Macrostemum araca, Pes & Desidério & Barcelos-Silva & Hamada, 2019

Pes, Ana M., Desidério, Gleison R., Barcelos-Silva, Patrik & Hamada, Neusa, 2019, A new species of Macrostemum Kolenati, 1859 from Brazilian Amazon and the immature stages of M. brasiliense (Fischer, 1970) (Trichoptera: Hydropsychidae), European Journal of Taxonomy 534, pp. 1-20: 4-9

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Macrostemum araca

sp. nov.

Macrostemum araca   sp. nov.

Figs 1–5 View Fig View Fig View Fig View Fig View Fig


Macrostemum araca   sp. nov. male is similar to M. braueri   and M. surinamense   males by having phallus apex with long posterolateral and acuminate prominence, but it can be distinguished from these species by the shape and number of setae on tergite IX with 20 long dorsal setae and 9 lateral setae, while M. braueri   has 7 long dorsal setae and 7 lateral setae and M. surinamense   has 15 long dorsal setae and 8 lateral setae. Additionally, the color pattern of forewing in the new species is yellow with 2 darkbrown vertical bands on the distal half, the apical ⅓ is dark brown with an elongated median hyaline spot, while in M. braueri   the forewing is mostly hyaline, each with one dark band bordering apical area and delimiting one boot-shaped hyaline area, and in M. surinamense   the forewing is dark-brown with only two small hyaline bands in apical area.

The female of Macrostemum araca   sp. nov. can be recognized by the sternum VIII divided almost completely along the midline into two oval plates and tergum IX with a row of long setae on the posterior margin dorsally.


The specific epithet is a noun in apposition that refers to the Serra do Aracá mountain range, which is the type-locality of the new species.

Material examined


BRAZIL: • ♂; Amazonas, Barcelos, Parque Estadual Serra do Aracá, Igarapé da Cobra no Acampamento (# B 01); 00°52′24.78″ N, 63°27′18.97″ W; alt. 136 m; 30 Jul.–2 Aug. 2009; A. P. M. Santos, J. O. Silva, J. L. Nessimian, N. Ferreira Jr., U. G. Neiss and F. F. Salles leg.; INPA. GoogleMaps  


BRAZIL: • 1 ♂, 10 ♀♀; same data as for holotype; 25 Jul. 2009; A. P. M. Santos leg.; INPA GoogleMaps   5 ♂♂, 1 ♀; same data as for holotype; 27 Jul.– 2 Aug. 2009; INPA GoogleMaps   4 ♂♂, 4 ♀♀; same data as for holotype; 4– 5 Aug. 2009; INPA GoogleMaps   1 ♂, 2 ♀♀; same data as for holotype; Igarapé do Jabuti (# B 07); 00°52′47.78″ N, 63°28′27.05″ W; alt. 125 m; 27 Jul. – 4 Aug. 2009; A. P.M. Santos, J.O. Silva, J.L. Nessimian, N. Ferreira Jr., U.G. Neiss and F.F. Salles leg.; INPA GoogleMaps   2 ♂♂, 1 ♀; same data as for holotype; Igarapé da Cobra (#B08); 00°52′34.21″ N, 63°27′03.60″ W; alt. 157 m; 2–5 Aug. 2009; A.P.M. Santos, J.O. Silva, J.L. Nessimian, N. Ferreira Jr., U.G. Neiss and F.F. Salles leg.; INPA GoogleMaps   1 ♂; same data as for holotype; Comunidade Serrinha , Rio Aracá; 00°25′25.8″ N, 63°23′47.0″ W; alt. 69 m; 28 Jul.–6 Aug. 2009; N. Hamada, A.M. Pes, R.L.F. Keppler, C.A.S. Azevedo and C. Monteiro leg.; INPA GoogleMaps   1 ♀; Barcelos , [neighboring the] Serra do Aracá; 00º52′24″ N, 63º27′19″ W; alt. 149 m; Jul.–Aug. 2007; A. Filho leg.; INPA GoogleMaps   .


Adult male ( Figs 1 View Fig A–G, 2A–B)

Length of forewing: 10.91–12.69 mm (mean = 10.42 mm, SD = 0.59, n = 9).

General color dark-brown and golden-yellow (in alcohol) ( Fig. 1 View Fig A–F).Antennae basal ⅓ (approximately) dark-brown, apical region yellow; scape 2 × longer than wide, with base slightly enlarged; pedicel short and broad. Head and setae dark-brown with some dark setae and anterior setal wart pale-yellow, covered with yellow setae, posterior setal wart brown, covered with brown setae, palps and haustellum paleyellow ( Fig. 1 View Fig B–C). Thorax, pronotum yellow covered with pale-yellow setae, meso- and metanotum dark-brown covered with brown setae; foreleg tibia and tarsus brown, mid and hind legs coxae and femora light-brown to yellow. Tibial spur formula 2,4,4. Midleg tarsus flattened. Forewing completely golden-yellow in basal region, with basal half without bands or spots, distal half with two vertical brown bands, the apical ⅓ is golden-brown with an elongated hyaline spot between veins R5 – M1 (may be open in the anterior region, Figs 1E View Fig , 2A View Fig ) with light spots above and below (variable from pale-yellow to light-brown until almost imperceptible), entire wing covered with fine setae, light-brown (in alcohol) ( Fig. 1 View Fig D–E); veins Sc and R1 fused near apex, forks I–V present, forks I and IV petiolate; discoidal cell small, median cell moderately in size, thyridial cell very long. Nygma and thyridium present. Hindwing almost totally golden-yellow, only with a small dark-brown triangle medially and a dark-brown band in the apical area; anal area large, veins Sc thickened and contiguous with R1 near apex; fork II, III and V present, fork V petiolate, discoidal and median cell absent, nygma present, veins between Cu and A vein anastomosed ( Figs 1F View Fig , 2B View Fig ). Sternum V, with long anterolateral glandular processes, 1.2 × longer than sternums V and VI, with basal opening and reticulated filament ( Fig. 1G View Fig ).

MALE GENITALIA. ( Fig. 3 View Fig A–I). Segment IX, in lateral view ( Fig. 3A View Fig ), with anterolateral margin slightly sclerotized and sinuous, delimited by 20 long dorsal setae and 9 scattered setae at ventral half, anterior margin almost straight; in dorsal view ( Fig. 3B View Fig ), posterior margin with triangular median keel, two lateral lobes with cluster of long setae. Segment X in lateral view ( Fig. 3A View Fig ) subtriangular, apex rounded, with subdorsal cluster of small setae near midlength, apex with smalls setae; in dorsal view ( Fig. 3B View Fig ) bilobed, each lobe with thick and short setae, mesal incision wide, forming deep, wide V-shape, reaching half-length of segment X. Inferior appendages, in lateral view ( Fig. 3A View Fig ), two-segmented, basal segment long, apical segment short, about ⅓ of the total length, apex rounded and slightly clavate, covered uniformly by long (external) and short (internal) setae; in ventral view ( Fig. 3C View Fig ) covered uniformly by long (external) and short (internal) setae. Phallus tubular, with apex dilated, forming long acuminate posterolateral prominence ( Fig. 3 View Fig D–I); in ventral view ( Fig. 3 View Fig H–I) phallotremal sclerite in shape that resembles a mushroom with 2 small apical lobes, phallotrema arrow-shaped; in dorsal view ( Fig. 3 View Fig F–G) opening of the annular phallotrema dorsally positioned.

Adult female

Length of forewing: 9.26 – 11.46 mm (mean = 10.42 mm, SD = 0.68, n = 10).

General color pattern, tibial formula, and glandular process of sternite V similar to male, differing only in the posterior setal wart, which is smaller, more triangular and not so prominent. Venation of the fore wing and hindwing similar to that of male, but the anal area of the posterior wing is about 1 ∕ 5 narrower than the wing of the male.

FEMALE GENITALIA. ( Fig. 4 View Fig A–D). Sternum VIII divided almost completely along the midline into two plates, each oval-shaped, covered with setae across the surface ( Fig. 4A, C View Fig ). Tergum IX anterior region with reticulated cuticle, similar to an irregular honeycomb, each cell with 3 to 4 short setae; in lateral view, apex with small setae; in dorsal view ( Fig. 4B View Fig ), posterior margin with a row of long setae. Tergum X small and narrow, almost entirely covered by tergum IX ( Fig. 4A, C View Fig ). Sternum X ending with 2 pairs of distinct papillae; a pair of biarticulated cerci positioned between the papillae in ventral and lateral views ( Fig. 4A, C View Fig ). Internal vaginal apparatus complex, with posterior sclerite triangular, anterior sclerite annular, wider in the median region, with two lateral projections, lateral valve long and narrow, rod-shaped ( Fig. 4D View Fig ).

Immature stages


Taxonomic remarks

Female genitalia of the Neotropical Macrostemum   species have not been described or illustrated, so we cannot compare this structure with other species from the region. Some species from the Oriental Region have female genitalia illustrated and described ( Hoang et al. 2005). The oval-shaped ventral plate of sternum VIII is somewhat similar to that of M. floridum Navás, 1929   , but in M. araca   sp. nov. it is broader at the base, and the ventral and dorsal papillae are more dilated.


This species was collected in the Rio Aracá (a large river, with 200–250 m of the width) ( Fig. 5E View Fig ) and in some of its small tributaries (with 1–5 m of the width), all with black water, in a forested area ( Fig. 5 View Fig C– D) located at the base of the Serra do Aracá, in the Brazilian Amazon ( Fig. 5A View Fig ).


Brazil (Amazonas).


Field Museum of Natural History, Botany Department


Botanischer Garten und Botanisches Museum Berlin-Dahlem, Zentraleinrichtung der Freien Universitaet


University of Copenhagen


Botanische Staatssammlung München


Nanjing University


Naturhistorisches Museum Wien


Harvard University - Arnold Arboretum


Instituto Nacional de Pesquisas da Amazonia