Dynastini, MacLeay, 1819

Rowland, J. Mark & Miller, Kelly B., 2012, Phylogeny and systematics of the giant rhinoceros beetles (Scarabaeidae: Dynastini), Insecta Mundi 2012 (263), pp. 1-15 : 11-13

Key to subtribes and genera of Dynastini

The key is based on the morphology of males that fully express the secondary sexual traits.

1.

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Apex of cephalic horn acuminate ( Augosoma , Dynastes , Golofa , Haploscapanes , Eupatorus , Beckius , Pachyoryctes , Chalcosoma ) or bifurcate ( Allomyrina , Xylotrupes , Trypoxylus , Xyloscaptes , Megasoma ); if acuminate then pronotum has a medial horn ( Augosoma , Dynastes , Golofa ) or is essentially hornless (female-like Golofa ); if essentially hornless then anterolateral pronotal integument is immaculate to punctate ( Golofa ), never cristate and distinctly anastomosing (as in Haploscapanes ), and mandibular incisors are bidentate (with rare exceptions); lateral contours of paramere apex converging inward ( Dynastina ) or parallel to diverging outward ( Xylotrupina ) ............ 2 ( Dynastina MacLeay and Xylotrupina Hope )

Apex of cephalic horn acuminate ( Haploscapanes , Eupatorus , Beckius , Pachyoryctes , Chalcosoma ); pronotum without a medial horn ( Haploscapanes , Eupatorus , Beckius , Pachyoryctes , Chalcosoma ). or with paired more or less medial horns ( C. mollenkampi , E. birmanicus ), or with more or less lateral horns ( C. atlas , C. caucasus , Beckius , all other Eupatorus ), or with

2(1).

— horn-like transverse lateral carinae ( Pachyoryctes ); if pronotum is essentially female-like, without obvious male ornaments, then anterolateral pronotal integument is anastomosing and cristate ( Haploscapanes barbarossa , H. inermis ); lateral contours of paramere apex converging inward (except Beckius ) and apex setation absent or nearly so; mandibular incisors adenticulate ................................................................................................. 9 ( Chalcosomina , new subtribe)

Cephalic horn apex acuminate ( Augosoma , Dynastes , Golofa ) or bifurcate ( Megasoma ); if bifurcate then mandibular incisor denticles diverge strongly, usually at least 45 o; mesal pronotal horn or boss present ( Augosoma , Dynastes , most Megasoma , most Golofa ) or absent (female-like Megasoma and Golofa ); if horn or boss absent then mandibular incisor denticles diverge strongly as above ( Megasoma ) and paramere blades are on a similar plane as or below that of paramere orifice ( Megasoma , Golofa ); pronotal medial horn or medial boss usually with dense ventral pilosity; lateral contours of paramere apex converging inward; Africa, America ....................... ................................................................................................................. 3 ( Dynastina MacLeay )

Cephalic horn bifurcate; mandibular incisor adenticulate ( Trypoxylus , Xyloscaptes , Allomyrina , Xylotrupes florensis ) or denticulate and denticles diverge at most 30 o (other Xylotrupes ); pronotal horn lacking dense pilosity ( Xylotrupes , Trypoxylus , Xyloscaptes ) except when entire dorsal surface of body is densely hirsute ( Allomyrina ); lateral contours of paramere apex parallel or diverging outward; Asia ............................................................................ 6 ( Xylotrupina Hope )

3(2).

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Pronotum with ventrolateral undercut carinae; mesal pronotal horn without ventral dense pilosity; anterolateral pronotal integument with anastomosing, cristate sculpture; Africa .................... ................................................................................................................... Augosoma Burmeister

Pronotum without such ventrolateral carinae; mesal pronotal horn usually with ventral dense pilosity; anterolateral pronotal integument without anastomosing, cristate sculpture ......... 4

4(3).

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Cephalic horn apex bifurcated to form two lateral tines; mandibular incisor denticles usually diverge at least 45 o; anterior margin of clypeus broadly emarginate, forming two widely separated denticles; America .............................................................................................. Megasoma Kirby

Cephalic horn apex acuminate; mandibular incisor denticles diverge at most 30 o; anterior margin of clypeus narrowly emarginate or not emarginate 5

5(4).

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Relative size of mandibular incisor denticles subequal; when a pronotal horn present then angle between posterior pronotal margin and apex of pronotal horn at least 30 o (may be up to 80 o); in species with pronotal horn, cephalic horn has weakly to strongly serrated lateral margins; cephalic horn rarely with multiple medial denticles ( G. eacus , G. spatha ); pronotal horn without laterally paired accessory horns; America ............................................................... Golofa Hope

Relative size of mandibular incisor denticles varies from strongly positive to strongly negative; angle between posterior pronotal margin and apex of pronotal horn at most 10 o; cephalic horn without serrated dorsolateral margins; with one or more dorsomedial denticles (often weak or obscure in D. tityus ); pronotal horn with laterally paired accessory horns (except D. satanas ); America c ............................................................................................................... Dynastes Kirby

6(2).

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Plane of paramere blades strongly angled toward paramere orifice, or parameres with strong frontal notch ( X. florensis ); with two strongly sclerotized raspulae of similar structure, or if only one raspula then basal metatarsomere dorsally strongly acuminate ( X. florensis ); pronotal horn with basolateral carinae [obscure in small taxa] or, rarely, basolateral denticles ( X. florensis ); pronotal horn apex extends beyond cephalic horn apex in large species; Asia ......... .............................................................................................................................. Xylotrupes Hope

Plane of paramere blades essentially same as or below that of paramere orifice; with at least one sclerotized raspular spine, if two spines then they are grossly dissimilar in structure; pronotal horn without basolateral carinae or denticles; pronotal horn apex never extends to cephalic horn apex .......................................................................................................................................... 7

7(6).

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8(7).

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Small species, at most 40mm in total length; dorsal integument heavily hirsute; protarsal claws distinctly asymmetrical; Asia ........................................................................ Allomyrina Arrow

Large species, at least 50mm and up to 85mm in total length; dorsal integument nearly immaculate or finely hirsute; protarsal claws symmetrical or essentially so ............................................... 8

Cephalic horn very long (~ 25mm), apex divided into four lateral tines; pronotal horn short, narrow; Asia .................................................................................................... Trypoxylus Minck

Cephalic horn of moderate length (~ 15mm), apex bifurcated into two lateral tines and with two lateral denticles at midlength; pronotal horn stout, short; Asia ............... Xyloscaptes Prell

9(1).

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