Limnephilus barbagaensis, Malicky, Sekhi & Lounaci, 2019

Karaouzas, Ioannis & Dambri, Besma, 2022, Larval description of Limnephilus barbagaensis Malicky, Sekhi & Lounaci 2019 (Trichoptera: Limnephilidae), a micro-endemic of Algeria, with notes on its ecology, Zootaxa 5162 (2), pp. 163-172 : 164-165

Description of the fifth instar larva of Limnephilus barbagaensis

( Figs 3–16 )

Biometry. Body length of 5th instar larva 13–17 mm, head width 1.32–1.44 mm (n = 4).

Head. Head capsule oval, hypognathous, granulate. Head uniformly dark brown, lighter in the posterior area of the coronal suture and at the constriction of the frontoclypeus ( Figs 3, 4 ). Numerous dark brown, conspicuous muscle attachment spots arranged transversely in lateral view; in dorsal view, spots arranged in transversal line on both sides of head reaching parietalia ( Figs 3, 4 ). Rings surrounding muscle attachment spots darker than ground colour; central parts of rings lighter and same colour as ground colour. Pale ring present around each eye ( Figs 4, 5 ). Frontoclypeus bell-shaped, with deep constriction at midlength; numerous (approx. 12) light and visible attachment muscle spots forming triangular pattern in posterior third of frontoclypeus ( Fig. 3 ). Antennal bases cylindrical, nearly round, situated halfway between eye and anterior head margin. Antennae short, each consisting of one short cylindrical base and one short flagellum ( Fig. 5 , white arrow). Labrum same color as head background; cardines light brown ( Fig. 6 , white arrow). Ventral apotome amphora-shaped, light –yellowish brown, with wedge-shaped reddish brown anterior border ( Fig. 6 va). Mandibles black, each with four teeth along its terminal edge ( Fig. 5 , red arrow) and with ridges in central concavity.

Thorax. Pronotum dark brown, its surface finely granulated, with dark, oval muscle attachment spots; dark, shallow, transverse groove at anterior 1/3 ( Fig. 7 , black arrow); and posterior border bent dorsad, thereby creating black, transverse, semicircular groove ( Fig. 7 , red arrow); total of 44–56 dark setae of varying lengths distributed across both pronotal halves. Prosternal horn present, short ( Fig. 8 ph); light brown central prosternite conspicuous, broadly trapezoidal ( Fig. 8 cp); lateral prosternites conspicuous, separated from central prosternite, and with dark brown marks ( Fig. 8 lp). Mesonotum dark brown, but lighter than pronotum, completely covered by pair of sclerites meeting in straight mid-dorsal ecdysial line ( Fig. 9 ); darker brown muscle attachment spots visible, especially at midline and anterolateral margins ( Fig. 9 ); posterolateral and posteromedian margins strongly sclerotized and black ( Fig. 9 ); pairs of mesonotal setal groups and corresponding sclerites are as follows (nomenclature sensu Wiggins 1996): anterior submesal sclerites and seta ( sa 1) 5–7, posterior group ( sa 2) 7–10, lateral setal group ( sa 3) 15–17. Metanotum yellowish, mostly membranous with 3 pairs of brown sclerites ( Fig. 9 ); anterior median sclerites ( sa 1 sclerites) brown and ovoid with 4–6 setae per sclerite ( Fig. 9 sa 1). Posterior median sclerites ( sa 2 sclerites) brown, rectangular or trapezoidal, with 5–7 setae per sclerite ( Fig. 9 sa 2). Lateral sclerites ( sa 3 sclerites) light yellowish brown, crescent-shaped, each with 13–15 setae concentrated at anterior third of sclerite ( Fig. 9 sa 3).

Legs. Yellowish, with numerous setae on coxae, trochanters and femora; tibiae and tarsi with small number of setae ( Figs. 14–16 ). Femora of all legs each with row of short spines along ventral edge; femora of mid- and hindlegs each with one proximodorsal seta and 4–5 subapicodorsal setae, 2 dark primary ventral setae (vs) at mid-length ( Figs 14–16 ); additional face setae lacking on anterior and posterior faces of mid- and hind femora ( Figs 15a, 15b, 16a, 16b ). Femora of forelegs shorter and thicker than those of mid- and hind legs ( Figs 14–16 ). Tibiae and tarsi of forelegs shorter than those of mid- and hind legs ( Figs 14–16 ). Tibiae of all legs each with 2 pale, subapicoventral spurs, tarsi each with 2 long subapical setae (one dorsal, one ventral); tarsal claws long, slender, curved, each with stout basal spine ( Figs 14–16 ).

Abdomen. Abdominal segment I unsclerotized, white, with 1 dorsal and 2 lateral fleshy spacing humps. Dorsal sa 1, sa 2, and sa 3 ( sensu Wiggins 1996) with 5–9 setae each. Lateral spacing humps lacking posterior sclerites and each with single ventral seta ( Fig. 10 lp). Setae lacking posterior to dorsal spacing hump. Abdominal sternum I with 5–7 setae in each sa 1, 9–12 setae in each sa 2, and 5–6 setae in each sa 3, situated ventral of lateral spacing humps ( Fig. 10 ). Gills present on abdominal segments II–VII; anterior gills each consisting of three filaments, decreasing to one or two filaments on posterior segments; dorsal and lateral gills present at most on abdominal segments II to V; ventral gills on segments II to VII. Lateral fringe extending from anterior border of abdominal segment III ( Fig. 10 lf) to end of abdominal segment VIII. Number of posterodorsal setae on abdominal tergite VIII 10–12, with three pairs long and others short ( Fig. 11 pds). Chloride epithelium, if present, not visible in our alcohol-preserved specimens. Abdominal segment IX with 1 pair of posterolateral setae ( Fig. 11 pls) and two pairs of ventral setae ( Fig. 12 , dotted circle); tergite IX semicircular, yellowish brown, with darker muscle attachment spots mostly near anterior edge ( Fig. 11 ), its posterior border with two pairs of long, prominent setae and three pairs of shorter setae, and one unpaired shorter seta positioned on midline ( Fig. 11 , red arrow). Anal prolegs of limnephilid type, yellowish brown, with several dark brown muscle attachment spots ( Figs 11, 12 ); lateral sclerites (ls) each with seven or eight dark dorsal setae and row of five dark ventral setae, four of latter very strong and prominent ( Figs 11, 12 ); basal sclerites yellow; anal claws dark brown, each with 1 small dorsal accessory hook ( Fig. 12 ac).

Case. Larval case 18–21 mm long (n = 3), nearly straight, slightly tapering posteriorly, consisting of small rock fragments and gastropod shells, with or without living gastropods ( Fig. 13 ).

Figures

FIGURES 3–8. Limnephilus barbagaensis Malicky, Sekhi & Lounaci 2019, 5th instar larva. 3, head and frontoclypeal apotome, frontal. 4, head, dorsal, scale bar: 0.5 mm. 5, antennal base and antenna (white arrow), mandible and mandibular teeth (red arrow). 6, head, ventral (white arrow = cardo; va = ventral apotome), scale bar: 0.5 mm. 7, head and pronotum, lateral view (black arrow = transverse rim; red arrow = semicircular groove). 8, thorax, ventral (ph = prosternal horn; cp = central prosternite; lp = lateral prosternite).

FIGURES 9–13. Limnephilus barbagaensis Malicky, Sekhi & Lounaci 2019. 9, pro-, meso-, and metanota (sa1–sa3 = setal areas 1–3, with sclerites and setae). 10, abdominal segments I–IV, right ventrolateral (dotted circles refer to sa1–3 = setal areas 1–3 on abdominal segment I; lp = lateral protuberance; lf = lateral fringe). 11, abdominal segments VIII–X, dorsal (pds = posterodorsal setae on abdominal tergum VIII; pls = posterolateral seta [paired] of abdominal segment IX; red arrow = unpaired seta on midline of tergite IX, ls = lateral sclerite of anal proleg [paired]). 12, abdominal segments VIII–X, ventral (dotted circle = ventral setae on abdominal sternum IX [paired]; ac = anal claw [paired]). 13, larval case, right lateral.

FIGURES 14–16. Limnephilus barbagaensis Malicky, Sekhi & Lounaci 2019. 14, left and right forelegs: 14a, anterior faces; 14b, posterior faces. 15, left and right midlegs: 15a, anterior faces; 15b, posterior faces. 16, left and right hind legs: 16a, anterior faces; 16b, posterior faces.