Astaenosiagum Martínez, 1957

Katovich, Kerry, 2008, A generic-level phylogenetic review of the Macrodactylini (Coleoptera: Scarabaeidae: Melolonthinae), Insecta Mundi 2008 (23), pp. 1-78 : 22-23

Astaenosiagum Martínez, 1957

( Figure 27-32 )

Astaenosiagum Martínez, 1957: 50 . Type species Schizochelus longipes F. Philippi, 1861 , by original designation.

Taxonomic Notes

The following generic diagnosis is based on a dissected homeotype of S. longipes , the generic type species. The type species and homeotypes designated by Martínez were borrowed from the MNNC .

Generic diagnosis

This genus is characterized by its elongate body, small size, body flattened in lateral profile, quadrate prementum, with ventral surface medially grooved; oblong pronotum, with lateral margins serrate; elytra with vestiture of long, whitish setae; large, subtriangular pygidium.

Generic redescription

Measurements: Prothorax at widest point of pronotum 3.8 mm, elytra at widest point 6.0 mm, length 10.5 mm.

Color and vestiture: Head and pronotum reddish brown, with vestiture consisting of long whitish setae covering body.

Head: Clypeus coplanar with frons; frons angled at 30 o; labrum in frontal view narrow, ovate, weakly emarginate, labrum coplanar with clypeus; labium with prementum quadrate, ventral surface with a broad, shallow, medial groove ( Fig. 29 ); mandibles in dorsal view subtriangular, scissorial area weakly developed, slightly concave, weakly sclerotized, molar region weakly developed; maxillary palpi with api- cal palpus elongate, ovate, thin in profile, apex with a sensory spot; antennae with 9 antennomeres, antennomeres 7-9 forming the club, club equal to length of antennomeres 2-6 combined.

Prothorax: Pronotum oblong, transverse, widest medially, anterior angle obtuse, lateral margin convex, serrate, posterior angle obtuse, posterior margin straight, medially lobed ( Fig. 30 ); prothoracic leg with coxae transverse; tibia dentate, long spur in distal 1/4; pretarsus with claws slightly divergent, equal in length, both claws widely split, upper lobe narrow, lower lobe broad on individual claw, base of claw toothed.

Mesothorax: Scutellum subtriangular; elytra longer than wide, widest medially ( Fig. 31 ), epipleuron narrow, flattened, dorsal surface with weak striae, interstrial regions slightly raised, surface with short white setae, anterior umbone moderately prominent, posterior umbone absent; pretarsus similar to prothoracic pretarsus.

Metathorax: Coxa narrowly separated; femur narrow, widest medially; tibia vase shape, widest in medially, narrowed in proximal 1/4, posteroventral margin lined with long setae, lacking spurs, posterior margin with a shallow, U-shaped groove; pretarsus with claws similar to prothoracic claws.

Abdomen: Ventrites 1-3 equal in length, sutures distinct, 4 th ventrite (= propygidium) with anterior region equal to length of ventrites 2-3 combined, posterior region of ventrite angled dorsally, membranous, ventrite and sternite of 4 th abdominal segment not separated by distinct suture, spiracle placed in posterior 1/4, situated in slight groove, weak sutural line visible, 5 th ventrite length equal to length of 2 nd ventrite, posterior margin membranous; pygidium large, subtriangular, width subequal to length ( Fig. 32 ).

Diversity and Geographic distribution The monotypic Astaenosiagum is recorded exclusively from Chile.

Figures

Figure 27-32. Astaenosiagum longipes (F. Philippi). 27) Dorsal habitus. 28) Left lateral view. 29) Prementum, ligula and labial palpi, ventral view. 30) Pronotum, dorsal view. 31) Scutellum, and elytra, dorsal view. 32) Pygidium dorsal view.