Parabuthus setiventer, Prendini & Esposito, 2010

Prendini, Lorenzo & Esposito, Lauren A., 2010, A reanalysis of Parabuthus (Scorpiones: Buthidae) phylogeny with descriptions of two new Parabuthus species endemic to the Central Namib gravel plains, Namibia, Zoological Journal of the Linnean Society 159 (3), pp. 673-710 : 698-705

PARABUTHUS SETIVENTER SP. NOV.

( FIGS 1–4 , 5C, D , 6D , 7D–F , 13 , 14B–E , 15–17 )

Holotype: Namibia: Erongo Region: Swakopmund District: Namib-Naukluft Park: Gobabeb , pitfall site on gravel plains c. 1 km north, 23°32′39.6″S, 15°02′57.4″E, 27.iii.2006, L. Prendini, T. L. Bird & S.K. Uunona, 422 m, UV detection on cool, still, dark night, becoming windy and colder later, on Central Namib gravel plains with low granite outcrops north of Kuiseb River , very sparse Stipagrostis grass tussocks in places, 1 ♂ (SMN 2918).

Paratypes: Namibia: Erongo Region: Swakopmund District: Arandis Control Site, Rössing Mine Survey , 22°22′S, 14°59′E , 8.v–5.vi.1984, E. Griffin , preservative pitfall traps, 1 ♀ (SMN 841) , 5.vi–3.vii.1984, J. Irish & H. Rust , preservative pitfall traps, 1 ♂ (SMN 854) , 8.xii.1984 – 14.i.1985, J. Irish & H. Rust , preservative pitfall traps, 1 ♀ (SMN 879) , 28.xii.1984 – 14.i.1985, J. Irish & H. Rust , preservative pitfall traps, 1 ♀ (SMN 875) , 14.i–11.ii.1985, J. Irish & H. Rust , preservative pitfall traps, 1 ♂ (SMN 883) , 11.ii– 11.iii.1985, J. Irish & H. Rust , preservative pitfall traps, 2 ♂ (SMN 889) , 11.iii–9.iv.1985, J. Irish & H. Rust , preservative pitfall traps, 1 ♀ (SMN 903) , 5.iv– 6.v.1985, E. Griffin, preservative pitfall traps, 1 ♂, 2 ♀ (SMN 924); Panner Gorge, Rössing Mine Survey, 22°29′S, 15°01′E, 13.iii–9.iv.1984, E. Griffin , preservative pitfall traps, 1 ♂ (SMN 853) , 9.iv–8.v.1984, E. Griffin , preservative pitfall traps, 1 ♀ (SMN 836) , 8.v–5.vi.1984, E. Griffin , preservative pitfall traps, 1 ♀ (SMN 843) , 18.xii–14.i.1984, J. Irish & H. Rust , preservative pitfall traps, 1 ♂, 1 juvenile ♂ (SMN 880) , 14.i–11.ii.1985, J. Irish & H. Rust, preservative pitfall traps, 1 ♂ (SMN 885); Lower Ostrich Gorge , Rössing Mine Survey, 22°30′S, 14°58′E , 8.v–5.vi.1984, E. Griffin , preservative pitfall traps, 1 ♂ (SMN 844) , 27.ix–22.x.1984, J. Irish & H. Rust , preservative pitfall traps, 1 ♀ (SMN 868) , 3.iii–9.iv.1984, E. Griffin , preservative pitfall traps, 1 ♂ (SMN 823) , 9.iv–8.v.1984, E. Griffin, preservative pitfall traps, 2 ♀ (SMN 837); Upper Ostrich Gorge , Rössing Mine Survey, 22°30′S, 14°58′E , 13.iii–9.iv.1984, E. Griffin , preservative pitfall traps, 1 ♀, 1 juvenile ♂ (SMN 828) , 9.iv–8.v.1984, E. Griffin , preservative pitfall traps, 1 juvenile ♀ (SMN 834) , 20.xi–18.xii.1984, E. Griffin , preservative pitfall traps, 1 ♂, 1 subadult ♂ (SMN 876) , 11.ii–11.iii.1985, E. Griffin , preservative pitfall traps, 1 ♂ (SMN 892) , 5.iv–6.v.1985, E. Griffin, preservative pitfall traps, 2 ♂ (SMN 914); Deblin Mine (a few km south), east-north-east of Swakopmund, 22°31′S, 14°45′E, 20.ii.1982, A. Harington, 1 ♂ [ AMNH ( AH 3632 )], 1 ♀ [ AMNH ( AH 3633 )]; Namib- Naukluft Park: Gobabeb, gravel plains around camp and immediately on northern bank of Kuiseb River , 23°33′36.2″S, 15°02′23.45″E , 19.i.2009, L. Prendini , T . L. Bird & J. Huff, 405 m, Central Namib gravel plains, UV detection on cool, moonless night, slight breeze, syntopic with P. glabrimanus sp. nov., 1 ♂ ( AMNH); Gobabeb, pitfall site on gravel plains c. 300 m north-east, 23°33′30″S, 15°02′50″E , 26.iii.2006, L. Prendini , T . L. Bird & S.K. Uunona, 300 m, 1 ♀ ( AMNH), L. Prendini, C. Bird & T . Iipinge , 415 m, UV detection on warm, dark, windy night on Central Namib gravel plains with low granite outcrops north of Kuiseb River , very sparse Stipagrostis grass tussocks in places, 1 ♂ ( AMNH); Gobabeb, pitfall site on gravel plains c. 600 m north, 23°33′05.8″S, 15°02′47.9″E , 26.iii.2006, L. Prendini, C. Bird & T . Iipinge , 420 m, UV detection on warm, dark, windy night on Central Namib gravel plains with low granite outcrops north of Kuiseb River , very sparse Stipagrostis grass tussocks in places, 1 ♂ ( AMNH), 23°33′06″S, 15°02′50″E , 27.iii.2006, L. Prendini , T . L. Bird & S.K. Uunona , 395 m, UV detection on cool, still, dark night, becoming windy and colder later, on Central Namib gravel plains with low granite outcrops north of Kuiseb River , very sparse Stipagrostis grass tussocks in places, specimens collected moving about on surface, 1 ♂ ( AMNH); Gobabeb, pitfall site on gravel plains c. 700 m north, 23°32′54.4″S, 15°02′49.5″E , 27.iii.2006, L. Prendini , T . L. Bird & S.K. Uunona , 395 m, UV detection on cool, still, dark night, becoming windy and colder later, on Central Namib gravel plains with low granite outcrops north of Kuiseb River , very sparse Stipagrostis grass tussocks in places, specimens taken in open sandy ground, 3 ♂ ( AMNH), 2 subadult ♂ (SMN 2919); Gobabeb, pitfall site on gravel plains c. 1 km north, 23°32′39.6″S, 15°02′57.4″E , 26.iii.2006, L. Prendini, C. Bird & T . Iipinge , 422 m, UV detection on warm, dark, windy night on Central Namib gravel plains with low granite outcrops north of Kuiseb River , very sparse Stipagrostis grass tussocks in places, 1 ♀ ( AMNH) , 27.iii.2006, L. Prendini , T . L. Bird & S.K. Uunona , 422 m, UV detection on cool, still, dark night, becoming windy and colder later, on Central Namib gravel plains with low granite outcrops north of Kuiseb River , very sparse Stipagrostis grass tussocks in places, 1 ♂, 2 ♀ ( AMNH); Gobabeb, 3.1 km north, 23°32′55.5″S, 15°02′48.6″E , 19.i.2009, L. Prendini , T . L. Bird & J. Huff, 426 m, Central Namib gravel plains with low granite outcrops, little other vegetation, UV detection on cool, moonless night, slight breeze, specimen walking on gravel plains, 1 ♀ ( AMNH); Welwitschiavlakte, c. 1 km north of turnoff to Giant Welwitschia , 22°39′30″S, 15°01′35.9″E , 30.iii.2006, L. Prendini , T . L. Bird & S.K. Uunona , 437 m, UV detection on cool, still, dark night on Central Namib gravel plains leading up to rocky schist slope, specimen collected on gravel plain, 1 ♂ ( AMNH); Welwitschiavlakte, mountain and gravel plain south of campsite, 22°39′15.6″S, 15°00′18.3″E , 30.iii.2006, L. Prendini , T . L. Bird & S.K. Uunona , 440 m, UV detection on cool, still, dark night on Central Namib gravel plains with sparse annual grasses leading up to schist mountain slope, specimens collected on gravel plain, 4 ♂ (AMNH).

Diagnosis: Parabuthus setiventer sp. nov. is most closely related to P. nanus , the two species forming a monophyletic sister group to P. gracilis ( Fig. 2 ). Parabuthus setiventer sp. nov. may be separated from P. nanus and all other species of Parabuthus by means of the following combination of characters: small adult size, carapace length 2.5–5.0 mm; carapace, including median ocular tubercle (male, female), entirely granular; pedipalp chela movable finger of female moderate, compared with manus (measured along ventroexternal carina), length finger/length manus: ±1.50; pedipalp chela manus of adult male, slightly incrassate, compared with that of adult female, which is slender; pedipalp chela manus granular; pedipalp chela with trichobothrium dt situated proximal to et; pedipalp femur and patella trichobothria d 2 absent or very reduced; sternites III–VI, punctate, moderately setose ( Fig. 6D ), VII, metasomal segments I and, to a lesser extent, II–IV, ventral surfaces densely covered in short, truncate macrosetae, becoming progressively less numerous, and acuminate from segments I–IV; metasomal segments slender (length IV/width IV: 1.7–2.11); metasomal segment I, ventrosubmedian carinae absent; metasomal segments II and III, posteroventral margins demarcated by transverse row of isolated, round granules; metasomal segment IV, acarinate; metasomal segments IV and V, lateral intercarinal surfaces granular; metasomal segment V, dorsosubmedian, dorsolateral, and ventromedian carinae absent, ventrolateral carinae present, converging distally, and with posterior spiniform granules enlarged into spinose processes.

Etymology: The species name refers to the densely setose sternite VII that is characteristic of the species ( Fig. 6D ).

Description: The following description is based on the holotype male, two paratype males, and three paratype females ( Table 6).

Colour: Carapace, tergites, and metasomal segments I–IV, segment V, anterior third: Buff-Yellow no. 53. Metasomal segment V, posterior two-thirds and telson infuscated: Dark Brownish Olive no. 129. Chelicerae, pedipalps, legs, pectines, and sternites slightly paler than carapace, tergites, and metasoma ( Fig. 13 ). Chelicerae, pedipalps, legs, and sternites: Sulfur Yellow no. 157. Pectines: Pale Horn Color no. 92.

Carapace: As for P. glabrimanus sp. nov., except as follows. Carapace covered entirely by uniform, coarse granulation, becoming coarser on interocular and posterolateral surfaces. Anterior and posterior margins of carapace sublinear ( Fig. 5C, D ).

Chelicerae: As for P. glabrimanus sp. nov.

Sternum: As for P. glabrimanus sp. nov. ( Fig. 13B, D ).

Pedipalps: As for P. glabrimanus sp. nov., except as follows. Pedipalps covered in short macrosetae ( Figs 13B–E , 14 ). Femur surfaces uniformly, finely granular (♂), external and ventral intercarinal surfaces with smooth areas (♀) ( Fig. 15C ); dorsointernal, dorsoexternal, and ventrointernal carinae distinct, granular; internomedian carina comprising discontinuous row of spiniform granules; externomedian carina obsolete, granular; other carinae absent. Patella intercarinal surfaces uniformly, finely granular (♂), external intercarinal surfaces with smooth areas (♀) ( Fig. 15A, B ); dorsointernal carina obsolete, reduced to few granules proximally and distally; ventrointernal carina vestigial, reduced to single spiniform granule, proximally; internomedian carina comprising prominent spiniform granule, proximally, and few smaller granules, distally; other carinae absent. Chela finely granular ( Fig. 14B–E ); acarinate. Chela long, slender (♀) or slightly incrassate (♂), length along ventroexternal carina 29–51% greater than chela width and 42–54% greater than chela height ( Table 6); length of movable finger 13–29% (♂) or 40–47% (♀) greater than length along ventroexternal carina. Chela fixed and movable fingers straight, such that proximal dentate margin linear when fingers closed ( Fig. 14B–E ). Median denticle row of chela fixed and movable fingers each comprising eight or nine oblique primary subrows; each subrow comprising three to six small denticles and large external denticle, flanked by internal and external accessory denticles; terminal subrow of fixed finger usually shorter than others; basal subrow of fixed and movable fingers longer, comprising fusion of basal and sub-basal subrows; each finger with enlarged terminal denticle.

Trichobothria: Neobothriotaxic minor, Type A, a configuration ( Figs 14B–E , 15 ), with following segment totals: femur, ten (four dorsal, four internal, two external), patella, 12 (four dorsal, one internal,

Holo., holotype; Para., paratype.

*Sum of carapace, tergites I–VII, metasomal segments I–V, and telson.

†Sum of metasomal segments I–V and telson.

‡Measured from base of condyle to tip of fixed finger.

§Sinistral pecten damaged.

seven external) and chela, 15 (eight manus, seven fixed finger). Total number of trichobothria per pedipalp, 37. Femur d 2 absent or very reduced; e 1 situated level with or distal to d 5. Patella d 2 absent or very reduced; esb 2 situated level with esb 1. Chela Esb situated in line with or dorsal to Eb 2 – Et axis; eb situated proximal to basal dentate margin of fixed finger; dt situated proximal to et.

Mesosoma : Pre-tergites smooth, matt (♂), smooth, shiny (♀), granular along posterior margins. Posttergites entirely covered with uniform, fine granulation, becoming coarser posteriorly, especially along posterior margins; I–VII each with weakly developed, costate-granular dorsomedian carina; VII additionally with distinct pairs of costate-granular dorsosubmedian and dorsolateral carinae, and well-developed stridulatory surface between dorsosubmedian carinae, comprising rounded granules reaching posterior margin. Sternites III–VI surfaces smooth, punctate, moderately setose, lateral and posterior margins each with few macrosetae; VII acarinate, punctate, uniformly finely granular (♂) or smooth medially with sparse fine granules laterally (♀), densely covered in short, truncate macrosetae ( Fig. 6D ). Sternite VII, width 24–38% (♂) or 33–40% (♀) greater than length.

Pectines: As for P. glabrimanus sp. nov., except as follows ( Fig. 13B, D ). Pectinal teeth: 25–32/26–32 (♂), 22–30/23–31 (♀) ( Table 6).

Genital operculum: Completely divided longitudinally. Genital papillae present (♂), absent (♀).

Legs: As for P. glabrimanus sp. nov. ( Fig. 16 ).

Metasoma and telson: Metasomal segments I–V width/length ratio progressively decreasing ( Table 6), width percentage of length 69–85% (♂) or 76–85% (♀) for I, 60–66% (♂) or 65–75% (♀) for II, 57–63% (♂) or 61–69% (♀) for III, 52–56% (♂) or 54–62% (♀) for IV, and 48–51% (♂) or 50–56% (♀) for V. Telson oval, globose, height 51–61% (♂) or 54–62% (♀) of length, with flattened dorsal surface, rounded ventral surface; vesicle not distinctly narrower than metasomal segment V, width 66–74% (♂) or 70–79% (♀) of metasomal segment V. Aculeus short, sharply curved, 65–85% (♂) or 71–89% (♀) of vesicle length ( Table 6). Metasoma and telson 54–57% (♂) or 52–55% (♀) of total length. Intercarinal surfaces entirely granular, except for posterodorsal surfaces, which are smooth and matt (♂) or shiny (♀); segments I–III, each with well-developed dorsal stridulatory surface, comprising fine rounded granules extending to posterior margin ( Fig. 7E, F ); segments II and III, posterodorsal edge sublinear. Metasomal segments I–V, dorsal and lateral surfaces and V, ventral surface, moderately to densely covered with long, acuminate macrosetae, especially on ventral surface of telson; I and, to a lesser extent, II–IV, ventral surfaces densely covered in short, truncate macrosetae, becoming progressively less numerous, and acuminate from segments I–IV ( Fig. 7D ). Metasomal segments I–III each with eight carinae; IV acarinate; V with two carinae. Dorsosubmedian carinae present, converging posteriorly on segments I–III, absent on IV and V. Dorsolateral carinae present on segments I–III, absent on IV and V. Median lateral carinae present on segment I only. Ventrolateral carinae present, converging posteriorly on segments I–III; posterior section not forming U-shaped pattern on II and III; reduced to anterior row of isolated, rounded granules on IV; subparallel to converging posteriorly on V, with posterior spiniform granules enlarged into spinose processes ( Fig. 7D ). Ventrosubmedian carinae absent on segment I, present on II and III; reduced to anterior row of isolated, rounded granules on IV; absent on V. All metasomal carinae costate-granular to granular.

Hemispermatophore: Flagelliform, with pars recta S-shaped ( Fig. 17 ).

Geographical variation: There is little variation amongst specimens from different localities.

Ontogenetic variation: As in other species of Parabuthus , male resembles female very closely until the final instar ( Prendini, 2004a). Juveniles and subadults may be readily sexed by examination of the pectines and genital aperture.

Sexual dimorphism: Unlike most species of Parabuthus , P. setiventer sp. nov. is not markedly dimorphic in the shape of the pedipalp chela manus or the structure of the pectines. The manus of adult male is only slightly incrassate, compared with that of adult female ( Fig. 14B–E , Table 6). As in most species of Parabuthus , the first proximal median lamella of each pecten is suboval, mesially enlarged, and lobate in the female, but unmodified in the male ( Prendini, 2004a). However, the pectinal tooth counts of the male (25–32) and female (22–31) are similar ( Table 6). The adult male is proportionally more slender, with a longer metasoma and more pronounced granulation and carination, than the adult female ( Figs 5C, D , 13 , Table 6).

Distribution: Endemic to the gravel plains of the Central Namib, north of the Kuiseb River, in the Erongo Region (Swakopmund District) of western Namibia ( Fig. 1 ). The known records fall within the range of 300–450 m elevation. Parabuthus glabrimanus sp. nov. is more commonly found at higher elevation (400–1100 m), further east. Parabuthus setiventer sp. nov. is protected in the Namib-Naukluft Park.

Ecology: Parabuthus setiventer sp. nov. is a semipsammophilous species, which displays several ecomorphological adaptations to its sandy habitat: basitarsi of legs I, II, and, to a lesser extent, III dorsoventrally compressed, with comb-like rows of long macrosetae (‘sand combs’) on the retrolateral margins ( Fig. 16A–C ); metasoma lacking carinae on segments III–V ( Fig. 7D ). Specimens of P. setiventer sp. nov. have been taken in pitfall traps and collected with UV light detection on cool or warm, dark, still, or windy nights, moving about on the surface of gritty gravel plains between low granite outcrops.

Parabuthus setiventer sp. nov. has been collected in sympatry with the following scorpion species: Bothriuridae : L. elegans ; Buthidae : P. glabrimanus sp. nov.; Scorpionidae : O. penrithorum . Its distribution is allopatric with that of its sister species, P. nanus ( Fig. 1 ).

Figures

Figure 1. Map showing the known distributions of Parabuthus glabrimanus sp. nov. (triangles), Parabuthus gracilis Lamoral, 1979 (squares), Parabuthus nanus Lamoral, 1979 (stars) and Parabuthus setiventer sp. nov. (circles) in Namibia and South Africa. Contour interval, 500 m. Major sand systems stippled. Magnified inset shows distributions of P. glabrimanus and P. setiventer in finer detail.

Figure 2. See Table 2 for details. The optimal tree retrieved by analyses with equal weights and implied weights under k = 3–6 (Table 2). This topology corresponds to the majority rule (> 50%) consensus of most parsimonious trees (MPTs) obtained by seven analyses in which weighting regime was varied; frequency percentages for nodes that collapsed in the strict consensus of the MPTs obtained by the seven analyses are indicated to the right of relevant nodes. Zero-length branches are collapsed. Solid bars indicate uniquely derived apomorphic character states, whereas empty bars indicate parallel derivations of apomorphic states under accelerated transformation (ACCTRAN) optimization. The number above each bar gives the character number, whereas the number below gives the character state. Branch support values are circled at nodes. Refer to Appendix for character descriptions. The East African species are indicated with asterisks. Alternative topologies for nodes A and B shown in Figures 3 and 4 respectively.

Figure 3. Alternative topologies for node A (Fig. 2) retrieved by analysis with equal weights. See Table 2 for details.

Figure 4. Alternative topologies for node B (Fig. 2) retrieved by analyses with equal weights and implied weights under k = 3–6 (A) and with implied weights under k = 1 and 2 (B, C). See Table 2 for details.

Figure 5. Parabuthus glabrimanus sp. nov. (A, B) and Parabuthus setiventer sp. nov. (C, D), carapace, dorsal aspect. A, holotype ♂ (SMN 2901). B, paratype ♀ (AMNH). C, holotype ♂ (SMN 2918). D, paratype ♀ (AMNH). Scale bars = 2 mm.

Figure 6. Parabuthus glabrimanus sp. nov. (A), Parabuthus gracilis Lamoral, 1979 (B), Parabuthus nanus Lamoral, 1979 (C) and Parabuthus setiventer sp. nov. (D), sternites III–VII, ventral aspect. A, ♂ [AMNH (AH 2164)]. B–D, ♂ (AMNH). Scale bars = 2 mm.

Figure 7. Parabuthus glabrimanus sp. nov. (A–C) and Parabuthus setiventer sp. nov. (D–F), metasoma and telson. A, D, ventral aspect. B, C, E, F, dorsal aspect. A, B, holotype ♂ (SMN 2901). C, paratype ♀ (AMNH). D, E, holotype ♂ (SMN 2918). F, paratype ♀ (AMNH). Scale bar = 2 mm.

Figure 13. Parabuthus setiventer sp. nov., habitus. A, B, holotype ♂ (SMN 2918). C, D, paratype ♀ (AMNH). A, C, dorsal aspect. B, D, ventral aspect. Scale bar = 10 mm.

Figure 14. Parabuthus nanus Lamoral, 1979 (A) and Parabuthus setiventer sp. nov. (B–E), dextral pedipalp chela, showing trichobothrial distribution. A, ♂ [AMNH (LP 1269)], external aspect. B, holotype ♂ (SMN 2918), external aspect. C–E, paratype ♀ (AMNH), external (C), ventral (D), and internal (E) aspects. Scale bar = 1 mm.

Figure 15. Parabuthus setiventer sp. nov., paratype ♀ (AMNH), dextral pedipalp patella and femur, illustrating trichobothrial distribution. A, patella, dorsal aspect. B, patella, external aspect. C, femur, dorsal aspect. Scale bar = 1 mm.

Figure 16. Parabuthus setiventer sp. nov., paratype ♀ (AMNH), dextral legs I–IV, tibia, basitarsus, and telotarsus, retrolateral aspect, illustrating setae, ungues, and spurs. A, leg I. B, leg II. C, leg III. D, leg IV. Scale bar = 1 mm.

Figure 17. Parabuthus setiventer sp. nov., paratype ♂ (AMNH), dextral hemispermatophore, ental (A) and ectal (B) aspects. Scale bar = 2 mm.