Ideoblothrus descartes, Harvey & Edward, 2007

Harvey, Mark S. & Edward, Karen L., 2007, A review of the pseudoscorpion genus Ideoblothrus (Pseudoscorpiones, Syarinidae) from western and northern Australia, Journal of Natural History 41 (5 - 8), pp. 445-472 : 465-468

Ideoblothrus descartes sp. nov.

( Figures 36–41 )

Material examined

Holotype: „, Australia: Western Australia: Descartes Island , site DERT01 , 14 ° 099500S, 125 ° 409470E, near freshwater seep, under rocks, 30 August 2002, M. S. Harvey and R. J. Teale ( WAM T 70785). Paratypes: Australia: Western Australia: 1 „, 2♀, same data as holotype ( WAM T 70787– T 70789).

Etymology

The specific epithet is a noun in apposition taken from the type locality, Descartes Island. This island was originally named for the famed French philosopher, mathematician and scientist, René Descartes (1596–1650).

Diagnosis

Ideoblothrus descartes is a medium-sized species of the genus [e.g. pedipalpal patella 0.31– 0.32 mm („), 0.30–0.31 (♀)], notably larger than I. bipectinatus , I. palauensis , and I. milikapiti (patella 0.20–0.22 mm), and smaller than I. aeoodi , I. papillon , I. pisolitus , I. nesotymbus , and I. pugil robustus (patella greater than 0.40 mm). It is approximately the same size as I. pugil [patella 0.33 mm („)], I. ceylonicus (patella 0.28–0.36 mm), and I. aeesti [patella 0.30 mm (♀)], differing from I. pugil by the longer chelal hand versus movable finger ratio (0.94–0.99 in I. descartes and 0.71 in I. pugil ), from I. ceylonicus by the slightly stouter chela [chela (with pedicel) 2.61–2.68 („), 2.60–2.64 (♀) in I. descartes and 2.7–3.0 in I. ceylonicus ] and from I. aeesti by the lack of a strongly angulate externo-basal margin of the chelal hand.

Description

Adults. Colour: pedipalps red orange, carapace, chelicera, and coxae yellow orange, rest of body pale yellow.

Chelicera: five setae on hand, all setae acuminate, is, ls, sbs, and bs long, es very short; movable finger with one sub-distal seta; fixed finger with ca 10 teeth; movable finger with six teeth; with two dorsal lyrifissures and one ventral lyrifissure; male galea short, only very slightly curved and not extending to tip of galeal seta; female galea long, curved and extends to tip of galeal seta; flagellum of five blades, distal blade broadened and finely denticulate; serrula exterior with 21–23 („), 22 (♀) blades.

Pedipalp ( Figure 37 ): internal margins of trochanter, femur, patella and chela with fine granulations; setae on internal margins long and acicular; trochanter without tubercles; trochanter 1.77–1.93 („), 1.85–1.91 (♀), femur 2.43–2.60 („), 2.54–2.58 (♀), patella 1.80– 1.83 („), 1.78–1.89 (♀), chela (with pedicel) 2.61–2.68 („), 2.60–2.64 (♀), chela (without pedicel) 2.41–2.48 („), 2.46–2.50 (♀), hand 1.25–1.29 („), 1.26–1.28 (♀) times longer than broad; movable finger 0.94–0.99 („), 0.94–0.95 (♀) times longer than hand. Femur without tactile setae; without basal projection. Patella with four lyrifissures, two situated dorsally near pedicel, and two situated distally. Fixed chelal finger with eight trichobothria, movable chelal finger with four trichobothria ( Figure 38 ): eb, esb, isb, and ib forming an oblique row on basolateral margin of fixed finger; ist, est, and it situated close together forming a triangle; est situated adjacent to ist; et sub-distal; six small lanceolate setae present on fixed chelal finger; microsetae (chemosensory setae) absent on both fingers; trichobothrium b of movable finger situated sub-basally; sb, st, and t situated medially, close to each other; t lanceolate, slightly shortened, and bent backward. Venom apparatus present only in fixed chelal finger, venom duct very short, nodus ramosus inflated. Fixed finger with 23 („), 25 (♀) slightly retrorse teeth, only extending to level of est ( Figure 40 ); movable finger with 32 („), 37 (♀) rounded teeth, extending nearly to full length of finger ( Figure 41 ); accessory teeth absent. External and internal chelal condyles small and rounded.

Cephalothorax: carapace ( Figure 36 ) 1.26–1.29 („), 1.29–1.32 (♀) times longer than broad; sub-rectangular; without any traces of eyes; epistome present; three specimens (including holotype „) with 24 setae arranged 4: 4: 4: 6: 6, one specimen (paratype ♀) with 25 setae arranged 4: 4: 5: 6: 6; without furrows; with five pairs of small lyrifissures, first and second pairs placed near anterior margin, third pair placed sub-medially, fourth and fifth pairs placed near edge of posterior row. Manducatory process with one long distal and one long sub-distal seta, without sub-oral seta; remainder of maxilla with nine setae ( Figure 41 ). Chaetotaxy of coxae I–IV: 6: 5: 4: 7 („), 6–7: 5: 5–6: 6–7 (♀).

Abdomen: pleural membrane granulo-striate near cephalothorax, remainder longitudinally striate, without setae. Tergites and sternites undivided. Tergal chaetotaxy: holotype „, 6: 7: 9: 9: 9: 9: 9: 9: 9: 7: 6: 2; paratype ♀ ( WAM T 70789), 6: 8: 9: 9: 9: 9: 9: 9: 9: 7: 7: 2; setae uniseriate and acuminate. Sternal chaetotaxy: holotype „, 7: (2) 10 [3+3] (2): (2) 7 (2): 11: 11: 11: 11: 11: 11: 6: 2; paratype ♀ ( WAM T 70789), 6: (2) 7 (2): (2) 8 (2): 11: 12: 12: 11: 11: 11: 6: 2; setae on sternite II of ♀ small; setae uniseriate and acuminate, without medial glandular setae; anus not surrounded by sternite XI .

Genitalia: male genitalia, as far as can be discerned, identical to I. pisolitus ; internal genital glandular setae arranged in two triangular groups of three; pair of setae on edge of sternite III surrounding the antero-median notch of the posterior genital operculum. Female genitalia with single, broad median cribriform plate, and one pair of slender lateral median cribriform plates.

Legs: femora I and II longer than patellae I and II; femora I and II with one transverse lyrifissure situated sub-distally; femur + patella of leg IV 2.64 („), 2.73 (♀) times longer than broad; legs III and IV with articulation between femur and patella segments slightly oblique; tibiae III and IV with medial tactile seta; metatarsi III and IV with sub-basal tactile seta; diplotarsate, all legs with tarsus longer than metatarsus; subterminal tarsal setae not distally serrate; arolia same length as claws, not divided; claws simple.

Dimensions (mm) of „ holotype WAM T 70785 (with „ paratype WAM T 70787 in parentheses, where applicable): body length 1.82 (1.34). Pedipalps: trochanter 0.188 / 0.106 (0.195 / 0.101), femur 0.321 / 0.089 (0.340 / 0.131), patella 0.311 / 0.170 (0.317 / 0.176), chela (with pedicel) 0.543 / 0.208 (0.573 / 0.214), chela (without pedicel) 0.502 (0.531), hand length 0.259 (0.275), movable finger length 0.256 (0.258). Chelicera 0.215 / 0.101 , movable finger length 0.159. Carapace 0.397 / 0.314 (0.406 / 0.314). Leg I: femur 0.127 / 0.075, patella 0.104 / 0.068, tibia 0.148 / 0.044, metatarsus 0.058 / 0.032, tarsus 0.107 / 0.029. Leg IV: femur + patella 0.285 / 0.108, tibia 0.221 / 0.064, metatarsus 0.076 / 0.042, tarsus 0.118 / 0.038.

Dimensions (mm) of ♀ paratype WAM T 70789 (with ♀ paratype WAM T 70788 in parentheses, where applicable): body length 1.74 (0.173). Pedipalps: trochanter 0.195 / 0.102 (0.189 / 0.102), femur 0.330 / 0.130 (0.322 / 0.125), patella 0.302 / 0.170 (0.314 / 0.166), chela (with pedicel) 0.557 / 0.211 (0.554 / 0.213), chela (without pedicel) 0.518 (0.526), hand length 0.269 (0.269), movable finger length 0.256 (0.253). Chelicera 0.222 / 0.099 , movable finger length 0.162. Carapace 0.422 / 0.321 (0.378 / 0.294). Leg I: femur 0.129 / 0.068, patella 0.100 / 0.065, tibia 0.151 / 0.045, metatarsus 0.052 / 0.032, tarsus 0.096 / 0.028. Leg IV: femur + patella 0.284 / 0.104, tibia 0.222 / 0.062, metatarsus 0.069 / 0.042, tarsus 0.118 / 0.036.

Remarks

Ideoblothrus descartes was collected from under rocks at the base of a freshwater seep in Descartes Island, in the Kimberley region of Western Australia ( Figure 1 ).

Figures

Figures 36–41. Ideoblothrus descartes sp. nov., holotype „ unless otherwise stated. (36) Carapace. (37) Left pedipalp, dorsal. (38) Right chela, lateral. (39) Detail of fixed chelal finger, lateral. (40) Detail of movable chelal finger, lateral. (41) Coxal region, ventral, paratype „ (WAM T70787). Scale bars: 0.2 mm (36–38, 41); 0.1 mm (39, 40).

Figures 1, 2. Known distributions of Ideoblothrus species in Western Australia and Northern Territory.