Bythinini
Raffray, 1890
small short-winged mould beetles
Genus Guides
3Bythinini is a tribe of small, short-winged rove beetles established by Achille Raffray in 1890. The tribe comprises over 600 across approximately 30 , distributed primarily in the Holarctic region. Members are characterized by distinctive maxillary palpus structure and reduced hind claws. The tribe is divided into three subtribes—Bythinina, Machaeritina, and Xenobythina—though the status of the latter two remains debated. Many species inhabit forest litter, soil, caves, and moist microhabitats.
Pronunciation
How to pronounce Bythinini: //bɪˈθaɪnɪnaɪ//
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Identification
Bythinini can be distinguished from other pselaphine tribes by the combination of: short third maxillary palpal segment with elongated and swollen fourth segment; presence of oculo-mandibular carina; first visible sternite subequal to second in midline length; and reduced hind tarsal claws. The elongated first antennal segment and often projecting rostrum provide additional diagnostic characters. Within Goniaceritae, these features collectively separate Bythinini from related tribes.
Images
Habitat
Forest litter, soil, caves, mosses, and riparian zones near streams or springs. The subtribe Machaeritina is primarily composed of cave-dwelling .
Distribution
Primarily Holarctic. -level distribution includes: Europe (Bythinus, Antrobythus, Bythoxenus, Machaerites, Spelaeobythus), North America (Machaerodes, Speleochus), Japan (Bythoxenites), and various Balkan endemics (Biokovobythus, Grguria, Melledobythus, Nonveilleria, Pauperobythus, Velebythus).
Similar Taxa
- Other Goniaceritae tribesBythinini shares the supertribe Goniaceritae with other pselaphine tribes, but is distinguished by the unique maxillary palpus structure (short third segment, swollen fourth) and reduced hind tarsal claws.
- Non-pselaphine StaphylinidaeBythinini and other Pselaphinae are distinguished from most rove beetles by their compact body form, clubbed , and specialized mouthpart structures associated with on microarthropods.
More Details
Systematic subdivisions
The tribe contains three subtribes: Bythinina (the nominate subtribe with ~400 in Bryaxis alone), Machaeritina (primarily cave-dwelling, status debated), and Xenobythina (status debated). Multiple remain incertae sedis due to uncertain subtribal placement.
Fossil record
Two extinct , †Boreotethys and †Ceratobythus, are known from Cretaceous Burmese amber, indicating the tribe's ancient origin.
Taxonomic history
Established by Raffray in 1890, the tribe has undergone significant revision. The subtribes Machaeritina and Xenobythina were proposed by Jeannel in 1950, but their monophyly and validity remain subjects of debate.