Rhopalurus Thorell, 1876

Figures 1 F, 2E, 5, 6, 11C, E, 12C, 16C–F, 17E,

20C–F, 21H–J, 22H–J, 24I–R, 52–60

Rhopalurus laticauda Thorell, 1876, type species by original designation.

Rhopalurus Thorell, 1876 a: 9; 1876 b: 143–145; Karsch, 1879 a: 18; 1879 b: 118, 119, 122; Mello-Campos, 1924 a: 252, 253, 267, 283– 285, pl. 7, fig. 31; Werner, 1927: 357; Lutz, 1928: 72, 73, figs. 1–3; Mello-Leitão, 1932: 15; Meise, 1934: 32; Prado, 1940: 27, 35; Prado and Rios-Patiño, 1940: 41; Hum- melinck, 1940: 139; Mello-Leitão, 1940: 51; Roewer, 1943: 219; Mello-Leitão, 1945: 266, 280–284, figs. 115–117; Caporiacco, 1947: 20; 1951: 4; Scorza, 1954 a: 190, 201, figs. 15, 16; 1954b: 160; 1954c: 166; Bücherl, 1959: 268; 1967: 112; 1969: 767; Esquivel de Verde and Machado-Allison, 1969: 33; Bücherl, 1971: 327; Lucas and Bücherl, 1972: 263; Francke, 1977 a: 133, fig. 12; Stahnke and Calos, 1977: 119; Vachon, 1977: 300, figs. 24, 28; González-Sponga, 1978: 201, figs. 9, 277, 278; Lourenço, 1979: 215, figs. 1, 3, 4; 1981: 545, fig. 2; 1982a: 108, 115, 117, 134–136, 138, figs. 12, 13, 25–46, 78; Cekalovic, 1983: 190; González-Sponga, 1984: 72–74; Lourenço, 1984 b: 14; 1986 a: 132–134, figs. 3–9, 13, 14; 1986b: 170, fig. 7; 1988: 169, figs. 13, 15; Lourenço and Flórez, 1990: 71; Lou- renço, 1991a: 282, fig. 5; 1991b: 117; Flórez, 1991: 119; Lourenço, 1992: 55; 1994: 157; González-Sponga, 1996: 118, 137, figs. 314– 319; Lourenço, 1997 b: 67, figs. 9, 10, 12, 14, 15; Lourenço and Pinto-da-Rocha, 1997: 184, 185, fig. 21; Kovařík, 1998: 118; Lourenço et al., 2000: 141; Manzanilla and Sousa, 2003: 3–12; Fet and Lowe, 2000: 219– 221; Lourenço, 2002: 96, 98, 99, 111, figs. 205–224; Fet et al., 2003 b: 23, 24; Lenar- ducci et al., 2005: 2, 7; Prendini and Wheeler, 2005: 481, table 10; Teruel, 2006: 50–52; Rojas-Runjaic and Sousa, 2007: 6; Lourenço, 2007: 359; Kamenz and Prendini, 2008: 9, table 2, pl. 40–44; Lourenço, 2008: 1, 2, 3, 5, 7, 12, figs. 1, 4–9; Teruel and Roncallo, 2008: 1, 2, 5, 8, 10, figs. 1–7; Teruel and Tietz, 2008: 1, 6, 8, 10, 11, figs. 5–9; Volschenk et al., 2008: 651, 652, 654, 658– 661, 663, 664, 674, figs. 1B, D, 2E, tables 1, 2; Prendini et al., 2009: 222, 223; Outeda- Jorge et al., 2009: 44–46; Brazil and Porto, 2010: 57, 79; Teruel and Roncallo, 2013: 112, 113; Teruel and Cozijn, 2013: 1; Loria and Prendini, 2014: 25, table 5; Lourenço, 2014: 69, 74, 75; Ubinski et al., 2016: 122.

Centrurus (part): Kraepelin, 1891: 123, 137–139; Kraepelin, 1899: 89, 95; 1908: 187, 190, 194; Penther, 1913: 240; Waterman, 1950: 168.

DIAGNOSIS: Rhopalurus differs from Centruroides, Heteroctenus, Jaguajir, gen. nov., and Troglorhopalurus by the fused central lateral and posterior central submedian carinae of the carapace; from Centruroides, Ischnotelson, gen. nov., Physoctonus and Troglorhopalurus by the presence of a pecten-sternite stridulatory organ (proximal pectinal teeth, dorsal surfaces without nodules but with regular striations, sternite III, ventromedian carina elevated anteriorly, ventrosubmedian surfaces forming paired depressions, finely and irregularly granular, lateral margins forming smooth, raised carina); from Centruroides and Troglorhopalurus by the robust metasoma, increasing in width posteriorly (more so in the adult male); from Heteroctenus by the absence of depressions in the male pectinal plate and the presence of a subaculear tubercle on the telson; from Ischnotelson by the separate (unfused) lateral ocular and central lateral carinae of the carapace and the telson vesicle not laterally compressed; from Jaguajir by the separate (unfused) lateral ocular and anterior central submedian carinae of the carapace; from Physoctonus by the larger size (30–70 mm), the more distinct carapacial carinae (at least the posterior central submedian carinae), the setose proximal dorsal fulcra of the pectines, the incrassate pedipalp chela manus of the adult male, the bifurcate prolateral pedal spur of leg I, and the oblique subrows of primary denticles on the pedipalp chela fingers flanked closely by pro- and retrolateral accessory (supernumerary) denticles; and from Troglorhopalurus by the proximal dentate margin of the chela fixed and movable fingers of the adult male emarginate, with a distinct gap evident between them, when closed.

DESCRIPTION: The following general description outlines characters common to the species of Rhopalurus.

Total length: Medium-sized, compact scorpions (total length, 30–70 mm).

Color: Carapace and tergites I–VI dark brown, tergite VII light brown (fig. 1F). Coxosternal region, pectines and sternites pale yellow. Metasomal segments I–III, dorsal surfaces yellowish to orange, IV and V, dorsal surfaces brown, darker than preceding segments; I–III, ventral surfaces darker than dorsal surfaces, IV and V, ventral surfaces darker than I–III, V almost black, darker than IV; I–IV each with dark ventromedian and/or ventrosubmedian stripes or solid band of pigmentation. Telson vesicle brown, paler than metasomal segment V, aculeus almost black. Chelicerae and legs brown, similar to carapace. Pedipalps yellowish to orange, chela fingers dark brown.

Chelicerae: Base, dorsal surface with medial transverse row of well-developed tubercles.

Carapace: Median ocular tubercle raised (fig. 16C–F); two median ocelli; three pairs of lateral macroocelli; one pair of lateral microocelli. Anteromedian, median ocular, and posteromedian sulci well developed, forming single, almost continuous, longitudinal sulcus. Lateral ocular and anterior central submedian carinae indistinct, finely granular and separate (unfused); central lateral and posterior central submedian carinae distinct, finely granular, and fused into single slightly oblique carina, extending almost two thirds the length of carapace.

Pedipalps: Pedipalp femur retrolateral accessory carinae absent. Pedipalp chela manus of adult male incrassate, fixed and movable fingers curved proximally (fixed finger curved dorsally, movable finger curved ventrally), such that proximal dentate margin emarginate, distinct gap present between fingers proximally, when closed (fig. 52), manus of female not incrassate, fixed and movable fingers not curved proximally, such that proximal dentate margin sublinear, little or no gap present between them proximally, when closed (fig. 53); manus, proventral and promedian carinae absent; fixed and movable fingers, median denticle rows respectively comprising eight and nine oblique subrows of primary denticles flanked closely by pro- and retrolateral accessory (supernumerary) denticles; movable finger without proximal lobe (fig. 17 E). Pedipalps orthobothriotaxic Type A, α configuration; femur with five dorsal trichobothria, trichobothrium d 2 situated on prolateral surface; patella trichobothrium d 3 situated retrolateral to dorsomedian carina; chela fixed finger trichobothrium db proximal to trichobothrium et.

Legs: Legs III and IV, tibial spurs absent; I–IV, basitarsi each with bifurcate prolateral pedal spur; telotarsi each with irregular tufts of fine, acuminate macrosetae.

Pectines: Pectinal plate without depressions (male), anterior margin with sulcus (fig. 20C– F). Pectines proximally expanded, at least 1.5× wider proximally than medially; proximal dorsal fulcra setose; pectinal teeth straight, proximal teeth, dorsal surfaces without nodules but with regular striations (figs. 11C, E, 12C), dorsobasal surfaces without macrosetae; pectinal sensillae peg shaped.

Mesosoma: Tergites IV–VI wider than I–III (figs. 57–60); I–VI tricarinate, dorsosubmedian carinae vestigial or absent; dorsomedian carinae vestigial, reduced to posterior third of I–VI. Tergite VII pentacarinate, dorsomedian carina complete. Sternites smooth, carinae absent or obsolete; sternite III, lateral margins forming smooth, raised carina, ventromedian carina elevated anteriorly, ventrosubmedian surfaces forming paired depressions, finely and irregularly granular anterolaterally; respiratory spiracles (stigmata) width more than 5× length.

Metasoma: Metasoma robust, increasing in width posteriorly, segment V ca. 2× width of segment I in adult male, only slightly wider than I in adult female (figs. 54–56). Segments I–III each with 10 distinct, costate-granular carinae, IV with eight distinct, costate-granular carinae, V with seven distinct, costategranular carinae; dorsosubmedian carinae obsolete, reduced to rows of granules on dorsal surfaces of segments I–IV, more pronounced on segment I; dorsolateral carinae complete on segments I–IV, and terminating in prominent, spiniform granules posteriorly on II–IV, absent on V; lateral supramedian carinae complete on segments I–V; lateral inframedian carinae complete on segments I–III, absent on IV and V; ventrosubmedian carinae complete on segments I–IV, restricted to anterior third of V; ventromedian carina absent on segments I–IV, complete on V. Intercarinal surfaces densely and coarsely granular, especially on dorsal surfaces of segments I–III and ventral surfaces of I–V.

Telson: Vesicle subspherical, not laterally compressed, narrower than metasoma V; anterodorsal lateral lobes prominent; lateral and ventral surfaces granular, acarinate, or with obsolete ventromedian carina; subaculear tubercle vestigial to subspinoid.

Hemispermatophore: Flagelliform; flagellum, elongate and narrow (fig. 24I–R); trunk markedly concave; three lobules, ental (LI), ectal (LE), and basal (LB); LI inclined slightly to sinistral side relative to axis of trunk and continuous until flagellar base; flagellar base narrow, one third maximum width of trunk; LE length approximately two thirds that of LI, with sharp tip and varying from very curved (in R. caribensis) to straight (in R. laticauda), width half that of LB; LB short, carina shaped with rhomboid tip, angle between LB and LE 75° (R. caribensis) to 80° (R. laticauda).

Cytogenetics: The diploid chromosome number of R. laticauda (table 2) is 2n = 22 (Ubinski et al., 2016).

INCLUDED SPECIES: Rhopalurus caribensis Teruel and Roncallo, 2008; Rhopalurus laticauda Thorell, 1876; Rhopalurus ochoai, sp. nov.

DISTRIBUTION: The genus Rhopalurus is endemic to the Guiana Shield of northern South America and recorded from Brazil, Colombia, Guyana, Venezuela, and several islands and island archipelagos in the southern Caribbean (Venezuelan territory): Isla Coche; Isla Cubagua; Isla Margarita; Isla La Peche, Archipiélago de Los Frailes; Isla La Tortuga; Isla Pico [Morro Pando], Archipiélago de Los Hermanos; Archipiélago de Los Roques; Angoletta and Isla Conejo, Archipiélago de Los Testigos (figs. 5, 6).

ECOLOGY: The species of Rhopalurus inhabit open savanna-grassland vegetation, including caatinga and cerrado formations, and large tree clearnings in the tropical rain forests of Amazonia (fig. 2E, F). The habitat and habitus are consistent with the lapidicolous ecomorphotype (Prendini, 2001 b).

REMARKS: The consistent paraphyly of Rhopalurus in the analyses by Esposito et al. (in review) and the identification of several welldefined, monophyletic groups, comprising species formerly assigned to Rhopalurus, justifies its redefinition and restriction to three species from northern South America (fig. 13). This finding is also consistent with the cytogenetic study of Ubinski et al. (2016), which identified a diploid chromosome number of 2n = 22 for R. laticauda (table 2).