Orthomorpha

With approximately 83 species, this large genus of mainly Asian distribution contains a variety of relatively small, colorful polydesmids that nonetheless poses problems for enthusiasts and continues to raise questions of taxonomic assignment even amongst diplopodologists, one example of which was noted elsewhere on this site with regards to the proper classification of Asiomorpha/Orthomorpha coarctata (1). These questions are in part due to the overall similarity of gonopod structure and the gonopod tip, the plasticity of external characteristics, and the incredible morphological variation amongst the various species, all characteristics which are usually used to differentiate different taxon (2). For enthusiasts without a microscope, this makes keying out what specimens are in one's collection difficult. To date a half-dozen or so species of Orthomorpha have been made available to enthusiasts, mostly in Europe: Orthomorpha weberi, Orthomorpha sp. "Ao Nang", Orthmorpha sp. "Khanom", Orthomorpha sp. "North Perak", Orthomorpha sp. "2" and sp. "3". Orthomorpha cf. arboricola has been made available to Russian enthusiasts. Captive breeding with "Ao Nang" (3), "North Perak" (4), and cf. arboricola has been reported. The numbering system for this genus to date has not yet been clearly delineated. Other species labeled under this genus, such as O. sp. "Red Spikes", "Bang Sung", O. sp. "1", and O. subkarschi have popped up on social media platforms from European and Asian vendors.

In captivity this genus seems to appreciate lots of rotting wood in its substrate similarly to Desmoxytes, and once adult specimens are settled it seems they can be quite prolific (5), and because of this they should also be monitored closely for signs of overcrowding; aside from these considerations, overall members of this genus seem to be unproblematic with standard millipede care. O. weberi (6) and likely other members of this genus secrete hydrocyanic acid and can poison themselves in enclosures with limited ventilation, so transport enclosures and the final enclosure should be properly ventilated.

Members of this genus are usually in-between 1-2"/2.5-5 cm, and come in a variety of colors and color patterns, with orange, red, pink, and yellow being common on a black, brown, or light tan/cream body. Specimens usually have posteriorly pointed paranota, and in some species this is the only part of the segment that is colored aside from the black or brown body, as is the case in A/O. coarctata and weberi.

Care notes for Orthomorpha cf. arboricola, by Philipp Byzov

This species is quite simple in terms of care, so much so that I have used them as cleaners in other terrariums. Initially I kept them in the same fashion as most of my other soil invertebrates; moist, humus-rich soil from an oak/grey alder forest with oak and beech leaf litter, white birch rot in a high degree of decomposition, with limestone as a source of calcium. Once every couple of weeks I put in zucchini for them to eat. I keep them between 20-25°C/68-77°F, and they grow quite slowly, going from protonymph to adulthood in usually eight months. They grow to about 7 cm/2.75". These specimens originally came from Bidoup National Park in Vietnam.

Adult specimen. Photos compliments of Philipp Byzov.

Orthomorpha sp. "North Perak" adult and babies. Photos compliments of Adriàn Purkart.

Orthomorpha sp. "Ao Nang" adult and babies. Photos compliments of Adriàn Purkart.

  1. Sierwald, P.; Spelda, J. (2021). MilliBase. Orthomorpha Bollman, 1893. Accessed at: https://www.millibase.org/aphia.php?p=taxdetails&id=892199 on 2021-12-24

  2. Likhitrakarn, N., Golovatch, S.I., & Panha, S. (2011). Revision of the Southeast Asian millipede genus Orthomorpha Bollman, 1893, with the proposal of a new genus (Diplopoda, Polydesmida, Paradoxosomatidae). ZooKeys, (131), 1–161. Accessed at: https://doi.org/10.3897/zookeys.131.1921 on 2021-12-24

  3. (2019). Skippy´s millipedes. Accessed at: https://arachnoboards.com/threads/skippy%C2%B4s-millipedes.323018/#post-2962166 on 2021-12-24

  4. (2019). Skippy´s millipedes. Accessed at: https://arachnoboards.com/threads/skippy%C2%B4s-millipedes.323018/page-2#post-2993991 on 2021-12-24

  5. (2016). Bandfüsser aus Laos - Diplopoda.de Forum. Accessed at: http://forum.diplopoda.de/forum/index.php?thread/6850-bandf%C3%BCsser-aus-laos/&postID=55309#post55309 on 2021-12-24

  6. Decker P., Pfeifle, R. (2021). Diplopoda.de. Accessed at: http://www.diplopoda.de/html/species/oweberi/_oweberi.php on 2021-12-24

  7. Purkart, A. (2019). Orthomorpha sp. Ao Nang. Orthomorpha Genus Page Header. Photograph. Permission granted solely to TMED.