Antrodiaetus metapacificus, Cokendolpher, James C., Peck, Robert W. & Niwa, Christine G., 2005

Cokendolpher, James C., Peck, Robert W. & Niwa, Christine G., 2005, Mygalomorph spiders from southwestern Oregon, USA, with descriptions of four new species, Zootaxa 1058, pp. 1-34 : 26-29

Antrodiaetus metapacificus n. sp.

Figs. 1 , 7 , 14 , 28–29 , 37 , 44–45 , 52

Type Material. Oregon (all collected on 9 Oct. 2002 by Niwa and Peck USFS): Josephine County, Galice Ranger District, Siskiyou National Forest, N42°32’52”, W123°37’59” (652 m elevation), 1 male holotype ( NMNH), 2 male paratypes (1, JCC; 1, WFIC).

Diagnosis. This species differs from many members of the genus by having the three opisthosomal sclerotized patches fused into a single scutum ( Fig. 14 ). Others with this characteristic occur in Japan, eastern North America, and the Pacific Northwest of the USA (Oregon: A. coylei n. sp. and northeastern Washington: A. cerberus Coyle ). Antrodiaetus metapacificus n. sp. can be distinguished from A. coylei n. sp. by lacking a small cheliceral distodorsal projection ( Fig. 37 ) and differs from A. cerberus by the overall smaller size. The prosomal dorsal shield length is 5.2–5.4 in A. cerberus and 3.9–4.7 in the new species.

Etymology. Meta (Greek) means, among other things, to be derivative or related. In this case it is used to show the relationship of this species to A. pacificus . This species will key to A. pacificus in Coyle (1971). This primarily based on the notion that A. pacificus consists of individuals with less than 30% of the male tibia I macrosetae being ensiform. The percentage is actually much lower (0–3%) in the western examples of A. pacificus (see comments below under that species).

Distribution. Known only from a single location within the Galice Ranger District, Siskiyou National Forest, Josephine County, Oregon ( Fig. 1 ).

Description. Female unknown. Male (n = 3): body small, total body length 8.45 (6.35, 7.9), and yellowish­brown, appendages and sclerotized patches on opisthosoma more evenly light brown with leg I patella to tarsus reddish­brown, dark brown pigment encircling anterior median eyes and between posterior median eyes and lateral eyes.

Dorsal shield of the prosoma 4.5 (3.95, 4.7) long, 3.2 (2.6, 3.35) wide, with setae scattered sparsely over pars thoracica except denser along lateral and posterior borders.

Opisthosoma 3.95 (2.4, 3.2) long, 2.4 (2.75, 3.2) wide; all three dorsal sclerotized patches fused into single scutum (in holotype the area after the first is almost divided, but this junction is undetectable in paratypes) ( Fig. 14 ); male genital plate with sclerotized parts undivided, straight to recurved ( Figs. 28–29 ).

Chelicera with large area on upper ectal surface without setae; without distodorsal projection ( Fig. 37 ).

Palp with tibia swollen. Tibia 2–2.4 times longer than wide; widest in proximal third; 2.6 (2.05, 2.3) long, 1.28 (0.85, 1.05) wide. Tip of outer conductor sclerite ( Fig. 52 ) roundly pointed; closely appressed to inner conductor sclerite. Tip of inner conductor sclerite well sclerotized and not curved.

Leg I ( Figs. 44–45 ) without any segment being greatly enlarged or modified with processes; femur 3.9 (3.35, 3.65) long, patella 1.7 (1.5, 1.85) long, tibia 2.55 (2.25, 2.7) long, 0.5 (0.75, 0.9) wide, metatarsus 3.35 (2.8, 3.05) long, tarsus 2.4 (1.65, 1.8) long. Tibia I with relatively dense group of prolateral macrosetae medially (not reaching distal end of segment). Tibia I with relatively dense group of prolateral macrosetae medially (not reaching distal end of segment): 31 (9 ensiform) [28 (8 ensiform), 35 (10 ensiform)] macrosetae. Tibia I with 6 (6,7) medial (not extending to distal end) macrosetae ventrolaterally, the longest seta about width of tibia (noticeably longer than any prolateral macrosetae). Tibia I without large heavy macrosetae ventrally; tibia and metatarsus I not swollen in lateral view; metatarsus I slightly sinuous to straight, without macroseta ventrally; other setae ventrally on metatarsus I = 2 times greatest width of segment.

Wandering Activity. This species was only recorded on 9 October 2001 ( Fig. 7 ).

Comments. Antrodiaetus metapacificus n. sp. was found at a single site within the Douglas­fir/dry shrub plant association of the western Siskiyou Mountains. The overstory of this relatively low elevation site (652 m) was dominated by Douglas­fir (36% cover) but also included incense­cedar (12%) and Oregon ash ( Fraxinus latifolia Bentham ) (5%). Twenty­three understory plant species were recorded at the site, with pacific madrone ( Arbutus menziesii Pursh ) (6%), Oregon ash (5%) and tanoak (4%) most common. The site faced SE and had a slope of approximately 24°.

Figures

FIGURE 1. Map of Oregon showing study areas within the Siskiyou and Cascade Mountains and a list of mygalomorph species found in each area [relief map modified from: http: // www. flag. wr. usgs. gov / USGSFlag / Data / maps / Oregon. gif (accessed 31 August 2005)]. Insert shows position of region within the USA.

FIGURE 7. Abundance of adult male Antrodiaetus spiders collected in pitfall traps from southwestern Oregon.

FIGURES 12 – 15. Dorsal view of male body. 12, Antrodiaetus coylei n. sp.; 13, Antrodiaetus effeminatus n. sp.; 14, Antrodiaetus metapacificus n. sp.; 15, Antrodiaetus pacificus (Simon). Not to scale; see text for approximate sizes of the different species. Arrows indicate sclerotized patches.

FIGURES 22 – 33. Genital plates of males. 22 – 23, Antrodiaetus ashlandensis n. sp.; 24 – 25, Antrodiaetus coylei n. sp.; 26 – 27, Antrodiaetus effeminatus n. sp.; 28 – 29, Antrodiaetus metapacificus n. sp.; 30, Antrodiaetus montanus (Chamberlin & Ivie); 31, Antrodiaetus occultus Coyle; 32, Antrodiaetus pacificus (Simon); 33, Antrodiaetus pugnax (Chamberlin). Inserts emphasize sclerotized regions. Scale line = 0.5 mm.

FIGURES 34 – 37. Ectal view of male left chelicera. 34, Antrodiaetus ashlandensis n. sp.; 35, Antrodiaetus coylei n. sp.; 36, Antrodiaetus effeminatus n. sp.; 37, Antrodiaetus metapacificus n. sp. Scale lines = 0.5 mm.

FIGURES 42 – 45. Male left tibia I and metatarsus I. 42 – 43, Antrodiaetus effeminatus n. sp. (42, prolateral view; 43, ventral view). 44 – 45, Antrodiaetus metapacificus n. sp. (44, prolateral view; 45, ventral view). Scales = 0.5 mm in 0.1 mm divisions.

FIGURES 49 – 52. Prolateral view of entire palp (left) and view of tip after palp rotated 90 ° on longitudinal axis of distal half of inner conductor sclerite. 49, Antrodiaetus ashlandensis n. sp.; 50, Antrodiaetus coylei n. sp.; 51, Antrodiaetus effeminatus n. sp.; 52, metapacificus n. sp. Scale lines = 0.1 mm.