Rhyacophila fasciata Hagen 1859

Valladolid, María, Arauzo, Mercedes, Chertoprud, Mikhail V., Chvojka, Pavel, Czachorowski, Stanisław, Dorda, Beatriz A., Hinić, Jelena, Ibrahimi, Halil, Karaouzas, Ioannis, Krpač, Vladimir, Kučinić, Mladen, Lodovici, Omar, Salokannel, Juha, Stamenković, Valentina Slavevska & Stojanović, Katarina, 2021, The Rhyacophila fasciata Group in Europe: Rhyacophila fasciata Hagen 1859 and formerly synonymized species (Trichoptera: Rhyacophilidae), with new description of Rhyacophila fasciata and Rhyacophila septentrionis McLachlan 1865 (stat. prom.)., Zootaxa 4975 (1), pp. 1-57 : 17-23

Rhyacophila fasciata Hagen 1859

Description of the larva ( Figs 4–9 , 21 ).

The description of the specimens examined will be complemented with descriptions of previous authors, adding or confirming features.

Biometrics of last instar larva and prepupa: Length: 14.25–19.00 mm ( = 16.09, n = 13). Maximum width: 2.98–3.90 mm ( = 3.28, n = 13) ( Lepneva 1964, 5 th instar larval length: 23.00– 23.40 mm; Nielsen 1942, 5 th instar larval length: 12.00– 23.40 mm; Ulmer 1909, larval length: 22.00–24.00 mm, larval width: 3.00– 3.50 mm). Maximum width of larva at metathorax.

Colour: Live specimen greenish, dorsally with dark areas and light stripes, pale ventrally. Specimens preserved in ethanol reddish brown, dorsum dark, ventrally pale; on abdomen, semicircular pale anterior dorsolateral areas, dorsocentral area of segments with irregular pale spots, connected with anterior dorsolateral areas. Sclerotized areas of head and thorax brown with pale areas and stripes, black in some places ( Fig 21a ).

Head ( Figs 4 , 21b ). Length: 1.49–2.20 mm ( = 1.90, n = 13). Width: 1.14–1.50 mm ( = 1.30, n = 13). Maximum width in posterior third of head, lateral margins almost parallel. Cephalic capsule ( Figs 4a, 4b ), dorsally and dorsolaterally light brown in anterior third, areas adjacent to frontoclypeal and anterior coronal sutures and anterior dorsolateral areas paler; ventral side variable ( Silfvenius 1905), pale ( Pitsch 1993), or with dark spots in middle central area ( Sedlák 1985, p. 111, table 3, fig 10); anterior edge and submentum reddish brown, posterior edge black ( Nielsen 1942); oval brown area with dark spots extending laterally from anterior edge of occipital foramen to anterior third of head ( Fig 4b ) ( Klapálek 1893; Lepneva 1964, p. 223, figs 181, 182B). Frontoclypeal apotome ( Fig 4c ) pale; 2 oval dark brown muscle attachment spots in central anterior third, between setae #4; dark pigmentation in posterior third heart-shaped, including pits #4 but not setae #6, with 4–6 oval brown muscle attachment spots with dark borders ( Klapálek 1893; Silfvenius 1905; Nielsen 1942; Lepneva 1964; Pitsch 1993). Two-thirds of posterior dorsal area of head light brown, marked with darker muscle attachment spots; centrally one pair of dark brown patches, wing-shaped, outside posterior edge of frontal suture; light circular area on juncture of frontal and coronal sutures; three pale spots around setae #15, #16, and #19–21; dorsal head pits with dark border, central posterior occipital foramen black.

Mandibles ( Fig 5 ) asymmetrical, as in other rhyacophilids; left one bigger than right one. Inner blade of left mandible irregular, convex, right mandible with small tooth in middle ( Nielsen 1942, pl. 2, fig 13; Lepneva 1964, p. 223, fig 184). Labrum and maxillolabium as in other Rhyacophila species ( Nielsen 1942, pl. 2, figs 12A, 12B, 14A, 14B; Lepneva 1964, p. 223, figs 183A, 183B, 185). Mentum rectangular, its anterior half slightly sclerotized. Labrum with small transparent area in central anterior edge.

Thorax ( Figs 6 , 21c ): Anterior half of pronotum pale or very light coloured. Sinuous posterior margin bordered by dark band, brown in middle of each half, black posteromesally and posterolaterally, light brown submesally; posterior half of pronotum ( Fig 6a ) with three dark areas separated by light zones, central dark region tapered posteriorly and reaching posterior edge of sclerite, anteriorly truncate, wider that posteriorly, two lines of dark brown spots inside central dark region and reaching posterior edge, several dark brown spots along posterior edge; each pronotal plate with lateral dark area almost triangular, from anterior submesal region to posterolateral edge of sclerite, posterior area with two–three rows of brown spots with dark borders distributed in circular-oval shape and parallel to posterior border. Four–six brown spots around setae #5; curved row of dark dots from setae #5 toward anterior submesal corner, curving around circular spot on anterior half ( Fig 6a ); pale posterior and median areas connected ( Fig 6b ); with narrow black band in anterolateral angles, extending posterad laterally to posterolateral margins, inner to margins ( Fig 6b ; Lepneva 1964); anterior margin light brown, with black spot near anterolateal angle; central area of posterior marginal band of each sclerite dark brown or black ( Fig 6b ) ( Nielsen 1942, pl.3, fig 17A; Lepneva 1964, p. 223, fig 188).

Legs ( Fig 9 ): Similar to those other Rhyacophila species. Colour yellowish, proximal regions of coxa, femur and distal region of trochanter of fore- and midlegs black or dark brown. Narrow pale reddish-brown band in proximal dorsolateral area of tibia and distal dorsolateral area of femur of each pair of legs, each inner and outer face of each femur with band of circular spots. Forelegs each ventrally with spicules, extending from distal half of trochanter, all of femur, and distal two-thirds of tibia and tarsus. Setae black or dark brown, some transparent in ventral area.

Abdomen ( Figs 7, 8 , 21d, 21e ): Similar to other Rhyacophila species. Colour as for meso- and metathoracic segments, greenish with dark dorsal areas and light stripes in living larvae, in preserved specimens semicircular pale anterior dorsolateral areas, dorsocentral area of segments with irregular pale spots, connected with anterior dorsolateral areas, pale yellow ventrally. Widths of anterior abdominal segments similar, narrower in posterior segments. Lateral abdominal gills in tufts of 25–30 filaments (20–30 filaments, Lepneva 1964). Dorsal sclerite of segment IX ( Figs 7 , 21d ) brown, with continuous black band on anterior edge and two small and widely separated black bands on posterior edge, under setae #2 ( Lepneva 1964); band of anterior edge narrower in center, with pair of narrow extensions backward beyond and surrounding pit #1; with some brown spots submesally near posterior margin; in darker larvae, extensions of anterior edge and spots of posterocentral area connected by dark stripes, creating X-shape figure; three pale areas along posterior margin, on either side of two black bands and central area. Anal prolegs typical of group, each with long sword process ( Figs 8a, 8b , 21e ). Anal claws each with three short teeth on ventral edge ( Figs 8a, 8c , 21e ), basoventral hook black basally and reddish brown apically ( Figs 8a, 8b ).

Description of the pupa

Biometrics of pupa and cocoon. Pupal length (total): 9.70–15.70 mm ( = 12.20, n = 28); male pupa: 10.07– 12.28 mm ( = 11.06, n = 11) (length: 11.20–12.20, Lepneva 1964; Nielsen 1942); female pupa: 9.70–15.70 mm ( = 12.94, n = 17) (length: 12.40–15.50, Lepneva 1964; Nielsen 1942; up to 16.00 mm, Silfvenius 1905). Cocoon length (total): 12.37–18.35 mm ( = 15.11, n = 68) (length: 12.50–18.00 mm, Nielsen 1942); male cocoon length: 12.39–16.27 mm ( = 14.43, n = 10); female cocoon length: 13.43–17.73 mm ( = 15.99, n = 16).

Head: Distribution of dorsal setae: four before, two between and two in middle of antennal pads, three on posterior edge of each cephalic tubercle. Mandibles brown, left one with two large teeth and right one with three, with numerous fine teeth on inner blade ( Klapálek 1893; Nielsen 1942; Ulmer 1909). Antennae of variable length, reaching from middle of abdominal segment IV to posterior edge of segment VI (to anterior edge of segment IV in females and posterior edge of segment VI in males, Klapálek 1893; to abdominal segment VIII in males and V in females, Lepneva 1964; Nielsen 1942).

Thorax: Tubercles of prothorax each with 5 setae, directed backwards, two central setae directed forwards. Hind wing pads variously reaching from anterior edge of abdominal segment III to posterior edge of segment IV (forewing pads reaching anterior edge of abdominal segment IV, Klapálek 1893; forewing pads reaching abdominal segment V in males and IV in females, Lepneva 1964; hind wing pads reaching end of segment IV in females, Silfvenius 1905).

Abdomen: Paired anterior hook plates pedunculated, straight basally and dilated posteriorly, palmate, and present on abdominal terga IV to VII ( Fig 10 ) ( Lepneva 1964; Ulmer 1909), slightly bigger on segments V and VI, each with 15–20 spines; also, pair of inconspicuous small flat plates without spines on tergum III. Paired posterior hook plates sessile on terga III–V, slightly oblong tranversally (length: width = 1:1.3) ( Klapálek 1893: paired anterior hook plates present on abdominal terga III to VIII, paired posterior hook plates on terga III to V; Silfvenius 1905: paired anterior hook plates present on abdominal terga IV to VII, sometimes without plates on segment III, paired posterior hook plates present on terga III to V), each with variable number of spines, more than 25.

Description of the imago

Male body length: 7.04–10.46 mm ( = 9.23, n = 36) each forewing: 10.16–13.54 ( = 11.67, n = 36), each hind wing: 8.52–11.99 mm ( = 10.25, n =36); females, length: 8.73–12.19 mm ( = 10.46, n = 19), each forewing: 10.05–13.90 mm ( = 12.14, n = 19), each hind wing: 8.24–12.03 mm ( = 10.68, n = 19) [ Ulmer 1909: male length ( R. fasciata ) = 10.00 mm, wingspan = 27.00 mm; male length ( R. septentrionis ) = 6.50–9.00 mm, wingspan = 22.50– 29.00 mm; Malicky 2004: male forewing length = 10.00–14.00 mm, female forewing length = 11.00–14.00 mm].

Colour: Specimens preserved in ethanol reddish brown dorsally, yellowish ventrally, spurs reddish, setae golden brown, females generally darker than males; small black or dark brown spots in dorsal area; in lateral view, some specimens with large black spots marking border between dorsal and ventral areas. Forewings dark with small pale spots, three transversal dark bands (fascias) in dry specimens ( Fig 30a ), pale in preserved specimens, darker in females, hind wings pale: each with dark area on leading edge between subcostal (Sc) and second radial (R 2) veins in fore- and hind wings; each forewing hyaline in irregular zone connecting medial (M) and medio-cubital (m-cu) veins and in distal area of second cubital vein (Cu 2) ( Holzenthal et al. 2007); in each hind wing proximal segment of medial veins and connection area (M 1-4) not conspicuous, second cubital (Cu 2) and first anal (A 1) veins not conspicuous either totally or partially, proximal portion of cubital vein (Cu) and distal portions of first cubital vein (Cu 1a-1b) thicker.

Male genitalia ( Figs 2b , 12 , 23 , 30b ): Apical segment of each inferior appendage ( Figs 2b , 12A , 23a ) with basal and distal edges diverging, dorsal and ventral edges diverging, posterior edge of 2nd segment of each inferior appendage slightly concave dorsally and slightly convex ventrally, ventral edge slightly concave ( Figs 12A , 23a ). Apicodorsal vertex slightly angular, apicoventral angle rounded, projecting as thick lobe narrowing progressively to apex.

Parameres in ventral view curved posteromesad in apical half ( Figs 12 BV p, 23c). In lateral view ( Fig 12 BL) each constricted at short distance beyond base, dilated at middle, with almost parallel dorsal and ventral margins in central area (S-shape), two files of long and thick spines on midventral margin, pointing outward; midlateral surface covered by sparse thin spicules or setae, from middle posteroventral to posterodorsal edge and covering most of apex, absents in middle anteroventral and dorsal edges.

Aedeagus (phallicata) in lateral view ( Fig 12 CL) with dorsal margin concave and posterior corner of concavity hooked anterad, posterior edge of aedeagus straight, projected posteroventrad, subapically rounded ventrally ( Fig 12 CL); ventral lobe of aedeagus triangular ( Fig 12 BV vl), lateral edges slightly rounded; lateroventral lobes of phallus straight, posterior edges strongly convex, apicolateral margins rounded ( Fig 12 CD lvl).

Apicodorsal lobe of segment IX slightly dilated subapicolaterally, almost round in shape ( Figs 12 DD al, 23b), with small apicomesal excision in some specimens; preanal appendages ( Fig 12 DD pa) round, shorter than apicodorsal lobe, almost covered by it; in ventral view, apical band V-shaped ( Fig 12 DV ab) nearly as wide as long, non-sclerotized inside area with posteromesal excision, posterior edges rounded ( Fig 12 DV va), anal sclerites triangular ( Fig 12 DV as).

Female genitalia ( Figs 13 , 25 ): In lateral view ( Figs 13 La, 13Lb, 25L), posterodorsal margin of segment VIII valves on each side irregular posteriorly, convex on ventral edge, with dorsolateral projection, in some specimens slightly indented posteriorly, posterolateral margin irregular, with 1–2 posterior projections, ventral projection more conspicuous ( Fig 13 Lb 1–3).

In dorsal view ( Figs 13 Da, 13Db, 25D), with indentation between segment VIII valves, with rounded apical and subapical corners, delimiting oval space, small projection in apical corner in some specimens ( Fig 13 Db).

In ventral view ( Fig 13V , 25V ) segment VIII valves forming two elongate sclerites, basal 1/4 of mesal edges parallel, distal 3/4 of mesal edges irregular, slightly concave, diverging; intersegmental membrane with pair of dark, ovoid or slightly elongate sclerites.

Figures

FIGURE 2. Lectotype of Rhyacophila fasciata Hagen 1859, in the Entomology Collection of the Museum of Comparative Zoology of Harvard University (Cambridge, MA, USA; MCZ). 2a, labels and male genitalia in cork-stoppered microvial. 2b, genitalia of Rhyacophila fasciata lectotype (male). Reproduced with permission of MCZ.

FIGURE 9. Rhyacophila fasciata Hagen 1859, right legs. 9A, anterior views; 9P, posterior views. I–III: pro-, meso-, and metathoracic legs, respectively. Scale bar: 1 mm.

FIGURES 4–8. Larva of Rhyacophila fasciata Hagen 1859. 4a–4c, head: 4a, dorsal; 4b, right lateral; 4c, frontoclypeus, dorsal. 5D, 5V, mandibles from last instar larval exuviae, left (l) and right (r): 5D, dorsal; 5V, ventral. 6a, 6b, prothorax: 6a, dorsal; 6b, left hemisclerite, left lateral. 7, dorsal sclerite of abdominal tergum IX. 8a–8c, details of anal prolegs: 8a, right anal claw, right lateral; 8b, detail of basolateral plate with sword process and basoventral hook, right lateral; 8c, detail of claw, right lateral. Scale bar: unlabelled = 1 mm; ● = 0.5 mm.

FIGURES 21, 22. Larvae of Rhyacophila fasciata Hagen 1859 and Rhyacophila septentrionis McLachlan 1865.21, Rhyacophila fasciata: 21a, head and protorax, dorsal; 21b, detail of head, dorsal; 21c, detail of prothorax, dorsal; 21d, dorsal sclerite of abdominal tergum IX, dorsal; 21e, left anal proleg, left lateral. 22, Rhyacophila septentrionis: 22a, head and protorax, dorsal; 22b, detail of head, dorsal; 22c, detail of prothorax, dorsal; 22d, dorsal sclerite of abdominal tergum IX, dorsal; 22e, left anal proleg, left lateral. Scale bar: 1mm.

FIGURES 10, 11. Rhyacophila fasciata Hagen 1859 and Rhyacophila septentrionis McLachlan 1865, paired abdominal hook plates of male pupa. 10l and 10r, Rhyacophila fasciata left and right hook plates, respectively. 11l and 11r, Rhyacophila septentrionis left and right hook plates, respectively. A = anterior hook plates, dorsal, P = posterior hook plates, dorsal; III–VII = abdominal terga III through VII, dorsal. Scale bar: 50 µm

FIGURES 30–33. 30. Lectotype of Rhyacophila fasciata Hagen 1859 (male). 30a, thorax and right forewing (pinned); 30b, abdomen and male genitalia in cork-stoppered microvial (ethanol), detail. Photos: Museum of Comparative Zoology of Harvard University, Cambridge, MA, USA (MCZH). 31–33. Rhyacophila septentrionis MacLachlan 1865. 31, lectotype (male): 31a, specimen (pinned); 31b, apicodorsal lobe of segment IX and preanal appendages, dorsal view; 31c, detail of genitalia, posterior view. 32, female: 32a, cleared and mounted genitalia; 32b, original mounting preparation. 33, original mounting preparation of R. septentrionis male genitalia. Photos: Ben Price, Natural History Museum of United Kingdom (NHMUK).

FIGURES 12, 13. Male and female genitalia of Rhyacophila fasciata Hagen 1859. 12, male: 12A, 2nd segment of left inferior appendage, left lateral; 12BV, 12BL, parameres: 12BV, parameres (p) and ventral lobe of aedeagus (phallicata) (vl), ventral; 12BL, left paramere, left lateral. 12CL, 12CD, aedeagus (phallicata) and lateroventral lobes: 12CL, aedeagus and ventral lobe, left lateral; 12CD, aedeagus and lateroventral lobes (lvl), dorsal. 12DD, apicodorsal lobe of segment IX (al) and preanal appendages (pa); 12DV, segment X, ventral, ab= apical band, as = anal sclerites, va = non-sclerotized ventral area. 13, female segments VIII–XI: 13La, left lateral; 13Lb, left lateral, posterolateral edge of segment VIII valves variations: 1 = two specimens from Finland, 2 = three specimens from Czech Republic and Slovakia, 3 = one specimen from Croatia; 13Da, dorsal; 13Db, posterodorsal edge of segment VIII valves variations; 13V, ventral. Scale bars: unlabelled = 1 mm; ● = 0.5 mm; * = 200 µm.

FIGURES 23–26. Males and females of Rhyacophila fasciata Hagen 1859 and Rhyacophila septentrionis McLachlan 1865. 23, male of Rhyacophila fasciata: 23a, 2nd segment of left inferior appendage, left lateral; 23b, apicodorsal lobe of segment IX and preanal appendages, dorsal; 23c, parameres and ventral lobe of aedeagus (phallicata), ventral; 23d, left paramere, left lateral. 24, male of Rhyacophila septentrionis: 24a, 2nd segment of left inferior appendage, left lateral; 24b, apicodorsal lobe of segment IX and preanal appendages, dorsal; 24c, parameres and ventral lobe of aedeagus (phallicata), ventral; 24d, left paramere, left lateral. 25, female segments VIII–XI of Rhyacophila fasciata: 25L, left lateral; 25D, dorsal; 25V, ventral. 26, female segments VIII–XI of Rhyacophila septentrionis: 26L, left lateral; 26D, dorsal; 26V, ventral. Scale bars: Figures 23a–c, 24a–c = 0.5 mm, Figures 23d, 24d = 200 μm, Figures 25, 26 = 1 mm.