Alvarinus Blanchard, 1850

Katovich, Kerry, 2008, A generic-level phylogenetic review of the Macrodactylini (Coleoptera: Scarabaeidae: Melolonthinae), Insecta Mundi 2008 (23), pp. 1-78 : 16-17

Alvarinus Blanchard, 1850

( Figure 7-11 )

Alvarinus Blanchard, 1850: 123 . Type species Alvarinus hilarii Blanchard, 1850 , by subsequent designation ( Evans 2003). Corminus Burmeister, 1855: 39 . Type species Corminus canescens Burmeister, 1855 , by subsequent designation ( Evans 2003). [New Synonym]

Taxonomic Notes

The following generic diagnosis is based on a homeotype of the presumptive syntype of the type species A. hilarii , located at the NMNH and identified with a Blanchard label. A syntype of C. canescens , type species of Corminus Burmeister (MLUH) was also used to verify the generic limits of Alvarinus .

Generic diagnosis

The genus is characterized by its elongate body, semicircular labrum and elongated clypeus in frontal view, quadrate prementum, with ventral surface medially lobed; the antennae with nine antennomeres, with antennomeres 7-9 forming an elongate club, the length of which equals the combined length of antennomeres 2-6.

Generic redescription

Measurements ( Alvarinus hilarii ): Prothorax at widest point 3.5 mm, elytra at widest point 4.4 mm, elytral length 8.6 mm.

Color and vestiture ( Alvarinus hilarii ): Body dark brown to black, vestiture consisting of dense, yellow to gold setae.

Head: Clypeus not coplanar with frons; frons angled at 45 o; labrum in frontal view semicircular, small, slight medial groove ( Fig.9 ), labrum not coplanar with clypeus; labium with prementum quadrate, medially lobed, surface flattened ( Fig. 10 ); mandibles in dorsal view rectangular, scissorial area bluntly produced into a thin rectangular process, molar area prominent; maxillary palpi with apical palpus ovate, equal to length of 2 nd segment, apex obtuse; antennae with 9 antennomeres, antennomeres 7-9 forming the elongate club, equal to the length of antennomeres 2-6 combined ( Fig. 11 ).

Prothorax: Pronotum oblong, transverse, widest medially, anterior angle obtuse, lateral margins convex, posterior angle obtuse, posterior margin convex, medially lobed, dorsal surface rounded; prothoracic leg with coxa transverse; tibia dentate or bidentate, pretarsus with claws divergent, equal in length, both claws narrowly split, upper lobe narrow, lower lobe broad on individual claw.

Mesothorax: Scutellum subtriangular; elytra longer than wide, widest in posterior 2/3, elytral epipleuron forming a narrow bead, dorsal surface with two weak, vertical striae, striae smooth, interstrial region punctate, anterior umbone prominent, posterior umbone weak; pretarsus similar to prothoracic pretarsus.

Metathorax: Coxae clearly separated; femur ovate, widest medially; tibia triangular, narrow proximally, widest medially, posteroventral margin with a pair of large, stout spurs, anterior spur shorter than posterior spur, spurs arising at same level as tarsal articulation joint, posterior margin with a shallow, U-shaped groove; claws similar to prothoracic claws.

Abdomen: Ventrites 2-4 subequal in length, 5 th ventrite (= propygidium) equal to length of ventrites 3- 4 combined, ventrite and sternite of 5 th abdominal segment not separated by a distinct suture, partial groove present, spiracle located medially, 6 th ventrite equal to length of 4 th ventrite length, posterior margin concave medially; pygidium subtriangular, wider than long.

Diversity and Geographic Distribution

Alvarinus currently comprises 16 Brazilian, Argentinean, Bolivian, and Ecuadorian species. No spe-

cies level key is currently available for members of this genus.

Figures

Figure 7-11. Alvarinus canescens (Burmeister) (male). 7) Dorsal habitus. 8) Left lateral view. 9) Clypeus and labrum, frontal view. 10) Prementum, ligula and labial palpi, ventral view. 11) Antenna.