Steirastoma stellio Pascoe, 1866

Casari, Sônia A., 2016, Morphology of Immatures of Acanthoderini (Cerambycidae, Lamiinae), Zootaxa 4139 (1) : -

Steirastoma stellio Pascoe, 1866

( Figs. 47‒57 , 74 )

Redescription of larva (based on last larval exuvia). Coloration: head yellowish with anterior dark-brown band dorsal and brown ventral, forming mouth frame; black mandibles; membranous maxillae and labium with light brown bands. Pronotum yellowish, irregularly granulate on median third. Integument densely covered by microsetae; setae long and ferrugineous denser on prothorax and laterally. Ampullae with spiculate moniliform tubercles. Spiracles broadly elliptical.

Head ( Fig. 47 ) with numerous microsetae on anterior region; prognathous, moderately flattened; head capsule entire dorsally, with lateral margins almost straight. Median suture and endocarina present; frontal suture distinct only behind antennal foramina. Epistomal margin slightly emarginate at middle, strongly sclerotized, with three pairs of moderately long setae near anterior margin: one pair at middle and one pair each side. Each epicranial half dorsally with five setae dorsal and six ventral. One stemma each side, below antenna. Gular sutures long, with five setae each side. Antennae ( Fig. 48 ) retractile, short, with three antennomeres; median, elongate, bearing at apex, one long, lateroventral, cupuliform sensorial appendix and distal antennomere dorsal; sensorium longer than distal antennomere; distal antennomere reduced, bearing dorsally one campaniform sensillum near base, and apically, two long and two short setae and one membranous sensorial ventral appendix. Clypeus membranous, glabrous and trapezoidal, 2.9X wider than long. Labrum ( Fig. 49 ) transverse, 2X wider than long, with margins strongly rounded, bearing numerous long and wide setae more concentrated on anterior half. Epipharynx ( Fig. 50 ) rounded, membranous with one sclerite each side on basal half; long and wide, innerly directed setae on anterior half and between sclerites. Mandibles ( Figs. 55‒57 ) symmetrical, wide at mesal region; cutting edge wide, oblique and grooved innerly, with one small dorsal lobe near apex; mesal area with transverse grooves; outer face with transverse impression on distal third, one longitudinal weak short furrow apicad and two seta near base. Maxillae ( Figs. 52, 53 ) ventrally: stipes with transverse, inclined, brown band near middle and long setae near/on dark band; cardines and maxillary articulating areas fused to submentum; mala elongate with rounded apex and numerous wide and long setae dorsal and ventral. Palpifer membranous anterior and laterally, with numerous setae. Maxillary palpi with three elongate palpomeres: basal, bearing four lateroexternal moderately long setae ventral and three very long dorsal setae near apex; median, bearing five ventral and two laterodorsal setae; distal, narrower, bearing one lateroexternal short seta and many peg-like sensilla at apex. Labium ( Fig. 53 ) ventral: postmentum membranous bearing each side, two long setae anterior and three (one short) near base; prementum wider and membranous on anterior half; numerous long setae on membranous area; one laterobasal short seta and five setal pores on each side; ligula slightly shorter than labial palpus with anterior margin rounded and many wide and moderately long setae near middle. Palpiger membranous with numerous setae of varied sizes. Labial palpi with two elongate palpomeres: basal, bearing several anterior wide and long setae dorsal and ventral and about five setal pores; distal, bearing ventrally one campaniform sensillum and numerous peg-like sensilla at apex. Hypopharynx ( Fig. 51 ) membranous, bulging with a sclerotized longitudinal band each side and numerous long setae, inwardly directed, near lateral margins.

Abdomen: dorsal and ventral ampullae with one transverse furrow and numerous spiculate tubercles each side.

Material examined. BRAZIL. São Paulo: Peruíbe, 24‒25.VI.1980, Exp. MZUSP col., 1 larva reared to adult (last larval and pupal exuviae) ( MZSP 8550), 1 pupa reared to adult ( MZSP 8542).

Remarks. Based on studied species ( S. stellio ) and descriptions of S. breve , S. marmorata and S. meridionale , the larvae of Steirastoma are defined as having head moderately depressed with sides strongly rounded and slight convergent posteriorly, microsetose or not anteriorly; mouthframe strongly sclerotized, dark-brown; 1‒5 pairs of setae each side of gular suture; antennae with three antennomeres; supplementary hyaline process longer than distal antennomere; dorsal ampullae of abdomen with transverse furrows and micro-spiculate tubercles, except S. marmorata and S. meridionale , glabrous.

The pupa of Steirastoma is unknown.

Figures

FIGURES 47 ‒ 57. Steirastoma stellio Pascoe, 1866. Larva: 47, head (ventral); 48, apex of antenna (ventral); 49, frons, clypeus and nasal; 50, epipharynx; 51, hypopharynx; 52, maxilla (dorsal); 53, maxilla and labium; 54, spiracle (thoracic); 55 ‒ 57, mandible (internal, ventral, dorsal). Bars = 0.5 mm, except fig. 47 = 0.1 mm; figs. 55 ‒ 57 = 1 mm.

FIGURES 70 ‒ 80. Habitus. Psapharochrus jaspideus (Germar, 1824): 70 ‒ 72, larva (dorsal, lateral, ventral); 73, adult (dorsal). Steirastoma stellio Pascoe, 1866: 74, adult (dorsal). Psapharochrus vetustus (Bates, 1880): 75 ‒ 77, larva (dorsal, lateral, ventral); 78, adult (dorsal); 79 ‒ 80, pupa (dorsal, ventral).