Lepidostoma niigataense, Ito, Tomiko, 2016

Ito, Tomiko, 2016, The Lepidostoma coreanum Species Complex (Trichoptera, Lepidostomatidae) in the Asian Far East, Zootaxa 4061 (4), pp. 397-417 : 403-407

Lepidostoma niigataense sp. nov.

( Figs. 7–11 , 21 )

Dinarthrum coreanum: Ito 1998 , male, Japan (Honshu: Miyagi, Yamagata, Kanagawa), in part, misidentification. Lepidostomatidae gen. sp.: Nozaki 1997, 37, Japan (Honshu: Kanagawa).

Diagnosis. Males of this species are very similar to those of Lepidostoma coreanum ( Kumanski & Weaver 1992) , but are clearly discriminated from the later by the triangular lateral arms and greatly reduced ventral arms of tergum X. Females of this species are difficult to discriminate from those of L. coreanum .

Male ( Figs. 7–11 ). Type specimens ( Fig. 7 ). Antennae about 6 mm long, each with scape setose, thick and long, 2 times as long as head, short mesal process near middle. Maxillary palps extremely setose, each 2-segmented, 0.6 mm long in total, basal segment curved anterad at basal 2/3 with tuft of very long setae apically, long apical segment emerging near middle of basal segment. Labial palps each 3-segmented, slender, 0.8 mm long in total.

Wings covered with fine setae, short scales, and spindle-like setae; spindle-like setae lining and encircling especially the cubital area; forewings each with apical forks 1 and 2 and discoidal cells, Cu1 and Cu2 fused with each other for apical 1/4; hind wings each with apical fork 1, Cu unbranched, and vein A lacking; forewings and hind wings each 5.2–6.2 mm long and 4.7–5.0 mm long, respectively (n=3).

Genitalia. Abdominal segment IX short, dorsum slightly longer than venter. Segment X composed of mesal arms, lateral arms and reduced ventral arms; mesal arms long, more or less compressed laterally, directed caudad with subacute apices; lateral arms triangular or subquadrate, about 1/3 as long as mesal arms; ventral arms reduced to short slender bars. Inferior appendages setose, each composed of main article, dorsal hook, and inner hook; basal half of main article broad in lateral view, broad with serrate posteromesal hump in ventral view; apical half of main article thick bar, curved mesad with comb-like apex; dorsal hook bar-like, directed caudad, slightlly shorter than main article; inner hook much shorter and more slender than dorsal hook, bar-like and directed laterocaudad. Phallic apparatus thick, membranous in apical half with inner U-shaped sclerite, paramere absent.

Variation ( Figs. 8–11 ). Specimens collected from all 4 localities of Japan show some variations. In a male from Yamagata ( Fig. 8 ), the genitalia and wings are almost identical with those of males from the type locality in Niigata ( Fig. 7 ), but maxillary palps different from those of the later, with the apical segment short, about 1/2 as long as the basal segment.

In the males from Miyagi ( Fig. 9 ), the mesal arms of segment X are somewhat short relative to those of males from the type locality, the ventral arms of segment X are reduced to low triangular lobes, the main article of each inferior appendage is round and without posteromesal humps in ventral view. Thyridial cell present in each forewing and second segment of each maxillary palp very short.

In the males from Kanagawa ( Fig. 10 ), the mesal arms of segment X are rather short and the ventral arms are reduced to low triangular lobes; the main article of each inferior appendage has a cleft apically. The wings are almost the same as those of the type specimens, but crossvein m (Ma-Mp) and vein Cu2 are present in each hind wing. The apical segment of each maxillary palp is short, about 1/3 as long as the basal segment.

In the males from Aichi ( Fig. 11 ), the ventral arms of segment X are reduced to low triangular lobes. The wings are almost the same as those of the type specimens, but cross vein m (Ma-Mp) and apical fork 3 are present in each hind wing. Apical segment of each maxillary palp very short.

Female ( Fig. 7 I–K). Type specimens. Antennal length indeterminate due to specimen condition, scapes 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, venation typical of other species of Lepidostomatidae ; forewings and hind wings each 5.2–6.4 mm long and 4.4–5.4 mm long, respectively (n=2).

Lateral ends of tergite VIII broad. Lateral plates sclerotized, narrow, long rectangular. Subgenital plate weakly sclerotized, subquadrate, with slightly concave posterior margin and deeply concave anterior margin. Vaginal apparatus oval and slightly sclerotized.

Immature stages. Unknown.

Holotype: Japan, Honshu, Niigata: 1 male, Minami-uonuma-shi, Yamato-machi, Mizunashi-gawa, 37˚08’26”N, 139˚01’19”E, 300 m a.s.l., 4.vii.1996, T. Hattori, light trap (CBM-ZI 151250).

Paratypes. 2 males, 2 females, same data as holotype (CBM-ZI 151251 – 151254).

Other specimens examined. Japan, Honshu, Niigata: 1 male, 5 females, same data as holotype. Yamagata: 1 male, Nagai-shi, Nogawa, 21.viii.1996, T. Hosoe. Miyagi: 1 male, 1 female, Sendai-shi, near Futakuchi-onsen, hygropetric zone, 7.vi.1974, T. Hattori; 1 male, 1 female, same locality, 1.vi.1994, T. Ito. Kanagawa: 1 male, Yamakita-machi, Shiroishi-zawa, 15.vi.1984, T. Nozaki; 2 males, 2 females, Kiyokawa-mura, Shiomizu-gawa, 690 m, 5.vi.1994, T. Hattori. Aichi: 3 males, Shinshiro-shi, Shimoyoshida, Adera, hygropetric zone on walking trail to Adera-no-taki Fall, 27.vii.2012, H. Nishimoto.

Etymology. The specific name refers to the name of the type locality.

Distribution ( Fig. 21 ). Japan (northen and central Honshu).

Habitat. Adults were collected from small streams in forests.

Japanese name. Niigata-sunatsutsu-tobikera.

Figures

FIGURE 7. Lepidostoma niigataense, male and female, type specimens. A – H, Male: A, head, right scape and maxillary palp, right lateral; B, right scape, dorsal; C, right forewing, dorsal; D, right hind wing, dorsal; E, genitalia, left lateral; F, variation of segment X, left lateral; G, genitalia, dorsal; H, same, ventral. I – K, Female: I, abdominal segments VIII – X, left lateral; J, same, ventral, subgenital plate omitted; K, subgenital plate, ventral, posterior edge up. Abbreviations as in Fig. 1.

FIGURES 8, 9. Lepidostoma niigataense, male, variation, 8, specimen from Yamagata; 9, specimen from Miyagi. 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.

FIGURES 10, 11. Lepidostoma niigataense, male, variation. 10, specimen from Kanagawa; 11, specimen from Aichi. 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.

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).