Gymnobisium cuneatum, Neethling & Neethling, 2023

Neethling, J. A. & Neethling, C., 2023, A systematic revision of the South African Gymnobisiidae (Pseudoscorpiones: Neobisioidea), Zootaxa 5256 (6), pp. 501-543 : 512-516

Gymnobisium cuneatum sp. nov.

Figs 8–10

Holotype: ♀, SOUTH AFRICA, Eastern Cape, Hogsback, Hogsback State Forest, 32°36′S, 26°56′E, 1080m a.s.l., Afromontane forest , Leaf litter sifting, leg. J.A. Neethling, 20.III.2013 ( NMBAP 00339 ).

Paratype: ♂, Same data as holotype ( NMBAP 00342 ) .

Etymology. The Latin adjective cuneatum means wedge-shaped. The name refers to the shape of the chela that is characteristic for this species.

Diagnosis. Moderately sized species (chela length ♀ 1.28–1.30 mm, ♂ 1.20 –1.23 mm) with short, robust chelal fingers giving the chelae a wedge shape; female chelae not significantly more bulbous than male’s (chela ratio ♀ 3.12–3.17 versus ♂ 3.24 –3.32 times longer than broad); fixed finger multi-toothed structure with five strongly sclerotized teeth; cheliceral hand with five setae; galea with six rami; rallum with eight blades. Differs from all congeners by the wedge-shaped appearance of their chelae.

Description

Carapace: Somewhat longer than broad, subquadrate, overall smooth and without furrow. Brown in females, dark brown in males. Two pairs of eyes located dorso-laterally at the front ( Fig. 8A, C ). Small seta located on the dorso-anterior margin of each of the posterior eyes. Carapace with 22 setae in both sexes, arranged 4: 6: 4: 2: 6.

Abdomen: Tergites and sternites smooth, undivided and uniseriate. Female abdominal tergites uniformly brown, slightly lighter than carapace. Male tergites same colour as carapace and uniform ( Fig. 8A, C ). In both sexes the lateral and posterior edges of tergites I–XI are slightly lighter in colour, tergite XII uniformly lighter in colour. The tergal setae are located on the posterior edge of each tergite. Sternal colouration differs between male and female ( Fig. 8B, D ). In females the sternites darken from tan near the coxae to light brown at the posterior of the abdomen. Male sternites stay tan with marginally darker lateral edges from sternites I–VIII, then dark brown for sternites IX–XI. Tergite and sternites XII light brown in colour in both sexes. Sternites I and II are fused and hardly distinguishable. Female operculum with eight setae clustered in two groups along the posterior border of sternite II, one group at each side of the genital opening. Males with 16 setae at the operculum cluster on the posterior edge of sternites II, 13 setae on the anterior edge of sternite III at the genital opening. Pleural membrane cream to light yellow in colour, faintly papillate.

Tergal chaetotaxy: 6(6): 7(7): 10(9): 12(10): 12(12): 12(12): 11(12): 11(11): 10(8): 8(8): 9(11): 2(2).

Sternal chaetotaxy: 8(16):?(?): 23(19): 18(19): 14(17): 16(15): 14(15): 14(15): 15(14): 12(13): 9(11): 2(2).

Pedipalp: All segments smooth and brown in colour in both sexes. Trochanter cone-shaped and rounded anteriorly, curved slightly posteriorly. Base narrow, widening distally. Setae present on the anterior surface. Femur slender, 3.50–3.70 (♀) to 3.55–3.72 (♂) times longer than wide, somewhat constricted basally, widening just distal of base. Shallow disto-prolateral excavation present. Setae absent from base, though distributed evenly over rest of surface. Patella constricted and slightly angled at base, widening markedly distal at just under a third segment length, 2.37–2.48 (♀) to 2.46–2.54 (♂) times longer than wide. Several small lyriform fissures present on the dorsal surface, just distal of base. Two larger lyriform fissures present latero-dorsally from these, where the segment starts to widen. Shallow disto-prolateral excavation present. Setae sparse at base, more numerous on wide part of patella ( Fig. 10B ).

Chela: In both sexes smooth and uniformly brown, fingers may be slightly darker. Both male and female chela similarly wedge-shaped, convex on the prolateral edge, less so on the retrolateral edge. Male hand smaller. Pedicel regular in both sexes, retrolateral condyle very small and rounded. Fingers thick, much shorter than hand (without pedicel) and curved slightly prolaterally ( Fig. 9A–D ). Fixed and movable chelal fingers with eight and four trichobothria respectively ( Fig. 10A ).

Terminal multi-toothed structure of fixed finger small and extends beyond venom tooth of movable finger in both sexes. In both sexes ( Fig. 10D ), consists of a large terminal tooth preceded by four smaller, heavily sclerotized, teeth that do not extend lower than the terminal tooth. Both fingers with rounded, juxtadentate teeth situated on flexible lamellae. Lamella on fixed finger originating roughly one third finger length from base, on movable approximately in the middle. Female fixed finger with 38–39 lightly sclerotized, juxtadentate teeth, 11 proximal to lamella base, together with five strongly sclerotized teeth on distal structure. Male fixed finger with 39–40 lightly sclerotized, juxtadentate teeth, 10–11 proximal to lamella base, together with five strongly sclerotized teeth on distal structure. Female movable finger with 33–34 lightly sclerotized, juxtadentate teeth, 12–13 proximal to lamella base. Male movable finger with 32–35 lightly sclerotized, juxtadentate teeth, 12–14 proximal to lamella base. Two thickened, spine-like setae present on distal end of movable finger in both sexes.

Chelicera: Hand with five long and acuminate setae, es shorter ( Fig. 10C ). Both male and female fixed finger with 13 teeth, moveable finger of both with eight teeth. Galea of both sexes divided into two major rami, each terminating in three smaller rami ( Fig. 10E ). Male and female rallum with eight ( Fig. 10F ) long, acuminate blades. Lamina exterior absent in both sexes.

Coxae and legs: Pedipalpal coxae same colour, or slightly lighter than rest of pedipalps. Coxae I–IV tan. Legs I–IV light brown to tan in colour. All legs diplotarsate with subterminal tarsal setae dentate distally; claws simple; arolium shorter than claws.

Measurements (mm): Body length ♀ 2.12– 2.30 ♂ 1.79–1.89; Carapace ♀ 0.56–0.59 x 0.63–0.68 (0.87–0.89) ♂ 0.55 –0.58 x 0.58–0.60 (0.95–0.97); Chelicera ♀ 0.48–0.49 x 0.25–0.26 (1.88–1.92) ♂ 0.44 –0.45 x 0.23–0.24 (1.87–1.91), movable finger length ♀ 0.28– 0.29 ♂ 0.26; Pedipalps: femur ♀ 0.74–0.77 x 0.20–0.22 (3.50–3.70) ♂ 0.67 –0.71 x 0.18–0.20 (3.55–3.72), patella ♀ 0.64–0.67 x 0.27 (2.37–2.48) ♂ 0.61 –0.64 x 0.24–0.26 (2.46–2.54), chela ♀ 1.28–1.30 x 0.41 (3.12–3.17) ♂ 1.20 –1.23 x 0.37 (3.24–3.32), hand ♀ 0.70–0.73 x 0.41 (1.71–1.78) ♂ 0.65 –0.68 x 0.37 (1.76–1.84), movable finger length ♀ 0.50– 0.52 ♂ 0.47–0.49; Leg I: femur ♀ 0.34–0.38 x 0.10 (3.40–3.80) ♂ 0.35 x 0.08–0.09 (3.89–4.37), patella ♀ 0.22–0.25 x 0.10 (2.20–2.50) ♂ 0.23 –0.25 x 0.09 (2.55–2.78), tibia ♀ 0.31 x 0.09 (3.44) ♂ 0.27 –0.29 x 0.09 (3.00–3.22), metatarsus ♀ 0.14–0.15 x 0.07 (2.00–2.14) ♂ 0.14 –0.15 x 0.07 (2.00–2.14), tarsus ♀ 0.22–0.23 x 0.06 (3.67–3.83) ♂ 0.20 –0.22 x 0.06 (3.33–3.67); Leg IV femoropatella ♀ 0.69–0.76 x 0.18–0.19 (3.83–4.00) ♂ 0.73 x 0.22 (3.32), tibia ♀ 0.58–0.60 x 0.12 (4.83–5.00) ♂ 0.51 –0.57 x 0.12 (4.25–4.75), metatarsus ♀ 0.24 x 0.08–0.09 (2.67–3.00) ♂ 0.24 x 0.08 (3.00), tarsus ♀ 0.30–0.32 x 0.08 (3.75–4.00) ♂ 0.29 –0.30 x 0.08 (3.62–3.75).

Remarks. The species is known only from its type locality.

Additional material examined. SOUTH AFRICA: Eastern Cape: 2♀, 4♂, Hogsback, Hogsback State Forest, 32°36′S, 26°56′E, 1080m a.s.l., Afromontane forest , Leaf litter sifting, leg. J.A. Neethling, 20.III.2013 ( NMBAP 00328 ) .

Figures

FIGURE 8. Digital microscope photographs of Gymnobisium cuneatum sp. nov., Female (A, B) and Male (C, D). A, C. Dorsal view; B, D. Ventral view. Scale bar: 1.00 mm.

FIGURE 9. Digital microscope photographs of Gymnobisium cuneatum sp. nov. right chela: Female (A, B) and Male (C, D). A, C. Retrolateral view; B, D. Dorsal view. Scale bar: 1.00 mm.

FIGURE 10. Gymnobisium cuneatum sp. nov. A. Female right chela, retrolateral view; B. Female right pedipalp, dorsal view; C. Female left chelicera, dorsal view; D. Female chelal fingers, anterior retrolateral view; E. Galea; F. Rallum. Scale bars:A, B: 0.50 mm; C, D: 0.20 mm; E, F: 0.10 mm.