Description of the final instar larva of Apatania cypria Tjeder 1952

Biometry. Body length ranging from 6.4 to 6.7 mm, head Width from 0.66 to 0.74 mm (n = 2).

Head. Head capsule roundish, densely covered by microspinules (Figs 1–2). Coloration medium to dark broWn With pale yelloWish areas around eyes, around occipital foramen, and on posterior and ventral sections of parietalia (Figs 2, 4). YelloWish muscle attachment spots Within dark broWn areas small, roundish, and Well defined posterodorsally (Fig. 4). In addition to complete set of primary setae, head capsule With many short, pale and almost translucent secondary setae (Fig. 3, ss). Setal ratio (= median separation 'a' of pair of frontoclypeal setae #5 divided by distance 'b' to next frontoclypeal border; Fig. 1)> 8. Seta #15 barely half as long as seta # 14 (Fig. 1). Frontoclypeus bell-shaped, greatly increasing in Width anterior of narroW central constriction (Fig. 1). Antennae situated halfWay betWeen eyes and anterior head margin (Fig. 1, arroW), short, each consisting of 1 short conical base and 1 prominent lateral seta. Labrum dark broWn, With setal brush at anterolateral corners. Submentum light broWn, Wedge-shaped, With Wide, heavily sclerotiZed, dark broWn anterior section; anterior margin semicircular (Fig. 2, s). Cardines black, narroW, elongated, With short antero-ventral projections. Postgenal suture approximately 24% of apotome length. Scraper-type mandibles black, broWnish terminally, elongate-quadrangular and Without terminal teeth along cutting edges (Fig. 2, arroW).

Thorax. Pronotum yelloWish broWn, posterior margins thickened and darkly striped (Fig. 4). Without pronotal transverse groove (Fig. 4, arroW). In profile, pronotum slightly rounded (Fig. 4). Pronotal surface finely granulated and densely covered by pale, translucent, tapering setae With flexible tips, especially along anterior border (Fig. 3, as); in addition 50–60 longer setae present on each pronotal half (Figs 3, 4). As in other Apataniidae larvae, defensive gland situated beneath pronotal sclerites; its sac-like reservoir frequently extended during preservation (Fig. 4, o). Prosternite densely covered by indistinct microspinules; With prosternal horn (Fig. 2, ph). Mesonotum completely covered by 2 light broWn sclerites divided by straight, narroW, longitudinal suture Widening posteriorly (Fig. 5, arroW); anterior and postero-lateral margins heavily sclerotiZed. Mesonotal surface With medium broWn muscle attachment spots and covered With 55–67 setae per sclerite (Fig. 5, ms). Metanotum partially covered by only 1 pair of pale-yelloWish lateral sclerites fitted With dark broWn posteroventral corners (Fig. 9, sa 3); anterior groups of approximately 15–17 setae per sclerite. Anterior and posterior metanotal sclerites completely lacking and replaced by groups of setae: 10–13 at each anterior (Fig. 5, sa 1) and 8–12 at each posterior metanotal position (Fig. 5, sa 2). Legs yelloWish to light broWn With numerous setae on coxae, trochanters, and femora; tibiae and tarsi With only small number of setae (Figs 6–8). Femora each With 1 or more proximodorsal setae (Fig. 8, arroW). Forelegs short and stout, each With coxa, femur, and tibia Wider than those of mid- and hind legs (Fig. 6). Additional setae present at anterior and posterior faces of all femora. Setae lacking at distal sections of trochanters on all legs. Major femoral setae and tibial spurs pale. Tarsal claWs strongly curved, each fitted With basal seta originating from a socket, this seta long and almost reaching tip of tarsal claW.

Abdomen. Abdominal segment I With 1 dorsal and 2 lateral fleshy protuberances (Figs 5, 9; dp, lp). In dorsal midline, setal areas sa 1 distinctly separated by gap created by dorsal protuberance (Fig. 5, dotted oval). At height of metathoracic lateral sclerite sa 3, setae lacking on pleura of abdominal segment I betWeen dorsal setal group sa 1 and setae associated With lateral protuberance (Fig. 9, dotted oval). On abdominal sternum I, setal areas sa 1 and sa 2 fused, creating continuous field of setae With tiny basal sclerites; combined setal number 33–37. Sternal setal areas sa 3 each With 10–12 setae (Fig. 10).

Abdominal dorsum VIII With 2 long and 10 short posterodorsal setae (Fig. 13, ds). All gills single filaments (Fig. 9). Dorsal gills present at most from segment II (presegmental position) to segment IV (postsegmental position). Ventral gills ranging from segment II (postsegmental) to segment VI (postsegmental). Lateral gills lacking. Lateral fringe extending from anterior border of segment II (Fig. 9, arroW) to end of segment VII (Figs. 11, 12, lf). From 0 to 2 forked lamellae (Figs. 11, 12, dotted ovals) present dorsally of lateral fringe (Figs. 11, 12, lf) on abdominal segments III to VII.

Tergite of abdominal segment IX trapeZoidal, yelloWish broWn, With 28–32 setae, central setae and outermost setae conspicuously enlarged (Fig. 13), With one to several posterolateral setae (Fig. 13, arroW). Anal prolegs of limnephilid type, light broWn, With black bar at anterodorsal border of ventral sole plate. Anal proleg lateral sclerite With 5 setae along posterior edge With setae #2 and 3 long and prominent (Fig. 12, ls). Anal claWs dark broWn, each With 2 tiny setae and Without accessory hook (Fig. 12, c).

Case. Fifth instar larval case 6.3_7.9 mm long (n = 2), curved (Fig. 14), slightly tapering posteriorly (Width at anterior opening 2.2–2.3 mm and at posterior opening 1.4–1.5 mm), consisting of mineral particles of varying siZe. Dorsal section of anterior opening protruding (Fig. 14).