Macrodactylini

Katovich, Kerry, 2008, A generic-level phylogenetic review of the Macrodactylini (Coleoptera: Scarabaeidae: Melolonthinae), Insecta Mundi 2008 (23), pp. 1-78 : 11-12

Key to the Macrodactylini Genera

The key is based on the type species only and is representative primarily of males. Specific characters are illustrated to facilitate identification. All Macrodactylini can be distinguished from other melolonthine tribes by the following: length of the fifth ventrite longer than the fourth ventrite when viewed ventrally (Fig. A), fifth ventrite lacking a complete suture between the tergite and sternite (Fig. B), and the metathoracic tibial spurs (if present) offset, allowing the metatarsus to move past them (Fig. C).

1. Mesosternal process extending anteriorly to prosternum ( Fig. 144 ); 5 th ventrite (=propygidium) raised medially along anterior aspect, posteriorly raised into a prominent process ( Fig. 145 ) .. .............................................................................................................................. Pectinosoma

— Mesosternal process never extending anteriorly to prosternum; 5 th ventrite (=propygidium) variable, never raised into a prominent process. .................................................................................... 2 2(1). Pronotum with posterior margin bearing a single, narrow, acuminate process medially ( Fig. 15 ); 1 st abdominal ventrite with posterior margin bearing a narrow, blunt acuminate process medially, process extending nearly to posterior margin of 3 rd ventrite ( Fig. 16 ) ................ Ancistrosoma

— Pronotum with posterior margin variable, never with a single narrow, acuminate process medially; 1 st abdominal ventrite with posterior margin straight, never with an acuminate process medially .................................................................................................................................................. 3

3(2). Clypeus with dorsolateral angles strongly projecting dorsally, forming “horns” ( Fig. 51 ), in dorsal view anterior angles strongly produced dorsoanteriorly, forming a pair of long “horns” ........... ............................................................................................................................ Ceratolontha

— Clypeus often produced forwardly into a trapezoidal process, but not forming “horns” ............. 4

4(3). Clypeus projecting anteriorly, with lateral margins strongly indented ( Fig. 158 ), surface of prementum with raised carinae, one medial and one U-shaped ( Fig.160 ) .............. Rhinaspis

— Clypeus with lateral margin never strongly indented; prementum variable .............................. 5

5(4). Meso- and metathoracic claws simple .......................................................................................... 6

— Meso- and metathoracic claws split .............................................................................................. 7

6(5). Elytra often clothed in scale-like setae; 5 th ventrite with medial surface bearing a semicircular, recessed pocket, margins of which are raised ..................................................... Calodactylus

— Elytra not clothed in scale-like setae; 6 th ventrite with medial surface bearing a semicircularshaped pocket, margins of which are raised ( Fig. 81 ) .................................................... Dasyus

7(5). Pronotum widest anteriorly, posterior angles acute ( Fig. 103 ); pygidium longer than wide, posterior margin concave ( Fig. 104 ); prementum elongate and flattened ( Fig.102 ); small beetles (5.5-5.8 mm long) ........................................................................................................................ Hercitis

— Pronotum widest medially or posteriorly, posterior angles variable; pygidium variable, if longer than wide, never with the posterior margin concave; prementum variable, if elongate and flattened, always with the pygidium wider than long; beetles usually greater that 5.6 mm long .................................................................................................................................................. 8

8(7). Prementum rectangular, ligula narrowed between labial palpi, strongly produced anteriorly, often appearing bilobed ( Fig. 149 and 150 ); pretarsus of meso- and metathoracic claws often unequal in length ........................................................................................................................ Plectris

Figures

Figure 141-145. Pectinosoma elongatum Arrow (male). 141) Dorsal habitus. 142) Left lateral view.143) Prementum, ligula and labial palpi, ventral view. 144) Mesosternum, ventral view. 145) Visible abdominal segments.

Figure 12-16. Ancistrosoma trinitatis Arrow (male). 12) Dorsal habitus. 13) Left lateral view. 14) Prementum, ligula and labial palpi, ventral view. 15) Pronotum, dorsal view. 16) Visible abdominal segments, ventral view.

Figure 49-53. Ceratolontha venezuelae Arrow. 49) Dorsal habitus. 50) Left lateral view. 51) Clypeus, labrum and pronotum, lateral view. 52) Prementum, ligula and labial palpi, ventral view. 53) Pronotum, dorsal view.

Figure 156-160. Rhinaspis aenea (Billberg) (male). 156) Dorsal habitus.157) Left lateral view. 158) Clypeus and head, dorsal view. 159) Labrum and clypeus, frontal view. 160) Prementum, ligula and labial palpi, ventral view.

Figure 77-81. Dasyus collaris Le Peletier and Serville. 77) Dorsal habitus. 78) Left lateral view. 79) Prementum, ligula and labial palpi, ventral view. 80) Pronotum, dorsal view. 81) Visible abdominal segments, ventral view.

Figure 100-104. Hercitis pygmaea Burmeister. 100) Dorsal habitus. 101) Left lateral view. 102) Prementum, ligula and labial palpi, ventral view. 103) Pronotum, dorsal view. 104) Pygidium, dorsal view.

Figure 146-150. Plectris micans (Bates). 146) Dorsal habitus. 147) Left lateral view. 148) Clypeus and labrum, frontal view. 149) Prementum, ligula and labial palpi, ventral view. 150) Plectris tomentosa Le Peletier and Serville prementum, ligula and labial palpi, ventral view.