Indohya rixi Harvey & Burger, 2023

Harvey, Mark S., Burger, Mieke A. A., Abrams, Kym M., Finston, Terrie L., Huey, Joel A. & Perina, Giulia, 2023, The systematics of the pseudoscorpion genus Indohya (Pseudoscorpiones: Hyidae) in Australia, Zootaxa 5342 (1), pp. 1-119 : 86-89

Indohya rixi Harvey & Burger , n. sp.

( Figs. 1–3 , 5 , 46 , 47 )

urn:lsid:zoobank.org:act:8A262014-510B-4838-B48E-24ACBA6752F6

Material examined. Holotype male. AUSTRALIA: Western Australia: Mesa C, 37.7 km W. of Pannawonica , 21°41′57″S, 115°57′49″E, 26 May 2013, haul net, J. Alexander ( WAM T144193 ).

Diagnosis. Indohya rixi most closely resembles I. adlardi and I. sachsei as all three possess 14 setae on the carapace arranged 4: 2: 4: 2: 2 and they lack eyes ( Fig. 47A ). It differs from them by its smaller size, e.g. chela (with pedicel) 1.055 (Ô) mm (1.865 –2.005 (♀) mm in I. adlardi and 1.22–1.27 (♀) mm in I. sachsei ). It further differs from I. sachsei by trichobothrium sb being slightly closer to st than to b (ratio sb–st / sb–b = 1.16) [sb much closer to st than to b (ratio = 2.63) in I. sachsei ].

There are no unique nucleotide substitutions in COI mtDNA that distinguish this species from all other species of Indohya . The single sequenced specimen differs from all other sequenced specimens of Indohya by 9.1–26.4% (Table 2).

Description (adult). Colour ( Fig. 46 ): pale yellow-brown.

Setae and cuticle: setae long, mostly straight and acicular; most cuticular surfaces smooth and glossy.

Chelicera: surface smooth; hand with 6 (Ô) setae, movable finger with 1 sub-medial seta, all setae acuminate; galea present, long, slender and slightly curved; fixed finger with 14 small (Ô), each approximately same size; movable finger with ca. 9 small (Ô) teeth, each approximately same size; with 2 dorsal and 1 ventral lyrifissures; lamina exterior absent; rallum with 6 blades, all blades with anterior spinules, basal blade shorter than others.

Pedipalp ( Fig. 47B ): long and slender; trochanter smooth, 2.55 (Ô) ×; femur slightly broadened distally, smooth, without dorsal tactile seta, with 3 stout retrolateral setae near base, 6.55 (Ô) ×; patella slightly broadened distally, smooth, pedicel not strongly pronounced but basal portion slimmer than distal portion, with 4 lyrifissures situated basally on dorsal surface, including 3 long and 1 short lyrifissure, 4.24 (Ô) ×; chela ( Fig. 47C ): hand ovoid or slender, smooth, chela (with pedicel) 5.02 (Ô) ×, chela (without pedicel) 4.79 (Ô) ×, hand (without pedicel) 1.83 (Ô) × longer than broad, movable finger 1.60 (Ô) × longer than hand (without pedicel). Fixed finger with 8 trichobothria, eb, esb and isb in straight row at base of finger, ib situated dorsally at the end of the chelal hand, isb at the basal end of the fixed finger, ib situated on dorsum of chelal hand, it closer to et than to est, et slightly distal to it; movable finger with 4 trichobothria, sb closer to b than to st, st situated much closer to t than to sb, ratio sb–st / sb–b = 1.81 (Ô), t acuminate. Both fingers straight in lateral view. Fixed finger smooth, movable finger with several retrolateral granulations basally. Chelal teeth ( Figs. 47D, E ) juxtadentate, fixed finger with 62 (Ô) teeth, teeth 1–3, 47–48, 50–52 pointed, remainder rounded, movable finger with ca. 25, low teeth or triangular, strongly retrorse teeth. Venom apparatus present only in movable chelal finger, venom duct long, terminating in nodus ramosus between sb and st.

Cephalothorax: carapace ( Fig. 47A ) sub-rectangular; smooth; anterior margin slightly convex; epistome absent; lateral margins slightly convex; posterior margin straight; 1.26 (Ô) × longer than broad; with 14 setae arranged 4: 2: 4: 2: 2 (Ô); without furrows; eyes absent. Manducatory process distally triangular, with 2 distal setae; pedipalpal coxa with 7 (Ô) additional setae. Coxa I with anterior margin not modified; chaetotaxy of coxae I–IV: Ô, 4: 4: 3: 4.

Legs: femora I and II much longer than patellae I and II, respectively; femora I and II with basal swelling; femora I and II each with 2 slit sensilla, each directed transversely; junction between anterior femora and patellae perpendicular; junction between posterior femora and patellae slightly oblique; femora III and IV much smaller than patellae III and IV, respectively; femur + patella IV 4.96 (Ô) × longer than broad; metatarsi shorter than tarsi; subterminal tarsal seta acuminate; claws smooth, arolium slightly shorter than claws; arolium not divided.

Abdomen: tergites not divided; tergal chaetotaxy Ô, 4: 4: 6: 6: 6: 6: 6: 5: 6: 4: 4: 2; arranged in single rows; sternal chaetotaxy Ô, 16: (2) 15 [2 + 2] (2): (2) 4 (2): 8: 6: 6: 6: 6: 6: 4: 2; posterior tergites and sternites with several tactile setae; medial sternites without suture line; pleural membrane uniformly granulate; without setae; stigmatic helix present.

Genitalia: male: lateral genital sacs large and ovoid; median genital sac short and ovoid; ejaculatory duct atrium large and rounded; dorsal apodeme wing-like; without a pair of large dorsal genital sacs; with 2 pairs of setae within genital atrium.

Dimensions (mm): male holotype ( WAM T144193 ). Body length (excluding chelicerae) 1.41. Pedipalp : trochanter 0.255 / 0.100 , femur 0.720 / 0.110, patella 0.530 / 0.125, chela (with pedicel) 1.055 / 0.210, chela (without pedicel) length 1.005, chelal hand (without pedicel) length 0.385, movable finger length 0.615. Carapace 0.490 / 0.390 . Leg IV: femur + patella 0.505 / 0.120, tibia 0.350 / 0.065, metatarsus 0.100 / 0.050, tarsus 0.315 / 0.045.

Distribution and remarks. Indohya rixi has only been found from subterranean habitats in Mesa C, in the western Pilbara ( Fig. 5 ). The species was previously known by WAM identification code Indohya ‘PSE170’.

There are no observable morphological differences between I. rixi and I. adlardi , other than size, e.g. the chela length (with pedicel) is 1.055 mm in the sole male of I. rixi , and 1.865 –2.005 mm in six females of I. adlardi . Although male hyids are generally slightly smaller than females, the size difference between this species pair is considerable with the females of I. adlardi being nearly twice as large as the male of I. rixi . Furthermore, they occur in adjacent but separate mesas in the Robe River Valley ( Fig. 5 ).

Conservation assessment. Mesa C is a small mesa in the Robe River Valley which is scheduled to be developed into an iron ore mine in which the vast majority of the subterranean habitat will be extracted. Like other troglobitic arthropods that occur in the subterranean environment of Mesa C, it is highly unlikely that I. rixi occurs in any nearby environments, as these mesas are occupied by other species of Indohya . The combination of small distribution and potential loss of available habitat if the mine commences suggests that this species is Vulnerable (B2ab[iii]) using the criteria developed by the International Union for Conservation of Nature (2012).

Etymology. This species is named for our friend and colleague Mike Rix in appreciation for his contributions to systematic research.

Figures

FIGURE 1. Maximum likelihood phylogeny of Hyidae and other neobisioids, based on alignment of concatenated COI, 18S and 28S. Ultrafast bootstrap values are presented for nodes greater than 80%.

FIGURE 2. Maximum likelihood phylogeny of Australian Indohya, using COI, 18S and 28S concatenated dataset. Bootstrap values are presented for all nodes. The genes amplified for each specimen are depicted with black squares in the gene matrix.

FIGURE 3. Maximum likelihood phylogeny of Australian Indohya, using COI. Bootstrap values are presented for all nodes.

FIGURE 5. Maps of north-western Australia depicting recorded distributions of the subterranean species of Indohya from the Pilbara and Cape Range region.

FIGURE 46. Indohya rixi Harvey & Burger, n. sp., holotype male (WAM T144193): A, dorsal; B, ventral; C, cephalothorax, dorsal. Scale lines = 1.0 mm.

FIGURE 47. Indohya rixi Harvey & Burger, n. sp., holotype male (WAM T144193): A, carapace, dorsal; B, right pedipalp, dorsal; C, left chela, retrolateral; D, left fixed finger, chelal teeth, retrolateral; E, left movable finger, chelal teeth, retrolateral. Scale lines = 0.5 mm (Figs. B, C), 0.2 mm (Fig. A), 0.1 mm (Figs. D, E).