Rhyacophila parvicauda, Kawase, 2024

Kawase, Naoki, 2024, Redescription of Rhyacophila clemens Tsuda 1940 (Trichoptera, Rhyacophilidae), with descriptions of five new, allied species from Japan, Zootaxa 5447 (1), pp. 55-76 : 69-71

publication ID	https://doi.org/ 10.11646/zootaxa.5447.1.3
publication LSID	lsid:zoobank.org:pub:3A9842EC-F3D2-4839-9731-AA79A27B25CB
DOI	https://doi.org/10.5281/zenodo.11119201
persistent identifier	https://treatment.plazi.org/id/385587AA-F738-1175-FF4C-C443FC9CA705
treatment provided by	Plazi
scientific name	Rhyacophila parvicauda
status	sp. nov.

Treatment

Rhyacophila parvicauda sp. nov.

( Figs 6A–6H View FIGURE 6 , 9D View FIGURE 9 )

Diagnosis. The male of R. parvicauda sp. nov. is similar to those of R. inazui sp. nov. and R angulicauda sp. nov. in having a U-shaped apical hinged process of segment X in ventral view, but can be distinguished from the latter two by the shape of the apicodorsal lobe of segment IX given in the diagnosis for R. inazui sp. nov. Additionally, the male genitalia of this species are unique among this species group in having rows of dense spine-like setae along the mesodorsal margin of the apical segment of each inferior appendage ( Figs 6A, 6C View FIGURE 6 ). Moreover, the apical hinged process of this species is clearly shorter than the other two species, only 1/2 as long as the horizontal part of segment X ( Fig. 6A View FIGURE 6 ), but those of the other two species are about as long as the horizontal part ( Figs 4C View FIGURE 4 , 5A View FIGURE 5 ). Regarding the female, R. parvicauda sp. nov. is similar to R. furcicauda sp. nov. in having many brown thick setae on the lateral surface of segment VIII ( Fig. 6E View FIGURE 6 ), but can be distinguished from the latter by the shape of ventral ridges: In P. parvicauda sp. nov., a ventral ridge of segment VIII is visible posteriorly from the side (arrow in Fig. 6E View FIGURE 6 ), but in P. furcicauda sp. nov., the ventral ridge is invisible in lateral view ( Fig. 7G View FIGURE 7 ).

Adult. Length of each forewing: male 6.4–7.3 mm (mean = 6.7, SD = 0.32, n = 7), female 6.2–6.9 mm (mean = 6.6, n = 2). General morphology and coloration similar to those of R. clemens , but wing venation similar to that of R. inazui sp. nov. ( Fig. 4B View FIGURE 4 ), root of fork I on each forewing clearly longer than that of fork II.

Male genitalia ( Figs 6A–6D View FIGURE 6 ). Segment IX dorsal half longer than ventral half in lateral view ( Fig. 6A View FIGURE 6 ), wide rectangular in dorsal view with small apicodorsal lobe ( Fig. 6C View FIGURE 6 ). Preanal appendages absent. Segment X reverse L-shaped in lateral view, composed of vertical part and horizontal part: vertical part tall in lateral view ( Fig. 6B View FIGURE 6 ); horizontal part thick, oval in dorsal view ( Fig. 6C View FIGURE 6 ); apical hinged process U-shaped in ventral view, with pair of short finger-like lobes parallel, 1/2 as long as horizontal part in lateral view, lobes apically rounded, directed posterodorsad ( Figs 6A–6D View FIGURE 6 ). Anal sclerites composed of two pairs of lobes, each long and rectangular in lateral view, with common internal root ( Figs 6B, 6D View FIGURE 6 ). Apical band well developed, semi-oval in lateral view, broadly surrounding anus and root of anal sclerites ( Figs 6B, 6D View FIGURE 6 ). Tergal band connecting ventral part of apical band to dorsum of phallobase ( Fig. 6B View FIGURE 6 ). Basal segment of each inferior appendage setose, elongate, basal 1/3 narrowest in lateral view ( Fig. 6A View FIGURE 6 ). Apical segment of each inferior appendage subtriangular in lateral view ( Fig. 6A View FIGURE 6 ); mesal surface densely covered by long fine setae, with rows of spine-like setae along dorsal margin ( Fig. 6C View FIGURE 6 ). In phallic apparatus, phallobase short ( Fig. 6B View FIGURE 6 ); aedeagus narrow tube with sclerotized ventral plate ( Fig. 6B View FIGURE 6 ); ventral plate horizontal, tongue-shaped with posterior margin truncate in ventral view ( Fig. 6D View FIGURE 6 ). Parameres absent.

Female genitalia ( Figs 6E–6H View FIGURE 6 ). Segment VIII annular, dorsal margin almost straight or slightly concave in lateral view ( Fig. 6E View FIGURE 6 ); pair of ventral ridges widely separated, posterior ends curved posterodosad, visible in lateral view ( Figs 6E, 6F View FIGURE 6 ); many brown thick setae on lateral surface ( Figs 6E, 6F View FIGURE 6 ); pair of apodemal rods reaching to posterior end of segment VI. Segment IX membranous, with pair of apodemal rods dorsolaterally, extending into abdominal segment VI. Vaginal apparatus simple; posterior process sclerotized, dorsal margin round in lateral view ( Fig. 6G View FIGURE 6 ), apparatus long-oval in ventral view ( Fig. 6H View FIGURE 6 ); processus spermathecae membranous.

Immature stage. Unknown.

Holotype. Male (in alcohol), Mt. Koya-yama primary forests, Oda-cho, Ehime Prefecture, Shikoku, Japan, 33°30’27”N 132°51’39”E, alt. 1100 m, 29.vi.2000, E. Yamamoto ( LBM1410012649 View Materials ). GoogleMaps

Paratypes. Shikoku: Ehime : 2 males, 1 female, same locality as the holotype, 7.vii.2000, E. Yamamoto & M. Doi ( LBM1410012650–1410012652 View Materials ) GoogleMaps ; 1 male, 1 female, same locality as the holotype, 15.vii.2000, E. Yamamoto & M. Doi (SPMN-IS-59791–59795) GoogleMaps ; 3 males, same locality as the holotype, 21.vii.2000, E. Yamamoto & M. Doi (SPMN-IS-59788–59790) GoogleMaps ; 4 males, same locality as the holotype, 29.vii.2000, E. Yamamoto & M. Doi (SPMN-IS-59796–59799) GoogleMaps ; 1 male, Oda-miyama. Oda-cho, 31.v.2001, E. Yamamoto (SPMN-IS-59786); 1 male, same locality, 10.vi.2001, E. Yamamoto (SPMN-IS-59787) GoogleMaps .

Other specimens examined. Shikoku : Ehime: 1 male, same locality as the holotype, 19.viii.2000, E. Yamamoto & M. Doi ( SPMN) GoogleMaps ; 1 female, same locality as the holotype, 20.ix.2000, E. Yamamoto ( SPMN) GoogleMaps . Kochi: 1 male, 1 female, Setogawakeikoku, Tosa-cho, Tosa-gun, 27.v.2004, K. Nio ( SPMN) .

Etymology. The species name “parvicauda ” (= short tail) is a noun in apposition referring to the short, apical, hinged process of segment X.

Distribution and biology. Rhyacophila parvicauda sp. nov. was collected only from a few small headwater streams in a mountain area of Shikoku ( Fig. 9D View FIGURE 9 ). This species tends to be distributed at rather higher altitude than R. inazui and R. vesperalis in the same river systems. Adults of this species were collected from late May to August.

Japanese name. Hime-kuremensu-nagare-tobikera.