Agapetus walkeri (Betten and Mosely)

Etnier, David A., Parker, Charles R., John T. Baxter, Jr., Long, Todd M. & Drive, News Sentinel, 2010, A review of the genus Agapetus Curtis (Trichoptera: Glossosomatidae) in eastern and central North America, with description of 12 new species, Insecta Mundi 2010 (149), pp. 1-77 : 46-47

Agapetus walkeri (Betten and Mosely)

Fig. 29a, 29b, 29c . Map 29

Synagapetus walkeri Betten and Mosely 1940: 8

Type locality, St. Martin’s Falls, Albany River, Hudson Bay, Ontario, Canada. ( BMNH)

Agapetus rossi Denning 1941: 200 new junior subjective synonym

Type locality, Lake Superior at mouth of Gooseberry River, St. Louis Co., MN. ( USMP)

Diagnosis. The slender ventral arms of X that diverge distally to a transverse terminal denticle or group of denticles are shared by A. hessi , A. kirchneri , and A. spinosus . Differs from A. kirchneri in lacking sclerotized posteriodorsal areas of X and a darkened ventral row of denticles on inferior appendages. Differs from A. hessi in having a single terminal denticle (2 in A. hessi ) on inferior appendage. Differs from A. spinosus in having ventral arms of X with a single terminal denticle, occasionally two (five or more denticles in A. spinosus ), and in having a prominent denticle laterally on each arm of X at 0.2 times length of X (these denticles usually lacking in A. spinosus ).

Description. Male. Length 5.4-6.1 mm (n = 8). Male genitalia: Lateral view ( Fig. 29a ), segment IX with anterior margin thickened, sloping down and forward at 35 o to midline, then sloping posteriad at about 10 o from vertical to 3/4 depth, then sloping posteriad at 45 o to convex ventral margin; dorsal margin very abbreviated, its posterior boundary not apparent; posterior margin slopes down and back at 30 o from horizontal to upper base of preanal appendage, then sloped down and forward at 10 o from vertical to ventral margin; anterior 1/4 of preanal appendage covered by IX. Preanal appendage with straight or concave ventral margin, convex dorsal margin, tip with ventral corner produced, length 4 times depth, extending about halfway to end of X, with about 15 long, erect setae dorsally on exposed portion. Segment X with ventral arms heavily sclerotized, thickest at base, distally about as thick as preanal appendage; abruptly bent near middle, with posterior 1/2 sloped upward at 20 o from basal 1/2; tip with transverse black denticle with 1-2 points, perpendicular to body axis; a triangular denticle present on dorsal surface of ventral arm at level of posterior margin of IX. Remainder of X lightly sclerotized anteriad, especially on dorsal margin, then gradually becoming membranous posteriad; dorsal margin a straight continuation of upper posterior margin of IX on basal 2/3, then abruptly (130 o) sloping down and back to tip of ventral arm. Inferior appendage length = 1.8 times depth; deepest at 3/4 length; dorsal and ventral margins divergent, ventral margin slightly concave near mid-length, length = 0.8 times length of X. End of inferior appendage with triangular dark spot at mid-depth representing inward directed denticle, tip of denticle typically not visible in lateral view, margin slightly concave above denticle, convex below denticle, both dorsal and ventral “corners” rounded. A carina present at mid-depth on outer margin of inferior appendage from base to 3/4 length.

Dorsal view ( Fig. 29b ). Anterior margin of IX broadly concave and apparently contacting or nearly contacting obscure posterior margin. Preanal appendages concave on outer surface, smoothly curved laterad through angle of 45 o to nearly 90 o, margins parallel to convergent basally and distally, tip bluntly pointed. Dorsal, sclerotized portion of X scarcely apparent; ventral arms convergent on basal 1/2 and nearly in contact at mid-length, typically with dark, transverse denticle at 1/4 length; distal 1/3 curves increasingly outward through 60-90 o to terminate in darkened denticle (occasionally bifid) with slightly bulbous base.

Ventral view ( Fig.29c ). Anterior margin of IX broadly and shallowly concave; posterior margin forms obtuse angle (100 o) between inferior appendage bases; depigmented triangle in area posterior to line slightly forward of inferior appendage bases; a transverse row of setae at anterior edge of depigmented area. Inferior appendages with bases swollen, outer margin slightly sinuous, convex and convergent on distal 1/3 to darkened, in-pointed, terminal denticle; inner margins nearly in contact at base, then slightly divergent to 2/3 length, then convex and more divergent to tip.

Larva. Sclerites straw-yellow with brown darker markings typical for genus. Frontoclypeus with four evenly spaced pairs of brown muscle scars arranged in two longitudinal rows on middle 1/3-1/2 of sclerite, anterior three pairs rounded, posterior pair transversely elongate; anterior pair at anterior margin, next pair between eye spots, third pair at widest part of sclerite, posterior pair at 3/4 length of sclerite; two additional rounded brown muscle scars laterally between posterior two pairs, and on midline between middle pairs; a crescent shaped brown mark on midline between posterior pairs of muscle scars. Genae with about 5 rows of 3-6 rounded, brown muscle scars behind eye from level of mandibles to near vertex, with 3 regular, closely spaced rows below eye (area immediately behind eye lacking muscle scars), and 2 irregular rows above eye. Pronotum with about 12 large brown muscle scars on each side, on posterior 1/3 of sclerite and laterally extending forward to area of leg articulation. Muscle scars easily visible on larvae and MMT sclerites. On MMT sclerites, linear brown area margining posterior 1/2 of frontoclypeus extends across suture to adjacent area of genae.

Emergence dates. 24 April-7 September.

Distribution. AL Bibb, Calhoun, Clay (4), Cleburne (8), Lawrence (6), Shelby, Talladega (2), Tallapoosa, Winston (4). CT Fairfield (2), Middlesex (2), Tolland, Windham. GA Dade, Murray (2). MA Franklin (2), Worcester. MD Harford. ME Penobscot, Aroostook. MN Cook (4), Lake (2), St. Louis. NB Charlotte (2), Northumberland, Victoria. NC Burke (3), Caldwell (3), Durham (2), Montgomery (2), Moore, Person, Rutherford, Transylvania (3). NH Carroll (2), Coos, Grafton (2), Hillsborough (3), Merrimack, Strafford (6). NS Inverness. ON Costello Lake, Algonquin Park. PA Cameron, Crawford, Lycoming, Potter, Tioga, Warren. SC Oconee. TN Anderson, Blount (8), Overton, Polk (4), Robertson. VA Bath, Bland (2), Botetourt, Fairfax (3), Hanover, Shenandoah (3), Tazewell. WV Braxton, Hampshire, Pocahontas (4).

Discussion. The female type of A. rossi , in the British Museum, was examined by Ross (1956), and he gave no indication of a generic misidentification, in spite of its occurrence well to the north of other Agapetus species of central North America. We were able to examine the type in 2006, and consider Agapetus rossi Denning, 1941 to be a junior synonym of A. walkeri . The larva illustrated in Wiggins (1977, 1996) very likely represents this species. We have examined adults from MN to eastern NC to AL, and larvae from AL, GA, NC, TN, and VA, and have not noted regional variation. Taken with A. flinti , A. iridis , A. pinatus , A. tomus , and A. vireo .

Etymology. Named in honor of Francis Walker, early trichopterist at the British Museum.

Figures

Figure 28-29. Agapetus spp. male genitalia. 28) Agapetus vireo Ross. 28a, lateral view; 28b, dorsal view, inferior appendages not shown; 28c, ventral view of IX and inferior appendages. 29) Agapetus walkeri (Betten and Mosely). 29a, lateral view; 29b, dorsal view; inferior appendages not shown; 29c, ventral view of IX and inferior appendages.