Hormurus ochyroscapter Monod, 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 : 327-337

Hormurus ochyroscapter Monod , n. spec. Figs 32-37

Liocheles waigiensis: Koch, 1977 (misidentification, part): 169, 171, 172.

HOLOTYPE: QM-S17072; Ƌ; Australia, Queensland, Reedybrook [18º45'S, 144º38'E]; 2.VIII.1967; excavated from hole 6 inches deep, J. D. Brown.

FIG. 32

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

FIG. 33

Hormurus ochyroscapter n. spec., carapace and mesosomal tergite I (A, B), left tarsus IV, retrolateral (C) and ventral (D) aspect, and metasoma and telson, lateral aspect (E). (A, C-E) Holotype male (QM-S17072). (B) Paratype female (QM-S17072). Scales, 2 mm (A, B, E), 1 mm (C, D).

PARATYPES: QM-S17072; 1 ♀, 2 imm.; same data as holotype .

OTHER MATERIAL: AM KS94922; 1 imm.; Almaden [17º20'S, 144º41'E], Chillagoe District ; XI-XII.1925; W. D. Campbell .

ETYMOLOGY: The name ochyroscapter is constructed from the Greek words ochyros [strong, stout] and skapter [digger]. It is an invariable noun in apposition and refers to the robust pedipalps of this species that are typical of fossorial hormurids.

DIAGNOSIS: Hormurus ochyroscapter differs from other Australian hormurids as follows. The pedipalps of H. ochyroscapter are short and robust unlike those of other Australian species, which are more elongate. The digital carina of the pedipalp chela manus is smooth (costate) and the internomedian carina obsolete in H. ochyroscapter , whereas in other species the digital carina is granular and the internomedian carina distinct and at least weakly granular. The patellar prolateral process is weakly developed in H. ochyroscapter , its two spiniform granules fused medially but not developed into a prominent median spine as in other species. Pedipalp patellar trichobothrium esb 2 is situated closer to trichobothria em 1 and em 2 than to trichobothrium esb 1 in H. ochyroscapter , whereas in other species it is situated closer to esb 1. One pair of subposterior spiniform granules and one pair of weak medial spiniform granules, present on the ventro-submedian carinae of metasomal segment III in H. ochyroscapter , are absent in other species.

MEASUREMENTS: Holotype male (QM-S17072): Total body length, 47.0. Carapace length, 6.8, anterior width, 4.8, posterior width, 7.0. Pedipalp chela length, 13.2, manus width, 4.5, manus height, 3.1; movable finger length, 6.4; patella length, 7.2, width, 3.1; femur length, 6.2, width, 2.8. Metasomal segment I length, 2.9, width, 1.9; segment V length, 4.3, width, 1.5, height, 1.4; telson vesicle width, 1.6, vesicle height, 1.9. Paratype female (QM-S17072): Carapace length, 6.7, anterior width, 4.9, posterior width, 6.7. Pedipalp chela length, 11.6, manus width, 4.6, manus height, 3.2; movable finger length, 5.8; patella length, 6.1, width, 3.0; femur length, 5.0, width, 2.4. Metasomal segment I length, 2.8, width, 1.8. (measurements for metasomal segment V and telson were not recorded because the specimen is damaged).

DESCRIPTION OF ADULT MALE: Colouration: Dorsal surface of chelicera manus yellow to pale brown; darker infuscations on fingers (Fig. 32). Carapace pale to dark brown. Pedipalps yellow to pale brown; carinae and fingers reddish brown to black. Legs pale yellow. Tergites pale to dark brown, slightly paler than carapace. Coxapophyses, sternum, genital operculum, pectines and sternites pale yellow. Metasoma yellow to pale brown. Telson yellow; 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. 33A). Anterior furcated sutures and sulci distinct. Median ocular tubercle situated anteromedially, 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, equal in size, equidistant and adjacent to one another. Postocular carapace margin aspinose. Surfaces finely granular, at least sparsely so, except anteromedially, with frontal lobes smooth and fine granulation restricted to surfaces adjacent to anterior furcated and median longitudinal sulci.

FIG. 34

Hormurus ochyroscapter 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) and prolateral (E, J, O) aspect, illustrating trichobothrial pattern. (A, F, K) Paratype female (QM-S17072). (B-E, G-J, L-O) Holotype male (QM-S17072). Scale, 2 mm.

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 short and robust (Figs 32, 34B-E, G-J, L-O, 35A), with femur length less than carapace length. Chela almost asetose. Chela fingers: Dentate margins of fixed and movable fingers linear (without lobes 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. 35A). 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 in fixed finger contiguous, no proximal gap or at most a reduced gap evident when fingers closed. Pedipalp carinae: Femur (Fig. 34L-O): Dorsoexternal carina costate, usually more distinct in proximal half; dorsointernal carina distinct, more strongly developed than dorsoexternal carina; internomedian dorsal carina absent; internomedian ventral carina vestigial, comprising two large spiniform granules situated proximally and medially on segment; ventromedian carina obsolete; ventrointernal carina distinct. Patella (Fig. 34G-J): Prolateral process distinct but weakly developed, comprising two distinct spiniform granules fused medially but not developed into a prominent median spine; internodorsal and dorsomedian carina distinct; dorsoexternal carina obsolete; externomedian carina costate-granular; ventroexternal carina distinct, costate. Chela manus (Fig. 34B-E): Dorsal secondary carina obsolete; digital carina distinct, costate, more strongly developed than external secondary carina; external secondary carina absent or obsolete; ventroexternal carina granular or crenulate; ventromedian and ventrointernal carinae obsolete; internomedian carina obsolete. Surface macrosculpture: Femur (Fig. 34L-O): Dorsal intercarinal surface densely granular except distally; retrolateral intercarinal surface at least sparsely granular dorsally, smooth or nearly so ventrally; ventral intercarinal surface granular proximally, smooth distally; prolateral intercarinal surface smooth except for a sparsely granular zone proximally. Patella (Fig. 34G-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, smooth or nearly so in distal half. Chela (Fig. 34B-E): Dorsal and retrolateral intercarinal surfaces of manus densely granular, comprising medium-sized granules; ventral intercarinal surface granular along pro- and retrolateral margins only, smooth medially; prolateral intercarinal surface sparsely granular, less so along ventral margin. 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. 34B- E, G-J, L-O). Patella: d 2 distal to patellar process; five eb trichobothria arranged in two groups, eb 1 and eb 2-5; two esb trichobothria; two em trichobothria; esb-em series arranged in two groups, esb 2 and esb 1 / em 1-2; 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 midway between Eb series and 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 eb-esb); 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.

FIG. 35

Hormurus ochyroscapter n. spec., pedipalp chela, retrolateral aspect illustrating dentate margin of chela fingers. (A) Holotype male (QM-S17072). (B) Paratype female (QM-S17072). Scale, 1 mm.

Coxosternum: Leg III coxae without swelling or bulge anterodistally. Sternum equilateral pentagonal (Fig. 36A); 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, 4-5/5 and 5/5 setiform macrosetae, respectively (Fig. 33C, D); ventromedian row of spinules reduced to few spinules basally, terminal ventromedian spinules absent; dorsomedian lobe pronounced; laterodistal lobes truncate; ungues curved, shorter than telotarsus.

FIG. 36

Hormurus ochyroscapter n. spec., coxae of legs II-IV, sternum, genital operculum and pectines, ventral aspect. (A) Holotype male (QM-S17072). (B) Paratype female (QM-S17072). Scale, 1.5 mm.

Genital operculum: Composed of two subtriangular sclerites (Fig. 36A).

Pectines: Slightly elongated, distal edge reaching and surpassing distal edge of leg IV coxa (Fig. 36A); fulcra and three marginal lamellae present. Pectinal tooth count 8-9; teeth, long, straight, entirely covered with sensory papillae.

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

Metasoma: Length similar to that of ♀, not flattened laterally (Fig. 33E), intercarinal surfaces sparsely granular. Segments I-IV each with median sulcus distinct and deep; segment V with sulcus shallow, especially in posterior half; dorso-submedian carinae absent or obsolete on all segments; dorsolateral, ventrolateral and ventro-submedian carinae distinct on at least some segments. Segment I: Width less than or equal to height; 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 carina distinct; ventrosubmedian 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 dorso-submedian 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 carinae weakly developed, comprising a sparse row of granules, without larger spiniform granules; ventro-submedian carinae weakly developed, each with one weakly developed spiniform granule medially and one subposteriorly on III, and with several larger spiniform granules posteriorly on IV. Segment V: Dorsal intercarinal surface sparsely granular; dorsolateral carinae obsolete; ventrolateral carinae indistinct in anterior half, comprising few medium-sized spiniform granules in posterior half; ventromedian carina weakly developed, indistinct posteriorly; anal arch crenulate, comprising small denticles .

Telson: As long as or slightly longer than metasomal segment V (Fig. 33E); vesicle surfaces smooth.

Hemispermatophore: Distal lamina gently curved, slightly longer than basal part; distal crest absent; 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 hook-like, without accessory

FIG. 37

Known localities of Hormurs ochyroscapter n. spec. in northern Queensland, Australia, with topography indicated.

carinae or crest, and with small proximad-oriented accessory hook on ental surface. Basal lobe well developed, spoon-shaped, merging with ental accessory lobe; ectal edge without accessory fold (no groove), 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: Dentate margins of chela fingers linear or nearly so, i.e. without pronounced lobe and notch (Figs 34A, F, K, 35B).

Carapace: Medial surfaces slightly less granular than in male (Fig. 33B).

Genital operculum: Oval to semi-oval, wider than long, approximately same width as sternum (Fig. 36B); 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. 36B). Pectinal tooth count 5-7; teeth short, curved, sensory papillae restricted to distal part.

Mesosoma: Intercarinal surfaces of post-tergites I-VII smooth or nearly so; intercarinal surfaces of III-VII even, reticulated network of ridges and dimples absent or obsolete.

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

REMARKS: Koch (1977) mentioned the short pedipalps and unusual shape of the patellar process of specimens from Almaden and Reedybrook (constituting the examined material of H. ochyroscapter ), but considered them conspecific with L. waigiensis. Only one adult male and one adult female are known. Both are severely damaged, hence certain characters (female habitus, carapace and tergite macrosculptures, metasoma of female, hemispermatophore) are not illustrated.

DISTRIBUTION: Hormurus ochyroscapter is recorded from open woodlands and savannah in the Charter Towers region and the Shire of Etheridge in Far North Queensland (Fig. 37).

ECOLOGY: Hormurus ochyroscapter was collected close to a waterbody in an inland savannah, a habitat similar to that of H. ischnoryctes . However, the climate at the type locality of H. ochyroscapter is drier than at the type locality of H. ischnoryctes , and there are no major rock formations that could potentially sustain humid conditions for extended periods. The known specimens of this fossorial species were excavated from ca 15 cm deep burrows. The habitat and habitus are consistent with the pelophilous ecomorphotype ( Prendini, 2001 ).

CONSERVATION STATUS: This species is known from only two localities situated within the boundaries of privately owned cattle stations. The type specimens were collected in 1967 and no other specimens have been collected since. The first author visited Reedybrook in 2006 to obtain more specimens, but failed to find any during several days of intensive searching. The habitat there was severely disturbed by livestock, and this population of H. ochyroscapter may be extinct. Although there are no empirical data, it appears that population densities of burrowing scorpions in different parts of the world decline in areas where large numbers of hoofed livestock are maintained, perhaps because their burrows are continuously damaged by the trampling of hooves, or due to a decrease in prey abundance and/or humidity associated with overgrazing of the vegetation (L. Monod and L. Prendini , personal observations). Based on the restricted distribution and degradation of its habitat, and despite the scarcity of data available on its distribution, ecology and abundance, it is recommended that H. ochyroscapter be placed on the IUCN Red List of endangered species (IUCN, 2001).