Parobisium yuantongi, Feng & Wynne & Zhang, 2019

Feng, Zegang, Wynne, J. Judson & Zhang, Feng, 2019, Two new subterranean-adapted pseudoscorpions (Pseudoscorpiones: Neobisiidae: Parobisium) from Beijing, China, Zootaxa 4661 (1), pp. 145-160 : 152-156

Parobisium yuantongi sp. n.

( Figs 6–8 )

Type material. Holotype male (Ps.- MHBU-BJ 18061010 ): China, Beijing City, Fangshan District, Shijiaying Town , Shenxian cave , [39.867793°N, 115.704571°E], estimated cave deep zone, 603 m elevation, 10 June 2018, Zegang Feng leg.

Diagnosis. Troglomorphic habitus; carapace without eyes or eyespots; epistome triangular, with rounded top; carapace with 6 setae on posterior margin; pedipalp slender and with granulation present on femur, inside lateral of patella and chelal hand, both chelal fingers with 115–118 teeth; femur 6.75 times (length 1.62), patella 5.70 times (length 1.54) longer than broad, pedicel about half of total length of patella. Hand with pedicel 3.00 times (length 1.05), chela with pedicel 8.00 times (length 2.80) longer than broad, finger 1.69 times longer than hand with pedicel. Chelicera: rallum with 8 pinnate setae, distal one with an expanded base.

Description. Male ( Fig. 6 ). Carapace, chelicerae and pedipalps light yellow brown; abdomen and legs yellow- ish.

Carapace ( Figs 7A , 8A ): Smooth, 1.46 times longer than broad, with a total of 22 setae, including 4 on anterior margin and 6 on posterior margin; lacks eyes or eyespots; epistome small, triangular, with rounded top.

Chelicera ( Figs 7B , 8B ): Hand with 6 setae, movable finger with one submedial seta; fixed finger with 14 teeth; movable finger with 11 teeth; serrula exterior with 24–26 lamellae; serrula interior with 26–28 lamellae. Galea ( Fig. 8D ) replaced by a small rounded transparent spinneret. Rallum ( Fig. 8C ) with 8 pinnate setae, distal one separated and with expanded base, proximal one short.

Pedipalps ( Figs 7 C–D, 8G–H): Apex of coxa rounded, with 4–5 setae on each side. Pedipalp slender and with granulation present on femur, inside lateral of patella and chelal hand. Trochanter 3.33, femur 6.75, patella 5.70, chela (with pedicel) 8.00, chela (without pedicel) 7.37 times longer than wide, movable finger 2.19 times longer than hand (without pedicel). Fixed chelal finger with 8 trichobothria, movable finger with 4, eb and esb on lateral margin of hand; ib, ist, and isb closely grouped at the base of the fixed finger; est situated at the subdistal of finger; est, et and it grouped together near fingertip; b situated at base of movable finger, sb situated at one-third base of the finger, st and t at one-third distal of movable finger, st nearer to t than to sb, the latter distinctly nearer to b than to st, the distance between b and sb longer than that between t and st. Venom apparatus present only in fixed chelal finger, venom duct short. Fixed chelal finger with 116 teeth, movable finger with 118 teeth.

Abdomen: Pleural membrane granulated. Tergal chaetotaxy (I–XI): 6: 9: 11: 11: 11: 12: 11: 11: 11: 10: 7; sternal chaetotaxy (IV–XI): 16: 14: 14: 13: 14: 12: 11: 3; stigmata with 3–5 setae around; anal cone with 2 dorsal and 2 ventral setae. Male genital area ( Fig. 8F ): sternite III with 11 setae on the posterior margin; with 6 setae around the anteromedian groove; sternite III with a row of 11 setae on the posterior margin.

Legs: Leg I ( Figs 7E , 8I ) and Leg IV ( Figs 7F , 8J ) typical. Tibia IV with one submedial tactile seta (TS = 0.50), basitarsus IV with one basal tactile seta (TS = 0.11), telotarsus IV with one tactile seta (TS = 0.51). Subterminal tarsal seta ( Fig. 8E ) bifurcate; arolium not divided, shorter than the slender and simple claws.

Measurements: (length/breadth or depth in mm; ratios for most characters in parentheses). Male. Body length 2.98. Carapace 1.46 (1.04/0.71). Pedipalpal trochanter 3.33 (0.80/0.24), femur 6.75 (1.62/0.24), patella 5.70 (1.54/0.27), chela (with pedicel) 8.00 (2.80/0.35), chela (without pedicel) 7.37 (2.58/0.35), hand length (without pedicel) 0.81, movable finger length 1.77 (2.19 times longer than hand without pedicel). Leg I: trochanter 1.42 (0.27/0.19), femur 5.80 (0.87/0.15), patella 4.15 (0.75/0.10), tibia 7.50 (0.75/0.10), basitarsus 5.00 (0.40/0.08), telotarsus 6.86 (0.48/0.07). Leg IV: trochanter 2.67 (0.46/0.18), femur + patella 5.07 (1.37/0.27), tibia 8.60 (1.29/0.15), basitarsus 4.00 (0.44/0.11), telotarsus 6.78 (0.61/0.09).

Distribution. This species is known only from the type locality.

Etymology. The species name, yuantongi , was derived from the Latinized Mandarin phrase for “shaped like a cylinder” or “cylindrical.” Yuán tǒng (Oifi) refers to the shape of chelal hand.

Remarks. The new species resembles P. longipalpus Hong, 1996 but is distinguished by the lack of eyes or eyespots ( P. longipalpus has four conspicuous eyes), the slender pedipalpal femur 6.75 longer than broad (3.6–4.9 times in P. longipalpus , patella 5.70 times longer than broad (2.9–3.3 times in P. longipalpus ).

P. yuantongi sp. n. also resembles P. robustiellum Hong, 1996 , but it can be differentiated from the latter by lack of eyes or eyespots ( P. robustiellum has four eyes), chelal fingers with 115–118 teeth (about 51–66 teeth in P. robustiellum ); the slender pedipalpal femur 6.75 longer than broad (2.5–3.6 times in P. robustiellum ), patella 5.70 times longer than broad (2.7–3.4 times in P. robustiellum ).

P. yuantongi sp. n. can be easily distinguished from P. anagamidense ( Morikawa, 1957) by the following characters: carapace without eyes/eyespots ( P. anagamidense ( Morikawa, 1957) , epistome triangular, with rounded top (absent in P. anagamidense ); pedipalpal femur 6.75 longer than broad (4.0–4.2 times in P. anagamidense ( Morikawa, 1957) patella 5.70 longer than broad (2.9 times in P. anagamidense ( Morikawa, 1957) .

P. yuantongi sp. n. differs from P. magangensis sp. n. by the pedipalpal morphology and size: pedipalp with granulation present on femur, inside lateral of patella and chelal hand (smooth in P. magangensis sp. n.), pedipalpal femur 6.75 longer than broad (8.91–8.97 times in P. magangensis sp. n.), patella 5.70 longer than broad (7.64–7.84 times in P. magangensis sp. n.).

Figures

FIGURE 6. Parobisium yuantongi sp. n. Holotype male, dorsal view.

FIGURE 7. Parobisium yuantongi sp. n., holotype male: A. Carapace (dorsal view); B. Right chelicerae (dorsal view); C. Left chela (lateral view); D. Left pedipalp (dorsal view); E. Right leg I (lateral view); F. Right leg IV (lateral view).

FIGURE 8. Parobisium yuantongi sp. n., holotype male. A. Carapace, dorsal view; B. Right chelicera, dorsal view; C. Rallum; D. Movable finger of chelicerae, showing galea; E. Subterminal tarsal seta; F. Genital area of male; G. Right chelal, lateral view; H. Right pedipalp, dorsal view (trochanter, femur and patella); I. Right leg I, lateral view; J. Right leg IV, lateral view. Scale bars: 0.1 mm (F, G), 0.25 mm (I), 0.5 mm (B, D, E), 1 mm (A, H, J).