Cyclocephala melanocephala (Fabricius, 1775)

Rodrigues, Sérgio Roberto, Barbosa, Carlos Aparecido Ferreira, Fuhrmann, Juares & Amaro, Ricardo Aparecido, 2018, Mating behavior and description of immature stages of Cyclocephala melanocephala (Fabricius, 1775) (Coleoptera: Scarabaeidae: Dynastinae), identification key and remarks on known immatures of Cyclocephalini species, Revista Brasileira de Entomologia 62 (3), pp. 205-219 : 207-214

Cyclocephala melanocephala (Fabricius, 1775)

Third instar larva ( Figs. 5–44 ). Body ( Fig. 5 ) length: 19–26 mm; grayish or yellowish white, head and respiratory plates yellowish brown; surface densely setose, setae yellowish brown to brown. Head ( Figs. 6 , 7 , 13) width: 2.8– 3 mm; epicranial and epistomal sutures distinct; stemmata very small; antennifer somewhat cylindrical and with 3 punctures; cranium, clypeus and labrum ( Figs. 7, 8 ) with many homogeneously distributed punctures, except in labral anterior area. Each half of cranium and clypeus with ( Fig. 7 ): 4–3 long and 2–3 min dorsoepicranial setae (des) in a row and 1 min seta internally positioned, 2 long and numerous minute posteroepicranial setae (pes), 2–3 long anteroepicranial setae (aes), 5–8 long externoepicranial setae (ees), 2–3 long and 1 min posterofrontal setae (pfs), 1 long externofrontal seta (efs), 2–3 long anterofrontal angle setae (aas), 2 long anterofrontal setae (afs), 2 long externoclypeal setae (ecs), 1 long anteroclypeal seta (acs). Labrum ( Fig. 8 ): each half with 2–3 long and 1 min posterolabral setae (pls), 1 long mediolabral seta (mls), 4–5 long laterolabral setae (lls), 2 long anterolabral setae (als). Antenna with 4 antennomeres ( Figs. 9–12 ): I short (length/larger dorsal width = 2.1) and with 5 sensilla (1 dorsal, 1 internal, 1 external, 2 ventral); II long (l/w = 2.3–2.5) and with 9–10 sensilla (3–4 dorsoproximal, 2 ventroproximal, 4 ventrodistal); III short (l/w = 1.3) and with 10 sensilla (2 dorsoproximal, 2 internal, 4 external, 2 ventral), ventrodistal process bearing a dorsal sensorial spot and 2 distal sensilla; IV long (l/w = 2.8), with 6 sensilla (4 external, 2 ventral), 2 dorsal and 2 ventral sensorial spots, and a distal sensorial area bearing about 9 prominent minute sensilla. Epipharynx ( Figs. 15, 16 ). Corypha : epizygum distinct and clythra absent. Haptomerum: zygum beak-like, 2-toothed and with about 10 sensilla; heli absent. Paria: acroparia evidently separated from chaetoparia and each side with about 13 setae; each side of acanthoparia with 9–11 anterior setae and 8–9 min posterior setae; gymnoparia narrow; right chaetoparia with about 95 setae, left chaetoparia with about 70 setae; dexiotorma twice long than laeotorma, left pterotorma rounded, aptorma indistinct, epitorma as an impressed rounded sulcus; plegmatia, proplegmatia and phoba absent. Pedium longer than wide and smooth. Haptolachu s with right area bearing 8 setae and 2 sensilla and left area bearing 12 setae and 2 sensilla; nesium internum (sensorial cone) tubercle-like and with 4 sensilla; nesium externum (sclerotized plate) prominent and acute; crepis lateral area conspicuous and medial area indistinct. Mandible ( Figs. 17–22 ). Right incisor with 3 teeth, left incisor with 2 conspicuous teeth; incisor dorsoproximal area with 2 setae and 2 punctures. Ventral striated stridulatory area with 22–23 thin anterior striae and 6 broad posterior striae. Ventral area with 4–6 medial punctures and posterior asperites. Scrobe (externoproximal area) with about 7 setae. Ventral processes well developed. Right molar with 9 dorsoproximal setae in a row, 7 ventroproximal setae in a tuft; 4 chisel-like teeth; calx small; brustia with 6 setae. Left molar with 9 dorsoproximal setae in a row, 3 ventroproximal setae in a tuft; 2 anterior chisel-like teeth transversally positioned to each other, a dorsal and a ventral tooth, 2 transversal shallow carinae between the dorsal and ventral teeth; acia with apex rounded and bearing about 6 setae; calx semicircular; brustia with 12 setae. Maxillae ( Figs. 23–25 ). Galea and lacinia separated by suture; galea with an uncus; lacinia with 3 unci; mala without conspicuous setae row. Stipe with stridulatory area bearing 13 obtuse teeth and a distal truncate process. Palp with 4 palpomeres: I with an externoproximal sensillum and a minute externodistal seta; II with an externodorsal sensillum and 3 ventral sensilla; III with an external seta, a ventral seta and 2 ventral sensilla; IV with 3 external sensilla and an internodistal minute seta, distal sensorial area bearing about 13 sensilla. Hypopharynx ( Figs. 16 , 24 ) with asymmetrical sclerite, right and left lateral with about 14 setae (7 long, 7 min), lateromedial left area with a row of about 22 stout setae, lateromedial right area with a group of phobae; right anterior area with a prominent tooth, posterior area with a prominent semispherical process. Posterior preoral area: each side of dorsal area (posterior to epipharynx, Fig. 15 ) with a sensillum; each side of ventral area (posterior to hypopharynx, Fig. 24 ) with 2 sensilla, right area with an anterior stout seta, left area with a row of about 23 stout setae. Labium ( Figs. 16 , 24, 25 ). Submentum with a posterior sclerite bearing 1 setae and 4–5 sensilla on each side, anterior area with 2 setae and a sensillum on each side. Mentum with a glabrous sclerite medially interrupted, anterior area with 7–8 setae and 1–4 sensilla on each side. Prementum with a sclerite bearing 6–8 setae distributed around palpi insertion; ligula ( Figs. 16 , 24 ) with 3 large medial setae on each side, 16 small posterior tooth-like setae, a small medial tubercle-like process, a posterior transversal sclerite, posterior area bearing asperites. Palp with 2 palpomeres: I with a minute ventroproximal seta; II with a ventrodistal sensillum, distal sensory area with about 13 sensilla. Thorax ( Figs. 5 , 14). Prothorax with a tergal lobe bearing 40–50 thin setae (setae similar to

210 S.R. Rodrigues et al. / Revista Brasileira de Entomologia 62 (2018) 205–219

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medial ventral lobe with 5–7 thin setae, posterior ventral lobe bare. Abdominal segment VIII similar to VII, but tergal lobe with 25–28 thin setae. Abdominal segment IX with a tergal lobe with an anterior group of 10–15 thin setae and a posterolateral group of 21–24 thin setae, a pleural lobe with 14–17 thin setae, anterior ventral lobe bare, posterior ventral lobe with 4 medial thin setae and 2–4 lateral thin setae. Segment X ( Figs. 5 , 14, 43 ) with a curved anal opening, tergite with an anterior U-shaped sclerotized thin bar, a group of about 170–180 anterior thin setae and a posterior group of 46–61 stout setae; ventral anal lobe with 10–15 thin setae and 28–34 hamate setae. Spiracles ( Figs. 35–42 ): I smaller than other ones and with 6–8 perforations in DR and LR, and 13–15 in VR; II–VI similar to each other and with 9–13 perforations in DR, 8–11 in LR, 12–16 in VR; VII–VIII similar to each other, wider than other ones, number of perforations of VII similar to II–VI, VIII with 11–13 perforations in DR, 9–11 in LR, 16–20 in VR; bulla I strongly narrower than the distances between respiratory plate arms, II–VII slightly narrower than the distances between respiratory plate arms, VIII as wide as the distances between respiratory plate arms. Each side of the raster ( Fig.43 ) with: tegillum with 1–3 acute setae ( Fig.44d) and 8–11 hamate setae ( Fig. 44b), of which 1–2 hamate setae are preseptular setae (anterior to the palidia); barbula indistinct; palidium with 3–4 short bifurcate setae ( Fig. 44a); septula irregular shaped and barely distinct.

Remarks. Larvae of C. melanocephala and C. paraguayensis are easily distinguished from other known Cyclocephalini larvae by the presence of palidia with bifurcate setae ( Fig. 44a). The body chaetotaxy ( Table 1) is useful as supplementary data to the species identification.

For C. modesta and C. putrida , only the raster is known. Morelli (1991) provided images of these species, raster and attributed the original data to an unpublished thesis: “L. Alvarado. 1980. Sistemática y bionomía de coleópteros que en estados inmaduros viven en el suelo. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo, Argentina ”. Larvae of C. modesta have a peculiar raster (not seen in other Cyclocephalini ) with palidia long and posteriorly divergent. Otherwise, larvae of C. putrida cannot be distinguished from other Cyclocephala larvae as the raster do not show any specified pattern. More data about both species are needed to clarify the larvae taxonomy.

Third instar larvae of C. flavipennis and C. signaticollis Burmeister, 1847 are easily differentiated from other Cyclocephalini larvae by ventral anal lobe ornamentation, both have posteromedial hamate setae distinctly bigger than anterolateral setae. Immature of C. signaticollis was described by Remedi-de-Gavotto (1964) and redescribed by Morelli (1991), and larvae of C. flavipennis were first time characterized by Pereira and Salvadori (2006). Until now, it is impossible to separate both species and more studies are needed to solve this problem.

The dorsolateral macula of meso- and metafemur was not noted in other Scarabaeoidea larvae. A similar modified area was described in Bubas bubalus (Olivier, 1811) posterior leg ( Scarabaeinae ; Paulian and Lumaret, 1972). However, the maculae of B. bubalus has a minute seta and two slightly globose dark spots (maculae smooth in C. melanocephala ).

Material examined. Brazil, Mato Grosso do Sul, Cassilândia , experimental farm of UEMS, 20.v.2016 , leg. R. A. Amaro, 6 larvae ( MZSP – 10.356) .

rounded in females ( Fig. 50 ); precoxal area hidden by the head in ventral view. Mesonotum as long as pronotum and longer than metanotum. Elytra curved ventrally around the body and almost smooth. Pro-, meso- and metacoxa contiguous; profemur-tibia slightly exposed in dorsal view; mesofemur-tibia superposed to wings in ventral view and hidden in dorsal view; protibia with

Figures

Figs. 5–6. Cyclocephala melanocephala, third instar larva; 5, lateral; 6, head, dorsal. t10, abdominal tergite X; usb, U-shaped sclerotized bar. Scale= 1 mm.

Figs. 7–12. Cyclocephala melanocephala, third instar larva; 7, cranium and clypeus,dorsal; 8, labrum, dorsal (epipharyngeal ventral setae omitted); 9–12, left antenna (dorsal, internal, external, ventral; external and internal sides with apex detail; some sensilla numbered to easily the correspondence; sensillum h can be absent).Chaetotaxy (italic) on the text. Scale= 0.5mm (antennal details with magnification four times bigger than antennae).

Figs. 15–16. Cyclocephala melanocephala, third instar larva; 15, epipharynx; 16, cibarium. aca, anterior most acanthoparia seta; acr, lateroposterior acroparia seta; crp, right part of crepis; lip, ligular tubercle-like process; ppa, posterior preoral area. Scale= 0.5mm.

Figs. 17–22. Cyclocephala melanocephala, third instar larva; 17–19, right mandible (ventral, internal, dorsal); left mandible (dorsal, internal, ventral). Scale= 0.5mm.

Figs. 23–25. Cyclocephala melanocephala, third instar larva; 23, maxilla, internal; 24, maxilla, hypopharynx, ligula, dorsal; 25, maxilla, labium, ventral. ppa, posterior preoral area. Scale=0.5 mm.

Figs. 43–44. Cyclocephala melanocephala, third instar larva; 43, raster; 44, setae detail; a, pali; b, hamate setae; c, short setae; d, long setae. Scale, Fig. 43 = 1 mm; Fig. 44 = 0.5mm.

Figs. 26–42. Cyclocephala melanocephala, third instar larva; 26–28, right legs and pleurites (anterior, medial, posterior); 29–31, right pro-, meso- and metapretarsus, dorsal; 32–33, detail of perforations of mesothoracic spiracle (dorsal arm,medial area); 34–42, mesothoracic spiracle and abdominal spiracles I–VIII.Scale, Fig.26 = 0.3mm; Figs.29, 34 = 0.1mm; Fig. 32 = 0.05 mm.

Figs. 48–51. Cyclocephala melanocephala, pupa; 48, head, frontal; 49–50, prosternal posterior process (male, female); 51, male terminalia, ventral. Scale= 2 mm.