Homophileurus tricuspis Prell

Moreno, Jhon César Neita & Ratcliffe, Brett C., 2011, Immature stages of Homophileurus tricuspis Prell (Coleoptera: Scarabaeidae: Dynastinae: Phileurini) with notes on natural history and distribution in Colombia, Zootaxa 2915, pp. 20-28 : 21-27

Homophileurus tricuspis Prell

Figs. 1 –12

Specimens examined. Eight third instars and six pupae with the following data: “ Colombia, Chocó, Unguía, Potrero. Rivera del Río Tigre. En: Nido de Nasitutermes (sic) sp. ( Isoptera : Termitidae : Nasutitermitinae). 8°04´54.26´´N; 77°02´54.26´´W. 10 m alt. 18 Nov. 2009. J. C. Neita Leg.”. Larval voucher specimens are deposited in the collections of Jhon Neita and the University of Nebraska State Museum; adult voucher specimens are deposited in the Neita collection.

Third Instar. Cranium ( Fig. 1): Width of head capsule 6.63–6.84 mm. Color reddish brown. Surface strongly punctate on middle third. Frontal suture and clypeofrontal suture distinct. Frons ( Fig. 1): Surface with 1 exterior frontal seta and 2 posterior frontal setae on each side; each anterior angle with 2 setae; remaining cranial surface with 3 dorsoepicranial setae, 14 epicranial setae distributed irregularly, and 6–8 paraocellar setae on each side. Anterior frontal setae absent. Ocellus present. Clypeus: Form trapezoidal. Surface of postclypeus reddish brown, well sclerotized, densely punctate; surface of preclypeus light brown, with 2 central setae and 3 lateral setae on each side. Labrum: Surface rugopunctate, slightly asymmetrical, with 6 posterior setae, 5 lateral setae on each side and 2 central setae. Epipharynx ( Fig. 2 ): Form suboval, asymmetrical, left lateral margin angulate. Haptomeral process prominent, entire. Right chaetoparia with 75 setae; left chaetoparia with 82 setae, with some sensillae between setae. Acroparia with 16 straight, long, thick setae; corypha with 6 slender, long setae; right acanthoparia with 8 short, curved, spine-like setae; left acanthoparia with 10 short, curved, spine-like setae. Pedium longer than wide, without setae. Dexiotorma narrow, elongate; laeotorma slightly longer than dexiotorma; epitorma curved onto disc of pedium, pternotorma rounded. Dexiophoba absent; laephoba poorly developed; haptolochus and inner side of laeotorma with 12 small, slender setae. Sclerotized plate of right nesium elongate, acute at apex; sense cone on left nesium represented by longitudinal, well-sclerotized plate, apex with 3 sensillae. Crepis poorly defined. Right mandible ( Figs. 3a–b): Scissorial area with blade-like, apical tooth (S1 + S2 fused) and 1 small, rounded tooth (S3) behind scissorial notch. Scrobe with 12 slender, long setae. Dorsal surface with line of 13 slender, long setae. Ventral surface with elongate-oval stridulatory area formed by 47 narrowly separated ridges. Ventral process well developed, rounded, with many asperites. Brustia with 20 stout, long setae. Calx large, with 5 basolateral setae. Molar area with 3 wide, convex, ridged lobes (M1-3). Ventral surface with 16 slender, long setae. Left mandible (Figs. 4a–b): Form falcate. Scissorial region with 4 teeth, basal tooth separated from teeth S1-S3; S1 and S2 separated from S3 by scissorial notch. Scrobe with 12 slender, long setae. Dorsal surface with line of 10 slender, moderately long setae; acia well developed, sharp, with 6 basolateral setae; dorsomolar area with row of 12 stout, slender, moderately long setae. Ventral surface with elongate-oval stridulatory area formed by 43 narrowly separated ridges; ventral process well developed, rounded, with many asperites. Brustia with 18 stout, long setae arranged in form of a “U”. Molar area with 3 lobes, first molar lobe (M1) large. Maxilla ( Figs 5a–b): Cardo subrectangular. Galea with 6 stout setae and 1 well-developed uncus at apex. Lacinia with many stout setae and 3 unci fused at their bases, 1st and 2nd unci separated from 3rd, 3rd shorter than 2nd. Maxillary palpus with 4 palpomeres, palpomere 4 twice as long as palpomere 2. Stridulatory area ( Fig. 6) with 7 blunt, truncate ridges, anterior process truncate. Hypopharynx ( Fig. 7 ): Glossa with 31 slender, long setae and 36 stout, short setae. Hypopharyngeal sclerome asymmetrical, concave medially, with acute dorsal process. Left lateral lobe with 20 slender, moderately long setae; right lateral lobe with 14 slender, moderately long setae. Left margin with row of 28 stout, moderately long setae directed toward center of sclerome and without setae near base of sclerome. Antenna: With 4 antennomeres, antennomeres 1–2 subequal in length, each slightly longer than antennomere 3; terminal antennomere about half length of antennomere 2. Apical antennomere with 5 sensory spots on dorsal surface (Fig. 8), ventral surface with 8–10 sensory spots (Fig. 9). Thorax: Pronotum wide, irregularly and weakly sclerotized, with 6 slender, long setae. Prothoracic spiracle (Fig. 10a) 0.207 mm long, 0.316 mm wide; respiratory plate dark brown, regularly shaped as a closed “C”, spiracular bulla rounded, slightly prominent; distance between respiratory lobes less than diameter of bulla; plate with 38–48 holes across diameter at middle, holes with regular edges (Fig. 10b). Dorsum of prothorax with transverse row of 4 long, slender setae and 28 spine-like setae. Mesoprescutum with transverse, irregular row of 12 long, slen- der setae; mesoscutellum with transverse row of 8 long, slender setae and without spine-like setae. Metaprescutum with 18 long, slender setae; metascutellum with 8 long, slender setae, spine-like setae absent. Legs ( Fig. 11a–c ): Tarsal claws with enlarged apical process, 1 basoexternal seta, and 1 internal, preapical seta. Protarsal claw longer than mesotarsal and metatarsal claws. Coxa, trochanter, and tibiotarsus of all legs with many long, stout setae. Abdomen: Abdominal spiracle I subequal in size to prothoracic spiracle, 0.207 mm long and 0.316 mm wide, shorter than spiracles II–VII. Spiracles on segments II and VII subequal in size (0.237 mm long and 0.336 mm wide), slightly larger than spiracles on segment VII (0.306 mm long and 0.217 mm wide). Abdominal segment I on prescutum with 20 long, slender setae and 8 short, spine-like setae; subscutum with 4 long, slender setae and without short setae; scutum with about 4 short, spine-like setae and 28 long, slender setae; scutellum with about 38 short, spine-like setae and 4 long, slender setae. Abdominal segment II on prescutum with 4 long, slender setae and 28 short, spine-like setae; subscutum with 4 long setae and without short, spine-like setae; scutum with 12 long, slender setae and 36 short, spine-like setae; scutellum with 4 long, slender setae and 36 short, spine-like setae. Abdominal segment III on prescutum with 4 long, slender setae and 30 short, spine-like setae; subscutum with 4 long, slender setae and without short, spine-like setae; scutum with 12 long, slender setae and 43 short, spine-like setae; scutellum with 4 long, slender setae and 50 short, spine-like setae. Abdominal segment IV on prescutum with 4 long, slender setae and 32 short, spine-like setae; subscutum with 4 long, slender setae and with 1 short, spine-like seta; scutum with 10 long, slender setae and 54 short, spine-like setae; scutellum with 4 long, slender setae and 58 short, spine-like setae. Abdominal segment V on prescutum with 2 long, slender setae and 35 short, spine-like setae; subscutum with 4 long, slender setae and 1 short, spine-like seta; scutum with 12 long, slender setae and 58 short, spine-like setae; scutellum with 8 long, slender setae and 58 short, spine-like setae. Abdominal segment VI on prescutum with 4 long, slender setae and 38 short, spine-like setae; subscutum with 1 long, slender seta and 4 short, spine-like setae; scutum with 12 long, slender setae and 40 short, spine-like setae; scutellum with 12 long, slender setae and 40 short, spine-like setae. Abdominal segment VII with 2 rows of 16 slender, long setae mixed with 26 short, spine-like setae. Abdominal segment VIII with 2 rows each with 8 slender, long setae and 20 short, spine-like setae. Abdominal segment IX with 6 slender, long setae distributed irregularly mixed with 10 short, spine-like setae. Abdominal segment X with approximately 52 moderate to long, slender setae and 8 short, spine-like setae mixed. Pleural lobes with 4 long, slender setae; short, spine-like setae absent. All spiracular areas with 5 long, slender setae and 2 short, spine-like setae. Raster: Surface without palidia; campus with 4 slender, long setae; teges with 62 short setae that project toward superior anal lobe; barbula with 22 long, slender setae. Anal slit transverse. Dorsal body length approximately 75.98 mm (Fig. 12).

Pupae (6). Female ( Figs. 13 a– c). Length 32.0– 34.5 mm; greatest width 14.5–17.0 mm. Body elongate, oval, stout, exarate. Color dark reddish brown. Entire body with fine, velvety-gold vestiture. Head: Surface glabrous, bent sharply beneath thorax, mouthparts directed ventrally; antenna, labrum, mandibles, maxillae and palps discernible; antennal tecae expanded, stout, with apices rounded. Compound eyes sunken, scarcely visible, with 2 tubercles between eyes. Thorax. Surface glabrous. Form transverse, with wide, anteromedial, round apex, tubercle slightly defined. Mesonotum and metanotum well differentiated. Elytral and posterior wing tecae closely appressed, curved ventrally around body; elytral tecae extending to end of abdominal segment I; posterior wing tecae extending to middle of abdominal segment III. Protibia with 3 distinct teeth on external edge. Mesotibiae and metatibiae with inner and external spines well developed at apices. Abdomen: Segments III–X (ventral view) well defined. Segment VII slightly long than preceding and segment VIII 0.25 times longer than segment VII; segments VIII and IX fused. Segment X with small genital ampulla (female). Segments I–X (dorsal view) with well-defined, dioneiform organs between segments I–II, II–III, III–IV, IV–V, V–VI and VI–VII, the first strongly sclerotized. Pleural lobes rounded. Spiracle I elongate, with fine peritreme, covered by wing thecae; spiracles II–IV ovate, prominent, each with strongly sclerotized peritreme; spiracles V–VIII closed. Abdominal apex rounded, with fine, short setae.

Distribution. Homophileurus tricuspis is known from Mexico, Guatemala, Belize, Nicaragua, Venezuela, and Brazil ( Endrödi 1978), Costa Rica and Panama ( Ratcliffe 2003), and El Salvador and Honduras ( Ratcliffe and Cave 2006). The specimens in this study are a NEW COUNTRY RECORD for Colombia.

Natural history. Adults are usually encountered at lights or occasionally in rotten logs. Ratcliffe & Cave (2006) dissected an arboreal termite nest on Isla Roatán in Honduras and collected an adult H. tricuspis . Larvae in this present study from Potrero, Colombia ( Fig. 15) were found developing in the center of an abandoned termite nest in a debris midden ( Figs. 14 a–d). JCN observed strong stridulation by the adult female and vibrations by the larva when held in the hand. Larvae pupated in a cell they produced in the wall of the nest.

Luederwaldt (1911) reported H. luederwaldti and Actinobolus trilobus Luederwaldt living in the arboreal nest of two species of Nasutitermes Dudley termites and Actinobolus radians Westwood living in the epigeous nest of Cornitermes Wasmann termites in Brazil. The larvae of these beetles fed upon the nest itself, which could result in the partial or total destruction of the termite nest. Vanin et al. (1983) observed adults and larvae of H. luederwaldti in the arboreal nest of Microcerotermes Silvestre termites; pupal chambers were seen in the walls of the nest. Termitophily for certain species of Phileurini seems to be more common than previously recognized.

The adults of H. tricuspis are attracted to lights at night. This species ranges from sea level to 1800 m in elevation ( Ratcliffe 2003).

Figures

FIGURE 2. Epipharynx of Homophileurus tricuspis, third instar.

FIGURE 7. Hypopharynx of Homophileurus tricuspis, third instar, showing hypopharyngeal sclerome. FIGURE 8. Last antennomere, dorsal view of Homophileurus tricuspis, third instar, showing sensory spots. FIGURE 9. Last antennomere, ventral view of Homophileurus tricuspis, third instar, showing sensory spots. FIGURE 10. Prothoracic spiracle (a) and spiracular holes (b) of Homophileurus tricuspis, third instar.

FIGURE 13. Pupa of Homophileurus tricuspis. (a) ventral view; (b) Dorsal view; (c) lateral view; (d) ventral view of last abdominal segment of male showing genital ampulla; (e) ventral view of last abdominal segment of female showing genital ampulla.

FIGURE 11 a – c. Lateral view of claw of protarsus, mesotarsus, and metatarsus of Homophileurus tricuspis, third instar. FIGURE 12. Lateral view of Homophileurus tricuspis, third instar.