Agapetus crasmus 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 : 12-13

Agapetus crasmus Ross

Fig. 6a, 6b, 6c . Map 6

Agapetus crasmus Ross 1939: 66

Type locality, Martin Springs, Marion Co., TN. ( INHS)

Diagnosis. The inferior appendage, lateral view, forms a nearly perfect rhombus only in this species and in A. diacanthus . Details of the heavily sclerotized ventral arm of segment X are very different in the two species (scoop-shaped in A. crasmus , with short, sharp, upturned terminal and subterminal dorsal denticles separated by a concavity, versus terminal dorsal and ventral denticles separated by nearly vertical, slightly concave, posterior margin of X in A. diacanthus ). In addition, in A. crasmus the internal darkened ridge along posterior margin of inferior appendage has a denticle at the middle of the ridge and one at each end; in A. diacanthus there are only two denticles, one at each end of the ridge.

Description. Male. Length = 4.7-5.9 mm (n = 13). Male genitalia: Lateral view ( Fig. 6c ), anterior margin of IX slopes down and forward at 45 o angle to midline, then convex and sloped down and back at 75 o, to convex ventral margin; dorsal margin straight, 3/4 length of ventral margin, sloping down and back at 20 o angle; posterior margin angles slightly posteriad down to midline, then angled down and forward at 70 o angle to near ventral margin. Preanal appendage subrectangular, 1/2 length of X, length = 3 times depth, 12-15 setae dorsally on entire exposed length. Segment X lateral areas sclerotized throughout, more heavily so on ventral arm, which is nearly horizontal to sloping upward at 15 o. Ventral arm narrowest at base, gradually widening to subterminal dorsal denticle, then concave to terminal denticle; ventral margin straight, convex toward tip which curves dorsad to terminal denticle; area between dorsal denticle and terminal denticle 2/3 preanal appendage length, with tip of terminal denticle and dorsal denticle at about same level. Dorsal margin of X smoothly convex from posteriodorsal corner of IX to tip of subterminal denticle. Inferior appendage nearly a perfect rhombus, horizontal length = nearly 2 times depth; dorsal, ventral, and posterior margins equal, basal margin slightly shorter; acute angles 60 o; ventral margin convex, other margins straight; internal dark ridge visible, parallel to and slightly anterior to posterior margin.

Dorsal view ( Fig. 6b ). Anterior margin of IX deeply concave, posterior margin truncate, mid-dorsal length = 3/4 length of preanal appendage. Preanal appendages with inner margin convex; outer margin parallel to inner margin, tip rounded. Dorsal inner edges of X joined near base, then gently concave to dorsal denticle on ventral arm. Inner margins of ventral arms converge on basal 1/3 to nearly meet, then curved and divergent to bluntly pointed terminal denticle. Inferior appendages with dorsal inner edge concave.

Ventral view ( Fig. 6c ). Anterior margin of IX concave, posterior margin forming 90 o angle between bases of inferior appendages; area posterior to linear transverse row of setae depigmented (posterior 1/3 of segment). Inferior appendages with outer margin nearly straight; inner margin straight, in contact at base, diverging from each other at about 25 o to small denticle at anterior end of biconcave denticulate ridge (posterior margin of appendage); ridge with blunt denticle at about 2/3 length, basally more concave than distally; posteriodorsal end of denticulate ridge often bearing a tiny denticle. Ventral arms of X convergent to 3/8 length, meeting at 20 o angle from each other, then divergent at same angle; distally convex on inner margin to tips of terminal denticle.

Larva. Head and pronotum dusky yellow, other sclerites paler, straw-yellow. Darker markings on sclerites as described for genus. Head may have dark pigment behind eye broken into 2 rows of large spots by paler area, and may have a large brown spot or two on each side of the vertex. Frontoclypeus with a pale area size of eye spot on each side at mid-length; a dark muscle scar often visible at median and posterior margin of each spot; additional dark muscle scars may be visible as one or two transverse rows of 2-3 scars per row across middle of posterior 1/4 of sclerite. Eye spot surrounded by circular pale area. Pronotum with 3-6 large, dark muscle scars on posterior 1/2. Prosternum with inner side 1/2-2/3 length of outer side.

Emergence dates. 17 April-6 June.

Distribution. AL Jackson (14), Madison (4), Marshall (3). TN Franklin (4), Grundy (3), Marion, Van Buren, Warren.

Figures

Figure 4-6. Agapetus spp. male genitalia. 4) Agapetus avitus Edwards. 4a, lateral view; 4b, dorsal view, inferior appendages not shown; 4c, ventral view of IX and inferior appendages. 5) Agapetus baueri Etnier, Parker, and Baxter. 5a, lateral view; 5b, dorsal view; 5c, ventral view, preanal appendages not shown. 6) Agapetus crasmus Ross. 6a, lateral view; 6b, dorsal view; 6c, ventral view, preanal appendages not shown.