Tipula (Pterelachisus) irrorata Macquart, 1826

Podeniene, Virginija, Nasevičiene, Nijole & Podenas, Sigitas, 2019, Notes on the first instar larvae of the genus Tipula (Diptera: Tipulidae), Zootaxa 4567 (1), pp. 90-110 : 99-100

Tipula (Pterelachisus) irrorata Macquart

( Figs. 31–39 )

Examined material: 3 egg-larvae from female captured in Vilnius, N54.68194, E25.27087, 17-VI-2011, eggs were laid on 19 VI 2011, egg-larvae hatched on 4 - VII-2011.

First instar larva. Length 1.99–2.02 mm, width 0.42–0.43 mm. Body covered with pale microscopic hairs. Cuticle transparent.

Head capsule. Length 0.41–0.42 mm, width 0.25–0.27 mm. In general, very similar to that of T. (L.) vernalis . Differences were noticed in shape of hypostomium, mandible, antenna and arrangement of sensory structures on labrum. Hypostomium bears five sharp long teeth and shape of teeth differ from that of T. (L.) vernalis and other above mentioned species ( Fig. 31 ). Mandible generally very similar to that of T. (L.) vernalis and other above mentioned species, but shape of teeth slightly different ( Fig. 32 ). Shape of segment of antenna and size of apical papilla differ from that of T. (L.) vernalis and other above mentioned species ( Fig. 33 ). Labrum in general very similar to that of other known Tipula , but arrangement of setae differs from other above mentioned species ( Fig. 34 ): two medium long and one very short setae present on membranous part on both sides of labrum. One medium long and three very short setae located on anterior part of labrum; one long and two short setae present on anteriolateral part of labral lobe; one long and one very short setae located on posterior part of labral lobe. Arrangement of setae on frontoclypeus is slightly different than in other species ( Fig. 35 ).

Thorax. Very similar to that of other known Tipula .

Abdomen. In general very similar to that of other known Tipula . Seta D4 the shortest. D3 the longest among all setae, it is nearly three times as long as D4 ( Fig. 36 ). D2, D5 and D6 very similar in length and nearly twice as long as D4. D2 and D3 very close to each other. V1 present ( Fig. 37 ). V1, V2, V4 and V5 are short and similar in length. V3 almost twice as long as other ventral setae. V1–V2 and V4–V5 make pairs and are very close to each other. L3 very short, L2 twice as long as L3. L2 and L4 very similar in length and five times as long as L3. L2 and L3 very close to each other, when other setae are equidistant ( Fig. 38 ).

Spiracular disc. Spiracular field surrounded by four almost equal round-tipped lobes, which are flat and elongate ( Fig. 39 ). Lateral lobe as long as wide at the base, partly (inner part) covered with dark elongated Lshaped sclerite, lower branch of sclerite extends almost to the center of spiracular field. Lobe bears four stout apical bristles. Each bristle slightly more than three times as long as the lobe. Length of ventral lobe almost as width at the base, apical part of lobe covered with pale sclerite. Two long setae located on the apical part of ventral lobe, outer and inner margins bear one short seta. Five tufts of two setae present on outer margin of spiracular field. Three tufts of medium long setae located directly above spiracle. Laterally from them two tufts of very short setae. Five tufts of two shorter and medium long setae located above the each spiracle. Three the innermost tufts are close to each other and consist of two medium long setae each. Laterally from it are two tufts of two short setae, which are also close to each other. Spiracles large, circular and close to each other. Distance between them less than diameter of a spiracle.

Anal field. Anus surrounded by four short, white and fleshy anal papillae. A few long setae present on anal segment.

Figures

FIGURES 31–39. Tipula (Pterelachisus) irrorata, first instar larva. 31: hypostomium; 32: right mandible; 33: right antenna; 34: general view of labrum; 35: frontoclypeal setae; 36: dorsal abdominal setae (segments II–VII); 37: ventral abdominal setae (segments II–VII); 38: lateral abdominal setae (segments II–VII); 39: spiracular field.