Atractocerus brasiliensis (Lepetelier & Audinet-Serville, 1825)

Casari, Ymexylidae Tractocerinae Sônia A. & Albertoni, Fabiano F., 2013, First Instar Larva Of Atractocerus Brasiliensis (Lepeletier & Audinet-Serville, 1825) (Lymexylidae, Atractocerinae, Papéis Avulsos de Zoologia 53 (27), pp. 359-372 : 359-372

Atractocerus brasiliensis

Eggs ( Fig. 42 ): length: 1.8-2.0 mm; width 0.6-0.8 mm.

Cream, elliptical, without ornamentation.

The eggs were laid in two batches of about 80 eggs each, among a gumming whitish substance. The majority of eggs did not eclode and 23 were fixed. After eclosion the larvae stayed for a short time moving among the egg shells and the gumming substance ( Figs. 43-45 ).

First instar larva ( Figs. 1 , 3-15 , 25-41 , 43-47 ): length: 2.0-2.1 mm

Elongate, cylindrical, slightly flattened, with apex narrowed and upwardly directed. General coloration cream ( Figs. 43-47 ); head yellowish and mandibles brownish with black apices; labrum brownish; dark-brown transverse band at base of pronotum, at middle of meso- and metanotum and on segments I-VIII (some divided at middle); abdominal segments with a dark-brown lateral patch on each side; segment IX very sclerotized, ferrugineous with darker apex; stemmata black ( Figs. 45-46 ). General pubescence yellowish and very long; microspines in specific areas of thorax and abdomen ( Figs. 1 , 25-26, 28 , 45-47 ).

Head ( Figs. 3-4 , 25, 27, 29 , 43, 45-47 ) hypognathous partially retracted into pronotum, visible dorsally; oval, heavily sclerotized. Coronal suture long, straight; endocarina as long as coronal suture; frontal arms not well defined, visible like a pale band with undefined end. Frons with ten pairs of frontal setae (fs) of varied sizes, some longer than half of head length; dorsally each side with a row of five short dorso epicranial setae (des) and two longest near stemmata. Five black stemmata on each side, behind antennal base: two basely located and three in a semi-circle above anterior marginated by several setae. Antennae ( Figs. 3 , 10-11 , 25, 27 , 30-32 ) minute, posterolateral to base of mandibles, in a groove that comes frontally from anterior stemmata ( Figs. 25, 27 , 23 , 32 ); invaginated and surrounded by an antennifer-like structure with very long distal projections ( Figs. 30-32 ), visible only in SEM; antennifer membranous, well developed; two antennomeres: basal wider than long, bearing at apex a well-developed membranous sensorial appendix (sa), two long setae (one longest) and two trichobothria; distal antennomere narrow, shorter than sensorial appendix, inserted laterally at apex of basal antennomere, side by side with sensorial appendix, bearing four or five long setae at apex (two widest) and one trichobothrium visible only in SEM. Frontoclypeal (fcls) suture ( Figs. 3 , 9 , 27 ) well visible only at middle between two basal setae of clypeus. Clypeus (cl) narrow, transverse with fore angles rounded, bearing three pairs of long setae (one pair longest). Labrum (lbr) ( Figs. 3 , 9 , 27 ) narrow, transverse, proximal margin as wide as distal margin, distal margin slightly rounded, bearing ten very long setae, more than twice as long as labrum length: six at anterior margin, two near fore angles and two at base. Epipharynx ( Fig. 12 ) slightly prominent ventrally, becoming slightly raised longitudinally at middle; distal margin slightly rounded with three long setae (one sinuous) on each side and four at middle; each side of raised area with microsetose band convergent medially, continuous with longitudinal median sclerite. Mandibles ( Figs. 13-15 ) symmetrical, heavily sclerotized, broad, short with wide apex and subapical rounded lobe; molar area weakly developed with rows of irregular teeth (mit); two lateral setae. Maxilla ( Figs. 8 , 33-34 ) elongate; cardo (crd) subtriangular bearing three moderately long setae; stipes elongate bearing one short seta at base and eight long setae (two represented by punctures); palpifer with one long palpiferal seta (pfs); mala elongate, longer than palpus, with five long malar setae (ms) at apex; palpus with two palpomeres: basal as wide as long with two long setae, distal elongate, narrower than basal with several peg-like sensillla at apex. Labium ( Fig. 8 ) elongate; prementum short, transverse, basal margin strongly prominent at middle, making basal half triangular; palpiger with one long and one tiny seta and one campaniform sensillum; palpus with two palpomeres: basal transverse; distal elongate with one campaniform sensillum near base and several elongate setae at apex; ligula elongate, trapezoidal, longer than palpi, with two setae at apex; mentum elongate, narrowed on distal third; distal margin strongly notched at middle with four pairs of long setae and one pair of campaniform sensilla.

Prothorax ( Figs. 1 , 25, 28 , 45-46 ) longer than meso- and metathorax together; pronotum with sharpened and rounded microspines and sparse short setae on anterior and lateral irregular bands; dark-brown band at basal third; each side of darker band with two very long and three moderately short setae (two short represented by punctures) ( Fig. 1 ). Mesoand metathorax similar: transverse, band-like, each with one dark-brown transverse dorsal band and one patch of microspines on each side; mesothorax with one long and three short dorsolateral setae and laterally one very long and one short setae; metathorax with three short dorsolateral setae and one very long lateral. Each side of mesothorax with one ventrolateral anterior spiracle. Legs ( Figs. 1 , 7 , 40-41 ) increasing in size from anterior to posterior, inserted distant from middle line of venter; coxa elongate with several setae of varied sizes; trochanter subtriangular; femur and tibia elongate; femur wider and as long as tibia; trochanter, femur and tibia with setae of varied sizes and microspines near ventral region; one very long femoral spatulate seta (fss); pretarsus claw-like with two setae near base.

Segments I-VIII ( Figs. 1 , 25-26 , 45-47 ) transverse, band-like, dorsally with dark-brown transverse dorsal band and one patch each side; dorsally with microspines distributed in different ways, increasing in size to apex direction; each side with dorsolateral rounded spiracle, barely or little visible, near a crescent-like scar and two or three short setae (some represented by punctures) below them; each side with one lateroventral short seta and one longest ventral seta. Segments I-IV dorsally with microspines in a tranverse irregular band at middle, with two short setae each side and one longest pair dorsally near middle (except segment I). Segments V-VIII dorsally with transverse, narrow, sclerotized, dark-brown band with microspines at distal margin; with two short setae each side and one longest dorsal pair near middle of darker band. Segment IX ( Figs. 1 , 5 , 35-38 , 47 ) strongly sclerotized, concave with apex darker, tooth-like upwardly directed; concavity marginate by microspines and long setae; two pairs of moderately long setae dorsally, inside concavity, near apex. Segment X ( Figs. 6 , 38-39 ) rounded, ventral, globose, with two lobes, each marginated by seven teeth; one distal sclerotized microspined patch, surrounding anal opening.

Material examined: BRAZIL. Goiás: Goiânia, Jardim Balneário Meia Ponte (16°36’37.84”S, 49°17’40.68”W). 14.vii.2011, N.A. da Silva & F.F. Albertoni cols., 1 adult, 23 eggs, 4 first instar larvae (one dissected and one gold covered for SEM) ( MZSP) , 8 deutonymphs mites (Uropodoidea). São Paulo: Salesópolis, Estação Biológica de Boracéia , (23°39’15,63”S, 45°53’22,38”W) 850 m, 25.ii.2012, F.F. Albertoni leg, 1 adult, 5 deutonymphs mites (Uropodoidea) ( MZSP) .

Biological notes

As already observed by Fulmek (1930), the eggs and just ecloded first instar larvae, under laboratory conditions, remained among the whitish viscous substance; they were very difficult to individualize or clean. This is evident in some photos, where the larvae are very dirty ( Fig. 47 ).

Simmonds (1956) reported that the eggs were laid in freshly felled mango logs; they were laid in batches with a very “viscous fluid”, which also exuded at times from the female abdomen when no eggs were being laid. According to him, this fluid remained extremely viscous for at least two weeks, even after the eggs had hatched.

After the eggs had hatched, the first instar larvae remained together with the eggshells ( Figs. 43-45 ). According to Simmonds (l.c.), they ate the empty eggshells in the first 24 hours, becoming very active after that. According to Wheeler (1986), during the contact of the larvae with siblings and eggs, transference of fungal spores onto the integument would occur. The female would emerge bearing spores in vaginal pouches, eventually depositing them in the slimy matrix with eggs.

According to Lyngnes (1958) (apud Grandi, 1962), the first instar larva of Hylecoetus dermestoides feeds on fungi that grow at tunnel walls, especially Ascomycete, Endomyces hylecoeti Neger. He stated that segment IX of the first instar larva is used to push the frass outside of the tunnel. This protects the larva against insect attacks and also transports small particles, like fungi spores, to inside the tunnel. The modified segment IX, as in mature larva, could be used for the same purpose, as well as to excavate when the larva retreats. Casari & Teixeira (2011) observed mature larvae of Atractocerus brasiliensis pushing frass outside of the tunnel.

FFA observed a curious behavior in an adult collected in Estação Biológica de Boraceia (Salesópolis, São Paulo). When touched or held, the adult curved his abdomen upwards and expanded the pleura of visible segments 4 and 5, as shown in Fig. 49 . The same adult also would rest with abdomen suspended, ( Fig. 52 ) a similar behavior that was observed and illustrated by Casari & Teixeira (2011) when the adult was observed resting upside down on the ceiling of a cage with the abdomen apex downwardly directed.

Several mites ( Fig. 50 ) were found on the abdominal tergites of both specimens collected in Goiânia and Salesópolis. The mites are deutonymphs of the superfamily Uropodoideae , presumably of the family Trematuridae . The deutonymphs were attached to the beetle integument by the abdomen apex. Lindquist et al. (2009) suggested that Trematuridae possibly feed on fungi and organic debris of insects galleries. Near the body of one mite from Goiânia were found spores that resemble ascomycetes conidia ( Fig. 51 , red arrow) (Larissa Trierveiler, pers. com.) and all analyzed mites from Goiânia had a distinct fungi spore of another species ( Fig. 51 , black arrow) (Larissa Trierveiler, personal communication).

Figures

FIGURES 42‑46: Atractocerus brasiliensis (Lepeletier & Audinet-Serville, 1825). (42) eggs; (43-45) eggs, eggshells and newly ecloded larvae; (46) first instar larva (lateral).

FIGURES 1‑2: Atractocerus brasiliensis (Lepeletier & Audinet-Serville, 1825). Larva lateral: (1) first instar; (2) mature (from Casari & Teixeira, 2011).

FIGURES 3‑7: Atractocerus brasiliensis (Lepeletier & Audinet-Serville, 1825). First instar larva: (3-4) head (dorsal, lateral); (5) segments VI-IX (dorsolateral); (6) segments VIII-X (ventral); (7) metathoracic leg (lateral). des = dorso epicranial setae, fs = frontal setae, fss = femoral spatulate seta.

FIGURES 8‑15: Atractocerus brasiliensis (Lepeletier & Audinet-Serville, 1825). First instar larva: (8) maxillo-labial complex; (9) clypeus and labrum; (10-11) right antenna (dorsal, ventral); (12) epipharynx; (13-15) right mandible (ventral, dorsal, mesal); cl = clypeus, crd = cardo, fcls = fronto clypeal suture, lbr = labrum, mit = molar irregular teeth, ms = malar setae, pfs = palpiferal setae, sa = sensorial appendix.

FIGURES 25‑29: Atractocerus brasiliensis (Lepeletier & Audinet-Serville, 1825). First instar larva (SEM): (25) habitus (lateral); (26) first abdominal segments (lateral); (27) head (frontal); (28) fore angle of pronotum with sharpened and rounded microspines; (29) head (fronto-lateral).

FIGURES 30‑34: Atractocerus brasiliensis (Lepeletier & Audinet-Serville, 1825). First instar larva (SEM): (30) head (latero-posterior); (31-32) antenna (dorso-anterior, latero-posterior); (33) right maxillary palp (lateral); (34) right maxilla (lateral).

FIGURES 35‑41: Atractocerus brasiliensis (Lepeletier & Audinet-Serville, 1825). First instar larva (SEM): (35) segments VI-IX (dorsal); (36) apex of segment IX (dorsal); (37) detail of lateral margin of segment IX (dorsal); (38) segments IX-X (ventro-lateral); (39) segment X (ventro-lateral); (40) right legs; (41) median right leg with spatulate seta.

FIGURES 16‑24: Atractocerus brasiliensis (Lepeletier & Audinet-Serville, 1825). Mature larva (from Casari & Teixeira, 2011): (16) clypeus and labrum; (17) epipharynx; (18) mandible (dorsal); (19) maxilla (ventral); (20) labium (ventral); (21-22) head (dorsal, lateral); (23) prothoracic tarsal claw; (24) metathoracic leg (lateral).

FIGURES 47‑53: (47-49, 52-53) Atractocerus brasiliensis (Lepeletier & Audinet-Serville, 1825). (47) first instar larva (dorsolateral). Adult female: (48) dorsal; (49, 53) lateral; (52) abdomen (dorsolateral) with Uropodoidea deutonymphs presumably Trematuridae (ellipses). (50) deutonymph of Uropodoidea mite with fungi spores (black arrows); (51) conidium (red arrows) nearby deutonymph and fungi spores (black arrows).