Polydesmidae
flat-backed millipedes, tractor millipedes
Genus Guides
3- Polydesmus
- Pseudopolydesmus(Pink Flat-backs)
- Scytonotus
Polydesmidae is a of millipedes in the order Polydesmida comprising over 240 across more than 30 . These millipedes are characterized by their flattened, plate-like that give them the "flat-backed millipedes." They range from 4 mm to 30 mm in length and display coloration from black through brownish to pallid, rarely vivid. The family has a predominantly Holarctic distribution extending to Mexico, North Africa, and Java, with highest diversity in the Mediterranean region. Several species exhibit notable biological traits, including in segment number and chemical defense secretions.
Pronunciation
How to pronounce Polydesmidae: /ˌpɒlɪˈdɛzmɪdiː/
These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.
Identification
Distinguished from other by well-developed, dentate lateral paranota and flattened plates. The combination of small transverse oval collum with smooth margin and simple paranota separates Polydesmidae from related families within Polydesmida. Two pairs of legs per body segment distinguishes millipedes from centipedes (one pair per segment).
Images
Habitat
Forest including woodlots and tropical rainforests; forest floor and leaf litter. Some are cavernicolous (cave-dwelling), including multiple Epanerchodus species in southern China.
Distribution
Mostly Holarctic distribution extending south to Mexico, North Africa, and Java; highest in Mediterranean region. Documented from Caucasus region, continental China, Altai region of Russia, Michigan (USA), and Rica. GBIF records from Colombia, Denmark, Norway, Sweden, and Vermont (USA).
Diet
Decaying plant material; rotting organic matter on forest floor
Behavior
Curls into tight ball when threatened, protecting surface with sturdy and lateral plates. Locomotion achieved through synchronized waves of dozens of legs. Guided by simple , touch, and smell in foraging.
Ecological Role
Decomposer and recycler of vegetation; breaks down plant material, making energy and nutrients available to other organisms in forest . Described as "essential" in rainforest for nutrient cycling.
Human Relevance
Subject of toxicological studies regarding (2,4-D). Some large tropical (e.g., Nyssodesmus python in Rica) are charismatic rainforest fauna that may startle human observers due to size and appearance. Chemical defenses may cause irritation if handled.
Similar Taxa
- Other Polydesmida familiesPolydesmidae distinguished by specific paranota structure and collum ; other in same order lack the combination of simple but well-developed dentate paranota with small transverse oval collum
- Centipedes (Chilopoda)Millipedes have two pairs of legs per body segment versus one pair in centipedes; Polydesmidae additionally distinguished by flattened plates and defensive curling versus predatory habits and venomous forcipules
More Details
Chemical defense
Many possess defensive glands along body margins that secrete noxious compounds including hydrogen cyanide, benzaldehyde, phenol, benzoic acid, benzoyl cyanide, and mandelonitrile when provoked
Cave-dwelling species
Epanerchodus includes multiple troglobitic (cave-dwelling) in southern China, indicating to subterranean within the
Species diversity
includes notable Polydesmus, Brachydesmus, Epanerchodus, Orthomorpha, and Schizoturanius, with ongoing taxonomic work describing new
Sources and further reading
- BugGuide
- Wikipedia
- GBIF taxonomy match
- iNaturalist taxon
- NCBI Taxonomy
- Destination Central Cordillera, Costa Rica: A visit with giant rainforest recyclers, Polydesmid millipedes — Bug of the Week
- The ecology of Polydesmus inconstans (Diplopoda: Polydesmidae) in Michigan woodlots
- The population ecology of Orthomorpha coarctata (Diplopoda : Polydesmidae)
- The reproductive biology of Polydesmus inconstans (Diplopoda: Polydesmidae) at constant temperatures
- The millipede family Polydesmidae in the Caucasus (Diplopoda: Polydesmida)
- Toxicity of 2,4-D to Millipeds (Polydesmidae: Diplopoda): Food Contamination and Residue Distribution as Factors
- Review of the genus Schizoturanius Verhoeff, 1931, with the description of a new species from the Altais, Asian Russia (Diplopoda: Polydesmida: Polydesmidae)
- The millipede genus Epanerchodus Attems, 1901 in continental China, with descriptions of seven new cavernicolous species (Diplopoda, Polydesmida, Polydesmidae)