Phaedon (Orthosticha) semimarginatus affinis (GUERIN)

Cabrera, Nora C., 2001, Description Of The Mature Larva Of Phaedon (Othosticha) Semimarginatus Affinis Guérin (Coleoptera: Chrysomelidae: Chrysomelinae), The Coleopterists Bulletin 55 (1), pp. 30-36 : 31-35

Description of Larvae of Phaedon (Orthosticha) semimarginatus affinis

( Figs. 1–10 )

Diagnosis. Phaedon (O.) s. affinis larvae are similar to those of P. concinus Stephens and P. cochleariae Fabricius in that tubercles Es and Ss are fused on the meso and metathorax and Dae are absent from abdominal segments 1– 6. They are different in having tubercles Dai and Dae separated on the meso and metathorax, tubercle Dai only present on abdominal segments 1–3 and in the absence of an additional frontal setae (f 2).

Mature Larvae. Habitus ( Fig. 1 ). Length: 4.8–5.3 mm; width: 1.76–1.90 mm (x: 10). Body weakly convex, dark brown: tubercles and inter­tubercular plates pale brown, distinct dorsally and ventrally; thorax and abdominal segments 1–7 with eversible glands.

Head ( Fig. 2 ). Width: 0.85–1 mm. Hypognathous, shape ovoid, shiny, dark brown. Epicranial suture distinct, well developed, extending about one fourth of head, frontal arms distinct throughout, divergent and gently curved. Endocarina present, extending to clypeus. Vertex with four setae (v1, v3, v4, v6): v1 and v4 simple, longest setae 1.50 length of antennae. Frons with four pairs of frontal setae (f1, f3, f4, f6) long, f2 absent and one pair of frontal sensillum (fsm). Antenna ( Fig. 8 ) short, 3­segmented; segment 1 short, weakly transverse or square; segment 2 longer than wide, segment 3 with conical sensory appendage at base. Stemmata ( Fig. 7 ) arranged in two groups, one pair of anterior stemmata posterior base of antennae, two pairs of posterior stemmata situated anterior base of antennae, four pairs of stemmatic setae (ss) present, ss 1 in posterior group of stemmata; ss2, ss3 and ss4 between anterior group of stemmata. Clypeus and labrum concolorous with head, clypeus with three pairs of setae, two pairs in medial area and one setae on lateral margins. Labrum ( Fig. 3 ) with medial notch acutely angulate, bearing four large median setae along anterior margin and two small setae laterally. Mandibles ( Fig. 4 ) brown, symmetrical, robust; 5­dentate, apical tooth sharply pointed; inner margin with fine serrations, bearing two large setae (ms) dorso laterally, basal setae slightly longer than lateral setae; dorsal surface with two mandibular sensilla (msm). Maxilla ( Fig. 5 ) cardo quadrangular; stipes as long as wide, with two large setae and one sensillum on external margin, near base of maxillary palp. Maxillary palp 4­segmented, segment 1 with one seta and one sensillum. Labium ( Fig. 5 ) with prementum and postmentum not fused together; postmentum with two pairs of postmental setae (pos 1–2), prementum with three pairs of premental setae (ps1–3). Labial palp 2­segmented, segment 1 with two large setae and one sensilum; segment 2 conical, nearly as long as wide, with 10 sensilla.

Thorax ( Fig. 10 ). Prothorax dark brown, dorsal side with tubercle D­DL­Epa large and tubercle Epp small. Tubercle D­DL­Epa with 10 large setae, four distributed anteriorly, two in lateral margin and other setae posteriorly; setal group 2 bisetose, with additional seta between setae 2 and 4; tubercle Epp with one seta. Pleural region with tubercle P (1S); sternal region with an oval tubercle Es­Ss (1S) fused across mid­ventral line. Dorsal surface of mesoand metathorax with four tubercles: tubercle Dai­Dae (2S) fused; tubercle Dpi (1S) oval, subequal to each other; tubercle DLpi (3S) round, smaller than Dpi, sometimes bisetose in the metathorax; tubercle DLae­DLpe (2S) round and convex. Epipleural region with two tubercles: tubercle Epa (2S) and Epp (1S) round, subequal to each one; pleural region with tubercle P (1S) oval, smaller than Epp. Sternal region with tubercle Es­Ss (2S) fused. Spiracles uniforous, situated separately on tubercle Epa of mesothorax. Eversible glands ( Fig. 9 ) on pro, meso and metathorax. Legs ( Fig. 6 ) similar in coloration, size and chaetotaxy; tarsal claw single, bearing single basal seta.

Abdomen ( Fig. 10 ) Segments 1–3 with three dorsal tubercles: tubercle Dai (1S) small, round, tubercle Dpi­Dpe (3S) transversely oval, tubercle DLae­DLpe (2S) round, convex. Epipleural region with tubercle Epa small, transversely oval; pleural region with tubercle P (2S) round. Sternal region with three primary tubercles: tubercle As­Ps (2S) round, subequal tubercle P, tubercle Ss (2S) transversely oval and tubercle Es (1S) round. A secondary tubercle as 1 with a micro seta on the antero­exterior part of tubercle Es. Segments 4–6 similar to segment 1 except for tubercle Dai absent; segments 7–9 with dorsal tubercle D­DL (4S) large; epipleural region with tubercle Epa small and pleural region with tubercle P (2S); sternal region with tubercle Es­Ss (3S) fused. Segments 1–8 with spiracles on tubercle Epa; segments 1–7 with eversible glands on tubercle DLpa­DLpe.

Natural History. Phaedon (O.) s. affinis has been recorded in association with Cordia L. ( Ehretiaceae ), Punica granatum L. ( Punicaceae ), Baccharis tandilensis Speg. (Compositae) and Solanum malacoxylon Sendt (Solanaceae) ( Bosq 1943; Rosillo 1944). Saini (1992) recorded specimens from Baccharis medullosa (Compositae) upon which P (O.) affinis may be a valuable biological weed control agent. Larvae and adults studied for this paper were collected on Salpichroa origanifolia (Lam) (Solanaceae) and Baccharis sp.

Larvae and adults of Phaedon feed in groups on upper and undersides of leaves. Females lay eggs on leaves in groups of 5 or 6 on undersides of leaves. There are three larval instars and pupation occurs in the soil at the base of the host plant.

Material Examined. ARGENTINA: 10 male, 20 female adults and 20 larvae, Buenos Aires, Gorina , X­XII­1991, Cabrera col. ( MLP) .

Figures

Figs. 1–6. Mature larvae of Phaedon (O.) semimarginatus affinis. 1) Habitus; 2) cephalic capsule, frontal view; 3) labrum; 4) left mandible, dorsal view; 5) labium and maxilla; 6) metathoracic leg. Scale: 1 mm.

Figs. 7–9. Mature larvae of Phaedon (O.) semimarginatus affinis. 7) cephalic capsule, lateral view; 8) antenna; lateral view; 9) eversible gland, lateral view.

Fig. 10. Body chaetotaxy of Phaedon (O.) semimarginatus affinis, right side. Pr: prothorax, Ms: mesothorax; Mt: metathorax, A 1–3: abdominal segment 1–3, A 4–6: abdominal segment 4–6, A 7–9: abdominal segment 7–9.