Alterosa cornuta,

Novais, Christina, Dumas, Leandro Lourenço & Nessimian, Jorge Luiz, 2019, Two new species and a new distributional record of Alterosa (Trichoptera: Philopotamidae) from southeastern Brazil, Papéis Avulsos de Zoologia 59, pp. 1-7: 6

publication ID 10.11606/1807-0205/2019.59.52

publication LSID


persistent identifier

treatment provided by


scientific name

Alterosa cornuta

new species

Alterosa cornuta  , new species

( Figs. 3View Figure 3 A‑3D)

Diagnosis: Alterosa cornuta  sp. nov. is distinctive within the genus and cannot be easily placed in any of the species groups defined by Blahnik (2005). However, the new species share similarities with A. guapimirim Blahnik (2005)  and A. orgaosensis Blahnik (2005)  , regarding the general structure of the inferior appendages, with first article less than half length of the second. Alterosa cornuta  sp. nov. is easily diagnosed by the overall shape of the intermediate appendages with the apical half hornshaped and crossing each other over the apical half of tergum X, with each appendage slightly turned ventrad. Additionally, the inferior appendages each have a row of large spine-like setae on the inner margins that decrease in size to the base, which is also asymmetric on the right and left sides. Also, the endotheca has a tongue-like spinous plate, that differs from all others species of the genus.

Description: Adult: Color (in alcohol) golden-brown; legs, palps, and antennae pale-brown, forewing color pattern not discernible. Male forewings 6.24-7.20 mm (n = 6; holotype = 6.40 mm). Maxillary palps 5-articulated; 2 nd article with elongate setae at apicomesal portion; 3 rd article about 2x length of 2 nd; 5 th article elongate, about 3.5x length of 3 rd. Head setal warts well-developed, frontal setal warts large, rounded; anteromesal setal warts laterally fused to anterior setal wart M-shaped; posterior setal wart rounded; posterolateral setal warts large, robust and about ovoid.Tibial spurs formula: 2-4-4. Wing venation typical for the genus; forewings with forks I-V present, discoidal and thyridial cells similar in length; hind wings with forks I-III and V present.

Male genitalia: Tergum VIII with posteromesal margin rounded, not emarginate. Sternum IX with anterolateral margin moderately rounded; posteroventral margin sinuous, slightly produced; anterior submarginal tergal apodeme well-developed ( Fig. 3AView Figure 3). Tergum IX greatly reduced, membranous or fused to base of tergum X ( Fig. 3AView Figure 3). Tergum X subtriangular in lateral and dorsal views, bent ventrad, tapering to apex ( Figs. 3A, 3BView Figure 3); laterally with a mesal triangular dorsal projection on the basal third, apex subacute ( Fig. 3AView Figure 3); in dorsal view strongly tapering to apex from apical half, apex rounded ( Fig. 3BView Figure 3). Intermediate appendages sclerotized, very elongate, base large, trapezoidal, horn-shaped, between 4-5 times longer than preanal appendages, with a hookshaped mark ventrobasally; both slightly turned ventrad and crossing each other over the apical half of the tergum X ( Figs. 3A, 3BView Figure 3). Preanal appendages moderately elongate, club-shaped, covered with small setae; apex rounded ( Figs. 3A, 3BView Figure 3). Inferior appendages elongate, linear, flattened on mesal surface; first articles, laterally, approximately 2 times as long as wide, each ventrally with a row of large spine-like setae on inner margins, setae decreasing in size to base (asymmetric in right and left sides); second article shorter than first (less than half length), base narrower than apex of first article, slightly constricted mesally; apex rounded with prominent pad of short, stiff apicomesal setae ( Figs. 3A, 3CView Figure 3). Phallobase tubular, moderately elongate, with slight curvature near apex; endotheca with a large sclerotized spinous plate, tongue-like, resembling a molluscan radula ( Fig. 3DView Figure 3).

Holotype male: BRAZIL: Rio de Janeiro: Rio Bonito, Lavras, Rio Bacaxá , acima do Poço das Andorinhas, 22°39’40.4”S, 42°36’04.4”W, 22.x. 2017, 267 m, LL Dumas & JL Nessimian leg. ( DZRJ).GoogleMaps 

Paratypes: BRAZIL: Rio de Janeiro: same data as holotype, 3 males, 2 females ( DZRJ).

Distribution: Brazil (RJ).

Etymology: The specific epithet of this species comes from the Latin word cornuta  (horn), in allusion to the horn-shaped intermediate appendages.