Tyrannochthonius eua, 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

Tyrannochthonius eua sp. nov. Figs 1 , 2 , 3

Material examined.

Holotype: Polynesia • ♂; Tonga, Eua [-21.387, -174.930]; 215 m a.s.l.; 11 Jul. 1980; Galina Fedorovna Kurcheva leg.; moss; NHMW 29197.

Description.

Adult male (Figs 2 , 3 ). Carapace (Fig. 3A ): 0.97 × longer than broad; with four corneate eyes; epistome present, triangular; with 18 setae arranged 6: 4: 4: 2: 2; without furrows; with two pairs of small lyrifissures, first pair situated in ocular row, second pair situated lateral to setae of posterior row. Coxae (Fig. 3B ): coxa I with rounded apical projection, not bearing microsetae; chaetotaxy of coxae (Fig. 3B ): palpal coxae 3; pedal coxae I 3, II 4, III 5, IV 5. Coxa II with eight terminally incised spines, set in an oblique row (Fig. 3B, C ). Intercoxal tubercle absent. Chelicera (Fig. 3D ): 1.53 × longer than broad; five setae on hand, all acuminate; moveable finger with one medial seta; fixed finger with 11, moveable finger with nine teeth; one ventral and two dorsal lyrifissures on hand; galea absent; serrula exterior with 15 blades; rallum consisting of seven bipinnate blades. Pedipalp (Fig. 3E ): all setae acuminate, femur setal formula: 5: 2: 1: 3: 5; trochanter 1.44 ×, femur 4.11 ×, patella 2.11 ×, chela 5.18 ×, hand 2.18 × longer than broad. Hand without spine-like seta, dorsal surface with a single row of five chemosensory setae between trichobothria esb and ib / isb; hand and fixed chelal finger together with eight trichobothria, moveable chelal finger with four trichobothria; ib and isb close together, submedially on dorsum of chelal hand; eb and esb close together, at base of fixed finger; ist distal to eb and esb; it and est less than one areolar diameter apart, it slightly distal to est; et near tip of finger; trichobothrium st of moveable finger sub-basally; sb slightly closer to st than to b; b and t subdistally, t at same level as it; b slightly basal to est. Chelal teeth heterodentate: fixed finger with three small teeth followed by 17 large, erect, well-spaced teeth, decreasing in size towards base, distally alternating with six small intercalary teeth; moveable finger with nine large, erect, well-spaced teeth, without intercalary teeth. Opisthosoma: tergites and sternites undivided; setae uniseriate and acuminate. Tergal chaetotaxy I-IX: 4: 4: 4: 4: 4: 5: 6: 6: 6. Sternal chaetotaxy II-IX: 10: 28: 15: 10: 10: 8: 8: 8 (Fig. 3F ). Sternal lyrifissures II-IX: 2: 2: 0: 0: 0: 0: 0: 0. Genitalia: sternite III with narrow V-shaped opening. Genitalia not studied in detail. Leg I: trochanter 1.13 ×, femur 4.40 ×, patella 2.75 ×, tibia 3.25 ×, tarsus 5.67 × deeper than broad. Leg IV: trochanter 1.22 ×, femoropatella 1.88 ×, tibia 3.43 ×, metatarsus 2.00 ×, tarsus 6.67 × deeper than broad. Tactile seta present on metatarsus of leg IV; arolium slightly shorter than claws, not divided; claws simple.

Dimensions (length/width or, in the case of the legs, length/depth) in mm. Body length 1.10. Pedipalp: trochanter 0.13/0.09, femur 0.37/0.09, patella 0.19/0.09, chela 0.57/0.11, hand 0.24/0.11, fixed finger 0.31, moveable finger 0.33. Chelicera 0.26/0.17, moveable finger 0.15. Carapace 0.38/0.39. Leg I: trochanter 0.09/0.08, femur 0.22/0.05, patella 0.11/0.04, tibia 0.13/0.04, tarsus 0.17/0.03. Leg IV: trochanter 0.11/0.09, femoropatella 0.32/0.17, tibia 0.24/0.07, metatarsus 0.12/0.06, tarsus 0.20/0.03.

Etymology.

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

Remarks.

The presence of intercalary teeth on the fixed chelal finger but not on the moveable chelal finger is unusual in Tyrannochthonius species. However, a few other species possess this combination: T. convivus Beier, 1974, T. brasiliensis Mahnert, 1979, T. amazonicus Mahnert, 1979, T. rex Harvey, 1989, and T. swiftae Muchmore, 1993 ( Beier 1974; Mahnert 1979; Harvey 1989; Muchmore 2000). Tyrannochthonius eua sp. nov. differs from T. convivus , T. amazonicus , T. rex , and T. swiftae by the significantly shorter palpal femur length (0.37 mm, versus 0.42-0.49 mm in T. convivus , 0.46-0.56 mm in T. amazonicus , 1.24-1.34 mm in T. rex , and 0.53 mm in T. swiftae ). It also differs from T. amazonicus , T. rex , and T. swiftae in having a lower number of teeth on fixed chelal fingers. In contrast, T. brasiliensis has a shorter palpal femur (length 0.28 mm) than T. eua sp. nov., as well as lower number of coxal spines on coxae II (4-5, versus 8 in T. eua 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 2. Tyrannochthonius eua sp. nov., holotype male, dorsal. Scale bar: 1 mm.

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.