Agapetus vireo Ross

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 : 44-45

Agapetus vireo Ross

Fig. 28a, 28b, 28c . Map 28

Agapetus vireo Ross 1941: 43

Type locality, Swamp Cr. 7 mi s of Dalton, Whitfield Co., GA. ( INHS)

Diagnosis. Shares with A. crasmus , A. diacanthus , A. gelbae , A. meridionalis , and A. tomus the heavily sclerotized ventral and posterior portions of segment X. Differs from all of these except A. meridionalis in having the preanal appendage subcircular in lateral view, with length 1.5 times depth (versus digitiform, with length 2 or more times depth), and in having the inferior appendages ovoid (versus rhomboid in A. crasmus and A. diacanthus , with posteriodorsal projection in A. gelbae , and with concave or truncate tip in A. tomus ). Posterioventral aspect of X (lateral view), which forms a right angle in A. vireo , is smoothly curved to form a hook in A. crasmus , has a bluntly pointed posteriodorsal projection in A. diacanthus and A. gelbae , and has a rounded ventral lobe in A. tomus . Most similar to A. meridionalis (see Discussion); in A. vireo (lateral view) posterior margin of X vertical and with its posterioventral angle not produced, not extending below the ventral margin of X, and not extending to posterior end of the inferior appendage; in A. meridionalis posterior margin of X sloping down and back at 30 o from vertical, extending below ventral margin of X, and extending posteriad past end of inferior appendage. In addition, there is an arc of 5-10 or more denticles on the inferior appendage in A. vireo , while this same area is occupied by only 3 (occasionally 4) well separated denticles in A. meridionalis .

Description. Male. Length 4.2-5.7 mm (n = 11). Male genitalia: Lateral view ( Fig. 28a ), segment IX with anterior margin thickened, sloping down and forward at 60 o to midline, then nearly straight to convex, sloping down and back at 75 o, to convex ventral margin; dorsal margin straight, forming obtuse angle with upward sloped dorsal margin of X, 2/3 length of ventral margin; posterior margin convex and sloping down and forward at 85 o. Preanal appendage with straight or concave ventral margin, convex dorsal margin, tip rounded, length 1.5 times depth, extending about halfway to end of X, with 6-8 long, erect setae dorsally. Segment X heavily sclerotized along ventral and posterior margins, sclerotized but less heavily so elsewhere. Posterioventral corner of X forming a right angle, transverse denticle projects outward and visible only as a dark corner; posterior margin ends dorsally in a protruding sharp denticle; membranous area medial to lateral plates of X visible dorsally. Inferior appendage length = 2.1 times depth; ovoid, with ventral and dorsal margins slightly convex and tip symmetrically to slightly asymmetrically rounded, extending slightly past X. Denticles near tip of inferior appendage visible as darkened areas on distal 1/2 of ventral margin and extending dorsad submarginally along lower posterior margin; submarginal denticle at posteriodorsal “corner” most prominent.

Dorsal view ( Fig. 28b ). Anterior margin of IX with broad U-shaped emargination, posterior margin weakly separated from X, slightly concave between sides of X and preanal appendages; longitudinal ridge on midline. Preanal appendages parallel sided and nearly straight basally, slightly expanded distally, tips rounded. Segment X dorsally with sclerotized inner margins having narrowly U-shaped junction at base, then slightly divergent to posteriodorsal denticles; area between lateral sclerotized plates of X membranous. Posterioventral angle of X with short, sharp denticle directed laterad perpendicular to body axis; posteriodorsal denticle nearly vertical, protruding posteriad slightly. Distal denticle of the inferior appendages (not shown) sharply pointed, darkened, and transverse.

Ventral view ( Fig. 28c ). Anterior margin of IX barely concave; posterior margin forming 100-120 o angle between bases of inferior appendages; transverse row of setae just anterior to bases of inferior appendages delimits triangular, depigmented area on posterior 1/3 of segment. Inferior appendages with bases angular, outer margins nearly straight, parallel; inner margins straight, nearly in contact at base, divergent from each other at about 40 o to basal dark denticle at middle of appendage, then more divergent and concave to tip of appendage. From large basal denticle a darkened ridge, broken up into small denticles, continues along the ventral margin to posterioventral “corner” where 1 or 2 slightly larger denticles occur; smaller, more widely spaced denticles continue, submarginally, to near base of large denticle near posteriodorsal corner. Ventral arms of X (not shown) converge from base, nearly meeting at 1/3 length, where they are thickest, then diverge to denticle at posterioventral corner.

Larva. Currently not separable from that of A. meridionalis .

Emergence dates. 11 April-10 June, 9 September.

Distribution. AL DeKalb (4), Jackson (3). GA Catoosa (3), Dade, Floyd, Murray (2), Walker (2), Whitfield (2). TN Bledsoe (3), Bradley (4), Cumberland (2), Hamilton (4), Marion (2), Overton (2), Polk, Rhea (2).

Discussion. At two localities from near the A. vireo type locality, from Floyd Co. (UT 1.455, Pocket Cr. at Everett Springs Road 7.3 rd mi s of GA 136), and Walker Co. (UT 1.452, Everett Springs Road 2.7 rd mi s of GA 136) specimens collected were somewhat intermediate between A. meridionalis and typical A. vireo . In UT 1.455 the 5 males examined all have the posterior margin of X sloping down and back and acutely pointed at the posterioventral corner (in A. vireo vertical posterior margin of X forms blunt right angle with ventral margin of X); these differ from the A. meridionalis types in that the posterioventral corner does not extend below the level of the ventral margin of X and does not extend posteriad to the end of the inferior appendage. In UT 1.452 the 9 males examined vary from rather typical A. vireo (1), to resembling males in UT 1.455 (2), to having the posterior margin of X vertical but concave with the posterioventral corner produced into an acute point (2), to being rather intermediate between A. vireo and the two other morphs mentioned in this lot. In UT 1.450 (Walker Co., West Armuchee Cr. at Armuchee Road, 0.2 rd mi s of GA 136) the 4 males examined are typical of A. vireo except the right angle at the posterioventral corner of X is sharply rather than bluntly pointed. Examination of all males in the 4 lots involved indicates no variation in segment X in the 6 A. meridionalis males, and none of the 18 “ A. vireo ” males examined from UT 1.450, UT 1.452, and UT 1.455 approaches A. meridionalis in ventral projection and length of segment X. All 5 males examined from UT 1.484 (Whitfield Co., Vermeil Spring Branch at GA 2, Vermeil, 17 miles north of the A. meridionalis type locality) are typical A. vireo . What appears to be an additional character separating the two species (see Diagnosis) involves denticulation of the inferior appendages. Additional examination of specimens from this portion of Georgia is certainly warranted. We have taken A. vireo with A. avitus , A. ibis , A. iridis , A. tomus , and A. walkeri .

Etymology. Unknown.

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.