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

description: Homoplectra japonica (Banks 1906)
(Figs 1A–1E, 3, 11A–11E, 13)
Arctopsyche japonica Banks 1906, pp 111, 113, color pattern of male forewing.
Diplectrona japonica (Banks): Ulmer 1907, pp 72–74, figs 114, 115, changed combination.
Diplectrona japonica (Banks 1906): Gyotoku & Nozaki 1991, pp 74–75, pl. 9, male (photo).
Homoplectra japonica (Banks 1906): Nozaki 2021, pp 254, 255, male, changed combination.
Diagnosis. The male of this species is very similar to that of Homoplectra flagelliformis sp. nov. but is distinguishable from the latter by the characters given in the diagnosis for that species.
The female is easily distinguishable from those of other Japanese species by the shape of a pair of large round basoventral lobes on the vulvar scale (Figs 3H, 3I). Furthermore, female segment IX of this species has a pair of unique ventrolateral sclerotized plates that are oblong in dorsal and lateral aspects (marked with arrows in Figs 3G, 3I).
The larva is distinguishable from known Japanese larvae by the shape of anterior margin of the frontoclypeal apotome:Asymmetrical and sinuous in this species (Figs 11A, 11B); but symmetrical in Homoplectra crassa Nozaki 2019 and Homoplectra tohokuensis Nozaki 2019 (Nozaki 2019, figs 7A–7L, 8), bearing a small median triangular process in Homoplectra gracilis Nozaki 2019 (Kochi et al. 2023, figs 3g, 3i), and asymmetrical and evenly convex mesally in H. albomarginata (Figs 12A, 12B).
Description
Adult (Figs 1A–1E). Head and thorax mostly dark brown dorsally, but dorsal setal warts of head, pro-, and mesonota with golden hair; face light brown in male, dark brown in female; compound eyes slightly larger in male than those in female (Figs 1C, 1E). Legs mostly pale yellow to light brown; but middle and hind coxae of male and all coxae of female dark brown. Abdomen mostly dark brown, but pleural membranes pale yellow. Antennae light brown in male, dark brown in female, shorter than forewings; scapes thick, approximately as long as wide, with long hair-like setae dorsally (Figs 1C, 1E); pedicels shorter than scapes, basal segment of each flagellum longer than scape (Figs 1C, 1E). Wing venation similar in male and female. Forewings each 6.5–9.5 mm long in male (n = 11), 9.0– 11.5 mm long in female (n = 10), 6.5 mm in male lectotype; yellow, with broad dark stripes (Fig. 1A); hind wings pale yellow with dark stripes (Fig. 1A); venation of both wings as in Figure 1B: with forks I, II, III, IV, and V in forewings and I, II, III, and V in hind wings; discoidal and medial cells closed in both wings. Tibial spurs 2-4-4. Abdominal sternum V with pair of finger-like processes associated with scent glands near anterolateral margins, slightly shorter than sternum (Fig. 1D).
Male genitalia (Figs 3A–3E). Ventrolateral sides of synsclerotized segment IX (IX) subtriangular in lateral aspect (Fig. 3A); posteroventral lobe (p.l.) trapezoidal in ventral aspect, with shallow median concavity (Fig. 3C); dorsal part of segment IX triangular with round and setose apex in dorsal aspect (Fig. 3B), fused with segment X (X) laterally (Fig. 3A). Segment X bilobed in dorsal aspect (Fig. 3B), with pair of large posterolateral setose areas (Figs 3A, 3B); each ventrolateral margin sclerotized, recessed into segment IX (Fig. 3A). Inferior appendages (i.a.) each without distal segment, long and finger-like in lateral aspect, dorsal margin weakly concave at apical 1/ 5 in lateral aspect, extending beyond apex of segment X (Fig. 3A); apex slightly enlarged mesally and truncate, with several short spine-like setae (Figs 3A–3C). Basal plate of inferior appendages (b.p.i.a) sclerotized, subrectangular in ventral aspect (Fig. 3C). Phallotheca with dorsal process (d.p.p.), acicular in dorsal and lateral aspects, weakly curved ventrad (Figs 3D, 3E); with pair of ventral processes (v.p.p), long, approximately same length as dorsal process of phallotheca, each apex acute, curved dorsad and slightly mesad (Figs 3D, 3E). Aedeagus (ae.) arising from membranous endotheca (end.), evenly curved ventrad, with long head approximately 1/4 as long as basal stem (Fig. 3D); stem with lateral flanges, half-pipe-like, narrow at apical 3/4 and near base in dorsal aspect (Fig. 3E), with pair of apical swellings in dorsal and ventral aspects (Figs 3C, 3E).
Female genitalia (Figs 3F–3I). Sternum VIII widely separated into pair of lateral lobes (l.l.) ventrally, each lobe bean-shaped in ventral aspect (Fig. 3H). Segment IX (IX) obliquely rectangular in lateral aspect (Fig. 3F), posterodorsal part trapezoidal in dorsal aspect (Fig. 3G); tergum with pair of ventrolateral sclerotized plates (marked with arrows in Figs 3G, 3I), weakly constricted at mid-length in lateral aspect (Fig. 3I), oblong in dorsal aspect (Fig. 3G); each mesal lobe (m.l.IX) sclerotized, bean-shape in lateral aspect (Figs 3F, 3I), forming large crevice between it and ventrolateral plate in ventral aspect (marked with arrow and asterisk in Fig. 3H); pair of sclerotized ribs (s.r.) forming large round plate-like lobes on vulvar scale (v.s.) basoventrally (Figs 3H, 3I). Vulvar scale large, tongue-like in ventral aspect (Fig. 3H), semimembranous apically. Segment X slender in lateral aspect (Fig. 3F). Vaginal apparatus (v.a.) long-pentagonal in dorsal aspect (Fig. 3G), tapering to duct of bursa copulatrix (d.b.c.); with pair of peanut shape sclerites posterodorsally, with pair of longitudinal ridges dorsally, and with dark arched marking anterodorsally, partially surrounding opening of duct of spermatheca (d.s.).
Final instar larva (Figs 11A, 11B, 11F). Head 1.6 mm wide (n = 1), approximately as long as wide (Fig. 11F, hl, hw); frontoclypeal apotome asymmetrical in dorsal aspect (Fig. 11B inset), maximum width 1.2 mm, posterior angle about 90°, with anterior margin sinuous, left side recessed, very weakly concave in middle, with most secondary setae clavate. Mandibles each with 5 teeth. Pronotum with transverse sulcus on posterior 1/4 (Fig. 11A). 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 subventral tufts of gills on metathorax and each of abdominal segments I to VI, with 1–3 sublateral conical gills on each of abdominal segments III to VII. Secondary setae on thoracic nota and abdominal segments mostly clavate.
Pupa (Figs 11C–11E). Body length 10 mm (n = 1). Mandibles slender, with 3 (right) or 4 (left) apical and subapical teeth, each mandible with stout mesal plate-like projection on apical 1/3. Middle tarsi bearing sparse hair-like setae. Abdominal segments with dorsal hook plates anterior on II to VIII, posterior on III and IV (Figs 11C, 11D). Abdominal segments bearing gills, with one pair of ventral tufts of gills on each of abdominal segments II to VI, with lateral conical gills on each of abdominal segments III to VII. Anal processes sclerotized, ventral surfaces covered by tiny spines; bifurcated, each apex acute, mesal branch longer than outer one (Fig. 11E).
Lectotype: Male (here designated, pinned: MCZ:Ent:11833): labeled “type”, “ Hikosan, Buzen, Japan ”, “Collection N. Banks”, “ Arctopsyche japonica Banks /type”, “Type 11833”, “ Trichoptera: Diplectrona japonica wings from Type/Det. H.H. Ross, 19/ILL. NAT. HIST. SUR (right wings in slide)” (https://mczbase.mcz.harvard. edu/guid/MCZ:Ent:11833; Nozaki 2021, fig. 5).
Specimens examined. JAPAN: HONSHU: Yamaguchi: 1 male, Nankai, Atojifukushimo, Yamaguchi-shi, 17.v.1993, N. Kuhara. KYUSHU: Fukuoka: 1 female, Mt. Hiko-san, Soeda-machi, 31.v.1935, K. Yamauchi (KPM); 11 males, 9 females, same locality, 19.v.1993, N. Kuhara (6 males, 3 females: KuN); 1 male, 1 female, same locality, 9.vi.1994, T. Nozaki (1 male: SPMN); 1 male pupa with larval exuviae, 1 larva, same locality, 22.v.1996, T. Hattori (SPMN); 1 male, Mt. Kosho, Asakura-shi, 18.v.1969, N. Gyotoku (KPM); 1 pupa, 2 pupal remnants with larval exuviae, Dobaru (alt. 200 m), Kokuraminami-ku, Kitakyushu-shi, 17.iv.2004, T. Hattori (SPMN). Oita: 1 male, Shimizubakuen, alt. 450 m, Mori, Kusu-machi, 18.iv.2004, T. Hattori (SPMN).
Distribution. Westernmost Honshu, northern Kyushu.
Biology. Larval and pupal specimens of this species were collected from small streams in hilly and mountainous areas.
Japanese name. Kimadara-shima-tobikera.
Remarks. Banks (1906) described A. japonica from Fukuoka, Kyushu and Gifu, central Honshu as “Hikosan, Buzen [now Fukuoka], Japan, 28 April; also from Gifu ”, but no holotype was designated. Nozaki (2021) transferred this species to the genus Homoplectra based on examination of photographs of a syntype male (MCZ:Ent:11833) collected from Fukuoka and deposited in the Banks collection of MCZ. In this study, I examined photographs of another specimen also deposited in the Banks collection as a syntype (MCZ:Ent:648191) kindly provided Dr. C. W. Farnum (MCZ). Since this specimen had a handwritten label “ Gifu Japan ” (https://mczbase.mcz.harvard.edu/ guid/MCZ:Ent:648191), the record from Gifu in the original description by Banks (1906) must have been based on it. Although I could not examine its genital morphology because of mold covered the abdomen, the length of the scape of left antenna (right antenna missing) was apparently longer than its width. Since the syntype male collected from Fukuoka has a short scape (Nozaki 2021, fig. 5A), these two specimens must belong to different species. Thus, I designate here the male collected from Fukuoka (MCZ:Ent:11833) as the lectotype to fix the status of the taxon name.
As a result of the lectotype designation of A. japonica, another specimen (MCZ:Ent:648191) becomes a paralectotype. Although I could not identify this specimen at the species level, H. albomarginata is widely distributed in Gifu Prefecture and the scape of each antenna (Figs 2B, 2C) is longer than that of H. japonica (Figs 1C, 1E). Ulmer (1907) recorded H. japonica (as D. japonica), also from Gifu; but it was a misidentification of H. albomarginata (see the Remarks for that species).
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 305-308, DOI: 10.11646/zootaxa.5566.2.4, http://zenodo.org/record/14702954