Plecia Wiedemann

Sutou, Mitsuaki, 2006, Immature stages of three Japanese species of the genus Plecia Wiedemann (Diptera: Bibionidae), Zootaxa 1223, pp. 1-18 : 3

Genus Plecia Wiedemann

Diagnosis

Egg: Brown or fuscous in color, nearly lozenge shaped, broadest at middle ( Fig. 1 A).

Final­instar larva: Head capsule ( Figs. 1 G, 3G, 5D) shining, jet­black. Genae dorsaly with spotted stigmata being almost concolorous with cuticle. Frontal apotome anteriorly bordered with transverse chitinous band, and tapering posteriorly. Ecdysial suture forming undulating line, meeting each other posteriorly. Clypeus and labrum well developed, extending forward as fleshy protuberance; clypeus with conical projection laterally, its apex bare ( Figs. 1 H, 3H, 5E). Antenna reduced and modified to banana­shaped antennal plate behind clypeus. Eye spot observed as white spot on black head capsule. Mandible ( Figs. 1 I, J; 3I, J; 5F, G) stout, with 3–5 teeth. Maxilla ( Figs. 1 L, M; 3L, M; 5I, J) composed of 4 parts: cardo, galeolacinia, stipes, and maxillary palpus; proximal part of stipes isolated as small appendage. Labium ( Figs. 1 K, 3K, 5H) longer than wide with central membranous area, anterior and posterior margin concave; hypopharynx membranous, nearly elliptical in shape. Body ( Figs. 1 B, 3D, 5A), brownish or dark brownish, divided into 12 segments, each segment except prothoracic and 8th and 9th abdominal, subdivided into 3 subsegments. Each segment with transverse rows of processes ( Table 1 a), of these, lateral­dorsal ones on 8th and 9th abdominal segments longer than others. Prothoracic segment with plate­like ventral swelling having 2–5 blunt processes ( Figs. 1 C, 3E, 5B). Body cuticle covered with many spinules ( Figs. 1 D, 3F, 5C). Respiratory system holopneustic with 10 pairs of spiracles; anterior 9 pairs situated laterally on each segment, 10th pair situated dorsolaterally on intersegmental position between 8th and 9th abdominal segments; 1st pair of spiracles ( Fig. 1 E) on prothoracic segment about 2 times as large as 2nd to 9th pairs in diameter, while 10th pair ( Fig. 1 F) about 4 times as large as preceding pairs; all spiracles with 1 ecdysial scar (uniforous).

Pupa ( Figs. 2 , 4 , 6 ): Head and thorax dark brown. Vertex without median process. Sheaths of antennae, maxillary palpi, and rostrum distinct; width between antennal sheaths narrow. Sheaths of fore legs almost wholly visible, those of middle legs nearly so, whereas only extremities of those of hind legs visible, and remainder of them concealed under wing sheaths. Sheaths of halters partly concealed under wing sheaths. Abdomen brown, consisting of 9 segments, more or less tapered caudally; each segment bearing processes ( Table 1 b), of these, caudal ones stouter than others. Prothoracic spiracles and 6 pairs of spiracles on 2nd to 7th abdominal segments placed laterally; spiracles on 1st abdominal segment concealed under sheaths of halters on which wing sheaths lie.

Figures

FIGURE 1. Plecia adiastola. A, egg. B – M, final­instar larva. B, habitus, lateral view. C, plate­like ventral swelling of prothorax. D, spinules on dorsum of fourth abdominal segment. E, prothoracic spiracle. F, eighth abdominal spiracle. G, head, dorsal view. H, epipharynx. I, right mandible, dorsal view. J, right mandible, inner view. K, labium and hypopharynx, ventral view. L, left maxilla, dorsal view. M, left maxilla, ventral view. Abbreviations (full terms in parentheses): ant p (antennal plate), a st (appendage of stipes), cd (cardo), cly (clypeus), ec su (ecdysial suture), e st (eye spot), fr ap (frontal apotome), gala (galeolacinia), ge (gena), hyp (hypopharynx), lb (labium), lr (labrum), md (mandible), mxp (maxillary palpus), prs (prostheca), st (stipes). Scales: G, 0.5 mm. D – F and H – M, 0.1 mm.

FIGURE 2. Plecia adiastola, pupa. A, male, frontal view. B, male, lateral view. C, female, lateral view. Abbreviations (full terms in parentheses): ant (antenna), mxp (maxillary palpus), pro sp (prothoracic spiracle), rt (rostrum).

FIGURE 4. Plecia membranifera, pupa. A, male, frontal view. B, male, lateral view. C, female, lateral view. See Fig. 2 for abbreviations.

FIGURE 6. Plecia hadrosoma, pupa. A, male, frontal view. B, male, lateral view. C, female, lateral view. See Fig. 2 for abbreviations.