Gosodesmus claremontus

Distinguished from other California millipedes by combination of: (1) flattened, ribbon-like body shape characteristic of order Platydesmida; (2) pink to coral coloration; (3) small size under 30 mm; (4) high segment count (up to 81). Similar pink-colored millipedes in family Xystodesmidae (e.g., Harpaphe, Boraria) have cylindrical bodies and differ in segment number and paranotal structure. Other platydesmids in California (if present) would require examination of gonopod morphology for definitive separation.

Flattened, ribbon-like body with variable pink to coral base coloration. Some individuals display a black or purple dorsal stripe running the length of the body. Body length 17–27 mm with up to 81 segments. The platydesmidan body form is distinctly broad and low compared to cylindrical millipedes.

Occurs in mesic forest environments including coastal redwood forests, mixed evergreen woodlands, and montane coniferous forests. Found in the Coast Ranges and Sierra Nevada. Specific microhabitat preferences include decaying wood, leaf litter, and moist soil layers. Elevation range spans from near sea level to montane zones.

Endemic to California, United States. Documented from the Coast Ranges (including northern and central coastal counties) and the Sierra Nevada. Absent from desert regions and the Central Valley.

Activity patterns poorly documented; observations span multiple months suggesting year-round presence in suitable microhabitats. Surface activity likely increases during moist conditions following rainfall.

Slow-moving, burrowing millipede typically found in decaying woody debris and moist soil. When disturbed, exhibits coiling behavior typical of many millipedes. No defensive secretions documented for this species, though related platydesmids are not known to produce benzoquinones characteristic of many other millipede orders.

Contributes to decomposition of woody plant material and nutrient cycling in forest ecosystems. Serves as prey for small vertebrates and invertebrates in forest floor food webs.

Frequently photographed and shared on citizen science platforms due to striking coloration; among the most recognizable California millipedes for naturalists. No documented economic importance or pest status.

• Harpaphe haydeniana (Yellow-spotted Millipede)Overlaps in California coastal forests and shares bright aposematic coloration, but has cylindrical body, larger size (up to 60 mm), and distinct yellow spots on black background rather than uniform pink.
• Boraria strictaSimilar pink coloration and California distribution, but cylindrical xystodesmid body form, larger size, and different segment/paranotal structure.
• Other PlatydesmidaShare flattened body form but require examination of male gonopods or detailed segment counts for definitive identification; geographic separation may apply for non-California species.

• California endemic
• aposematic coloration
• forest floor
• decomposer
• citizen science flagship

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life