Acladocricus

There are twenty species of Alcadocricus sp. recognized, though all specimens in the trade up to this point remain unidentified to the species level, due to the similar morphology of the species in the genus. In this regard they are often labeled as Acladocricus sp. "Philippine Blue", though it is believed all the current stock to be found in the hobby to have originated from Negros Island. If this is true the options are narrowed down drastically, as only four described species and one unknown species of Acladocricus are known from the Philippines: A. cupulifer, major, philippinus, porus, and an A. sp. nov. mentioned by Yu-hsi Moltze Wang in his dissertation The Myriopoda of the Philippine Islands, and only two, porus and the A. sp. nov., are to date known from Negros Island.

This species does well with standard millipede care, though it requires large amounts of quality rotting wood in order for juveniles to develop properly. Captive populations appear to grow smaller over time, maturing at about five to six inches (12.7-15.2 cm), while recently imported stocks commonly reach to seven inches (17.8 cm) and beyond; there is one report of a roughly 11 inch (22.9 cm) long wild caught female from Negros Island, though doubtless this is not the norm.

Coloration ranges from the azure blue commonly seen to varying shades of grey, green, and brown, depending on the specimen's development. For the first few instars they are white, before starting to attain a pale grey to grey color; the blue only fully develops near or at maturity. Behaviorally this species is generally fossorial, and will often spend long stretches of time under the substrate.

Photos compliments Stephanie Risberg (2) and Kevin Nasser (3). First two are of Orin McMonigle's stock, third is of Shawn Kramer's stock.

Breeding Report of A. sp. "Philippine Blues," by spider_nerd

Four wild caught adults (3 males, 1 female) approximately 16 to 17 cm (6.3 to 6.9 inches) were placed in a large Sterilite tub with 33 cm (13 inches) of substrate, which was composed of rotten hardwood and shredded peat. Temperatures ranged from 17.5°C to 32°C (63.5°F to 89.6°F). Adults died after about nine months, presumably due to old age. Three of the four molted once with no noticeable growth. Protonymphs were discovered in June 2020 and as of October the estimated 20-40 young were about 3.8 cm (1.49 inches).

A. sp. "Philippine Blue", purportedly from Negros Island. Photo compliments of spider_nerd (4).

Findings on the possible identity of hobby Acladocricus from Negros Island, by spider_nerd and Arthroverts

A dissection of the gonopods of a male specimen believed to have originated from Negros Island (of the same stock as the above breeding report) was carried out by spider_nerd, and the findings have further limited the list of available options for hobby Acladocricus (assuming the specimens in captivity are not undescribed) to either A. porus or the A. sp. nov. mentioned by Wang in his dissertation The Myriopoda of the Philippine Islands. A. porus appears to only be found in the north of Negros Island, which is corroborated by iNaturalist observations of Acladocricus on the island (5), while the A. sp. nov. is found in the south, which is again corroborated by iNaturalist observations (6) (7).

The majority of specimens in captivity superficially mirror Wang's description of A. porus; “The coloration is not very uniform being dusky in general with the prozonites lighter but not so distinctly differentiated as the generotype.” The banding of porus is not seen on the A. sp. nov. Wang described; “The coloration is more regular than that of the A. major, no slightly lighter area on dorsum and shines metallically. [sic]” This seems to suggest that the specimens kept in captivity are porus, but a definitive answer is simply not possible at present, as Wang's drawings of the gonopods of porus as compared to A. sp. nov. are too similar to draw anything conclusive from, and further sampling from Negros Island is needed.

Notes on Acladocricus sp. "Java"

Currently there is a species being offered from a number of vendors called Acladocricus sp. "Java", "Yellow-Legged Giant", and "Javan Yellow-Legged Giant" (it is also called by the same names under the genus Thyropygus, adding to the confusion surrounding this species). In Germany this species has been called Thyropygus sp. "4" (8).

It is a very large species that presumably can reach up to 30 cm/12", with some reports suggesting that it can even grow to over 35 cm/13.7", though exact measurements are lacking. As the name suggests most specimens have bright yellow legs. The body is a glossy, smooth black, though on some specimens some very dark brown banding might be discerned at the intersection of segments under very bright light (9); other specimens have pronounced reddish striping. The antenna are a reddish-brown. While smaller specimens appear to be rather thin, large specimens are incredibly massive and rival many similar sized species in sheer bulk.

This species appears to be fairly day-active, though it also tunnels to a large degree, and consumes leaf litter in quantity according to one report (10). Breeding has not been witnessed in specimens exported to Europe. A very similar species with reddish-pink legs from Sulawesi has also been made available. One enthusiast reports (11) that males of this species mate rather violently with females and sometimes even each other. A video of this behavior is attached below (12).

The taxonomic status of this species is still very much unknown. There are no known Acladocricus from Java, meaning this species is either an undescribed species of the genus, a new record of the genus, or something else all together (13). Whether it is a rhinocricid at all remains to be seen.

Photo compliments of MontePython (14). Largest specimen is a female Archispirostreptus gigas, second largest specimen is a male "Javan Yellow-Legged Giant", smallest specimen is a male Spirostreptus servatius.

A video of violent mating behavior in Acladocricus sp. "Java" (12).

Millibase- Sierwald, P.; Spelda, J. (2021). MilliBase. Acladocricus Brölemann, 1913. Accessed at: http://www.millibase.org/aphia.php?p=taxdetails&id=890878 on 2021-11-13
Risberg, S. (N.A.). Acladocricus. Photograph.
Nasser, K. (N.A.). Acladocricus. Photograph.
Spider_nerd (N.A.). Breeding Report of Acladocricus sp. “Phillipine Blues”. Via Email.
iNaturalist. (2021). Genus Acladocricus (Needs ID). Kennethh252. https://www.inaturalist.org/observations/61864632
iNaturalist. (2018). Round-backed millipedes (Superorder Juliformia). aubreymoore. https://www.inaturalist.org/observations/19347061
iNaturalist. (2019). Round-backed millipedes (Superorder Juliformia). nina194. https://www.inaturalist.org/observations/31108253
Thyropygus sp. "4".- Sigling, S. (N.A.). Thyropygus Sp. 4. http://www.millipeden.org/2012/mp_pages/mp1059_1.html
(2020). Acladocricus sp. vs. Thyropygus sp. (ID conundrum). Accessed at: https://arachnoboards.com/threads/acladocricus-sp-vs-thyropygus-sp-id-conundrum.334973/ on 2021-1-5
MontePython. (2020). Acladocricus sp. vs. Thyropygus sp. (ID conundrum). https://arachnoboards.com/threads/acladocricus-sp-vs-thyropygus-sp-id-conundrum.334973/
Istaaz. (2016). Millipedes entwine-looks like a strangler snake. Jun, 1 Post #1. Accessed at: http://forum.diplopoda.de/forum/index.php?thread/6754-tausendf%C3%BC%C3%9Fer-umschlingen-sich-sieht-aus-wie-bei-einer-w%C3%BCrgeschlange/&postI on 2021-1-5
Preller, J. (2016). Umschlingen. Video. https://www.youtube.com/watch?v=uc9x6J_hkWA
Marek, P., Bond, J., & Sierwald, P. Rhinocricidae Sytematics II: A species catalog of the Rhinocricidae (Diplopoda: Spirobolida) with synonymies. Zootaxa, 308(1), 1-108. https://www.researchgate.net/publication/237424614_Rhinocricidae_Systematics_II_A_species_catalog_of_the_Rhinocricidae_Diplopoda_Spirobolida_with_synonymies
MontePython (N.A.). Archispirostreptus gigas, “Javan Yellow-Legged Giant”, & Spirostreptus serviatus. Photograph.

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