Macrostemum arcuatum (Erichson 1848), Erichson, 1848

França, Diogo, Paprocki, Henrique & Calor, Adolfo R., 2013, The genus Macrostemum Kolenati 1859 (Trichoptera: Hydropsychidae) in the Neotropical Region: Description of two new species, taxonomic notes, distributional records and key to males, Zootaxa 3716 (3), pp. 301-335: 309

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Macrostemum arcuatum (Erichson 1848)


Macrostemum arcuatum (Erichson 1848)  

Figs. 4 View FIGURE 4 A –E

Macronema arcuatum Erichson 1848: 586   [type locality: by inference, “British-Guiana”; MCZ; ♂]. Flint 1974: 105, 106, Plate 1 [♂; distribution; wings]; Flint 1978: 388, 412, 416 [distribution; ♂; wings];

Pseudomacronema arcuatum (Erichson 1848)   ; Ulmer 1907 a: 40, Plate 1 [wings; ♂]; Mosely 1931: 170 [distribution]; Fischer 1963: 163 [bibliography, distribution].

Macrostemum arcuatum (Erichson 1848)   ; Flint 1996: 412 [distribution]; Flint et al. 1999: 68 [taxonomic notes; distribution]; Paprocki et al. 2004: 8 [distribution]; Nogueira & Cabette 2011: 349 [distribution].

Macrostemum arcuatum   is unique and unmistakable among species of Macrostemum   . The characters that differentiate this species from all others include one quadrate wart on the dorsal proximal region of abdominal segment X and a phallotremal sclerite bearing a pair of laminated dorsal processes. In addition, a distinctly hyaline N-shaped patch on the medial area of each forewing aids in its identification.

Synopsis. Adults pinned. Forewing mean length 9.9 mm (9.43–10.85 mm, n= 35). Head brown, with or without yellow spot behind eyes. Compound eyes brown. Scapes golden, with brown setae. Maxillary palps golden, with golden setae. Prothorax golden. Meso- and metathorax dark brown, with lateral light brown spots. Legs golden. Tibial spur formula 2,4, 4. Forewings dark, with hyaline marks, each bearing distinct hyaline N-shaped spot on medial area; discoidal cell absent; radial sector markedly expanded ( Fig. 4 View FIGURE 4 A).

Male genitalia. Abdominal segment IX, in lateral view, with anterior and posterior margins sinuous; posterior margins deeply notched above middle and with long setae bordering margin above and below notch on each side ( Fig. 4 View FIGURE 4 B); in dorsal view with posterior margin bearing medial truncate keel and long setae along right and left posterior margins ( Fig. 4 View FIGURE 4 E). Segment X, in dorsal view, bilobed, each lobe apically rounded and with subapical wart ( Fig. 4 View FIGURE 4 E); in lateral view, tapered to rounded apex with one quadrate subdorsal wart on each side near base ( Fig. 4 View FIGURE 4 B). Inferior appendages almost uniformly wide and covered uniformly by small setae; each with basal segment approximately two times length of apical segment, with longer setae at dorsal apex of basal segment, apical segment slightly upcurved and apically blunt ( Fig. 4 View FIGURE 4 B). Phallus arched near base; apex, in lateral view, truncate, with rectilinear posteroventral prominence ( Fig. 4 View FIGURE 4 C); phallotremal sclerite slender, bearing pair of laminated anterodorsal processes, with medial portion straight, transverse, and ends curved anterolateral ( Fig. 4 View FIGURE 4 D); phallotrema rounded, concave, on posterior apex of phallus ( Fig. 4 View FIGURE 4 D).

Material examined. BRAZIL: Amazonas: Barcelos, Serrinha, Rio Aracá, 0 0o 24 ’39,7’’N, 63 º 23 ’ 12 ’’W, 28.vii. 2009, luz do barco, A. Pes leg., 2 males (alcohol; INPA); Mato Grosso: Nova Olimpia, Fazenda Bandeirantes, Usinas Itamarati, Rio Bugres, 26.xii. 2002, luz, A. R. Calor & C. T. Salgado leg., 7 females (pinned; UFBA); Ribeirão Cascalheira, 1 º córrego (estrada Fazenda Manaus), 2.xii. 2006, luz, Calor & Silva leg., 1 male (pinned; UFBA); same data, 19 females (pinned; UFBA); same data except, 1.xii.2006, 6 females (pinned; UFBA); same data except Córrego Represa, 27.xi. 2006, luz, Calor, Silva, Mateus leg., 1 female (pinned; UFBA); Tangará da Serra, Fazenda Calcário Tangará, Grupo Itamarati, Rio Sepotuba, 3.i. 2003, puçá, A. R. Calor leg., 1 female (pinned; UFBA); Pará: Rio Xingu, Camp (3 º 39 ’S, 52 º 22 ’W), ca 60 km S. Altamira, x. 1986, P. Spangler & O. Flint leg., 2 males, 13 females (pinned; MZSP); (?) State [Mato Grosso State]: estrada da colônia, Aripuanã, Y. T., 22.i. 1975, L. P Albuq. & E. L. Antony leg., 1 male (pinned; INPA); SURINAM: Marowijne: Benzdorp, Rio Lawa, xi. 1963, B. Malkin leg., 2 males (alcohol; MZSP).

Distribution. Brazil (AM, MT, PA), Guyana, Peru and Surinam.