Rearrangements in some species groups of Amblycerus Thunberg, 1815 (Coleoptera: Chrysomelidae: Bruchinae) including keys, description of a new species, new host plant and distributional records

Abstract

Encompassing 39 species groups, Amblycerus Thunberg, 1815 is the second most diverse genus of seed-beetles in the Americas. Considering that the delimitation of some of the included species-groups is incongruent in the literature, this work tackled one particularly problematic group, the dispar group, which includes species that, depending on the classification scheme, have been classified in two other groups, namely the spondiae and alternatus groups. We recognize six valid species in the dispar group, viz. A. dispar (Sharp, 1885), A. crassipunctatus Ribeiro-Costa, 1999c A. insuturatus (Pic, 1902), A. schwarzi Kingsolver, 1970, A. taeniopygus Ribeiro-Costa, 1999 c, and Amblycerus goianiensis Santos & Ribeiro-Costa, sp. n., and four in the spondiae group, viz. A. spondiae Kingsolver, 1980, A. cuernavacensis Romero, Johnson & Kingsolver, 1996, A. vitis (Schaeffer, 1907) and A. alternatus (Pic, 1954). Three species are excluded from their original groups, namely A. eustrophoides (Schaeffer, 1904), A. serieguttatus (Chevrolat, 1877), from the alternatus group, and A. simulator (Jacquelin DuVal, 1857), from the dispar group, all considered here as incertae sedis. The remaining species of the alternatus group, A. schwarzi and A. alternatus, are transferred to other previously mentioned groups, thus dissolving this group. We provide diagnoses for the 13 species studied, redescribe three species, and describe one new species. Color illustrations of the dorsum and pygidium, drawings of the male genitalia and geographic distribution maps are included. Identification keys are also added for the dispar and spondiae groups. We record new host plants for four Amblycerus species and new localities for five species. The plant taxa Sarcomphalus mistol (Griseb.) Hauenschild, Terminalia corrugata (Ducke) Gere & Boatwr., T. tetraphylla (Aubl.) Gere & Boatwr. and Rhus virens Lindh. ex A. Gray var. choriophylla (Wooton & Standl.) L. D. Benson are first registered here as hosts of Amblycerus. Four new records for Amblycerus, namely Capparis, Neopringlea, Rhus and Sarcomphalus, and two new records at the family level, Capparaceae A. Juss. and Salicaceae Mirb., the latter also being a new record for Bruchinae.

Unusual host selection inAmblycerus disparlarvae (Coleoptera: Chrysomelidae: Bruchinae) and its potential impact on stored almonds (Prunus dulcis)

“…With 120 species, the genus Amblycerus Thunberg is the second largest American genus of Bruchinae after Acanthoscelides (Dos Santos and Ribeiro-Costa, 2019; and references therein). The genus is distributed from southern Canada to central Argentina (Romero et al ., 1996) and central Chile.…”

“…The genus is distributed from southern Canada to central Argentina (Romero et al ., 1996) and central Chile. The species herein studied [ Amblycerus dispar (Sharp)] is currently included in the dispar species group which has been recently re-defined by Dos Santos and Ribeiro-Costa (2019). These authors also provided a diagnosis, description of the adult, and a dichotomous key to the recognition of its species within the group.…”

“…Their results show that even if Fabaceae seems to be the ‘original’ host some species have been able to colonize others. In this regard, Dos Santos and Ribeiro-Costa (2019) cite 14 plant families that have been associated with Amblycerus . According to them, the dispar species group also has a wide host association including ten plant species in eight families (Anacardiaceae, Combretaceae, Euphorbiaceae, Fabaceae, Humiriaceae, Rhamnaceae, Verbenaceae, and Rubiaceae).…”

“…Besides G. decorticans , Sarcomphalus mistol (Griseb.) Hauenschild, Ziziphus joazeiro (Rhamnaceae), and Spondias tuberosa Arruda (Anacardiaceae) also have occasionally been associated with A. dispar feeding behavior (Dos Santos and Ribeiro-Costa, 2019). Furthermore, González et al .…”

“…Dos Santos and Ribeiro-Costa (2019) provide the following diagnostic characters for A. dispar ; eyes closer to each other anteriorly, ocular index: 9.5; median lobe of male genitalia about 4.5 times as long as its greatest width at apical region and internal sac at the apical region without sclerites. This species can be discriminated from related taxa of the species group by the following combination of morphological features: pronotum and elytra covered with yellowish or orange setae (fig.…”