Hormurus ischnoryctes Monod & Prendini, 2013

Monod, Lionel, Harvey, Mark S. & Prendini, Lorenzo, 2013, Stenotopic Hormurus Thorell, 1876 scorpions from the monsoon ecosystems of northern Australia, with a discussion on the evolution of burrowing behaviour in Hormuridae Laurie, 1896, Revue suisse de Zoologie 120 (2), pp. 281-346 : 301-314

Hormurus ischnoryctes Monod & Prendini , n. spec. Figs 12-21, 38B, D, Table 2

HOLOTYPE: QM; Ƌ; Australia, Queensland, Mount Mulligan cattle station, 16º50'S, 144º50'E; 16-17.VII.2006; 340 m, open woodland savanna, in vertical burrows 15-30 cm deep, with terminal chambers, G. Romand & L. Monod .

PARATYPES: AMNH, without registration number; 1 Ƌ, 4 ♀, 5 imm.; same data as holotype. – QM; 3 ♀, 4 imm.; same data as holotype. – AMCC LP 6639; 1 imm.; same data as holotype. – QM-S17140; 1 Ƌ; Mount Mulligan [16º51'Ex 144º50'S]; 10.IX.1983; A. Williamson .

OTHER MATERIAL: MNHN RS 4209; 1 Ƌ, 1 ♀; Ravenshoe [145º29'0''S, 17º37'59''E]; VIII.1963; ca. 600 m, open Eucalyptus forest , marked cold season, low rainfall, H. St Girons .

ETYMOLOGY: The name ischnoryctes is constructed from the Greek words ischnos [thin, lean] and oryktes [digger]. It is an invariable noun in apposition and refers to the male pedipalps, which are unusually long and slender compared to those of other fossorial hormurids.

DIAGNOSIS: Hormurus ischnoryctes differs from other Australian species of the genus as follows. The base colouration of the cuticle is noticeably more reddish in H. ischnoryctes than in other species. The carapace is medially smooth or nearly so (only weakly granular around the median ocelli of the adult male) in H. ischnoryctes , whereas in other species it is granular, at least posteriorly. The prolateral process of the pedipalp patella is less developed in H. ischnoryctes than in other species except H. ochyroscapter . Mesosomal post-tergites I-IV of the adult male are smooth medially and granular laterally in H. ischnoryctes whereas in other species they are completely granular. The metasomal intercarinal surfaces of the female are smooth or nearly so in H. ischnoryctes whereas in other species they are at least sparsely granular.

DESCRIPTION OF ADULT MALE: Colouration: Dorsal surface of chelicera manus orange to brown; fingers dark brown to black (Fig. 12). Carapace reddish brown, with darker areas. Pedipalps red to reddish brown; carinae and fingers reddish brown to black. Legs orange to brown. Tergites brown to dark brown, slightly paler than carapace, without red tinge. Coxapophyses, sternum, genital operculum, pectines and sternites pale orange to brown. Metasoma brown to dark brown. Telson orange to pale brown; aculeus reddish-black.

Cuticle: Non-granular surfaces of carapace, pedipalps and legs, mesosoma, and metasoma finely punctate.

Carapace: Anterior margin with shallow median notch (Fig. 14A). Anterior furcated suture and sulci distinct. Median ocular tubercle situated anteromedially, at least slightly raised, small, occupying about 1/6-1/7 of carapace width; superciliary carinae present, smooth; median ocelli present, at least twice the size of lateral ocelli, separated by at least half the diameter of a median ocellus. Three pairs of lateral ocelli,

FIG. 12

Hormurus ischnoryctes n. spec., male, dorsal aspect, reconstruction based on scientific illustrations and photographs of live specimens. Scale, 5 mm.

FIG. 13

Hormurus ischnoryctes n. spec., habitus, dorsal (A, B) and ventral (C, D) aspect. (A, C) Holotype male (QM). (B, D) Paratype female (QM). Scale, 5 mm.

equal in size, equidistant and adjacent to one another. Postocular carapace margin aspinose. Surfaces of frontal lobes smooth; surfaces adjacent to anterior furcated and median longitudinal sulci finely granular (Fig. 14C); median and lateral surfaces finely and at least sparsely granular; posteromedian surfaces smooth.

Chelicerae: Median and basal teeth of fixed finger fused into a bicusp. Dorsal margin of movable finger with four teeth (one subdistal and one basal); dorsal distal tooth smaller than ventral distal tooth; ventral margin smooth.

Pedipalps: All segments slightly elongated (Figs 12, 13A, C, 15B-E, G-J, L-O, 16A), with femur length slightly longer than carapace length (Tab. 2). Chela almost TABLE 2. Hormurus ischnoryctes n. sp., measurements (in mm) of adult males and females.

Holotype Paratype Paratype Paratype Paratype

Sex Ƌ Ƌ Ƌ ♀ ♀ ♀

Repository QM QM-S AMNH QM QM AMNH 17140

Locality Mount Mount Mount Mount Mount Mount Mulligan Mulligan Mulligan Mulligan Mulligan Mulligan cattle cattle cattle cattle cattle cattle station station station station station station

Total length 55.0 48.0 46.0 59.0 58.0 51.0 Carapace, length 7.2 7.6 6.8 8.1 7.9 7.8 Carapace, anterior width 5.3 5.5 4.8 5.9 5.5 5.6 Carapace, posterior width 7.6 8.7 7.2 8.4 7.8 7.7 Chela, length 17.2 17.9 15.1 16.5 14.9 14.6 Chela manus, width 4.7 4.9 4.5 5.7 5.5 5.3

Chela manus, heigth 3.1 3.1 2.8 3.7 3.4 3.1

Chela movable finger, length 7.6 8.5 6.9 8.4 7.6 7.1 Patella, length 9.1 9.2 7.8 7.9 7.3 7.0 Patella, width 3.6 3.6 3.1 3.8 3.7 3.4 Femur, length 9.0 9.5 7.8 7.4 7.1 6.8 Femur, width 3.0 3.0 2.7 3.2 3.0 3.1 Metasomal segment I, length 3.5 2.9 3.2 3.5 3.0 3.1 Metasomal segment I, width 1.9 2.1 1.6 2.0 1.9 2.0 Metasomal segment V, length 4.4 4.2 4.3 4.6 4.2 4.2 Metasomal segment V, width 1.2 1.4 1.1 1.3 1.3 1.3 Metasomal segment V, height 1.48 1.46 1.25 1.51 1.38 1.45 Telson vesicle, width 1.64 1.6 1.41 1.58 1.41 1.44 Telson vesicle, height 1.7 1.45 1.6 1.69 1.6 1.57

asetose. Chela fingers: Dentate margins of fixed and movable fingers linear (without lobe and notch) distally, with two rows of primary denticles, these rows fused to each other basally; larger primary denticles located at regular intervals in each row, accessory denticles absent. Fixed finger: Suprabasal lobe well developed, conical; suprabasal notch distinct and deep (Fig. 16A). Movable finger: Basal lobe absent or reduced to a few small spiniform granules; suprabasal lobe well developed, wider than high, gently rounded dorsally and lacking a sharp conical tooth, not overlapping fixed finger; suprabasal lobe and corresponding suprabasal notch of fixed finger contiguous, no proximal gap or at most a reduced gap evident when fingers closed. Pedipalp carinae: Femur (Fig. 15L-O): Dorsoexternal carina costate, usually more distinct in proximal half; dorsointernal carina distinct, more strongly developed than dorsoexternal carina; internomedian dorsal carina vestigial, without spiniform granules or with one large spiniform granule situated medially on segment; internomedian ventral carina vestigial, comprising two large spiniform granules situated proximally and medially on segment; ventromedian carina obsolete; ventrointernal carina distinct. Patella (Fig. 15G-J): Prolateral process distinct but reduced, forming single large spine; internodorsal and dorsomedian carinae distinct; dorsoexternal carina obsolete; externomedian carina granular; ventroexternal carina distinct, costate-granular. Chela manus (Fig. 15B-E): Dorsal secondary carina obsolete; digital carina distinct, granular, more strongly developed than external secondary carina; external secondary carina obsolete; FIG. 14

Hormurus ischnoryctes n. spec., carapace and mesosomal tergites illustrating ornamentation and macrosculpture of cuticle (A, B), with detailed view of carapace (C, D) and tergite V (E, F), dorsal aspect. (A, C, E) Holotype male (QM). (B, D, F) Paratype female (QM). Scale, 2 mm (A, B), 1 mm (C-F).

FIG. 15

Hormurus ischnoryctes n. spec., pedipalp chela (A-E), patella (F-J), femur and trochanter (K-O), dorsal (A, B, F, G, K, L), retrolateral (C, H, M), ventral (D, I, N) andprolateral (E, J, O) aspect illustrating trichobothrial pattern. (A, F, K) Paratype female (QM). (B-E, G-J, L-O) Holotype male (QM). Scale, 2 mm.

FIG. 16

Hormurus ischnoryctes n. spec., pedipalp chela, retrolateral aspect illustrating dentate margin of chela fingers. (A) Holotype male (QM). (B) Paratype female (QM). Scale, 1 mm.

ventroexternal carina granular to crenulate; ventromedian carina obsolete; ventrointernal carina reduced to row of small granules; internomedian carina distinct, sparsely granular. Pedipalp surface macrosculpture: Femur (Fig. 15L-O): Dorsal intercarinal surface densely granular except distally; pro- and retrolateral intercarinal surfaces at least sparsely granular; retrolateral intercarinal surface smooth or nearly so ventrally; ventral intercarinal surface granular proximally, smooth distally. Patella (Fig. 15G-J): Dorsal and retrolateral intercarinal surfaces granular or at least comprising a reticulated network of granules; ventral intercarinal surface sparsely granular, distal extremity smooth; prolateral intercarinal surface sparsely granular proximally, usually less so in distal half. Chela (Fig. 15B-E): Dorsal intercarinal surface of manus densely granular, comprising medium-sized granules; retrolateral intercarinal surface granular; ventral intercarinal surface granular along pro- and retrolateral margins only, smooth medially; prolateral intercarinal surface granular. Chela fingers granular, at least sparsely so in proximal half; db, dsb and dst trichobothria of fixed finger each situated in a smooth depression, surfaces around depressions granular (at least in proximal part of finger). Trichobothria: Pedipalps orthobothriotaxic, accessory trichobothria absent (Fig. 15B-E, G-J, L-O). Patella d 2 situated distal to patellar process; five eb trichobothria arranged in two groups, eb 1 and eb 2-5 or eb 1 / eb 4-5 and eb 2-3; two esb trichobothria; two em trichobothria; one est trichobothrium; three et trichobothria; three V trichobothria. Chela manus with Dt situated in proximal third; Eb 3 situated close to Eb 1-2; Esb situated distal to Eb series and close to Est; Est situated at or near midpoint; four V trichobothria, with V 3 and V 4 separated. Chela fixed finger with db situated on dorsal surface; eb, esb, est and et equidistant (distance esb-est similar to distance ebesb); eb situated at base of finger, behind point of articulation between fixed and movable fingers, aligned with esb-et axis; esb situated proximally on fixed finger, aligned with est-et axis; two i trichobothria.

Coxosternum: Leg III coxae without swelling or bulge anterodistally. Sternum equilateral pentagonal (Fig. 17A); anterior width slightly greater than posterior width; length less than or equal to posterior width.

Legs: Femora I-IV each with ventral surfaces bicarinate (proventral carinae less developed than retroventral carinae); IV with ventral carinae vestigial (only expressed distally) and indistinct, reduced to scattered granules. Retroventral margins of tibiae I and II without setiform macrosetae. Pro- and retroventral margins of basitarsi I-IV each with 4 setiform macrosetae. Telotarsi I-IV: Pro- and retroventral margins each with 4/4, 4/4, 5/4-5, 5-6/5 setiform macrosetae, respectively (Fig. 18D, E); ventromedian row of spinules reduced to few spinules basally, terminal ventromedian spinules absent; dorsomedian lobe pronounced; laterodistal lobes truncate; ungues curved, shorter than telotarsus.

Genital operculum: Composed of two subtriangular sclerites (Fig. 17A).

Pectines: Slightly elongated, distal edge reaching but not surpassing distal edge of leg IV coxa (Fig. 17A); fulcra and three marginal lamellae present. Pectinal tooth count 8-10; teeth long and straight, entirely covered by sensory papillae.

Mesosoma : Posterior margins of pre-tergites I-VII smooth (Fig. 14A, E). Posterior margins of post-tergites I-VII sublinear, without distinct prominence (Fig. 14A, E); I-VI each with lateral transverse sulci; intercarinal surfaces of I-IV smooth medially, finely granular posterolaterally, at least sparsely so; intercarinal surfaces of III-VII uneven, with a distinct reticulated network of ridges and dimples; intercarinal surfaces of V-VII finely granular, at least sparsely so. Respiratory stigmata (spiracles) of sternites IV-VI short, less than one third sternite width and crescentshaped, with distinct curve; sternite VII acarinate.

Metasoma: Length similar to that of ♀ (Tab. 2), not flattened laterally (Fig. 18B, C), intercarinal surfaces sparsely granular. Segments I-IV each with median sulcus distinct and deep; segment V with sulcus shallow, especially in posterior half; dorsosubmedian carinae obsolete; dorsolateral, ventrolateral and ventro-submedian carinae

FIG. 17

Hormurus ischnoryctes n. spec., coxae of legs II-IV, sternum, genital operculum and pectines, ventral aspect. (A) Holotype male (QM). (B) Paratype female (QM). Scale, 1.5 mm.

FIG. 18

Hormurus ischnoryctes n. spec., metasoma and telson, lateral (A, B) and ventral (C) aspect, and left tarsus IV, retrolateral (D) and ventral (E) aspect. (A) Paratype female (QM). (B-E) Holotype male (QM). Scale, 2 mm (A-C), 1 mm (D-E).

FIG. 19

Hormurus ischnoryctes n. spec., paratype male (AMNH), left hemispermatophore. (A) Dorsal aspect. (B, C) Detail of capsular region, ental (B) and ventral (C) aspect. Scale, 1 mm.

distinct on at least some segments. Segment I: Width less than or equal to height (Tab. 2); dorsomedian posterior spiniform granules weakly developed or absent; posterior spiniform granules of dorso-submedian carinae weakly developed or absent, not noticeably larger than preceding granules; lateral median carinae distinct; ventro-submedian carinae each with one or two weakly developed spiniform granules medially, one or two subposteriorly, and none posteriorly. Segment II: Dorsomedian posterior spiniform granules weakly developed or absent; posterior spiniform granules of dorsosubmedian carinae weakly developed or absent, not noticeably larger than preceding granules; ventrolateral carinae without spiniform granules; ventro-submedian carinae each with one or two spiniform granules medially, 1-3 subposteriorly, and none posteriorly. Segments III and IV: Posterior spiniform granules of dorso-submedian carinae weakly developed or absent, not noticeably larger than preceding granules; ventrolateral and ventro-submedian carinae weakly developed, sparsely granular, without spiniform granules. Segment V: Dorsal intercarinal surface sparsely granular; FIG. 20

Known localities of Hormurus ischnoryctes n. spec. in northern Queensland, Australia, with topography indicated.

dorsolateral carinae obsolete; ventrolateral carinae indistinct in anterior half, weakly developed, comprising few larger spiniform granules in posterior half; ventromedian carina weakly developed, comprising a sparse row of spiniform granules in anterior half, indistinct posteriorly; anal arch crenulate, comprising small denticles.

Telson: As long as or slightly longer than metasomal segment V (Fig. 18B); vesicle surfaces smooth.

Hemispermatophore (Fig. 19): Distal lamina curved, slightly longer than basal part; distal crest absent; well developed single laminar hook situated in basal third; basal extrusion absent; transverse ridge distinct, approximately aligned with base of laminar hook, merging with ental edge distal to laminar hook. Capsular lamella thin, folded proximally and unfolded distally to a flattened extremity (tip and base approximately the same width); longitudinal carina on dorsal surface absent to weak; accessory hook and accessory lobe absent; lamellar tip situated slightly proximal to base of laminar hook, distal to tip of distal lobe. Distal lobe well developed, not hooklike, without accessory carinae or crest, and with moderately developed, proximadoriented accessory hook on ental surface. Basal lobe well developed, spoon-shaped, merging with ental basal process; ectal edge without accessory fold, forming 135-150º angle with lamella; ental edge without accessory fold toward ectal part, forming 90º angle with lamella.

DESCRIPTION OF ADULT FEMALE: As for the Ƌ except as follows. Pedipalps: All segments slightly shorter and more robust than in male (Figs 13B, D, 15A, F, K, 16B). Dentate margins of chela fingers linear or nearly so, i.e. without pronounced lobe and notch (Fig. 16B).

FIG. 21

Habitat of Hormurus ischnoryctes n. spec. in northern Queensland, Australia. Open savanna woodland at the base of the Ngarrabullgan mesa.

Carapace: Median surface smooth or nearly so (Fig. 14B, D).

Genital operculum: Oval to semi-oval, as wide as long, approximately same width as sternum (Fig. 17B); opercular sclerites partly fused, median suture distinct; posterior notch present, at least weakly developed.

Pectines: Short, distal edge not reaching distal edge of leg IV coxa (Fig. 17B). Pectinal tooth count 7-9; teeth short and curved, sensory papillae restricted to distal part.

Mesosoma: Intercarinal surfaces of post-tergites I-VII smooth or nearly so (Fig. 14B, F); intercarinal surfaces of III-VII almost even, reticulate network of ridges and dimples obsolete.

Metasoma: Intercarinal surfaces smooth or nearly so (Fig. 18A).

INTRASPECIFIC VARIATION: Pectinal tooth counts vary from eight to ten in males, and from seven to nine in females.

DISTRIBUTION: Hormurus ischnoryctes was collected from open savanna woodlands west of Mareeba and the Atherton Tablelands in the North Queensland Highlands Province of Queensland, Australia (Fig. 20) .

ECOLOGY: Hormurus ischnoryctes was collected at the base of a large Mesozoic sandstone mesa that dominates the surrounding Queensland savanna. The Pepper Pot Sandstone, dating to the early Triassic, forms the monolithic unit of this escarpment ( Bultitude et al., 1997; Withnall et al., 1997). As with the Arnhem Plateau, this geological formation provides orographic moisture to the surrounding habitats throughout the dry months (May to October), creating a more humid microclimate along its base and slopes that supports scattered patches of mesic vine thicket. These humid habitats form a stark contrast to the surrounding semi-arid open sclerophyll woodlands (Fig. 21) and are similar in that respect to the monsoon forest patches of the Kakadu National Park, inhabited by H. longimanus. Hormurus ischnoryctes was not collected in the vine thicket patches but at the base of the mesa, in the vicinity of a perennial pool. The burrows of this fossorial species are vertical and about 15-30 cm deep, with a slit-like entrance and an enlarged terminal chamber (Fig. 38B, D). The habitat and habitus are consistent with the pelophilous ecomorphotype ( Prendini, 2001 ).

CONSERVATION STATUS: The only known population of this species is located on privately owned land where cattle farming is the dominant land-use, but in an area were grazing does not occur. However, the population appears to be at risk from other human activities. The coal basement of the geological formation that sustains the population was mined from 1910 to 1957, until this energy supply was replaced by a hydro-electric scheme. However, a major energy company recently resuscitated the exploitation of this coal deposit, and large-scale mining is expected to resume in the near future. No other populations of this species are known to occur within protected areas. Because of the restricted distribution of the only known population and the imminent threat of habitat destruction, it is recommended that H. ischnoryctes is placed on the IUCN Red List of vulnerable species (IUCN, 2001).