Homolophus arcticus Banks, 1893

Snegovaya, Nataly Yu. & Cokendolpher, James C., 2021, Further studies on harvestman genus Homolophus (Opiliones: Phalangiidae), with descriptions of two new species, Zootaxa 4908 (3), pp. 301-353 : 319-321

Homolophus arcticus Banks, 1893

Figures 10–11

Homolophus arcticus Banks, 1893: 208 ; Staręga 1978: 209; Cokendolpher 1987: 91; Tsurusaki 1987: 97–102, figs. 1–5; Li & Song 1993: 239; Crawford (1996 web page); Zhu et al. 1999: 7–8, fig. 1; Tchemeris 2000: 35–36, figs. 12–16; Tsurusaki & Song 2000: 162, fig. 5; Staręga 2003: 96

Opilio sachaliensis Suzuki, 1941: 245–247 , figs. 8–13; Suzuki 1956: 97–100, figs. 1–7 [junior subjective synonym of Phalangium nordeskiöldi var. albofasciatum Kulczyński, 1901 by Staręga (1964); removed to synonymy of Egaenus zichyi Kulczyński 1901 by Staręga (1978); synonymies rejected and considered as junior subjective synonym of Homolophus arcticus Banks, 1893 by Tsurusaki (1987)].

Opilio sunuitensis Nakatsudi, 1943: 108–109 , fig. 2

Opilio sachalinus Roewer, 1956: 277 , 295, pl. 41, figs. 153–155 [junior subjective synonym of Phalangium nordeskiöldi var. albofasciatum Kulczyński, 1901 by Staręga (1964); removed to synonymy of Egaenus zichyi Kulczyński 1901 by Staręga (1978); synonymies rejected and considered as junior subjective synonym of Homolophus arcticus Banks, 1893 by Cokendolpher (1987)].

Opilio kurilus Roewer, 1956: 279 , 280–289, pl. 40, figs. 131–133 [junior subjective synonym of Phalangium nordeskiöldi var. albofasciatum Kulczyński, 1901 by Staręga (1964); removed to synonymy of Egaenus zichyi Kulczyński 1901 by Staręga (1978); synonymies rejected and considered as junior subjective synonym of Homolophus arcticus Banks, 1893 by Tsurusaki (1987)].

Opilio nipponensis Roewer, 1956: 279 , 292–293, pl. 40, figs. 139–141 [junior subjective synonym of Homolophus arcticus Banks, 1893 by Staręga (2003)]

Euphalangium albofasciatum — Staręga 1964: 399

Egaenus zichyi — Staręga 1978: 222

Diagnosis. The species differs from all congeners, including the most closely related, H. chemerisi (Staręga & Snegovaya, 2008) and H. tibetanus ( Roewer, 1911) , by the following: cephalothorax with group of fairly large darklycolored-tipped denticles in center on anterior edge; short legs, I and III pairs thickened; penis glans thickened, with somewhat squared-off tip (lateral view) and oval (dorsal view); shape of truncus (wide at base gradually getting thinner to about distal third which stays slender to end).

Type Locality. Russia, Kamchatka Oblast, Komandorskiye Ostrova- “Commander Island, Siberia”, ca. 55°12’0”N, 165°59’24”E .

Distribution. China: Gansu, Xinjiang, Sichuan. Russia (Kamchatka Oblast and Sakhalin Oblast), Japan (Hokkaido), North Korea, and here newly recorded from Mongolia ( Fig. 11 ).

Specimens Examined. RUSSIA, Khabarovsk Territory, Bureinsky Reserve , birch-wood, 12– 17.08.2002, leg. L. Triliskauskas (1 male, 1 female, RCNS) . MONGOLIA, 1899, leg. A. Soldatov, field # N151-1899 (1 male, 1 female, ZIN) ; Tov Aimak, 40 km ESE of Ulanbator , 47°48.88’N, 107°26.22’E, 1500 m a.s.l., 28– 30.07.2003, leg. O. Gorbunov (1 male, 4 females, 12 juv., RCNS) . JAPAN, Wakasakanai, Toyotomi-chô, Teshio-gun , Hokkaido, 06.08.1985, leg. N. Tsurusaki (specimen already recorded by Tsurusaki, 1987) (1 male, AMNH) .

Description. Medium-sized harvestmen; male body rectangular, with rounded corners; medium sclerotization of body cuticle, less slender, 1.8 times longer than wide; length 6.5 mm, width 3.5 mm; with small hardly noticeable denticles along borders of tergites; cephalothorax darker and dark spots on abdomen arranged transversely along centers of tergites. Entire body length with central incomplete line of light color; Ocularium low, round to slightly wider than long, small, 1.9 times its length from anterior margin of cephalothorax, with 4 denticles on each side. Anterior edge of cephalothorax with group of fairly large darkly colored-tipped denticles; many smaller denticles in front of and lateral sides of area around ocularium. Legs short, angular in cross-section, I and III pairs thickened, especially Fe; Fe all legs with longitudinal rows of denticles. Leg lengths (mm): I 2.8 + 1.5 + 2.7 + 2.5 + 5.1 = 14.6, II 4.2 + 1.5 + 4.3 + 3.7 + 11.5 = 25.2, III 2.2 + 1.3 + 2.8 + 3.3 + 6.3 = 15.9, IV 4.2 + 1.4 + 3.2 + 4.8 + 9.0 = 22.6. Pedipalp segment lengths (mm): 1.5 + 0.8 + 1.0 + 1.5 = 4.8. Pedipalps thickened (sexually dimorphic), Fe ventrally and dorsally with denticles, Pa dorsally and laterally, Ti ventrally densely covered with denticles, dorsally and laterally are not densely covered, Ta ventrally covered by strip of sensory microdenticles on basal half. Chelicerae enlarged (sexually dimorphic) with some tabby marks, basal segment dorsally with several denticles, distal segment dorsally with few microdenticles. Cheliceral basal segment ventrally with blunt rounded bulge, length 2.0 mm, distal segment length 2.5 mm. Penis short, dorsoventrally flattened, bowed, recurved in lateral view, length (mm): truncus 2.9, glans 0.5, stylus 0.15; wide at base, gradually thinning on basal half of truncus, distal end uniform width extending to glans, glans oval in shape.

Female differs from male in larger size, presence of densely placed denticles (few sharing same enlarged base) on anterior part of cephalothorax, in front of ocularium. Body rectangular, with rounded corners; less slender, 2.21 times longer than wide; body length 6.2 mm, width 2.8 mm. Leg lengths (mm): I 2.3 + 1.0 + 2.0 + 2.3 + 5.0 = 12.6, II 4.0 + 1.2 + 3.3 + 3.0 + 8.5 = 20.0, III 2.3 + 1.0 + 2.0 + 2.8 + 5.3 = 13.4, IV 3.5 + 1.3 + 2.7 + 4.3 + 7.6 = 19.4. Pedipalp segment lengths (mm): 1.0 + 0.5 + 0.8 + 1.3 = 3.6. Cheliceral basal segment length 1.4 mm, distal segment length 1.5 mm.

Comments. The male studied from Japan differs slightly from illustrations herein by having the distal end of glans more truncated. Truncus of penis of Japanese specimen is very dorsoventrally flattened near middle and lower 1/2 of truncus and then more rounded in distal 1/4 end (see Tsurusaki 1987: fig. 4B).

Figures

FIGURE 10. Homolophus arcticus Banks, 1893: A, male body, dorsal; B, male ocularium, dorsal; C, female body, dorsal; D, female ocularium, dorsal; E, male femur I, dorsal; F, male right pedipalp, mesal; G, male right pedipalp, ectal; H, male right che- licera, mesal; I, male right chelicera, ectal; J, female right pedipalp, mesal; K, female right pedipalp, ectal; L, female right che- licera, mesal; M, female right chelicera, ectal; N, penis, dorsal; O, penis, lateral; P, penis glans, dorsal; Q, penis glans, lateral.

FIGURE 11. Distribution of some Homolophus species in the Palearctic: Central and East Asia. Data for pale colored symbols (red without black dot) taken from literature; identifications not verified.