Taracus ubicki Shear

Shear, William A. & Warfel, Joseph G., 2016, The harvestman genus Taracus Simon 1879, and the new genus Oskoron (Opiliones: Ischyropsalidoidea: Taracidae), Zootaxa 4180 (1), pp. 1-71: 53-56

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Taracus ubicki Shear

new species

Taracus ubicki Shear   , new species

Figs. 116–125 View FIGURES 116 – 126 , Map 7

Types. Male holotype, female and male paratypes ( CAS) from Tranquility, 1.5 mi south of Caspar, 300’ asl, Mendocino Co., California, collected 18 September 1990 by Darrell Ubick. “Tranquility” is a privately owned ranch once operated as a nature reserve, at N39.3444°, W123.802° (D Ubick, pers. comm. 2013).

Diagnosis. Taracus ubicki   is very similar to T. pallipes   , but the latter is not known to occur in California. Taracus ubicki   is also on average only about 4/5 the body length of T. pallipes   , and has correspondingly shorter legs. Males of ubicki   can be separated from those of pallipes   by the much smoother second cheliceral segment, the larger sensory cone and by the longer, narrower aculeus of the penis which lacks a distal hook; females of ubicki   differ from those of pallipes   in having scutum laminatum, that the lip of the genital operculum is not heavily sclerotized, the sensory cone is significantly larger, and the chelicerae are relatively longer and smoother.

Etymology. This species is named for CAS arachnologist and harvestman specialist Darrell Ubick, who collected the types and other material and whose aid was invaluable in the completion of this project.

Description. Male from near Caspar, Mendocino Co., California: Total length, 4.70 mm. Carapace dark brown, prominent long, black “hash marks” on either side of ocularium, prominent slit sense organ just anterior, lateral to ocularium, margins of carapace well-defined; strongly domed; midline sulcus extends from anterior margin to ocularium. Ocularium as wide as long, rounded, with three or four small setae on low tubercles above each eye; eyes large, black, ringed with black pigment. Metapelitidium strongly sclerotized, partly merged with carapace, narrow, without setae, posterior margin well-marked; sensory cone white, tipped brown, acute (Fig.), distinct from margin of carapace, no socket apparent. Metapeltidium separated from abdominal scutum by wide area of white cuticle. Abdomen soft, white or pale tan base color; with scutum parvum but lateral margins of scutum irregular; scutum set with rows of small black setae on prominent raised nodules, these rows distinct anteriorly, becoming irregular posterior on scutum; posterior margin of scutum irregular, posterior dorsal sclerites represented by irregular sclerotized patches ( Figs. 122, 123 View FIGURES 116 – 126 ). Ventrally, coxae pale yellowish tan, unspotted. Palpal coxae with numerous stout setae on distinct tubercles, first leg coxae similar with strong, black setae on tubercles; other leg coxae lacking tubercles. No indication of thoracic sternum. Genital operculum apically rounded, sparsely setose, pale yellowish tan, unspotted, with sclerotized distal lip. Abdominal sternites unsclerotized, each with single row of small, acute setae.

Chelicerae ( Figs. 125, 126 View FIGURES 116 – 126 ) 8.83 mm long, black. Basal article 4.05 mm long, 0.55 mm wide (L/W = 7.36); second article 4.78 mm long, 0.67 mm wide (L/W = 7.13). Basal article with prominent mediobasal knob, setatipped tubercles sparsely distributed in basal half, ventral row of tubercles extends less than half length of article, fewer tubercles dorsally; second article with almost smooth, small, low, rounded seta-tipped tubercles ranged in about four irregular rows, tubercles more widely spaced and smaller distally. Fixed and movable fingers with paired, articulating triangular teeth, narrow, acute tips of fingers cross each other at rest.

Palpi ( Fig. 117 View FIGURES 116 – 126 ) pale, shaded slightly darker distally, total length 8.75 mm, relatively slender; trochanter with three or four small seta-tipped tubercles, femur with regularly spaced slender setae, not set on tubercles. Patella not swollen. Lengths of articles as given in Table 20. Legs long, thin; yellowish tan, unspotted. Autospasy suture of femur distinct on all legs. Tibiae without false articulations, metatarsal false articulations on second legs only, about 15. Total lengths in mm of legs 1–4: 9.86, 15.84, 8.73, 12.08. Measurements of leg articles given in Table 20.

Penis ( Figs. 118, 119 View FIGURES 116 – 126 ) 2.19 mm long, 0.38 mm wide (L/W = 5.76), sides of shaft straight; glans slightly swollen, abruptly tapering to long, thin aculeus with small accessory process; aculeus with subtending crown of setae incomplete ventrally; densely setose dorsally; shaft with many scattered small setae distally. Ventrally, glans with distinct triangular ventral plate.

Female from near near Caspar, Mendocino Co., California: Total length, 5.4 mm. Carapace medium to dark brown to black. Metapeltidium not sclerotized; without setae; sensory cone long, acute. Abdomen pale tan, heavily shaded purplish brown, with sparsely scattered, low, sclerotized plaques bearing single or multiple setae; plaques of first two abdominal areas coalesced in midline, on more posterior areas two larger plaques on either side of midline, between these, irregularly arranged smaller plaques ( Figs. 120, 121 View FIGURES 116 – 126 ). Genital operculum with heavily sclerotized lip, sclerotized ventral plate.

Chelicerae 9.28 mm long, basal article 3.90 mm long, 0.52 mm wide (L/W = 7.5); second article ( Fig. 124 View FIGURES 116 – 126 ) 5.38 mm long, 0.76 mm wide (L/W = 7.1). Total length of palpus ( Fig. 115 View FIGURES 106 – 115 ), 7.84 mm; palpal trochanter with prominent seta-tipped tubercles, patella of palpus not swollen, femoral setae not on tubercles. Total lengths in mm of legs 1–4: 8.47, 14,44, 8.99, 12.44; lengths of leg and palpal articles as given in Table 21. Second leg metatarsus with only about five vaguely indicated false articulations, none in other legs. Legs may be sparsely spotted. Ovipositor typical. Other characters as in male.

Distribution. All specimens CAS except as noted. CALIFORNIA: Del Norte Co.: Fort Dick, 31 September 1959, V. Roth, juv. ( AMNH). Humboldt Co.: Prarie Creek Redwoods State Park, 8 September 1958, L. Smith, juv. ( AMNH); 14 mi east of Blue Lake, 19 September 1953, R. Schuster, juv. ( AMNH). Marin Co.: 12990 Sir Francis Drake Blvd., Inverness, N38°06’ 686” W122°51’ 907”, 16 February 2004, W. Leonard, m (WAS); near Muir Woods, 21 August 1965. V. Lee, T. Briggs, juv.; Mill Valley, June 1952, juv. Mendocino Co.: Mendocino, W123°47’, N39°18’, 10 October 1954, J. Helfer, juv.; 2 mi north of Piercy, 19 August 1959, W. Gertsch, V. Roth, juv. ( AMNH); Caspar Creek, 1 mi southeast of Caspar, 13 September 1961, W. Gertsch, W. Ivie, juv. ( AMNH); Little River, 7 June 1955, J. Helfer, juvs. ( AMNH). Modoc Co.: Joseph Creek, 15 mi north of Alturas, 17 June 1954, R. Schuster, juvs. ( AMNH) San Mateo Co.: San Mateo Memorial Park, 2 July 1967, T. Briggs, juv.; Butano Creek, 1 mi from Cloverdale Road, San Mateo, 15 August 1965, juv.; Woodside, 5 July 1958, V. Roth, W. Gertsch, juvs. ( AMNH). Santa Cruz Co.: 0.2 mi south of Davenport Quarry, 11 June 1966, T. Briggs, juv.; Mt. Harmon, July 1908, “Blaisdell,” juv.; Empire Cave, Santa Cruz, 17 September 1966, V. Lee, juv.; Stern’s Cave, Santa Cruz, 15 September 1970, T. Briggs, juv. Siskiyou Co.: Planetary Dairy Cave, 15 mi. west of Ft. Jones, 29 April 1979, D. C. Rudolph et al., ♀; Skunk Hollow Cave, 15 mi. west of Ft. Jones, 29 April 1979, D. C. Rudolph et al., ♀. Sonoma Co   : 0.7 mi east of Fort Ross on Fort Ross Road, Russian Trough, 250’ asl, N 38°32’ W123°14’, 21 June 1996, D. H. Kavanaugh, juvs.; Pine Glade Road, 1 mi northeast of Monte Rio, 6 November 1999, D. Ubick, ♀; Salt Point State Park, Wildcat Creek, 400’ asl, 22 September 1990, D. Ubick, f. Trinity Co: 10 mi west of Castella, 5,500’ asl, 28 March 1969, T. Briggs, Ƌ ♀; Forest Glen Cave, 20 October 1999, D. Ubick, ♀; Burnt Ranch, N40°23.63’, W123°08.96’, 9 July 1946, S. Mulaik, juvs. ( AMNH).

The distributions of T. ubicki   and T. pallipes   are incompletely known, especially in northern California, where most samples of Taracus   are of juvenile specimens. At least for the tier of California counties bordering Oregon, these juvenile specimens could represent pallipes   . Including the records of juveniles above is based on our judgment of the similarity of the specimens to ubicki   ; there are many more about which we could not decide. Mature material from Sonoma, Marin, Mendocino and Trinity Counties   ties the distribution together, but obviously field work is needed in northern California to clarify the distributions of ubicki   and pallipes   , if the latter does in fact occur in California.

Notes. Records are sparse but it appears that ubicki   , like pallipes   , is a winter-maturing species, though adults occur as early as September. All records of juveniles are from June to September. That suggests that any collecting to determine the limits of the distribution of the two species should be carried out no earlier than September. In Siskiyou Co., ubicki   and fluvipileus   are potentially sympatric, but there is no chance of confusing the two, given the long, thin chelicerae of fluvipileus   .

MAP 7. Northern California. Filled circles, Taracus audisioae   , n. sp.; filled triangles, T. ubicki   , n. sp.

MAP 8. Northern California and western Washington and Oregon. Filled circles, localities for Oskoron spinosus (Banks)   ; filled triangles, localities for O. brevipalpis   , n. sp.; filled squares, localities for O. crawfordi   , n. sp.  

TABLE 20. Lengths in mm of palpal and leg articles of male Taracus ubicki.

    Patella Tibia    

TABLE 21. Lengths in mm of palpal and leg articles of female Taracus ubicki.

    Patella Tibia    

California Academy of Sciences


American Museum of Natural History