Paruroctonus, Werner

Mcwest, Kari J., 2009, Tarsal spinules and setae of vaejovid scorpions (Scorpiones: Vaejovidae), Zootaxa 2001, pp. 1-126 : 21-25

Genus PARUROCTONUS Werner

n = 10/29

The genus Paruroctonus comprises three species groups (infragroups) proposed by Haradon (1984a, 1984b, 1985) and named after the following species: gracilior , boreus , and stahnkei .

Setal arrangements were discussed by Haradon and my findings generally did not differ from his. The basitarsal and telotarsal series of Paruroctonus boquillas were briefly discussed by Sissom & Henson (1998) but the full setal complements are illustrated here for the first time. Members of Paruroctonus generally lack ventral spinules on basitarsus III.

Haradon developed a formula for the basitarsus superior setal series for Paruroctonus species in which the setae were reported in two counts, distal row + proximal row, or as a single count for irregular or single-file arrangements (1984a: 205), essentially where there is no readily visible means of separating the two rows. Where applicable, the Haradon arrangements are included in the accounts. Typically, Paruroctonus species possess a single superior apical seta on the telotarsus.

The following accounts are arranged by infragroup and microgroup after Sissom (2000). Basitarsus III setal counts were supplemented by Haradon’s revision for species that were not examined in this study. Telotarsal counts were not supplemented by data from Haradon’s revision because counts of the proinferior terminal setae were not included in his reports. Differences among the groups and species are noted in the surfaces. The setal series have 5–10 superiors, typically 1 retrosuperior (lacking only in P. arenicola nudipes ), 3–6 retroventrals, and 3 ventrals. The superior, landmarks, and retroventral series are often supplemented with minor setae. Spinule counts range 4–30 retrosuperiors, 0–43 retroventrals, and 0–3 ventrals.

Telotarsus: The total telotarsal setal complement in Paruroctonus ranges 9–19 (mode = 16); 1–2 retroinferiors, 0–2 retromedials (mode = 1; only some P. boreus had 2), 1–3 retrosuperiors (mode = 2; only P. boquillas with 3), 0–2 retrosuperior terminals (mode = 1; stahnkei infragroup with 0), 1–2 proinferior terminals (mode = 1; only P. boquillas and P. pecos with 2), 0–2 promedials (mode = 1), 0–2 prosuperiors (mode = 1; only P. boreus “topotype” with none), and 0–3 prosuperior terminals (mode = 1; baergi group with 2–3). Typically there are 2 distal spinules (mean = 2.06; variance = 0.10; sd = 0.32), 5–11 ventromedians (mean = 7.75; var = 2.38; sd = 1.54), and 3–13 basals (mean = 6.65; variance = 3.67; sd = 1.92).

I. gracilior infragroup

n = 1/1

This monotypic infragroup includes the type species of the genus. Throughout its distribution, its habitat is chiefly associated with compacted, consolidated sand or gravel on “desert pavement”. Although there are several populations associated with dune environments in northern Mexico that were previously assigned to P. pallidus ( Haradon 1985) , specimens from sandy habitats were not examined .

Basitarsus: The basitarsus of examined Paruroctonus gracilior (Hoffmann) distinctly have 2 retrosuperior setae, the proximal of which was included in the superior series by Haradon (1985: 22), but is distinctly angled retrad and in line with the retrosuperior carina. Notable differences in basitarsus III compared to other paruroctonoids (except Paravaejovis ) are the possession of 1 distal retroventral seta (as does Paravaejovis ), fewer than 6 total spinules on the retrosuperior, retroventral, and ventral carinae (instead of 19–84), the lack of retroventral spinules (instead of 8–67). It differs from Paravaejovis in possessing 3–4 superior setae (compared to 6) and 1 distal ventral seta. Only certain members of the P. boreus microgroup have as few as 5 superior setae.

Telotarsus: Paruroctonus gracilior differs from most other paruroctonoids in having fewer than 15 total telotarsal setae, which it shares with Paravaejovis and certain members of the P. stahnkei infragroup. It differs from Paravaejovis and the P. baergi microgroup in having 1 retrosuperior seta (instead of 2–3). Paruroctonus gracilior shares the lack of promedial setae with some members of the P. stahnkei infragroup. There are 2 prosuperior setae, shared with P. stahnkei ; other paruroctonoids usually possess only 1, or the distalmost setae are located on the superoterminal lobe. On P. gracilior , I interpret this as the absence of superior terminal setae on the superoterminal lobe; the rst and pst are positioned at their respective junctions of the telotarsal cylinder with the superoterminal lobe.

Paruroctonus gracilior (Hoffmann)

( Figs. 20–24)

Basitarsus: Setae (19–20): S, 3–4; DSM, 1; DPS, 1; DRS, 2; RS, 2; RV, 5; DRV, 1; V, 3; DV, 1. Spinules (4): RS, 4; RV, 0; V, 0.

Telotarsus: Setae (13–14): ri, 0–1; rid, 1; rit, 1; rm, 1; rmt, 1; rs, 1; rst, 1; pi, 1; pid, 1; pit, 1; pm, 0; pmt, 1; ps, 1; pst, 1; sa, 1. Spinules (11–15: mean = 13.82; var = 1.56; sd = 1.25): ds, 2; vms, 6–8 (mean = 7.12; var = 0.57; sd = 0.76); bs, 3–7 (mean = 4.71; var = 1.03; sd = 1.02).

Specimens examined: TEXAS: Brewster County: 5 mi E Lajitas, 3 f, 10 m ( WDS); Culberson County : 16 mi N Kent, 1 f, 3 m ( WDS) .

II. boreus infragroup

The boreus infragroup includes four microgroups named after the following species of Paruroctonus ( Haradon 1984a) : boreus , becki , baergi , and xanthus (the latter was not examined, and has 6–7 retrosuperior setae on telotarsus III [ Haradon, 1984a: 210]). The superior terminal setae are usually located on the superoterminal lobe of the telotarsus.

Basitarsus: The boreus group has 19–27 setae on the examined surfaces: S, 5–10; distal lms, 3–5; RS

Telotarsus: Total setal complement ranges 15–19 (16): ri, 1 (0–1 in P. silvestrii ); rid, 1; rit, 1–2 (1 in P. boquillas and in P. becki ); rm, 0–2; rmt, 1; rs, 1–3; rst, 1–2; pi, 1; pid, 1; pit, 1–2; pm, 1– 2; pmt, 1 (0 in P. baergi ); ps, 0–1; pst, 1–3. Spinule series: d s 2 (rarely 3–4 in P. silvestrii ); vms 5–11; bs 4–12.

II.1. boreus microgroup

n = 2/6

Basitarsus: Members of the boreus microgroup examined have 19–21 setae on the examined surfaces: S, 5–6; distal lms, 3–4; RS (MRS), 1; RV, 3–5; DRV, 2; V, 3; DV, 1. RS spinules, 10–30; RV spinules, 8–43; V spinules, 0–3. For comparisons with the gracilior infragroup, see that section. Differs from baergi and becki microgroups in having fewer setae ( boreus with 19–21, baergi with 23–27, becki with 24), with primarily fewer superiors ( boreus with 5–6, baergi with 8–10, becki with 6) and retroventrals ( boreus with 3–5, baergi with 5 9, becki with 6). Differs further from becki microgroup in having a single major prosuperior lms whereas becki has 2.

Telotarsus: Total setal complement ranges 15–16: ri, 0–1; rid, 1; rit, 1–2; rm, 1–2; rmt, 1; rs, 1–2; rst, 1–2; pi, 1; pid, 1; pit, 1; pm, 1–2; pmt, 1; ps, 0–1; pst, 1–2. Spinule series: d s 2 (rarely 3, 4 in P. silvestrii ); vms, 5–11; bs, 5–12. Differs from baergi microgroup in having relatively fewer setae ( boreus with 15–16, baergi with 16–19 [ P. marksi with 14 in Haradon 1984a: 217, 220], primarily with fewer retrosuperiors ( boreus with 1–2, baergi with 2–3) and prosuperior terminals ( boreus with 1–2, baergi with 2–3).

Paruroctonus boreus (Girard)

Adult specimens of Paruroctonus boreus possess several minor setae among the basitarsal series, especially the superior series, and a minor telotarsal retrosuperior seta adjacent and superior to the retrosuperior terminal seta. The minor setae occur in similar positions throughout samples from Arizona, Colorado, Oregon, Utah, and Washington. A male from St. Anthony Sand Dunes , Fremont County, Idaho, exhibits setae at the loci represented by minor setae but comparable in size to the major setae (these were not included in the counts as major setae due to their apparently homologous positions with the minors) .

Haradon (1985) synonymized Paruroctonus auratus (Gertsch & Soleglad) under P. boreus . The two forms were previously distinguished primarily by differences in pigmentation and morphometrics with P. boreus typically represented as having moderate to strong fuscosity. The type locality for P. boreus , however, is the “Valley of the Great Salt Lake of Utah ” ( Haradon 1985: 25). Interestingly, that population lacks fuscosity ( Haradon 1985: 27), which led Haradon to investigate the taxa and concluded the two were synonymous. Two immaculate specimens (male and female) from “ Oregon,”—determined Paruroctonus auratus by Stahnke—have setal patterns that compare favorably with fuscous P. boreus . Another sample of immaculate specimens from the Great Salt Lake Desert (0.5 mile south of Knolls, Tooele Co., Utah; Figs. 25–29) also contains an FSCA label determining the specimens as P. auratus . Each of these specimens possesses minor setae on the telotarsal superoterminal lobe similar to those of the baergi microgroup, but different from all other P. boreus observed. The significance of this variation is presently unclear and deserves further investigation. Unfortunately, specimens from the Mojave Desert—where the type locality of P. auratus is located—were not obtained for study.

In a large sample of Paruroctonus boreus from rocky, volcanic habitat at Soap Lake, Grant County, Washington, the minor setae on the basitarsus were present yet considerably smaller than those in other samples examined, and about one-fourth to one-third the size of the major setae. Juveniles generally exhibited the basic complement reported here, without minor setae, and with 3 retroventral setae. Basitarsal spinule counts and arrangements deviated little from the illustrated specimen, except that several specimens lacked retroven-