Alterosa polyacinata, Barcelos-Silva, Patrik, Dumas, Leandro Lourenço & Pes, Ana Maria, 2015

Barcelos-Silva, Patrik, Dumas, Leandro Lourenço & Pes, Ana Maria, 2015, A new species of Alterosa Blahnik (Trichoptera: Philopotamidae: Philopotaminae) from Espírito Santo State, southeastern Brazil, Zootaxa 3931 (4), pp. 596-599 : 596-598

Alterosa polyacinata sp. nov.

Fig. 1

Diagnosis. Alterosa polyacinata sp. nov. is similar to Alterosa caparaonensis Blahnik 2005 and Alterosa ruschii Dumas & Nessimian 2013 , resembling these species in having highly modified, basally branched intermediates appendages, each heavily armed with coarse setae. Additionally, the basolateral projection on tergum X and the structure and lack of spines in the phallus are also similar. The new species can be distinguished from the others by the presence of a triangular dorsal projection on tergum X and by the structure of the mesal branches of the intermediate appendages, which are divided into superior and inferior arms, whereas in A. caparoenensis and in A. ruschii they are not divided.

Description. Adult male. Length of each forewing 5.5 mm (n=1). Color (in alcohol) brownish; legs, palps, and antennae pale brown, wings brownish-yellow.

Male genitalia. Tergum VIII with posteromesal margin slightly emarginate. Sternum IX with anterolateral margin strongly rounded, extending from dorsum; posteroventral margin greatly produced, forming broad expansion, subtruncate at apex ( Fig. 1 A). Tergum IX fused to base of tergum X. Tergum X, in dorsal view, broad at base, abruptly narrowed at apical second third; with mesal projection over base of tergum ( Fig. 1 D); projection triangular and broadest apically, with seven irregular stout spines, five apically and two subapically positioned, and one tiny apicomesal spine ( Figs. 1 C, 1D); basolaterally with scrabous cuticle broadly projecting ventrolaterad, bearing numerous long spine-like setae ventrolaterally ( Fig. 1 C); apex sensillate, rounded, moderately enlarged in lateral view ( Figs. 1 A, 1C). Intermediate appendages sclerotized, paired, moderately elongate, length subequal to preanal appendages, branched basally ( Figs. 1 A, 1B), both mesal and lateral branches of appendages covered with coarse setae; mesal branches each forked subbasally, its superior arm finger-like, slightly curved outward as viewed dorsally, its inferior arm capitate; lateral branches clavate ( Figs. 1 A, 1B,). Preanal appendages setose, slender, moderately elongate, not greatly modified, slightly enlarged near mid length; apex with few short, spine-like setae ( Figs. 1 A, 1B). Inferior appendages setose, elongate, linear, flattened on mesal surface ( Figs. 1 A, 1E); first article, in lateral view, narrow, about three times longer than wide, slightly larger at base; second article shorter than first, its apex rounded, slightly enlarged with small pad of short, stiff apicomesal setae ( Figs. 1 A, 1E). Phallobase tubular, elongate, narrow, weakly curved at midlength; endotheca without evident spines or phallotremal sclerites ( Figs. 1 F, 1G).

Holotype male. BRAZIL, Espírito Santo: Fundão (Hotel Fazenda Monte Sião, 19°56'02.0''S 40°24'45.0''W), 02.xii.2010, E.A. Raimundi, F.F. Salles, F.C. Massariol, P. Barcelos-Silva, Y.S. Feitosa legs.; in alcohol ( DZRJ).

Etymology. The composite epithet of the specific name, polyacinata , is a combination of the Greek prefix πολύ- or poly- and Greek adjective ᾄκαινατος, -α, -ου or acinatus, -a, - um, which means "many spined." This name refers to the presence of seven stout spines on the apicomesal projection of tergum X and to the many coarse, spine-like setae on intermediate appendages and on the basal ventrolateral projections of tergum X.

Habitat. The specimen described here was collected in a narrow stream with dense vegetation cover within a small remaining of Atlantic Forest. The little stream has a weak water flow with stony bottom and many leaves deposited.

Comments. Despite the fact that we have observed only a single specimen of the new species, we feel confident to describe it as new for science based on its numerous, dramatic diagnostic characters. Alterosa polyacinata sp. nov. differs from all other species of Alterosa in the dorsal triangular projection of tergum X, the unique structure of the intermediate appendages with mesal branches bearing dorsal and ventral arms, and the pair of basal ventrolateral projections of tergum X with numerous long spine-like setae on their ventral margins.

In order to include this species in the identification key provided by Dumas et al. (2013) we propose here an addendum to it, with some modifications to couplet 18, where Alterosa polyacinata sp. nov. would be included.

18. Intermediate appendages each with lateral branch greatly enlarged, lobe-like or capitate; endotheca without spines .. ...................................................................................................................................................................................18’

- Intermediate appendages each with lateral branch not or only moderately enlarged, rod-like; endotheca with tracks of small spines.............................................................................................................................................................19

18’ Tergum X with apicodorsal crest-like Y-shaped expansion; with small, cylindrical, ventrolateral projection on each side basally, and digitate protuberance covered by coarse setae; preanal appendages short, not surpassing lateral branches of intermediate appendages; mesal branches of intermediate appendages simple, not branched (see figs. 11A, 11B in the key of Dumas & Nessimian 2013)........................................... Alterosa ruschii Dumas & Nessimian

- Tergum X forming mesodorsal triangular projection over base of tergum; with large, flattened, subquadrangular, ventrolateral projection on each side basally; preanal appendages long, almost same length as lateral branches of intermediate appendages; mesal branch of each intermediate appendage forked, with superior and inferior arms ( Figs. 1 A, 1B) ................................................................ Alterosa polyacinata sp. nov. Barcelos-Silva, Dumas & Pes

Figures

FIGURE 1. Alterosa polyacinata sp. nov., male genitalia. A, segments IX and X and their appendages, left lateral; B, intermediate and lateral appendages (setae omitted), left lateral; C, tergum X, left lateral; D, segments IX and X and their appendages, dorsal (setae of left intermediate appendage omitted); E, left inferior appendage, ventral; F, phallus, dorsal; G, phallus, left lateral. Abbreviations: inf. app. — inferior appendage; int. app. — intermediate appendage; pr. app. — preanal appendage; phb—phallobase; entc—endotheca.