Palaeagapetus nearcticus Banks 1936

Palaeagapetus nearcticus Banks 1936 (Figs. 1–6, 8, Table 1) Palaeagapetus nearcticus Banks 1936, 265, figs. 1 – 3, male; Frania & Wiggins, 1997, larva, 7, 13, 22, figs. 4, 7, 18; Schmid 1998, 31. Palaeagapetus guppyi Schmid 1951, 1 – 2, figs. 1 – 2, male; Djernaes, 2011, adult, 19, 35, 49, fig. 23; synonymized by Botosaneanu & Levanidova1987, 43. Adult (Fig. 1). Body black in life and dark brown in alcohol, 3.3 mm long in males (3.0– 3.8 mm, n=17) and 4.0 mm long in females (3.1–4.4 mm, n=4). Antennae 27- or 28-segmented (n=2), 2.7 mm long, 0.77 times as long as body in male (2.6–2.8 mm, n=2); scape (1A, B) slightly thicker and longer than other segments. Maxillary palpi (1A) each 5-segmented, segment I short and round, segments II to V cylindrical; labial palpi (1A) each 3- segmented, all segments cylindrical; both pairs of palpi covered with fine setae. Head (1A, B): large anteromesal setal wart (am) and pair of small anterior setal warts (a) often fused, pair of posterior setal warts (p) round, pair of posterolateral setal warts (pl) large; numerous setae scattered on anterior 1/3. Pronotum with two pairs of round warts, mesoscutum with pair of long oblique warts, and mesoscutellum with single subtriangular wart. Wings (1C) broad, black, covered with short black hairs, with few small white spots in middle of each forewing. Length of each forewing and hind wing, respectively: 4.0 mm and 3.5 mm in males (3.8–4.3 mm and 3.1–3.9 mm, n=17), 4.2 mm and 3.6 mm in females (4.1–4.5 mm and 3.4–3.9 mm, n=4). Forewings each with apical forks 1–5 and hind wings lacking fork 4; discoidal cell present in male and absent in female. Venation variable individually and even on opposite sides of same specimen; cross veins r and s absent in forewings of some male and female specimens; apex of Sc joined to R 1 in hind wings of some female specimens. Spurs 2, 4, 4. Lateral bulges (gland) of sternum V (1D, J) round. Acute ventral process developed on segment VII in male (1D) and segment VI of female (1J). Male genitalia (Figs. 1E–I). Segment IX short, anterolateral margins long, projecting to middle of segment VIII. Lateral appendages of tergite IX (la ap) developed from mid-lateral region of genital capsule, slightly variable individually (1E, H, I); long, 1.2 times as long as capsule, directed caudad and tribranched at middle; dorsal branches (db) longest, with many fine spines at apical half and each with single seta apically; middle branches (mb) as long as 1/2 of dorsal branches, thickest, each completely covered with fine spines and with single seta apically; ventral branches (vb) shortest, 1/4–1/5 length of dorsal branches, each with single seta and several spines apically. Tergite X (tX) depressed dorsoventrally, curved dorsad apically in lateral view (1E), semicircular in dorsal view (1F). Inferior appendages (1E, G, ia) short, each divided into dorsal lobe (dl) and ventral lobe (vl); lobes subequal in length, subacute apically; dorsal lobe curved mesad, ventral lobe directed caudad. Phallus (1E, G, ph) short, broad, membranous with small sclerotized structure inside. Female genitalia (Figs. 1J, K). Segments I–VII very setose, each with sclerotized tergite and sternite, tergite VIII unpigmented at anterior half and slightly pigmented at posterior half. Segments IX–X very short, each segment about 1/6th as long as segment VIII, with somewhat developed cerci. Vaginal apparatus (1K) slender, lateral projections undeveloped, lateral bands round. Pupa (Fig. 2). Body (2A) slightly depressed dorsoventrally; length up to 4.0 mm. Antennae and wing pads reaching to abdominal segment V or VI (2A). Mandibles (2B) triangular, each with numerous minute teeth and large tooth on inner edge. Pair of hook plates (2A, C, D) present near anterior margins of each of segments III–VII and near posterior margins of segments III–V, 10–18 hooks on each plate. Anal process (2A) thick and round apically. Instars of larva (Fig. 3). Head widths of larvae reared from eggs in laboratory and collected on Mary’s Peak, Oregon, 1982–1983 (see ‘Habitat and specimens’), separating into 5 groups, suggesting 5 instars as follows: 1st instar 0.15–0.16 mm, 2nd instar 0.18–0.19 mm, 3rd instar 0.22–0.25 mm, 4th instar 0.28–0.32 mm, and 5th instar 0.36–0.39 mm, respectively. Final (5 th) instar larva (Fig. 4). Body (4A) suberuciform, length up to 5 mm, flattened dorsoventrally, widest at abdominal segments III–V, membranous portion whitish yellow and sclerites deep brown. Head (4B, C): Width subequal to length, black to deep brown except light eye spot, 18 primary setae present, secondary setae or spines absent; antennae (4C inset) situated just beneath anterior corner of eye spot; anterior ventral apotome subtriangular with concave anterior margin, posterior ventral apotome indistinct. Mandibles (4E, F) deep brown, stout, each with three teeth dorsally, mesal brush of left mandible with setae longer and more numerous than of right one, setae of brushes slightly serrate (4F inset). Labrum (4D) light brown, anterior margin deeply concave. Thorax (4A, G): Each segment dorsally covered by two, deep brown, square sclerites bearing about 55, 45 and 45 setae on each of pro-, meso- and metanotal plates; posterior margin of pronotum (4G) dark, posterior margins of meso- and metanota deep brown. Propleuron (4H, upper) rectangular with distinct pleural sutures separating it from foretrochantins; meso- and metapleura (4H, middle and lower) each crescentic with no distinct pleural sutures. Three thoracic legs (4H) brown, similar in structure, tarsi with two enlarged apical spurs, trochanter or femur with no ventral brush. Abdomen (4A): Segments I–VIII each with pair of truncate lateral tubercles, segment I with three small sclerites and about 40 setae, segments II–VIII each with 8–12 setae; dorsal tergite IX (4I) deep brown, semicircular with concave anterior margin and with about 30 long setae; lateral sclerites of anal prolegs (4J) rectangular, pale brown; anal claws (4J) strongly curved ventrad, deep brown without accessory hooks or denticles. Early (1 st –4 th) instar larvae (Figs. 5A–G). Campodeiform (5A), sclerites brown in 4th instar larva and lighter in younger instar larvae, thorax and abdomen very setose. Head (5A) length subequal to head width, with 18 primary setae; thoracic segments (5A) covered with two dorsal plates, each dorsal plate with 60–70 setae. Abdominal segments I–VIII (5A–D) each with rectangular dorsal sclerite, pair of lateral humps and lateral tubercles, lateral tubercles indistinct in earlier instar larvae, each segment with many setae and sensillae (5B–D). Dorsal sclerite IX (5E–G) with about 30 setae and several sensillae; anal legs (5A inset) extended caudad, without accessory hooks or denticles. Other characters as in final instar larva. Egg (Fig. 5H). Eggs orange, spherical, about 0.2 mm in diameter, and separately deposited on leaves of liverworts. Case (Fig. 5I). Case of final instar larva up to 7 mm long, depressed dorsoventrally and composed of two valves with slit-like openings at front and rear. Each valve consisting of roundish or oval pieces of liverwort. Food and feeding behavior (Fig. 5J). Larvae eat leaves of the liverwort, Scapania uliginosa (Sw. ex Lindenb.) Dumort. (Jungermannidales, Scapaniaceae). They pierce cell walls and swallow contents of cells one at a time. Emergence (Fig. 2E). Emergence was observed in the laboratory (Corvallis, Oregon,) in late July, 2009. Teneral adults emerged on leaves of liverwort in the morning (5:30–9:30 AM). The newly emerged adults stretch their wings and abdomens in an upright position like mayflies, which takes ca. 3 minutes (n=2). Annual life cycle (Fig. 6). Occurrence of 5 development stages in British Columbia (B); Washington (W); Mary’s Peak, Benton County, Oregon (M); other sites of Oregon (O); and California (C) were summarized in 10- day periods based on the collecting data in “habitat and biology” and Table 1 in Fig. 6. Collection records that did not specify early or final instar larvae were omitted from the figure. Eggs and early instar larvae were found mainly in late July and September–early November, respectively. Final instar larvae were seen from September to the following July. Adults occurred mainly in June to September. Therefore, a univoltine life cycle with a summer emergence season was suggested as shown by the grey band in Fig. 6. However, another annual cycle could be supposed for a few populations, because some adults and early instar larvae were collected in April–May and June, respectively. Habitat and biology. The larvae live in springs, spring brooks and seepage areas of forested mountain streams, often just above the water surface and in hygropetric habitats, and they are exclusively associated with moss and liverwort. Observation at Mary’s Peak, Benton County, Oregon. Many springs and seeps enter the stream around 1100–1200 m elevation where the channel is 1–2 m wide; moss and the liverwort Scapania ulinosa are abundant; cold year-round water regime. Many larvae and pupae of P. nearcticus were found in the liverwort and moss on cobbles and logs mainly just above water. Specimens were collected and deposited by RWW unless otherwise indicated: 21 August 1952, V. Roth, 1 male; 03 September 1982, many 5th and early instar larvae; 20 September 1981, 22 1 st –4 th instar larvae; 31 October 1981, 26 empty pupal cases, no larvae found; 30 May 1982, many 5 th - instar larvae; 03 November 1982, 1 st to 4 th- -instar larvae and many 5 th -instar larvae with newly constructed cases; 27 April 1983, 15 5 th -instar larvae; 09 August 1983, about 60 adults; 29 July 2009, 2 males, 2 females, 10 pupae, 2 5 th - instar larvae, 5 eggs, RWW & TI (TI); 07 July 2010, no larvae or adults; 01 August 2010, 4 males, many adults seen. Observation at Flynn Creek, Lincoln County, Oregon. Oregon Coast Range, Flynn Creek, 44.53°N, 123.87°W, 150–300 m, 3 rd -order stream and tributaries, 0.3–3 ba

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