Agyneta uta Chamberlin 1920
Creators: name: Dupérré, Nadine
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Linyphiidae
Agyneta
Agyneta uta

description: Agyneta uta (Chamberlin 1920)
Figs 165–171, map 9
Microneta uta Chamberlin 1920: 196, f. 20.4. (Description 3).
Microneta anopla Chamberlin & Ivie 1933: 35, pl. 9, f. 96–98. (Description Ƥ). (Holotype 3, allotype Ƥ from Utah: Raft R. Mts., Clear Cr., 9/4/32, Chamberlin & Ivie, AMNH). Examined.
Meioneta uta van Helsdingen 1973: 7, 10. (Transferred 3 from Microneta, synonymized Ƥ).
Agyneta uta Buckle et al. 2001: 101. (Transferred from Meioneta).
Type material: Microneta uta Chamberlin 1920, 3 HOLOTYPE from Utah, Logan Canyon. R.V. Chamberlin Coll. (unique number 23420). MCZ, EXAMINED.
Diagnosis: Males are differentiated from all Agyneta species by their short, triangular, slightly dentate lamella characteristica (Fig. 165). From A. simplex by the absence of a cymbial tubercles (Fig. 166). Females are differentiated from all species by the proximal part of scape tinted with a grayish mark (Fig. 169). See A. simplex diagnosis to distinguish from the latter.
Description: Male: Total length 1.41; carapace length 0.64, width 0.49.
CEPHALOTHORAX: Carapace dark brown, shiny, finely reticulate; suffused with dark gray along margin, radiating lines; trident mark often present. Sternum dark brown strongly suffused with dark gray. Clypeus height 1. Chelicerae brown apical part lighter, with transverse dark gray band, not excavated; seta-tipped tubercles absent; promargin three denticles, retromargin three denticles; without projections near base of fang. Cheliceral stridulatory organ ~34 striae, well spaced getting closer together basally. ABDOMEN: Uniformly dark gray. LEGS: Yellow; leg I total length: 2.04; leg III total length: 1.60; Tm I: 0.32, Tm IV: absent. GENITALIA: Palpal retrolateral tibial apophysis short, rounded and smooth; dorsal tibial apophysis absent; two retrolateral trichobothria and a dorsal one (Fig. 165). Cymbium triangular; glabrous depression present (Fig. 165); cymbial tubercles absent; prolateral notch absent (Fig. 166). Paracymbium apical pocket small, anterior pocket curved and deep, not reaching the short and curved posterior pocket (Fig. 165). Embolus tip pointed, straight, with small retrolateral extension; Fickert’s gland absent; ventral lamella pointed, transparent; thumb short reaching below the embolus proper (Fig. 167). Embolus proper set apically, both part of equal size (Fig. 167). Anterior terminal apophysis narrow with no protrusions; posterior terminal apophysis striate; lamella characteristica large, ending in a wide curved tip with numerous spines (Fig. 168).
Female: Total length 2.01; carapace length 0.76, width 0.51.
MAP. 9. Localities of Agyneta uta (Chamberlin1920).
CEPHALOTHORAX: Same coloration as male. Chelicerae yellow; promargin four teeth, retromargin four denticles. Clypeus height 1. Cheliceral stridulatory organ ~29 striae, well spaced getting closer together basally. ABDOMEN: Same as male. LEGS: Same as male; palpal tarsal claw absent; leg I total length: 2.49; leg III total length: 1.84; Tm I: 0.24, Tm IV: absent. GENITALIA: Epigynum with proximal part of scape triangular tinted with grayish mark; epigynal slits oval; pit hook depression absent (Fig. 169); lateral lobes short and wide; stretcher seemingly absent; pit small (Fig. 170). Median part of scape short and wide; genital pores situated at base of lateral lobes pockets (Fig. 171). Internal genitalia with an elongated ventral receptacula and an oval dorsal one (Figs 170, 171).
Other material examined: USA: California: 8km North of Jonesville, 06.ix.1935, 335Ƥ, R. Chamberlin (AMNH); Bray, 08.ix.1935, 435Ƥ, R. Chamberlin (AMNH); Hay Creek, 07.ix.1935, 1Ƥ, R. Chamberlin (AMNH); Silver Divide, N of Graveyard Lakes, 14.viii.1959, R. Chamberlin (AMNH). Colorado: Florissant, Petrified Forest Area, 11.viii. 1973, 2430m, 13, P. Arnaud (CAS). Idaho: Indian Valley, 6km SE town, 21.viii.1932, 232Ƥ, W. Ivie (AMNH); Lost Lake, 27.vii.1939, 23 (AMNH); NE McCall, 31.v.1944, 1Ƥ, W. Ivie (AMNH); Mesa, 05.viii.1943, 13, W. Ivie (AMNH); 3km NE Fruitland, 20.vi.1943, 13, W. Ivie (AMNH); NE Fruitland, 20.vi.1943, 13, 10–25.ix.1943, 1033Ƥ, W. Ivie (AMNH); Notus, 25.viii.1933, 131Ƥ, 18.ix.1933, 43, W. Ivie (AMNH); Payette Lake (north side), 20.vi.1953, 13, W. Ivie (AMNH); Snake River Bridge, NW Fruitland, 16.ix.1943, 23, W. Ivie (AMNH); Thousand Springs, vii.1938, across river, 236Ƥ, W. Ivie (AMNH). Nebraska: Ruby Valley, ix.1937, 331Ƥ, R. Chamberlin (AMNH). New Mexico: 9-12km E Canjillon, 131Ƥ, C. Hoff (AMNH); Glorieta Mesa near Rowe, 133Ƥ, C. Hoff (AMNH); Los Alamos, 03.vi.1986, 13, D. Lowrie (DBC); S- 96 W Emory Pass, 4Ƥ, C. Clayton (AMNH). Oregon: Blue Mountains, v.1960, 1 Ƥ, J. Schuh (AMNH); Lava River Caves State Park, 14.ix.1965, 333Ƥ, J., W. Ivie (AMNH); Umatilla National Forest, Ruckela Junction Upper slope, 14.ix. 1965, 1341m, lower crown foliage, 1Ƥ, J. R. Mason (USNM). Utah: 17km N Kamar, 04.xi.1939, 3Ƥ, D. Mulaik (AMNH); Brighton, 20.xi. 1939, 2651m, 833Ƥ, D. Mulaik (AMNH); Callas, 19.ix.1927, 131Ƥ, R. Chamberlin (AMNH); Clear Creek, Raft River Mountains, 04.ix.1932, 837Ƥ, R. Chamberlin (AMNH); Dove Creek, Raft River Mountains, 09.ix.1932, among fallen willow leaves 535Ƥ, R. Chamberlin (AMNH); East Canyon, 14.vi.1942, 133Ƥ, W. Ivie (AMNH); Fillmore Canyon, 22.ix.1935, 235Ƥ, R. Chamberlin (AMNH); Grouse Creek, 08.ix.1932, 131Ƥ, W. Ivie (AMNH); Henry Mountains, 09-12.ix.1929, 332Ƥ, R. Chamberlin (AMNH); Joseph, 26.viii.1927, 2Ƥ, R. Chamberlin (AMNH); North Fork of Provo River, Cobble Rest Camp, 24.viii. 1931,1Ƥ, W. Ivie (AMNH); Park Valley, 09.ix.1932, 1Ƥ, R. Chamberlin (AMNH); Payson Canyon, 15.iv.1934, 3Ƥ, W. Ivie (AMNH); Richfield, 21.ix.1935, 2Ƥ, R. Chamberlin (AMNH); Salt Lake City, 08.xi.1940, 231Ƥ, W. Ivie (AMNH); Salt Lake City, Dry Canyon, 22.ii.1933, under grass on hillside, 131Ƥ, W. Ivie (AMNH); Salt Lake City, Mill Creek Canyon, 05.xi. 1939, 2438m, 23, D. Mulaik (AMNH); Smith and Morehouse Canyon, 06.vi.1934, 1Ƥ, W. Ivie (AMNH); Willow Springs, 08.x.1927, 131Ƥ, R. Chamberlin (AMNH); Zion National Park, 1927, 1Ƥ (AMNH). Washington: Ingersoll Road [47.245N, 129.249W], 1146m, 11.viii.2004, Abies grandis foliage, 13, R. Crawford (UWBM); Kamiak Butte [46.867N, 117.155W] 26.viii–26.xii.1994, pitfalls, forest, 926m, 23, J. Bergdahl (UWBM); Manson, Morse Road, [47.917N, 120.125W] 21.ix.1982, riparian duff, 13, D. Caroll (CAS); North Fork of Colockum [47.24N, 120.296W] 10.vii. 2004, 1499m, Larix / Pinus contorta foliage, 132Ƥ, R. Crawford (UWBM); Richland, 17.ix.1935, 4Ƥ, R. Chamberlin (AMNH); South of Spirit Lake [46.249N, 122.162W] 0 8–09.vi. 1984, 1103m, pitfalls, volcanic rocks, 13, R. Sugg (UWBM).
Distribution: Western USA.
The fillmorana group includes six species, A. fillmorana (Chamberlin 1919), A. darrelli n. sp., A. emertoni (Roewer 1942), A. bucklei n. sp., A. erinacea n. sp. and A. crawfordi n. sp., found in western North America.
All species within the group shared two unique characters; the male cymbium has a retrolateral fold (Fig. 172) and the dorsal part of the embolus proper is serrated, crest-like and connected to the tip of embolus (Figs 27, 174). Within the group, A. fillmorana, A. emertoni, A. darrelli are more closely related and share several characteristics; a reduced lamella characteristica, palpal tibia with two retrolateral trichobothria and the paracymbium with only an apical pocket and no posterior pockets (Figs 172, 185, 195). In addition, the male embolus has a long thumb, extending beyond the embolus proper and the ventral lamella of the embolus, is transparent and rugose (Figs 174, 187).
Only the holotype specimen of A. emertoni was available for study, the color was faded, legs were missing or damaged. As such no detailed examination of the embolus and radical division was possible. Based on the presence of the retrolateral fold of the cymbium, the well serrated dorsal part of the embolus proper, easily visible in prolateral view (Fig. 196), I feel confident that A. emertoni belongs in this group. Furthermore the presence of only an apical pocket on the paracymbium, and the absence of a basal enlarged plate of the embolus clearly shows its relation to A. fillmorana and A. darrelli.
In A. bucklei, A. erinacea and A. crawfordi, the paracymbium has an apical pocket
and a posterior pocket, the palpal tibia with only one retrolateral trichobothria (Figs 197, 202, 209). Additionally, the thumb is short and at most reaching the base of the embolus proper, the ventral lamella is enlarged basally in a plate with small spines and the embolus has long spikes retro-ventrally (Figs 199, 204, 211), interestingly those spikes are also found in A. serrata, A. semipallida (Figs 445, 531).
A. fillmorana is a fascinating species that displays an extraordinary range of morphs, in reference to the male overall size and cheliceral morphology. Chamberlin first described in 1919, Bathyphantes fillmoranus based on a female from Fillmore Canyon, Utah (later transferred to Meioneta by Ivie in 1969). Then in 1943, Chamberlin & Ivie described a new species based on a male from City Creek Canyon, Utah, as Gnathantes ferosa. The extreme size of the male chelicerae led them to believe that this was another genus and therfore they erected the genus Gnathantes. When studying the palpal configuration, it is clear that this is a member of the genus Agyneta. The match of the two sexes together would have been difficult for Chamberlin & Ivie since the males and females were not collected at the same localities at that time. After studying many specimens, from different localities, it is apparent that Gnathantes ferosa is the male of A. fillmorana, as many males and females have been collected together. Moreover, I also found small males of normal size, with normal chelicerae and with the same palpal configuration has G. f e ro s a excluding small variation that falls within the range of variation observed in other species of Agyneta. One particular sample from California contained three different males morphs, one large male with greatly enlarged chelicerae (Fig. 179), one medium size male (Fig. 180) and a really small male. After detailed study of the male palp, embolus and radical division of those specimens I am convinced that this is a case of polymorphism. Some other cases of male size dimorphism and/or polymorphism (cheliceral and palp enlargement) have also been reported for spiders (Vink et al. 2011).
description: Published as part of Dupérré, Nadine, 2013, Taxonomic revision of the spider genera Agyneta and Tennesseellum (Araneae, Linyphiidae) of North America north of Mexico with a study of the embolic division within Micronetinae sensu Saaristo & Tanasevitch 1996, pp. 1-189 in Zootaxa 3674 (1) on pages 56-59, DOI: 10.11646/zootaxa.3674.1.1, http://zenodo.org/record/283954