Indohya silenda Harvey & Burger, n. sp.

(Figs. 1–3, 5, 52, 53)

urn:lsid:zoobank.org:act: F69277D0-9F8A-4E4C-B565-54DAB7D66D19

Material examined. Holotype deutonymph. AUSTRALIA: Western Australia: Western Ridge, ca. 5 km SW. of Newman, 23°24′51.12″S, 119°33′31.95″E, 1 February–7 April 2020, troglofauna trap, depth 20 metres, M.K. Curran, A.J. Mittra (WAM T140487).

Diagnosis. Indohya silenda is a blind troglobite that differs from all other Indohya species for which sequence data are available by a synapomorphy in COI mtDNA: at base 538 there is a substitution to G. The single sequenced specimen differs from all other sequenced specimens of Indohya by 16.5–26.2% (Table 2).

Description (deutonymph). Colour (Fig. 52): Very pale, yellow-white.

Chelicera: hand with 5 setae, movable finger with 1 sub-medial seta.

Pedipalp: trochanter 2.11 ×, femur 6.12 ×, patella 3.58 ×, chela (with pedicel) 4.72 ×, chela (without pedicel) 4.66 ×, hand (without pedicel) 1.81 × longer than broad, movable finger 1.41 × longer than hand (without pedicel). Fixed finger with 6 trichobothria (Fig. 53B), eb, est, et, ib, ist and it present; movable finger with 2 trichobothria, b and t present. Fixed chelal finger with 39 low teeth (Fig. 53B); movable chelal finger with 23 low teeth.

Cephalothorax: carapace 1.31 × longer than broad; with 12 setae, arranged 4: 0: 4: 2: 2; without furrows; eyes absent. Coxal chaetotaxy 3: 3: 3: 3.

Abdomen: missing.

Legs: all missing.

Dimensions (mm): holotype (WAM T140487). Pedipalp: trochanter 0.190 / 0.090, femur 0.520 / 0.085, patella 0.340 / 0.095, chela (with pedicel) length 0.755 / 0.160, chela (without pedicel) length 0.745, hand (without pedicel) length 0.290, movable finger length 0.410. Carapace 0.360 / 0.275.

Distribution and remarks. This blind, troglobitic species is currently represented only by a single deutonymph collected from Western Ridge in the south-western Pilbara region of Western Australia (Fig. 5). Based on available sequence data (Table S4), this species is noticeably different from other species, and the sole specimen is situated on a long genetic branch (Figs. 1–3). The species was previously known by WAM identification code Indohya ‘PSE172’.

Conservation assessment. Indohya silenda is only known from a subterranean biotope, but it is unknown whether it is more widely distributed in the local area. The total extent of the subterranean habitat and I. silenda ’s distribution is unknown. Despite relatively intensive subterranean sampling of the area, no more specimens have been collected of this species. The species may be impacted by future mining developments but insufficient information is available currently to determine its status using the criteria developed by the International Union for Conservation of Nature (2012).

Etymology. The specific epithet refers to the use of molecular sequence data to establish that this nymphal specimen represents a distinct species (silendum, Latin, mystery, secret) (Brown 1956).