Heterogomphus dilaticollis

Moreno, Jhon César Neita & Orozco, Jesús, 2009, Larval and pupal descriptions for the genera Podischnus and Heterogomphus (Scarabaeidae: Dynastinae: Oryctini), Zootaxa 2168, pp. 34-44 : 40-43

Heterogomphus dilaticollis immature stages

The descriptions are based on 42 third-instar larvae and 8 pupae associated with two adults ( Fig. 4 ) with the following data: COLOMBIA: Cundinamarca: Bogotá, 4°35'56'' N, 76°04'51''W, 2599 m, in pasture ( Pennisetum clandestinum ), 22 November 2004. COLOMBIA: Cundinamarca: Mosquera, Finca Marengo Universidad Nacional de Colombia, 4°42'27'' N, 74°14'02'' W, 2546 m, 23 November 2002. COLOMBIA: Cundinamarca: Subachoque, Vereda Cánica Baja, Potosí Farm, 4°55'56'' N, 74°10'36''W, 2610 m, in pasture ( Pennisetum clandestinum ), 11/22/2004.

Description of third-instar larva. Dorsal body length 100–120 mm ( Fig. 5 a). Head. ( Fig. 5 b): Width of head capsule 9.8–12.0 mm. Cranium: densely punctate, dark reddish brown. Two dorsoepicranial setae, 10 epicranial setae in irregularly distributed groups, 8–9 paraocellar setae on each side. Ocelli present. Frontal suture and clypeofrontal suture distinct. Frons ( Fig. 1 ): 1 exterior frontal seta on each side; each anterior angle of frons with 2 setae. Clypeus: trapezoidal; surface of postclypeus reddish brown, well sclerotized, densely punctate; surface of preclypeus light brown with 1 lateral seta. Labrum: rugopunctate, slightly asymmetrical, suboval with 8 posterior setae, 4 lateral setae on each side, 2 anterior setae and 2 central setae. Antenna: with 4 antennomeres, antennomere 2 and 3 about 1/4 times longer than antennomere 1 and 4; antennomere 4 slightly longer than antennomere 1. Antennomere 4 oval in dorsal and ventral view, almond-shaped in lateral view; dorsal surface with 5–8 (more frequently 6) sensory spots ( Fig. 5 c); ventral surface with 8–11 (more frequently 8) sensory spots ( Fig. 5 d). Epipharynx ( Fig. 5 e): suboval, wider than long, left lateral edge angulate. Haptomeral process prominent and entire; right chaetoparia with 65 short, spine-like setae; left chaetoparia with 69 short, spine-like setae, with many sensilla; acroparia with 12 straight, long, thick setae; acanthoparia with 12–13 short, curved, spine-like setae; pedium large, ovate. Dexiotorma narrow and elongate; laeotorma slightly shorter than dexiotorma; epitorma curved to the right, pternotorma rounded. Dexiophoba absent; laephoba poorly developed between haptolachus and inner side of laeotorma, formed by 7 fine setae. Sclerotized plate of right nesium elongate and truncate at apex; sensory cone on left nesium represented by longitudinal, well-sclerotized plate, apex with 4 sensilla. Crepis poorly defined. Maxillae ( Fig. 5 f): Cardo subrectangular. Stipes longer than wide. Galea with abundant stout setae, 1 well-developed uncus at apex. Lacinia with abundant stout setae and 3 unci fused at their bases ( Fig. 5 g). Maxillary palpi with 4 palpomeres, all palpomeres of different lengths, palpomere 4 two times longer than palpomere 2. Stridulatory area with 10 blunt, truncate ridges ( Fig. 5 h) and with anterior truncate process. Hypopharynx ( Fig. 5 i): Glossa with 55 fine, long setae and 46 stout, short setae. Hypopharyngeal sclerome asymmetrical, medially concave, sharp process produced dorsally; left lateral lobe with 31 fine, moderately long setae; right lateral lobe with 40 fine, moderately long setae. Left margin with row of 16 stout, moderately long setae directed toward center of sclerome and 7 setae at base. Right mandible: Scissorial region with 4 teeth, basal tooth separated from S1-3; S1 and S2 fused, separated from S3 by scissorial notch; scrobe with 8 fine, long setae. Ventral surface with suboval stridulatory composed of 25 narrowly separated ridges; ventral process well developed, rounded, with many asperites ( Fig. 5 j). Dorsal surface with line of 12 fine, long setae. Brustia with 6 stout, long setae ( Fig. 5 k). Calx large, with 4 long, fine basolateral setae. Molar area with 3 wide, convex, ridged lobes (M1-3) and with 9 fine, long setae. Left mandible: ( Fig. 3 a–b): Scissorial region with 4 teeth, basal tooth separated from teeth S1-3; S1 and S2 fused, separated from S3 by scissorial notch. Scrobe with 6 fine, long setae. Dorsal surface with line of 20 fine, moderately long setae; acia well developed, sharp, setae at apex absent, 5 basolateral setae ( Fig. 5 l). Ventral surface with suboval stridulatory area composed of 28 narrowly separated ridges; ventral process well developed, rounded, with many asperites; dorsomolar area with row of 8 stout, fine, moderately long setae ( Fig. 5 m). Brustia with 6 stout, long setae arranged in form of a “u”. Molar area with 3 lobes, first molar lobe large.

Thorax. Prothorax irregularly and weakly sclerotized with 4 fine, long setae and transverse row of 13 long, fine setae; spine-like setae absent. Mesoprescutum with transverse with irregular row of 9 long, fine setae; mesoscutum with transverse row of 36 long, fine setae and 2 spine-like setae. Metaprescutum with 6 long, fine setae; spine-like setae absent; metaescutellum with 4 long, fine setae and 8 stout, spine-like setae. Prothoracic spiracles ( Fig. 5 n) 0.34 mm long, 0.56 mm wide; respiratory plate dark brown, bulla prominent; distance between respiratory lobes less than diameter of bulla; plate with 32 holes across diameter at middle, holes with irregular edges ( Fig. 5 o). Legs: tarsal claws with enlarged apical process, 1 basoexternal seta, 1 internal, preapical seta ( Fig. 5 p); prothoracic and metathoracic claws shorter than mesothoracic. Coxae, trochanter, and tibiotarsi of legs setose; setae fine or stout.

Abdomen. Abdominal spiracle I (0.34 mm long, 0.52 mm wide), shorter than spiracles II–VIII. Spiracles on segments II and VI equal in size (0.39 mm long, 0.55 mm wide), slightly larger than spiracles on segments VII and VII (0.41 mm long, 0.51 mm wide). Abdominal segment I on prescutum with 6 long, fine setae and 6 short, spine-like setae; subscutum with 9 long, fine setae; scutum with about 29 short, spine-like setae, 6 long, fine setae; scutellum with about 31 short, spine-like setae and 6 long, fine setae. Abdominal segment II on prescutum with 4 long, fine setae, 20 short, spine-like setae; subscutum with 9 long setae; scutum with 16 long, fine setae and 44 short, spine-like setae; scutellum with 4 long, fine setae and 51 short, spine-like setae. Abdominal segment III on prescutum with 4 long, fine setae and 39 short, spine-like setae; subscutum with 9 long, fine setae; scutum with 16 long, fine setae and 49 short, spine-like setae; scutellum with 6 long, fine setae and 49 short, spine-like setae. Abdominal segment IV on prescutum with 4 long, fine setae and 37 short, spine-like setae; subscutum with 9 long, fine setae; scutum with 16 long, fine setae and 53 short, spine-like setae; scutellum with 8 long, fine setae and 57 short, spine-like setae. Abdominal segment V on prescutum with 4 long, fine setae and 45 short, spine-like setae; subscutum with 9 long, fine seta; scutum with 16 long, fine setae and 51 short, spine-like setae; scutellum with 8 long, fine setae and 57 short, spine-like setae. Abdominal segment VI on prescutum with 6 long, fine setae and 40 short, spine-like setae; subscutum with 9 long, fine setae; scutum with about 8 long, fine setae and 53 short, spine-like setae; scutellum with ~40 long, fine setae and 40 short, spine-like setae. Abdominal segment VII with 2 rows of 12 fine, long setae and 39 short, spine-like setae mixed. Abdominal segment VIII with 2 rows of 9 fine, long setae. Abdominal segment IX with 47 fine, long setae distributed irregularly. Abdominal segment X with approximately 33 moderate to long, fine setae and 53 short, spine-like setae mixed. Pleural lobes with 15 long, fine setae. All spiracular areas with 13 long, fine setae and without short, spine-like setae. Raster: without palidia; campus with 6 fine, long setae; teges with 65–79 short setae that project toward superior anal lobe, barbula with 43 long, fine setae. Anal slit transverse.

Description of pupa. Male ( Fig. 6 ). Length 42.2 mm. Width at pronotum 20 mm. Body shape elongate, oval, stout. Color dark reddish orange. Entire body with fine, velvety-gold vestiture.

Head. Surface glabrous, bent sharply beneath thorax; antennae, labrum, mandibles, maxillae, and palpi discernible; antennal tecae expanded, stout, with apex rounded. Compound eyes sunken, scarcely visible. Frontoclypeus with strong, wide, massive horn projecting upwards in distal third.

Thorax. Pronotum: Surface glabrous. Wide, apex round; anteromedial tubercle, weakly defined. Mesonotum and metanotum well differentiated. Elytral and posterior wing tecae closely appressed, curved ventrally around body; elytral tecae extending to middle of abdominal segment II; posterior wing tecae extending to middle of abdominal segment IV. Protibia with 3 distinct teeth on external edge. Mesotibiae and metatibiae with inner and external well-developed spines.

Abdomen. Segments III–X well defined in ventral view. Segment VII slightly longer than preceding segment, segment VIII 1 /4 times longer than segment VII; segments VIII and IX fused. Segment X slightly prominent, small genital ampulla. Segments I–X with well-defined dioneiform organs in dorsal view, sclerotized between segments I–VI. Pleural lobes rounded. Spiracle I elongate, fine peritreme, covered by wing thecae; spiracles II–IV ovate, prominent, strongly sclerotized peritreme; spiracle V–VIII closed. Abdominal apex rounded, with fine, short setae.

Female. As male except in the following respects: Length 38.1 mm. Width at pronotum 19.6 mm. Head: Without tubercle. Abdomen: Segment X without genital ampulla.

Natural History. The life cycle of the species is one year. The pupal stage lasts from January to March. Adults have been taken primarily at lights at night. They had been observed flying between 18:30 to 05:00. The reproductive behavior of this species is similar to that found in other Oryctini ( Neita et al. 2006). The sexually mature male makes a gallery in the soil about 60 cm deep. Mating occurs outside the gallery, followed by the death of the male. The larvae feed on decomposing organic matter and have been observed feeding in crops, such as the roots of potato, corn, ornamental flowers, and different types of grasses (JCNM, personal observation).

Distribution. Heterogomphus dilaticollis occurs from Venezuela to Peru ( Endrödi 1976, 1985). This species is found in Colombia in forest areas from 1900–3500 m in the central and eastern cordilleras.

Figures

FIGURE 1. Podischnus agenor adults. a. male major; b. male minor; c. female.

FIGURE 3. Podischnus agenor pupa. a. ventral view; b. lateral view; c. dorsal view.

FIGURE 4. Heterogomphus dilaticollis adults. a. male major; b. male minor; c. female.

FIGURE 5. Heterogomphus dilaticollis third-instar larva. a. larva, lateral view; b. head; c. dorsal view of antennomere 4; d. ventral view of antennomere 4; e. epipharynx; f. maxilla; g. maxillar unci; h. maxillar stridulatory area; i. hypopharynx; j. right mandible, ventral view; k. right mandible, dorsal view; l. left mandible, dorsal view; m. left mandible, ventral view; n. respiratory plate; o. respiratory plate holes; p. tarsal claw.

FIGURE 6. Heterogomphus dilaticollis pupa. a. ventral view; b. lateral view; c. dorsal view.