1	Sternum subtriangular; pedipalp tibia without ventral trichobothria	Family Buthidae: 3
–	Sternum subpentagonal	2
2	Retrolateral pedal spurs absent; anterior margin of carapace with a strong concavity; three lateral eyes; three ventral trichobothria on the tibia	Family Hormuridae, Genus Opisthacanthus , O. heurtaultae
–	Retrolateral pedal spurs present; anterior margin of carapace without a strong concavity; two lateral eyes in most species; four to seven ventral trichobothria on the tibia	Family Chactidae: 16
3	Dentate margins of pedipalp chela fingers composed of 6/7 longitudinal rows of granules, without supernumerary granules	4
–	Dentate margins of pedipalp chela fingers composed of 8 to 17 oblique rows of granules	12
4	Presence of fulcra in the pectines	Genus Isometrus , I. maculatus
–	Pectines without fulcra	5
5	Small species; very small pectines (pectinal tooth count 10–10) with distal teeth rounded	Genus Microananteris , M. minor
–	Small to large species; pectines small to long (pectinal count ranging from 11 to 19), distal teeth not rounded	Genus Ananteris : 6
6	Chelicerae with reticular pattern	7
–	Chelicerae without reticular pattern	10
7	General coloration yellow to pale yellow; very small species (9 mm)	A. intermedia
–	Darker general coloration, brownish yellow; larger species (14–33mm)	8
8	Chelicerae reticular pattern incomplete, only a dark brown spot anteriorly at the base of fingers	A. coineaui
–	Reticular pattern complete, over the entire surface of the chelicerae	9
9	Small pectines with only 11 to 12 teeth in males	A. polleti
–	Pectinal tooth count 17–17 in males	A. kalina sp. n.
10	General coloration pale yellow without spots or pigmented zones on the body and its appendages; movable fingers with six linear rows of granules	A. elisabethae
–	General coloration brownish yellow marbled with dark reddish brown spots; movable fingers with seven linear rows of granules	11
11	Movable fingers with one accessory granule present at the base of each row	A. guyanensis
–	Movable fingers with two accessory granules present at the base of each row	A. sabineae
12	Dentate margins of pedipalp chela fingers composed of 8/9 oblique rows of granules, with supernumerary granules present in the adults	Genus Jaguajir , Jaguajir pintoi kourouensis
–	Dentate margins of pedipalp chela fingers composed of 12 to 17 oblique rows of granules, without supernumerary granules	Genus Tityus : 13
13	Small species ranging from 25 to 45 mm in total length with variegated pigmentation and a very rhomboidal subaculear tooth	14
–	Species of medium or large size, ranging from 63 to 100 mm in total length; pigmentation varying from yellowish to brown and black; spinoid subaculear tooth	15
14	Dorsolateral keels of metasomal segments I to IV with a moderate spinoid posterior granule	T. mana
–	Dorsolateral keels of metasomal segments I to IV without a spinoid posterior granule	T. silvestris
15	Species of medium size (63 mm in total length); coloration rather pale varying from yellowish to reddish brown or brownish, never black; basal middle lamellae of female pectines not dilated	T. gasci
–	Large species, ranging from 75 to 100 mm in total length; pigmentation blackish in the adult and yellowish/variegated in immature individuals; basal middle lamellae of female pectines dilated	T. obscurus
16	Spiracles linear; tarsus with two rows of spines	Genus Brotheas : 28
–	Spiracles oval or round; tarsus with setae or rows of spines	17
17	Tarsus with setae	18
–	Tarsus with rows of spines	Genus Guyanochactas : 29
18	Small scorpions, from 13 to 28 mm in total length; spiracles round	19
–	Scorpions of medium size, from 44 to 50 mm in total length; spiracles round to round/oval	Genus Broteochactas , B. delicatus
19	Metasomal segments stocky in relation to the body, especially segments IV-V; fingers about the same length as chela hand	Genus Hadrurochactas : 20
–	Metasomal segments moderately stocky in relation to the body	21
20	General coloration reddish brown, with a confluent yellowish longitudinal median stripe over the tergites; chelicerae yellowish without spots; male pectinal tooth count ranging from 10–11	H. schaumii
–	General coloration yellowish brown, without confluent yellowish longitudinal median stripe; chelicerae with variegated brownish spots over the entire surface; male pectinal tooth count 9–9	H. cristinae sp. n.
21	Pedipalp chela stocky; fingers shorter than chela hand	Genus Auyantepuia : 22
–	Pedipalp chela slender with fingers strongly curved; spinoid granules on dorsal and dorso-lateral carinae of metasomal segments II-IV	Genus Spinochactas , S. mitaraka
22	Pedipalps with chelae weakly granulated, almost smooth	23
–	Pedipalps with chelae moderately to strongly granulated	26
23	Ventral side of several metasomal segments yellowish, without spots	24
–	Ventral side of all metasomal segments well pigmented, brownish to dark reddish	25
24	Posterior half of ventral side of segments I to IV yellowish, without spots; confluent yellowish longitudinal median stripe on tergites	A. aluku sp. n.
–	Ventral side of metasomal segments I to III yellowish, without spots; no median stripe on tergites	A. laurae
25	Body, pedipalps, legs and chelicerae without variegated brownish spots	A. gaillardi
–	Body, pedipalps, legs and chelicerae marked with variegated brownish spots	A. kelleri
26	Ventral side of metasomal segments I to II yellowish, without spots; confluent yellowish longitudinal median stripe on tergites	27
–	Ventral side of all metasomal segments well pigmented, brownish to dark reddish; no median stripe on tergites	A. fravalae
27	General coloration reddish brown; metasomal tegument with medium size granulation on ventral side of segments III to V	A. aurum sp. n.
–	General coloration yellowish; only metasomal segment V granulated ventrally	A. sissomi
28	Carapace and tergites strongly granular; general coloration blackish brown	B. granulatus
–	Carapace feebly granular; tergites punctate; general coloration reddish brown	B. gervaisii
29	General coloration reddish yellow with some blackish spots; chela fingers with six rows of granules	G. gonzalezspongai
–	General coloration pale yellowish, without any dark spots; chela fingers with five rows of granules	G. flavus