using Leach’s Bryaxis.

It wasn’t until the 1950s and 1960s that the usage of Bryaxis became stabilised, but there was one further wrinkle to the story. When Raffray identified Bythinus as a synonym of the true Bryaxis, he separated out a few previous Bythinus species as a new genus Bolbobythus. However, one of those was the type species of Bythinus. So, as finally laid out by Besuchet (1966): what had been called ‘Bolbobythus‘ was really Bythinus, ‘Bythinus‘ was really Bryaxis, and ‘Bryaxis‘ was really Rybaxis! What could be simpler?

Systematics of Bryaxis
<==Bryaxis Kugelann 1794 [incl. Arcopagus Leach 1817, Bythinus Leach 1817, Kunzea Leach 1826]R04a
    |--B. abastumana Reitter 1880R04a
    |--B. abeillei Guilleb. 1888R04a
    |--B. aelistae Reitter 1881R04a
    |--B. affinis Sharp 1883R04a
    |--B. algirica Raffray 1871 [=Machaerites algiricus]R04a
    |--B. alpestris Dodero 1900R04a
    |--B. amasiae Reitter 1890R04a
    |--B. ammonR04a
    |--B. anatolicaR04a
    |--B. anguliceps Reitter 1885R04a
    |--B. antonii Croissand. 1891R04a
    |--B. apfelbecki Ganglbauer 1895 [incl. B. czernohorshyi Reitter 1902]R04a
    |--B. appendiculata Reitter 1884R04a
    |--B. argiola Reitter 1888R04a
    |--B. argodi Croiss. 1885R04a
    |--B. armata (Schaufuss 1863) [=Machaerites armata]R04a
    |--B. armipes Reitter 1881R04a
    |--B. asturiensis Reitter 1879 [incl. B. sharpi Saulcy in Reitter 1881 non Broun 1880]R04a
    |--B. attila Saulcy 1878R04a
    |--B. bajulus Hampe 1863R04a
    |--B. baudueri Reitter 1881R04a
    |--B. bosnica Ganglbauer 1895R04a
    |--B. brusinae Reitter 1879R04a
    |--B. bulbifer (see below for synonymy)R04a
    |--B. carinula Rey 1888R04a
    |--B. carolinae Casey 1897R04a
    |--B. carpathica Saulcy 1875R04a
    |--B. cateniger Krauss 1899 [incl. B. anabates Holdhaus 1902, B. incerta Dodero in Raffray 1904 (n. n.)]R04a
    |--B. caviceps Reitter 1881R04a
    |--B. clavicornis (see below for synonymy)R04a
    |--B. clavipes Motsch. 1851 (see below for synonymy)R04a
    |--B. cocles Saulcy 1863 [incl. B. hypogaea Saulcy 1863]R04a
    |--B. collaris Baudi 1859 [incl. B. germana, B. manueli Sharp 1874]R04a
    |--B. convexa Kiesenw. 1858 [incl. B. brenskei Reitter 1884, B. levantina Schaufuss 1882]R04a
    |--B. corcyrea Reitter 1884R04a
    |--B. corpulenta Motsch. 1845 [incl. B. jaso Saulcy 1878]R04a
    |--B. crassicornis Motsch. 1835 (see below for synonymy)R04a
    |--B. croissandeaui Pic 1892R04a
    |--B. curtisi Leach 1817 (see below for synonymy)R04a
    |--B. dalmatina Reitter 1881R04a
    |--B. damryi (Croissandeau 1891) [=Machaerites damryi]R04a
    |--B. dentimana (Reitter 1884) [=Machaerites dentimanus]R04a
    |--B. desbrochersi Croiss. 1891R04a
    |--B. dichroa Reitter 1881R04a
    |--B. difficilis Reitter 1884R04a
    |--B. diversicornis Raffray 1873 (see below for synonymy)R04a
    |--B. elephas Reitter 1879R04a
    |--B. erichsoni [incl. B. erichsoni var. ursus Reitter 1881]R04a
    |--B. etrusca Reitter 1881R04a [incl. Br. etrusca var. pedator Reitter 1881R04a, Bythinus pedatorA89]
    |--B. fauconneti Fauvel 1886 [incl. B. fauconneti var. grilati Reitter 1886]R04a
    |--B. femorata Aubé 1844R04a
    |--B. formanecki Fleischer 1901R04a
    |--B. frivaldskyi Reitter 1887R04a
    |--B. gallica Reitter 1887R04a
    |--B. giraffa Reitter 1879R04a
    |--B. glabrata Rye 1870R04a
    |--B. gladiator Reitt. 1884R04a
    |--B. grouvellei Reitter 1881 (see below for synonymy)R04a
    |--B. halbherri Reitter 1885R04a
    |--B. harti Blackb. 1891M96
    |--B. heydeni Reitter 1879R04a
    |--B. hyalinaM96
    |--B. iberica Saulcy 1870R04a
    |--B. islamita Reitter 1885R04a
    |--B. italica Baudi 1869R04a
    |--B. japonica Sharp 1874R04a
    |--B. judaea Pic 1900R04a
    |--B. koltzei Reitter 1887R04a
    |--B. koziorowiczi (Croissand 1891) [=Machaerites koziorowiczi]R04a
    |--B. lagari [incl. B. lictor Flach 1891]R04a
    |--B. latebrosa Reitter 1884 (see below for synonymy)R04a
    |--B. lederi Reitter 1888 [incl. B. lederi var. fluctuosa Reitter 1888]R04a
    |--B. leonhardi Reitter 1902R04a
    |--B. lindensis Blackb. 1891M96
    |--B. longula [incl. B. longula var. carniolica Reitter 1881]R04a
    |--B. ludyi (Reitter 1881) (see below for synonymy)R04a
    |--B. lusitanica Saulcy 1870 (see below for synonymy)R04a
    |--B. melinensis Reitter 1881R04a
    |--B. montivaga Reitter 1884R04a
    |--B. mulsanti Kiesenw. 1850 [incl. B. massanae Saulcy 1864]R04a
    |--B. muscorumR04a
    |--B. myrmido (Reitter 1881) [=Machaerites myrmido]R04a
    |--B. nakeralae Reitt. 1884R04a
    |--B. nasicornis Saulcy 1870R04a
    |--B. nemilensis Reitter 1885R04a
    |--B. nigripennis Aubé 1844R04a
    |--B. nodicornis Aubé 1833 [incl. B. nodicornis var. montandoni Raffray 1904, B. sternbergi Schmidt 1836]R04a
    |--B. oedymera Ganglb. 1895R04a
    |--B. oertzeni Reitter 1881R04a
    |--B. oranensis Pic 1896R04a
    |--B. ovensensis Blackb. 1891M96
    |--B. pandellei Saulcy 1863 [incl. B. curticollis Reitter 1879]R04a
    |--B. pastoralis Peyerim. 1901R04a
    |--B. pauper Kiesenw. 1858R04a
    |--B. paupercula Reitter 1885R04a
    |--B. peloponnesia Reitter 1884R04a
    |--B. peninsularis Saulcy 1870R04a
    |--B. picteti Tournier 1859 [incl. B. marthae Reitter 1881]R04a
    |--B. porsenna Reitter 1881R04a
    |--B. portalegrensis Schaufuss 1882R04a
    |--B. puncticollis Denny 1825 [incl. B. chevrolati Aubé 1833, B. regularis, B. rugicollis]R04a
    |--B. pyrenaea Saulcy 1863 [incl. B. pyrenaea var. normanna Saulcy in Croiss. 1891]R04a
    |--B. raveli Pic 1902R04a
    |--B. reitteri Saulcy 1875R04a
    |--B. reversa Sharp 1883R04a
    |--B. rosti Reitter 1894R04a
    |--B. rostrata Motsch. 1845 [incl. B. murida Saulcy 1878]R04a
    |--B. ruthena Saulcy 1876R04a
    |--B. scapularis (Reitter 1881) [=Machaerites scapularis]R04a
    |--B. sculpticornis Guilleb. 1891R04a
    |--B. sculptifrons Reitter 1879 [incl. B. sculptifrons var. roumaniae Raffray 1904]R04a
    |--B. serripes Fauvel 181R04a
    |--B. simoni Reitter 1879 [incl. B. simoni var. bulgarica Reitter 1879]R04a
    |--B. simplex Baudi 1869R04a
    |--B. solida Reitter 1881R04a
    |--B. splendida Croiss. 1891R04a
    |--B. steindachneri Reitter 1880R04a
    |--B. stussineri Reitter 1881R04a
    |--B. subseriata Weise 1877R04a
    |--B. subsolida Reitter 1902R04a
    |--B. swanetica Reitter 1884R04a
    |--B. tcherkessica Reitter 1888 [incl. B. tcherkessica var. inermis Reitter 1888]R04a
    |--B. theana Reitter 1894R04a
    |--B. theryi (Guilleb. 1893) [=Machaerites theryi]R04a
    |--B. transsilvanica Ganglbauer 1897R04a
    |--B. troglocera Saulcy 1870R04a
    |--B. tunisea Pic 1900R04a
    |--B. tychoides (Brendel 1863) [=Tychus tychoides; incl. Machaerodes bythinoides Brendel 1890]R04a
    |--B. valida Aubé 1844R04a
    |--B. verrucula Reitter 1881R04a
    |--B. viertli Reitter 1881R04a
    |--B. weisei Saulcy 1875R04a
    `--B. xambeui Guilleb. 1888R04a
Nomina nuda: Bryaxis castanoptera Motschulsky 1851R04b
             Bryaxis consanguinea Motschulsky 1855R04b
             Bryaxis cornigera Motschulsky 1855R04b
             Bryaxis corniventris Motschulsky 1856R04b
             Bryaxis curvicera Motschulsky 1853R04b
             Bryaxis decorata Motschulsky 1851R04b
             Bryaxis dilatata Motschulsky 1851R04b
             Bryaxis extensa Motschulsky 1851R04b
             Bryaxis glabrella Motschulsky 1854R04b
             Bryaxis indistincta Motschulsky 1851R04b
             Bryaxis lata Motschulsky 1851R04b
             Bryaxis macrura Motschulsky 1855R04b
             Bryaxis nitida Motschulsky 1855R04b
             Bryaxis pilifera Motschulsky 1851R04b
             Bryaxis suturella Motschulsky 1851R04b
             Bythinus pedestris Motschulsky 1845R04b

Bryaxis bulbifer [incl. B. anomala, B. cephalotes Motsch. 1845, B. bulbifer var. extremitalis Reitter 1878, B. flavipalpis Motsch. in Raffray 1904 (n. n.), B. glabicollis, B. schneideri Kugel. 1794, B. taurica Motsch. 1851]R04a

Bryaxis clavicornis [incl. B. glabricollis, B. clavicornis var. inflatipes Reitter 1884, B. laevicollis Fairmaire 1857 non Aubé 1844, B. nigrina Mulsant & Rey 1861]R04a

Bryaxis clavipes Motsch. 1851 [incl. B. dimorpha Reitter 1888, B. clavipes var. martkopia Reitter 1880, B. schamyliana Saulcy 1878]R04a

Bryaxis crassicornis Motsch. 1835 [incl. B. chaudoiri Chaudoir 1815 R04, B. longipalpis Motsch. 1835, B. crassicornis var. quisquiliarum]R04a

Bryaxis curtisi Leach 1817 [incl. B. clavicornis Denny 1825 (preoc.), B. curtisiana Leach 1826, B. curtisi var. hungarica Reitter 1881]R04a

Bryaxis diversicornis Raffray 1873 [incl. B. foveicornis Guilleb. 1897, B. mauricii Reitter 1894, B. diversicornis var. pallidior Pic 1900]R04a

Bryaxis grouvellei Reitter 1881 [incl. B. grouvellei var. alticola Dodero 1900, B. grouvellei var. obscurans Pic 1893, B. grouvellei var. sculpticollis Reitter 1885]R04a

Bryaxis latebrosa Reitter 1884 [incl. B. latebrosa var. ravouxi Grilat 1889, B. latebrosa var. schneideri Reitter 1890 non B. schneideri Kugel. 1794, B. baudueri var. spissipes Croissand. 1891]R04a

Bryaxis ludyi (Reitter 1881) [=Machaerites ludyi; incl. B. curvicornis Croissand 1891, M. eppelshemi Reitter 1884, B. falesiae Fauvel 1883]R04a

Bryaxis lusitanica Saulcy 1870 [incl. B. crotchi Sharp 1874, B. ehlersi, B. monstripes Reitter 1879, B. oedipus Sharp 1874 (preoc.)]R04a

*Type species of generic name indicated


[A89] Argod, A. 1889. Communications suivantes. Annales de la Société Entomologique de France, 6e série 9: cxvii.

Besuchet, C. 1966. Bryaxis Kugelann, 1794 and Bythinus Leach 1817 (Insecta, Coleoptera): proposed addition to the Official List in their original sense. Bulletin of Zoological Nomenclature 23 (2–3): 114–116.

Hlaváč, P. 2008. A new cavernicolous species of the genus Bryaxis (Coleoptera: Staphylinidae: Pselaphinae) from the island of Mljet. Natura Croatica 17 (1): 1–8.

[M96] Masters, G. 1896. Catalogue of the described Coleoptera of Australia. Supplement, part II. Dytiscidae, Gyrinidae, Hydrophyllidae, Staphylinidae, Pselaphidae, Paussidae, Silphidae, Scaphididae, Histeridae, Phalacridae, Nitidulidae, Trogositidae, Colydiidae, Cucujidae, Cryptophagidae, Lathridiidae, Mycetophagidae, Dermestidae, Byrrhidae, Parnidae, Heteroceridae. Proceedings of the Linnean Society of New South Wales 21 (Suppl.): 695–754.

[R04a] Raffray, A. 1904a. Genera et catalogue des psélaphides [part II]. Annales de la Société Entomologique de France 73: 1–400.

[R04b] Raffray, A. 1904b. Genera et catalogue des psélaphides [part III]. Annales de la Société Entomologique de France 73: 401–476, pls 1–3.

Schomann, A., K. Afflerbach & O. Betz. 2008. Predatory behaviour of some Central European pselaphine beetles (Coleoptera: Staphylinidae: Pselaphinae) with descriptions of relevant morphological features of their heads. European Journal of Entomology 105: 889–907.

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