Homophileurus integer (Burmeister)

Ratcliffe, Brett C. & Skelley, Paul E., 2011, Description Of The Larva Of Homophileurus Integer (Burmeister, 1847) (Coleoptera: Scarabaeidae: Dynastinae: Phileurini), With Notes On Biology And A Key To The Known Larvae Of New World Phileurini, The Coleopterists Bulletin 65 (3), pp. 297-304 : 298-304

Homophileurus integer (Burmeister) , third instar

( Figs. 1–19 )

Material Examined. Four larvae in the third instar with the following data: “ SURINAME: Para District, Zanderij, near Guesthouse, N05°27.5′, W055°13.0′, 8-Feb-2010, P. Skelley, W. Warner, C. Gillett, in arboreal termite nest w/adults, see pictures”. These larvae were collected in association with two adults (1 male, 1 female) in pupal cells .

Description. Dorsal body length approximately 52.2 mm. Cranium ( Figs. 1–2 ): Width of head capsule 6.6–6.8 mm. Color yellowish brown. Surface moderately punctate on frons (F) and labrum (L), epicranium (E) and postclypeus (PSC) less densely punctate, preclypeus (PC) less sclerotized and cream-colored. Epicranial suture (ES) and frontal suture (FS) distinct. Frons: Surface with 1 exterior frontal seta (EFS) and 3 posterior frontal setae (PFS) on each side and with 4 anterior frontal setae (AFS). Each anterior angle with 2 setae (AAS). Epicranium on surface with 3 dorsoepicranial setae (DES), about 15 epicranial setae (ES) distributed irregularly, 2 anterior frontal setae (AFS), and 8 paraocellar setae (POS) on each side. Ocellus (O) present. Clypeus: Form trapezoidal. Surface of postclypeus with 2 external clypeal setae (ECS) on each side and 2 anterior central setae (CS). Labrum: Surface slightly asymmetrical, with 6 posterior labral setae (PLS) and 3 posterolateral labral setae (PLLS) on each side. Epipharynx ( Fig. 3 ): Form transversely suboval, asymmetrical, left lateral margin slightly angulate. Haptomeral process (HP) absent. Right and left chaetoparia (CPA) each with 65 setae. Acroparia (ACR) with 20 long, stout, slightly curved setae. Corypha (CO) with 9 long, stout, slightly curved setae. Right acanthoparia (ACP) with 7 short, curved, spine-like setae; left acanthoparia with 9 short, curved, spine-like setae. Pedium (P) longer than wide, without setae. Dexiotorma (DX) narrow, elongate. Laeotorma (LT) shorter than dexiotorma. Pternotorma (PTT) rounded. Haptolochus (HL) lacking setae. Sclerotized plate (SP) of right nesium (NR) slender, elongate. Sense cone (SC) on left nesium (LR) a well-sclerotized, rounded plate. Crepis not evident. Left mandible ( Figs. 4, 6 ): Form falcate. Scissorial area with blade-like, apical tooth (S 1 + S 2 fused), separated from S 3 by scissorial notch (SN), S 4 below notch. Scrobis (SCR) with 11 slender, long setae. Acia (AC) well-developed, acute, with 8 basolateral setae. Ventral surface with elongate-oval stridulatory area (STA) with about 50 narrowly separated, subparallel ridges. Ventral process (VP) large, rounded. Brustia (BR) with 11 long setae. Molar lobe (ML) large, weakly subdivided. Postartis (PTA) large, rounded. Right mandible ( Figs. 5, 7 ): Form falcate. Scissorial area with blade-like, apical tooth (S 1 + S 2 fused), separated from S 3 by scissorial notch (SN), S 4 below notch. Scrobis (SCR) with 9 long setae. Acia (AC) well developed, with 6 basolateral setae. Dorsal surface with 2 long setae well below base of S 3. Preartis (PA) distinct, concave. Ventral surface with elongateoval, stridulatory area (SA) with about 47 narrowly separated, subparallel ridges. Ventral process (VP) well-developed, broadly rounded. Ventral process (VP) large, rounded. Brustia (BR) with 5 long setae. Calx (CA) large, with 5 basolateral setae (BLS). Molar area with 6 ventral molar setae (VMS). Molar crown with 3 large lobes (M 1–3). Postartis (PTA) large, rounded. Maxilla and labium (ventral view, Fig. 8 ): Galea (GA) and lacinia (LAC) fused, forming mala (MA). Mala with large uncus (UN) at apex and 3 subterminal unci, basal uncus slightly separated from previous 2. Maxillary palpus (MP) 4-segmented, apical segment twice as long as previous segment. Cardo ( CAR) subdivided into 3 sclerites. Mentum subdivided into 3 sclerites: postmentum (PMP) and prementum (PM 1–2). Labial palpus (LP) with 2 seg- ments. Maxilla and labium (dorsal view, Fig. 9 ): Stridulatory area with row of 7 stridulatory teeth (SD), teeth becoming increasingly smaller basally. Glossa with 32 long setae and 40 short setae. Hypopharyngeal sclerome (HSC) asymmetrical, truncate process (TP) prominent, elevated. Lateral lobes (LL) with about 16 long setae each. Antenna: Antenna (A) 4-segmented, segments 1–2 subequal in length, each slightly longer than segment 3; terminal segment about half length of segment 2. Terminal segment on dorsal surface with 5 dorsal sensory spots (DSS), ventral surface with 8 ventral sensory spots (VSS) ( Fig. 10 ), apex with 1 sensory spot. Thorax: Prothoracic spiracle ( Fig. 11) 0.7 mm long, 0.5 mm wide; respiratory plate (RSP) light brown, C-shaped, spiracular bulla (BU) rounded, barely elevated; respiratory plate with about 40 regularly edged holes across diameter at middle. Dorsum ( Fig. 12) of pronotum and prescutum II and III (PRSC) each with transverse row of long, slender setae. Legs ( Fig. 13a–f): Coxa (CX), trochanter (TR), femur (FE), and tibiotarsus (TT) of all legs with numerous, long, stout setae. Tarsal claws (CL) falcate, with 1 basoexternal seta and 1 internal, preapical seta. Protarsal claw longer than middle and posterior tarsal claws. Abdomen: Abdominal spiracle ( Fig. 14) slightly larger (0.8 mm long, 0.6 mm wide) than prothoracic spiracle, all abdominal spiracles subequal in size. Abdominal segments I-VII each with transverse row of 35–40 short, spine-like setae. Abdominal segments VIII-X with sparse, minute setae. All spiracular areas with 5 long, slender setae. Raster: Surface ( Fig. 15) without palidia. Campus (C) with 6 slender, long setae. Teges (T) with 60 short, spine-like setae projecting towards anal slit (ASL). Anal slit transverse.

Distribution. Homophileurus integer is known from French Guiana, Trinidad, and Brazil ( Endrödi 1978, 1985). The specimens in this study represent a not-unexpected new country record for Suriname.

Biology. Adults of H. integer ( Fig. 16 ) are usually encountered at lights. Lüderwaldt (1911) reported H. luederwaldti and Actinobolus trilobus Lüderwaldt living in the arboreal nest of two species of Nasutitermes termites as well as Actinobolus radians Westwood living in the epigeous nest of Cornitermes termites in Brazil. The larvae of these species fed upon the nest itself which could result in 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 termites; pupal chambers were seen in walls of the nest. Ratcliffe and Cave (2006) dissected an arboreal termite nest on Isla Roatán in Honduras and collected an adult H. tricuspis . Neita and Ratcliffe (2011) reported larvae and pupae of H. tricuspis from an abandoned termite nest in Colombia, where they were developing in the center of the nest in a debris midden. Neita noted strong stridulation in the adult female and could feel the vibration of the larva when held in the hand. Larvae pupated in a cell they produced in the wall of the nest.

The larvae of H. integer were found in an arboreal nest of Microcerotermes arboreus Emerson ( Isoptera : Termitidae : Termitinae ) ( Figs. 17–18 ). This nest was about 30 cm in diameter and located approximately one meter above the ground in a wet savannahwoodland. The nest was chopped open with a machete to reveal a damp interior full of beetle frass and larvae ( Fig. 19 ). Pupal cells, as well as some remaining termites, were located near the nest exterior. Whether the beetles caused the nest to decay and the termites to decline, or whether the beetles were opportunistic in a previously damaged nest remains unknown. Numerous additional nests were surveyed, but no additional beetles or similarly damaged nest in decline were found. The larvae of H. integer vibrated when held firmly in hand simi- lar to that observed for H. tricuspis as described in Neita and Ratcliffe (2011).

It is becoming increasingly clear that Homophileurus species inhabit termite nests in which the larvae develop while feeding on the walls of the nest or in the debris midden in the center of the nest.

KEY TO THE THIRD INSTARS OF NEW WORLD PHILEURINI (modified from Neita and Ratcliffe 2011)

1. Anterior frontal setae absent.........................2

1′. Anterior frontal setae present.........................7

2. Lateral margins of labrum broadly rounded, not angulate (southern Brazil, Paraguay) ....... ............ Trioplus cylindricus (Mannerheim)

2′. At least 1 lateral margin of labrum angulate......3

3. Left lateral margin of labrum angulate.........4

3′. Left and right lateral margins of labrum angulate.........................................................6

4. Abdominal spiracle I smaller than spiracles II-VII. Last segment of antenna with 5 dorsal sensory spots ( Colombia)................................... ..... Hemiphileurus elbitae Neita and Ratcliffe

4′. Abdominal spiracles similar in size. Last segment of antenna with less than 5 dorsal sensory spots......................................................5

5. Last segment of antenna with 2 dorsal sensory spots. Inner margin of left mandible, distad of molar area, with short, rounded tooth (Hispaniola) ........................................... ........................ Hemiphileurus dispar Kolbe

5′. Last segment of antenna with 3–4 dorsal sensory spots. Inner margin of left mandible, distad of molar area, with prominent, triangular tooth ( USA, Mexico)............................ ................... Hemiphileurus illatus LeConte

6. Maxilla with a row of 7 truncate, stridulatory teeth. Inner margin of left mandible, distad of molar area, with prominent, triangular tooth (North to South America, West Indies) ......... ........................... Phileurus valgus (Olivier)

6′. Maxilla with a row of 6 conical, stridulatory teeth. Inner margin of left mandible, distad of molar area, with short, rounded tooth ( Uruguay, Brazil) ............................................ .... Archophileurus fimbriatus (Burmeister)

7. Ocelli present................................................8

7′. Ocelli absent (South America) ....................... .............. Archophileurus vervex Burmeister

8. Protarsal claw longer than meso- and metatarsal claws....................................................9

8′. Protarsal claw similar in size to meso- and metatarsal claws..........................................12

9. Anterior clypeal setae absent......................11

9′. Anterior clypeal setae present....................10

10. Terminal segment of antenna with 2–3 dorsal sensory spots ( Brazil) ..................................... ................. Actinobolus trilobus Lüderwaldt

10′. Terminal segment of antenna with 5 dorsal sensory spots (northeastern South America) ........ Homophileurus integer (Burmeister)

11. Lateral margins of labrum broadly rounded, not angulate. Left hypopharyngeal lobe with 11 lateral setae ( Brazil, Paraguay).................. ......... Homophileurus luederwaldti (Ohaus)

11′. Left lateral margin of labrum angulate. Left hypopharyngeal lobe with 20 lateral setae ( Mexico to Brazil) .......................................... ...................... Homophileurus tricuspis Prell

12. Laephoba with 17 slender, short setae. Maxilla with a row of 9 stridulatory teeth ( French Guiana, Brazil)................................................ ....................... Phileurus affinis Burmeister

12′. Laephoba with 11 slender, short setae. Maxilla with a row of 7 stridulatory teeth ( Mexico to Paraguay).................. Phileurus didymus (L.)

Figures

Figs. 1–3. Homophileurus integer, third instar. 1) Cranium, frontal view; 2) Cranium, lateral view. A-antenna; AAS-anterior angle setae; AFS-anterior frontal setae; DES-dorsoepicranial setae; E-epicranium; ECS-exterior clypeal setae; EFS-exterior frontal setae; ES-epicranial suture; F-frons; L-labrum; O-ocellus; PC-preclypeus; PFS-posterior frontal setae; PLS-posterior labral setae; PLLS-posterolateral labral setae; POS-paraocellar setae; PSC-postclypeus; 3) Epipharynx. ACP-acanthoparia; ACR-acroparia; CO-corypha; CPA-chaetoparia; DX-dexiotorma; HL-haptolochus; HP-haptomeral process; LT-laeotorma; NL-left nesium; NR-right nesium; P-pedium; PTT-pternotorma; SC-sense cone; SP-sclerotized plate.

Figs. 4–7. Homophileurus integer, third instar. 4–5) Left and right mandibles (dorsal view); 6–7) Right and left mandibles (ventral view). AC-acia; BLS-basolateral setae; BR-brustia; CA-calx; M1–3- lobes of molar crown; ML-molar lobe; PA-preartis; PTA-postartis; S1–4-scissorial teeth; SCR-scrobis; SN-scissorial notch; STA-stridulatory area; VMSventral molar setae; VP-ventral process.

Figs. 8–10. Homophileurus integer, third instar. 8) Maxillae and labium, ventral view; 9) Maxillae and labium, dorsal view. CAR-cardo; GA-galea; GL-glossa; HSC-hypopharyngeal sclerome; LAC-lacinia; LL-lateral lobe; LP-labial palpus; MA-mala; MP-maxillary palpus; PMP-postmentum; PRM1–2-prementum sclerites; SD-stridulatory teeth; ST-stipes; TP-truncate process; UN-uncus. 10) Last antennnomere (ventral view). VSS-ventral sensory spots.

Figs. 16–19. 16) Homophileurus integer, adult; 17) Arboreal nest of Microcerotermes arboreus in Suriname, with machete cuts visible on nest; 18–19) Larvae of H. integer in situ in the termite nest.