Paruroctonus soda, Jain & Forbes & Esposito, 2022

Jain, Prakrit, Forbes, Harper & Esposito, Lauren A., 2022, Two new alkali-sink specialist species of Paruroctonus Werner 1934 (Scorpiones, Vaejovidae) from central California, ZooKeys 1117, pp. 139-188 : 139

Paruroctonus soda sp. nov.

Figs 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14

Type material.

Holotype: USA • 1 ♂; California, San Luis Obispo County, southern tip of North Basin of Soda Lake; 35.2038, -119.8553; 585 m a.s.l.; 30 May 2021; collector leg Harper Forbes, Prakrit Jain; collected at night using handheld UV light; CASENT 9101932.

Paratypes. USA • 1♂, 2♀; same data as for holotype; CASENT 9101933 • 1♂, 2♀; California, San Luis Obispo County, northeastern edge of North Soda Lake Plain; 35.2476, -119.8630; 587 m a.s.l.; 30 May 2021; collector leg Harper Forbes, Prakrit Jain; collected at night using handheld UV light; CASENT 9101934 • 1♂; California, San Luis Obispo County, western edge of North Basin of Soda Lake; 35.2186, -119.8958; 580 m a.s.l.; 30 May 2021; collector leg Harper Forbes, Prakrit Jain; collected at night using handheld UV light; CASENT 9101935.

Additional material examined.

USA • 1 ♀; California, San Luis Obispo County, eastern edge of North Basin of Soda Lake ; 35.2263, -119.8548; 586 m a.s.l.; 30 May 2021; collector leg Harper Forbes, Prakrit Jain; collected at night using handheld UV light . • 2 ♂, 4♀; California, San Luis Obispo County, southern tip of North Basin of Soda Lake ; 35.2038, -119.8553; 585 m a.s.l.; 30 May 2021; collector leg Harper Forbes, Prakrit Jain; collected at night using handheld UV light . • 1♂; California, San Luis Obispo County, northeastern edge of North Soda Lake Plain ; 35.2476, -119.8630; 587 m a.s.l.; 30 May 2021; collector leg Harper Forbes, Prakrit Jain; collected at night using handheld UV light . • 7♂; California, San Luis Obispo County, western edge of North Basin of Soda Lake ; 35.2186, -119.8958; 580 m a.s.l.; 30 May 2021; collector leg Harper Forbes, Prakrit Jain; collected at night using handheld UV light .

Diagnosis.

Differs significantly from other Paruroctonus species found in the San Joaquin Valley and its surrounding mountains (the Inner Southern Coast Range, the Sierra Nevada, the Tehachapis, and the northern mountains of the Transverse Range) by a combination of the following characteristics: 1: Fuscous markings entirely absent from the metasoma and the posterior margin of the tergites (Figs 1 , 2 ). 2: Chelal fingers deeply scalloped in adult males, leaving a large proximal gap when closed. 3: Metasomal macrosetae along dorsolateral, ventrolateral, and ventral submedian carinae of segments I-IV follow the patterns 0,0,0,1; 1-2,2,2,2-3; and 1-2,2,2,2, respectively (Fig. 9 ). 4: All macrosetae on the manus greatly reduced in size; dorsal median, retrolateral median, ventral prosubmedian, prolateral ventral, and prolateral median carinae lacking any macrosetae except those at the proximal extent of their respective carinae (Fig. 6 ). 5: No large medial or distal retrolateral macrosetae on the pedipalp patella. 6: Length / Width ratios of metasomal segment V in adult males 2.22-2.59 and in adult females 2.21-2.28. 7: Chela length / Manus width and Chela length / Manus thickness ratios 2.05-2.16 and 2.96-3.14 in adult males, respectively and 2.15-2.30 and 2.98-3.14 in adult females, respectively.

Comparisons.

Comparisons are provided against other Paruroctonus sp. scorpions found in the San Joaquin Valley and its surrounding ranges, ordered ascendingly by the distance of the nearest record to the distribution of P. soda sp. nov. No Paruroctonus has been recorded within 13 kilometers of P. soda sp. nov., and while this distance could decrease significantly with more sampling, the habitat of P. soda sp. nov. is sufficiently distinct from that of any other nearby Paruroctonus that we consider sympatry to be unlikely.

Paruroctonus variabilis Hjelle, 1982 differs from P. soda sp. nov. in the following characters relating to the numeration in the above diagnosis: (2) Chelal fingers not scalloped (straight), leaving a negligible proximal gap when closed. (3) Metasomal macrosetae along dorsolateral, ventrolateral and ventral submedian carinae on segments I-IV follow the patterns 0,1,1,2; 3,3-5,4-5,5-6; and 3-4,4,4-5,4-8, respectively. (4) Many large macrosetae on the manus; macrosetae along chelal dorsal median, retrolateral median, ventral prosubmedian, prolateral ventral, and prolateral median carinae, excluding any near the proximal extent of their respective carinae, follow the pattern 1-3,2-4,3-4,1-2,1-2. (5) Pedipalp patella with 3-5 large medial and 2 large distal retrolateral macrosetae. (6) length/width ratios of metasomal segment V in adult males 2.85-3.02, in adult females 2.63-2.89. (7) Chela length/manus width and chela length/manus thickness ratios in adult males 2.49-3.10, 3.39-4.03, respectively, in adult females 2.90-3.37, 3.94-4.27, respectively.

Paruroctonus silvestrii differs from P. soda sp. nov. in the following characters relating to the numeration in the above diagnosis: (1) Extensive fuscousity present on the ventral surface of the metasoma, mesosomal fuscousity extending to the posterior edge of the tergites. (2) Chelal fingers not scalloped (straight), leaving a negligible gap when closed. (3) Metasomal macrosetae along dorsolateral, ventrolateral, and ventral submedian carinae on segments I-IV follow the patterns 0,1,1,2; 2,3,3,3-4; and 2-3,3,3-4,3-4, respectively. (4) Many large macrosetae on the manus; macrosetae along chelal dorsomedian, retrolateral median, ventral prosubmedian, prolateral ventral, and prolateral median carinae, excluding any near the proximal extent of their respective carinae, follow the pattern 0-1,1-2,1-2,1,1. (5) Pedipalp patella with 2-4 large medial and 2 large distal retrolateral macrosetae. (6) Length/width ratios of metasomal segment V in adult males 2.72-2.90, in adult females 2.46-2.63. (7) Chela length/manus width and chela length/manus thickness ratios in adult males 2.59-2.70 and 3.36-3.65, respectively; in adult females 2.75-3.06 and 3.73-4.15, respectively.

Paruroctonus boreus differs from P. soda sp. nov. in the following characters relating to the numeration in the above diagnosis: (1) Fuscousity present on the ventral surface of the metasoma, especially on segments II-IV. (3) Metasomal macrosetae along dorsolateral, ventrolateral and ventral submedian carinae on segments I-IV follow the patterns 0,0-1,1,1-2; 2,3,3,3-4, and 2,2,2-3,3, respectively. (4) Several large macrosetae on the manus; macrosetae along chelal dorsal median, retrolateral median, ventral prosubmedian, prolateral ventral, and prolateral median carinae, excluding any near the proximal extent of their respective carinae, follow the pattern 0,1-2,1,1,1. (5) Pedipalp patella with 1-2 large medial and 2 large distal retrolateral macrosetae. (6) Length/width ratios of metasomal segment V in adult males 2.72-3.12, in adult females 2.50-2.71.

Paruroctonus conclusus sp. nov. differs from P. soda sp. nov. in the following characters relating to the numeration in the above diagnosis: (3) Metasomal macrosetae along dorsolateral and ventral submedian carinae on segments I-IV follow the patterns 0,1,1,2 and 2,2,2,3, respectively. (4) Several large macrosetae on the manus; macrosetae along chelal dorsal median, retrolateral median, ventral prosubmedian, prolateral ventral, and prolateral median carinae, excluding any near the proximal extent of their respective carinae, follow the pattern 0,1-2,1,1,1. (5) Pedipalp patella with 1 large medial and 2 large distal retrolateral macrosetae. (6) Length/width ratios of metasomal segment V in adult males 2.86-3.05, in adult females 2.47-2.56.

Description of male holotype.

Coloration (Figs 1 - 3 ). Carapace orange-brown with faint fuscous markings present directly posterior to the median eyes, at the posterior-lateral corners of the carapace, and along the posterior edges of the interocular triangle. Tergites I-VI with fuscousity occupying the majority of the segment with the exception of the posterior and lateral margins; fuscousity somewhat reduced on VII. Legs pale cream to slightly tan. Pedipalps tan to orange with slightly darker orange carinae and dark orange fingers. Metasoma tan with faintly orangish carinae. Telson pale yellow, base of aculeus dark reddish, and aculeus black. Sternites brown, with tan spiracles. Pectines, sternum, and genital operculum tan to cream.

Carapace (Figs 4 , 5 ). Anterior margin roughly straight with three pairs of distinct macrosetae. Surface irregularly granular, with the largest granules near the center of the carapace. Very fine, evenly spaced granules present between the large granules. Lateral margins finely crenulate. Posterior median sulcus narrow and moderately deep, free of granulation. Anterior median, median ocular, lateral ocular, and posterior lateral sulci broad and shallow, entirely free of granules. Anterior and posterior marginal sulci shallow and sparsely granular. Median ocelli separated by a distance greater than the width of one ocellus. Three pairs of lateral ocelli present. Single pairs of macrosetae present posterior to the median ocelli, between the lateral ocelli and the margin of the carapace, and roughly halfway between the posterior median sulcus and the margin of the carapace, in line with the posterior edge of the ocular tubercle.

Mesosoma (Figs 2 , 3 ). Tergites I-VI very finely granular to smooth, except on the posterior and lateral thirds, which are weakly granular to granular. These areas become increasingly granular on subsequent segments. Median longitudinal carina absent on tergites I-II, indistinct and very weakly crenulate on III-VI. Submedian longitudinal sulci indistinct. One pair of small posterior sub-median setae on tergites I-VI. Tergite VII essentially smooth anteriorly and irregularly granular elsewhere. Posterior margin finely granular; lateral marginal, dorsolateral, and dorsal sub-median carinae crenulate. Median longitudinal carina indistinct. Sternites III-VI sparsely setose and smooth. Sternite VII smooth anteriorly, finely granular posteriorly, and granular laterally, with ventral submedian carinae indistinct and very weakly crenulate and lateral marginal carinae irregular and weakly crenulate.

Genital operculum (Fig. 5 ). Sclerites roughly triangular with rounded corners, wider than long. Overlapping medially and separated slightly only at the posterior edge, with protruding genital papillae. Several macrosetae present on each sclerite.

Sternum (Fig. 5 ). Type 2 with posterior emargination absent. Lateral lobes concave anteriorly, roughly straight laterally, convex posteriorly. Apex deep. Sclerite slightly wider than long, smooth to finely granular, especially along the slopes of the apex. Three pairs of macrosetae.

Pectines (Fig. 5 ). Long, thin, and densely hirsute, with 21/21 tightly packed teeth on each side. Middle lamellae roughly circular distally, highly irregular in size and shape proximally; roughly 16/15 distinct and separated sclerotized sections are visible under ultraviolet illumination.

Legs. Carinae. Retroventral carinae on Leg I femur unpigmented and finely crenulate; proventral carinae sparsely, finely and weakly crenulate on Leg I patella. Both decreasingly distinct on subsequent legs, proventral carinae on patella absent by leg IV. Other carinae indistinct to absent on all legs. On all legs, femur irregularly and very finely granular; other surfaces smooth.

Telotarsi . Telotarsal retroinferior terminal macrosetae on legs I-IV 1/2, 2/2, 2/2, 2/2; other telotarsal retroinferior macrosetae on the distal half of telotarsi I-IV 1/1, 1/1, 1/1, 2/2. Two telotarsal retromedial macrosetae on each leg, with one always at the retromedial terminal position. Two large telotarsal retrosuperior macrosetae on each leg with consistent positions, with an additional smaller retrosuperior seta on dextral leg III. Single proinferior terminal macroseta on each leg except two on dextral leg II. Single proinferior distal macroseta on each leg, single other proinferior macroseta on legs II-IV except none on sinistral leg III. Two telotarsal promedial macrosetae on legs I-III at terminal and distal positions; one on leg IV in the terminal position. Two large telotarsal prosuperior macrosetae on each leg in terminal and medial positions. Single telotarsal superioterminal and superior macroseta present on all legs.

Basitarsi . Three basitarsal spine rows present on legs I and II; proventral and retroventral spine rows equally dense and retrosuperior spine row less dense. The retroventral spine row extends ca. two-thirds the entire length of the segment, the proventral spine row extends through ca. half the segment, and the retrosuperior spine row extends through less than half. On leg III, proventral spine row absent and the retroventral and retrosuperior spine rows heavily reduced both in size and density. On leg IV, both the proventral and retroventral spine rows are absent and the retrosuperior spine row is heavily reduced in size and density, almost absent. Basitarsal retroventral macrosetae on legs I-IV, excluding only the distal retroventral spinoid macroseta at the end of the retroventral spine row, follow the pattern 2/3, 5/5, 4/5, 5/4, with variable sizes. Spinoid basitarsal proventral macrosetae on legs I-IV follow the pattern 2, 2, 3, 3; an additional thinner distal ventral macroseta is present on legs II-IV. Superior basitarsal macrosetae on legs I-IV consist of two spinoid macrosetae at the distal and mid retrosuperior positions; one macroseta at the distal prosuperior position; one macroseta at the distal superiomedian position adjacent to the distal retrosuperior macroseta, except on sinistral leg IV and dextral legs II-IV; and large superiomedian macrosetae following the pattern 4/4, 5/5, 5/5, 4/4. Prolateral macrosetae on legs I-IV, excluding one on the margin, follow the pattern 3/3, 3/3, 2/3, 2/2.

Pedipalps (Figs 6 - 8 ). Femur. Dorsal prolateral carina crenulate with two macrosetae on the proximal half; dorsal retrolateral carina also crenulate with two macrosetae on the proximal three-fourths. Dorsal surface sparsely granular. Retrolateral dorsosubmedian carina weakly crenulate; retrolateral surface otherwise smooth aside from a few proximal granules. Two long median macrosetae on the retrolateral surface. One large inframedian macroseta on the distal fourth of the retrolateral surface. Ventral retrosubmedian carina vestigial, irregularly granular with granules decreasing in size distally. Prolateral surface granular with two prolateral ventral macrosetae on the proximal half, one prolateral ventrosubmedian macroseta at the midpoint, and a pair of macrosetae on the distal margin.

Patella . Dorsal retrolateral carina weakly crenulate with a large proximal macroseta; dorsal prolateral carinae crenulate with a small proximal macroseta. Dorsal surface essentially smooth. Retrolateral median carinae indistinct and very weakly crenulate, retrolateral surface otherwise smooth. Two very small and indistinct retrolateral distal marginal macrosetae present. Ventral retrolateral carina weakly crenulate; ventral prolateral and ventral median carinae crenulate. Ventral surface smooth. Prolateral median carina indistinct to absent, represented by a few large granules. Prolateral surface sparsely and weakly granular. Prolateral surface with large proximal supramedian, proximal inframedian, and distal inframedian macrosetae; heavily reduced distal supramedian macroseta. No large macrosetae present on the ventral and external surfaces.

Chela . Dorsal prolateral carina indistinct, non-linear, and crenulate with no macrosetae, smooth on the fixed finger. Dorsal median carina weakly crenulate proximally and smooth distally, stopping at the base of the fixed finger, with a single small macroseta at its proximal extent. Dorsal retrosubmedian carina vestigial, consisting of only a few weak granules, and extending through less than the proximal fifth of the manus. Dorsal retrosubmedian accessory carina weakly crenulate, extending through less than the proximal fifth of the manus, with a small proximal macroseta. Dorsal retrolateral carina very weakly crenulate proximally and smooth distally, entirely smooth on the fixed finger, with a small distal macroseta near the base of the fixed finger. Retrolateral median carina very weakly granular and unpigmented, lacking setation. Ventral retrolateral carina indistinct and weakly crenulate, with 0/1 small macrosetae at its proximal extent. Intercarinal spaces on the dorsal and retrolateral surfaces smooth. Ventral prosubmedian carina indistinct and very weakly crenulate, with a single small macroseta at its proximal extent. Ventral surface smooth to granular near the base of the movable finger. Prolateral ventral and median carinae both crenulate to weakly crenulate with a single small macroseta at their respective proximal extents. Two additional small carinae are present near the base of the fixed finger, both of which are evenly and finely crenulate. Prolateral surface of the manus otherwise mostly smooth with some weak and irregular granulation in the distal half. The fingers are heavily scalloped, leaving a large proximal gap when closed. The chela is uniformly finely granular at the base of this gap. Retrolaterally, the fingers are smooth except some fine proximal granulation. Prolaterally, the fingers are smooth aside from a few patches of granulation on the proximal half. 19/16 small macrosetae and numerous microsetae are present on the ventral surface of the movable finger. No movable finger ventral prolateral, fixed finger prolateral median, or fixed finger prolateral dorsolateral macrosetae are present. The movable finger has one proximal prolateral median macroseta. A single proximal retrolateral median macroseta is present on the movable finger and a single dorsal prolateral seta is present near the distal end of the fixed finger. Both the fixed and movable fingers have five enlarged denticles dividing the primary denticles into six sub-rows, with an additional enlarged denticle at the distal extent of the movable finger, alongside the distal hook. On the fixed finger, rows I-VI contain 5/5, 7/6, 7/7, 7/8, 10/9, 12/10 primary denticles with a total row I-V count of 36/35. On the movable finger, rows I-VI contain 6/6, 8/8, 10/9, 9/10, 13/13, 9/10 primary denticles with a total row I-V count of 46/46. Each enlarged denticle as well as the distal finger-tip hook is accompanied by a single prolateral supernumerary denticle, for a total of six on the fixed finger and seven on the movable finger. There is a single macroseta posterior to each supernumerary denticle apart from the two most distal ones on each finger for a total of four on the fixed finger and five on the movable finger. Two further macrosetae are present near the proximal primary denticle row on the fixed finger.

Metasoma (Fig. 9 ). Dorsal surface I-V smooth with a few scattered granules. Dorsolateral carinae on segments I-IV strongly crenulate to serrate, weakly crenulate on V. Lateral supramedian surface smooth with a few scattered granules. Lateral supramedian carinae I-IV crenulate. Lateral surface smooth. Lateral inframedian carinae crenulate on I-III, extend through only the posterior fifth of segments II-III. Lateral median carinae weakly crenulate on V, extending ca. a third of the way up the segment. Ventrolateral carinae I-IV smooth to weakly crenulate, becoming weakly crenulate on the posterior fourth of each segment. Ventrolateral carinae on segment V strongly crenulate to serrate. Ventral surface of segment I-IV smooth; ventral surface granular on segment V. Ventral sub-median carinae on I-IV smooth, unpigmented, and indistinct. Ventromedian carinae on segment V are crenulate, irregular, and disconnected. Dorsolateral macrosetae I-V follow the pattern 0,0,0,1,2. Lateral supramedian macrosetae I-IV follow the pattern 0,1,1,1. One Lateral median macroseta on V. Lateral inframedian macrosetae I-III follow the pattern 1,0,0. Ventrolateral macrosetae I-V, excluding any on the posterior margin of the segment, follow the pattern 1,2,2,2,3/4. Ventral submedian macrosetae I-IV, excluding those on the posterior margin of the segment, follow the pattern 1,2,2,2. Three pairs of macrosetae are present between the ventromedian and ventrolateral carinae on segment V. Two pairs of macrosetae on the ventral posterior margin of metasomal segment V; a single pair of macrosetae on the ventral posterior margins of other metasomal segment.

Telson (Fig. 9 ). Very weakly granular on the ventral anterior portion, otherwise smooth. Sparsely setose ventrally and laterally.

Hemispermatophore (Fig. 10 ). Hemispermatophore roughly equal in width from pedicel to stalk, three fold bauplan ( Monod et al. 2017). Stalk wide and relatively straight and dorso-ventrally flattened. Distal carina and lamelar hook scletertized, lamelar hook bifurcate at terminus. Mating plug weakly scleretized, moderate in size with a wide bilobed base and relatively long stem terminating in a barb.

Female. Larger size. Relatively thinner chela with less curved fingers, weakly scalloped with a negligible gap when closed. Most proximal row on the chelal fixed finger with 16-21 primary denticles; most proximal row on the chelal movable finger with 10-13 primary denticles. Metasoma more robust. Pectines smaller overall with smaller teeth; teeth count 17-19 (17 n = 4.5, 18 n = 1.5, 19 n = 1) and middle lamella count 12-15 on a side. Sclerites separated narrowly through their entire length with the gap slowly increasing toward the posterior half.

Variation. Coloration (Figs 1 - 3 ). Fuscous markings posterior to the median eyes and in the posterior-lateral corners of the carapace range from typically prominent to sometimes indistinct to absent. Those along the edges of the interocular triangle are typically faint but range to absent. Fuscous markings on tergites I-VI also highly variable, ranging in extensiveness from covering the entire tergite except the posterior and lateral margins to covering only a small area around the anterior half of the submedian sulci. Fuscous markings on tergite VII also variable, ranging from covering approximately the anterior three-fourths of the segment to only being present in small areas along the dorsal submedian carinae. Other aspects of coloration in preserved specimens relatively consistent. In life, carapace, metasoma, and pedipalp coloration ranges from dark brown to tan, but is typically orange.

Carapace (Figs 4 , 5 ). Level and density of granulation variable. The elevated area of the interocular crescent on either side of the anterior median sulcus is sometimes largely free of granulation.

Tergites (Fig. 2 ). Posterior granulation on tergites I-VI ranging from weakly granular through the posterior third of the segment to indistinct, very weakly granular, and restricted to the posterior margin of the segment. Lateral granulation sometimes absent.

Pectines (Fig. 5 ). Pectines in males 21-24 (21 n = 2.5, 22 n = 5, 23 n = 5.5, 24 n = 2) with 15-20 middle lamellae per side.

Legs. Retroventral carinae on the leg patella ranging from finely crenulate to very weakly crenulate, almost absent. Prosuperior carinae on the leg femur ranging from very finely crenulate to weakly finely crenulate, almost absent. Retroventral spine row on basitarsus III ranging from equal in length and density to retrosuperior spine row to indistinct, almost absent. Terminal retroinferior macrosetae on telotarsus II 1-2, other retroinferior macrosetae on telotarsus III 1-2, retromedian macrosetae on telotarsus IV 2-3. Additional small retrosuperior macrosetae present occasionally on legs II-III. Other large telotarsal retrolateral macrosetae described in the holotype description consistent with the exception of occasional asymmetrical additions or deletions. Second promedian macroseta occasionally present on leg IV and third promedian macroseta occasionally present on leg I; other large telotarsal prolateral macrosetae described in the holotype description consistent with the exception of occasional asymmetrical additions or deletions. Number of retroventral basitarsal setae on legs I-IV highly variable, within the following ranges for legs I-IV: 3-4, 5-6, 5-6, 5-6 with occasional asymmetrically added or missing setae. Proventral basitarsal macrosetae consistent. Large superior basitarsal macrosetae on legs I-IV, excluding the large spinoid distal and mid retrosuperior macrosetae; the large distal prosuperior and sometimes present small medial prolateral macrosetae; and the often absent macroseta at the distal superiomedian position adjacent to the distal retrosuperior macroseta, are highly variable, within the ranges 4-5, 5-6, 5-6, 4-5 with occasional asymmetrical deletions or additions of small macrosetae. Prolateral macrosetae on legs I-IV, excluding one on the margin, highly variable and often non-linear, within the ranges 3, 2-4, 2-4, 2-4 with occasional asymmetrical deletions. The smaller distal superiomedian macroseta is often missing on any leg.

Pedipalps (Figs 6 - 8 ). Macrosetae on femur variable: prolateral ventrosubmedian sometimes missing; retrolateral dorsosubmedian excluding those on distal margin 2-4; other occasional asymmetrical deletions. Proximal macroseta on the pedipalp patella dorsal prolateral carina small or large, other large macrosetae on patella consistent. Patella retrolateral median carina weakly crenulate to very weakly crenulate with an inconsistent pattern. Two very small and indistinct distal median macrosetae sometimes present on the external surface of the pedipalp patella; no large medial or distal macrosetae ever present on the external surface of the pedipalp patella. On the chela, a small median macroseta on the dorsal prolateral carina and the ventral retrolateral carina sometimes present. A small proximal macroseta on the ventral retrolateral carina and a small macroseta along the dorsal retrolateral carina near the base of the fixed finger sometimes absent. On the fixed finger, prolateral median macroseta rarely present. Ventral macrosetae on the movable finger 15-19. Number of primary denticles in rows I-V on the fixed finger within the ranges 3-6, 5-7, 6-8, 7-9, 9-12. Number of primary denticle in row VI on the fixed finger of males 9-14. Number of primary denticles in rows I-VI on the movable finger within the ranges 4-7, 6-9, 8-10, 10-12, 11-17. Number of primary denticle in row VI on the movable finger of males 8-10. Primary denticles on the fixed finger excluding those on the proximal row 30-38 and primary denticles on movable finger excluding those on the proximal row 42-50 with no obvious sexual dimorphism in either.

Metasoma (Fig. 9 ). Crenulation on metasomal ventrolateral carinae variable, ranging from very weakly crenulate on the posterior third to weakly crenulate on the posterior half. Lateral inframedian carina on II-III from ca. one fifth to one third the length of the segment. Dorsolateral medial macroseta on V ranging from indistinct to absent to small but distinct for a total of 2-3 macrosetae. Ventrolateral macrosetae on I 1-2, ventral submedian macrosetae on I 1-2, ventrolateral macrosetae on IV 2-3, ventrolateral macrosetae on V 3-6, and lateral supramedian macrosetae on IV 1-2. Other metasomal setae are consistent with the exception of occasional asymmetrical deletions.

Remarks.

The most valuable taxonomic characters for P. soda sp. nov. are:

The macrosetal patterns on the pedipalps and metasoma are very consistent and unique, provide excellent diagnostics against almost all other Paruroctonus .

The morphometric ratios of different aspects of the metasomal segments and chela are fairly consistent and do not overlap with those of several other Paruroctonus .

The lack of fuscous markings on the metasoma and chelae is very consistent and provides a helpful diagnostic for comparison with several other Paruroctonus .

The overall color pattern and the fuscous patterning on the carapace and tergites is somewhat variable but is still a reliable diagnostic character.

Other taxonomic characters which may be taxonomically valuable in some cases, but are typically not useful, include:

The telotarsal macrosetae are somewhat variable but have different counts than those of certain other Paruroctonus .

The extent of granulation on the carapace and tergites is fairly variable but is notably different from certain other Paruroctonus . This character, however, can be difficult to quantify.

The basitarsal macrosetae are generally extremely variable and are only helpful for differentiating P. soda sp. nov. from psammophilous Paruroctonus . The basitarsal spinoid distal and mid retrosuperior macrosetae are not variable but are still only helpful for differentiating P. soda sp. nov. from these psammophiles.

The granulation on the pedipalps, legs, and metasoma is somewhat variable and difficult to quantify. It is fairly similar to that of most other Paruroctonus species, although in isolated examples may be used for diagnosis.

The pectinal tooth counts are somewhat variable and are only useful as a diagnostic against some other Paruroctonus . Middle lamellae counts are also not taxonomically valuable, as they are typically ambiguous.

The chelal primary denticle counts are somewhat variable and overlap with those of most other Paruroctonus .

Habitat, distribution, and ecological notes.

Paruroctonus soda sp. nov. is known only from the area immediately surrounding Soda Lake in the Carrizo Plain, an area of the San Joaquin Valley in San Luis Obispo county, California (Fig. 11 ). Soda Lake is a complex of a single large and dozens of smaller typically dry lake beds draining the Carrizo Plain and its surrounding ranges, an endorheic watershed ca. 1230 km2 in size ( Stephenson 2013). The lake complex began to form during the Pliocene epoch when tectonic activity severed a connection to the ocean ( Cooper 1990; Stephenson 2013). A permanent, deep, brackish lake persisted from ca. 75 kya to around 16-17 kya, at which point a drying climate and hotter temperatures led to the lake shrinking and increasing in alkalinity ( Stephenson 2013). The habitat surrounding the lake is now an alkali sink largely dominated by Atriplex spinifera , Atriplex vallicola , Allenrolfea occidentalis , and various small wildflower and grass species ( Munz and Keck 1949; Buck-Diaz et al. 2013 Stout et al. 2013).

The Carrizo Plain receives approximately 230 mm of sporadic winter rain in an average year resulting in an arid climate. Water drainage from the surrounding Temblor, La Panza, and Caliente ranges, which receive a slightly greater amount of rainfall, keeps the Soda Lake complex and the immediately surrounding area comparatively moist ( Stephenson 2013). The summer climate in the region is hot and arid, with little to no rainfall and temperatures typically in excess of 35 °C during the hottest months.

Along the western, southwestern, and eastern edges of the largest basin (North Basin), we found Paruroctonus soda sp. nov. to be present only in a thin band of soft clay soil dominated by Allenrolfea occidentalis immediately adjacent to the edge of the dry lakebed (Figs 11 , 12 ). To the northeast of the North Basin is a relatively large area of soft clay soils including a multitude of smaller basins (North Soda Lake Plain). Specimens of Paruroctonus soda sp. nov. were collected at the point in the North Soda Lake Plain region furthest from the edge of the North Basin, suggesting that it is likely found throughout a significant portion of the North Soda Lake Plain. Paruroctonus soda sp. nov. was not found along the edge of the second-largest basin (South Basin) and the smaller basin immediately to its north despite significant sampling. We hypothesize that Paruroctonus soda sp. nov. is absent from these basins because the band of soft clay soil surrounding these basins is too narrow to support a population of this species. It is, however, impossible to make high-confidence conclusions of absence from a single night of sampling. Paruroctonus soda sp. nov. was also not found in any of the areas of relatively tougher soil dominated by Atriplex polycarpa or A. spinifera . We hypothesize that this species’ reliance on soft clay soils may be due to the high summer surface temperatures in the area, as the softer soils form deep cracks and are relatively easier to burrow into.

No scorpions were found in sympatry with Paruroctonus soda sp. nov. However, the presence of Hadrurus obscurus Williams, 1970 and Paravaejovis sp. is possible, as both species have records from the Panorama Hills a few kilometers from Soda Lake and the latter has records a short distance to the north of the North Basin. The geographically closest Paruroctonus is P. variabilis , found in the nearby Panorama Hills and Temblor range. However, we consider it unlikely that P. variabilis is found in the flat portion of the Carrizo Plain near Soda Lake as we have been unable to locate any after significant sampling.

All specimens included in the description of this species were found by blacklight on 30 May 2021 and additional specimens were found by users of iNaturalist.org on 19 May 2021 and 1 March 2022. Paruroctonus soda sp. nov. was abundant at all localities where it was found. We found a higher density of surface-active adult males than surface-active adult females, and a higher density of surface-active adults than surface-active juveniles. A single late-instar juvenile female Paruroctonus soda sp. nov. was found to be whitish in color and completely lacked fuscousity (Fig. 13 ), possibly indicating hypomelanism. It is unclear whether this was a low-probability chance event or if there is a significant portion of the population of Paruroctonus soda sp. nov. with this trait. A gravid adult female collected and maintained alive in captivity gave birth in mid-August to 51 offspring, of which all except one survived until the first molt (Fig. 14 ).

Conservation.

Fortunately, the entirety of the range of Paruroctonus soda sp. nov. is encompassed within the Carrizo Plain National Monument, rendering the species safe from the primary anthropogenic threats to scorpions: land alteration and habitat destruction due to human development.

Etymology.

Paruroctonus soda sp. nov. is named after Soda Lake, which is the only locality this species is known from. The name also reflects the highly alkaline soils this species inhabits.

Figures

Figure 1. Variation of Paruroctonus soda sp. nov. from across their range. Top two rows, males; bottom row females; holotype male top left.

Figure 2. Dorsal habitus photographs of Paruroctonus soda sp. nov. holotype male (left) and female (right). Scale bars: 10 mm, silhouettes to scale.

Figure 3. Ventral habitus photographs of Paruroctonus soda sp. nov. holotype male (left) and female (right). Scale bars: 10 mm, silhouettes to scale.

Figure 4. Carapace of Paruroctonus soda sp. nov. holotype male (left) and paratype female (right). Scale bars: 5 mm.

Figure 5. Carapace (upper) and sternopectinal region (lower) of Paruroctonus soda sp. nov. holotype male (left) and female (right). Taken under ultraviolet illumination. Scale bars: 5 mm.

Figure 6. Pedipalp of Paruroctonus soda sp. nov., holotype male (above) and female (below). Macrosetae indicated with open circles (proximal) and closed circles (diagnosis character 4). Carinae abbreviations: retrolateral median (rm), dorsal retrolateral (drl), dorsal median (dm), dorsal prolateral (dpl), ventral retrolateral (vrl), ventral prosubmedian (vps), prolateral ventral (plv), prolateral median (plm). Scale bars: 10 mm.

Figure 7. Illustrations of pedipalp chela of Paruroctonus soda sp. nov. A-D holotype male and E-H female A, E retrolateral B, F prolateral C, G dorsal D, H ventral. Trichobothria indicated with open circles. Scale bars: 5 mm.

Figure 8. Illustrations of pedipalp patella and femur of Paruroctonus soda sp. nov. holotype male (B, C) paratype female (A, D). A dorsal patella B retrolateral patella C ventral patella D dorsal femur. Trichobothria indicated with open circles. Scale bars: 2 mm.

Figure 9. Metasoma of Paruroctonus soda sp. nov. holotype male (above) and female (below); ventral, lateral, and dorsal aspects (top to bottom). Ventral sub-median, ventrolateral, lateral submedian, and dorsolateral macrosetae on segments I-IV indicated with black circles (diagnosis character 3). Carinae abbreviations: Dorsolateral (dl), lateral median (lm), lateral supramedian (lsm), lateral inframedian (lim), ventrolateral (vm), ventral submedian (vs), and ventromedian (vm). Scale bars: 10 mm.

Figure 10. Right hemispermatophore of Paruroctonus soda sp. nov.: anterior aspect (left) and posterior aspect (right). Scale bar: 5 mm.

Figure 11. Soda Lake and the surrounding Carrizo Plain, the type locality of Paruroctonus soda sp. nov. Above, satellite imagery of the central Carrizo Plain taken in June 2019; below, a regional overview taken from the eastern side of the North Basin and facing southwest across the Soda Lake taken in May 2021.

Figure 12. Habitat of Paruroctonus soda sp. nov. in May 2021. Note the dominance of Allenrolfea occidentalis and the soft, exposed clay soil along the lakebed.

Figure 13. Photographs of a typical juvenile Paruroctonus soda sp. nov. (left), and atypical coloration observed in one late instar juvenile female. Not to scale.

Figure 14. Adult female Paruroctonus soda sp. nov. with 51 newly born juveniles.