Microchaetidae, Beddard, 1895

Key to genera of Microchaetidae View in CoL View at ENA (s.str.)

1 Proandric (male funnels in 10). Holoic, with V-shaped nephridial bladders. Variably sized, from small to large ( 60–500 mm). Segment number 80–450 .. Proandricus View in CoL

– Holandric or metandric (male funnels in 10 and 11, or only in 11).......................2

2 Holandric or metandric (male funnels in 10 and 11, or only in 11); dorsal blood vessel simple throughout the whole body length; excretory system holoic with J-shaped nephridial bladders. Medium-sized ( 60–250 mm). Segment number 180–450....... ............................................................................................................ Kazimierzus View in CoL

– Holandric (male funnels in 10 and 11); dorsal blood vessel double in certain preclitellar segments, simple when crossing septa; excretory system holoic, with large or medium-sized, tightly coiled loops and elongated, V-shaped nephridial bladders .. ................................................................................................................................3

3 Coiled nephridial loops bushy, very large, V-shaped nephridial bladders widely open. Spermathecae always located posterior to testis, multiple in all or in some of the segments. Very large ( 550–2600 mm). Segment number usually over 500, may exceed 1200...................................................................................... Microchaetus View in CoL

– Small, bushy loops of holoic nephridia, with V-shaped nephridial bladders. Spermathecae located anterior or posterior to testis, or in testicular segments. Mature individuals small or medium-sized, not reaching 500 mm, with the segment number between 100 and 500................................................................................ Geogenia View in CoL