Pyrgodesmidae

Distinguished from other polydesmid families by the combination of: small body size (<20 mm); fan-shaped collum completely or nearly completely covering the head from above with radiating dorsal ornamentation; tergites with downward-sloping lateral margins bearing rows of lobes or tubercles; ozopores on short columns with atypical segmental distribution; and absence of volvation. Some genera exhibit reduced segment number (19 segments in adults of Poratia versus typical 20 in Polydesmida).

Small millipedes ranging from 3–16 mm in length, predominantly 6–10 mm. Body uniformly grayish or brownish. Collum large, fan-shaped, covering most or all of the head from above, with dorsal surface ornamented by distinct radiating lines or small anterior lobes. Tergites slope downward with conspicuous lobes or tubercles usually arranged in rows. Ozopores often open on short columns and deviate from typical polydesmidan segmental distribution. Paranota frequently bear small lobes on anterior or posterior margins. Incapable of volvation (rolling into a ball).

Primarily tropical and subtropical forests, occupying leaf litter, soil, and decaying wood. Some species inhabit periodically inundated floodplain forests, including riparian zones of major river systems. Others are strictly terrestrial in dry forest habitats. Several genera are obligate inhabitants of ant colonies (myrmecophiles), including Myrmecodesmus, Calymmodesmus, Cynedesmus, and Rettenmeyeria. Some species occur in caves.

Pantropical and subtropical distribution: tropical Africa, southern Europe, North Africa, central China, Taiwan, Japan, southern United States (Texas) through Central and South America to Brazil, West Indies, India, East Indies, New Caledonia, Hawaii, and Pacific islands. Recently confirmed from Australia (Queensland), representing first native records for that continent.

• Ants - myrmecophilyObligate myrmecophiles in genera Myrmecodesmus, Calymmodesmus, Cynedesmus, and Rettenmeyeria; some species found exclusively in army ant colonies
• Termites - associationMyrmecodesmus hastatus recorded from termite nests

Development includes six juvenile stages prior to adulthood. In Poratia salvator, total development averages 66 days with maturity at approximately 75 days. Some populations complete life cycle within one year. Parthenogenetic species produce 7–10 eggs per nest with emergence after approximately 10 days. Survival to adulthood low (18% observed in laboratory). Generation time varies by population: shorter in floodplain populations, longer in terrestrial populations.

Low vagility with limited dispersal capability. Some species exhibit high colonizing ability facilitated by parthenogenetic reproduction. Thelytokous females in parthenogenetic populations may have greater desiccation resistance and lower energy expenditure than sexual populations due to absence of mate-searching and copulation. One species (Cryptocorypha ornata) apparently dispersed widely across Indian and Pacific Ocean islands through anthropogenic or avian transport.

Leaf litter decomposers in forest ecosystems. Contribution to nutrient cycling in tropical and subtropical forests, including periodically inundated floodplain systems.

Some parthenogenetic species (notably Poratia species) introduced to European hothouses. Potential for accidental transport through human activity, as evidenced by widespread distribution of some species on oceanic islands. Museum collections have proven valuable for documenting overlooked diversity, as demonstrated by discovery of Australian fauna in archived specimens.

• Other Polydesmida familiesPyrgodesmidae distinguished by small size, fan-shaped collum with radiating ornamentation, atypical ozopore distribution on short columns, and absence of volvation
• Poratia species with 19 segmentsAdults with 19 segments (versus typical 20 in Polydesmida) may be confused with other short-bodied polydesmids; identification requires examination of gonopod structure

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Uncategorized | Blog - Part 46
• Millipede family added to Australian fauna | Blog
• Life cycle of Poratia salvator (Diplopoda: Polydesmida: Pyrgodesmidae)
• Fertility tables of two populations of the parthenogenetic species Poratia salvator (Diplopoda, Polydesmida, Pyrgodesmidae)
• A new species of the millipede genus Cryptocorypha Attems, 1907, from northern Thailand (Polydesmida, Pyrgodesmidae)
• A new name for Myrmecodesmus potosinus (Shear) 1973, a homonym of Myrmecodesmus potosinus (Chamberlin) 1943 (Diplopoda, Polydesmida, Pyrgodesmidae)
• Filling a gap in the distribution of Taulidesmella tabatinga (Polydesmida, Pyrgodesmidae): a new record from the upper Amazon River, Brazil
• Morphological adaptations of the semiaquatic millipedeAporodesminus wallaceiSilvestri 1904 with notes on the taxonomy, distribution, habitats and ecology of this and a related species (Pyrgodesmidae Polydesmida Diplopoda)
• Detailed iconography of the widespread Neotropical millipede, Myrmecodesmus hastatus (Schubart, 1945), and the first record of the species from the Caribbean area (Diplopoda, Polydesmida, Pyrgodesmidae)