Ugandatrichia nakijinensis Ito

Ito, Tomiko & Ohkawa, Ayuko, 2012, The genus Ugandatrichia Mosely (Trichoptera, Hydroptilidae) in Japan, Zootaxa 3394, pp. 48-58 : 49-54

Ugandatrichia nakijinensis Ito sp. nov.

( Figs.1–4 , 6 )

Adult. Wings black, densely covered with long black hairs, with oval patch of creamcoloured short scales (androconia according to Hsu & Chen 2002) at middle of each male forewing. Antennae black at basal 1/3 and white at apical 2/3.

Male ( Fig. 1 ). Length of forewing, hind wing and body 4.0– 4.2 mm, 3.8–3.9 mm and 3.0– 3.4 mm, respectively. Antennae each 32–33-segmented and 1.7–1.8 mm long. Wing venation somewhat variable locally, individually and even in opposite sides of single specimen; forewings each with apical forks II and III, hind wings each with forks II, III and often V.

Genitalia ( Fig. 1 ). Segment IX large, round in lateral view, large and quadrate in dorsal view. Dorsal plate membranous, tapered medially and with pair of round humps laterally. Subgenital plate distinctly longer than dorsal plate, broad-based, tapered to narrow apex, with pair of setae subapically. Inferior appendages stout, large, setose; twice as long as subgenital plate, parallelsided with round apices in dorsal and ventral views; thickened at middle, tapered distally, somewhat rounded apically in lateral view; 2 pairs of sclerotized spurs present, the first medially on mesal margin, second on dorsal surface between first spur and base of each inferior appendage. Paired sclerotized processes above inferior appendages; in lateral view broad-based, tapered to narrowly rounded apices and curved ventro-posteriorly; rod-shaped in dorsal view. Phallus long, titillator curled once around half-way, ejaculatory duct slightly projected.

Female ( Fig. 2 ). Length of forewing, hind wing and body 4.5 mm, 3.6 mm and 3.3–3.8 mm, respectively. Antennae each 30-segmented and 1.8 mm long. Wing venation of females variable as in males; forewings each with apical forks II and III, hind wings each with forks II (absent in some specimens), III and V. Segment VII: Tergite and sternite fused laterally, weakly sclerotized; tergite subquadrate with dense row of very long setae near posterior margin; sternite straight anteriorly, slightly convex laterally, with pair of patches of short setae posteriorly. Segment VIII almost as long as segment VII, sternite with postero-medial excision and 4 pairs of long setae posteriorly.

Pupa ( Fig. 2 ). Flattened dorso-ventrally, up to 4.3 mm long, milky white. Mandibles very sharp. Antennae and wing pads almost reaching to end of abdomen. Hook plates on abdominal segments III–VII; longitudinally long hook plates at middle of segments III–VII with about 35 hooks each; small round hook plates at posterior margins of segments III–V with 5–7 hooks. Lateral fringes and anal processes absent.

Larva ( Figs. 3–4 ). Final instar larva ( Figs. 3–4 ). Cylindrical, length up to 6 mm, sclerotized parts black or deep brown, other parts milky white.

Head. Uniformly dark brown, semi-rectangular, width up to 0.32 mm, length slightly longer than width; frontoclypeal suture fused; several primary setae very long, longest seta 1.8 times as long as head width. Antennae situated between anterior edge of head capsule and respective eye spots, each unsegmented with subapical seta. Mandibles stout with blunt apices, blunt teeth and dense mesal brushes; brush setae more or less serrated. Labrum weakly sclerotized, brushes of setae not visible or absent at anterior margin.

Thorax. Dorsum of each segment covered with 2 large square plates; plates dark brown with black borders on meso- and metanota; each plate with 20–25 setae. Prothorax with pair of large ellipsoidal ventral sclerites; mesothorax with pair of narrow ventral sclerites. Thoracic legs short and stout; foretibial spurs paired, subacute apically; each of middle and hind tibial spurs single, acute apically; other structures similar in three legs. Anterior part of foretrochantin elongate, rectangular with irregularly protruded margin; posterior part of trochantin ellipsoidal. Episterna small and epimera large ellipsoidal on meso- and meta-thorax.

Abdomen. Cylindrical but middle of abdomen slightly swollen. Tracheal gills, humps, lateral fringes or lateral tubercles absent. Setae on dorsum of segments I–VIII 1, 1–2 and 2 at setal area 1, 2 and 3, respectively, one seta on setal area 3 long; 2 setae at lateral line on each of segments I–VIII. Chloride epithelia with black border present near anterior margin of terga I–VIII; epithelia on tergum I round and those of terga II–VIII threelobed. Large orange ventral sclerites appearing on segments III–V, varying according to larval growth. Dorsal sclerite of tergum IX rectangular with 3 pairs of long and 2 pairs of short setae. Lateral sclerites of segment X long, rectangular with 3 pairs of long setae. Anal claws directed laterad or antero-laterad, without accessory hooks.

Early instar larva ( Fig. 4 ). Campodeiform. Head width up to 0.28 mm, body length up to 3.8 mm. Sclerotized parts brown to dark brown, other parts pale brown. Each of thoracic dorsal plates subquadrate, without ecdysial lines. Ventral sclerites absent on thorax and abdomen. Each of abdominal segments with large subquadrate dorsal sclerite. Anal prolegs rather slender and elongated postero-ventrally. Other characters as in final instar larva.

Case ( Fig. 2 ). Retreat-like cases of final instar larva and pupa made of secretion (silk), semi-transparent, rather flat, consisting of outer oval dome (net according to Malicky 1999) and inner long rectangular tube. Outer dome tightly attached to rocky substrates at anterior and posterior margins; both larval and pupal cases sometimes including filamentous algae woven together with secretion. Inner tube tightly attached to undersurface of dome, made of secretion alone never with filamentous algae; in larval stage tube, attached at four corners and with mid-lateral openings; pupal tube, tightly attached at four corners and also at middle of lateral margins. Early instar larvae of this species or larvae of Stactobia (another hydroptilid genus) or chironomids often found inside the cases.

Holotype: Japan, Okinawa, Okinawa-jima: 1 male, Nakijin-son, Shigema-gawa (26˚41’N, 127˚56’E, 75 m above sea level), 9.iv.2011, TI & T. Kitamura, S (CBM-ZI 146122).

Paratypes. 8 males, 5 females, same data as holotype (CBM-ZI 146123–146135).

Other specimens examined. Japan, Okinawa, Okinawa-jima: 30 males 5 females, same data as holotype; 4 pupae, 8 larvae, type locality, 17.iii.2012, TI & T. Kitamura, S; 1 pupa, 1 prepupa, 2 larvae, Kunigami-son, Oku, small fall, 21.iii.1999, TI & AO; 1 female, 5 larvae, Kunigami-son, Yambaru-no-mori, small fall, 21.iii.1999, TI & AO, S; 3 pupae, Kunigami-son, Fun-gawa, Tanaga-gumui, 22.iii.1999, TI & AO. Japan, Kagoshima, Amamioshima: 1 male, Yamato-son, Materia-no-taki, 29.iii.1998, H. Nishimoto; 2 males, ibid., 25–26.x.2011, TI, S; 1 female, Uken-son, Arangachi-no-taki, 26.x.2011, TI, S; 1 pupa, 11 larvae, Uken-son, a hygropetric habitat near Kawauchi-gawa, 20.iii.1999, TI & AO.

Diagnosis. The male of this species is similar to that of U. taiwanensis , in having the conspicuous sclerotized processes above the large, broad inferior appendages, but is clearly distinguished from the latter by presence of androconia on forewings, round humps laterally on dorsal plate, a dorso-mesal second spur on each inferior appendage. The females is also very similar to that of U. taiwanensis , but is distinguished from the latter by the shape of sternite VII in ventral view with posterior margin smoothly rounded compared to the large convex area of short dense setae in U. taiwanensis . Pupae and larvae are very similar to those of U. taiwanensis and could not be distinguished from those of the latter.

Etymology. The specific name refers to the type locality.

Distribution ( Fig. 6 B). Japan (Okinawa-jima, Amami-Οshima).

Habitat ( Fig. 6 A). Larvae and pupae of this species live on smooth surfaces of rocks on waterfalls and in very fast flowing waters.

Japanese name. Nakijin-ô-hime-tobikera.

Figures

FIGURE 1. Ugandatrichia nakijinensis. Male (B, Amami-oshima, Yamato-son; others, type locality in Okinawa-jima). A, B, right wings, dorsal; C, head and thorax, dorsal; D, maxillary palpus; E, labial palpus; F, genitalia, left lateral; G, same, dorsal; H, same, ventral; I, distal part of subgenital plate, dorsal; J, phallus, dorsal; K, same, right lateral. Abbreviations: 2 – 5, 2 nd – 5 th apical forks; IX, abdominal segment IX; dp, dorsal plate; ia, inferior appendage; ph, phallus; psp, paired sclerotized process; sp, subgenital plate; ti, titillator.

FIGURE 2. Ugandatrichia nakijinensis. Female, pupa and cases (B, Amami-oshima, Yamato-son; others, type locality). Female (A – D): A, B, right wings, dorsal; C, segments VII – X, left lateral; D, same, ventral. Pupa (E – I): E, dorsal; F, right mandible, dorsal; G, long hook plate; H, round hook plate; I, posterior parts of abdomen, dorsal. Case (J – L): J, pupal case, from below; K, larval case, from below, larva stretches out from one of lateral openings; L, enlarged figure of part of case made of silk together with filamentous algae. Abbreviations: 2 – 5, 2 nd – 5 th apical forks; VII – X, abdominal segments VII – X.

FIGURE 3. Ugandatrichia nakijinensis. Final instar larva (type locality). A, left lateral; B, head, dorsal; C, same, ventral; D, labrum, dorsal; E, right mandible, dorsal; F, mesal seta of mandible; G, pro- and meso-thoracic segments, ventral; H, abdominal segment III, ventral; I, abdominal segment VIII, dorsal.

FIGURE 4. Ugandatrichia nakijinensis. Final and early instar larvae (type locality). Final instar larva (A, B): A, 3 thoracic legs and pleura; B, abdominal segments IX and X, dorsal. Early instar larva (C, D): C, dorsal; D, abdominal segments IX and X, dorso-lateral.

FIGURE 6. Habitat and distribution. A, A typical stream habitat of Ugandatrichia nakijinensis, with 3 sites where larvae and pupae were found indicated by circles (type locality); B, distribution of the 2 species.