Sperchon and Sperchonopsis are the 2 genus of the family Sperchontidae. Here I will pick up the description and the key to species given by Soar & Williamson (1925).
Description of the genus Sperchon.
- Skin reticulate, aciculate or ridged, with or without chitinous plates embedded.
- Median eye present or wanting.
- Capitulum capable of some movement.
- Palpi strong, porose, second segment with a conical pointed process on the flexor surface; fourth segment with two small chitinous processes one behind the other also on the flexor surface.
- Fourth pair of epimera quadrilateral, narrowed posteriorly.
- Legs usually with short spines.
- Genital area between the posterior groups of epimera with three acetabula along each side of genital aperture.
Two subgenera
- Sperchon (Squasmosperchon Sig Thor) Wolcott.
- Hispidosperchon Sig Thor.
Key to species of Sperchon.
1. Dorsal surface almost entirely covered with a chitinous plate =>2.
– Dorsal surface whithout chitinous plate => 3.
2. (1) Dermal glands small, inconspicuous => Sperchon clupeifer.
– Dermal glands large and prominents => Sperchon thienemanni.
3. (1) Body skin more or less papillated =>4.
– Body skin more or less reticulated => 9.
4. (3) With the firs pair of epimera connected behind the capitulum with a chitinous band =>5
– With the first pair of epimera not connected behind the capitulum =>7.
5. (4) With the two processes on the flexor edge of the fourth segment of epimera small, not swelling out the marginal line =>6.
– With the two processes prominents and swelling out the marginal line => Sperchon glandulosus.
6. (5) With a short hair between the two processes on the fourth segment, and one in the middle of the flexor surface of third => Sperchon brevirostris.
– Without a short hair between the two processes on fourth segment => Sperchon brevirostris V. pachydermis.
7. (4) With small dermal glands => Sperchon papillosus.
– With large and prominent dermal glands => 8.
8. (7) With palpi thick and robust, with two processes on fourth segment dividing the flexor surface into three equal parts => Sperchon longirostris.
– With the second processes on fourth segment near distal end. The other process near middle of flexor surface => Sperchon squamosus.
9. (3) With epimera and genital area occupying about one-third anterior ventral surface => Sperchon tenuabilis.
– With epimera and genital area occupying more than one-third => 10.
10. (9) Palpi with two strong bristles on flexor surface of third segment of palpi => Sperchon denticulatus.
– Palpi without teeth => 11.
11. (10) With two strong bristles on flexor surface of third segment of palpi => 12
– Without bristles on flexor edge of third segment of palpi => Sperchon undulosus.
12. (11) With two strong bristles at distal end of third segment of palpi => Sperchon mirus.
– With two strong bristles near centre of third segment of palpi => Sperchon setiger.
References.
- Soar, C. & Williamson, W. (1925): The British hydracarina. Ray Society. Volume I. Pages 98-99.
Sperchon glandulosus - Piersig - Deutschland Hydrachniden - 1897 - p595 - Fig54
