Homoplectra albomarginata
Creators: name: Nozaki, Takao
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Trichoptera
Hydropsychidae
Homoplectra
Homoplectra albomarginata

description: Homoplectra albomarginata (Ulmer 1907)
(Figs 2A–2C, 4, 5, 12A–12C, 13)
Diplectrona albomarginata Ulmer 1907, p. 74, holotype female, Museum of Natural Sciences of Belgium, Brussels.
Diplectrona japonica nec Banks 1906: Ulmer 1907, pp 72–74, pl. 4 fig. 19, male; Kobayashi 1968, p. 3; Hatta and Nozaki 1991, p. 200. Misidentifications.
Diplectrona sp. 2: Torii and Hattori 2006, pp 37–38.
Diplectroninae Gen. sp.: Morita 2009, pp 6–7; Kawase and Morita 2014, p. 5.
Diplectroninae Gen. japonica Complex: Nozaki et al. 2014, p. 61; Nojima 2017, p. 119 (in part).
Diplectrona japonica Species Complex: Watanabe 2021, pp 41–43, mating behavior.
Homoplectra albomarginata: Nozaki 2021, pp 254–256, figs 6A–6E, female, changed combination.
Homoplectra japonica Species Complex: Higuchi 2024, p. 19.
Diagnosis. Adults of this species and H. japonica are similar to each other in general morphology and coloration, but these species can be distinguished from each other by the length of the antennal scape: Each scape of this species is apparently longer than wide in this species (Figs 2B, 2C), but as long as wide in H. japonica (Figs 1C, 1E). The male and female of this species are similar to those of Homoplectra inazui sp. nov. in having long antennal scapes (Figs 2B, 2C); but are easily distinguishable from the latter by the following characters: In the male, the subapicomesal surface of each inferior appendage bears a small process with a few apical spine-like setae in H. albomarginata (Fig. 4A), but many spine-like setae arise directly from the apicomesal surface in H. inazui sp. nov. (Fig. 10A); in the female, tergum IX is broadly sclerotized ventrally in H. albomarginata (marked with an arrow in Fig. 4H) but semi-membranous in H. inazui sp. nov. (Fig. 10H). Furthermore, the vaginal apparatus bears an eye-glasses-shaped sclerite posterodorsally in this species (Fig. 4H) but lacks such a sclerite in H. inazui.
The larva is distinguishable from known Japanese larvae by the shape of anterior margin of the frontoclypeal apotome given in the diagnosis for H. japonica. Furthermore, abdominal segment VII is lacking the subventral tufts of gills in this species but bears them in the known Japanese species (Nozaki 2019; Kochi et al. 2023).
Description
Adult (Figs 2A–2C). General morphology and coloration similar to those of H. japonica, but scape of each antenna apparently longer than wide (Figs 2B, 2C). Yellow markings on female wings occasionally indistinct or lacking (Fig. 2A 3). Holotype female lacking distinct markings of wings (Nozaki 2021, fig. 6A). Forewings each 7.0– 9.5 mm long in male (n = 10), 8.5–11.5 mm long in female (n = 11), 10.3 mm long in female holotype. Antennae shorter than forewings; scape approximately 2 times longer than wide, with long hair-like setae dorsally, each pedicel about 1/4 length of its scape (Figs 2B, 2C).
Male genitalia (Figs 4A–4F). Ventrolateral side of synsclerotized segment IX triangular anteriorly in lateral aspect (Fig. 4A); posteroventral lobe triangular in ventral aspect (Fig. 4C); dorsal part of segment IX semicircular in dorsal aspect (Fig. 4B), broadly fused with segment X laterally (Fig. 4A). Segment X tapering to acute apex and bilobed posteriorly in dorsal aspect, pair of posterolateral setose areas protruding posterad (Figs 4A, 4B); ventral part membranous, with pair of posterior processes (p.p.X) thick and sword-like (Figs 4A, 4D) with base of each process fused with lateral strip (l.s.) of genital chamber (Figs 4A, 4D). Genital chamber with pair of lateral strips (l.s.) strongly sclerotized (Figs 4A, 4D), rarely with pair of tiny inner processes (i.p.) near base of phallotheca (Fig. 4D). Inferior appendages long and finger-like, slightly bent upward at 2/5 from base, truncate apically in lateral aspect (Fig. 4A); each apex weakly depressed mesally, with short process bearing few tiny spine-like setae subapicomesally (Figs 4A inset, 4C). Basal plate of inferior appendages sclerotized, long rectangular in ventral aspect (Fig. 4C) and fused anteriorly with anteroventral edge of phallotheca. Phallotheca evenly curved ventrad (Figs 4A, 4E 1, 4E 2); with dorsal process (d.p.p.) and pairs of lateral and ventral processes (l.p.p. and v.p.p.), each apex acute, length of each process variable (Figs 4E 1, 4E 2); with thick ventral spine (v.s.p.) sub-basally (Figs 4C, 4E 1, 4E 2). Aedeagus (Fig. 4F) evenly curved ventrad; stem with lateral flanges, half-pipe-like; head approximately 1/10 of stem.
Female genitalia (Figs 4G–4J). Lateral lobes of sternum VIII (l.l.) widely separated from each other ventrally (Fig. 4I). Segment IX obliquely rectangular in lateral aspect (Fig. 4G), trapezoidal in dorsal aspect (Fig. 3H); ventral surface of tergum broadly sclerotized, wing-like in dorsal aspect (marked with an arrow in Fig. 4H); mesal lobe (m.l.IX) weakly sclerotized, oval in lateral aspect (Fig. 4G), each forming large pocket-like crevice between it and segment IX in ventral aspect (marked with an arrow and asterisk in Fig. 4I); pair of sclerotized ribs (s.r.) forming pair of short round plate-like lobes on vulvar scale basoventrally (Fig. 4I), but shape of lobes variable (Figs 4J1–4J3). Vulvar scale (v.s.) large, tongue-like, its apical margin with small median protrusion (Fig. 4I); with pair of deep holes basolaterally. Segment X setose, tall and longitudinally shot in lateral aspect (Fig. 4G). Vaginal apparatus (v.a.) long pentagonal in dorsal aspect (Fig. 4H), tapering to duct of bursa copulatrix; with eye-glasses-shaped sclerite posterodorsally, with pair of longitudinal ridges dorsally, and with dark arched marking anterodorsally, partially surrounding opening of duct of spermatheca (d.s.).
Variations of male and female genitalia (Fig. 5). As described above, some of females collected from Moroka, Sakauchi-sakamoto, Ibigawa-cho, Gifu, have genitalia, especially a pair of basoventral lobes on the vulvar scale, very similar to those of the holotype female (Fig. 4I; Nozaki 2021, fig. 6C) although the shape is variable even at the same site (Figs 4J1–4J3). In males in this population, the lengths of the processes of the phallotheca are also variable (Figs 4E 1, 4E 2). Furthermore, males collected nearby, in the same town, where females have their genitalia indistinguishable to those of the Moroka population, each bear a pair of distinct inner processes of the genital chamber, and the length of these processes is variable (Figs 5A 1, 5A 2). In other areas, different forms of the male genitalia are found not only in the above-mentioned characters but also in the shapes of segment X, the posteroventral lobe of segment IX, inferior appendages, the head of the aedeagus, and the presence or absence of the ventral spine of the phallotheca. Females collected with these males often have genitalia slightly different from those of the Moroka population, especially in the shape of the vulvar scale and vaginal apparatus. Some examples of these male and female variations are shown in Figs 5B–5F; although these forms are often variable even in the same locality.
Final instar larva (Figs 12A, 12C). Head 1.3–1.8 mm wide (n = 8), slightly longer than wide (Fig. 12A); frontoclypeal apotome asymmetrical in dorsal aspect, anterior margin evenly convex mesally, concave laterally, left side recessed, secondary setae acicular (Fig. 12B, inset); posterior angle 82°–85°, maximum width 0.9–1.2 mm. Meso- and metathorax and abdominal segments bearing gills, with one pair of ventral tufts of gills on mesothorax and abdominal segment VII, with two pairs of ventral tufts of gills on metathorax and each of abdominal segments I to VI, with 1–3 lateral conical gills on each of abdominal segments III to VII.
Pupa (Fig. 12C). Body length 9.5–12 mm (n = 5). Anal processes (Fig. 12C) sclerotized, not bifurcate, ventral surfaces covered by tiny spines, with apices acute and directed dorsad. Other characters similar to those of H. japonica (Figs 11C–11E).
Specimens examined. JAPAN: HONSHU: Niigata: 1 female, Mt. Amakazari, Itoigawa-shi, 26.vi.1955, K. Baba (KPM); 1 female, Mushi-gawa (alt. 170 m), Oyachi, Itoigawa-shi, 27.v.1995, T. Hattori (SPMN); 1 female, Fudo-no-taki (alt. 300 m), Oyachi, Itoigawa-shi, 27.v.1995, T. Hattroi (SPMN). Toyama: 1 male, Nashitani-gawa, Ainokura, Nanto-shi, 17.vi.2018, Y. Higuchi. Ishikawa: 3 male, 3 females, Hodatsushimizu-cho, 2–26.v.1990, I. Togashi (KT); 1 male, Sannomiya, Tsurugi, Hakusan-shi, 18.iv.1984, I. Togashi (KT); 1 male, Sunagozen, Hakusan-shi, 25.v.1980, I. Togashi (KT); 1 male, Odani, Chugu, Hakusan-shi, 28.v.2016, Y. Higuchi; 2 males, Ushikubi-gawa, Shiramine, Hakusan-shi, 8.vi.2021, Y. Higuchi; 1 female, small stream, Ushikubi-gawa, Shiramine, Hakusan-shi, 2.vii.2023, Y. Higuchi; 1 male, 2 females, Ohirasawa, Kanazawa-shi, v.1982, M. Eguchi (KT); 1 male, Nabetani, Nomi-shi, 29.iv.1990, Y. Sugie (KT); 20 males, same locality, 1.v–5.vi.1993, Y. Sugie (KT); 2 males, Dainichi R., Maruyama, Komatsu-shi, 17.vi.1982, K. Tanida (KT). Fukui: 2 males, 1 female, Kitadanicho-obara, alt. 1400 m, Katsuyama-shi, 27.vii.2003, K. Inazu; 1 male, Nyu, Mihama-cho, 21.v.2001, N. Kawase (NK); 2 males, 1 female, Misaka-dani, Oono-shi, 10.vi.2006, T. Torii (SPMN); 1 male, Shimoshinjo, Sabae-shi, 6.v.1986, H. Nishida (KT); 1 male, Nokatani (alt. 310m), Notaoi, Natasho, Ohi-machi, 25.iv.2010, T. Hattori (SPMN). Nagano: 1 male, Aoni-sawa (alt. ca. 850 m), Hakuba-mura, 11.vi.1995, T. Hattori (SPMN); 3 males, 2 females, Kamikochi, Azumi, Matsumotoshi, alt. 1510 m, 4.vii.2010, K. Tojo (SUMNS); 1 male, 1 female, nr. Mizuki-sawa, Ogiso, Kiso-mura, alt. 1300 m, 13.vi.2012, T. Nozaki; 1 male, Chigono, Fukushima, Kiso-machi, 31.v.1993, N. Kuhara (KuN); 2 females, Komanoyu, Fukushima, Kiso-machi, 31.v.1993, N. Kuhara (KuN). Gifu: 5 males, Ozu, Ibigawa-cho, 14–16.v.2001, N. Kawase (NK); 10 males, 1 female, same locality, 13.v.2002, N. Kawase; 31 males, 4 female, 5 pupae, 2 prepupae, 1 larva, Hin-dani, Ibi-gawa (alt. 400 m), Ibigawa-cho, 3–4.v.1996, T. Hattori (SPMN); 4 males, 1 female, 1 larva, Nishimaenotani, Tsurumi, Ibigawa-cho, 10.iv–1.vi.2002, N. Kawase (NK); 5 males, 6 females, Moroka, Sakauchi-Sakamoto, Ibigawa-cho, 20.iv–8.v.2023, N. Kawase, Malaise trap (KPM); 2 males, 1 female, same data except collecting date 8.v–18.v.2023 (NK); 10 males, 8 females, same data except collecting date 18.v–12.vi.2023 (KPM); 1 female, same data except collecting date 12.vi–29.vi.2023 (NK); 3 males, 1 female, same locality, 9.v.2024, N. Kawase; 1 male, Meiho-kera, Gujo-shi, 2.v.1992, T. Hattori (SPMN); 2 females, 1 female, Iwai-machi (alt. 1220 m), Takayama-shi, 9.vi.2011, T. Hattori (SPMN); 1 female, Kokufu, Takayama-shi, 9.vi.2019, H. Suzuki; 1 female, Amou, Kawai-cho, Hida-shi, 20.vi.2020, N. Kawase (NK); 3 males, 1 female, Fudo-daki, Tsukechi-cho, Nakatsugawa-shi, 21.v.1996, T. Nozaki (KPM); 1 male, 1 female, Shinden, Fukuoka, Nakatsugawa-shi, 21.v.1996, T. Nozaki (KPM). Shizuoka: 2 males, Nishigochi-gawa, Umegashima, Aoi-ku, Shizuoka-shi, 1.v.2010, T. Torii (TT); 1 male, 1 female, Nyujima, Aoi-ku, Shizuoka-shi, 5.v.1997, T. Hattori (SPMN); 3 males, 3 females, same locality, 9.v.1999, T. Hattori (SPMN); 1 male, same locality, 9.v.2006, T. Torii (TT); 1 female, Hirano, Aoi-ku, Shizuoka-shi, 11.v.1996, T. Hattori (SPMN); 1 male, Yunno, Shizuoka-shi, 29.iv.1989, T. Hattori (SPMN); 1 male, Dainichi, Ikawa, Aoi-ku, Shizuoka-shi, 21.v.2003, T. Hattori (SPMN); 1 male, Uchimaki-gawa, Shizuoka-shi, 1.v.2001, T. Hattori (SPMN); 1 male, Sumata-kyo, Senzu, Kawanehon-cho, 4.vi.2007, T. Hattori (SPMN); 1 male, 4 females, same locality, 4.v.2010, T. Torii (TT); 1 male, Utoge-no-taki, Setonoya, Fujieda-shi, 2.viii.2001, T. Torii (TT); 1 male, same locality, 18.v.2003, T. Torii (TT); 2 females, Yamame-dani, Setonoya, Fujieda-shi, 8.v.2004, T. Torii (TT); 3 males, 1 female, Ookaya-gawa, Kamiooka, Shimada-shi, 26.iv.2002, T. Torii (TT). Aichi: 2 males, 1 female, 1 pupa, 8 larvae, Mennoki-toge, Tsugu, Shitara-cho, 27.v.1990, T. Nozaki (KPM); 3 males, same locality, 14.v.1991, T. Nozaki (KPM). Mie: 1 male, Mt. Nonobori, Kameyama-shi, 8.v.1994, H. Morita (KT); 7 males, 2 females, Miyazuma-kyo, Suizawa-cho, Yokkaichi-shi, 26.v.2009, H. Morita; 12 males, 1 female, Yunoyama, Komono-cho, 19.v.2005, H. Morita; 1 male, Kawachi-dani (alt. 300 m), Yamaguchi, Fujiwara-cho, Inabe-shi, 4.vi.2006, H. Morita, T. Nozaki & T. Hattori (SPMN). Shiga: 18 males, 1 female, Ibuki, Maibara-shi, 1.v.1985, H. Nishimoto (KT); 33 males, 22 females, Ojigahata, alt. 600 m, Taga-cho, Shiga, 10.v–8.vi.2008, H. Morita; 1 male, Ohara, Yogo-cho, Nagahama-shi, 17.v.2010, N. Kawase (NK); 4 males, 1 female, Nakanokawachi, Yogo-cho, Nagahama-shi, 17.v–26.vi.2010, N. Kawase (NK); 9 males, Shiratani, Makino-cho, Takashima-shi, 17.v.2014, N. Kawase; 3 males, 1 male pupa, Akebibara, Tsuchiyama-cho, Koka-shi, 15.v.1989, T. Nozaki (KPM); 5 males, 1 female, Okawara, Tsuchiyama-cho, Koka-shi, 14–30.v.2008, N. Kawase (NK); 2 males, 1 female, Buhei-toge, Okawara, Tsuchiyama-cho, Koka-shi, 13.v.2008, N. Kawase (NK); 2 males, Shirokura-dani, Okawara, Tsuchiyama-cho, Koka-shi, 17.v.2005, N. Kawase (NK); 1 male, 1 female, same locality, 30.iv.2007, N. Kawase (NK); 40 males, 45 females, Yuzurio, Eigenji-cho, Higashiomi-shi, 12–31.v.2009, N. Kawase (NK); 1 male, same locality, 12.v.2009, N. Kawase (NK); 4 males, Oishitomikawa-cho, Otsu-shi, 22.iv–16.v.2024, N. Kawase (NK). Hyogo: 3males, 1 female, Soryu-no-taki, Santocho-kawakami, Asago-shi, 15.v.2015, K. Inazu (KI); 1 male, 2 females, Hyono-senrindo, alt. 911 m, Unawa, Sekimiya-cho, Yabu-shi, 2.vi.2007, K. Inazu (KI); 2 males, 1 female, same locality, 30.v.2022, K. Inazu; 1 male, seep, alt 965 m, Oyacho-yokoiki, Yabu-shi, 18.v.2023, K. Inazu (KI); 2 females, same locality, 28.vi.2023, K. Inazu (KI); 2 males, 2 females, Ichinomiyacho-sencho, Shiso-shi, alt. 800–900 m, 6.vi.2016, K. Inazu (1 male, 1 female: KI); 3 males, 1 female, Arinocho-karato, Kita-ku, Kobe-shi, 12.v.2020, S. Watanabe (MNHA). Okayama: 1 male, Ogaya, Nishiawakura-son, 28.v.2017, K. Nojima (KN); 9 males, 2 females, Ombara, Kamisaibara, Kagamino-cho, 23.v.2021, K. Nojima (6 males, 1 female: KN).
Distribution. Honshu (central to western).
Biology. Larvae of this species were collected from small spring flows or seeps in mountain areas. Adults were active in the daytime of late spring to early summer, and Watanabe (2021) reported a diurnal mating behavior.
Japanese name. Nagae-kimadara-shima-tobikera.
Remarks. Descriptions of male and female genitalia above are based on 17 males and 15 females collected using a Malaise trap in Moroka, Sakauchi-sakamoto, Ibigawa-cho, Gifu Prefecture. These females have genitalia similar to those of the holotype female (Nozaki 2021, fig. 6C). Ulmer (1907) described this species as a member of the genus Diplectrona based on a female specimen, and Nozaki (2021) transferred it to the genus Homoplectra based on the examination of photographs of the holotype.
Nozaki (2021) mistakenly wrote that the holotype female was collected from “an unknown locality in Gifu, central Honshu”; but in fact, Ulmer (1907) did not mention the precise name of the type locality other than “ Japan.” Although the type locality of this species is not known, females which have similar genital morphology as those of the holotype were found in specimens collected from western Gifu and adjacent areas in central Honshu in this study (Fig. 4I and Nozaki 2021, fig. 6E).
In addition, Ulmer (1907) recorded males collected from Gifu as Diplectrona japonica [= H. japonica]; however, the male of H. japonica described above does not have a pair of long spine-like processes arising from the genital chamber as described and illustrated by Ulmer (1907, figs 114–115). According to Ulmer’s description, his male bears a tooth-like projection (eine zahnartige Erhebung) on the subapicomesal face of each inferior appendage. These characters suggest that his specimen must belong to H. albomarginata.
The male and female genitalia of H. albomarginata are very variable (Figs 4, 5). Although I treat them as individual and/or geographic variations in the single species H. albomariginata, further study with molecular data is needed to confirm their identity and phylogenetic relationships.
description: Published as part of Nozaki, Takao, 2025, Redescriptions of Homoplectra japonica (Banks 1906) and H. albomarginata (Ulmer 1907) (Trichoptera, Hydropsychidae), with descriptions of five new similar species from Japan, pp. 303-328 in Zootaxa 5566 (2) on pages 309-314, DOI: 10.11646/zootaxa.5566.2.4, http://zenodo.org/record/14702954