Brachyopa panzeri, Goffe, 1945

Shparyk, V. Yu. & Zamoroka, A. M., 2021, Description Of The Puparium And Redescription Of The Third-Instar Larva Of Brachyopa Panzeri (Diptera, Syrphidae) With New Data On Its Biology, Zoodiversity 55 (3), pp. 207-216 : 209-212

Third larval instar of Brachyopa panzeri

O v e r a l l c h a r a c t e r s. Brown to pale in colour, brown-grey dorsally, pale ventrally, basal plate dark. Length 7.3 ± 0.7 mm, width 3.1 ± 0.2 mm (n = 8). Body dorsoventrally flattened, rounded anteriorly and tapered posteriorly, with well sclerotized breathing tube. Dorsal and lateral surface covered by sclerotized setae and spicules ( fig. 1 ). Lateral surface of metathorax and abdominal segments with two sensilla, which increase in size in abdominal segments 5–7 and anal segment. The ventral surface vestiture consisting of pale spicules not forming contrasting transverse rows. Ventral part of II–VI abdominal segments (A2–A6) with dark dot-like contrasting areas at the center ( fig. 1 ). Prothorax (P) and mesothorax (Ms) with 6 pairs of sensilla; metathorax (Mt) with 6 pairs of sensilla. Abdominal segments A1–A7 with seven pairs of sensilla, anal segment (A 8) with three pairs of sensilla and four pairs of lappets ( fig. 2 ).

H e a d a n d t h o r a x. Mouth-hooks and mandibular lobes internal. Ventral lip forming a well-developed black lunula, contrasting against the background. Lateral lips rounded and covered ventrally by a dense tuft of long thin setae, which are short and thick dorsally and very close together over the dorsal lip. Dorsal lip not clearly visible. Antenno-maxillary organs well developed, located between mouth and dorsal surface of the prothorax. Dorsal surface of prothorax covered by hook-shaped spicules with a sclerotized black tip and a fleshy pale-coloured basal part. The spicules directed radially from the mouth opening. The second pair of sensilla situated near anterior spiracles on the lateral margin of prothorax. Spiracles cylindrical, about 2.5 times longer than wide.

The prothorax and mesothorax dorsally form a wide plate with multiple sensilla without fleshy papillae. The prothorax dorsally with two transverse rows (anterior and posterior) of sensilla without visible fleshy papillae. The anterior row consists of 2 pairs of sensilla with short setae, approximately the same size. This row of sensilla sits frontward of the anterior respiratory spiracles. The posterior row includes 1 pair of sensilla with 2 long and 2–5 short setae. The lateral sensillum of prothorax (PL 4) sits on a small fleshy papilla ( fig. 2 ). Mesothorax with 2 pairs of dorsal sensilla (MsD 1, MsD 2). Metathorax with 4 pairs of dorsal (MtD 1, MtD 2, MtD 3, MtD 4) and 2 pairs of lateral (MtL 5, MtL 6) sensilla. The area between the sensilla of the pro- and mesothorax covered by blotches darker than the base colour. The border between prothorax and mesothorax is only clearly visible laterally and ventrally. The surface apically and laterally from the sensilla is covered with hook-shaped spicules. Ventral side of pro-, meso- and metathorax without sensilla ( fig. 2 ).

Abdomen. Dorsal part of abdominal segments A1–A6 with 4 pairs of sensilla (A1D 1 –A1D 4 to A6D 1 –A6D 4). Segments A1–A6 dorsally with a distinct transverse groove. The metathoracic an abdominal sensilla D 1 –D 4 sit on the anterior margin of Mt, A1–A6. Larval discs (w), which serve to allow protrusion of the anterior pupal spiracles, are situated between A1D 1 and A1D 2 ( fig. 2 ). Abdominal segments A2-A6 with non-functioning spiracles between D 1 and D 2. Segments A1–A6 posteriorly with 2 transverse rows of black spicules. Dorsal integument in polygonal brown blotches, with clearly visible rows of dark setae. Sensilla A1D 1-4 –A6D 1-4 with 2–3 long and 3– 5 short setae and a small papilla. Sensilla A7D 3, A7D 4 with 2–6 thick lateral setae and a well-developed long papilla.

Sensilla A1L 5-6 –A7L 5-6 with well-developed basal papilla. Papilla of sensillum L 6 1.5– 2 times longer than sensillum L 5. Sensilla A5L 6 –A7L 6 5–7 large with 6–9 lateral setae (resemble lappets on the anal segment), directed to the posterior margin of the larvae ( fig. 1 ).

The ventral surface of abdominal segments A1–A7 segments bearing 1 pair of sensilla with two apical long setae ( fig. 2 ). Setae bicoloured, with pale base and black apex. Segments A1–A6 ventrally with a distinct transverse groove and black central blotch. Sensilla A7D 3 and A7D 4 with long, fleshy basal papillae (similar to A8L 1, A8L 2, A8L 3).

Anal segment (A8) about 1.5 times longer than A7, divided in anterior and posterior parts. Anterior part with 2 pairs of long lateral lappets A8L 1, A8L 2, bearing 8–12 lateral and 7–9 apical setae which vary in size. Posterior part bearing 1 pair of lappets A8L 3 with 9– 16 apical setae of different size. The lateral surface of A8 with 3 pairs of simple sensilla (A8V 4, A8V 5, A8V 7) and 1 pair of anal lappets (A8V 6).

Posterior breathing tube long, at least 6 times as long as wide, dull on the base and lustrous on the apex. A spiracular plate sitting on the apex of breathing tube, with distinct morphological structures ( fig. 3 ) including two central round scars, four pairs of spiracular openings and six pairs of branched inter-spiracular setae. First dorsal pair of spiracular openings C-shaped and approximately 40 μm long; second straight and short (10 μm); lateral third pair slightly S-shaped, and about 35 μm long. Ventral fourth spiracular openings straight, 30–35 μm long ( fig. 3 ).

Puparium of Brachyopa panzeri

O v e r a l l d e s c r i p t i o n. Puparium elongated-ovate, flattened dorsoventrally, expanded anteriorly and narrowed posteriorly. Cuticle dull, reddish to dark brown, covered with dried remnants of fleshy projections bearing setae. Setae dark coloured, the same length as in the larvae. Posterior breathing tube sclerotized, dull and dark coloured at the base, lustrous and light brown on the apex, translucent ( fig. 4 ). Length including prp: 5.1 ± 0.8 mm; width: 3.1 ± 0.3 mm; height: 2.5 ± 0.3 mm (n = 8).

P u p a l s p i r a c l e s. Anterior pupal spiracles ( fig. 4 , A: arp) cylindrical (0.62 ± 0.02 mm long, 0.19 ± 0.03 mm wide, n = 8), slightly narrowed toward apex and slightly curved backward. Cuticle dull, reddish to light brown, densely tuberculate. Distinct tubercles 3–6 μm in diameter, arranged in subspiral rows ( fig. 4 , B). Large tubercles arranged in subradial longitudinal rows of 4–7 pieces. Spiracular openings slit-like, 3–7 grouped radially (sometime chaotically) on the apex of large tubercles ( fig. 4 , C). These slit-likes openings are located on oval prominences, which are longitudinally divided into two parts by slits ( fig. 4 , D: SO). Both spirals are based on the middle of the upper part of the operculum, separated by a distance of approximately the length of the spiracle.

Figures

Fig. 1. The dorsal (A) and ventral (B) views of third-instar larva of Brachyopa panzeri. Labels: P — prothorax, Ms — mesothorax, Mt — metathorax, A1, A7, A8 segments of the body (segments A2–6 similar to A1); cd — central dark area, V7 — ventral sensillum of second abdominal segment; prp — posterior breathing tube; lp — lappets, am — atenno-maxillary organ; vl — ventral lip; w — larval discs.

Fig. 2. Chaetotaxy map of the third instar larva of B. panzeri showing position and numbering of segmental sensillum (lateral view). Labels: D — dorsal, L — lateral, V — ventral projections; P — rothorax, Ms — mesothorax, Mt — etathorax, A1–A8 — abdominal segments (A3–A6 not shown); prp — posterior breathing tube; Sp — anterior spiracle; W — larval disc; Lp — lappets, m — mouth, a — anal opening.

Fig. 3. Scanning electron microphotograph of larval spiracular plate on the apex of breathing tube of Brachyopa panzeri (SEM). Labels: CS — central scars; IS — interspiracular branched setae; SP — spiracular opening.

Fig.4. Morphology of Brachyopa panzeri puparium.A — opened pupa in dorsal view; B — upal spiracle, lateral view; C — pupal spiracle, apical view; D — spiracular openings of pupal spiracles (SO).