Schizochelus Blanchard, 1850

Katovich, Kerry, 2008, A generic-level phylogenetic review of the Macrodactylini (Coleoptera: Scarabaeidae: Melolonthinae), Insecta Mundi 2008 (23), pp. 1-78 : 62-64

Schizochelus Blanchard, 1850

( Figure 161-166 )

Schizochelus Blanchard, 1850: 89 . Type species Schizochelus flavescens Blanchard, 1850 , by subsequent designation ( Evans 2003: 346).

Taxonomic Notes

The following generic diagnosis is based on a dissected homeotype of the presumptive syntype of the type species S. flavescens located at the MNHC, identified with a Blanchard label .

Generic diagnosis

This genus is similar in appearance to Macrodactylus , but can be characterized by its oblong, transverse pronotum, widest in anterior 1/4.

Generic redescription

Measurements: Prothorax at widest point of prothorax 2.5 mm, elytra at widest point of elytra 3.2 mm.

Color and vestiture: Body brown, elytral surface with a vestiture consisting of dense yellow setae, remaining surface of body with scattered yellowish setae.

Head: Clypeus not coplanar with frons; frons angled at 30 o; labrum in frontal view, narrowly ovate, weakly emarginate, labrum coplanar with clypeus; labium with prementum rectangular, elongate (2X longer than wide), ventral surface with medial groove ( Fig. 163 ); mandibles in dorsal view rectangular, scissorial area reduced to a membrane, lined with dense setae, molar area bluntly produced, weakly sclerotized; maxillary palpi with apical palpus ovate, equal to length of segments 2-3 combined, apex acute, with blunt sensory region; antennae with 10 antennomeres, antennomeres 7-9 forming the elongate club, lamellae thin, equal to length of antennomeres 2-7 combined.

Prothorax: Pronotum oblong, transverse, wider than long, widest in anterior 1/4, anterior angle acute, lateral margin convex, posterior angle acute, posterior margin concave, medially lobed ( Fig. 164 ); prothoracic leg with coxa elongate; tibia lacking tooth, ventral margin medially with a spur ( Fig. 165 ); pretarsus with claws divergent, equal in length, both claws narrowly split, upper lobe narrow, slightly longer than lower lobe, lower lobe narrow on individual claw, base of claw toothed.

Mesothorax: Scutellum narrowly subtriangular; elytra longer than wide, widest medially, in lateral profile epipleuron flattened, membranous, dorsal surface with six weakly raised striae, anterior and posterior umbones strongly developed; pretarsus similar to prothoracic pretarsus.

Metathorax: Metathoracic leg with coxa widely separated; femur narrowly ovate, narrow proximally, widest medially; tibia subtriangular, narrow proximally, widest medially, posteroventral margin lacking spurs, posterior margin with a deep, U-shaped groove; pretarsus with claws similar to those of prothoracic and mesothoracic legs.

Abdomen: Ventrites 2-4 subequal in length, medially grooved ( Fig. 166 ), 5 th visible ventrite (= propygidium) equal to length of ventrites 3-4 combined, posterior margin membrane-like, ventrite and sternite of 5 th abdominal segment lacking suture, spiracle placed posteromedially, 6 th ventrite equal to length of 5 th ventrite, triangular in lateral profile; pygidium subtriangular, width equal to length, posterior margin rounded.

Diversity and Geographic Distribution Schizochelus comprises seven species, all known only from Brazil or Chile. No key to species exists.

Figures

Figure 161-166. Schizochelus flavescens Blanchard (male). 161) Dorsal habitus. 162) Left lateral view. 163) Prementum, ligula and labial palpi, ventral view. 164) Head and pronotum, dorsal view. 165) Prothoracic tibia. 166) Visible abdominal segments.