Acanthoscelides quadridentatus

(Schaeffer, 1907)

Acanthoscelides quadridentatus is a seed beetle (Bruchinae) native to the Americas with introduced in Australia and southern Asia. In its native Brazilian Cerrado range, it exhibits phenotypic plasticity with two distinct morphs: melanic individuals that are approximately 1.1-fold larger, and lighter, smaller individuals. The is a seed of Mimosa setosa, attacking both M. setosa var. paludosa and M. setosa var. setosa. Attacked seeds fail to germinate, making this a significant mortality factor for its plant.

Pronunciation

How to pronounce Acanthoscelides quadridentatus: /əˌkænθoʊˈskɛlaɪdiːz ˌkwɒdrədɛnˈteɪtəs/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from congeneric by association with Mimosa setosa plants in its native range. The melanic morph can be separated from the lighter morph by darker coloration and larger body size (approximately 1.1-fold difference). Specific diagnostic morphological features require examination of genitalia or other detailed characters not described in available sources.

Appearance

exhibit color with two distinct morphs: a melanic (dark) morph and a lighter-colored morph. Melanic individuals are approximately 1.1 times larger than lighter morphs. As a member of Bruchinae, adults likely have the characteristic compact, oval body form and short, clubbed typical of seed beetles.

Habitat

Brazilian Cerrado savanna; specifically associated with plant Mimosa setosa in this . Introduced occur in other regions but specific details for these are not documented in available sources.

Distribution

Native to the Americas (North America, Middle America, South America); introduced to Australia and southern Asia. Specifically documented from the Brazilian Cerrado where it attacks Mimosa setosa.

Diet

Seeds of Mimosa setosa (Fabaceae: Mimosoideae), including both M. setosa var. paludosa and M. setosa var. setosa. Attacked seeds do not germinate, indicating complete consumption or destruction of the embryo.

Host Associations

Mimosa setosa var. paludosa - seed Seeds attacked by ; attacked seeds fail to germinate
Mimosa setosa var. setosa - seed Seeds are 1.9-fold heavier than var. paludosa; attacked seeds fail to germinate

Behavior

Exhibits phenotypic plasticity in body size correlated with color morph: melanic individuals are larger than lighter morphs. No difference in attack rate between morphs on seeds has been observed. The thermal melanism hypothesis is supported for the melanism-size relationship, though melanic individuals do not show increased foraging activity.

Ecological Role

Seed ; causes complete seed mortality in attacked Mimosa setosa seeds. Acts as a significant mortality factor for plant in the Brazilian Cerrado.

Human Relevance

Potential agricultural pest of Mimosa ; introduced in Australia and southern Asia may impact native or cultivated legumes, though specific economic impacts are not documented in available sources.

Similar Taxa

Acanthoscelides winderiSympatric congeneric also attacking Mimosa setosa var. paludosa in the Brazilian Cerrado; requires detailed morphological examination for separation

More Details

Phenotypic plasticity

The demonstrates phenotypic plasticity with two distinct morphs. Melanic individuals are larger but do not show increased foraging activity as predicted by the thermal melanism hypothesis, suggesting that factors beyond may influence morph expression.

Seed weight and host variety effects

Seeds of M. setosa var. setosa are 1.9-fold heavier than those of var. paludosa and germinate faster with higher success rates when intact. However, both varieties suffer complete germination failure when attacked by A. quadridentatus.