Rhyacophila gudrunae Malicky 1972

Waringer, Johann, Karaouzas, Ioannis & Malicky, Hans, 2018, The larvae of Rhyacophila tsurakiana Malicky 1984, Rhyacophila gudrunae Malicky 1972, and Rhyacophila biegelmeieri Malicky 1984, including an update for the larval key to the Greek species of genus Rhyacophila Stephens 1836 (Rhyacophilidae, Trichoptera), Zootaxa 4508 (1), pp. 85-100 : 86-87

Description of the final instar larva of Rhyacophila gudrunae Malicky 1972

Biometry. Body length ranging from 20.0 to 21.7 mm, head width from 1.17 to 1.26 mm (n = 3). Chaetotaxonomy according to Williams & Wiggins (1981) and Friedrich et al. (2015), anal proleg terminology following Nielsen (1942).

Head. Head capsule finely wrinkled, rectangular, with lateral margins almost parallel, slightly convergent anteriorly, posterior third evenly rounded ( Figs 1–2 ). Coloration pale yellowish, with conspicuous dark brown, oval muscle attachment spots at dorsal, ventral, and lateral sides of parietalia, at frontoclypeus, and along coronal suture ( Figs 1–2, 5 ). In addition, with median brown pigmented areas (1) at posterior third of frontoclypeus, including 3– 4 light muscle attachment spots; (2) on parietalia, dorsally from posterior frontoclypeal suture beside posterior coronal suture to foramen occipitale ( Fig. 1 ); (3) laterally, at eye level, from seta #12 to apophysis of foramen occipitale ( Fig. 5 ), and (4) ventrally, from foramen occipitale to center of parietalia ( Fig. 2 ). With brownish-yellow anterior margin of frontoclypeus and pale brown patches immediately posterior of frontoclypeal margin and around setae #5 ( Fig. 1 ). On each parietal, 13 dorsal and 5 ventral primary setae present, with setae #9, 12, 14 and 15 long and conspicuous ( Fig. 1 ). In addition, 17 pairs and a single sensory pit (sensilla campaniformia) present, 3 pairs and the single pit situated on frontocylpeus. Frontoclypeus bell-shaped, with deep central constriction and 5 pairs of primary setae, 2 of them near anterior border (#2–3) ( Fig. 1 ). Antennae each midway between anterior border of eye and lateral base of mandible, antennal base conical, antenna short, with short flagellum. Labrum pale yellow, with 6 pairs of primary setae (only 3 pairs visible in Fig. 1 ). Ventral apotome triangular, with thickened anterior border ( Fig. 2 ). Mandibles medium brown, almost black apically, and asymmetrical ( Fig. 3 ): right mandible with short, stout basal tooth, lacking on left mandible and replaced there by straight cutting edge. Each mandible base with 2 setae laterally ( Fig. 3 , arrows).

Thorax. Pronotum fully covered by 2 large sclerites, tapering posteriorly. Pronotal sclerites yellowish, each with reddish brown muscle attachment spots creating arc–like pattern marked also by light brown pigmentation pointing toward anterolateral corner. In addition, circles of muscle attachment spots situated on posterolateral halves of sclerites, each with seta #5 on anterior border of circle. Dark round spot anterolateral of each seta #5; further muscles attachment spots and narrow stripes of pigment bordering posterior half of median suture ( Figs. 4a, 5 ). Posterior pronotal corners prolonged ventrally ( Fig. 5 ). Posterior and lateral margins thickened and darkly striped, including anterolateral corners; posterior dark border interrupted by pale patch dorsal of posterior bulge; lateral borders straight to slightly concave. Pronotal notch at anterolateral corner large, deep and semicircular, with 2 long setae ( Fig. 4a , #22, #23) and 3 tiny ( Fig. 4a , dotted oval). Prosternal horn lacking, prosternite narrowly quadrangular, with four medium-brown patches ( Fig. 4b ). Meso- and metathoraces totally unsclerotized, white, with pale purplish-blue coloured areas subdivided by whitish bands; each with single pair of anterior sa 1 setae and groups of one long and two tiny posterior sa 2 setae. Foretrochantins large, each with dark central stripe and large rounded anterior process bearing terminal seta #10 ( Figs 4a, 5 , 6 ). Pleura of meso- and metathoraces each with upright, single-filament gill; episterna and epimera elongate, black ( Figs 7–9 ). Legs pale brown, with borders of sclerites darker and with numerous setae on coxae, trochanters, and femora; tibiae and tarsi with only small number of setae ( Figs 6–8 ). Forefemora distinctly wider than mid- and hind femora. Tarsal claws long and slender, curved, pointed, with basal spur originating from conical base ( Figs. 6–8 ).

Abdomen. Abdomen slightly depressed (flattened dorsoventrally); dorsally pale purplish–blue, with coloured areas subdivided by pale bands. Laterally and ventrally pale cream coloured. Each segment with 2 pairs of long dorsal primary setae ( Fig. 10 , setae #2, 5), a pair of lateral gills consisting of four filaments, originating from short, truncate base ( Fig. 10 ), and pair of ventral setae ( Fig. 11 , #10). Lateral fringe lacking. Abdominal dorsum IX with large, yellow quadrangular sclerite with black anterior and posterior borders ( Fig. 12 ); anterior border slightly narrower than posterior border, with outermost setae inserted on lateral borders of this sclerite ( Fig. 12 ). Anal prolegs each consisting of proximal sclerite ’b’ with long sword process and ventral basal hook ( Fig. 11 bp, h, sp), pointed distal sclerite ‘b’, ventral ‘c’ sclerite ( Fig. 11 bd, c), and long, curved anal claw (ac) partially divided by ventral membranous section fitted with two tiny ventral teeth ( Fig. 11 , arrow).

Figures

FIGURES 1–5. Rhyacophila gudrunae Malicky 1972, 5th instar larva. 1, head, dorsal (lb = labrum; small numbers refer to setal positions); 2, head, ventral (small numbers refer to setal positions); 3, mandibles, ventral (maxillolabium removed; arrows= lateral setae); 4a, prothorax, dorsal (small numbers refer to setal positions; dotted oval= tiny setae of pronotal notch); 4b, prosternum (p= prosternite); 5, head and prothorax, right lateral. Scale bars: 0.5 mm.

FIGURES 6–10. Rhyacophila gudrunae Malicky 1972, 5th instar larva. 6, left foreleg, anterior (small numbers refer to setal positions); 7, left mesothoracic gill and midleg, anterior; 8, left metathoracic gill and hind leg, anterior; 9, detail of right mesothoracic gill, right lateral; 10, gills of abdominal segment VII, anterolateral (small numbers refer to setal positions). Scale bars: 0.5 mm.

FIGURES 11–15. Figures 11–12. Rhyacophila gudrunae Malicky 1972, 5th instar larva. 11, abdominal segments IX, X and anal proleg, right lateral (ac = anal claw; bd = distal ‘b’ sclerite; bp = proximal ‘b’ sclerite; bv = ventral ‘b’ sclerite; c = ‘c’ sclerite; h = proximal hook of sclerite ‘b’; small numbers refer to setal positions; arrow = teeth on anal claw); 12, abdominal segments IX, X and anal proleg, dorsal. Figures 13–15. Rhyacophila tsurakiana Malicky 1984, 5th instar larva. 13, head, dorsal; 14, head, ventral; 15, prothorax, right lateral. Scale bars: 0.5 mm.