Lepidostoma coreanum ( Kumanski & Weaver 1992 )

Ito, Tomiko, 2016, The Lepidostoma coreanum Species Complex (Trichoptera, Lepidostomatidae) in the Asian Far East, Zootaxa 4061 (4), pp. 397-417 : 398-403

Lepidostoma coreanum ( Kumanski & Weaver 1992)

( Figs. 1–6 , 21 )

Indocrunoecia coreana Kumanski & Weaver 1992 , 163–165, male, female, North Korea (Province Pyongan Pukudo). Dinarthrum coreanum: Ito 1998 , male, female, larva, case, Russian Far East (Primorye, Khasanski), Japan (Honshu: Shizuoka (Amagi-yugashima-cho), Wakayama); Ito et al. 2002, 23, Japan (Shikoku).

Lepidostoma coreanum: Weaver 2002 , 180; Ito 2005, 504, 507, 512, male, larva.

Male ( Figs. 1–5 ). Specimens from Primorye ( Fig. 1 ). Antennae about 5.5 mm long, scape setose, thick and long, 1.5 times as long as head, short mesal process near middle of each scape. Maxillary palps extremely setose, each 2- segmented, 0.8 mm long in total, basal segment curved anteriorly at half its length with tuft of very long setae apically, long apical segment emerging near middle of basal segment. Labial palps each 3-segmented, slender, 1.0 mm long in total.

Wings covered with fine setae, short scales, and spindle-like setae; spindle-like setae lined and circled in coastal area; forewings each with discoidal cell, thyridial cell, and apical forks 1 and 2, Cu2 indistinct at basal half and fused to Cu1 and A1+2+3 apically, arculus large; hind wings each with fork 1, Cu2 fused to Cu1 apically, A1+2+3 also fused to Cu1 apically; forewings and hind wings each 5.0– 5.2 mm long and 4.7–4.8 mm long, respectively (n=3).

Genitalia. Abdominal segment IX (IX) short, dorsum longer than venter. Segment X (X) composed of slender mesal (ma), lateral (la), and ventral arms (va); mesal arms longest and directed caudad, lateral arms directed caudad and distinctly shorter than mesal arms, ventral arms curved slightly dorsocaudad with length subequal to lateral arms; 3 arms subacute apically. Inferior appendages (ia) setose, each composed of main article (maia), dorsal hook (dh), and inner hook (ih); basal half of main article broad in lateral view, semicircular with serrate posterior margin in ventral view; apical half of main article bar-like, curved mesad, mesocaudal apex rather acute; dorsal hook directed laterocaudad, length subequal to main article; inner hook much shorter than dorsal hook, bar-like and directed laterocaudad. Phallic apparatus thick, apical half membranous with inner U-shaped sclerite, paramere absent.

Variation ( Figs. 2–5 ). Specimens of all 4 localities in Japan exhibit some variations. In a male from Amagiyugashima-cho, Shizuoka ( Fig. 2 ), the genitalia are almost identical to those of males from the type locality in North Korea ( Kumanski & Weaver 1992) and from Primorye ( Fig. 1 ), but the wing venation and maxillary palps are a little different from those of the later; in the Amagi-yugashima-cho specimens, Ma and Mp are stalked, crossvein m-cu and the thyridial cell are absent in each forewing; crossvein m-cu and the apical parts of Cu2 and A1+A2+A3 are lacking in each hind wing; the basal segment of each maxillary palp is thickened apically and the long apical segment emerges from the basal 2/3 of the basal segment.

In a male from Wakayama ( Fig. 3 ), the lateral arms of segment X are reduced, hump-like; the basal 2/3 of Cu2 is lacking in each forewing.

In the males from Ehime ( Fig. 4 ) and Kochi ( Fig. 5 ), the lateral arms of segment X are reduced to a low hump, the main article of each inferior appendage has a round convex posteromesal margin in ventral view. The maxillary palps are setose, short, and unsegmented. Cubital and anal veins of forewings and hind wings are not fused apically and an arculus is absent in cubital area and some crossveins are lacking. Cu1 has a short apical fork 5 in each hind wing of a specimen from Kochi.

Female ( Fig. 6 A–F). Specimens from Primorye. Antennae about 5.5 mm long, scape setose, thick, long and 2 times as long as head, mesal processes absent. Maxillary palps each 5-segmented and about 1 mm long, labial palps each 3-segmented and 0.6 mm long; all palps slender.

Wings covered with short fine setae, typical venation in females of the family; forewings with apical forks 1, 2, 3, 5, discoidal and thyridial cells, and arculus; hind wings with forks 1, 2 and 5. Lengths of forewings and hind wings on each side 5.1–6.0 mm and 4.0–5.0 mm, respectively (n=5).

Lateral ends of tergite VIII broad. Lateral plates weakly sclerotized, trianglular. Subgenital plate sclerotized, subquadrate with slightly concave posterior margin and middle depression on anterior margin. Vaginal apparatus oval and slightly sclerotized.

Larva ( Figs. 6 G, H). Specimens from Primorye. Head width and body length of final instar larva up to 0.7 mm and 7 mm, respectively. Head dark brown, with numerous short secondary setae on dorsum in early instars. Pronotum dark brown. Mesonotal plate brown with some light colored dots on anterior half and light brown on posterior half. Chaetotaxy of thorax: 35–40 setae on pronotum; 7, about 12 and about 12 setae on setal areas (sa) 1, sa 2 and sa 3, respectively, of mesonotum; and 1, about 5, and about 12 on sa 1, sa 2, and sa 3, respectively, of metonotum. Single tracheal gills present in subdorsal rows near posterior margins of segments II–VI, in subventral rows near posterior margins of segments II–VII, and in subdorsal rows near anterior margins of segments II–III (or II–IV or II–V). Single subventral gill present near anterior margin of segment II in some specimens. Other characters as in L. robustum ( Ito 1984) .

Case of larva ( Fig. 6 I). Specimens from Primorye. Cylindrical, slightly curved and slightly tapered posteriorly, composed of sand grains with round posterior opening. Length up to 10 mm.

Remarks. The males of this species have some variations locally but they are clearly distinguished from those of other related species by their elongated ventral arms of segment X. Records of this species from Mie, Honshu, Japan, by Kawase and Morita (2001, 2010) and Morita (2008, 2011) are uncertain because the specimens could not be examined with our present taxonomic knowledge.

Specimens examined. Russian Far East, Primorye, Khasanski: 4 males, small water flow near Vitya Village, 30.vi.1988, T.S. Vshivkova; 5 larvae, same locality, 11.v.1996, T.S. Vshivkova & T. Ito; 1 male, 6 females, 2 pupae (1 male, 1 female), same locality, 11.v.1996 (larvae), reared and preserved in alcohol in vi.1996, T.S. Vshivkova & T. Ito. Japan, Honshu, Shizuoka: 1 male, 1 female, 2 pupae (females), Izu-shi, Amagi-yugashimacho, Kami-funabara, Funabara-gawa, 550 m, 21.iv.1996 (larvae), reared and preserved in alcohol on 24.vi.1996, T. Hattori & T. Ito. Wakayama: 1 male, Kozagawa-cho, Hirai, 20.v.1993, N. Kuhara, light trap. Shikoku, Ehime: 3 males, 1 female, Uchiko-machi, Odamiyama, Miyamaso-mukai, small water flow, 24.vii–8.viii.2000, E. Yamamoto, Malaise trap; 3 females, Kuma-kogen-cho, Yurano-no-mori, 30.vi–31.vii.2007, E. Yamamoto, Malaise trap. Kochi: 1 male, Okawa-mura, Funato, Yoshino-gawa, 378 m, 27.iii.2004, K. Nio.

Distribution ( Fig. 21 ). North Korea (Province Pyongan Pukudo), Russian Far East (Primorye, Khasanski), Japan (central Honshu, Shikoku).

Habitat. Adults were collected from small water flows in forests.

Japanese name. Korea-sunatsutsu-tobikera.

Figures

FIGURE 1. Lepidostoma coreanum, male, specimens from Primorye. A, head, right scape and maxillary palp, right lateral; B, right scape, ventral; C, right forewing, dorsal; D, right hind wing, dorsal; E, genitalia, left lateral; F, same, dorsal; G, same, ventral. Abbreviations. Body: IX = abdominal segment IX, X = abdominal segment X; ma, la and va = mesal, lateral and ventral arms of segment X, respectively; ia = inferior appendage; ih, dh and maia = inner hook, dorsal hook and main article of an inferior appendage, respectively; ph = phallic apparatus. Wings: 1 – 2 = apical forks I and II; d = discoidal cell; th = thyridial cell; ar = arculus; C = costa; Sc = subcosta; R = radius; Ma = anterior media; Mp = posterior media; Cu = cubitus; A = anal vein.

FIGURES 2, 3. Lepidostoma coreanum, male, variation. 2, specimen from Shizuoka, Amagi-yugashima-cho; 3, specimen from Wakayama. A, head, left scape and maxillary palp, left lateral; B, right forewing, dorsal; C, right hind wing, dorsal; D, genitalia, left lateral; E, same, ventral; F, apex of main article of right inferior appendage, ventral, enlarged.

FIGURES 4, 5. Lepidostoma coreanum, male, variation. 4, specimen from Ehime; 5, specimen from Kochi. A, head, right scape and maxillary palp, right lateral; B, right forewing, dorsal; C, right hind wing, dorsal; D, genitalia, left lateral; E, same, ventral.

FIGURE 6. Lepidostoma coreanum, female, larva, and case, specimens from Primorye. A – F, Female: A, head, right scape and maxillary palp, right lateral; B, right forewing, dorsal; C, right hind wing, dorsal; D, abdominal segments VII – X, left lateral; E, same, ventral, subgenital plate omitted; F, subgenital plate, ventral, posterior edge up. G – I, Larva: G, habitus, left lateral; H, right half of thorax, dorsal. I, Case: case of larva, left lateral. G – H, from Ito (1998). Abbreviations: VII, VIII, IX, and X = abdominal segments VII – X, respectively; lp = lateral plate; sp = subgenital plate; wing labels, as in Fig. 1.

FIGURE 21. Distribution of the 5 species of the Lepidostoma coreanum Species Complex of the genus Lepidostoma. The plot in North Korea was referred from Kumanski & Weaver (1992).