Smicridea (Smicridea) obliqua Flint 1974

Albino, Jeyson Lazaro Duque, Pes, Ana Maria & Hamada, Neusa, 2011, Smicridea (Trichoptera, Hydropsychidae) from 3 Brazilian Amazonian States: New species, larval taxonomy and bionomics, Zootaxa 3113, pp. 1-35 : 25-29

Smicridea (Smicridea) obliqua Flint 1974

Figs 70–82

Smicridea (Smicridea) obliqua Flint 1974: 90 ; Flint 1978: 398; Flint et al. 1999: 74.

Pupa. Length 4.5–5.0 mm (n = 5) thorax and abdomen with sparse setae.

Pupal head. Labrum with central lobe slightly rounded in shape, about 4 times as broad as either of the lateral lobes, covered with 22 mediam setae; lateral lobes rounded, each with 5 long setae in dorsal view ( Fig. 70 ). Mandibles asymmetrical and broad basally, right mandible with 3 mesal teeth and 1 apical tooth and left mandible with 4 mesal teeth and 2 apical teeth; each mandible with brush of long setae on posterolateral portion ( Fig. 71 ).

Pupal thorax. With sparse setae.

Pupal abdomen. With sparse setae. In dorsal view, with pairs of hook plates on anterior portion on segments II– VIII, posterior portion on segments III–IV; in hook-plate pair 2a each plate with 2 strong, straight hooks and 5 smaller ones; in hook-plate pair 3a each plate with 2 strong and 5 small hooks, in hook-plate pair 3p each plate with 3 strong and 5 small hooks; in hook-plate pair 4a each with 3 strong and 5 small hooks, in hook-plate pair 4p each plate with 3 strong retrorse hooks; in hook-plate pair 5a each plate with 3 strong and 5 small hooks; in hook-plate pair 6a each plate with 3 strong and 3 small hooks; in hook-plate pair 7a each plate with 3 strong hooks and 1 small hook; in hook-plate pair 8a each plate with 2 strong and 2 small hooks ( Fig. 73 ). Abdominal apical processes on segments IX–X straight, widely separated, each cylindrical with apical brush of setae (8 short and 11 long) ( Fig. 72 ).

Larva (Figs 74–82). Length 4.5–6.0 mm (n = 8). Color in alcohol yellow-brown, lateral habitus as in Figure 75; body covered with sparse short, spatulated setae.

Larval head. Round in dorsal view (Fig. 75). Yellow-brown with 2 large dark brown spots on median region, anterior part of frontoclypeus darker than posterior part; pair of dark areas ventrolaterally and laterally (Figs 75– 77). Dorsal and lateroventral regions covered with short setae; 1 pair of long setae over eye (pair #9); 2 pairs of long setae, 1 on clypeus margin (pair #1) and other on lateral margins of eyes (pair #14), coronal suture short, 1 pair of median setae near clypeus anterior margin (pair #3) (Figs 75–77). Coronal suture short; frontoclypeal suture Vshaped; anterior margin of frontoclypeal apotome with median region lightly produced and crenulated, with small lateral lobes (Fig. 75). Labrum oval; covered by short, thin setae; fringe of very small, thin setae on anteromesal margin; pair of submesal setae near anterior margin; pair of brushes of long, submarginal setae laterally ( Fig. 81 ). Mandibles asymmetrical, left mandible with 4 mesal teeth, 1 subapical tooth, 1 apical tooth, brush of submarginal setae at mid length; right mandible with 5 mesal teeth, 1 subapical tooth, 1 apical tooth, and no submarginal setae; both mandibles fringed laterally with moderately long hairs ( Fig. 80 ). In ventral view, stridulation file on each gena short, wide with thin, transverse lines (Fig. 78). Ventral apotome divided, anterior portion triangular, well sclerotized anteriorly (Fig. 76).

Larval thorax. Notal sclerites brown-yellow, covered with short thin setae; pronotum with longitudinal ecdysial line, anterior and posterior margins with dark, thick lines, forming 2 horizontal dark bands with light area in between; meso- and metanota without longitudinal ecdysial lines (Figs 74, 79). Gills absent on prosternum; mesosternum with 2 pairs of ventral gills, metasternum with 1 pair of simple central gills and 3 pairs of simple ventrolateral gills; each gill with elongated stalk, few filaments arising irregularly. Legs similar, although prothoracic leg somewhat shorter than meso- and metathoracic legs (Fig. 74); foretrochantins simple.

Larval abdomen. Two pairs of gills on abdominal segment I, 1 pair of simple gills and 1 pair of double gills ventrally on abdominal segments II–VII, 1 pair of simple, ventrolateral gills on segment VIII; sternum VIII with single, small sternite, bordered posteriorly by 8 medium and 8 short setae ( Fig. 82 ).

Diagnosis. The pupa of S. obliqua differs from those of the other species by having on the labrum 22 medium setae on the central lobe and lateral lobes each with 5 long setae. The pupa is similar to those of S. truncata and S. palifera by having the labrum with the lateral lobes small and central lobe large. The pupa of S. obliqua also differs from those other species by the form of the hook plates, principally by hook-plate pair 3p being rounded, while in S. palifera and S. truncata the plates in this pair are wider than tall, while in S. annulicornis these plates are fused.

The larva of S. obliqua differs from those of the other species in the subgenus by the head pattern with 2 dark spots dorsomedially, 1 pair laterally, 1 pair ventrolaterally and 1 pair posteriorly and by having the anterior margin of the frontoclypeal apotome with median region lightly produced and crenulated. It is similar to the larva of S. frequens (Navás 1930) by having the head rounded in shape.

Biology. Adults were collected with light traps placed on streams with width 1.0– 8.5 m, sandy bottom, black water, pH 4.6–7.2, and preserved riparian vegetation with minor changes due to agriculture in terra firme areas of the Amazon forest biome. Larvae and pupae were collected in reaches with strong water velocity, where they were collected on leaves and roots.

Distribution. Suriname; Brazil, Amazonas State.

Material examined. BRAZIL, Amazonas, Presidente Figueiredo municipality, igarapé das Canoas, S 01º49'51" W 60º04'15” O, 05.ix.2001, A.M.O. Pes, light trap over white cloth and mixed light, 1 male [alcohol] ( INPA); AM 240, Km 24, Sitio do Sr. José Souza, S 02°01'06" W 59°49'27", 04–05.iv.2000, A.M.O. Pes, Pennsylvania trap, UV light, 4 males [alcohol] ( INPA); 28.IX a 2.X.2000, 7 males [alcohol] ( INPA); 03–04.vii.2000, 9 males [alcohol] ( INPA); 02–03.viii.2000, 5 males [alcohol] ( INPA); Manaus, Reserva Florestal Adolfo Ducke, Igarapé 22, camp, S -59,9039 W -2,99031, 18–21.viii.2006, A.M.O. Pes, Pennsylvania trap, UV light, 8 males [alcohol] ( INPA); Fazenda Dimona stream in secondary forest near the 10-ha fragment ( PDBFF), S-60,0549 W - 2,2022, 10.ii.2000, A.M.O. Pes, 10 pupae (2 pharate males) [alcohol] ( INPA).

Figures

FIGURES 70 – 73. Smicridea (Smicridea) obliqua Flint 1974, pupa. 70) Labrum, dorsal view; 71) mandibles, dorsal view; 72) right side of abdominal segments IX – X, dorsal view; 73) hook plates (left side, dorsal view; 2 – 8 = abdominal segment number, a = anterior, p = posterior), dorsal view.

FIGURES 80 – 82. Smicridea (Smicridea) obliqua Flint 1974, larva. 80) Mandibles, dorsal view; 81) labrum, dorsal view; 82) ventral sclerites on abdominal segment VIII, ventral view.