Mesomphalia gibbosa ( Fabricius, 1781 )

Simões, Marianna V. P. & Monné, Marcela L., 2014, Description of immatures of Mesomphalia gibbosa (Fabricius, 1781) and Mesomphalia turrita (Illiger, 1801) (Coleoptera: Chrysomelidae: Cassidinae: Mesomphaliini), Zootaxa 3861 (5), pp. 466-478 : 467-470

Mesomphalia gibbosa ( Fabricius, 1781)

( Figs. 1–7 )

Biology. Mature larvae had fecal material and cast exuviae of previous instars piled on the supra-anal processes. The pupa was attached by its sternum to the leaf surface.

Last-instar larva ( Figs. 1, 3–7 ). Measurements (n = 1). Length, excluding head, from anterior border of pronotum to base of supra-anal processes: 8.9; width of mesonotum, excluding lateral scoli: 5.6.

Body ( Fig. 1 ) flattened dorso-ventrally, oval, in life widest across metathorax, but artificially widest across abdominal segments due to fixation ( Fig. 1 ), slightly narrowed posteriorly. Fourteen pairs of lateral scoli and a pair of supra-anal processes. Scoli of pairs IV shortest, XIII longest, about 1.5 times longer than supra-anal processes. Lateral scoli unbranched, covered with setae, armed with an acute seta at apex. Supra-anal processes short, with smooth surface, sinuate, slightly thickened basally, tapering to apices, similar in length to lateral scoli VII–XI, slightly bent dorsally.

Color: Integument of ethanol-preserved larva orange-yellow, with lateral scoli and apex of supra-anal process brown. Head yellowish brown. Basal half of clypeus brown. Pronotum with two brown spots anteriorly and two posteriorly along body axis; mesonotum with 12 spots, six anteriorly and six posteriorly; metanotum with ten spots, five anteriorly and five posteriorly; thoracic sternites yellow, brownish-yellow laterally; abdominal tergites with ten longitudinal brown spots in two rows on I–VI: four spots in anterior row and six in posterior row; tergite VII with four brown spots: two spots in anterior row and two in posterior; abdominal sternites I–IV brown with yellow stripes along body axis, V–VII brown with two longitudinal yellow stripes medially, and VIII with two longitudinal brown stripes medially. Legs brown. Setae: Dorsal and ventral surfaces with distinct microtrichia, short setae concentrated at posterior angle of pronotum and on lateral border of abdominal segments.

Head ( Fig. 3 ) well sclerotized, hypognathous, retracted into prothorax; frons with numerous regularly distributed setae; vertex laterally with only four minute setae, tempora with four long setae. Endocarina complete, connected to fronto-clypeal suture. Antennae two-segmented, set in membranous ring; first segment transverse, twice as wide as second segment, with two campaniform sensilla laterally; second segment stout, around 1.5x longer than wide, with group of peg-like sensilla apically, one of them prominent. Six paired prominent stemmata laterally. Fronto-clypeal suture present. Clypeus distinct, wider than long, with pair of lateral setae. Labrum ( Fig. 4 ) wider than long, anterior margin emarginated, with two short setae medially and eight long setae laterally; dorsally ( Fig. 4 a) with four setae, two pairs of campaniform sensilla and five short longitudinal sulci on left and four on right side; ventrally ( Fig. 4 b) with emargination adorned with six short setae ( Fig. 4 b), surface adorned with two small setae medially, three campaniform sensilla and two groups of small sensilla laterally. Mandibles ( Fig. 5 ) heavily sclerotized, palmate, with four distinct, triangular apical teeth (upper to lower margin): first and second teeth apically acute, third slightly blunt, fourth abruptly truncate internally. Dorsally ( Fig. 5 a) of mandibles with two setae and three basal campaniform sensilla. Maxillae and labium ( Fig. 7 ) connate. Paired stipes each with three long, pointed setae apically and two campaniform sensilla medially. Mala and lacinia not distinctly delimited from palpiger. Palpiger with five long acute setae, one short seta, and three campaniform sensilla. Lacinia ( Fig. 6 ) covered with spines on dorsal side of palpiger. Mala bearing eight long pointed lateral setae, and two short blunt apical setae. Maxillary palpus two-segmented: first segment with three setae medially and one campaniform sensillum laterally ( Figs. 6–7 ), second segment with group of apical sensilla. Labial palpi one-segmented with group of apical sensilla and one campaniform sensillum laterally. Prementum trapezoidal with six long and two short basal setae, and four campaniform sensilla. Postmentum with two short setae medially and six long setae laterally.

Pronotum with numerous setae, most concentrated at posterior margin. Meso-, metanotum and abdominal tergites with setae distributed uniformly on their surfaces. Pro-, meso- and metasternum with numerous setae arranged in three groups, one on each side and one central. Thoracic sternites with setae distributed uniformly. Legs stout, three-segmented, all segments covered with numerous long setae; setae of legs shorter than setae of body surface, except for two long setae placed on femur ventrally, shorter than body length. Femur with short setae distributed regularly, with two very long setae and group of eight campaniform sensilla on ventral side. Tibiotarsus heavily sclerotized, apically with single, simple claw. Claw with two long setae apically and one pointed seta at base, surrounded by numerous long blunt setae.

Spiracles of thorax and abdominal segments I–VII distinctly elevated and their diameter very slightly decreasing posterad. Segment VIII extremely reduced. Tergite VIII distinct, simple, not sclerotized, with short sparse setation arranged in a central transverse row. Tergite IX lacking spines or setation, with paired supra-anal processes ( Fig. 1 ); supra-anal processes short, with smooth surface, sinuate, slightly bulging basally, tapering to apices, measuring the same in length as lateral scoli VII–XI, slightly bent dorsally.

Remarks. We could not observe the lateral campaniform sensillum on the clypeus or one lateral seta of the second maxillary palpomere. Only six short setae were observed on the anterior margin of the labrum, while M. turrita and other immatures previously described in the tribe bear eight setae at this location ( Świętojańska 2009).

Pupal exuvia ( Fig. 2 ). Measurements (n = 1). Length of body: 14.0; width across second abdominal segment, without lateral scoli: 7.0. Length of pronotum: 5.0; width of pronotum 10.5.

Body oval. Integument of ethanol-preserved pupa yellow. Pronotum yellow with anterior margin, posterior margin, and median longitudinal stripe, brown. Meso- and metanotum yellow with median longitudinal stripe brown. First abdominal tergite yellow with anterior 2/3 brown. Abdominal tergites II–IX with lateral and median longitudinal stripe brown; body axis from tergites II–V brown. Lateral scoli smooth, I–V brown, and VI–VII whitish yellow. Elytral portions brownish yellow.

Abdominal segments I–II with distinct leaf-like lateral scoli; IV–VII with scoli truncate at base and conical at top; I pointing upward; II–V outward; VI–VII folded laterally, pointing downward. Size of scoli decreasing posterad.

Tergites covered with short setae. Abdominal tergites I–VI with pair of spiracles; diameter of each pair of spiracles decreasing posterad.

Exuvia of last instar remain attached caudally to the pupa.

Figures

FIGURES 1 – 7. Mesomphalia gibbosa (Fabricius, 1781). Last-instar larva and exuvia. 1, general aspect of last-instar larva; 2, exuvia; 3 – 7, last-instar larva: 3, head; 4 – 7, mouth parts: 4 a – b, labrum: 4 a, dorsal view; 4 b, ventral view; 5, mandibles: 5 a, dorsal view; 5 b, lateral view; 6, dorsum of palpiger and maxillary palp; 7, maxillae and labium ventrally; (lac, lacinia; lp, labial palp; mal, mala; mpI, maxillary palp I; mpII, maxillary palp II; post, postmentum; pp, palpiger; pre, prementum; st, stipes).