Ora semibrunnea Pic, 1922

Jorge, Gabrielle, Libonatti, María Laura, Benetti, Cesar João & Hamada, Neusa, 2019, Description of the mature larva and pupa of Ora semibrunnea Pic (Coleoptera: Scirtidae) with notes on its biology, Zootaxa 4551 (1), pp. 53-66 : 56-62

Ora semibrunnea Pic, 1922

Ora semibrunnea Pic 1922: 5 [ Brazil]; Libonatti 2015: 89 [redescription].

Material examined. Brazil , Amazonas state, Autazes county, São Longuinho lake (3°34'55.6"S 59°08'21.9"W) 07/iv/2017, leg. Jorge, GM, Benetti , CJ & Amora, G [1 ♀, 1 larva]; Iguapenú lake (3°33'3.0"S 59°9'49.3"W) 07/iv/ 2017, leg. Jorge, GM, Benetti, CJ & Amora, G [1♂, 8 larvae]. Careiro da Várzea county : Laguinho do bodó lake (3°17'14.1"S 59°52'50.0"W) 06/iv/2017, leg. Jorge, GM, Benetti, CJ & Amora, G [7 ♂, 2♀, 2 pupae, 2 larvae]. Iranduba county : lake near the Caldeirão road Km 3 (3°12'39.1"S 60°12'30.5"W) 14/xii/2016, leg. Jorge, GM, Amora, G & Colpani, D; 16/iii/2017, leg. Jorge, GM & Benetti, CJ [11 ♂, 7 ♀, 9 larvae]; Limão lake (3°11'2.1"S 060°21'5.5"W) 20/viii/2017, leg. Jorge, GM [1 ♀]; Catalão lake (03°9'52.6"S 59°54'23.1"W) 11/vi/2017, leg. Jorge, GM, Benetti, CJ & Santana L; 16/vi/2017, leg. Jorge, GM & Santana L [22 ♂, 19 ♀, 10 pupae, 71 larvae]. Itacoatiara county : Poranga lake (3°8'25.8"S 58°27'23.7"W) 23/v/2017, leg. Jorge, GM, Benetti, CJ & Santos CRN [4 ♂, 3 ♀, 2 pupae, 7 larvae]; Centenário lake (3°8'25.7"S 58°27'23.4"W) 23/v/2017, Jorge, GM, Benetti, CJ & Santos CRN [1 larvae]; Canaçari lake (3°6'35.5"S 58°25'18.4"W) 24/v/2017, leg. Jorge, GM, Benetti, CJ & Santos CRN [2 ♀, 1 pupa, 6 larvae]. Manaus county : Remanso do Boto lake , Puraquequara (2°57'54.5"S 60°2'32.7"W) 13/ xii/2016, leg. Jorge, GM, Amora, G & Colpani, D [3 ♂, 12 larvae]; 16/iii/2017, leg. Jorge, GM & Benetti, CJ; lake near the Tarumã road (3°4'6.9"S 59°51'3.7"W) 30/iv/2017, leg. Jorge, GM, Benetti, CJ & Santana L [3 ♂, 12 larvae].

Description, mature larva. Habitus. TL 8.75–9.00 mm (n=2). Coloration in dorsal view dark brown with light small spots; in ventral view, light brown with abdomen a little darker ( Fig. 4 A–B).

Head. Head length 0.80–1.04 mm, head width 1.00– 1.10 mm (n=2). Head bowl-shaped, lateral edges with a series of short, thin setae and three long anterior setae ( Fig. 4 C–D). Antennae long, almost as long as body, scape stout, twice as long as wide, slightly curved outwards, usually with four long and about 14 short setae and a group of short setae on ventral region; pedicel straight, longer and thinner than scape, 3 × as long as wide, with one strong seta at apex in ventral view; flagellum long, with about 150 flagellomeres ( Fig. 5A ). Clypeolabrum V-shaped, lobes poorly developed, inner edges almost meeting at their bases, slightly oval at apex in dorsal view; lateral edges without setae; dorsal surface covered by fine, short, sparse setae and four basal setae; palisade setae numerous, thin and long; spine with one small spine on outer edge; ventral surface with five thin setae curved inwards ( Fig. 5B ); about 14 setae on each lobe; above the cone teeth with a group of short thin microtrichia curved upward ( Fig. 5C ). Mandibles symmetric, broad, with apex rounded; with a row of 16 long setae on outer edge, a group of small microtrichia on dorsal surface near the base, a brush with 12–14 long, branched setae and several short thin setae arranged in two areas slightly separated from ventral surface, next to the inner edge ( Fig. 5 E–F). Maxilla moderately long; galea with oval apex and dense bristle brush with single setae; lacinia triangular-shaped, with 7–8 short, rectangular-shaped teeth. Maxillary palpi long, four-segmented; segment 1 slightly more robust than others, 4× as long as wide, with some sparse setae; segment 2 with fewer setae than segment 1, 3× as long as wide; segment 3 thin and long, with a few sparse setae, on dorsal surface, and five oval areas of sensory organs horizontally arranged in ventral surface; segment 4 with thin sparse setae and a set of sensory organs at apex ( Figs. 5D ; 6 A–C). Hypopharynx long, socket and keel sclerites contiguous, the basal pair of pores small, positioned laterally to each other; tooth bristles broad, with 4–6 teeth on inner edge; stiff plate with a few fine setae; with 2–3 pairs of comb teeth; claw apparatus with an inner row of 20 pairs of long inwardly curved teeth; cushion area triangle-shaped; ‘hand-like structure’ each with 6–7 long fingers ( Fig. 6 F–G).

Thorax. Several fine setae with different lengths on lateral edge and few setae on dorsal surface; prothorax more expanded than the other segments, twice as wide as long; mesothorax slightly wider than the other segments, mesothorax and metathorax similar in length. Legs short, with strong spines; fore leg shorter and thinner than others, with a well-developed tibiotarsal organ with pectinate setae ( Fig. 6 D–E); femur with a row of about 16 long thin spine-like setae on ventral surface; tibia with about 20 thin setae on ventral surface; tarsal claw with two spines ( Fig. 6E ).

Abdomen. Gently and gradually tapered posteriorly; segments I–VII with some long, thin sparse setae, several fine and short setae and a row of robust short setae on lateral and posterior edges of tergites and sternites. Tergite VI with strong spine-like setae on lateral and posterior edges, and with fine, sparse, short and long setae ( Fig. 7A ); tergite VIII trapezoid-shaped with posterior apex W-shaped, lateral sclerite slightly rectangular, with anterior apex triangular, moderately covered by setae of different sizes on dorsal surface and one pair of long setae on lateroapical angles ( Fig. 7B ); tergite IX arch-shaped, with a simple row of setae of different lengths on anterior edge, with sparse short setae on dorsal surface, and with an apical pair of long strong setae projected near the lateral edges; posterior edge of tergite between apical setae rounded ( Fig. 7C ); sternite VIII trapezoidal-shaped, 3 × as wide as long, with short setae on latero-dorsal edge, without setae on the anterior edge, and some long setae and a row of setae on the posterior edge ( Fig. 7D ); sternite IX semicircular, with three pairs of long setae on lateral edges, without setae on anterior edge, with several short setae on the lateral edge and with short fine and long strong setae on dorsal surface ( Fig. 7E ). Spiracle apparatus relatively narrow, upper apical lobes triangular with crenulated edges; surface reticulate, inner atrium, short and broad ( Fig. 10C ); with four simple anal lobes.

Description, pupa. TL 3.8 mm (n=1), well sclerotized, dark brown with small light spots along the body, especially on the abdomen ( Fig. 8 A–B). Head strongly sclerotized with fine setae and well-marked ecdysial line; without pronotal processes [= spines of Yoshitomi (2005)]. Pronotum with lateral edges modified into siphons ( Fig. 8 C–D), light-yellow, bearing hydrophobic setae at the apex and several microtrichia on the inner region ( Fig. 8 C– D); pterothecae with few short sparse setae and a row of long setae on edges. Each abdominal segment with an unaligned row of thin setae and seven transverse light spots on posterior edge, with small granules, in dorsal view ( Fig. 9A ); a group of setae on each latero-posterior edge of each segment; each abdominal segment covered by small granules and four glabrous regions, in ventral view ( Fig. 9B ); unaligned row of thin setae on posterior edge and a group of setae on central region of each abdominal segment. Sexual dimorphism present; male attachment organ with short median lobe and with two small opposite hooks with short pointed apical processes ( Fig. 9D, F ); female attachment organ also with a short median lobe, with hooks and short apical processes hook-shaped ( Fig. 9C, E ).

Biology and habitat. The eggs of this species are not known. Larvae and pupae were observed in macrophyte banks associated with roots of Salvinia auriculata and stems of Marsilea sp. in natural lakes, with riparian vegetation and exposed to sun ( Fig. 2 A–F). Larvae maintained in the laboratory passed through at least six instars in 65 days. Before pupation, the mature larva orients its head downwards and contacts the water surface with the tergites and sternites VIII and IX with hydrophobic setae. During this process, the pre-pupa (period during which the larva no longer feeds, is immobile and remains connected to the water surface) breathes atmospheric air using the spiracle apparatus located between the tergites and sternites VIII and IX ( Fig. 10 A–C). After one day, the pupa leaves the last-instar exuviae but remains attached to the thoracic portion of the exuviae by the attachment organ. The pupa is aquatic, and it is connected to atmospheric air by a pair of pronotal siphons, and it remains suspended under the water surface with the larval exuviae attached ( Fig. 10 D–E). The attached larval exuviae connected with atmospheric air is important because the submerged pupae can remain floating just under the water surface. Under laboratory conditions we observed that when the exuviae are removed the pupa sinks and dies. The pupal stage lasts three to four days (n=85). After emergence, the adult rests on the surface of macrophyte leaves ( Fig. 10F ).

Distribution. Brazil: Amazonas state. Argentina: Buenos Aires, Chaco, Corrientes, Santa Fe and Santiago del

Estero provinces.

Figures

FIGURE 2. Some habitats of Ora semibrunnea. A) In Amazonas state: Tarumã Lake, Manaus County; B) Iguapenú Lake, Autazes County; C) Canaçari Lake, Itacoatiara County; D) macrophyte Salvinia auriculata (Salviniales: Salviniaceae); E) Catalão Lake, Iranduba Lake; F) example of the substrate used by Ora semibrunnea, stem of Marsilea sp. (Salviniales: Marsileaceae).

FIGURE 4. Ora semibrunnea larva. Habitus, A) dorsal view, B) ventral view. Head and prothorax, C) dorsal view, D) ventral view. Scales: A, B: 2 mm; C, D: 0.5 mm.

FIGURE 5. Mouthparts and antenna of Ora semibrunnea larva. A) Left antenna, dorsal view; B) clypeolabrum, dorsal view; C) clypeolabrum, ventral view with epipharynx detailed; D) left maxilla, dorsal view; E) left mandible, dorsal view; F) left mandible, ventral view. Scales: A, D: 0.5 m; B, C: 0.1 mm; E, F: 0.2 mm.

FIGURE 6. Mouthparts and right foreleg of Ora semibrunnea larva. A) Oval fields of sensory organs in the maxillary palpus segment 3; B) detail of sensory organs; C) maxillary palpus segment 4 apex detail; D) tibiotarsal organ of left foreleg, ventral view; E) right foreleg, dorsal view; F) hypopharynx; G) hypopharynx detail. Scales: A: 0.03 mm; B, C, D: 0.01 mm; E, F: 0.2 mm.

FIGURE 7. Abdominal tergites and sternites of Ora semibrunnea larva. A) Tergite VI; B) tergite VIII; C) tergite IX; D) sternite VIII; E) sternite IX. Scales: A: 0.5 mm; B, D, E: 0.2 mm; C: 0.1 mm.

FIGURE 8. Ora semibrunnea pupa. A) Habitus, dorsal view; B) habitus, ventral view; C) pronotal siphon, ventral view; D) left pronotal siphon, anterolateral view. Scales: A, B: 1 mm; C, D: 0.5 mm.

FIGURE 9. Ora semibrunnea pupa. A) Habitus, dorsal view; B) habitus, ventral view; C) female attachment organs; D) male attachment organs; E) detail of female attachment organs; F) detail of male attachment organs. Scales: A, B: 1 mm; C, D: 0.2 mm.

FIGURE 10. Ora semibrunnea larva and pupa. A) Pre-pupa, upside down; B) detail of pre-pupa breathing, tergite VIII, sternite IX, hydrophobic setae and spiracle apparatus; C) spiracle apparatus; D) with mature larvae exuviae under water; F) newly emerged adult on a macrophyte and exuviae of mature larva and pupa on the water surface. Scales: C: 0.2 mm; D: 1 mm.