Acostatrichia araca Santos & Pes, 2020

Santos, Allan Paulo Moreira, 2020, A review of the Neotropical microcaddisfly genus Acostatrichia Mosely, 1939 with description of a new species from Brazil (Trichoptera: Hydroptilidae: Leucotrichiinae), Zootaxa 4755 (2), pp. 201-230 : 204-205

Acostatrichia araca Santos & Pes new species

Figs. 1–2, 16

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Description. Male. Length: 2.2–2.5 mm (n = 7). General color, in alcohol, light brown. Head modified, in dorsal view with dorsal triangular protuberance and frontal membranous protuberance both covered by setae ( Figs. 1A, 1B). Ocelli 2 ( Fig. 1B). Antenna 19-articulated, scape cylindrical and more than twice as long as wide, inner margin slightly produced posteromesad in dorsal view ( Fig. 1B); pedicel cylindrical; flagellomeres cylindrical, unmodified. Forewings each with costal vein bearing short basal bulla ( Fig. 1C). Abdominal segment VII bearing two short, acute ventromesal processes in tuft of long setae ( Figs. 2A, 2C).

Male genitalia. Segment VIII shorter dorsally than ventrally; in ventral view, posterior margin of sternum produced as transverse bar with acute posterolateral angles ( Fig. 2A); in lateral view, as truncate process ( Fig. 2C); without lateral processes; tergum with row of long setae ( Figs. 2B, 2C). Segment IX mostly within segment VIII, ventrally open, with pair of elongate dorsolateral processes, curved inwards apically in dorsal and ventral views ( Figs. 2A, 2B), gradually upturned in lateral view, each one with short basodorsal spine ( Fig. 2C). Preanal process absent. Inferior appendages paired, short and digitate in ventral view, with few apical and subapical spines but without apical or basal processes ( Fig. 2A). Subgenital plate with transverse process on basal area and round at apex in ventral view ( Fig. 2A); in lateral view, with narrow and downturned apex ( Fig. 2C). Tergum X membranous, posterior margin convex in dorsal view ( Fig. 2B). Phallus tubular basally, bearing midlength complex, with dorsal window and basal loop shorter than basal portion of phallus ( Figs. 2D, 2E); apical portion with long thick internal spine ( Fig. 2E) which is plate-like in dorsal view ( Fig. 2D).

Material examined. HOLOTYPE male: Brazil, Amazonas , base Serra do Aracá, Igarapé da Cobra, 00°52’34”N 63°27’04”W, 02.viii.2009, J.O. da Silva, J.L. Nessimian, U.G. Neiss, light trap ( INPA) ; PARATYPES: same data, 3 males ( DZRJ), 3 males ( INPA).

Remarks. Males of Acostatrichia araca sp. nov. have unusual modifications on the head ( Figs. 1A, 1B), which are not found in other Acostatrichia species. The new species is also peculiar for having only two ocelli, in the genus this condition is found only in A. elvesta . The holotype, which is the unique known specimen of A. elvesta , was not located and we were not able to confirm the presence or absence of modifications on the head of the species, but nothing about these modifications is mentioned in the original description. Related to other morphological features, the new species shares with other Acostatrichia species the presence of a costal bulla on each forewing and the similar general aspect of male genitalia. It is included in the A. plaumanni Species Group due to segment VII bearing two short ventromesal processes; segment IX bearing a pair of long dorsolateral processes; and the inferior appendages being short and not fused mesally. Acostatrichia araca sp. nov. can be distinguished from all other species in the genus by the head with a setose dorsal triangular lobe and a setose frontal lobe ( Fig. 1B); from other Acostatrichia in the A. plaumanni Group, the new species differs by having the dorsolateral processes of segment IX long, curved upwards ( Fig. 2C), and each bearing a basodorsal spine; it also differs by having a strong apical spine on the phallus ( Figs. 2D, 2E), which is plate-like in dorsal view ( Fig. 2D).

Etymology. The species is named in allusion to the type locality, Serra do Aracá, a mountain range in northern Brazil, Barcelos municipality, Amazonas State.

Distribution. Brazil ( Fig. 16).