2023 Collecting Summary

Local mixed forest habitat, showing the grandeur of winter collecting. Photo taken 16 January 2023.

Continuing my trend from 2021 and 2022, it’s time for the summary of my myriapod collecting during 2023! I made a concerted effort last year to collect less so that I could focus on other things (mainly writing, curation of my specimens, and job hunting), but I still found a number of interesting and rare species. An added bonus from last year is that a number of friends and colleagues sent me specimens from far-flung areas, which added some exceptional species to my collection. I want to give a particular thank you to Lance Andrew, Joe Girgente, Adam Haberski, Curt Harden, Brendan O'Loughlin, and Carol Tingley for sending me their specimens.

Thanks to the specimens sent to me by colleagues, the collecting map spans the continent! The Alaska locality especially sticks out, and represents some beautiful Parajulidae.

Map of 2023 collecting localities

 I totaled 37 collecting events in 2023, spanning only two states: Virginia and Ohio. All the dots on the map from outside those states are specimens sent to me by other people, and those specimens really augmented my collection last year! The numbers I’m using for the rest of this post include the specimens sent by colleagues.

Total myriapod specimens collected in 2023

All in all, my colleagues and I collected 1,450 myriapods in 2023, as shown in the above graph (blue bars, left axis). The total number of collection events are represented by the orange line, with numbers reflected on the right axis. There were a total of 81 collection events last year: I did 37 of them, while my colleagues conducted 44. Again, the value of others collecting myriapods for me is immense!

These collections included 109 species from 36 families, beating 2022’s count of 88 species from 30 families. Those 109 species include 71 genera, including a number of unique genera I didn’t have in my collection before. Last year I wrote about wanting to top 100 species in a year, and I achieved that goal!

Since this is my third year of tracking this data, I can include my previous years of data to see how my collecting habits have differed.

Total specimens collected monthly, 2021-2023

The above graph shows the total number of specimens collected during each month from 2021-2023. There’s quite a bit of variation there, mostly reflecting collecting effort. The totals from 2021 are quite low until September 2021, since that’s when I started using my homemade Berlese funnels. The main takeaway here is that collection effort is typically the most important determiner of how many specimens I collect each month, with local weather playing a part as well. Totals from November through February tend to be lower than Spring through Fall, but there are, of course, exceptions. Additionally, if you want to get the full picture of your local myriapod diversity, you’ll miss unique cold weather-active species if you don’t collect between November and February.

I’ve collected throughout the year enough now to recognize a few distinct myriapod faunal groups. There are species like Nadabius pullus (Lithobiomorpha: Lithobiidae) that you can find easily throughout the year. Other groups like the Apheloriini (Polydesmida: Xystodesmidae) are most active during the spring and fall. And then there are other species, like the genus Garibius (Lithobiomorpha: Lithobiidae) and many Chordeumatida, which are active during late fall through early spring. Figuring out which species fit these various seasonal patterns (and which ones don’t!) is one of the most fulfilling parts of collecting myriapods for me personally. The cold weather-active species in particular are some of the most exciting to find, as these are typically rare in collections, despite their ubiquity during their active season. Besides, you pretty much have the entire woods to yourself while searching for them. It’s quite pleasant to grub around in the dirt in brisk weather.

Another fun thing to check the yearly data for is the number of unique species per month, shown in the graph below:

Number of species collected monthly, 2021-2023

These monthly totals are somewhat less variable than the total specimens collected each month, but collecting effort still has a strong influence (see November 2023!). These totals can be highly influenced by colleagues sending me specimens, particularly if they’re based outside of Virginia. The standout from this chart is April 2023, with the most species I’ve ever collected in a month, at 51! That was also the month with the highest total specimens, at 297 (see previous graph).

Diving into the 2023 species-specific data, there are similar trends to my 2022 collecting. Once again, the centipede Nadabius pullus (Lithobiomorpha: Lithobiidae) was my most-collected species, represented by 154 specimens, less than last year’s count of 195 specimens. The full top ten list is:

Nadabius pullus (154), Nampabius sp 1 (90), Arctogeophilus umbraticus (70), Oxidus gracilis (70), Hanseniella sp (63), Strigamia branneri (60), Typhlobius sp (52), Ptyoiulus impressus (49), Chaetaspis sp (40), Paitobius zinus (36)

The four names in bold are species that weren’t on last year’s list. Collectively, these 10 species account for 51% of all myriapods collected in 2023. At the other end of the spectrum, 32 species are represented by 1 or 2 specimens, making up only 3% of the total specimens collected, but 29% of the total species collected. Sometimes those singletons pack a big punch diversity-wise.

I was able to find a number of lifer species in 2023, including some I had been after for years! One of my favorites was the centipede Agathothus gracilis (Geophilidae: Linotaeniinae), which has only been reported a few times from Tennessee and southwest Virginia. It’s one of only two genera of Linotaeniinae in eastern North America, and is far rarer than the common Strigamia. I wasn’t sure I’d be able to recognize a specimen of A. gracilis, but after seeing the forcipules, it’s unmistakeable—they’re flattened and sharp, and lack the tarsungular tooth of Strigamia, making A. gracilis immediately recognizable.

Agathothus gracilis, head and anterior segments, ventral view.

By far my most surprising find of 2023 was a liliputian geophilomorph, the enigmatic Nannarrup hoffmani. Funnily enough, 2023 marks the species’ 20th birthday, having originally been described from Central Park in New York City in 2003. I found half a dozen specimens in southwest Virginia, while looking for a different species entirely! The species itself is native to an unknown part of east Asia, and only recently has the genus been found in its native range (see Tsukamoto et al. 2022). This is a new state record for the species (and the family) and makes it likely that N. hoffmani will turn up in additional states, if searched for.

Nannarrup hoffmani: live specimen in soil matrix (left) and ventral view of forcipules (right).

Another geophilomorph I was happy to find was Strigamia hoffmani, a species only described in 2009 in honor of Richard Hoffman’s 80th birthday. It’s a small species that can be difficult to separate from Virginia’s other species of Strigamia, and is only known from Tazewell and Roanoke counties. In 2023, I found it in two additional counties: Grayson and Giles. The key to finding this one may be searching areas over 1,000 m in elevation, suggesting a more boreal-adapted species. It still hasn’t been found outside of Virginia, so get searching, those of you in surrounding states!

Last year brought me my first specimen of Lamyctes pius (Lithobiomorpha: Henicopidae), likely a synonym of L. emarginatus (see Shear 2018). Chamberlin described a number of species within the genus Lamyctes, but the evidence points to them being an introduced species in North America. Native henicopids are rare here, as the family is mainly confined to the southern hemisphere.

Lamyctes pius (Lithobiomorpha: Henicopidae) head, dorsal view (left) and ventral view (right)

Moving on to the millipedes, there were a number of surprises this year. Down in Wise County, I found my first sphaeriodesmid in Virginia: Desmonus earlei!

Desmonus earlei, lateral view

This is a slight range extension and only the second record for Virginia that I know of; previously it had been recorded from Lee County. There’s another Desmonus species that ranges from Missouri south to Texas and adjacent Mexico, Desmonus pudicus. Both species are quite small, only about 5 mm across when curled into the loose spiral pictured above, and maybe a centimeter fully extended. Despite their small size, they’re immediately recognizable by the large dorsal tubercles on their rings, and by their coating of dirt. While Desmonus is the only representative that occurs in the US, the family Sphaeriodesmidae is more diverse in Mexico and down through South America, and it’s always a treat to see one of these species.

Desmonus earlei gonopods, posterior view (left) and lateral view (right)

There’s one more polydesmidan millipede I want to highlight, and it was by far the biggest millipede find of my year. I was meeting a friend at a park in Wythe County, and while I was waiting, I scratched around in the leaf litter near a stream to see what I could find. Within five minutes, I found some small cherry millipedes (Xystodesmidae) and did a double take:

Rhysodesmus restans, dorsal view of live specimen

“No way,” I whispered to myself. This was Rhysodesmus restans, something of an artifact in Appalachia. Almost all species of Rhysodesmus are further south, in Texas, Mexico, and Central America. But there are a few still around, left behind in the Appalachian Mountains. I’d been searching for this species for years at this point, and always much further away, down in Washington County (the type locality). Even better: they were abundant here! I collected a number of specimens and left more behind, still in disbelief at my luck.

The final species I’ll highlight is a hidden gem that I’d actually collected multiple times in the past few years, but which I had misidentified. This was pointed out to me by my colleague Pierre-Marc Brousseau, to whom I’m grateful! A small millipede in the order Julida, the species Okeanobates americanus is one I had read about, but that was the limit of my experience with it.

Okeanobates americanus, lateral view

It turns out that I had unknowingly collected this species almost yearly since 2020! I had it misidentified as an unknown species of Blaniulidae, but Pierre-Marc noticed the rectangular eye patch in one of my iNaturalist photos and corrected me. The species ranges from North Carolina up through Quebec, Canada, but is uncommon. It seems to favor life within logs, as I’ve never found it in leaf litter. I included more information about the species and the Okeanobatidae in a blog post back in November, so check that out to learn more. It’s not often that I get to add a new family to my collection, what a thrill!

That about wraps up my 2023 review. I found some superb species last year, and much of that was thanks to friends and colleagues, to whom I’m indebted for sending me specimens.

Possibly the strangest thing I did last year was that I accidentally ended up writing a key to all eastern geophilomorph centipedes. I meant to focus on Lithobiomorpha in 2023, but got hooked on those weird little soil centipedes. If you’re interested in using the key or sending me geophilomorphs from your region, please get in touch. It will be a little while before I publish it, but I’m aiming to write up centipede resources in the next few years to focus attention on the North American fauna, especially in the east.

This post has gone on long enough, so I’ll end it here with a photo comparison of the new litter sifter I bought in 2023. It replaces my previous sifter, which I’d been using for almost a decade. Can you tell which is which?

Further reading:

Chamberlin RV (1912) The Geophiloidea of the southeastern states. Bulletin of the Museum of Comparative Zoology at Harvard College 54: 405–436. https://www.biodiversitylibrary.org/page/2815547

Enghoff H (1979) The millipede genus Okeanobates (Diplopoda, Julida: Nemasomatidae). Steenstrupia 5: 161–178.

Hoffman RL (1998) An Appalachian species of Rhysodesmus (Polydesmida: Xystodesmidae: Rhysodesmini). Myriapodologica 5: 77–83. https://www.biodiversitylibrary.org/page/52243216

Pereira LA (2009) A new dwarf species of the genus Strigamia Gray, 1843 from the southern Appalachian Mountains of western Virginia (Chilopoda: Geophilomorpha: Linotaeniidae). Virginia Museum of Natural History Special Publication 16: 209–222.

Shear WA (2018) The centipede family Anopsobiidae new to North America, with the description of a new genus and species and notes on the Henicopidae of North America and the Anopsobiidae of the Northern Hemisphere (Chilopoda, Lithobiomorpha). Zootaxa 4422: 259–283. https://doi.org/10.11646/zootaxa.4422.2.6

Shelley RM (2000) Revision of the milliped subfamily Desmoninae (Polydesmida: Spheriodesmidae). Myriapodologica 6: 27–54. https://www.vmnh.net/content/vmnh/uploads/PDFs/research_and_collections/myriapodologica/myriapodologica_v6_5.pdf

Tsukamoto S, Shimano S, Eguchi K (2022) Two new species of the dwarf centipede genus Nannarrup Foddai, Bonato, Pereira & Minelli, 2003 (Chilopoda, Geophilomorpha, Mecistocephalidae) from Japan. ZooKeys 1115: 117–150. https://doi.org/10.3897/zookeys.1115.83946

An unexpected millipede and a key to the families of the order Julida in North America.

Snake millipedes (order Julida) aren’t the flashiest millipedes. They sometimes make their way into homes and can derail trains, habits that people don’t generally view gracefully. We all have our flaws.

Sooner or later, you’re likely to run into one. The order is mainly Holarctic, but it can now be expected most anywhere thanks to transport by humans. The Julidae and Blaniulidae are shining examples of success through human assistance, and you’re probably not far from a representative of one of those species right now.

Ophyiulus pilosus (Julidae), a species native to Europe but now found widely across continents, including North America.

That’s not to say that all Julidans are drab and mucking around where they shouldn’t be, however. We have a number of native families here in North America, including my personal favorite, the Parajulidae. Parajulid males are instantly recognizable by their enlarged, almost tusk-like first leg pair.

A male Parajulid in the tribe Uroblaniulini from North Carolina, showing off its enlarged first leg pair.

While the Parajulids are my favorite, hands-down the most beautiful Julida in North America live over in potato country: Idaho. Represented by only one described species, the Chelojulidae are breathtakingly gorgeous. They’re instantly recognizable by their dorsal and lateral crests, a unique character within the Julida and more reminiscent of the Cambalidea or Callipodida.

Chelojulus sculpturatus (Chelojulidae) mating. Photo by Casey Richart, CC-BY.

Here in Virginia, I’m content with my Parajulids (while I plan my Idaho collecting trip). Another family I tend to find is the Blaniulidae, which are mainly found underneath and within logs. These are pale white to light brown millipedes which are very thin (we’re talking less than a millimeter in width), and not particularly interesting. Most of our species are introduced, except for Virgoiulus minutus, and males are very rare. Many Blaniulids reproduce via parthenogenesis, in which unmated females can lay viable eggs—no male necessary. It’s hypothesized that this parthenogenetic condition is a result of these millipedes’ bark-dwelling lifestyle (Enghoff 1994), a connection that has been documented within a number of Julidan families.

Proteroiulus fuscus (Blaniulidae), an introduced species from Europe. Species in this family often have a single line of ocelli, or they’re absent entirely.

I don’t have a ton of Blaniulids in my collection, partly because I focus on leaf litter when I’m out collecting instead of checking logs. It’s not a family I seek out since most species I’ll find are introduced, but I grab them when I happen across them. I take a quick look under the scope and identify them (or leave them at the family level if I’m pressed for time) and move on—maybe I’ll upload a photo to iNaturalist. That’s what I did last spring with a couple specimens I identified as Proteroiulus fuscus, and thought nothing more of them.

The aforementioned millipedes; note the triangular patch of ocelli.

But then a few weeks ago, my colleague Pierre-Marc Brousseau noted that the eye pattern didn’t match for P. fuscus, and he was right! Within the Blaniulidae, species have either one row of ocelli or lack ocelli—none have a triangular patch of ocelli like these ones. That left me with two options: either the Okeanobatidae or the Nemasomatidae, both of which are considerably rarer than the Blaniulidae.

The Nemasomatidae are unique within the Julida in having secondarily free sternites which aren’t fused to the pleurotergites, as in the other families of the order. I did a quick dissection of one of my specimens, and its sternites were fused to the pleurotergites (though the plate itself had slight sutures delimiting the edges of the sternites, which is typical but can be confusing if you haven’t seen Nemasomatid-type sternites before)—a match for Okeanobatidae.

In North America, we only have one species of Okeanobatidae, Okeanobates americanus, and this was it!

Two juveniles, Okeanobates americanus. Note the scale at the top: the black marks are millimeters. These are diminutive millipedes, with adults reaching a centimeter in length.

This was my first time seeing this species (and genus! and family!), a thrill! Its range in North America is limited to the Central Appalachian Mountains (North Carolina, Tennessee, Kentucky, and Virginia) north to Ontario and Quebec. After checking these two specimens, I went through all my specimens identified as Blaniulidae to search for other misidentifications, and I found three additional specimens. Two were from Montgomery County, Virginia, and one was from Monroe County, West Virginia. These specimens represent the second Virginia record for the species and the first record of the species for West Virginia. I bet they’re more widespread, but easily confused for other species, in addition to being tightly locked to their subcortical habitat and unlikely to be found outside of it. Obviously, I need to be checking logs more often.

O. americanus is very likely parthenogenetic (see discussion in Enghoff 1979), and the male has yet to be found. Even within parthenogenetic species, males pop up from time to time, though it’s quite rare. In their study of Virgoiulus minutus (Blaniulidae), Enghoff & Shelley (1979) examined about 875 specimens and found 4 males, coming out to about 0.5% of their specimens. If that ratio holds true for O. americanus, then we’ll still be searching for a while until we find a male.

Other species in the Okeanobatidae are known from Japan, representing a trans-Beringian connection between the myriapod fauna of East Asia and North America. This biogeographical connection has been recognized in a few other millipede families, such as the Nemasomatidae, Parajulidae, Andrognathidae, and Xystodesmidae.

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While I was working on identifying these Okeanobates americanus, I realized that I would love to have a handy key to identify any Julida I collect in North America. Most of them I can pretty easily identify by sight, but uncommon families like the Blaniulidae and Nemasomatidae always send me searching through my computer for various references. To fix this, I wrote a key covering all families of Julida that occur in North America, native or introduced, presented below.

Many helpful characters were gleaned from the key in Enghoff (1991), which was written for use with adult males (and includes all Julidan families, rather than just ones occurring in North America). I’ve striven to make my key usable with adults of any sex, but I still include useful sexually dimorphic characters when available. I appreciate any feedback on the key, especially if you find errors.

Key to North American families of the millipede order Julida

last updated 27 Nov 2023

1a. Body rings with a pair of rounded crests dorsally and linear crests laterally……Chelojulidae.

• Only known from northern Idaho, one species: Chelojulus sculpturatus. An exceptionally beautiful millipede.

Fig. 3 from Enghoff 1982, showing crests in dorsal view of Chelojulus sculpturatus

1b. Body rings lacking crests, at most with impressed striations………………………………...2.

2a. Epiproct bifurcate into two spines………………………………………Telsonemasomatidae.

• 6-12 mm long, 1-3 ocelli on each side of the head. One species, from Benton Co., Oregon.

Fig. 5 from Enghoff 1979, showing bifurcate epiproct of Telsonemasoma microps, colors inverted for clarity.

2b. Epiproct not produced, or if produced, not bifurcate……………………………….………....3.

3a. Body rings with strongly impressed striations encircling entire ring……………………………4.

3b. Body rings with slightly impressed striations only present below the level of the ozopores………. ...………………………………………………………………………………………………….6.

4a. Gnathochilarium with promentum short, only separating lamellae linguales basally; male first leg pair hook-like; body length ca. 7-30 mm..........……………………………………….…….Julidae.

• An introduced family native to the Palearctic, common near human development. Often found in large numbers, occurs throughout North America.

4b. Gnathochilarium with promentum long, completely separating lamellae linguales; male first leg pair very short, with small tibial outgrowths directed sublaterad; body length ca. 16-165 mm………

………………………………………………………………..………..……Paeromopodoidea, 5.

5a. Large-bodied millipedes ca. 51-165 mm long, with broad longitudinal yellow stripes or dark to light transverse bands on body rings…………………...…………………………Paeromopodidae.

• Western North America: distributed in California, Oregon, Washington, Idaho, and Montana; two genera: Paeromopus and Californiulus. Includes the largest millipedes in the Nearctic region.

5b. Small-bodied millipedes ca. 16 mm long, with body rings dark mottled brown and lacking longitudinal stripes or transverse bands…………………...……...…………Aprosphylosomatidae.

• One species, Aprosphylosoma darcenae, only known from one locality in Josephine County, Oregon.

6a. Large-bodied millipedes ca. 19-58 mm long, diameter ca. 2 mm or more; strongly pigmented, light orange to dark purple; males with greatly enlarged first leg pair; ocelli present in a triangular field; mandibles with 6 or more pectinate lamellae………………………………..……Parajulidae.

• Speciose and common throughout North America.

6b. Small-bodied millipedes ca. 5-20 mm long, diameter less than 1 mm; depigmented to bronze brown in color; male first leg pair not greatly enlarged, but may be modified into hook-like structures or have reduced podomeres; ocelli absent or present in a linear row or triangular field; mandibles with 4 or 5 pectinate lamellae……………………………..……………………………7.

7a. Sternites free from pleurotergites, with anterolateral wing-like expansions; eyes present in a triangular field; male first legs reduced in size, but not hook-like……….…...…….Nemasomatidae.

• Two genera: Orinisobates and Thalasissobates. Orinisobates is associated with rotting logs in the Pacific Northwest and Central Appalachians, with disjunct records from Illinois, Florida, Utah, and Wyoming. Thalasissobates is associated with littoral habitats on the Atlantic Coast and has been reported from New Brunswick, Massachusetts, and Virginia.

Fig. 2 from Enghoff, 1985, showing the free sterna and the anterolateral wing-like expansions of Nemasoma varicorne.

7b. Sternites fused to pleurotergites, lacking anterolateral wing-like expansions; eyes absent or present in a linear series or triangular field; male first leg pair unmodified, slightly reduced in size, or modified into hook-like structures……………………..…………..………………Blaniuloidea, 8.

8a. Gnathochilarium with base of promentum straight or convex; ocelli absent or in a linear series; male mandibular cardo and stipes typically produced into a forceps-like structure.…….Blaniulidae.

• Most species introduced from Europe, now found across the continent; one species (Virgoiulus minutus) native to eastern North America.

8b. Gnathochilarium with base of promentum concave; ocelli absent or in a triangular field; male mandibular cardo and stipes unmodified………………………………………...……………......9.

Modified Fig. 5 from Enghoff 1979, showing gnathochilarium of Okeanobates americanus. p: promentum

9a. Ocelli in a triangular field; mottled brown in color; gnathochilarium with laminae linguales not extending past base of promentum; female vulvae within a deep vulval invagination………………... …………………………………………………………………………………….Okeanobatidae.

• One species, Okeanobates americanus, found from Ontario and Quebec south to North Carolina and Tennessee.

9b. Ocelli absent; pale, depigmented; gnathochilarium with laminae linguales extending past base of promentum and fitting into shallow concavities of the stipites; female vulvae within a short vulval invagination……………………………………………………………….…...…..Zosteractinidae.

• Small cave-adapted millipedes, two genera. Ameractis is known from caves in Tennessee, Alabama, North Carolina, and Virginia. Zosteractis is reported from caves along the Mississippi River in Missouri and Illinois.

Modified Fig. 18 from Hoffman 1963, showing gnathochilarium of Ameractis satis.

References:

Blower JG (1985) Millipedes. Synopses of the British Fauna (New Series) 35. E. J. Brill, London, 242 pp.

Enghoff H, Shelley RM (1979) A revision of the millipede genus Nopoiulus (Diplopoda, Julida: Blaniulidae). Entomologica Scandinavica 10: 65–72.

Enghoff H (1979) A new genus and species of the millipede family Nemasomatidae (Diplopoda, Julida). Steenstrupia 5: 149–159.

Enghoff H (1979) The millipede genus Okeanobates (Diplopoda, Julida: Nemasomatidae). Steenstrupia 5: 161–178.

Enghoff H (1982) An extraordinary new genus of the millipede family Nemasomatidae (Diplopoda: Julida). Myriapodologica 1: 69–80. https://www.vmnh.net/content/vmnh/uploads/PDFs/research_and_collections/myriapodologica/myriapodologica_v1_n11.pdf

Enghoff H (1985) The milliped family Nemasomatidae. With description of a new genus, and a revision of Orinisobates (Diplopoda: Julida). Entomologica Scandinavica 16: 27–67.

Enghoff H (1991) A revised cladistic analysis and classification of the millipede order Julida with establishment of four new families and description of a new nemasomatoid genus from Japan. Zeitschrift fuer zoologische Systematik und Evolutionsforschung 29: 241–263.

Enghoff H (1994) Geographical parthenogenesis in millipedes (Diplopoda). Biogeographica 70: 25–31. https://www.researchgate.net/publication/289831304_Geographical_parthenogenesis_in_millipedes_Diplopoda

Hoffman RL (1961) A new genus and subfamily of the diplopod family Nemasomatidae from the Pacific Northwest. Proceedings of the Entomological Society of Washington 63: 58–64. https://www.biodiversitylibrary.org/page/16338831

Hoffman RL (1963) Taxonomic notes on some American Nemasomatid Diplopoda. Transactions of the American Entomological Society 89: 165–182. https://www.jstor.org/stable/25077858

Shelley RM (1994) Revision of the milliped family Paeromopodidae, and elevation of the Aprosphylosomatinae to family status (Julida: Paeromopodoidea). Entomologica Scandinavica 25: 169–214.