Key to the genera and species of Odontocroton and Rhinobatesia

[Users of the key should bear in mind that the author did not have specimens of O. flavirostris, O. monnei and O. sanguinolentus to study, nor females of O. melzeri, O. soror and O. apicalis .]

1. Antennomere XI not dentate or weakly dentate; not robust, length body/width metasternum in male 5.42–8.30, in female 5.24–6.05; pronotum tuberculate or apex of elytra yellow or ochreous; lengths of elytra/forebody 1.36–1.50; width/length of rostrum 2.07–2.50; width of one inferior lobe of eyes/interocular distance in male 4.50–11.15, in female 0.83–1.40; length of elytra/ width across humeri 3.45–4.13; lengths metatarsomere I/II+III 1.40–1.55 (Fig. 1–34); South America....................................... [ Odontocroton Clarke n. gen.] 2

— Antennomere XI strongly dentate; robust, length body/width metasternum in male 5.16, in female 4.58; pronotum not tuberculate and apex of elytra dusky; lengths of elytra/ forebody; 1.13–1.21; width/length of rostrum 1.61–1.68; width of one inferior lobe of eyes/ interocular distance in male 3.40, in female 2.00; length of elytra/width across humeri 2.67–2.76; lengths metatarsomere I/II+III 0.74–0.94 (Fig. 35–39); Mexico, Central America.................................. Rhinobatesia rugicollis (Bates, 1880)

2(1). Smaller, 9.3–12.7 mm, slender species, length body/width metasternum in male 6.45–8.30, in female 6.05; basal constriction of prothorax not fossate; antennae filiform, basal segments fimbriate below; metafemoral clave fusiform, shorter than peduncle; base of mesosternal process 3–6× narrower than coxal cavity; genitalia: lateral lobes of tegmen narrow, parallel and not narrowed to apex (Fig. 1–13).................................. [Group A] 3

— Larger, 13.1–17.1 mm (but see O. monnei), less slender species, length body/width metasternum in male 5.42–5.85, in female 5.24–5.36; basal constriction of prothorax fossate; antennae subfiliform to subcrassate, basal segments with dense, thick setae (but see O. septemtuberculatus); metafemoral clave cylindrical, distinctly longer than peduncle; base of mesosternal process approximately 2× narrower than coxal cavity; genitalia: lateral lobes of tegmen broad, divergent and narrowed to apex (Fig. 14–34)................................... [Group B] 6

3(2). Antennae shorter, reaching apical third of urosternite II; elytra narrowly fissate........... 4 — Antennae longer, reaching apex of urosternite III; elytra dehiscent or fissate.............. 5

4(3). Antennae shorter, reaching apical third of urosternite II; pronotum uneven but not tuberculate; apex of elytra ochreous, reaching apex of urosternite III; male abdomen cylindrical and hardly annulate, soleate depression on urosternite V with strongly raised sides, abdominal process with approximately 45° slope (Fig. 9–10); Brazil (SC)......... O. melzeri (Fisher, 1952)

— Antennae longer, reaching base of urosternite III; pronotum tuberculate; apex of elytra yellow, reaching basal quarter of urosternite IV; male abdomen subcylindrical and distinctly annulate, soleate depression on urosternite V with weakly raised sides, abdominal process vertical (Fig. 11–13); Brazil (GO, MG, ES, SP).......................... O. soror (Gounelle, 1911)

5(3). Antennae shorter, reaching apical third of urosternite II; prothorax comparatively short, length/ width 1.09; elytra dehiscent or fissate, apex reaching middle of urosternite IV; abdominal process not coplanar with abdomen, with approximately 30° slope (Fig. 1–6); Brazil (GO, BA, MG, ES, RJ, SP, PR, SC, RS), Bolivia (SC, TA), Paraguay, Argentina (MI, BA), Uruguay ........................................... O. flavicauda (Bates, 1873)

— Antennae longer, reaching apex of urosternite III; prothorax elongate, length/width 1.45; elytra not dehiscent nor fissate, apex reaching apex of urosternite IV; abdominal process almost coplanar with abdomen, with approximately 10° slope (Fig. 7–8); Brazil (BA, ES).............................................. O. flavirostris (Melzer, 1930)

6(2). Length body/width metasternum in male 5.42–5.85, in female 5.24; pronotum without distinct callosities, with or without median callus, the pronotal surface almost lacking impunctate areas; antennae subcrassate; apex of elytra reach urosternite V; width of one inferior lobe of eyes/interocular distance in male 8.00–9.00; abdominal process with approximately 60–80° of slope in male, approximately 45° in female; lengths mesofemoral clave/peduncle 1.72–1.78; length mesofemur/lateral width of clave 3.24–3.56; lengths metafemur/metatibia 1.04–1.08...................................................... [Group B (i)] 7

— Length body/width metasternum in male 5.42–5.54, in female 5.36–5.43; pronotum with distinct paired lateral callosities or tubercles and median callus, the surface of these partly impunctate; antennae subfiliform; apex of elytra reach urosternite IV; width of one inferior lobe of eyes/interocular distance in male 4.50–6.40; abdominal process with approximately 45° of slope in male, approximately 30° in female; lengths mesofemoral clave/peduncle 1.52-1.67; length mesofemur/lateral width of clave 3.78–3.95; lengths metafemur/metatibia 1.00–1.02.................................................... [Group B (ii)] 10

7(6). Female: larger, 14 mm; antennomere III 1.3× longer than scape and IV approximately 1/2 length of III....................................................................... 8

— Female: smaller, 11 mm; antennomere III 1.5× longer than scape and IV 2/3 length of III (Fig. 14); Uruguay .......................................... O. monnei (Zajciw, 1968)

8(7). Both sexes: legs bicolored (reddish and black); sides of prothorax more rounded. Female: pronotum orange, humeri yellow or black, pronotal midline occupied by black fascia; elytra weakly fissate, 3.4x longer than width across humeri, apical yellow fascia elongate, ill-defined and not contrasting in color with rest of elytra; metafemora red and black. In male: antennae reach middle of urosternite I, antennomere III 1.4× longer than scape and equal in length to V and VI; prosternal process 10x narrower than width of coxal cavity; abdomen orange in color, lengths of urosternites III and IV subequal, soleate depression on urosternite V ill-defined, weakly delimited by slightly raised, rounded sides; abdominal process with approximately 60° slope....................................................................... 9

— Both sexes: legs unicolored (black in male, yellowish in female); sides of prothorax less rounded. Female: pronotum and humeri entirely dark red; elytra dehiscent, 3.6× longer than width across humeri, apical yellow fascia short, quadrate and contrasting in color with rest of elytra; metafemora unicolored. In male: antennae reach base of urosternite II, antennomere III 1.2× longer than scape and distinctly longer than all other segments; prosternal process 8.5× narrower than width of coxal cavity; abdomen dark brown in color, urosternite III distinctly longer than IV, soleate depression on urosternite V U-shaped, but hardly depressed, sharply raised sides towards apex of segment; abdominal process with approximately 80° slope (Fig. 15–18); Brazil (MG, ES, RJ, RS), Argentina, Uruguay ......... O. apicalis (Klug, 1825)

9(8). Female: head black; antennae short, approximately 1/2 length of body, antennomeres III–V short and strongly widened; sides of prothorax regularly rounded; pronotum without calli, surface densely and coarsely punctured, midline occupied by broad black fascia; sides of elytra (including humeri) broadly blackish, translucent panels densely punctured, apices of elytra with both lateral and sutural margins dentate; femora entirely blackish (Fig. 19); Brazil (BA, MG, ES, RJ, SP, PR, SC, RS), Argentina (MI, CO, ER), Uruguay .................................................................... O. sanguinolentus (Bates, 1873)

— Female: head mostly rufous; antennae longer, more than 1/2 length of body; antennomeres III–V longer and hardly widened; sides of prothorax irregularly rounded; pronotum with indistinct calli, surface densely but not coarsely punctured, midline with narrow black fascia; sides of elytra narrowly blackish, humeri entirely yellowish, translucent panels sparsely punctured, apices of elytra with only sutural margin weakly dentate; femora red and black (Fig. 20–24); Brazil (SC)........................................... O. rufifrons (Fisher, 1937)

10(6). Black; elytra yellow at apex; metasternum with dense white pubecence; rostrum shorter, width/ length 2.40 in male, 1.93 in female; width of one inferior lobe of eye/interocular distance 6.40 in male, 1.40 in female; antennae shorter, reaching basal third of urosternite II in male, apical third of I in female; in male antennomere III 1.05x longer than any other segment, in female 1.15× longer; pronotal surface only partly impunctate on callosities, these weaker and not tuberculate; elytra shorter in male, length/width across humeri 3.56; soleate depression on urosternite V with strongly raised sides, almost tuberculate (Fig. 25, 27-30); Argentina (CO, TU), Bolivia (SC, TA)........................... O. quinquecallosus (Zajciw, 1963)

— Rufescent; elytra not yellow at apex; metasternum with dense golden pubecence; rostrum longer, width/length 2.08 in male, 2.07 in female; width of one inferior lobe of eye/interocular distance 4.50 in male, 1.25 in female; pronotal surface with many impunctate areas (not only on callosities), largest callosities tuberculate; elytra longer in male, length/width across humeri 3.84; soleate depression on urosternite V with weakly raised sides (Fig. 26, 31–34); Argentina (SA, TU), Bolivia (SC, TA) O. septemtuberculatus (Zajciw, 1963)