Hydrobiosella andina, Holzenthal, Ralph W., Blahnik, Roger J. & Rios-Touma, Blanca, 2018

Holzenthal, Ralph W., Blahnik, Roger J. & Rios-Touma, Blanca, 2018, New species and a new genus of Philopotamidae from the Andes of Bolivia and Ecuador (Insecta, Trichoptera), ZooKeys 780, pp. 89-108 : 89

Hydrobiosella andina sp. n. Figs 6, 7

Diagnosis.

This new species is best diagnosed by its venation, elongate and relatively undifferentiated inferior appendages, simple structure of tergum X, and (especially) by the absence of preanal appendages.

Description.

Male. Forewing length 7.8 mm. Spur formula 2:4:4. Overall color fuscous (brownish black), antennae missing (except for scape). Head relatively small, postparietal sclerite moderate in length (shorter than diameter of eye), with 4 dark, stiff bristles subtending eye, eyes without apparent setae between facets. Palps relatively short, segment I very short, globular, segments II and IV short, subequal, II with stout apicomesal bristles, III and V moderate in length, subequal. Hind tibiae distinctly thickened and elongate. Forewing with forks I-V, hind wing with forks I-III and V (IV absent). Forewing with forks I and II slightly subsessile, crossveins s, r-m, and m hyaline and nearly linear, 3A looped to 2A, 2A to 1A, intersecting in proximal half of vein. Hind wing with forks I and II sessile, all 3 anal veins intersecting wing margin.

Genitalia. Sternites (through sternite V) only sparsely setose, V with conspicuous reticulate area surrounding opening of glands, which are well-developed, sternites VI-IX densely setose, with short setae; tergites subquadrate, distinctly narrower than sternites, with paired, desclerotized regions near posterior margins, each with ca. 3 prominent setae (2-5, variation), and also with sparse, minute setae surrounding the desclerotized areas, mostly confined to posterolateral margins. Segment VIII unmodified, only slightly shorter than preceding segments. Segment IX very simple in structure, subquadrate, as viewed laterally, ventral margin ca. twice length of dorsal margin, posteroventral margin slightly projecting; anterior margin nearly linear, with only slightly produced, broadly subtriangular apodemes near middle of segment; venter of segment IX with short suture from anterior margin, dorsum of segment absent (or strap-like and fused to base of tergum X). Tergum X very simple in structure, relatively elongate, narrow, and parallel-sided, apical ¼ abruptly narrowed and similarly parallel-sided, apex rounded, slightly down turned; tergum with numerous minute sensilla, most dense apically and laterally. Preanal appendages absent. Inferior appendages bi-segmented, very elongate, linear, densely setose; basal segment widest near base, narrowing apically; apical segment ca. ¾ length of basal segment, parallel-sided, apex rounded, with dense pad of short, thickened setae on mesal surface. Phallic apparatus very narrow, tubular, much shorter than inferior appendages; phallobase with usual basodorsal expansion, exposed part of endotheca distinctly expanded, apparently elongate (as judged by position of phallotremal sclerite), without spines or ornamentation. Phallotremal sclerite minute, weakly sclerotized.

Female. Unknown.

Holotype.

Male. ECUADOR: Tungurahua: Río Verde, 1600 m, 26.xii.1992, VO Becker (UMSP000136163) (NMNH).

Etymology.

Named for the Andes Mountains, where the first specimen of this genus in the New World was discovered.

Remarks.

The placement of this species in Hydrobiosella is somewhat speculative and is based on what was considered by Ross (1956) a diagnostic feature of the genus: absence of preanal appendages (or the appendages very small or fused basally). Neboiss (1977, 1986) also used the absence or reduction of preanal appendages as a character to diagnose the Australian members of Hydrobiosella . In general, the genus is not very well defined and the individual species are extremely variable. We consider the placement of this new Ecuadorian species to be provisional, pending a revision of the genus. Most of the characters it possesses could be considered ancestral for Philopotaminae, including its general venation: s, r-m, and m crossveins of forewing hyaline and nearly linear; forks I and II of the forewing sessile or slightly subsessile; 3A of the forewing looped to 2A and 2A looped to 1A (intersecting the vein in the basal ½ of the vein, and without any cross veins); hind wing with all three anal veins reaching the wing margin. If the generic placement is correct, this represents the first record of the genus in the Americas.