Apataniana stropones Malicky, 1993

Waringer, Johann & Malicky, Hans, 2016, The larvae of the European species of genus Apataniana Mosely, 1936 (Trichoptera, Apataniidae): descriptions, key and ecology, ZooKeys 586, pp. 121-134 : 123-125

Taxon classification Animalia Trichoptera Apataniidae

Apataniana stropones Malicky, 1993

Description of the 5th instar larva.

Diagnosis. Setae at anterior edge of pronotum long, tapering and with flexuous tips; setal transversal band at 1st abdominal dorsum continuous; 2nd tarsal claw shorter than half tarsal length; central submentum sides converging.

Biometry. Body length of 5th instar larvae ranging from 4.9 to 5.0 mm, head width from 0.73 to 0.74 mm (n= 3).

Head. Head capsule with dense cover of microspinules, roundish in shape and hypognathous (Figs 1-3). Coloration medium to dark brown; paler areas around eyes and around foramen occipitale (Figs 1, 2). Muscle attachment spots on frontoclypeus and parietalia small and indistinct (Figs 1, 2). In addition to complete set of primary setae, head capsule with many short, pale and almost translucent secondary setae (Fig. 2). Frontoclypeus bell-shaped, with narrow central constriction (Fig. 1). Antennae situated halfway between eye and anterior head margin (Fig. 1, arrow), short, each consisting of 1 short cylindrical base and 1 prominent lateral seta. Labrum dark brown, with setal brush at anterolateral corners originating from whitish pads of soft cuticle. Submentum wedge-shaped, sclerite almost as wide as long, convex-sided at center; light brown with medium brown pre-apical transverse band. Postgenal suture less than 20% of apotome length. Scraper-type mandibles (as in Fig. 15) black, brownish terminally, elongated quadrangular and without terminal teeth along cutting edge (as in Fig. 15).

Thorax. Pronotum medium brown, surface densely granulated, posterior margins thickened and darkly striped (Figs 4, 5). Pronotal transverse groove lacking, as typical for Apataniidae larvae (Figs 5, 6). In profile, pronotum slightly rounded (Fig. 5). Pronotal surface densely covered by pale, translucent, tapering setae with flexuous tips, especially along the anterior border (Fig. 6); in addition 30-40 longer setae present on each pronotal half (Figs 4, 5). As in other Apataniidae larvae, a defensive gland is situated beneath the pronotal sclerites. In all three European Apataniana larvae, an additional Y-shaped appendix is present which can be extended at the cervix between pronotum and head (=osmeterium; Fig. 5o); when threatened, the gland is able to produce a mix of up to 40 fatty acids as a defense agent against predacious invertebrates ( Wagner et al. 1990). Pentangular prosternite densely covered by microspinules, very pale and indistinct in its anterior and lateral sections; along posterior border with light brown transverse band; with distinct, light brown and triangular lateral sclerites. Prosternal horn present. Mesonotum completely covered by 2 light brown sclerites; their anterior, lateral and postero-lateral margins darker sclerotized; mesonotal surface with medium brown muscle attachment spots (Fig. 4). Metanotum partially covered by only 1 pair of yellowish lateral sclerites with anterior groups of approximately 20 setae per sclerite and dark brown muscle attachment spots; anterior and posterior metanotal sclerites completely lacking and replaced by groups of setae: 15-20 at each anterior and 15-18 at each posterior metanotal position (Fig. 7). Legs yellowish to light brown with numerous setae on coxae, trochanters and femora; tibiae and tarsi with only a small number of setae (Figs 8-10). Femora each with more than 1 proximodorsal seta. Coxa, femur and tibia of each foreleg wider than those of mid- and hind legs. Additional se tae present at anterior and posterior faces of all femora. Setae lacking at distal sections of trochanter on all legs. Mid tarsal claw shorter than half tarsal length; in addition, tarsal claw seta long and almost reaching tip of tarsal claw (Fig. 12).

Abdomen. 1st abdominal segment with 1 dorsal and 2 lateral fleshy protuberances densely covered by microspinules. Setal transversal band at 1st abdominal dorsum continuous at center, consisting of 45-60 setae (Fig. 7); dorsal of each lateral protuberance, an additional group of 7-10 setae is present. Ventral section of lateral protuberances and 1st abdominal sternum with continuous field of setae with basal sclerites minute and inconspicuous; total setal number is 130-150.

8th abdominal dorsum with 14-18 posterodorsal setae; several posterolateral setae on each half of 9th abdominal dorsum. All gills single filaments. Dorsal gills present at most from 2nd segment (postsegmental position) to 4th segment (postsegmental position). Ventral gills ranging from 2nd (postsegmental) to 6th segment (postsegmental). Lateral gills lacking. Lateral fringe extending from start of 2nd to mid 8th abdominal segment. Dorsal of lateral fringe a small number of forked lamellae is present per segment (as in Figs 20, 21).

Light brown sclerite on 9th abdominal segment semicircular, with light muscle attachment spots; with 26-33 setae, 6 long and the remainder short to medium in length (Fig. 14). Anal prolegs of the limnephilid type, light brown and with dark brown bar at anterodorsal border of claw base. Anal proleg lateral sclerite with 5 setae along posterior edge (Fig. 13). Anal claws dark brown, with tiny dorsal accessory hook.

Case. Fifth instar larval case 5.4-5.5 mm long (n= 3), curved, tapering posteriorly (width at anterior opening 1.8-2.0 mm and at posterior opening 0.9-1.1 mm), consisting of mineral particles of varying size, sometimes mixed with larger particles attached mostly laterally, thereby creating wing-like structures (Fig. 11).