Metrichia pitu Angrisano & Sganga

Angrisano, Elisa B. & Sganga, Julieta V., 2009, New species of Hydroptilidae (Trichoptera) from Salto Encantado Provincial Park (Misiones province, Argentina), Zootaxa 2162, pp. 57-68 : 60

Metrichia pitu Angrisano & Sganga , new species

Figures 9–12

Male. Forewing length 2.1 mm. Coloration of the body (in alcohol) dark grayish brown. Abdominal sternum VII with a spine. Segment VIII annular, becoming narrower towards the venter, where it is reduced to a thin medial strip ( Fig. 9 ). Sternum IX lengthened, produced, and lightly truncated anteriorly. Tergum IX short, rounded posteriorly, with a lobe that situates above the phallus; apex deeply cleft mesally (the cleft is narrow posteriorly and rounded at the base) ( Figs. 9–11 ). Lateral appendages quadrangular, with the apex concave in lateral view. Cerci short and rounded. Dorsal appendages resembling curved, long spines, shorter than the dorsal lobe of segment IX. Phallus long, reaching segment II; with a pair of robust, strongly pigmented, apical spines; central tubule dark up to half its length ( Fig. 12 ).

Diagnosis. Based on the structure of the male genitalia this species seems to be more closely related to a group of species from Central America, than with the species known regionally, especially with M. similis ( Flint 1968) from Dominica, whose males are characterized by having the segment X sclerotized and with a V-shaped cleft at the apex (absent in other known species of the genus); segment IX oval anteriorly, and lateral appendages, that are longer than the dorsal lobe, with a deep V-shaped cleft at the apex.

This is the 2nd species of Metrichia described from Salto Encantado Provincial Park. Previously M. cuniapiru Angrisano 2005 (in Angrisano & Sganga 2005) was described. The latter differentiates from the new one by: tergum X membranous, lateral appendages wide, short, and relatively truncated at the apex, segment IX oval anteriorly, phallus without dark, conspicuous spines at the apex.

Holotype male. Argentina: Misiones: Departamento de Cainguás , Parque Provincial Salto Encantado, 24–30.x. 2004.

Paratypes. Argentina: Misiones: Departamento de Cainguás , Parque Provincial Salto Encantado, 24–30.x. 2004, 6 males.

Etymology. From indigenous Guaraní pytû, dark, referring to the coloration of the specimens.

Figures

FIGURES 1 – 12. Figs. 1 – 8, Alisotrichia cainguas, n. sp.: 1: Head, dorsal view. 2: Maxillary palp. Figs. 3 – 5, abdominal segment VIII: 3: ventral. 4: lateral. 5: abdominal segments VIII – X, dorsal. Figs. 6 – 7: abdominal segment IX: 6: lateral. 7: ventral. 8: phallus. Figs. 9 – 12, Metrichia pitu, n. sp., male genitalia: 9: lateral. 10: ventral. 11: dorsal. 12: phallus.