Rhyacophila huesunensis, new species

Figs 1–5

Male. Body length 6.0 mm (n=3), length of each forewing 7.1 mm, width of each forewing 2.2 mm, length of each antenna 6.2–7.5 mm. Body, antennae, palpi, wings, abdomen and legs dark brown in alcohol.

Male genitalia (Figs 1–5). Segment IX (IX., Figs 1–2) subrectangular, dorsal edge undulate in lateral view, without apicodorsal lobe. Segment X (X., Figs 1–2, 5) triangular in lateral view, with digitiform, short extension bilaterally, mesal lobe with sinuous apical margin in dorsal view. Anal sclerites (a.s., Figs 1, 5) elongate, nearly spindle-shaped, both ends pointed, upper end in touch with segment X in lateral and caudal views; root of anal sclerites long with two proximal claws in lateral view. Tergal strap (t.s., Figs 1, 5) thin, sclerotised extension in lateral view, turban-shaped in caudal view. First segment of each inferior appendage (f.s., Figs 1, 4) much smaller than second segment, pentagonal, with broad ventral margin and acute dorsal proximal angle; second segment divided into two prominent lobes (s.s., Figs 1, 4): upper lobe long, its upper margin curved ventrad subapically, with small subtriangular process on base of sinuous lower margin in lateral view, surface setose; lower lobe (Figs 1, 4) subtriangular with bulge on base of serrate, oblique upper margin, distal end blunt, lower margin straight, proximally curved upward; lower lobe slightly longer than upper lobe in lateral view. Phallotheca (phal., Fig. 3) short, tubular; endotheca (end., Fig. 3) longer, membranous, tubular in lateral view; phallicata (ph., Fig. 3) composed of stout proximal part and narrow, tubular distal part, phallic apparatus without dorsal appendage (d. app.); ventral process (v.p., Fig. 3) with accentuated medial lobe and huge dorsal and ventral spikes directed caudodorsad in lateral view; parameres (par., Fig. 3) ribbon-like and three times as long as segments IX–X when fully everted, distal end subtriangular and densely setose in lateral view.

Female. Unknown.

Holotype: ♂, TAIWAN: Huesun Forest Area, 16 km E of Kuohsing, Nanton County, Taiwan, Republic of China, 24o05’N, 121o00’E, 560 m elevation, by light trapping, 10 November 1996, leg. Tibor Csővári and Csaba Szabóki (gen. prep. No. 124, Ottó Kiss, coll. Mátra Museum).

Paratypes: 2 ♂, TAIWAN: Huesun Forest Area, 16 km E of Kuohsing, Nanton County, Taiwan, Republic of China, 24o05’N, 121o00’E, 560 m elevation, by light trapping, 10 November 1996, leg. Tibor Csővári and Csaba Szabóki (coll. Ottó Kiss).

Differential diagnosis. This species belongs to the Rhyacophila scissa Group of the R. philopotamoides Branch (Schmid 1970) . The male genitalia of this species are similar to those of R. matanyii Kiss 2013 from Taiwan and R. steinmanni Kiss 2013 from Nepal, but differs from them in that:

1. Segment X is triangular in lateral view (not rectangular as in R. matanyii or not subrectangular as in R. steinmanni) composed of short, digitiform extension bilaterally and mesal lobe in dorsal view (absent in R. matanyii and R. steinmanni).

2. The anal sclerites are elongate, nearly spindle-shaped (not bulging as in R. matanyii or not hatchet-shaped as in R. steinmanni).

3. The distal end of phallic parameres is subtriangular in lateral view (not similar to tennis racket as in R. matanyii or not bell-shaped as in R. steinmanni).

4. The tergal strap is turban-shaped (not heart-shaped as in R. matanyii).

5. The distal part of the lower lobe of the second segment of each inferior appendage is subtriangular (not hookshaped as in R. matanyii or not footprint-shaped as in R. steinmanni), a bulge is present on the base of the upper margin of the lower lobe (it is absent in R. matanyii and also in R. steinmanni).

Etymology. Named for the place where the new species was collected.