Ischnotelson peruassu, Lauren A. Esposito & Humberto Y. Yamaguti & Cláudio A. Souza & Ricardo Pinto-Da-Rocha & Lorenzo Prendini, 2017

Lauren A. Esposito, Humberto Y. Yamaguti, Cláudio A. Souza, Ricardo Pinto-Da-Rocha & Lorenzo Prendini, 2017, Systematic Revision of the Neotropical Club-Tailed Scorpions, Physoctonus, Rhopalurus, and Troglorhopalurus, Revalidation of Heteroctenus, and Descriptions of Two New Genera and Three New Species (Buthidae: Rhopalurusinae), Bulletin of the American Museum of Natural History 415, pp. 1-134 : 68-70

Ischnotelson peruassu , sp. nov.

Figures 9 B , 15B , 17B , 19B , 36C, D , 37B, D , 38B , 40

Rhopalurus sp. n. 1: Ubinski et al., 2016: 122.

TYPE MATERIAL: BRAZIL: Minas Gerais: Município Januária: Januária, Parque Nacional Cavernas do Peruaçu : Holotype ♂ ( MZSP 31138 / AMCC [LP 9937]), 15°07′26″S, 44°14′28″W, 4–25.i.2009, R.S. Recoder and M. Teixeira, Jr. Paratypes : 1 ♀ ( UFMG 4820 ), 1 subad. ♀ ( UFMG 4818 ), 1 juv. ♂, 1 juv. ♀ ( UFMG 4824 ), 15°09′0 9″S 44°14′30″W, 17–22.x.2010, G.F.B.P. Ferreira .

DIAGNOSIS: Ischnotelson peruassu , sp. nov., differs from its sister species, I. guanambiensis , as follows. Ischnotelson peruassu is larger, varying from 48–59 mm in total length, than I. guanambiensis , which varies from 35–45 mm. Metasomal segments IV, V, and telson are paler in I. peruassu than in I. guanambiensis . The pedipalp chela fingers are similar in color to the chela manus in I. peruassu but noticeably darker than the manus in I. guanambiensis . The pedipalps and legs are sparsely setose in I. peruassu , but covered by fine setae in I. guanambiensis . The carinae of the carapace are less pronounced in I. peruassu than in I. guanambiensis and the carapace more finely granular in I. peruassu than in I. guanambiensis . The dorsal intercarinal surfaces of the metasoma are smooth in I. peruassu and shagreened in I. guanambiensis . Sternite III is not elevated anteriorly in I. peruassu unlike in I. guanambiensis . Finally, the sexual dimorphism of the adult male I. peruassu is less pronounced than that of the adult male I. guanambiensis : the fixed and movable fingers of the pedipalp chela are shallowly curved proximally and the posterior broadening of the metasoma is less pronounced in the former.

ETYMOLOGY: The specific epithet is a noun in apposition, referring to the type locality, a Brazilian state park covered by savanna that protects important caves.

DESCRIPTION: The following description is based on the holotype male unless otherwise noted (for measurements, see table 3 ). Only characters that differ from the generic description are noted.

Total length: Medium-sized scorpions (total length, 48–59 mm).

Color: Carapace and tergites I–VI brown, tergite VII and metasomal segments I–III dark yellow, metasomal segments IV, V, and telson darker than preceding segments, reddish brown (fig. 40); telson vesicle paler than metasomal segments IV and V, aculeus black; carinae of carapace, tergites, and metasoma dark brown. Sternites yellow. Chelicerae pale yellow; pedipalps yellow, chela fingers similar in color to chela manus; legs yellow, slightly paler than pedipalps.

Carapace: Shape trapezoidal (fig. 15B). Width of anterior margin approximately two thirds that of posterior margin. Anteromedian, median ocular, and posteromedian sulci shallow but well developed, forming single, almost continuous, longitudinal sulcus. Lateral ocular carinae present but weakly developed, central lateral and posterior central submedian carinae distinct, finely granular to costate-granular and fused, forming single nearly continuous, oblique carina, extending along almost entire length of carapace; anterior central submedian carinae distinct, finely granular and separate. Carapace anterior margin with large spinoid granules.

Pedipalps: Pedipalp fingers each with seven oblique subrows (fused basal subrows) of primary denticles and short subrow of terminal denticles ( fig. 17 B). Chela manus slightly incrassate, with fixed and movable fingers shallowly curved proximally, in male. Carinae granular to costate-granular except femur and patella prolateral carinae comprising spiniform granules; chela manus proventral and promedian carinae absent.

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

Sternum: Subtriangular. Median longitudinal sulcus deep throughout, extending from anterior margin to posterior margin.

Genital operculum: Genital opercula suboval, completely divided longitudinally; genital papillae present (♂).

Pectines: Tooth count, 26/26 (♂), 27/27 (♀). Pectinal plate rectangular, width approximately 2× length, median anterior notch present.

Mesosoma: Tergites similar to posterior width of carapace, I–III similar in width, IV and V slightly wider than I–III. Dorsomedian carina absent on I, restricted to posterior half on II–IV, posterior third on VI and V; dorsosubmedian carinae absent on segments I and II, restricted to posterior quarter on III–VI. Tergite VII pentacarinate, dorsomedian carinae present on anterior third but weakly granular. Sternite III not distinctly elevated anteriorly (fig. 19B). Spiracles on sternite III ovoid, width approximately 2× length. Suface of sternites III–VI smooth, sternite VII granular, with four granular carinae.

Metasoma: Metasomal segments longer than wide, but increasing in width posteriorly such that segment V is one third wider than segment I (fig. 37B, D). Carinae well developed, segments I and II with 10 carinae, lateral inframedian carinae of segment III weakly developed; segment IV with 8 carinae; segment V with 5 carinae.

Hemispermatophore: Flagelliform.

Sexual dimorphism: Adult males and females differ as follows. Males are smaller than females in total length. The carinae of the carapace, metasoma, and pedipalps are more finely granular in males than females. The pedipalp chela manus of males is incrassate and the fixed fingers slightly curved proximally (fig. 36D). The chela manus of females is not incrassate (fig. 36D). The metasomal segments are proportionally broader in males, exaggerating the posterior increase in metasomal width, compared to females, in which the metasomal segments are more similar in width. Metasomal segments IV and V, though darker than the preceding segments in both sexes, are relatively paler in females than males.

DISTRIBUTION: This species is known from only two adjacent localities within the Parque Nacional Cavernas do Peruaçu, in the Municipio Januária of northern Minas Gerais state, Brazil (fig. 9B).

ECOLOGY: The known localities are situated on the ecotone of Brazilian caatinga and cerrado, a semiarid environment along the Peruaçu River, close to São Francisco River, which exhibits several microclimates due to topographical variation and the presence or absence of waterbodies. The type specimens were collected on calcareous sandy soil with sparse vegetation, at arid, highelevation localities within the park. The habitat and habitus are consistent with the lapidicolous ecomorphotype ( Prendini, 2001b).

Figures

FIG. 9. Map of northeastern South America, plotting known locality records of six species of Rhopalurusinae Bücherl, 1971: A. Ischnotelson guanambiensis (Lenarducci et al., 2005), comb. nov. (star), Ischnotelson peruassu, sp. nov. (triangle), Physoctonus striatus, sp. nov. (circle), Troglorhopalurus lacrau (Lourenço and Pinto-da- Rocha, 1997), comb. nov (diamonds). B. Physoctonus debilis (C. L. Koch, 1840) (squares), Troglorhopalurus translucidus Lourenço et al., 2004 (crosses).

FIG. 9. Map of northeastern South America, plotting known locality records of six species of Rhopalurusinae Bücherl, 1971: A. Ischnotelson guanambiensis (Lenarducci et al., 2005), comb. nov. (star), Ischnotelson peruassu, sp. nov. (triangle), Physoctonus striatus, sp. nov. (circle), Troglorhopalurus lacrau (Lourenço and Pinto-da- Rocha, 1997), comb. nov (diamonds). B. Physoctonus debilis (C.L. Koch, 1840) (squares), Troglorhopalurus translucidus Lourenço et al., 2004 (crosses).

FIG. 15. Rhopalurusinae Bücherl, 1971, carapace, dorsal aspect. A. Ischnotelson guanambiensis (Lenarducci et al., 2005), comb. nov., ♂ (MZSP). B. Ischnotelson peruassu, sp. nov., paratype ♂ (MZSP). C. Jaguajir agamemnon (C.L. Koch, 1839), comb. nov., ♂ (MZSP). D. Jaguajir pintoi (Mello-Leitão, 1932), comb. nov., ♀ (MZSP). E. Troglorhopalurus translucidus Lourenço et al., 2004, ♀ (MZSP). F. Jaguajir rochae (Borelli, 1910), comb. nov., ♂ (AMNH). Scale bars = 2 mm.

FIG. 17. Rhopalurusinae Bücherl, 1971, pedipalp chela movable finger, dorsal aspect, illustrating dentition (denticle rows). A. Heteroctenus junceus (Herbst, 1800), comb. nov., ♀ (AMNH). B. Ischnotelson peruassu, sp. nov., paratype ♀ (MZSP). C. Jaguajir rochae (Borelli, 1910), comb. nov., ♂ (MZSP). D. Physoctonus striatus, sp. nov., paratype ♂ (MZSP). E. Rhopalurus ochoai, sp. nov., paratype ♀ (AMNH). F. Troglorhopalurus lacrau (Lourenço and Pinto-da-Rocha, 1997), comb. nov., ♀ (MZSP). Scale bars = 2 mm.

FIG. 19. Rhopalurusinae Bücherl, 1971, sternum, pectines and sternite III, ventral aspect. A. Ischnotelson guanambiensis (Lenarducci et al., 2005), comb. nov., ♀ (MZSP). B. Ischnotelson peruassu, sp. nov., paratype ♂ (MZSP). C. Jaguajir agamemnon (C.L. Koch, 1839), comb. nov., ♂ (MZSP). D. Jaguajir pintoi (Mello-Leitão, 1932), comb. nov., ♂ (MZSP). E. Troglorhopalurus translucidus Lourenço et al., 2004, ♀ (MZSP). F. Jaguajir rochae (Borelli, 1910), comb. nov., ♂ (MZSP). Scale bars = 2 mm.

FIG. 36. Ischnotelson, gen. nov., pedipalp chela, retrolateral aspect. A. I. guanambiensis (Lenarducci et al., 2005), comb. nov., ♂ (MZSP). B. I. guanambiensis (Lenarducci et al., 2005), comb. nov., ♀ (MZSP). C. Ischnotelson peruassu, sp. nov., holotype ♂ (MZSP). D. Ischnotelson peruassu, sp. nov., paratype ♀ (MZSP). Scale bars = 2 mm.

FIG. 37. Ischnotelson, gen. nov., metasoma and telson, dorsal (A, B) and ventral (C, D) aspects. A, C. I. guanambiensis (Lenarducci et al., 2005), comb. nov., ♂ (MZSP). B, D. I. peruassu, sp. nov., holotype ♂ (MZSP). Scale bars = 5 mm.

FIG. 38. Ischnotelson, gen. nov., metasoma and telson, lateral aspect. A. I. guanambiensis (Lenarducci et al., 2005), comb. nov., ♂ (MZSP). B. I. peruassu, sp. nov., holotype ♂ (MZSP). Scale bars = 5 mm.

FIG. 40. Ischnotelson peruassu, sp. nov., holotype ♂ (MZSP), habitus, dorsal (A) and ventral (B) aspects. Scale bar = 10 mm.

Tables

TABLE 3 Meristic data for type material of Ischnotelson peruassu, sp. n., Physoctonus striatus, sp. n., and Physoctonus debilis (C. L. Koch, 1840). Measurements follow Prendini (2000, 2003, 2004). 1 Sum of carapace, tergites I – VII, metasomal segments I – V, and telson; 2 sum of metasomal segments I – V and telson; 3 measured from base of condyle to tip of fixed finger.

		I. peruassu		P. debilis		P. striatus
		Holotype ♂	Paratype ♀	♂	♂	Holotype ♂	Paratype ♂
		MZSP	UFMG	MZSP	MZSP	MZSP	MZSP
Total length1		31138 58.7	4818 48.6	30866 26.5	31158 28.1	31128 25.9	30869 22.5
Prosoma	length	7.0	6.2	3.1	3.4	3.1	2.9
	ant. width	4.2	3.8	2.2	2.3	1.3	1.3
	post. width	7.2	6.2	3.7	4.0	3.3	3.0
Mesosoma Metasoma	total length total length2	16.5 35.2	12.0 30.4	7.8 15.6	7.7 17.0	7.4 15.4	6.2 13.4
Segment I	length	4.7	4.0	2.1	2.2	2.3	1.5
	width	4.1	3.5	1.9	2.0	1.7	1.3
	height	3.4	2.9	1.6	1.6	1.3	1.3
Segment II	length	5.3	4.5	2.3	2.5	2.6	2.3
	width	4.2	3.6	1.8	1.9	1.6	1.6
	height	3.4	3.0	1.5	1.6	1.3	1.3
Segment III	length	5.7	4.8	2.5	2.7	2.4	2.3
	width	4.7	3.6	1.9	2.0	1.8	1.7
	height	3.6	3.0	1.5	1.5	1.4	1.3
Segment IV	length	6.1	5.3	2.7	3.1	2.7	2.6
	width	5.2	4.0	2.1	2.2	2.1	2.0
	height	3.6	3.0	1.5	1.6	1.4	1.3
Segment V	length	7.2	6.3	3.2	3.4	3.0	2.8
	width	4.9	3.8	2.0	2.2	2.2	1.9
	height	3.2	2.7	1.5	1.6	1.3	1.3
Telson	total length	6.2	5.5	2.8	3.1	2.4	1.9
Vesicle	length	3.6	3.3	1.8	1.9	1.4	1.2
	width	1.7	1.7	1.1	1.2	1.1	0.9
	height	2.1	2.0	1.1	1.1	1.0	0.9
Aculeus	length	3.4	2.9	1.4	1.6	1.3	1.0
Pedipalp	total length	26.9	23.4	12.5	13.8	11.9	10.9
Femur	length	6.9	6.0	3.0	3.2	2.9	2.4
	width	2.0	1.8	0.9	1.0	0,8	0.8
	height	1.4	1.3	0.7	0.8	0.7	0.7
Patella	length	7.7	6.6	3.4	3.8	3.3	2.9
	width	2.5	2.3	1.3	1.5	1.1	1.2
	height	2.1	1.7	0.9	1.0	1.0	0.7
Chela	length3	12.3	10.8	6.1	6.8	5.7	5.6
Manus	width	3.2	2.1	1.4	1.5	1.3	1.4
	height	3.2	2.2	1.3	1.2	1.1	1.2
Mov. finger	length	8.2	7.3	4.3	4.8	4.0	4.0
Pectines	total length	5.2	4.9	2.2	2.5	2.5	2.0
	basal width	1.8	1.4	0.9	1.0	0.9	0.9
	tooth count	26/26	27/27	14/13	14/15	15/15	17/17