Podischnus agenor (Olivier)

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 : 35-39

Podischnus agenor (Olivier)

This is the first species in the genus Podischnus to have its immature stages described. The descriptions are based on three third-instar larvae, two exuviae from third-instar larvae, and 2 pupae associated with adults ( Fig. 1 ) with the following data: COLOMBIA: Choco: Lloró, Granja Universidad Tecnológica del Chocó; 5º30.52'52''N; 76º44'33.33''W; 90 m; in rotten wood of Cedrela odorata L.; 18 November 1998.

Description of third-instar larva. Dorsal body length 85–101 mm ( Fig. 2 a). Head ( Figure 2 b). Cranium: Width 10–12 mm. Surface reddish brown, finely punctate; 4 dorsoepicranial setae, 25 epicranial setae distributed irregularly, 11–12 paraocellar setae on each side. Ocelli present. Frontal suture and clypeofrontal suture distinct. Frons: 1 exterior frontal seta, 1 posterior frontal seta on each side; 4–5 setae on each anterior angle. Clypeus: Form trapezoidal. Postclypeus reddish brown, well sclerotized, densely punctuate; preclypeus light brown, with 2 central setae and 2 lateral seta on each side. Labrum: rugopunctate, slightly asymmetrical, 8 posterior setae, 4 lateral setae on each side, 2 central setae. Antennae: 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 10–11 sensory spots ( Fig. 2 c); ventral surface with 9 sensory spots ( Fig. 2 d). Epipharynx ( Fig. 2 e): suboval, asymmetrical, left lateral edge angulate. Haptomeral process prominent, entire; right chaetoparia with 95 setae; left chaetoparia with 82 setae, with some sensilla; acroparia each with 21 straight, long, thick setae; corypha with 4 fine, long setae; acanthoparia with 12–13 short, curved, spine-like setae; pedium large, ovate. Dexiotorma elongate, narrow; laeotorma slightly shorter than dexiotorma. Dexiophoba absent; laephoba poorly developed between haptolachus and inner side of laeotorma, with 24 fine setae. Sclerotized plate of right nesium long, elongate, and truncate at apex; sense cone on left nesium represented by longitudinal, wellsclerotized plate, apex with 4 sensilla. Crepis poorly defined. Maxillae ( Fig. 2 f): cardo subrectangular. Stipes longer than wide. Galea with many stout setae and 1 well-developed uncus at apex. Lacinia with many stout setae and 3 unci fused at their bases ( Fig. 2 g). Maxillary palpi with 4 palpomeres, all palpomeres of different lengths, palpomere 4 twice as long as palpomere 2. Stridulatory area with 10 blunt, truncate ridges and an anterior truncate process ( Fig. 2 h). Hypopharynx ( Fig. 2 i): Glossa with 50 fine, long setae and 34 stout, short setae. Hypopharyngeal sclerome asymmetrical, concave medially, sharp process produced dorsally; left and right lateral lobes with 38 fine, moderately long setae. Left margin with row of 12 stout, moderately long setae directed toward center of sclerome and 3 basal setae at sclerome. Right mandible: apical tooth blade-like, S1 + S2 fused, S3 rounded after scissorial notch; scrobe with 16 fine, long setae. Ventral surface ( Fig. 2 j) with elongate-oval stridulatory area formed by 34 narrowly separated ridges; ventral process well developed, rounded, with many asperites. Dorsal surface ( Fig. 2 k) with line of 12 fine, long setae. Brustia with 6 long, stout setae. Calx large, with 11 basolateral setae. Molar area with 3 wide, convex, ridged lobes (M1-3) and with 9 long, fine setae. Left mandible: scissorial region with 4 teeth, basal tooth separated from S1-S3; S1 and S2 separated from S3 by scissorial notch. S3 and S4 notched. Scrobe with 14 long, fine setae. Dorsal surface ( Fig. 2 l) with line of 17 fine, moderately long setae; acia well developed, sharp, setae at apex absent, with 12 basolateral setae. Ventral surface with elongate-oval stridulatory area formed by 31 narrowly separated ridges ( Fig. 2 m); ventral process well developed, rounded, with many asperites; dorsomolar area with row of 12 stout, fine, moderately long setae; brustia with 14 stout, long setae arranged in form of a “U”. Molar area with 3 lobes, first molar lobe (M1) large.

Thorax. Pronotum irregularly and weakly sclerotized, with 8 long, fine setae. Prothoracic spiracles ( Fig. 2 n) 0.69 mm long, 0.49 mm wide; respiratory plate dark brown, bulla prominent; distance between respiratory lobes less than diameter of bulla; plate with 46 holes across diameter at middle, holes with irregular edges ( Fig. 2 o). Dorsum of prothorax with transverse row of 38 long, fine setae. Mesoprescutum with transverse, irregular row of 28 long, fine setae and 24 short, spine-like setae; metaprescutum with 32 long, fine setae; metascutellum with 22 long, fine setae and 40 short, fine setae; spine-like setae absent. Legs: Tarsal claws with enlarged apical process, 1 basoexternal seta and 1 internal, preapical seta ( Fig. 2 p). Tarsal claw on protarsi larger than claws on mesothoracic and metathoracic legs. Coxae, trochanter, and tibiotarsi of all legs setose, setae fine or stout.

Abdomen. Abdominal spiracle I 0.57 mm long, 0.38 mm wide, shorter than spiracles II–VIII. Spiracles on segments II and VI equal in size, 0.57 mm long, 0.42 mm wide; spiracles on segment VII slightly wider than preceding (0.57 mm long, 0.49 mm wide). Abdominal segment I with 21 long, fine setae on prescutum, 42 short, fine setae; subscutum with 18 long, fine setae; scutum with 8 long, fine setae, 18 short, fine setae, 13 short, spine-like setae; scutellum with 8 long, fine setae, 32 short, fine setae. Abdominal segment II on prescutum with 22 long, fine setae and 42 short, fine setae; subscutum with 18 short, fine setae; scutum with 8 long, fine setae, 18 short, fine setae, and 13 short, spine-like setae; scutellum with 8 long, fine setae, 32 short, fine setae. Abdominal segment III on prescutum with 18 long, fine setae, 62 short, fine setae, and 22 short, spine-like setae; subscutum with 51 short, fine setae; scutum with 10 long, fine setae, 102 short, fine setae and 46 short, spine-like setae; scutellum with 12 long, fine setae, 112 short, fine setae, and 89 short spine-like setae. Spiracular area with 61 long, fine setae. Abdominal segment IV on prescutum with 18 long, fine setae, 12 short, fine setae and 116 short, spine-like setae; subscutum with 58 long, fine setae and without short, spine-like setae; scutum with 18 long, fine setae, 165 short, fine setae and 126 short, spine-like; scutellum with 12 long, fine setae, 186 short, fine setae, and 168 short, spine-like setae. Spiracular area with 61 long, fine setae. Abdominal segment V with 18 long, fine setae, 196 short, fine setae, and 202 short, spine-like setae on prescutum; subscutum with 51 short, fine setae; scutum with 16 long, fine setae, 116 short, fine setae, and 226 short, spine-like setae; scutellum with 12 long, fine setae, 212 short, fine setae, and 109 short, spine-like setae. Spiracular area with 61 long, fine setae. Abdominal segment VI on prescutum with 22 long, fine setae, 122 short, fine setae, and 201 short, spine-like setae; subscutum with 56 short, fine seta and without short, spine-like setae; scutum with about 126 long, fine setae, 198 short, fine setae, and 198 short, spine-like setae; scutellum with about 10 long, fine setae, 118 short, fine setae, and 179 short, spine-like setae. Spiracular area with 61 long, fine setae. Abdominal segment VII with 2 rows of setae (anterior and posterior), each with 2 long, fine setae, 186 short, fine setae, and 28 short, spine-like mixed. Spiracular area with 61 long, fine setae. Abdominal segment VIII with 2 rows of setae, anterior row with 2 long, fine setae; posterior row with 4 long, fine setae, and 216 short, fine setae mixed. Spiracular area with 58 long, fine setae. Abdominal segment IX with one anterior row of 2 fine setae, and a posterior row with 4 long, fine setae mixed with 216 short, fine setae. Spiracular area with 58 long, fine setae. Abdominal segment X with approximately 124 moderate to long, fine setae and 391 short, spine-like, mixed setae. Spiracular area with 58 long, fine setae. Pleural lobes with 48 long, fine setae; short setae absent. Raster: without palidia; campus with 18 long, fine setae; teges with 125 short setae projecting toward superior anal lobe; barbula with 35–36 long, fine setae. Anal slit transverse.

Description of pupa. Male ( Fig. 3 ). Length 38.3 mm. Width at pronotum 18.6 mm. Body shape elongate, oval, stout. Color dark reddish orange. Entire body covered with fine, velvety-gold vestiture.

Head. Glabrous, bent sharply beneath thorax; antennae, labrum, mandibles, maxillae and palpi discernible; antennal tecae expanded, stout, with rounded apex. Compound eyes sunken, scarcely visible. Frontoclypeus with strong, wide, massive horn; apex broadly rounded.

Thorax. Pronotum: glabrous, anteromedial tubercle with rounded apex. Elytral and posterior wing tecae closely appressed, curved ventrally around body; elytral tecae extending to middle of abdominal segment IV; posterior wing tecae extending to middle of abdominal segment V. Protibia with 3 distinct teeth on external edge. Mesotibiae and metatibiae with inner and external spines well developed at apex.

Abdomen. Segments III–X well defined in ventral view. Segment VII slightly longer than preceding segment, VIII 0.25 times longer than segment VII; segments VIII and IX fused. Segment X with small and slightly prominent genital ampulla. Segments I–X with well-defined dioneiform organs in dorsal view, sclerotized between segments I–VII. Pleural lobes rounded. Spiracle I elongate, with fine peritreme and covered by wing thecae; spiracles II–IV ovate, prominent, with strongly sclerotized peritreme; spiracle V–VIII closed. Abdominal apex rounded, with fine and short setae.

Female. As male except in the following respects: Length 38.2 mm. Width at pronotum 15 mm. Head. Without tubercle. Abdomen. Segment X without genital ampulla.

Remarks. The following characters will separate the larvae of P. agenor from other Neotropical dynastine larvae: anterior frontal setae and posterior frontal setae present; laeophoba with 24 short, fine setae; stridulatory area with 10–11 blunt, truncate ridges; antennomere 4 with 10 dorsal sensory spots; spiracles on abdominal segments I–IV similar in size; spiracles on segments VII–VIII larger than those on preceding segments.

Natural History. Adults have been primarily collected at lights at night. They have been observed flying between 20:00 – 05:00. The adults had been taken between March, when the first rains start, through July. The males excavate a gallery in a stalk of Bambusa guadua H. & B. ( Poaceae ) or sugarcane ( Eberhard 1979). Mating occurs inside the stalk. Both beetles exit when mating is over. The larvae have been observed feeding in dead, rotten wood of Cedrela odorata L. ( Meliaceae ). The pupal stage lasts from January to March. The life cycle is of one year ( Neita et al. 2006).

Distribution. Podischnus agenor is distributed from México to Ecuador ( Endrödi 1976, 1985; Ratcliffe 2003). This species is found in Colombia in forest areas from the sea level to 1600 m.

Figures

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

FIGURE 2. Podischnus agenor 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 3. Podischnus agenor pupa. a. ventral view; b. lateral view; c. dorsal view.