Nesocheiridium onevai, Krajčovičová & Matyukhin & Jana Christophoryová, 2020

Krajcovicova, Katarina, Matyukhin, Aleksandr Vladimirovich & Jana Christophoryova,, 2020, Two new pseudoscorpion species (Pseudoscorpiones, Chthoniidae, Cheiridiidae) from the Tonga Islands, Polynesia, with a redescription of the genus Nesocheiridium, ZooKeys 927, pp. 37-51 : 37

Nesocheiridium onevai sp. nov. Figs 1 , 4B , 6

Material examined.

Holotype: Polynesia • ♀; Tonga, Onevai [-21.087, -175.115]; 7 m a.s.l.; 10 Jun. 1980; Galina Fedorovna Kurcheva leg.; moss; NHMW 29188.

Description.

Adult female (Figs 4B , 6 ). Integument coarsely granulate, dorsally granuloreticulate (Fig. 6B, C ). Vestitural setae arcuate with a small spine, often covered by a fine exudate, giving them a leaf-like shape. Carapace (Fig. 6A ): 0.72 × longer than broad, subtriangular; cucullus short; two distinct eyes with lenses; two lateral lighter sections at the level of the eyes (this is not due to damage); submedian transverse furrow deep (carapace slightly damaged in middle); anterior disk laterally with two protuberances, posterior disk with a shallow medial depression in its middle (Fig. 6A ); with 30 leaf-like setae (20 before furrow, 10 behind); with one pair of lyrifissures in ocular area. Chelicera (Fig. 6D ): 1.80 × longer than broad; four setae on hand, all acuminate; moveable finger with one short seta; fixed finger with two teeth near tip; with two lyrifissures on hand; galea long, slender, with three apical rami; serrula exterior with 10 blades; rallum consisting of four blades (Fig. 6E ). Coxae (Fig. 6F ): coarsely granulate; chaetotaxy: manducatory process two or three acuminate setae, rest of palpal coxa with four acuminate and two leaf-like setae, situated in anterior half; pedal coxae I 5-7 acuminate setae, II 6-8 acuminate setae, III seven or eight acuminate setae, IV eight or nine acuminate setae. Lyrifissures: one on coxa III, one on coxa IV; maxillary lyrifissures not visible.

Pedipalp (Fig. 6G-J ): coarsely granulate; trochanter with distinct dorsal hump; patella markedly broadened mesally, with a distinct pedicel (Fig. 4B ). Trochanter 1.56 ×, femur 3.25 ×, patella 2.10 ×, chela 2.60 ×, hand with pedicel 1.40 × longer than broad. Chela, including the base of the fixed finger, coarsely granulate (Fig. 6J ). Venom apparatus present in both fingers. Fixed chelal finger with seven trichobothria, moveable chelal finger with two trichobothria. Fixed chelal finger with 10 flat marginal teeth; moveable finger with four flat marginal teeth. Fixed finger with granulate swelling mesally (Fig. 6H ), trichobothria ib and ist distad of swelling. Trichobothrial pattern as in Figure 6I . Opisthosoma: Tergal chaetotaxy: 3+4: 4+4: 5+5: 6+7: 7+7: 7+7: 6+7: 7+6: 5+5: 4+3; I-X with leaf-like setae. Tergites without lyrifissures. Tergal pores I-X: 0+0: 1+2: 1+2: 2+2: 1+2: 2+2: 1+2: 2+2: 0+0: 0+0. Sternal chaetotaxy (Fig. 6K ): 5+4 small entrance setae: 10: 4+5: 6+6: 6+7: 7+7: 7+7: 7+7: 5+4: 3+3; II-VIII with acuminate setae, IX-XI with leaf-like setae. Sternal lyrifissures II-XI: 1+1: 2: 0+0: 1+2: 1+1: 1+1: 1+1: 1+1: 1+1: 0+0. Sternal pores II-XI: 6: 0: 5+5: 5+5: 5+4: 0+1: 0+0: 0+0: 1+1: 3+4. Anal opercula: each with two short, acuminate setae. Anterior genital operculum with sternal plates divided. Genitalia not studied in detail. Leg I (Fig. 6L ): trochanter 1.00 ×, femoropatella 3.00 ×, tibia 2.75 ×, tarsus 4.33 × longer than deep. Leg IV (Fig. 6M ): trochanter 1.67 ×, femoropatella 3.80 ×, tibia 3.75 ×, tarsus 5.33 × longer than deep. No tactile setae present; claws simple.

Dimensions (length/width or, for legs, length/depth) in (mm). Body length 0.85. Pedipalp: trochanter 0.14/0.09, femur 0.26/0.08, patella 0.21/0.10, chela 0.39/0.15, hand with pedicel 0.21/0.15, hand without pedicel 0.19, moveable finger 0.18. Chelicera: 0.09/0.05, moveable finger 0.07. Carapace 0.28/0.39. Leg I: trochanter 0.05/0.05, femoropatella 0.15/0.05, tibia 0.11/0.04, tarsus 0.13/0.03. Leg IV: trochanter 0.10/0.06, femoropatella 0.19/0.05, tibia 0.15/0.04, tarsus 0.16/0.03.

Etymology.

The species epithet refers to the island Onevai, on which this species occurs. It is used as a noun in apposition.

Remarks.

The two species currently placed in the genus are easy to distinguish from each other by the form of the carapace ( N. stellatum lacks a medial depression on the posterior disk, whereas N. onevai sp. nov. has a weak medial depression on the posterior disk); the shape of the palpal patella (not broadened in N. stellatum , versus markedly broadened mesally in N. onevai sp. nov.); the number of setae on the carapace (43 in N. stellatum , 30 in N. onevai sp. nov.); the number of marginal teeth on the fixed chelal finger (16 in N. stellatum , 10 in N. onevai sp. nov.); the shape of the setae on sternite VIII (leaf-like in N. stellatum , as opposed to acuminate in N. onevai sp. nov.); and the lengths of the palpal segments (femur 0.33 mm in N. stellatum , 0.26 mm in N. onevai sp. nov.; patella 0.26 mm in N. stellatum , 0.21 mm in N. onevai sp. nov.; hand with pedicel 0.28 mm in N. stellatum , 0.21 mm in N. onevai sp. nov.).

Figures

Figure 1. Distribution of the studied species: Tyrannochthonius eua sp. nov. (yellow triangle), Nesocheiridium stellatum (white circle), N. onevai sp. nov. (red circle).

Figure 3. Tyrannochthonius eua sp. nov., holotype male, dorsal A carapace B coxae C coxal spines D right chelicera E right chela, showing trichobothrial pattern F chaetotaxy of genital area (sternites II-III). Abbreviations: trichobothria of moveable chelal finger: t - terminal, b - basal, sb - subbasal, st - subterminal; trichobothria of fixed chelal finger: dx - duplex trichobothria, et - exterior terminal, it - interior terminal, est - exterior subterminal, ist - interior subterminal, esb - exterior subbasal, eb - exterior basal, isb - interior subbasal, ib - interior basal. Scale bars: 0.1 mm.

Figure 4. Nesocheiridium species, dorsal view A N. stellatum, holotype male B N. onevai sp. nov., holotype female. Arrow indicates widening of palpal patella. Scale bar: 0.5 mm.

Figure 6. Nesocheiridium onevai sp. nov., holotype female A carapace (damaged part cross-hatched) B, C details of granulation types on carapace D right chelicera E rallum F coxae G right palp minus chela H chelal fingers, ventro-lateral view, showing swelling on fixed finger I right chela J detail of granulation on chela K chaetotaxy of genital area (sternites II-III) L right leg I M right leg IV. Abbreviations as for Figure 3. Scale bars: 0.1 mm.