Tylobolus
Cook, 1904
Species Guides
2- Tylobolus claremontus
- Tylobolus uncigerus(Black Round Millipede)
Tylobolus is a of medium to large millipedes in the Spirobolidae, to western North America. The genus comprises seven recognized ranging from Washington to Baja California, with most species occupying restricted ranges along the Pacific Slope. Tylobolus serves as the type genus for the Tylobolinae and is considered morphologically advanced within its family due to complex genital structures and distinctive male leg modifications. Females attain larger body sizes than males, a common pattern in the group.
Pronunciation
How to pronounce Tylobolus: /taɪˈloʊbələs/
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Identification
Distinguished from other Spirobolidae by the combination of: widely separated with more than twice the patch width between them; smooth or very fine body ring texture; and in males, the hooked projection on the third leg pair. The Hiltonius, the only other member of Tylobolinae, occurs in Southern California and Mexico and lacks these advanced genital features. Separation from Spirobolinae genera requires examination of genital .
Images
Appearance
Cylindrical or nearly cylindrical body form with smooth or finely textured body rings. possess 40 to 54 segments. Body length ranges from 36–92 mm and width from 5–10 mm. Coloration varies from black to reddish brown, with margins of rings sometimes marked in red or yellow. consist of widely separated ocular patches, each containing 27–50 ocelli, with interocular distance exceeding twice the width of a single patch.
Habitat
Occupies diverse environments across western North America including coastal regions, chaparral, and desert . One , T. utahensis, occurs in the Mojave Desert east of the Sierra Nevada; all others are restricted to the Pacific Slope.
Distribution
to western North America. Range extends from Washington state (north of the Columbia River) south to northern Baja California, Mexico. generally have small, non-overlapping geographic ranges. Documented presence in Arizona, California, Baja California, Nevada, and Oregon.
Ecological Role
Functions as a in forest floor and soil . Specific ecological contributions remain undocumented.
Similar Taxa
- HiltoniusOnly other in Tylobolinae; distinguished by less complex genital and absence of the hooked third leg projection in males. Geographic range partially overlaps in Southern California.
- Narceus americanusEastern North American spirobolid previously confused with the dubious 'T. fredericksoni'; no verified overlap in range with Tylobolus.
Misconceptions
The 'Tylobolus fredericksoni' was erroneously reported from Kansas and Nebraska based on fragmented, equivocal specimens from 1949. No specimens have been collected since, and the species is now considered a , likely representing misidentified Narceus americanus rather than a genuine Tylobolus species.
More Details
Evolutionary significance
Tylobolus is considered one of the most morphologically advanced in Spirobolidae, with features absent or poorly developed in other genera. The Tylobolinae (Tylobolus + Hiltonius) is thought to be more derived than Spirobolinae, though the Spirobolidae itself is considered the most primitive family of Spirobolida.