Description of the immature stages of the flea beetle Omophoita personata (Coleoptera: Chrysomelidae: Galerucinae: Alticini)

. Alticini is the most diverse tribe of Chrysomelidae with approximately 8,000 species. Despite of its high diversity, little is known about their natural history and immature stages. Herein, we describe the immatures of Omophoita personata (Illiger, 1807) reared in laboratory from adults sampled in field. We also investigated and compared with immatures of O. octoguttata (Fabricius, 1775). Detailed morphology and chaetotaxy are presented. Larvae of O. personata have their bodies covered with tubercles and the stemmata are absent. These characteristics are shared with other Oedionychina species, reinforcing the stability of these morphological characteristics as diagnostic of this subtribe. This study provides important descriptive and comparative data that increases the knowledge about Alticini immatures

Alticini's adults have a wide variety of shapes, colors and habits, and species of Oedionychina are among the largest, most colorful, and conspicuous.This subtribe is considered monophyletic and has more than 600 species in 23 genera distributed in the New World, mainly in the Neotropical Region (Ducket and Kjer 2003).They are easily recognized by their smooth or confusedly punctuated elytra, hind legs with femur generally well developed and apical metatarsomere globose (Scherer 1983).Among them Omophoita Chevrolat, 1836 has approximately 134 species distributed mainly in Central and South America (Blackwelder 1944, Scherer 1983, Ducket and Kjer 2003), of which 83 are recorded from Brazil (Linzmeier 2022).
Despite the diversity of this genus, few studies have addressed the natural history of its species or have sought to understand its role in natural environments.A few studies deal with host plants (Begossi andBenson 1988, Jolivet 1991), mimicry complex (Del-Claro 1991), chromosomal characterization (Almeida et al. 2009, 2010, Mello et al. 2014, Rosolen et al. 2018), and just a recently published paper give some data about larval morphology and biological aspects of Omophoita octoguttata (Fabricius, 1775) (Begha et al. 2021).
Therefore, considering the lack of information regarding immatures of this genus, is important to provide such data that can help in the understanding of its evolutionary history, as well as on the economic and ecological aspects of Alticini.Finally, this study aims to describe the external morphology and chaetotaxy of the immatures of Omophoita personata (Illiger, 1807), comparing it with other Alticini species.

MATERIAL AND METHODS
Immatures were obtained from adults sampled in field trips made in 2019 and 2020 at municipality of Realeza (-25.761349, -3.553202), state of Paraná, Brazil and reared in laboratory (26 ± 5 °C; 55-65% humidity, and natural light).The adults (couples) were maintained in transparent plastic containers (1000 ml) with a branch of the host plant -Ocimum carnosum (Spreng.)Link & Otto ex Benth.(Lamiaceae).After oviposition eggs were transferred to a new container with 1 cm of sieved and autoclaved soil (to avoid contamination by pathogens), and slightly moistened with distilled water, since this species pupate inside a cocoon in the soil.Adults and larvae were feed with the host plant and observed daily.
The external morphology of immatures and chaetotaxy were studied using stereomicroscope and microscope.Specimens were measured with a digital pachymeter.The length and width of larvae and pupa were measured in dorsal view immediately after killed.The eggs were measured before they were fixed in alcohol.The mean size is presented followed by the lowest and highest value and the number of specimens measured.
The first and third instars larvae, pupa, as well as some important taxonomic structures, were illustrated in ink using a stereomicroscope, equipped with camera lucida.The illustrations were scanned and vectorized with the Adobe Illustrator and Paint Tool Sai software.The terminology follows Costa et al. (1988) and Duckett and Swigoňová (2002).
Although the material of the three larval instars were available, the description is based on the third instar larva because the first and second instars are very similar to the third.Thus, differences observed among instars are presented in the remarks section.Furthermore, as we had available immatures of O. octoguttata reared in the laboratory they were also analyzed, permitting the direct comparison between species.
Voucher specimens of both species are deposited in the Coleção Entomológica UFFS-RE, of the Universidade Federal da Fronteira Sul, Campus Realeza, Paraná, Brazil.
Coloration.Head and legs black.All thoracic and abdominal segments orange in vivo, cream in AGA.
Abdomen (Figs 10,11).Segments I-VII with three pairs of setae inserted in small tubercles (abs1-3), evenly spaced, with two dorsal pairs and one lateral pair.Segment VIII with two pairs of short setae (abms1-2), thinner than those of the previous segments.Segment IX bearing one pair of urogomphi with apex directed posteriorly; base of each urogomphus with one microseta (abms3).Segments I-V with one pair of annulliform spiracles.
Remarks.The first-instar larva (Fig. 6) of O. personata has differences from advanced larval instars.Beyond the size (body length: 3.62 mm, 3.24-3.99mm, N = 7; body width: 0.76 mm, 0.72-0.89mm, N = 7), the following differences were observed, with characteristics of second and third instars shown between parenthesis: head visible in dorsal view (not visible), pronotum with darker coloration (lighter); prosternum with one pair of median setae (two pairs); mesonotum and metanotum with one pair of egg bursters (egg burster absent), one short bisetose tubercle (met1) in the anterior dorsal row (one pair of short unisetose tubercles in the anterior dorsal row); mesosternum and metasternum with one pair of setae posterior to the bisetose tubercle (one pair of unisetose tubercles posterior to the bisetose tubercle); abdominal segments I-VII with one dorsomedially bisetose tubercle (aat1), followed by one pair of unisetose tubercles (pat1) (one dorsal anteromedially bisetose tubercle, followed by a row of two pairs of unisetose tubercles); segment VIII with one bisetose anteromedially tubercle (aat2) and two posterior unisetose tubercles (pat2) (posterior tubercles bisetose).The second larval instar of O. personata was almost identical to the third instar, with differences in the body size (length: 6.91 mm, 6.00-7.82mm, width: 1.70 mm, 1.60-1.80mm; N = 2).
In general, the main differences from the first to second instar are the loss of egg bursters, replaced by two pairs of unisetose tubercles and the addition of tubercles and setae in the dorsal region of abdominal segments I-VIII.

DISCUSSION
The immatures of Omophoita personata here described and the immatures of Omophoita octoguttata also analyzed are very similar and the larvae cannot be differentiated based on their external morphology and chaetotaxy.Larvae of these species have thoracic and abdominal segments with prominent tubercles and no stemmata.According to Duckett and Swigoňová (2002), such characteristics can be used to distinguish larvae of the Oedionychina subtribe from the other Alticini, since they are found in different species as Walterianella bucki Bechyné, 1956, Alagoasa parana Samuelson, 1985, Alagoasa januaria Bechyné, 1955and Kuschelina gibbitarsa (Say, 1824).The absence of stemmata is pointed out as a characteristic of miner or subterranean species and would also be a characteristic of individuals in the process of recolonizing arboreal environments (Reid 1995, Duckett andSwigoňová 2002).Although O. personata and O. octoguttata feed externally, larvae were found spending much of their time under the soil or protected under leaves, which could, somehow, be related to the absence of stemmata.
The eggs of O. personata are also similar to those of other Oedionychina species, both in their shape and by the fact that they are laid in clusters, with variations only in size.
The first instar larvae of O. personata and O. octoguttata are also similar to those of Alagoasa bicolor (Linnaeus, 1767), A. januaria, W. bucki and Kuschelina bergi (Harold, 1881) (Virkki  and Casari 2002, Cabrera et al. 2016).Omophoita personata, O. octoguttata, A. januaria and K. bergi share egg bursters on meso and metanotum.This feature is absent in W. bucki, and for A. bicolor there is no information about this structure (Virkki and Zambrana 1983).The first instar of the two Omophoita' species can be differed from A. bicolor by the filiform setae in all tubercles (in A. bicolor the setae of the main tubercles are club-shaped) and absence of prothoracic and anal shields (prothoracic and anal shields present in all A. bicolor larval instars); from A. januaria by the head setae filiform (in A. januaria setae of frons and vertex are spatulate); from W. bucki by the digitiform dorsolateral tubercles (in W. bucki the tubercles are large, lobe-like) and presence of filiform setae in all tubercles (in W. bucki the setae are club-shaped).
Regarding the third instar larvae, the two Omophoita' species are very similar to A. januaria in morphology and chaetotaxy.However, in the abdominal segment VIII, that have the same morphology, a difference was found in terminology: the unisetose dorsolateral digitiform tubercles of O. personata were considered as two dorsal unisetose tubercles by Duckett and Swigoňová (2002).Furthermore, in the description of segments IX and X of O. personata, the segment X was considered as being formed by the anal pseudopod.In A. januaria, Duckett and Swigoňová (2002) describe the segment X as being formed by the anal pseudopod and another part with four pairs of setae arranged in a longitudinal row.This row was considered part of segment IX in O. personata as observed in the description of W. bucki (Duckett and Casari 2002) and has three pair of setae.
Comparing O. personata and K. bergi some differences were found such as: 16 unisetose tubercles on pronotum arranged in two rows, the anterior with 12 unisetose tubercles and the posterior with four unisetose tubercles (15 unisetose tubercles on pronotum, nine anterior and six posterior unisetose tubercles in K. bergi), meso and metasternum with a bisetose median anterior tubercle and two unisetose posterior tubercles (two bisetose median tubercles in meso and metasternum in K. bergi), and mandibles with five teeth, one pair of filiform setae and penicillus formed by a row of 14 short and thick setae (mandibles with four teeth, one seta and penicillus formed by two thick setae in K. bergi).More conspicuous differences were observed in relation to Walterianella bucki.Omophoita personata has frons with filiform setae (in W. bucki the setae on frons are stout), filiform setae on pronotum (in W. bucki the pronotal setae are club-like), segment IX with seven pairs of setae arranged closer to each (in W. bucki the pairs of setae are arranged more sparsely), dorsolateral tubercles digitiform (in W. bucki tubercles are much more developed. The pupae of O. personata and A. januaria have similar chaetotaxy of the head and pronotum (mesonotum, metanotum and legs not described by Duckett and Swigoňová (2002), but were illustrated), and those of O. personata can be differentiate by one pair of setae on anterior angles of labrum (absent in A. januaria), segment VIII with two pairs of setae (glabrous in A. januaria), apex of urogomphi directed posteriorly with one pair of microsetae (apex directed inward to the center, glabrous in A. januaria).To K. bergi and W. bucki the pupa's description was not included in the studies (Duckett andCasari 2002, Cabrera et al. 2016), and to Alagoasa bicolor Virkki and Zambrana (1983) shows the development, but also does not describe the morphology.
It is important to mention that comparing larvae and pupa of O. octoguttata with the description presented by Begha et al. (2021), we were able to give complementary information since more detailed data about first and second instar larvae, mouthparts morphology, and pupa chaetotaxy were added.Moreover, some inconsistences related with morphological misinterpretations were also observed.Among them are the position of thoracic spiracles in mesothorax (not in prothorax as reported by the authors) as found in the vast majority of the Coleoptera (Costa et al. 2006), number of antennomeres and palpomeres, two and three respectively (not three and four, respectively), abdominal segments I-VII with two dorsolateral digitiform tubercles and 12 short tubercles (not eight tubercles), 16 filiform setae on pronotum (not ten setae), number of seta on each tubercle, since some are bisetose and other are unisetose (not all tubercles bisetose), and legs chaetotaxy.
Descriptions of immatures of Alticini species (Table 1) that do not belong to the Oedionychina, such as Pseudolampsis darwini (Scherer, 1964), Pseudolampsis guttata (LeConte, 1884), Megistops vandepolli Duviver, 1889 and Distigmoptera borealis Blake, 1943, have more conspicuous morphological differences compared to O. personata.Among them are the absence of prominent tubercles, the presence of sclerites throughout the body, presence of stemmata and distinct chaetotaxy pattern.These characteristics may be related to the environmental niches they occupy and their eating habits (external feeders of Angiosperms, leaf miners, moss inhabiting, etc) reflecting the evolutionary history of these groups, since such species are positioned in different clades within Alticini (Duckett and Kjer 2003).As for larvae, more conspicuous differences are observed between the pupae of O. personata, Pseudolampsis darwini and P. gutatta, which differ in chaetotaxy as well as in the presence of urogomphi (absent is Pseudolampsis' species).The urogomphi are found in O. personata, O. octoguttata and Megistops vandepolli which differs from the Omophoita' species by the urogomphi facing inward, legs glabrous and body covered with more setae.
Not all species addressed in this study have the pupa described.The lack of information and incomplete or superficial descriptions may be due to the lack of specimens in pupal stage, the difficulty of finding them in nature, conservation of the material and the disregard of pupae' characteristics for species characterizations.
Overall, the immatures of O. personata and O. octoguttata, as well as the other immatures of Oedionychina, have very similar morphological characteristics, reinforcing the morphological stability of immatures of this group.These immatures