Pelidnota granulata (Gory, 1834) (Coleoptera, Scarabaeidae, Rutelinae): description of the pupa and new records from Amazonas state, Brazil

The Neotropical ruteline genus Pelidnota MacLeay currently includes 194 species and subspecies with a few described preimaginal stages. Here we describe the pupa of Pelidnota granulata (Gory, 1834), provide illustrations, comparative notes on other known pupae of Rutelini and comments on its geographical distribution. The key to known pupae of Rutelini is updated. Key-Words. Amazon; Neotropical; Immature; Chafers; White grub.


INTRODUCTION
The genus Pelidnota MacLeay (Coleoptera: Scarabaeidae: Rutelinae: Rutelini: Rutelina) currently includes 194 species and subspecies distributed in the New World (Moore et al., 2017). This genus is diagnosed by the clypeus not fused to the labrum, outer margin of mandible with two reflexed teeth, apex of elytra with no spiny projections, pronotum with anterior margin completely beaded, prosternal process produced to level of procoxae, apex of thoracic ventrite process anterior to mesocoxae, metatibia not laterally flattened, and metatarsus as long as metatibia or almost so (Soula, 2006;Moore et al., 2017).
Here we describe the pupa of Pelidnota granulata based on one female pupa and one reared male adult and give additional locality records in Amazonas state, Brazil. The preexisting identification key to known Rutelini pupae is updated.

MATERIAL AND METHODS
Two pupae of P. granulata were collected in a decaying trunk in Museu da Amazônia (MUSA) (Manaus, Amazonas state, Brazil). One male pupa was reared to adult, and one female pupa was killed in boiled water and conserved in 80% ethanol. The reared adult was identified based on Bouchard (2003) and Soula (2006Soula ( , 2010 The images were taken using a Leica DFC295 camera attached to a Leica M165C stereomicroscope and were processed using the Leica Application Suite (LAS) software version 4.1. Plates were made using Adobe Photoshop software. The photographic illumination follows Kawada & Buffington (2016).

Remarks:
Of the 21 species of Rutelini with known pupae, Pelidnota granulata pupae are similar to the pupa of Homonyx chalceus Blanchard, 1850 and its congener Pelidnota lugubris LeConte, 1874. Those species have a similar general body shape, femur-tibia articulations exposed in dorsal view, five pairs of dioneiform organs, abdominal spiracle I exposed, and abdominal tergite IX fold densely setose. Pupae of P. granulata are distinguished from them by (characters of 1 = H. chalceus and 2 = P. lugubris pupae given in brackets): 1) pronotum with ecdysial longitudinal line distinct (1 = ecdysial longitudinal line indistinct; 2 = as P. granulata); 2) medial area of mesonotum as long as wide, with posteromedial margin narrowly rounded and not extending to anterior margin of abdominal tergite I (1 = as P. granulata, but posteromedial margin broadly rounded; 2 = medial area longer than wide, posteromedial margin truncated and extending to anterior margin of abdominal tergite I); 3) posterior margin of metanotum almost straight and with a medial lobe (1 = posterior margin of metanotum multisinuous and without median lobe; 2 = posterior margin of metanotum trapezoidal and without median lobe); 4) dioneiform organs between abdominal tergites I-II well defined (1 = as P. granulate; 2 = barely defined). As pointed out by Morón (1993), ethologic characters such as ecdysis, pupation location of the third instar larvae are important sources of taxonomic and phylogenetic information. The observed pupal chambers of P. granulata is oblong and about 1.3 times wider than pupae, internally covered with compressed sawdust (Fig. 2) and locate in the sapwood section of the decaying trunk, where the decomposition class was between CD2 and CD3 according to the classification scheme used in Alencar et al. (2020). The dorsal ecdysial opening of the last instar larva is almost equal to the larval body length and the pupa stays partially covered by last larval cast skin (Fig. 2). Similar habits are also observed in Lagochile emarginata (Gyllenhal, 1817) (cf., Albertoni  Morón (1993) to be diagnostics for Rutelinae (Anomalini and Rutelini). In opposition, in Melolonthinae the larval exuvia is positioned at the posterior region of the abdomen of the pupa, and in third instar larvae of Dynastinae (Dynastini and Oryctini) the ecdysial opening occupies only half of the body length (cf., Morón 1993: figs. 8-11). Gory (1834) described P. granulata from Cayenne, French Guiana, and was reported in Demerara, Guiana by Ohaus (1912). Moore et al. (2017) reviewed the distribution of the pelidnotine species based on literature and recorded P. granulata to Brazil.
The distributional data presented here update the occurrence register of the species. This species is known to occur in Brazil, French Guiana, and Guiana.