Parallidiostoma Ocampo & Colby

Ocampo, Federico C. & Colby, Julia, 2009, Parallidiostoma tricornum Ocampo and Colby, a new genus and species of Allidiostomatinae from Peru (Coleoptera: Scarabaeidae), Zootaxa 2287, pp. 64-68 : 65

Parallidiostoma Ocampo & Colby new genus

( Figs. 1–6 )

Type species: Parallidiostoma tricornum Ocampo & Colby , here designated.

Diagnosis. Parallidiostoma is distinguished from Allidiostoma by the following combination of characters: in Parallidiostoma the prontoum is nearly as long as it is wide (ratio 0.95) (in Allidiostoma the pronotum is strongly transverse, ratio <0.76), Parallidiostoma lacks a membrane on anterior margin of the pronotum (in Allidiostoma the membrane is present), and Parallidiostoma has two well-developed horns on the anterior half of the pronotum (only males are known) (in males and females of Allidiostoma the pronotum is unarmed).

Description. Coleoptera : Scarabaeidae : Allidiostomatinae . Color reddish brown. Form: Body convex oval, length 8.2-8.3 mm. Pygidium not exposed beyond apices of elytra. Head ( Figs. 1–3 ): Surface punctate. Frons convex, armed with median horn. Frontoclypeal suture evident. Eye canthus setigerous; setae moderate in length, thick. Base of declivous anterior edge of clypeus with fringe of short, slender setae. Labrum slightly protruding beyond clypeal anterior margin, small, rounded. Mandibles developed, protruding beyond clypeus and labrum. Maxilary palps with 4 palpomeres. Labium ventrally setose, setae long, slender; labial palps with 3 palpomeres. Antenna with 9 antennomeres, club with 3 small, tomentose antenommeres. Pronotum ( Figs 1–3 ): Surface punctate. Lateral margin weakly serrulate, setigerous; setae moderate to long, inserted in troughs of serrulations. All margins beaded except basal margin on external sides. Disc with deep fovea and horns. Fovea impunctate to punctate; punctures sparse to dense, small to large. Anterior margin of pronotum lacking membrane. Scutellum: Subtriangular , apex slightly rounded. Elytra ( Fig. 1 ): Convex. Surface smooth; with 10 punctate striae, punctures size variable. Lateral margin smooth, setose; setae long. Ve nt e r: Prosternal surface smooth, not setigerous; prosternum setigerous at base and apex, smooth otherwise. Posterior prosternal process long, columnar, slender, setigerous; setae moderately long. Anterior prosternal process produced into rounded, setigerous knob; setae moderate to long. Abdominal sternites narrowed medially, setigerous. Pygidium: Not exposed beyond elytra, surface densely punctate. In lateral view, surface nearly flat. Legs ( Fig. 1 ): Profemur with fringe of long cleaning setae on anterior surface. Protibia with 3 lateral teeth. Mesotibiae and metatibiae with two tranversal carinae, carinae setose; setae thick, moderately long. Tarsal claws simple. Male genitalia ( Fig. 4 ): Symmetrical; parameres longer than phalobase, slender.

Etymology. From the Latin par - meaning similar, in reference to the similarity and close relationship of the genera Parallidiostoma and Allidiostoma . The genus is neuter in gender.

Distribution ( Fig. 5 ). The only known species of this genus is from Cuzco, Peru.

Figures

FIGURES 1 – 3. Parallidiostoma tricornum Ocampo and Colby, new genus and species, dorsal view of the holotype, fronto-dorsal and frontal views of the paratype.

FIGURES 4 – 6. Parallidiostoma tricornum Ocampo and Colby, male genitalia (4); distribution (5); matacoxa (cx) (6 a) and abdominal sternites 1 – 3 (st 1 – st 3), showing the stridulatory organ (arrows) (tr: metatrochanter, fem: metafemur) (6 b).