Gymnobisium octoflagellatum Beier, 1947

Neethling, J. A. & Neethling, C., 2023, A systematic revision of the South African Gymnobisiidae (Pseudoscorpiones: Neobisioidea), Zootaxa 5256 (6), pp. 501-543 : 524-529

Gymnobisium octoflagellatum Beier, 1947

Figs 18–20

Gymnobisium octoflagellatum Beier, 1947: 291–292 , fig. 4; Vitali-di Castri, 1970: 126; Harvey, 1991: 312; Dippenaar-Schoeman & Harvey, 2000: 92; Harvey et al. 2016: 76.

Holotype: 1 Adult, SOUTH AFRICA, Western Cape, Grabouw, Viljoen’s Pass [34°4′S, 19°4′E], leg. R.F. Lawrance ( SAMC B8509 ), examined.

Epitype: ♀, SOUTH AFRICA, Western Cape, Grabouw, Viljoen’s Pass, Hottentots Holland Nature Reserve , 33°4′S, 19°3′E, 587m a.s.l., Mountain Fynbos , Leaf litter sifting, leg. J.A. Neethling & C. Neethling, 4.IV.2016 ( NMBAP 00338 ) .

Diagnosis. Moderately sized species (chela length ♀ 1.56–1.65 mm, ♂ 1.39 –1.42 mm), with chelae significantly more bulbous in females than in males (chela ratio ♀ 3.25–3.30 versus ♂ 4.06 –4.21 times longer than broad); fixed finger multi-toothed structure with eight strongly sclerotized teeth; cheliceral hand with five setae; galea with eight to ten rami; rallum with eight to nine blades. Differs from all congeners by having a minimum of eight rami on the galea versus a maximum of seven in all other species.

Description

Carapace: Somewhat broader than long, subquadrate, overall smooth and without furrow. Very dark brown in females, appearing almost black, lighter in males. Two pairs of eyes located dorso-laterally at the front ( Fig. 18A, C ). Small seta located on the dorso-anterior margin of each of the posterior eyes. Female carapace with 20 setae, arranged 4: 4: 4: 2: 6. Male carapace possess mostly the same chaetotaxy as female, though some specimens varied by having 18 setae, arranged 4: 3: 4: 2: 5.

Abdomen: Tergites and sternites smooth, undivided and uniseriate. Female abdominal tergites same colour as carapace. Male tergites same colour as carapace. Lateral and posterior edges of tergites I–XI lighter in colour, more so in males, tergite XII uniformly lighter in colour. The tergal setae are located on the posterior edge of each tergite, within the lighter coloured band. Female sternites mostly same colour as tergites, slightly lighter, and strongly sclerotized. Female genital operculum tan to light brown in colour. Male sternites I–II tan; III–VIII light brown, becoming slightly darker to posterior of abdomen; IX–XI dark brown. Tergite and sternite XII brown ( Fig. 18B, D ). Sternites I and II are fused and hardly distinguishable. Female operculum with 11 setae, nine loosely clustered in two groups centrally at the posterior edge of sternite II, single seta situated lateral from each group, at the posterior margin of sternite. Males with 21 setae at the operculum cluster on sternite II, seven along the posterior margin of the sternite at the genital opening, and an additional 14 clustered loosely just anterior of these, centrally on sternite II. Male sternite III with 10 setae situated along the anterior margin, at the genital opening. Pleural membrane cream to light yellow in colour, faintly papillate.

Tergal chaetotaxy: 6(6): 8(8): 10(9): 12(9): 12(11): 12(11): 11(11): 10(10): 10(11): 9(9): 13(9): 2(2).

Sternal chaetotaxy: 11(21):?(?): 18(24): 17(15): 15(14): 15(17): 17(15): 15(15): 12(15): 12(11): 13(9): 2(2).

Pedipalp: All segments smooth, orange-brown in females, slightly lighter in males. Trochanter cone-shaped and rounded anteriorly, curved slightly posteriorly. Base narrow, widening distally. Setae present on the anterior surface. Femur slender, 3.71–3.83 (♀) to 4.05–4.10 (♂) times longer than wide, somewhat constricted basally, widening just distal of base. Deep 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 around a third segment length, 2.63–2.71 (♀) to 2.92–3.00 (♂) 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. 20B ).

Chela: In both sexes smooth and uniformly orange-brown, slightly lighter in males. Female hand larger and markedly more bulbous, strongly convex on the prolateral edge, slightly less so on the retrolateral edge ( Fig. 19A, B ). Male hand smaller, markedly less convex prolaterally ( Fig. 19C, D ). Pedicel as long as wide in females, slightly longer than wide in males. Retrolateral condyle small but distinct and rounded in both sexes. Fingers narrow, same length as hand (without pedicel) to slightly longer than hand (without pedicel) in females. Male chelal fingers narrow and slightly shorter in length than hand (with pedicel). Fingers curved slightly prolaterally in both sexes. Fixed and movable chelal fingers with eight and four trichobothria respectively ( Fig. 20A ).

Terminal multi-toothed structure extends well beyond venom tooth of movable finger in both sexes, curving downward. Female structure slightly more curved than male. In both sexes the structure consists of a large terminal tooth preceded by a row of six smaller, highly sclerotized teeth that reduce in size away from the terminal tooth. This row is situated slightly prolaterally behind the terminal tooth. Located retrolaterally at the base of the smaller teeth is another larger tooth ( Fig. 20D ). Both fingers with rounded, juxtadentate teeth situated on flexible lamellae. Lamella on female fixed finger originating roughly one fifth finger length from base, originating between sb and st on movable finger. Lamella on male fixed finger originating slightly less than one third finger length from base, originating between sb and st on movable finger. Female fixed finger with 50–52 lightly sclerotized, juxtadentate teeth, 10–11 proximal to lamella base, together with eight strongly sclerotized teeth on distal structure. Male fixed finger with 50–52 lightly sclerotized, juxtadentate teeth, 11–12 proximal to lamella base, together with eight strongly sclerotized teeth on distal structure. Female movable finger with 41–43 lightly sclerotized, juxtadentate teeth, nine proximal to lamella base, 31–33 on lamella, and one small, lightly sclerotized tooth at the posterior base of the venom tooth. Male movable finger with 45–49 lightly sclerotized, juxtadentate teeth, 13–14 proximal to lamella base, 31–34 on lamella, and one small, lightly sclerotized tooth at the posterior base of the venom tooth. Two thickened, spine-like seta present on distal end of movable finger in both sexes.

Chelicera: Hand with five long and acuminate setae, es shorter ( Fig. 20C ). Fixed finger with 12 teeth in both sexes. Female moveable finger with eight teeth, male with seven. Female galea divided into two major rami, terminating in three smaller rami on one branch and five on the other ( Fig. 20E ). Male galea divided into two major rami, each terminating in five smaller rami ( Fig. 20F ). Female rallum with eight long, acuminate blades ( Fig 20G ), male rallum with nine blades ( Fig. 20H ). Lamina exterior absent in both sexes.

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

Measurements (mm): Body length ♀ 1.88– 1.99 ♂ 1.78–1.83; Carapace ♀ 0.66–0.68 x 0.69–0.74 (0.92–0.96) ♂ 0.54 –0.57 x 0.60–0.61 (0.90–0.93); Chelicera ♀ 0.51–0.54 x 0.28–0.29 (1.82–1.86) ♂ 0.40 –0.43 x 0.20–0.22 (1.95–2.00), movable finger length ♀ 0.30– 0.32 ♂ 0.24–0.25; Pedipalps: femur ♀ 0.88–0.89 x 0.23–0.24 (3.71– 3.83) ♂ 0.78 –0.81 x 0.19–0.20 (4.05–4.10), patella ♀ 0.76–0.79 x 0.28–0.30 (2.63–2.71) ♂ 0.66 –0.70 x 0.22–0.24 (2.92–3.00), chela ♀ 1.56–1.65 x 0.48–0.50 (3.25–3.30) ♂ 1.39 –1.42 x 0.33–0.35 (4.06–4.21), hand ♀ 0.84–0.89 x 0.48–0.50 (1.75–1.78) ♂ 0.71 –0.73 x 0.33–0.35 (2.08–2.15), movable finger length ♀ 0.75– 0.80 ♂ 0.68–0.69; Leg I: femur ♀ 0.42–0.44 x 0.11–0.12 (3.67–3.82) ♂ 0.36 –0.38 x 0.08 (4.50–4.75), patella ♀ 0.31–0.33 x 0.10–0.11 (3.00–3.10) ♂ 0.28 x 0.09 (3.11), tibia ♀ 0.38–0.39 x 0.08 (4.75–4.87) ♂ 0.31 –0.34 x 0.07 (4.43–4.86), metatarsus ♀ 0.19–0.20 x 0.07 (2.71–2.86) ♂ 0.17 –0.18 x 0.06 (2.83–2.57), tarsus ♀ 0.26–0.27 x 0.06 (4.33–4.50) ♂ 0.22 –0.23 x 0.06 (3.67–3.83); Leg IV femoropatella ♀ 0.80–0.84 x 0.18–0.19 (4.42–4.44) ♂ 0.69 –0.76 x 0.14–0.17 (4.47– 4.93), tibia ♀ 0.71–0.73 x 0.10–0.11 (6.64–7.10) ♂ 0.57 –0.62 x 0.09–0.11 (5.63–6.33), metatarsus ♀ 0.25–0.27 x 0.08 (3.12–3.37) ♂ 0.22 –0.25 x 0.07 (3.14–3.57), tarsus ♀ 0.33–0.36 x 0.07 (4.71–5.14) ♂ 0.29 –0.32 x 0.07 (4.14–4.57).

Remarks. Upon examination of the holotype, we found that the specimen had degraded to such an extent as to be all but unusable. The specimen was broken into parts, the main body separate from the two pedipalps. The trochanter, femur and patella of the left palp were missing. All sclerotized structures had become completely transparent, resulting in the entire body to be light yellow to cream in colour. Delicate structures such as the galea and rallum of the chelicerae were not present and due to the completely clear cuticula, neither the chaetotaxy nor the sex of the specimen could be determined. As such, a new epitype was designated and deposited in the arachnology collection of the National Museum in Bloemfontein. The sex of the holotype was never mentioned in the original description, with the specimen listed merely as “ 1 ad. ”. By comparing the original description to newly collected material, the holotype is most likely a small female specimen.

According to the literature, no additional specimens other than the holotype were ever collected, though three nymphal specimens, housed in the Royal Museum of Central Africa and misidentified as Gymnobisium quadrispinosum , were collected from 1960–1962. No collection date was mentioned for the holotype in the original description, and thus additional adult specimens of the species were then only recollected from the type locality in 2016, at least 69 years after the original holotype.

The chela of Gymnobisium octoflagellatum are nearly identical to those of G. prionotogladiatum sp. nov., in regard to the overall chelal shape, the degree to which female chela differ from those of males, as well as the overall structure, and number of teeth, of the modified terminal tooth on the fixed chelal finger. That said, the species can easily be distinguished by the difference in size, colouration, trichobothrial arrangement, and number of teeth on the chelal fingers.

Additional material examined. SOUTH AFRICA: Western Cape: 2 Nymphs , Cape Town, Table Mountain, Bats Cave [33°58′S, 18°25′E], Leaf litter of Podocarpus trees, leg. N. Leleup, XII.1960 ( RMCA 127850 , previously ZA 43); 1 Clanwilliam [32°20′S, 19°5′E], Leaf litter under large rock, leg. N. Leleup, VII.1962 ( RMCA 127852 , previously ZA 99); 13 Tritonymphs , Grabouw , Viljoen’s Pass , Hottentots Holland Nature Reserve , 33°4′S, 19°3′E, 587m a.s.l., Mountain Fynbos , Leaf litter sifting, leg. J.A. Neethling & C. Neethling, 13.XII.2015 ( NMBAP 00322 ); 6♀, 6♂, 1 Tritonymph, Grabouw, Viljoen’s Pass, Hottentots Holland Nature Reserve , 33°4′S, 19°3′E, 587m a.s.l., Mountain Fynbos , Leaf litter sifting, leg. J.A. Neethling & C. Neethling, 4.IV.2016 ( NMBAP 00323 ) .

Figures

FIGURE 18. Digital microscope photographs of Gymnobisium octoflagellatum Beier, 1947, Female (A, B) and Male (C, D). A, C. Dorsal view; B, D. Ventral view. Scale bar: 1.00 mm.

FIGURE 19. Digital microscope photographs of Gymnobisium octoflagellatum Beier, 1947 right chela: Female (A, B) and Male (C, D). A, C. Retrolateral view; B, D. Dorsal view. Scale bar: 1.00 mm.

FIGURE 20. Gymnobisium octoflagellatum Beier, 1947. 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. Female galea; F. Male galea; G. Female rallum; H. Male rallum. Scale bars: A, B: 0.50 mm; C, D: 0.20 mm; E–H: 0.10 mm.