Canthon bispinus Germar, 1824

González-Vainer, Patricia, 2019, Canthon bispinus Germar (Coleoptera: Scarabaeidae): Descriptions of the Third Instar and Pupa, The Coleopterists Bulletin 73 (1), pp. 233-238 : 234

Canthon bispinus Germar, 1824 third instar

( Figs. 1–15 )

Description. Body: C-shaped ( Fig. 1 ); length 18.0–20.0 mm; maximum pronotal width 1.9–2.0 mm; maximum abdominal width 5.0 mm; color white.

2) Head, frontal view.

Cranium: Maximum width of head capsule 1.9–2.0 mm ( Fig. 2 ). Surface of cranium finely punctate, light yellow-brown. Surface area of clypeus, labrum, and mandibles light yellow-brown. Epicranial suture distinct; frontal suture extending almost to base of antenna.Each side of epicranium with 2 dorsal setae and 5 lateral setae; 2 lateral setae grouped next to base of antenna. Frons on each side with 2 exterior frontal setae and 1 seta in each anterior angle. Fronto-clypeal suture rectilinear. Labrum: Symmetrical, trilobed, width 2X length, with 4 long setae on apex of medium lobe ( Fig. 3 ). Lateral lobes with 5 setae on anterior margin that are progressively longer toward external angle and 2 long lateral setae. Disc with 2 rows of setae: distal row arcuate with 8 setae, 2 middle setae shorter and thicker; basal row with 6 setae, 2 central setae shorter. Epipharynx: Typically trilobed, with rounded lateral margin ( Fig. 4 ). Corypha with coarse setae; 5 marginal setae long and moderately long; proximal area of corypha with 5 spine-like setae and 2 moderately long setae on each side. Left and right acroparia with 4 long marginal setae and 2 moderately long proximal setae. Each acanthoparia with 2–3 setae. Pedium bearing 14 scattered, spine-like setae. Each chaetoparia consisting of about 4–6 stout setae. Dexiotorma and laeotorma elongated, united, with rhomboidal fused epitorma. Tormae symmetrical. Mesophoba monostichous Antennae: Foursegmented, 3 rd antennomere with conical sensory organ; last antennomere markedly small ( Fig. 5 ). Mandibles: Thick, asymmetrical. Right mandible with broad base and 2 rounded, unequal scissorial teeth separated by a marked groove; distal tooth bilobed ( Figs. 6–8 ); molar area strongly lobed, with 2 blunt teeth in dorsal view ( Fig. 8 ); external area with 2 setae; ventral surface with well-marked stridulatory area with a row of short, spine-like setae ( Fig. 6 ). Left mandible with 3-toothed scissorial area ( Figs. 9–11 ); mola concave ( Fig. 10 ) with distal, tooth-like protrusion in dorsal view ( Fig. 9 ) and with blunt distal tooth in ventral view ( Fig. 11 ); lateral area with 2 long setae; ventral stridulatory area with 5 short, spine-like setae, larger than those of right mandible ( Fig. 11 ). Maxilla: Dorsal surface of stipes with 6 long setae at the middle area ( Fig. 12 ), and stridulatory area with an uneven row of 8 short, conical, anteriorly pointing teeth. Uncus of lacinia acute, without a proximal tooth; dorsal surface of lacinia with strong, long setae: 2 setae close to base of uncus, 6 setae grouped in middle area, and a row of 6 lateral setae. Galea covered by long, strong setae, with a small conical uncus. Labiumhypopharynx: Central lobe of glossa with 7 thick, pointed setae arranged in 3 longitudinal rows on each side, and 1 long seta on the middle of anterior margin ( Fig. 13 ). Lateral lobes of glossa setose. Hypopharyngeal area bounded on each side by mesally directed fringe of fine, stout, short setae. Oncyli asymmetrical, strongly sclerotized. Thorax: Prothoracic shield with anterior, angular projection en each side. Legs 2- segmented; apex of each leg with a circle of 8 short, spine-like setae and 2 terminal setae ( Fig. 14 ). Prothoracic spiracle reniform, with concave margin directed postero-ventrally; 0.15 mm long, 0.09 mm wide; respiratory plate light brown, with circular holes. Abdomen: Segments I–VII with 2 rows (anterior and posterior) of short setae; segments VIII–IX with 1 posterior row of short setae. Raster with patch of 10 very small, short, spine-like teges on each side, and 4 pairs of teges on medial region, arranged symmetrically; palidia absent ( Fig. 15 ).

Figures

Figs. 1–2. Canthon bispinus, third instar. 1) Habitus;

Figs. 3–11. Canthon bispinus, third instar. 3) Labrum; 4) Epipharynx; 5) Antenna; 6) Right mandible, ventral view; 7) Right mandible, frontal view; 8) Right mandible, dorsal view; 9) Left mandible, dorsal view; 10) Left mandible, frontal view; 11) Left mandible, ventral view. Scale bars = 0.25 mm.

Figs. 12–17. Canthon bispinus. Third instar: 12) Left maxilla, dorsal view; 13) Hypopharynx, dorsal view; 14) Prothoracic leg; 15) Raster. Pupa: 16) Dorsal view; 17) Lateral view.