Smicridea (Rhyacophylax) necator, Rocha, Isabela Cristina, Dumas, Leandro Lourenço & Nessimian, Jorge Luiz, 2016

Rocha, Isabela Cristina, Dumas, Leandro Lourenço & Nessimian, Jorge Luiz, 2016, Three new species and a new record of Smicridea McLachlan 1871 (Trichoptera: Hydropsychidae) from Minas Gerais state, Brazil, Zootaxa 4107 (3), pp. 423-430 : 424-426

Smicridea (Rhyacophylax) necator sp. nov.

( Figures 1 A–E)

Description. Adult male. Length of each forewing 4.65–5.60 mm (n = 6). Color in alcohol yellow. Head and thorax golden, with setal warts yellow. Antennae and legs light yellow, legs with short brown setae. Forewings yellow, with dark brown setae, each wing with costal margin and pterostigma marked with white band; transverse veins, nigma and thyridial spots brown, transverse light brown band on distal region. Wing venation typical for subgenus. Length (0.25 mm) of anterolateral glandular processes of sternum V not surpassing posterior margin of this segment.

Male genitalia. Segment IX, in lateral view, with dorsal half trapezoidal, about 5 times as long as rectangular ventral half; anterolateral margin on each side slightly concave, with obtuse angle at half its height; ventral margin short; ventrolateral margin concave; dorsomesally with subapical protuberance bearing small spicules ( Fig. 1 A); in dorsal view, posterodorsal margin highly convex, covered apically with spicules; lateral margins almost parallelsided, slightly expanded basally ( Fig. 1 B). Tergum X setose, in lateral view, with tip rounded and directed dorsoposterad ( Fig. 1 A); in dorsal view, divided almost completely mesally, apices rounded apically and directed mesad; lateral margins sclerotized ( Fig. 1 B). Inferior appendages each two-segmented, basal segment long, slightly inflated in distal half, covered with long setae; apical segment slender, approximately 1/3 as long as basal segment ( Fig. 1 A); apex rounded in dorsal and lateral views ( Figs. 1 A, 1B). Phallus tubular, basal section enlarged and meeting apical section at about 100º angle; apex slightly enlarged, with wide aperture; apicodorsal region rounded and subtruncate apicoventrally ( Fig. 1 C). Internal sclerotized portion of ejaculatory duct, in ventral view, divided longitudinally into four branches subapically resulting in enlarged basket-shaped region, branches reunited in slender tube distally, ending in a double axe shape ( Figs. 1 D, 1E). Endothecal membranes, in ventral view, with arc of short spines at apical margin; projection in apicomesal region saddle-like, with anterior margin concave ( Fig. 1 D); in lateral view, with flame-like cluster of spines ( Fig. 1 C); when phallus expanded apical region mace-like and apicomesal projection with anterolateral tips spine-like ( Fig. 1 E).

Female and immatures. Unknown.

Diagnosis. Smicridea (R.) necator sp. nov. possibly belongs to the S. (R.) dispar Group (Flint 1974) by having a quite simple phallus, without major lobes apically, but its placement in this group is weakly supported. In the new species, the phallic apex is slightly enlarged and the subapical region of the ejaculatory duct has an expanded basket-like structure, ending apically in a double axe shape. The new species is somewhat similar to S. (R.) dispar ( Banks 1905) in the shape of the phallus apex, but can be distinguished by the different processes in the apical region of the endotheca: Smicridea (R.) necator sp. nov. possesses an arc of short spines in the apical region of endotheca, while S. (R.) dispar has a slender mesal process and a pair of darkened, lateral structures. Additionally, S. (R.) ralphi Almeida & Flint 2002 and the new species resemble each other in the shape of the segment IX in dorsal view. The posterodorsal margin is highly convex and covered apically with spicules in both species. However, the posterolateral margin is curved in S. (R.) necator sp. nov., but is straight in S. (R.) ralphi . Segment X, in dorsal view, is divided almost completely mesally in both species, but in S. (R.) ralphi the apices of segment X are not directed mesad as they are in the new species. Furthermore, the two species can be easily separated by the differing structure of the phallic apparatus: in S. (R.) ralphi the internal process of the phallus apex is upturned externally with tip pointed and lateral processes sinuate. In the new species the internal process has a double axe form and an apicomesal projection saddle-like.

Distribution. Brazil, Minas Gerais state.

Etymology. The specific epithet is a masculine noun in apposition, referring to the similarity of the phallus apex with the shape of the mouth of the parasitic nematode Necator americanus ( Stiles 1902).

Material examined. Holotype male: BRAZIL: Minas Gerais: Delfinópolis, surrounding area of the Parque Nacional da Serra da Canastra, afluente do Ribeirão Forquilha, 20°18’55.58”S, 46°49’59.04”W, el. 720 m, 26.iii.2015, JL Nessimian, LL Dumas, IC Rocha, ALH Oliveira & SP Gomes leg. ( DZRJ).

Paratypes: BRAZIL: Minas Gerais: Delfinópolis, surrounding area of the Parque Nacional da Serra da Canastra, afluente do Ribeirão Forquilha (Cachoeira do Ézio), 20°18’54.13”S, 46°49’53.35”W, el. 730 m, 26.iii.2015, JL Nessimian, LL Dumas, IC Rocha, ALH Oliveira & SP Gomes leg., 2 males ( DZRJ); Delfinópolis, surrounding area of the Parque Nacional da Serra da Canastra, afluente do Ribeirão Forquilha, 20°18’55.58”S, 46°49’59.04”W, el. 720 m, 26.iii.2015, JL Nessimian, LL Dumas, IC Rocha, ALH Oliveira & SP Gomes leg., 2 males ( DZRJ); Delfinópolis, surrounding area of the Parque Nacional da Serra da Canastra, afluente do Ribeirão Forquilha (Serro Alegre), 20°19’20.88”S, 46°50’21.14”W, el. 682 m, 27.iii.2015, JL Nessimian, LL Dumas, IC Rocha, ALH Oliveira & SP Gomes leg., 1 male ( DZRJ).

Figures

FIGURE 1. Male genitalia of Smicridea (Rhyacophylax) necator sp. nov., holotype: A, left lateral; B, dorsal; C – E, phallus: C, left lateral; D, apex, ventral, with magnified inset of projection; E, expanded apex, ventral.