Chelanops gracilipalpus, Mahnert & Ch-, 2011

Mahnert, Volker, 2011, New records of pseudoscorpions from the Juan Fernandez Islands (Chile), with the description of a new genus and three new species of Chernetidae (Arachnida: Pseudoscorpiones)., Revue suisse de Zoologie 118 (1), pp. 17-29 : 25-29

Chelanops gracilipalpus sp. n. Figs 9-18

MATERIAL STUDIED: MHNG, holotype 3; Chile, Juan Fernandez Islands , Masatierra , forest above Puerto Ingles , 14.XI.1968, leg. H. Franz (Sa 197-198). – MHNG, paratypes 13 3♀ 3 trito-, 5 protonymphs; same data. – NHMW; paratype 1 T; Masatierra, Bahia Cumberland, 200 m, 23.XII.1955, leg. Dr G. Kuschel (recorded by Beier, 1957 as Protowithius robustus Beier ) .

DIAGNOSIS: The presence of accessory teeth on the chelal fingers, a rallum of four blades, the position of trichobothrium ist slightly proximal of est, and the presence of a short tactile seta in the distal third of tarsus IV places the species within the genus Chelanops . It is quite isolated within this genus by its very slender pedipalps (femur 4.5-5.0, patella 3.9-4.3, chela 4.5-4.9 times longer than broad).

DESCRIPTION: Cephalothorax and pedipalps brown, legs yellowish. Cephalothorax parallel-sided, 1.2 times longer than broad, finely granulate, prozone nearly smooth in central part; two transverse granulate furrows, subbasal one slightly closer to posterior margin than to median furrow; no eyes or eyespots; setae short, dentate and clavate, 7 on anterior margin, 14-18 setae on posterior margin and in metazone (Fig. 14). Tergites I-X divided, scaly sculptured, half-tergites mostly with 7-9 setae (Figs 15, 16) on posterior margin and 1 medial seta, from IV-X also with 1 lateral and 1 discal seta, XI with 12 setae (2 lateral tactile and 2 medial discal setae). Manducatory process with 3-4 marginal setae (suboral seta short) and 2 discal setae; pedipalpal FIGS 9-18

Chelanops gracilipalpus sp. n. (9) Left chelicera of holotype 3, with galea of 3 (left) and ♀ (right) (higher magnification). (10-11) Left pedipalp of holotype 3, vestitural setae omitted, some setae shown at higher magnification. (12) Trichobothrial pattern of tritonymph. (13) Trichobothrial pattern of protonymph. (14-16) Setae (higher magnification) on posterior border of cephalothorax (14), on tergite I (15) and on tergite XI (16). (17) Spermatheca with right cribrate plate (ventral view). (18) Left leg IV. Scale units 0.1 mm.

coxae smooth except for a granulate mediodistal zone, coxa I-IV with numerous acute, smooth setae. Male genital chamber with 4 acute setae on each side of entrance; female spermatheca (Fig. 17) with two sac-like tubules; anterior genital operculum of male with about 50 long, acute and curved setae in semi-circular arrangement, that of female with about 40 acute setae (Fig. 17); chaetotaxy of half-sternites: III 9 setae at posterior margin+13 discal setae+4 suprastigmal setae (3) (♀: 14+4 suprastigmal setae), IV 6-8+1-2 suprastigmal setae, V-IX mostly 8-9 (-11) setae,1-2 medial, 1 lateral and 1 discal setae, X 6-7+2+1+4, entire XI 10 (2 lateral and 2 submedial tactile setae). Anal cone 2+2 (dorsal ones clavate, ventral ones dentate). Pleural membrane granulate.

Chelicera (Fig. 9) with 7 (right chelicera with 6) setae, among them 3 internobasal setae with dentate apex, fixed finger with 6-7 retrorse teeth and 3 apical granules, movable finger with tooth-like subapical lobe; galea of male shorter than that of female, with 6 short branchlets, that of female slender, with six long branchlets in distal half; serrula exterior with 24-26 lamellae, rallum composed of 4 dentate setae of decreasing lengths.

Pedipalps (Figs 10-11): femur and hand finely granulate, patella rugose, nearly smooth; setae dentate and indistinctly clavate on paraxial side of femur; trochanter with large dorsal hump, 1.9-2.2 times longer than broad, femur club-shaped (distally broadest), 4.8-5.0 (3)/4.5-4.8 (♀) times, patella 4.1-4.3 (3)/3.9-4.2 (♀) times longer than broad, club 3.3-3.5 (3)/3.0-3.1 (♀) times longer than broad, hand with pedicel 2.5 (3)/2.2-2.5 (♀) times, chela with pedicel 4.9 (3)/4.5-4.8 (♀) times, without pedicel 4.6 (3)/4.2-4.5 (♀) times longer than broad, finger 1.1 times longer than hand with pedicel. Fixed finger with a large series of cone-like sensilla in paraxial basal third, with 90-96 small cusped marginal teeth, with 15-19 antiaxial and 3-6 paraxial accessory teeth; movable finger: 92-100 marginal teeth, 12-17 antiaxial and 1-3 paraxial accessory teeth; venom duct present in movable finger only, nodus ramosus nearer to t than to st; trichobothria arrangement (Fig. 11) with a basal group (eb-esb-ib-isb), ist/est in distal half of fixed finger, ist slightly proximal of est, it/et near fingertip; st nearer to t than to sb.

Leg I: femur 1.8-1.9 times longer than deep, patella 3.9-4.4 times longer than deep and 1.8-1.9 times longer than femur, tibia 6.4-7.1 times and tarsus 7.6-8.5 times longer than deep; leg IV (Fig. 18): femur+patella 5.2-5.3 times, tibia 7.1-7.9 times and tarsus 7.3-9.1 times longer than deep, latter with a short tacile seta (lenght 0.16-0.19 mm) in distal third (TS=0.64-0.77), undivided arolia shorter than smooth claws, subterminal seta smooth, curved.

MEASUREMENTS (in mm): Body length 3.1-3.6 (3)/4.3-4.6 (♀); cephalothorax 1.21-1.25/1.00-1.07 (3) (♀ 1.34/1.07-1.11); pedipalps: trochanter 0.74-0.83/0.39-0.40 (3) (♀ 0.82-0.90/0.40-0.43), femur 1.66-1.72/0.34-0.35 (3) (♀ 1.69-1.71/0.35-0.39), patella 1.57-1.59/0.37-0.38 (3) (♀ 1.60-1.62/0.39-0.41), hand with pedicel 1.40/0.56 (3) (♀ 1.46-1.54/0.62-0.66), finger length 1.50-1.53 (3) (♀ 1.59-1.67), chela length with pedicel 2.73-2.74 (3) (♀ 2.91-2.96), without pedicel 2.56-2.58 (3) (♀ 2.75- 2.80). Leg I: femur 0.42-0.45/0.22-0.25, patella 0.76-0.82/0.18-0.19, tibia 0.84- 0.85/0.13 (3) (♀ 0.88-0.90/0.13), tarsus 0.78-0.85/0.10-0.11; leg IV: femur+patella 1.29-1.32/0.25 (3) (♀ 1.36-1.37/0.26-0.27), tibia 1.11-1.14/0.15-0.16 (3) (♀ 1.17- 1.20/0.15-0.16), tarsus 0.95-0.99/0.11 (3) (♀ 0.99-1.03/0.11-0.12)

FIGS 19-23

Spermathecae (ventral view). (19) Chelanops insularis (S.E.P. 218). (20) Chelanops kuscheli (S.E.P. 218). (21) Chelanops skottsbergi (Masatierra, La Correspondencia) . (22) Pseudopilanus kuscheli (Santiago de Chile). (23) Asterochernes kuscheli Beier (allotype).

Tritonymph (1 specimen): Half-tergites with 6-7 setae on posterior margin, on posterior half-tergites also 1 medial, 1 lateral and 1 discal seta; chelicera with 6 setae on hand, two basal ones dentate, galea slender with 3 apical and 2 subapical branchlets. Chela 4.6 times longer than broad (1.99 mm / 0.43 mm) (no other measurements taken), fixed finger with 71 cusped marginal teeth, 12 antiaxial and 2 paraxial accessory teeth, movable finger with 72 teeth, 5 antiaxial and 1 paraxial teeth; nodus ramosus proximal of trichobothrium t (Fig. 12).

Protonymph (1 specimen): Half-tergites with 3 setae on posterior margin; chelicera with 4 smooth setae on hand, galea long, with 2 apical and 1 subapical branchlets. Chela 4.2 times longer than broad (0.87 mm / 0.21 mm), fixed finger with 29 marginal teeth (13 distal ones cusped, the following rounded) and 1 distal antiaxial accessory tooth; movable finger with 13 cusped teeth and 23 rounded ones; nodus ramosus distal of trichobothrium t (Fig. 13).

ETYMOLOGY: Latin noun, meaning „slender pedipalp“.

DISCUSSION: Chelanops gracilipalpus sp. n. is unique within the genus Chelanops by its very slender pedipalps. It might have affinities with Chelanops insularis (from Masatierra) and Chelanops skottsbergi (Beier) (from Masatierra and Masafuera) (see also Fig. 21: spermatheca), which also have a club-shaped palpal femur and relatively long chelal fingers. In spite of the very divergent proportions and measurement, I do not have any doubts concerning its generic placement, even if there are other discrepancies between the diagnosis of the genus Chelanops given by Muchmore (1999) and the new species (as well as the other Chelanops species from Juan Fernandez Islands): a long, erect tactile seta in the distal half of tarsus IV (here a short tactile seta, merely longer than depth of tarsus); spermatheca having 2 slender tubes of uniform diameter (here two sac-like distal parts with thin basal tubes). These differences do not allow, in my opinion, to place these species in a different genus. Muchmore (1999) described the spermatheca of C. coecus as „occasionally seen as 2 slender tubes of uniform diameter“, and with a long erect tactile seta on tarsus IV. Several females which I identified as C. coecus from Argentina and Chile showed a spermatheca of the same form as that figured for gracilipalpus (and similar to those of kuscheli and insularis ) (Figs 19, 20). Since the spermatheca is delicate and difficult to observe in the large abdomen, the description of the spermatheca given by Muchmore needs to be verified. The long tactile seta seems to break off easily, but I have never observed for C. coecus a short tactile seta as present in gracilipalpus , gracilipes , insularis and kuscheli .

The new species is superficially similar to Protowithius robustus Beier, and Beier (1957) himself confused a tritonymph of C. gracilipalpus sp. n. with P. robustus . Besides the major family differences between Chernetidae and Withiidae, Chelanops gracilipalpus sp. n. is distinguishable at once from P. robustus by its larger size (length of palpal femur 1.66-1.72 mm vs 1.27 mm), more slender pedipalpal patella (ratio 3.9- 4.3 vs 2.8), more slender legs, and its trichobothrial pattern (ist proximal of est, both in middle of the fixed finger, et near finger tip, ist halfway between it and isb).