Narceus
Narceus is a relatively small genus of North American millipedes, containing four species: Narceus americanus, Narceus annularis, Narceus gordanus, and Narceus woodruffi, all of which are currently in the hands of breeders. Two other species that are listed as "Accepted" on Millibase, N. tinctorius and N. oklahomae, are excluded due to a lack of further information and for the fact that they are likely synonymous with the americanus/annularis complex. Each species is very variable across their respective ranges. Rowland Shelley, Chris McAllister, and Michael Medrano, writing in the Western North American Naturalist, note that Narceus "...occupies parts or all of 2 Canadian provinces, Québec and Ontario; every U.S. state east of the Mississippi River; and 9 states to the west including Minnesota, Iowa, Missouri, Arkansas, Louisiana, Nebraska, Kansas, Oklahoma, and Texas. Records are detailed for the 'western' states and New England and include the first from Minnesota, Connecticut, Delaware, and Maine; occurrence is projected for southeastern Minnesota and the Delmarva Peninsula. The genus presently comprises 2 valid species that are endemic to Florida - N. gordanus (Chamberlin, 1943) and N. woodruffi Causey, 1959 - and 2 of uncertain status that occur throughout the generic range and are referenced as the "N. americanus/annularis complex"; geographic evidence suggests greater diversity, particularly in the south, and a 2nd generic revision is in order to update the existing one by Keeton (1)."
All members of this genus except woodruffi (which prefers a straight flake soil substrate) do well with standard millipede care; in the wild the americanus/annularis complex from the East Coast is often reported as inhabiting tree holes filled with rotting wood and leaves, though they are also found under logs and crawling about leaf litter. The northern members of the genus, americanus and annularis, are generally more cold tolerant than tropical millipede species. All four species breed well in captivity; gordanus is reported as being a seasonal breeder.
N. americanus is the largest species in the genus, reaching to about 5"/12.7 cm, though annularis is similar in size. Both species tend to have gray bodies with varying shades of red, orange, dull tangerine, burgundy red, brown, etc. banding. Likewise leg coloration varies incredibly, from a cherry-blossom pink color to a cherry-fruit red. An albino stock of N. americanus was isolated by Orin McMonigle and has been established in the hobby. N. gordanus is a very thick species, and is shorter on average. Coloration ranges from a straight smoky grey to a bright gold coloration with subdued banding; some locales have red/orange hues. N. woodruffi is the black sheep of the genus, reaching to only about 2"/5 cm, with brownish coloration.
Wild observation of Narceus americanus/annularis, by Connor Smotzer
Several individuals were found outside of Hopewell, New Jersey in the Sourland Mountains, in the first week of September. All specimens found and photographed were mid day from 11:00AM-2:00PM, at approximately 70F/21.1C and on a day of high soil moisture following large amounts of rain due to Hurricane Ida two days prior.
The woods in which they were found are a hardwood forest, with the soil heavily composed of a rich, deep humus layer and igneous, trap, and basalt rock and boulder formations. All individuals were found in fallen and slightly decomposing Acer saccharum (sugar maple), Quercus alba (white oak), and Fagus grandiflora (American beech). The woods also contain numerous Lirodendron tulipifera (tulip tree), and perhaps I did not search enough, but as no individuals were found under any fallen tulip trees I examined, it seems it may not be be a staple food source at this particular locale for Narceus.
All individual Narceus were found above soil level by a few feet directly under loose bark of fallen trees elevated above the ground. The trees were not heavily decomposed, as in wet pith type material, instead still being firm. No Narceus were found in heavily decomposing wood. None were found on wood at soil level, or on soil. In every spot where Narceus was found, usually only one per spot, close proximity cohabitation was observed with Oniscus asellus. Individuals ranged from 1.5" to 3.5"/3.8 to 8.9 cm in length with slight variations in color tones.
Photos compliments of Connor Smotzer.
Wild Observation of Narceus americanus/annularis from Texas, by Alexander Martinez
On the night of September 4th, 2021, I found a number of Narceus sp. "Rocksprings" (from Texas); four adults, about 3"/7.6 cm in body length were found crawling around the cabin I was staying in around 10:00-11:00 PM. Throughout the stay from September 4th through to the 6th, I encountered many more adults, all wandering on the surface, and I don’t remember finding any under rocks. The entire area was quite dry with low humidity, with temperatures ranging from the low 70s°F/22.2°C at night to 95°F/35°C during the day. The habitat the specimens were found in is set on a steep hill that is very rocky, with a variety of small trees, shrubs, cacti, and grasses growing on the slopes.
I revisited the area again from October 29th to the 31st in 2021, during which I saw two adults and many babies, all of which were found under stones that were in the shade of trees from around 9:30 to 11:00 AM, with the most specimens found under a single rock being four babies loosely clustered around each other. When first exposed the babies would not react, before eventually beginning to move away, while the two adults immediately curled up. No specimens were found wandering at night, with the temperatures dropping into the low 60s°F/16°C at night, and peaking at 80°F/26.6°C during day. It had rained two days prior, and while the humidity was elevated the ground was still quite dry.
Photos of habitat and specimens compliments of Alexander Martinez.
Narceus americanus/annularis complex, North Carolina locale, photo compliments of Grant Haigney.
Narceus woodruffi, photos compliments of Alan Jeon.
Narceus americanus "Albino", photos compliments of Kevin Nasser.
Narceus americanus "Wekiwa", photo compliments of Kevin Nasser.
Narceus gordanus adult with immatures, photo compliments of Alan Jeon.
Sierwald, P, Spelda, J. (2021). MilliBase. Narceus Rafinesque, 1820. Accessed at: http://www.millibase.org/aphia.php?p=taxdetails&id=892084 on 2021-11-13
Shelley, Rowland M.; McAllister, Chris T.; and Medrano, Michael F. (2006) "Distribution of the milliped genus Narceus Rafinesque, 1820 (Spirobolida: Spirobolidae): occurrences in New England and west of the Mississippi River; a summary of peripheral localities; and first records from Connecticut, Delaware, Maine, and Minnesota," Western North American Naturalist: Vol. 66 : No. 3 , Article 11.
Smotzer, C. (2021). Narceus americanus/annularis. Photographs 1-6.
Haigney, G. (N.A.). Narceus americanus/annularis complex, North Carolina locale. Photograph.
Jeon, A. (N.A.). Narceus woodruffi. Photograph. Photographs 1&2.
Jeon, A. (N.A.). Chicobolus spinigerus “Archbold” & “Miami”. Photographs. 1 & 2.
Nasser, K. Nucleus americanus “Albino”. Photograph. Photographs 1-3.
Nasser, K. (N.A). Narceus americanus “Wekiwa”. Photograph.
Jeon, A. (N.A.). Narceus gordanus adult with immatures. Photograph.