Stolas aenea ( Olivier, 1790 )

Leocádio, Michele & Mermudes, José Ricardo M., 2019, Description of immatures of Stolas aenea (Olivier, 1790) and Stolas nudicollis (Boheman, 1850) (Coleoptera: Chrysomelidae: Cassidinae: Mesomphaliini), Zootaxa 4545 (1), pp. 61-76 : 62-66

Stolas aenea ( Olivier, 1790)

( Figs 1‒2 , 4‒37 )

Biology. First instar larvae showed gregarious behavior ( Fig. 1 ). All instars carried fecal material and exuviae of previous instars on the supra-anal process.

Host plant. New host plant feeding record for Mikania sp. 1 ( Asteraceae ) ( Fig. 3 ). Ipomoea batatas (Convolvulaceae) was previously recorded as host plant of S. aenea ( Silva et al. 1968) .

First instar larva. Measurements (mm). (n = 2). Body length: 1.1‒1.6 (mean = 1.4); body width: 0.5; head width; 0.4‒0.5 (mean = 0.5); supra-anal process length: 0.8‒1.0 (mean = 0.9).

Body ( Figs 4‒5 , 12‒13 ) elongate, slightly flattened dorsoventrally, widest across the metathorax; with 14 pairs of lateral scoli and a pair of supra-anal processes. Integument pale yellow. Meso- and metanotum with pale brown spots. Pronotum, lateral scoli, supra-anal processes, spiracles and legs, brown. Head dark brown. Body surface granulose.

Head ( Figs 6‒7 , 14 ) strongly sclerotized and hypognathous. Endocarina complete, connected to fronto-clypeal suture. Antennae short ( Fig. 15 ), set in membranous ring, and two-segmented: first antennomere cylindrical, wider than long with two campaniform sensilla; second antennomere cylindrical, length subequal to width, with five peglike sensilla and one long sensory appendix at apex. Vertex with four lateral minute setae. Frons with five rows of very long setae: row Fa with three setae, Fb with four setae, Fc with three setae, Fd with one seta and Fe with two setae. Tempora with four long setae. Six paired prominent stemmata laterally. Clypeus transverse ( Figs 6 , 16 ), five times wider than long, with pair of lateral setae and sensilla. Labrum ( Figs 8 , 16 ) two times wider than long, with four long setae and two campaniform sensilla, anterior margin slightly emarginated, with two setae laterally and two campaniform sensilla medially. Epipharynx ( Fig. 9 ) medially with two short setae and five pairs of rounded sensilla: three campaniform sensilla and two larger sensilla with four spots inside; anterior margin with six robust setae on each lateral and eight short setae on emargination. Mandibles ( Figs 10‒11 , 17 ) strongly sclerotized, with four distinct triangular teeth with serrated internal margin and one proximal rounded tooth; dorsally with two long setae at the base and two medially sensilla. Maxillae and labium ( Figs 7 , 18 ) connate. Maxillary palpi ( Fig. 19 ) two-segmented, with a distinct palpiger. First palpomere with two setae and one campaniform sensillum ventrally, second palpomere conic and rounded at apex, with group of apical sensilla, one seta and one campaniform sensillum dorsally. Mala and lacinia ( Fig. 19 ) not distinctly delimited from palpiger. Palpiger with two long setae and two campaniform sensilla ventrally. Lacinia on dorsal side of palpiger bearing spines at apex. Mala with nine stout, pointed setae and one campaniform sensillum. Paired stipes each with three long, pointed setae. Labial palpi ( Fig. 20 ) one-segmented with group of apical sensilla and one campaniform sensillum laterally. Prementum with two long setae, two short setae and two campaniform sensilla. Postmentum with three pairs of long setae.

Thorax. Pronotum ( Figs 21‒22 ) with ten pairs of very long setae, the posterior ones bifurcated at apex. Meso- and metanotum ( Fig. 23 ) with some setae bifurcated or spatulated at apex, distributed uniformly, remaining setae pointed at apex. Mesonotum with two rows of protuberances: first row with eight protuberances bearing one seta each; second row with six protuberances with ten setae disposed as 2-1-2-2-1-2. Metanotum ( Fig. 23 ) with two rows of protuberances: first row with four protuberances bearing one seta each, second row with six protuberances with ten setae disposed as 2-1-2-2-1-2. Meso- and metanotum with lateral protuberances usually bearing two setae, one short and one long. Legs stout ( Fig. 24 ), three-segmented; coxa with three very long setae and about seven short setae. Femur strongly sclerotized, with about eight long setae; proximally, two short setae and five campaniform sensilla. Tibiotarsus with single claw at the apex, with numerous stout, spatulated setae concentrated apically.

Lateral scoli unbranched ( Fig. 25 ), with numerous long pointed setae along its length and one seta at apex. Four pairs of scoli on prothorax, one pair on mesothorax, one pair on metathorax and one pair on abdominal segments I‒VIII. Scoli of pairs IX‒XI shortest, XIII‒XIV longest. All shorter than supra-anal processes.

Abdomen with ten segments ( Fig. 26 ). Abdominal tergites I‒VIII with one pair of prominent lateral spiracles ( Fig. 27 ), their diameter slightly decreasing posteriorly. Abdominal tergites with rows of ten long setae each and one short seta close to spiracles. Ventral surface ( Fig. 28 ) with shorter setae on sternites I‒IV, sternites V‒VIII with setae as long as tergite setae. Supra anal-processes unbranched ( Fig. 29 ), with numerous long setae, like lateral scoli, and some setae spatulated; apex unarmed.

Last instar larva. Measurements (mm). (n = 2). Body length: 7.4‒9.2 (mean = 8.3); body width: 4.8‒5.8 (mean = 5.3); head width: 1.9‒2.1 (mean = 2.0); supra-anal process length: 2.0.

Body ( Figs 30‒31 ) oval, flattened dorsoventrally; widest across the metathorax and first abdominal segment; with 14 pairs of lateral scoli and a pair of supra-anal processes.

Dorsal side pale yellow, with brown spots regularly distributed and many short setae uniformly distributed. Meso- and metanotum with distinct brown spots, darker than spots on pronotum. Abdominal tergites I‒II with two lateral brown spots, tergites III‒IV with four brown spots, tergites V‒VIII with two lateral brown spots and two medial pale brown spots. Head, legs and lateral scoli yellowish-brown, except for scoli VI‒VIII, yellow at the base. Pair of supra-anal processes with basal two-thirds yellow, apex brown. Ventral surface brown with an oval pale yellow inner region; pale brown parts with rugose surface and pale yellow parts with smooth or rugose surface.

Head ( Fig. 32 ) strongly sclerotized, hypognathous and dorsally covered by pronotum, visible only ventrally. Endocarina complete, connected to fronto-clypeal suture. Antennae short, set in membranous ring, and twosegmented: first antennomere cylindrical, wider than long; second antennomere cylindrical, longer than wide with several extremely small peg-like sensilla and one sensory appendix at apex. Vertex with four lateral minute setae. Frons with around 17 pairs of long setae distributed uniformly. Tempora with five long setae. Six lateral prominent stemmata, two grouped pairs positioned lateral-frontal and one pair ventral-lateral. Clypeus transverse ( Fig. 32 ), four times wider than long, with pair of lateral setae. Labrum ( Fig. 34 ) 2.5 times wider than long, anterior margin emarginated; with four long setae and two campaniform sensilla medially; two short setae and two campaniform sensilla close to emargination. Epipharynx ( Fig. 35 ) medially with two short setae and five pairs of rounded sensilla: three campaniform sensilla and two larger sensilla with four spots inside it; anterior margin with five robust setae on one lateral and four setae on the other lateral (this side probably lacking one seta) and eight short setae on median emargination. Mandibles ( Figs 36‒37 ) strongly sclerotized, with five distinct triangular teeth with serrated margin, except for the most proximal one, very small; dorsally with two long setae at the base and one medial sensillum, ventrally with tubercle medially. Maxillae and labium ( Fig. 33 ) connate. Maxillary palpi twosegmented, with a distinct palpiger. First palpomere with two setae and one campaniform sensillum ventrally, second palpomere conic and rounded at apex, with group of apical sensilla, one seta and one campaniform sensillum dorsally. Mala and lacinia not distinctly delimited from palpiger. Palpiger with two long setae and one campaniform sensillum ventrally. Lacinia on dorsal side of palpiger bearing spines at apex. Mala with nine stout, pointed setae. Paired stipes each with three long, pointed setae and one campaniform sensillum. Labial palpi onesegmented with group of apical sensilla and one campaniform sensillum laterally. Prementum with two long setae and two campaniform sensilla. Postmentum with three pairs of long setae.

Thorax. Pronotum with 24 pairs of setae and one pair of lateral prominent spiracles. Meso- and metanotum with setae shorter than those on pronotum: each side with two rows of 20 setae. Pro-, meso- and metasternum with numerous setae arranged in three groups: two on each lateral side and one medial. Thoracic sternites with setae distributed uniformly. Legs stout, three-segmented; coxa with numerous long setae, mostly at base. Femur with short and long setae distributed uniformly, with two very long setae and five campaniform sensilla at base. Tibiotarsus with single claw at apex, with numerous stout, pointed setae around claw.

Lateral scoli unbranched, with numerous spiniform projections bearing long, pointed setae at apex. Four pairs of scoli on prothorax, one pair on mesothorax, one pair on metathorax and one pair on abdominal segments I‒VIII. Scoli of pair II shortest, XII‒XIII longest, subequal to the supra-anal processes.

Abdomen with ten segments. Tergites I‒VIII with one pair of prominent lateral spiracles, their diameter slightly decreasing posteriorly, pair of tergite VIII extremely small. Abdominal tergites with chaetotaxy very similar to meso- and metanotum. Ventrites I‒III with most setae positioned medially, posterior ventrites with fewer setae, but uniformly distributed. Supra anal-processes unbranched, with smooth surface, many short setae at the base; thickened basally and tapering towards the apex.

Specimens examined. BRAZIL, Rio de Janeiro, Cachoeiras de Macacu, Reserva Ecológica de Guapiaçu, Yellow Trail (22°27'09,8" S, 42°46'13,8" W). First instar larvae: 3 collected on 30.vi.2013, Leocádio & Mermudes col. ( DZRJ501 ) (one dissected and one used on SEM), 4 collected on 23.ix.2013, Leocádio, M. col. ( DZRJ1104 ). Last instar larvae: 2 collected on 12.x.2013, Mermudes & Mattos col. ( DZRJ1105 ) (one dissected) .

Figures

FIGURES 1–3. Stolas aenea (Olivier, 1790) and host plant. (1) First instar larvae showing gregarious behavior; (2) adult; (3) host plant Mikania sp. 1.

FIGURES 4–11. Stolas aenea (Olivier, 1790), first instar larva. (4–5) Habitus, dorsal and ventral; (6) head; (7) maxillae and labium; (8) labrum; (9) epipharynx; (10–11) mandible, dorsal and ventral.

FIGURES 12–13. Stolas aenea (Olivier, 1790), first instar larva SEM images, habitus. (12) Dorsal; (13) ventral.

FIGURES 14–21. Stolas aenea (Olivier, 1790), first instar larva SEM images. (14) Head, ventral; (15) antenna; (16) clypeus and labrum; (17) labrum and mandible; (18) maxillae and labium; (19) right maxilla; (20) labium; (21) pronotum and mesonotum (with bifurcated seta in detail)

FIGURES 22–29. Stolas aenea (Olivier, 1790), first instar larva SEM images. (22) Pronotum; (23) meso-, metanotum and abdominal tergite I; (24) mesoleg; (25) abdominal lateral scoli; (26) abdominal tergites I–IV; (27) abdominal spiracle; (28) abdominal sternites; (29) supra-anal processes.

FIGURES 30–37. Stolas aenea (Olivier, 1790), last instar larva. (30–31) Habitus, dorsal and ventral; (32) head; (33) maxillae and labium; (34) labrum; (35) epipharynx; (36–37) mandible, dorsal and ventral.