Siskiyu armilla, Hedin & Ramírez & Monjaraz-Ruedas, 2025

Siskiyu armilla sp. nov.

Figs 1 View Figure 1 , 6 View Figure 6 , 7 View Figure 7 , 10 View Figure 10

Material examined.

Holotype: – Oregon, Josephine Co. • ♂; Hwy 46, 8.3 mi. E Cave Junction, near Nelson Creek, along Sucker Creek ; 42.1643, - 123.5008; 15 Aug. 2006; coll. M. Hedin, R. Keith, M. McCormack; MCH 06_115 ; SDSU_G 1090 GoogleMaps ; Paratypes: – California, Siskiyou Co. • 2 ♀; West Fork Beaver Creek, confluence with Little Soda Creek , Forest Road 47 N 01 ; 41.9455, - 122.8334; 18 Apr. 2006; coll. M. Hedin; MCH 06_066 ; SDSU_G 1086 , SDSU_G 1086 A GoogleMaps ; • 3 ♀; Matthews Creek campground, on Salmon River ; 41.1863, - 123.2148; 10–12 July 2005; coll. M. Hedin; MCH 05_029 GoogleMaps .

Additional material.

USA – Oregon, Josephine Co. • ♂; Hwy 46, 8.3 mi. E Cave Junction, near Nelson Creek, along Sucker Creek ; 42.1643, - 123.5008; 15 Aug. 2006; coll. M. Hedin, R. Keith, M. McCormack; MCH 06_115 ; SDSU_G 1089 GoogleMaps ; – California, Siskiyou Co. • ♀; West Fork Beaver Creek, confluence with Little Soda Creek , Forest Road 47 N 01 ; 41.9455, - 122.8334; 18 Apr. 2006; coll. M. Hedin; MCH 06_066 ; SDSU_G 1087 GoogleMaps ; • ♀; Beaver Creek Rd, near Beaver Creek campground ; 41.9238, - 122.8321; 18 Apr. 2006; coll. M. Hedin; MCH 06_065 ; SDSU_G 1088 GoogleMaps ; • several immatures; FR 11, along Beaver Creek, below confluence with Fishtrap Creek ; 41.9426, - 122.8024; 22 July 2024; coll. M. Hedin, O. Hedin; MCH 24_057 GoogleMaps ; • ♀; Matthews Creek campground, on Salmon River ; 41.1863, - 123.2148; 10–12 July 2005; coll. M. Hedin; MCH 05_029 ; SDSU_G 0570 GoogleMaps .

Etymology.

armilla (L., a ring, bracelet), from the conspicuous ring-like patellar fracture lines (Fig. 1 C View Figure 1 ).

Description of ♂ holotype.

( SDSU _G 1090 ; Fig. 6 A, B View Figure 6 ) Color in alcohol pale cream to white, fangs slightly darker. Carapace essentially bare, unmarked; abdomen dusky dorsally and ventrally, slightly darker dorsal longitudinal bars posteriorly. Total length 2.3, carapace length 1.15, carapace width 0.85, cephalic region width 0.5, posterior eye row width 0.325. Eye diameters AME: ALE: PME: PLE = 0.025: 0.075: 0.05: 0.075. Leg I article lengths (1.65, 0.5, 1.9, 1.6, 0.9 = 6.4), leg IV article lengths (1.45, 0.4, 1.5, 1.5, 0.8 = 5.6). Leg macrosetae sparse, one or two on tibia III and V (prolateral and ventral), and metatarsus III and IV (prolateral and ventral, distal cluster).

Male palp with shelf-like distal patellar apophysis. Basal retrolateral tibial apophysis (RTA) a minute spike, with sclerotized parallel weak ridges bordering a slight excavation, extending to a short and blade-like distal RTA. Bulb with a short dorsal tegular process at base of whip-like embolus which extends to ~ 3 o’clock then projects ventrally, protected by conductor. Triangular conductor with spatulate distal, and sharply pointed basal lobes. Beak-like ventral lobe of conductor enclosing embolus. Median apophysis absent. Cymbium elongate, distal projection approximately as long as bulb.

Description of ♀ paratype.

( SDSU _G 1086 A; Fig. 7 A – E View Figure 7 ) Color in alcohol pale cream to orange, fangs slightly darker. Carapace essentially bare, unmarked; abdomen without markings. Total length 2.9, carapace length 1.3, carapace width 0.925, cephalic region width 0.55, posterior eye row width 0.325. Eye diameters AME: ALE: PME: PLE = 0.025: 1: 0.05: 1. Leg I article lengths (1.57, 0.5, 1.6, 1.4, 0.9 = 5.9), leg IV article lengths (1.55, 0.4, 1.5, 1.5, 0.7 = 5.7). Leg macrosetae sparse, 1 on dorsal patella III and IV, 1–2 on tibia III and V (prolateral and ventral), and metatarsus III and IV (prolateral and ventral, distal cluster).

Epigynal plate with a semicircular ridge along the anterior edge (Fig. 7 D, E View Figure 7 ). Paired lateral ear-shaped copulatory openings, sclerotized laterally and ventrally, lie ventral to this ridge. Thin copulatory ducts arise from copulatory openings and loop dorsally to meet in the midline, then extend ventrally in parallel, diverge at the bottom, then extend dorsally to connect with spermathecae. Paired spermathecae bilobed, medial lobe slightly smaller and more oval-shaped than larger and more spherical lateral lobes, connected by a short, looped duct. Fertilization ducts short and indistinct, extending ventrally from medial lobes.

Variation.

Female epigyna from the three geographically distant known locations (Cave Junction, Beaver Creek, Salmon River, Fig. 10 View Figure 10 ) are very similar in detail.

Distribution and natural history.

Known from five separate locations (three in close vicinity near Beaver Creek), spanning from northern records near Cave Junction, Oregon to southern records along the Salmon River in Siskiyou County, California (Fig. 10 View Figure 10 ). All collecting events are from mixed coniferous forests (including Pseudotsuga menziesii , Pinus sp. , Arbutus menziesii ) at mid-elevations (550–800 m) in the Klamath-Siskiyou Mountains. We anticipate additional populations in intervening and neighboring locations.

Spiders found abundantly beneath rocks in shaded rock piles, often under rocks lying directly on the surface, versus deeper in rock piles. Spiders were generally found without associated webs, although some subadult specimens found along Beaver Creek at Fishtrap Creek ( MCH 24_057 ) were found near sparse webbing (Fig. 1 D View Figure 1 ). Adults have been collected in April, July, and August; only subadults were found during the July collecting event at Fishtrap Creek ( MCH 24_057 ).

Comments.

Discovery of this distinctive taxon adds to our knowledge of the highly diverse flora and fauna of the Klamath-Siskiyou Mountains ( Kauffmann and Garwood 2022). Other globally rare and endemic spider taxa, reflecting also the high phylogenetic diversity of the region, include Hypochilus kastoni Platnick, 1987 , Trogloraptor marchingtoni Griswold, Audisio & Ledford, 2012 , and Calileptoneta sylva (Chamberlin & Ivie, 1942) . Additional efforts are needed to fully understand the arthropod biodiversity of this unique region.