Trigoniulus corallinus

(Eydoux & Souleyet, 1842)

Rusty Millipede, Common Asian Millipede

Trigoniulus corallinus is a large native to the Indo-Malayan region that has become established as an introduced across multiple continents. reach 50–75 mm in length and are characterized by a uniform reddish-brown coloration. The species inhabits moist terrestrial environments, particularly areas rich in decaying organic matter. It was the first millipede to have its sequenced (2015), and subsequent research has identified an XX/X0 system with males possessing modified seventh-leg pairs () used for mating.

Trigoniulus corallinus by (c) Lawrence Hylton, some rights reserved (CC BY), uploaded by Lawrence Hylton. Used under a CC-BY license.

Pronunciation

How to pronounce Trigoniulus corallinus: /trɪˈɡoʊniˌjuːləs kɔˈrælinəs/

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Identification

Large size (50–75 mm) and uniform reddish-brown coloration distinguish it from smaller or differently colored millipedes in overlapping ranges. Males can be identified by modified seventh-leg pairs (). Aggregated distribution pattern during peak abundance may aid in detection.

Images

Appearance

size ranges 50–75 mm (2–3 inches). Uniform reddish-brown coloration. Males exhibit distinct : modified seventh-leg pairs form used for mating.

Habitat

Moist terrestrial environments, especially areas rich in organic matter. Documented from rotten wood, compost during monsoon season, decaying coconut trees, and open land with high organic content. Distribution within is patchy, driven by food availability, soil moisture, and sexual attraction factors.

Distribution

Native to Indo-Malayan region: India, Bangladesh, Sri Lanka, China, Taiwan, Philippines, Myanmar, Thailand, Vietnam, Malaysia, Brunei, Singapore, Nepal, Indonesia. Introduced and established in Fiji, Tanzania, Zambia, Caribbean, and Florida (USA); well-distributed in South and Central Florida with limited sightings in Northeast and Panhandle.

Seasonality

and significantly correlated with minimum temperature and rainfall. and late stadia abundant in June, October, and November; August include all developmental stages.

Host Associations

Pseudomonas schmalbachii - bacterial isolated from digestive tract; type strain Milli4T described from this

Life Cycle

Developmental stages show length progression factor 1.11–1.98 (mean 1.43) and width progression factor 1.10–1.56 (mean 1.31). Female weight progression exceeds male, attributed to -forming tissue accumulation. Monthly age structure: and late stadia abundant June, October, November; August includes all stadia.

Behavior

Aggregated distribution during peak abundance periods. Patchy spatial distribution influenced by food resources, soil moisture, and sexual attraction.

Ecological Role

Vital decomposer of litter; recycles nutrients in soil . ranges 2.13–56.31 individuals/m²; 1026.38–8494.38 per m² in studied .

Human Relevance

Introduced in multiple regions including Florida, Caribbean, and parts of Africa. Subject of first sequencing (2015). Source of novel bacterial species (Pseudomonas schmalbachii) from gut microbiome research.

More Details

Genomic significance

First to have sequenced (2015). Male genome: 546 Mb; female genome: 630 Mb. XX/X0 system identified through male and female genome assemblies and resequencing of 20 individuals. X characterized by low gene , high repeat content, and limited synteny conservation with X chromosomes.

Population ecology

Year-long study showed and significantly correlated with minimum temperature and rainfall. Population exhibits aggregated distribution during peak abundance due to patchy resource distribution and sexual attraction.