Satyrium curiosolus MacDonald, Dupuis, Glasier, Sissons, Moehrenschlager, Shaffer & Sperling, 2025

Satyrium curiosolus MacDonald, Dupuis, Glasier, Sissons, Moehrenschlager, Shaffer & Sperling sp. nov.

Type locality.

Canada: Alberta, Waterton Lakes National Park, Blakiston Fan, 49.068, -113.877.

Type material examined.

Holotype. 1 1 [white label] “ CANADA: Alberta, Waterton Lakes National Park, Blakiston Fan ( Marquis ), 49.068, -113.877 (WGS 84), 14-Jul-2021, J. Glasier; 14008, Saytrium_curiosolus_016 ”; [white label] “ UASM 423537 ”; [red label] “ Holotype Satyrium curiosolus ”. BioSample: SAMN 45172752. GoogleMaps

Paratypes. 1 1 [white label] “ CANADA: Alberta, Waterton Lakes National Park, Blakiston Fan ( Hay Barn ), 49.079, -113.866 (WGS 84), 14-Jul-2021, J. Glasier; 14002, Saytrium_curiosolus_009 ”; [white label] “ UASM 423534 ”. BioSample: SAMN 45172749 GoogleMaps • 1 1 [white label] “ CANADA: Alberta, Waterton Lakes National Park, Blakiston Fan ( Hay Barn ), 49.078, -113.869 (WGS 84), 14-Jul-2021, J. Glasier; 14003, Saytrium_curiosolus_010 ”; [white label] “ UASM 423535 ”. BioSample: SAMN 45172750 GoogleMaps • 1 1 [white label] “ CANADA: Alberta, Waterton Lakes National Park, Blakiston Fan ( Hay Barn ), 49.076, -113.869 (WGS 84), 14-Jul-2021, J. Glasier; 14006, Saytrium_curiosolus_012 ”; [white label] “ UASM 423536 ”. BioSample: SAMN 45172751 GoogleMaps .

Description.

The morphological description follows Mattoon and Austin’s (1998: 685) description of Satyrium fuliginosum semiluna Klots , which is now recognized as Satyrium semiluna semiluna Klots ( Warren 2005).

A small, drab butterfly. As with many Satyrium , wings predominately brownish or dark brown dorsally (fading to light brown with age), lacking any hint of blue, and lacking tails. Males with strong dorsal scent pad of androconial scales, shared with S. semiluna , but lacking in S. fuliginosa (W. H. Edwards) ( Warren 2005). Ventral wing surface light brown with grey overscaling along margins, and large black postmedial spots slightly outlined in white (reduced in hindwings). Females slightly larger and paler ventrally.

Diagnosis.

Males with small wingspan (<25 mm vs> 30 mm) and less conspicuous ventral spotting than S. semiluna ( Kondla 2004) . Due to the cryptic nature of the species, identification without reference to source locality is most reliably achieved by DNA as follows, with representative (see Remarks section) diagnostic single nucleotide polymorphisms (SNPs) that are fixed for S. curiosolus (formatted as scaffold: position [ S. curiosolus allele / S. semiluna allele]: ScvBUXZ _ 1. HRSCAF 10: 1568673 [C / A], 12071375 [C / A], 22597556 [G / C], 33128087 [T / G], 43633436 [G / C], 54341325 [T / A]; ScvBUXZ _ 11. HRSCAF 312: 939246 [C / T], 11508752 [A / T], 23223489 [T / C], 34114361 [T / C]; ScvBUXZ _ 12. HRSCAF 324: 2725346 [G / T], 13277889 [C / A], 23561701 [T / A], 34983585 [G / A]; ScvBUXZ _ 15. HRSCAF 369: 604178 [A / G], 10688359 [A / G], 22742875 [A / G], 33306760 [T / C], 43372888 [A / C]; ScvBUXZ _ 16. HRSCAF 394: 1798098 [A / G], 13584119 [G / C], 24134185 [G / A], 36106687 [A / G]; ScvBUXZ _ 18. HRSCAF 419: 1271585 [C / T], 12498609 [T / A], 22674145 [A / C], 32848269 [A / G], 43126131 [A / G], 53221485 [G / A], 63907163 [T / A]; ScvBUXZ _ 20. HRSCAF 485: 1278399 [C / A], 11291064 [A / G], 22201816 [G / T], 34957432 [C / T], 45290319 [A / G], 56419490 [G / A], 70868124 [T / C], 82626599 [G / C]; ScvBUXZ _ 21. HRSCAF 503: 3759737 [G / A], 14004891 [T / C], 24159643 [A / T], 34796558 [A / G], 46064578 [A / C]; ScvBUXZ _ 22. HRSCAF 557: 1241910 [T / C], 11429001 [A / G], 22696299 [A / G], 32721285 [T / C], 43059425 [T / G], 53074410 [A / G], 63089033 [T / G], 74842831 [G / T]; ScvBUXZ _ 23. HRSCAF 563: 1626681 [A / G], 12005836 [C / A], 22106743 [T / G], 32206731 [A / C], 42322988 [A / C]; ScvBUXZ _ 27. HRSCAF 638: 617786 [A / G], 10908292 [T / G], 20909876 [T / C], 31703436 [A / C], 42607435 [A / G], 52716659 [T / C], 63015994 [A / G]; ScvBUXZ _ 3. HRSCAF 45: 40925 [T / C], 10620232 [A / C], 20622161 [A / C]; ScvBUXZ _ 33. HRSCAF 736: 1025752 [C / T], 11845689 [T / C], 21926431 [A / G], 33073314 [T / C], 43525185 [C / A]; ScvBUXZ _ 36. HRSCAF 762: 496718 [G / T], 12599380 [T / C], 22623129 [A / C], 32789532 [T / G], 43886779 [C / T], 53941324 [T / C]; ScvBUXZ _ 37. HRSCAF 777: 1137238 [A / C], 11176395 [C / T], 21849140 [A / G], 36719032 [G / T], 46746341 [A / C], 57389780 [G / A]; ScvBUXZ _ 4. HRSCAF 59: 2539048 [A / C], 15455375 [T / G], 25460453 [T / C], 35798787 [C / A], 46323982 [A / C], 59292711 [A / G]; ScvBUXZ _ 41. HRSCAF 810: 342264 [A / G], 10823670 [C / T], 21337909 [T / C], 31863338 [G / C], 41915594 [A / T], 52015696 [T / G]; ScvBUXZ _ 48. HRSCAF 855: 2065895 [T / C], 12340828 [G / C], 22489657 [A / G], 33211401 [A / G], 43237667 [T / A]; ScvBUXZ _ 5. HRSCAF 87: 653322 [A / G], 11521727 [C / G], 22249471 [A / G], 32408138 [T / A], 42462727 [T / G], 52471692 [A / G]; ScvBUXZ _ 54. HRSCAF 883: 1953965 [C / A], 12005082 [A / G], 22185366 [C / T], 32223581 [C / T]; ScvBUXZ _ 6. HRSCAF 109: 2728984 [T / C], 14807116 [G / A], 25931083 [T / C]; ScvBUXZ _ 9. HRSCAF 216: 1632867 [C / G], 14935276 [A / G], 26523755 [C / G], 37425842 [T / A]

Genomic sequence of the holotype.

BioSample: SAMN 45172752; whole-genome consensus sequence available on Dryad: https://doi.org/10.5061/dryad.sf 7m 0cgj2.

Distribution.

Currently known only from Blakiston Fan, Alberta, Canada, approximately 300 ha in area.

Seasonality.

Eggs overwinter before hatching in early spring in late April or early May. Larvae can first be found in early May, develop through four instars, pupate in July (at the base of L. argenteus , often under the previous year’s stems in ant galleries), and then emerge after about two weeks of pupation in July to mid-August.

Ecology.

Restricted to Blakiston Fan, a 300 - ha area of course-textured alluvial fan at an elevation of ~ 1,300 m. The habitat of S. curiosolus is short-grass prairie with abundant L. argenteus , L. sericeus , and yellow buckwheat ( Eriogonum flavum Nutt. ?). This habitat differs from that of S. semiluna , in that is it lacking big sagebrush ( A. tridentata ). Satyrium semiluna is associated with A. tridentata to the point that, in the USA, the butterfly’s common name is the Sagebrush Sooty Hairstreak. Another notable difference is that S. semiluna populations generally inhabit hillsides or mountainsides, while S. curiosolus inhabits an alluvial fan in the middle of a montane valley.

Unlike previous reports stating that that S. curiosolus uses both local lupine species as plant hosts ( COSEWIC 2006, 2022; ECCC 2016), our surveys found that they only use L. argenteus . Out of ~ 500 larvae detected in repeated surveys throughout 2020–2024, all were on L. argenteus . Satyrium semiluna populations on the west side of the Rocky Mountains, and presumably those throughout the central USA, feed on L. sericeus . These populations may also feed on L. lepidus ( James and Nunnallee 2011) , but in extensive surveys throughout British Columbia in 2021–2024, we have not observed any such association (Glasier pers. obs.). Satyrium curiosolus larvae feed on new buds and stems at the base of lupines and commonly hide under the woody stems from the previous year when not feeding.

At Blakiston Fan, all S. curiosolus larvae observed in 2021–2024 surveys were closely associated with Lasius ponderosae ant colonies (identified using Glasier et al. 2013 and Schär et al. 2022). Ants groomed and protected the larvae, and larvae were observed to retreat into ant colonies when threatened. Other ant species seen interacting with larvae at Blakiston Fan include Formica argentea and Formica lasioides (ants identified using Glasier et al. 2013. However, these interactions appeared to be more opportunistic, as these larvae observed were still primarily associated with a L. ponderosae colony. We have also observed S. curiosolus larvae pupating in the galleries of L. ponderosae colonies at the base of Lupinus argenteus plants. During our butterfly surveys in 2021–2024 in British Columbia, no Lasius species were found attending S. semiluna larvae. Instead, Camponotus vicinus , Formica obscuripes , and Formica argentea were observed interacting with larvae, and several pupae were found in a Camponotus vicinus nest at the base of a L. sericeus . In California, Camponotus and Formica attendants were also reported ( Runquist 2012).

Satyrium curiosolus fluctuates in abundance from year to year, with genomically based estimates of contemporary effective population size (N e) around 500 ( MacDonald et al. 2025) and surveys suggesting that between 1,000 and 10,000 adults fly annually ( COSEWIC 2006, 2022; unpublished data). Based on our observations from 2020–2024, the S. curiosolus flight period occurs during July to mid-August and lasts about two weeks. Adults are most frequently observed as they perch, sunning themselves on buckwheats, lupines, and shrubby cinquefoil ( Dasiphora fruticosa ). Males tend to spend more time on alpine buckwheat, while females tend to spend more time on lupines. Mating occurs at any time of day and may last several hours. Females lay an unknown total number of eggs but have been observed laying eggs singly or in small clusters, in the soil around the base of L. argenteus and / or near the entrance of L. ponderosae nests.

Etymology.

The specific epithet curiosolus derives from the Latin “ curiosus ” meaning curious and “ solus ” meaning to be alone or isolated, and it is to be treated as a noun in apposition. We suggest the common name “ Curiously Isolated Hairstreak ”.

Remarks.

Using our reference genome assembly (NCBI JASDAZ 000000000) and whole-genome resequencing data for 15 individuals, we identified 21,985 SNPs across 22 scaffolds that were fixed for alternate nucleotides between individuals from Alberta and those from Montana and British Columbia. The 117 SNPs included in this description result from thinning to one SNP per 10 Mb (using -- thin option in vcftools v 0.1. 16, Danecek et al. 2011) to ensure that they are evenly spaced across the genome and likely physically unlinked. DNA barcodes (mitochondrial gene cytochrome oxidase subunit I) have been shown to be identical between populations of S. semiluna from Alberta, British Columbia, and Washington ( COSEWIC 2006), and haplotype sharing (in cytochrome oxidase subunit II) has been observed more broadly between S. semiluna and S. fuliginosa ( Runquist 2012) ; both observations suggest that mitochondrial / nuclear discordance exists within the genus. Taken together with other systematic studies with broader taxonomic sampling ( Robbins et al. 2022), these data also provide support for th inclusion of S. curiosolus within Satyrium . Nuclear whole-genome consensus sequences for each individual of the type series are available at: https://doi.org/10.5061/dryad.sf7m0cgj2.