Hybosa acutangula, Spaeth, 1913, Spaeth, 1913

Begha, Bruno Piotrovski & Oliveira, Sarah Siqueira, 2024, Description of larva, pupa, and genitalia of Hybosa acutangula Spaeth, 1913 (Coleoptera: Chrysomelidae: Cassidinae) from the Brazilian Cerrado, Revista Brasileira de Entomologia (e 20230048) 68 (1), pp. 1-7 : 2-5

Results

Description of fifth larval instar ( Figs. 2-4 )

Body length: 10.56 mm (Average for two specimens). Body 2.5 times longer than wider, long, and flattened. Body of early instars wholly brown, older instars and pre-pupa wholly green; sclerotized portions of the body, cranium, legs and scoli, dark brown to black.

Scoli spike-like and slightly curved with small thin setae, varying from two to four setae on each side of the scolus, and one at the tip. Mesonotum, metanotum and abdominal segments I-VII with two rows of small setae disposed horizontally, and groups of small setae present at the base of each scoli, in dorsal view. All thoracic segments with groups of small setae at their outer edges and the median portion, abdominal segments with irregularly distributed setae in ventral view.

Head sclerotized, rounded in frontal view, slightly flattened in lateral view; with six stemmata on each side, four grouped dorsolaterally and two grouped laterally to the antenna. Chaetotaxy of the head symmetrical. On each side of head, frons bearing 12 frontal setae, three small setae near the epicranial suture, three setae near the insertion of the antenna, epicranium bearing three setae. Labrum, posterior margins rounded with slight recess at the median portion, bearing four setae distributed horizontally; with one large and one small seta in the frontal region of the dorsolateral stemmata, one large seta in between the dorsolateral stemmata, two large visible setae behind the stemmata. Antennae two-segmented. Basal segment short and round lacking setae; distal segment cylindrical, with a smaller diameter than the previous segment, bearing two small setae at the apex. Mandibles sclerotized, right mandible with five teeth, left mandible with four teeth; all teeth crenulated. Maxillae and labium connate. Maxillary palps two segmented, each segment bearing two setae at the laterals. Palpiger well-developed, mala conical, with setae at the inner face.Labial palp conical, one segmented. Ligula rounded, divided in the middle. Prementum with two setae. Postmentum with four setae.

Thorax wider than the abdomen. Pronotum wide, with two grooved areas in the median portion, with four scoli on each side; three scoli at most frontal region forming a group with a shared black integument insertion, one pointing onwards and two smaller pointing diagonally;one large scolus pointing laterally.Mesonotum and metanotum similar, with two scoli on each side, the anterior scolus smaller than the posterior; each segment also with two rows of small setae dorsally.Mesonotum with one spiracle at the anterior portion, dorsolaterally positioned. All legs similar. Coxa, femur and sclerotized, notably darker on the darker face of the tibia and distal femur;coxa stout and short,femur and tibia subequal in cylindrical, tibia slightly shorter than femur; all segments with irregularly distributed setae, setae of the inner face of femur longer than of the outer face, setae of the outer face of tibia longer than of the inner face, apex of tibia with higher density setae. Tarsungulus sclerotized and hook-like.

Abdominal segments very wide and short, second segment slightly over four times longer than wide; the others similar, gradually narrowing. Segments I-VIII with one lateral scolus on each side; segments I-VII bearing one spiracle on the dorsal portion of each segment near the base of the scolus, gradually decreasing in diameter; anal fork of segment VIII with parallel sides and the apical portion slightly inflated, the anal fork is maintained during all the immature instars; segments VIII and X forming the anal tube.

Description of pupa ( Fig. 5 )

Body length: 9.43 mm (Average for two specimens). Body 1.6 times longer than wide (excluding the scoli), convex shape. Body green and glabrous.

Head 1.4 times longer than wide, with two short, rounded processes at apex; antennae divergent, a portion of the antenna hidden behind anterior leg, apex of the antenna reaching the apex of the femur. Mouthparts visible.

Pronotum wide, over two times wider than long, with a small recess at the front, anterior margin with three short rounded processes bearing very fine small setae on each side; posterior laterals of the pronotum with a rounded process pointing backward; posterior median margin with rounded projection over metanotum. Mesonotum transverse, scutellum noticeable, lateral projections rounded.Metanotum transverse with anterior margin bisinuated, posterior margin transverse, very slightly projected medially. Elytra and wings visible only in ventral view. All legs similar, anterior and middle legs visible, posterior legs covered by the elytra, except the tarsi.

Abdominal segments very wide and short, first segment slightly over 6.5 times wider than long; the others similar, gradually narrowing. Segments I and II with anterior margins slightly bisinuated; segments I-V with one very visible lateral scolus on each side with small setae, reducing in size gradually, scoli in segments I-III larger and curved, scoli on segments IV-V smaller and spike-like, and segment VI with a minute spike-like process; segments I-V bearing one spiracle positioned dorsolaterally of each side, spiracle in segment I larger, spiracles in segment II-IV similar, spiracle in segment V slightly smaller than the previous spiracle; segments I-IV covered by elytra in ventral view.Anal fork reduced, but visible.

Description of female genitalia ( Figs. 6a and 6b )

Spermatheca well-sclerotized, vasculum large and curved, with narrow base and rounded distal portion, distal curved portion nearly two times the length of the proximal straight, hook-like; ductus spiral and long. Tignum with base 2.5 times broader than the apex, containing various setae. Laterals slightly less sclerotized. Median section slightly constricted. Apex of the tignum straight, with vertexes slightly pointing forward.

Description of male genitalia ( Figs. 6c and 6e )

Median lobe curved, not falciform, tip slightly tapered in lateral view. Tegmen attached to the base of the median lobe, cruciform in ventral view, anterior section rounded, lateral “wing-like” and slightly curved backward, basal section thin.

Material studied

Adult beetles: BRAZIL: Goiás: Goiânia, Bosque August Saint-Hilaire , Manual collection – fence, Begha, B.P., 20.X.2022, 1 dissected male; 31.X.2022, 1 dissected male; 31.X.2022, 2 dissected females ( MZUSP); 31.X.2022, three undissected specimens ( ZUFG).

Immatures: BRAZIL: Goiás: Goiânia, Bosque August Saint-Hilaire , Manual collection – fence, Begha, B.P., 20.X.2022, 3 larvae; 20.X.2022, larva with dissected mouthparts; 20.X.2022, pupa; 03.XI.2022 parasitized pupa ( MZUSP).

Parasitoid wasps: BRAZIL: Goiás: Goiânia, Bosque August Saint-Hilaire , reared in laboratory, Begha, B.P., 03.XI.2022, Brachymeria wasp; 06.XII.2022, Conura wasp ( MZSUP) .

Figures

Figure 2 Hybosa acutangula Boheman,1855.Fifth instar larvae:a, dorsal view;b, ventral view.AFK,anal fork;ASP,abdominal spiracles;ATB,analtube;SCL,scolus;TSP,thoracic spiracle. Scale bar = 1 mm.

Figure 3 Hybosa acutangula Boheman, 1855.Fifth instar larvae,frontal view of the head. ANT,antenna; ECS,epicranial suture; LBR,labrum; STM,stemma.Scale bar = 1 mm.

Figure 4 Hybosa acutangula Boheman, 1855.Fifth instar larvae, mouthparts:a, left mandible, ventral view;b, right mandible,ventral view;c, labium, ventral view.LBM,labium; LBP, labial palpus; LGL, ligula; MAL, mala; MDT, mandibular teeth; MXP, maxillary palpus; PPG, palpiger. PRM, prementum; PSM, postmentum. Scale bar = 1 mm.

Figure 5 Hybosa acutangula Boheman, 1855. Pupa: a, dorsal view; b, ventral view. Scale bar = 1 mm.

Figure 6 Hybosa acutangula Boheman, 1855. Genitalia: a, female, tignum, dorsal view; b, female, spermatheca, lateral view; c, male, aedeagus, ventral view; d, male, aedeagus, lateral view; e, male, aedeagus, dorsal view.DCT,ductus; MDL, medianl lobe; TGM, tegmen; VSC, vasculum.Scale bar = 500Μm.