Taracus carmanah 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 : 34-36

Taracus carmanah Shear , new species

Figs. 45–52 , Map 2

Types. Male holotype and male paratype (CNC) from upper Carmanah Valley, Carmanah Walbran Provincial Park (N48°39’00”, W124°39’00”) Vancouver Island, British Columbia, Canada, collected 17 to 26 October 1991 by N. Winchester. Additional male paratype (CNC) from Carmanah Creek, Vancouver Island, British Columbia, Canada, collected 5–20 November 1997, collector unknown.

Diagnosis. Taracus carmanah resembles T. pallipes or T. gertschi in general appearance, but is somewhat smaller-bodied, with longer legs in proportion to the body length and shorter (and smoother) chelicerae. Males of pallipes and gertschi show scutum parvum, but males of carmanah do not have a scutum, instead displaying regularly-arranged, large, seta-bearing plaques on the abdominal dorsum, which is strongly pigmented. Comparison with silvestrii is difficult, since that species is known only from females, but silvestrii males probably have shorter legs compared to body length.

Etymology. The species name refers to the type locality and is a noun in apposition.

Description. Male holotype. Total length, 4.20 mm. Carapace medium brown, merging at lateral margins into white, membranous cuticle; anterior, posterior, anteriolateral borders well-defined; central region strongly domed; midline sulcus extends from anterior margin to ocularium; “hash marks” on either side of ocularium absent. Ocularium high, about as long as wide, rounded, with three small, seta-bearing tubercles above each eye; eyes large, black, ringed with black pigment. Metapelitidium long, not sclerotized, without seta; sensory cone unusually long, seen laterally, higher than ocularium, white at base, tipped brown, acute, set in shallow embayment in posterior edge of carapace. Abdomen soft, yellowish white, each segment demarcated by paired areas of purplish gray pigment, with sclerotized seta-bearing plaques regularly arranged as shown in Figs. 49 and 50 . Ventrally, coxae tan, unspotted. Palpal coxae with stout setae on small but distinct tubercles, Leg coxae with black setae not on tubercles. No indication of thoracic sternum. Genital operculum apically rounded, heavily setose, light brown, unspotted, paired spots of dark pigment at base. Abdominal sternites not sclerotized, yellowish white, indicated by sparse rows of small, black setae.

Chelicerae ( Figs. 51, 52 ) 7.05 mm long, black. Basal article 3.05 mm long, 0.43 mm wide (L/W = 7.09); second article 4.00 mm long, 0.63 mm wide (L/W = 6.35). Basal article with mediobasal knob somewhat elongate, in mesal view with few small seta-tipped tubercles, distally and laterally nearly smooth; second article with slightly more prominent, low, rounded seta-tipped tubercles ranged in about five 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.46 ) pale, distally shaded brown, slender, total length 8.96 mm; trochanter with four low, seta-tipped tubercles. Lengths of articles as given in Table 8 . Legs short relative to body length, medium brown, unspotted. Autospasy sutures of femora distinct on all legs. Tibiae without false articulations, all metatarsi with false articulations, numbering 10, 22, 9, 15 respectively. Total lengths in mm of legs 1–4: 19.22, 28.00, 16.61, 23.89. Measurements of leg articles given in Table 8 .

Penis ( Figs.47, 48 ) 1.92 mm long, 0.30 mm wide, L/W = 6.4, tapering evenly to glans; glans heavily setose, aculeus spirally twisted; shaft below glans with many scattered setae.

Females unknown.

Distribution. Known only from the type localities on southwestern Vancouver Island. An early instar juvenile specimen taken not far from there in Hourglass Cave, Gordon River (N48°46’, W124°23’) by Patrick Shaw, 21 September 1997 (CNC), may well be T. carmanah . This species should be searched for in similar habitats on the Olympic Peninsula, Washington, USA.

Notes. The type locality, Carmanah Walbran Provincial Park, is a primitive wilderness area of over 16,000 ha preserving primary old-growth coastal forests, including Canada’s largest trees. The upper Carmanah Valley lies in the Submontane Very Wet Maritime subzone of the Coastal Western Hemlock biogeoclimatic zone, characterized by year-round mild temperatures and heavy rainfall, with a brief drier season in summer (British Columbia Ministry of Environment 2010).

The very long legs of T. carmanah rival those of the troglobiont, T. marchingtoni . The available specimens somewhat resemble certain sclerosomatids in their proportions, due to the long legs and small bodies.

Figures

FIGURES 37 – 45. Taracus gertschi. Fig. 37, female palpus. Fig. 38, male palpus. Fig. 39, penis. Fig. 40, glans penis. Fig. 41, female, dorsal view. Fig. 42, female, lateral view. Fig. 43, female chelicerae, lateral view. Fig. 44, female chelicera, second article, frontal view. Fig. 45, male chelicera, lateral view.

FIGURES 46 – 52. Taracus carmanah male. Fig. 46, palpus. Fig. 47, penis. Fig. 48, glans penis. Fig. 49, dorsal view. Fig. 50, lateral view. Fig. 51, chelicera, lateral view. Fig. 52, chelicera, second article, frontal view.

Tables

TABLE 8. Lengths in mm of palpal and leg articles of male Taracus carmanah.

	Femur	Patella	Tibia	Metatarsus	Tarsus
Palpus	3.33	2.46	2.30	-	0.87
Leg 1	4.92	1.00	3.30	6.00	4.00
Leg 2	6.85	1.54	5.92	7.69	6.00
Leg 3	3.92	1.00	3.00	5.00	3.69
Leg 4	6.30	1.23	3.76	6.92	5.69