First report of immatures of Cryptocephalus Geoffroy, 1762 (Coleoptera: Chrysomelidae) from Brazil with notes of its bioecology on Wedelia goyazensis Gardner (Asteraceae) and synthesis of the genus occurrence records in Brazilian territory

Cryptocephalinae and Lamprosomatinae form the Camptosomata clade within Chrysomelidae and are defined by the behavior of building fecal shelters for and by their offspring (‍Erber, 1988). The female holds the naked egg with the posterior legs and rotates while covering it with fecal plates to form, after up to half an hour, a capsule; the immature hatches, breaks the maternal seal and expands that first protection with its own feces while developing until reaching the adult stage (‍Brown & Funk, 2005).

Chryptocephalini has the smallest representatives and concentrates 3500 of the 5300 species of the subfamily; only in the genus Cryptocephalus Geoffroy, 1762 (Chrysomelidae: Cryptocephalinae) there are at least 1700 species described (‍Chamorro, 2014).

Cryptocephalus species can be found feeding on flowers, such as Asteraceae (‍Baselga & Novoa, 2000; ‍Lencina Gutiérrez et al., 2007). However, even though it is a cosmopolitan genus and there is knowledge of immatures of at least 106 species, there is not a single record of immature stages of this genus in Brazil (‍Chaboo et al., 2016).

Here we present the first report of immature stages of Cryptocephalus from Brazil with some notes of its bioecology on the host plant. We also compile Cryptocephalus occurrence records in Brazil from the recent literature.

Adult beetles were collected on Asteraceae inflorescences at A.C. Simões Campus, Federal University of Alagoas (-9.557309, -35.775158), in September 2018. Adults were taken to the laboratory together with the inflorescences of Asteraceae to document bioecological aspects. Sexing was performed by observing copulation. Rearing was carried out to obtain juveniles, with inflorescences being replaced daily (24,7-26,8 ºC and 51-‍72 % RH; photoperiod 12:12 h). To avoid predation, the rearing proceeded with the removal of any other insect from the collected fresh inflorescences, which were immersed in water, with one drop of detergent to break its tension, for 12 hours before being used for food replacement. Digital photographs of the plant and the beetle were taken; and morphometric measurements were performed. Beetles and host plant have been identified by specialists, respectively, Dr. Davide Sassi (Università degli Studi di Milano) and Dr. Mara Angelina Galvão Magenta (Universidade Santa Cecília). Beetle voucher specimens will be deposited in the Padre Jesus Santiago Moure Entomological Collection, Federal University of Paraná; plant exsiccates was deposited at the Herbarium-MAC, Environmental Institute of Alagoas, under registration 65501.

The beetle was identified as belonging to the genus Cryptocephalus; the female (≈ 2 mm) being larger than the male (≈ 1.6 mm) (Fig. 1). The plant is Wedelia goyazensis Gardner (Synonyms: Aspilia ramagii Ridl.; Seruneum goyazense (Gardner) Kuntze; Wedelia alagoensis Baker; Wedelia hookeriana Gardner; Wedelia ramagii (Ridl.) J.U. Santos; Wedelia villosa Gardner) (Asteraceae) (Fig. 2).

In the field, adults were observed copulating on tubular flowers (Fig. 3) or hidden on the ligulate flower axils or sepal axils. During rearing, adult Cryptocephalus fed on petals of tubular flowers of W. goyazensis (Fig. 4), never on ligulate ones, causing damage to the floral tube. Females oviposit on sepal axils and on ligulate flower axils (Fig. 5). At the end of covering the egg with fecal plates, the female gives a slight kick to the fecal capsule, throwing it back. Eggs do not have a chorionic stem and can be found on ligulate flower axils or sepal axils. No eggs were seen on tubular flowers. After hatching, the larvae look for tubular flowers to feed on pollen, often entering almost entirely into the floral tube (Fig. 6), and may go unnoticed in a superficial search.

Laboratory observations showed that adults and nymphs of pirate bug (Hemiptera: Anthocoridae) forage quickly on inflorescences of W. goyazensis, finding Cryptocephalus egg capsules and newly hatched larvae which they handled with their front legs. Eggs resist this attack, but the newly hatched larvae are preyed upon.

Wedelia goyazensis is a shrub endemic from Brazil, with prevalent occurrence in the phytogeographic domain of the Caatinga, northeast region (‍Alves & Bringel Jr., 2020). Immatures of Cryptocephalus were registered only once feeding on an Asteraceae (‍Paulian, 1953), but there are no other reports of Asteraceae flowers as food.

There are 18 published records of Cryptocephalus in Brazil (Table 1), four of them in the northeast (‍Bryant, 1954; ‍Harley et al., 1995; ‍Guedes et al., 2019; ‍Rafael et al., 2020). However, they only offer superficial information. Only one (‍Guedes et al., 2019) presents habitat data, but no information regarding host plants or bioecology. It is worth noting that we did not compile data from museum collections, which should be consulted for a more complete overview of the distribution of the genus in Brazil.

Cryptocephalus is one of the most species-rich genera within the animal kingdom (‍Sassi, 2006). However, many descriptions need to be revised since there is a numerous history of taxonomic errors (‍Schöller, 2002). Very little is known about the biology of this genus in Brazil and this new information can help improve species recognition.