Tsudaea kitayamana ( Tsuda 1942 )

Nozaki, Takao, 2009, Tsu da ea, a new genus of Brachycentridae (Trichoptera) from Japan, Zootaxa 2131, pp. 54-64 : 56-63

Tsudaea kitayamana ( Tsuda 1942)

Figures 1–5, 8, 9

Brachycentrus kitayamanus Tsuda 1942 , 326, male.

Micrasema sp. MD: Akagi 1962, 44–45, larva, case.

Eobrachycentrus kitayamanus: Wiggins et al. 1985 , 66–67; Morita and Kawase 2004, 18.

Description— Adult ( Figs. 1 , 2 , 8 ). Body, wings and antennae dark brown, almost black. Forewings 4.6–6.8 mm long in male, 4.4–7.5 mm long in female; slenderer in female than in male. Head shorter than width; ocelli absent; anterior setal warts oval, smaller in female than in male; both posterior and posterolateral setal warts slender; large round setal wart present on center of frons, with pair of large rectangular setal warts laterally. Male maxillary palpi very short, about 0.2 mm long in total length; 3-segmented; third segment usually minute, but males from Ishikawa and Hyogo with third segment approximately same length as second segment. Female maxillary palpi 5-segmented, 0.8–1.2 mm long in total length, ratio of five segments approximately 1: 1: 3: 2.5: 2.6. Labial palpi 3-segmented in both sexes, first segment short, third segment longest; total length 1.0–1.2 mm long in male, 0.4–0.7 mm long in female. Antennae shorter than forewings in both sexes, scape 2.7 times as long as wide. Pronotum with pair of oval setal warts dorsally and pair of ovoid setal warts laterally, approximately same size as dorsal pair. Both mesoscutal and mesoscutellar setal warts small, oval. Legs with tibiae and tarsi brown; tibial spur formula 2, 3, 3 in both sexes; with brown spine-like setae present on tibiae and first to fourth segments of tarsi of all legs. Discoidal cell elongate and closed in fore- and hindwings of both sexes. Forewing venation similar in both sexes; apical forks I, II, III and V present, fork II petiole; crossveins c-sc and sc-r at middle of anterior margin and near distal end of Sc, respectively; crossveins r-m and m-cu present; anal veins A1 and A2 fused into a single vein, A3 absent. In hindwings, apical forks I, II and V present in male; I, II, III and V present in female; fork II petiole in female, but usually branching close to discoidal cell in male. Abdominal sternite V with pair of scent glands near anterolateral margins. Abdominal sternite VII with small triangular process at middle of posterior margin; apex round in male, acute in female.

Male genitalia ( Fig. 2 A–F). Segment IX triangular in lateral view, narrow dorsally. Segment X long, deeply divided into two long triangular lobes separated by deep V-shaped notch in dorsal view; weakly sclerotized and lightly pigmented, with small, rounded preanal appendages basolaterally. Intermediate appendages large and oval in lateral view, slightly shorter than segment X, anterodosal corner angled laterally. Inferior appendages 2-segmented: basal segment large, trilobed posteriorly in lateral view, dorsal process long and finger-like in lateral and dorsal view, and protruding slightly posteroventrally in lateral view; distal segment rectangular in lateral views, apex with three, short, strong, spine-like setae. Phallus with sclerotized phallotheca almost straight; endotheca usually with three pairs of long spines at base, two dorsally, one ventrally (sometimes absent); aedeagus broad dorsoapically, distal end of ejaculatory duct and phallotremal sclerite darkly pigmented.

Female genitalia ( Fig. 2 G–I). Sternite VIII large, trapezoidal and as long as wide ventrally. Tergum IX short, approximately same length as segment X, with short, rounded, posteroventral process in lateral view. Segment X bilobed, each oval in dorsal view. Spermathecal sclerite simple, anterior half rectangular and slender in ventral view.

Larva ( Figs. 3 A–J, 9). Length up to 8 mm. Head mostly dark brown, almost black, round in dorsal view; dorsum flat, surrounded by distinct carina; antennae located approximately midway between eye and labrum; setae 1, 4, 11,16 and 17 transparent; setae 5, 6 and 18 very short, seta 14 longest. Ventral apotome rectangular, about 2 times as long as wide. Labrum hairy along its anterior margin; mandibles each with pair of long setae laterally and mesal brush of fine hairs, with two or three apical teeth (sometimes indistinct); maxillary lobe setose; submental sclerites fused into single triangular plate, bearing pair of setae anterolaterally. Prosternal horn absent. Pronotal sclerites dark brown, anterior half and posterior margin darker brown, anterior margin and transverse depression bearing many long, stout setae. Mesonotal sclerites mostly pale brown with posterior margin dark brown; each sclerite subdivided longitudinally, with anterior and posterior margins of mesal sclerite bearing long, stout setae, setae also arising from anterolateral corner to middle part of lateral sclerite. Metanotal sa1 with one short seta, sa 2 and sa 3 sclerites each oval with long, stout setae. Forelegs short, approximately half length as mid- and hind legs, coxae with many long setae, femora broad with six tooth-like spines ventrally. Mid- and hindlegs slender; coxae with many long setae; long setae arising on ventral and dorsal edges of trochanters, femora, tibiae and tarsi. Abdominal segment I with pair of lateral humps, humps with many tiny setae apically. Abdominal segment II with pair of single gills posteroventrally. Lateral fringes present on abdominal segment III to VII, very short, unpigmented. Forked lamellae absent. Abdominal segment VIII with pair of dorsolateral lobes. Dorsal sclerite of segment IX rectangular, concave laterally; posterior margin with ten long setae. Lateral sclerite of anal prolegs with one long seta on posteromesal corner; basal tuft with three long setae, mesal seta longest; anal claw with two dorsal accessory hooks.

Pupa ( Fig. 4 ). Length 7–8 mm. Antennae shorter than body, scape with several short setae dorsally and ventrally. Head with three pairs of setae on vertex and frons, two pairs of setae between each eye and mandible, each eye with one seta. Labrum with five pairs of long, apically-hooked setae, one pair of short transparent, basolateral setae; and three pairs of minute apical setae. Mandibles acute with many fine teeth on mesal margin. Tarsi of midlegs with dense fringe of setae. Abdominal segment I with pair of spined ridges near posterior margin; anterior hook plates present on segments III to VII, with 7 to 16 spines, plates on III to VI slender, plates on VII long oval; segment V with two rows of spines posteriorly. Abdominal gills absent. Lateral fringe present from posterior part of segment V to posteroventral part of segment VIII. Anal processes shorter than segment IX; each process with two, long, apically-hooked setae apicomesally and one short, thick, apical claw-like seta having its apex slightly curved.

Case ( Figs. 4 , 9 ). Case of final instar larva up to 8 mm long, constructed of sand grains, straight, tapered, with many loosely attached moss pieces and other plant materials; posterior end closed by silk and sand with central hole. Prior to pupation, posterior end of case is attached to moss and both anterior and posterior openings closed by silken membrane with many perforations.

Specimens examined. Ishikawa: 2 males (in alcohol), Shaka-rindo, Shiramine, Hakusan-shi, 26.V.2001, H. Kawase (HM). Ya ma n a s h i: 1 larva, Yato, 1,060 m a.s.l., Oizumi-cho, Hokuto-shi, 28.XII.1979, T. Ito (TN). 4 larvae, Sakubadaira, 1,310 m a.s.l., Ichinose, Enzan-shi, 35˚50’16”N, 138˚49’20”E, 3.IV.2004, D. Tsuruta (TN). 4 larvae, ibid., 21.XI.2004, D. Tsuruta (TN). 11 males, 7 females (3 males and 2 females pinned, others in alcohol), 13 pupal skins, ibid., larvae collected on 8.IV.2005, emerged 11–13.V.2005, T, Nozaki (2 males & 1 female (pinned): CBM, 7 males, 4 females (in alcohol): TN, 2 males, 2 females (1 male & 1 female pinned, others in alcohol): USNM). 5 larvae, ibid., 13.X.2005, T. Nozaki (TN). 2 pupae, ibid., larvae collected on 13.X.2005, fixed 18.III.2006, T. Nozaki (TN). 9 larvae, 1 prepupa, ibid., 16.IV.2006, T. Nozaki (3 larvae: CBM, 4 larvae, 1 prepupa: TN, 2 larvae: USNM). Nagano: 2 males (pinned), Piratasu-nooka, 1,630 m a.s.l., Chino-shi, 14.VI.1992, T. Hattori (CBM). 11 males (in alcohol), Mitsumata, 1,400–1,600 m a.s.l., Karasu-gawa, Horigane, Azumino-shi, 31.V.1997, T. Hattori (TN). 1 larva, Wada-gawa, Nagawamachi, 5.IV.1991, H. Kato & Sugiyama (TN). Gifu: 2 larvae, Hodaka-no-mori, Okuhida-onsengo, Kamisaka, Takayama-shi, 31.X.2005, K. Hatano (TN). Mie: 1 male (in alcohol), Myojin-daira, Iitaka-cho, Matsusakashi, 8.V.1999, H. Morita (HM). Hyogo: 2 males, 1 female (in alcohol), Hachibuse-yama, 900 m a.s.l., Yabushi, 3.V.2005, K. Inazu (TN).

Distribution ( Fig. 5 ). Japan (central Honshu).

Biology. Larvae of this species were found in moss in cool streams and ponds in high mountain areas. Most specimens used in this study were collected at or above 900 m in elevation. At a headwater of the Tama River, Ichinose, Enzan, Yamanashi, larvae were collected mostly from moss attached to boulders in the margins of the stream ( Figs. 6–7 ). However, sometimes larvae of T. kitayamana were found on mossy boulders in rapids, where larvae of Eobrachycentrus vernalis ( Banks 1906) were found commonly. The most abundant moss at both the margins and rapids of streams inhabited by these two species is Rhynchostegium riparioides (Hedw.) . This suggests that current velocity, interspecific competition, or other factors may be responsible for the physical separation in their respective microhabitats. Larvae collected on 13.X.2005 and provided only Java Moss, Taxiphyllum barbieri (Card. and Copp.) , for food in an aquarium developed to the adult stage. Larvae of this species probably feed on moss such as R. riparioides in mountain streams. Collections for this study suggest that T. kitayamana has a univoltine life cycle with a late spring flight period.

Figures

FIGURE 1. Tsudaea kitayamana. A: male adult, head and pro- and mesonota, dorsal; B: Male adult, head, frontal; C, male, head, lateral; D, male, maxillary palp, lateral (D 1: Yamanashi, D 2: Hyogo); E, female, maxillary palp, lateral; F, male, wings; G: female, wings.

FIGURE 2. Tsudaea kitayamana. Male genitalia A – F: A, lateral; B, dorsal; C, ventral; D, inferior appendage, mesal; E, phallus, dorsal; F, phallus, lateral. Female genitalia G – I: G, lateral; H, dorsal; I, ventral. Abbreviations: IX, X, abdominal segments IX and X; ae., aedeagus; b. s., basal segment of inferior appendage; d. s., distal segment of inferior appendage; int., intermediate appendage of segment X; pr. preanal appendage.

FIGURE 3. Tsudaea kitayamana. Larva A – J: A, lateral; B, head, dorsal, primary setae numbered; C, head, ventral, primary setae numbered; D, left mandible, dorsal; E, right mandible, dorsal; F, head, thorax and abdominal segment I, dorsal; G, foreleg, lateral, ventral margin of femur enlarged; H, midleg, lateral; I, hindleg, lateral; J, abdominal segment IX, dorsal.

FIGURE 4. Tsudaea kitayamana. Pupa A – B: A, dorsal, row of spines of abdominal segment V, anterior hook plate of abdominal segment VI and right anal process enlarged; B, head, frontal, apex of right mandible enlarged. Case C – E: C, lateral; D, caudal; E, anterior closure of pupal case, frontal.

FIGURES 5 – 9. Tsudaea kitayamana. 5: Map of Honshu, showing collection sites with arrow pointing to the type locality. 6: Habitat at headwater of the Tama River, Enzan, Yamanashi. 7: Larval microhabitat, mossy boulders in marginal area. 8: Adult female, scale: 1 mm. 9: Larva, scale: 1 mm.