Agapetus illini 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 : 23-24

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Agapetus illini Ross


Agapetus illini Ross  

Fig. 14a, 14b, 14c View Figure 13-15 . Map 14

Agapetus illini Ross 1938: 106  

Type locality, Herod, Pope Co., IL. ( INHS)

Diagnosis. Shares the upturned, spinose posterior margin of X with A. alabamensis   , A. minutus   , A. ruiteri   , and A. tricornutus   . Differs from A. alabamensis   and A. tricornutus   in having many similar denticles (8-10) versus only 3-9 and irregular in length and spacing in these two species. Differs from both A. minutus   and A. ruiteri   in having two prominent transverse denticles on each inferior appendage (versus only one prominent transverse denticle per appendage in A. minutus   and A. ruiteri   ); in having a row of 2-5 darkened serrations at the anteriodorsal base of the lateral arms of X (versus a triangular lateral projection midway on the sides of X); in having the denticulate posterior margin of X not extending dorsally past the dorsal margin of X (extending well past dorsal margin of X in A. minutus   and A. ruiteri   ); and in having the ventromedian process of VI non-sclerotized ventrally (a character shared only with A. hessi   ). Differs further from A. ruiteri   in having the dorsal setae on the preanal appendage slender (as robust as the denticles on X in A. ruiteri   ).

Description. Male. Length 4.5-8.0 mm (n = 14). Male genitalia: Lateral view ( Fig. 14a View Figure 13-15 ), anterior margin of IX slopes down and forward at 50 o angle to midline, then down and back at 70 o to straight or slightly convex ventral margin; dorsal margin slightly convex, length = 1/3 length of ventral margin; posterior margin angling posteriad at 10-20 o from vertical to midline, then nearly vertical to lower base of inferior appendage. Preanal appendage clavate, maximum depth, near tip, is 1.5 times basal depth, length = 1/2 that of inferior appendage; about 10 long, erect setae on exposed distal 3/4. Segment X sclerotized at base, ventrally, and at posterior margin, with membranous area occupying dorsal 1/2 of segment. Sclerotized ventral arms of X angle down from near base of preanal appendage to form (125 o) angle with remainder of ventral margin, then upturned at about 90 o distally; hind margin convex, and with about 8 short, upturned denticles that are longer and more concentrated near recurved, pointed tip. Dorsal margin of sclerotized sides of X nearly parallel to ventral margin except at tip. Dorsal base of sclerotized portion of X with 2-5 closely spaced serrations. Inferior appendage 3/4 length of X, length = 3 times depth; forming a nearly perfect parallelogram, acute angles about 35 o, basal and posterior edges 5/8 length of dorsal and ventral edges; denticle-bearing, darkened area near posterior margin arcs from posterioventral corner to near dorsal margin (convex distally and diverging from posterior margin); the two denticles prominent in ventral view appear as enlarged areas at each end of the linear darkened area.

Dorsal view ( Fig. 14b View Figure 13-15 ). Anterior margin of IX deeply concave; posterior margin with V-shaped emargination, mid-dorsal suture apparent, mid-dorsal length 1/4 length of preanal appendages. Preanal appendages divergent from body axis at 25 o angle, sinuate, most of inner margin convex, sides parallel, swollen on distal 1/2. Outer margins of ventral arms of X parallel to slightly divergent; mesal margins obscured by membranous area which occupies much of dorsum of X; basal cluster of 2-5 darkened serrations apparent; denticles along recurved distal margin conspicuous. Inferior appendages with pair of transverse denticles conspicuous.

Ventral view ( Fig. 14c View Figure 13-15 ). Anterior margin of IX shallowly concave; posterior margin concave on each side of pointed (90 o angle) projection between inferior appendage bases; depigmented area 1/3 length of IX apparent posteriad. Outer margins of inferior appendages with slight concavity at 2/3 length, tips rounded; inner margins slightly divergent on basal 3/8, then concave and divergent at about 90 o from each other to transverse denticle at 3/4 length of appendage; a slightly smaller denticle at dorsal termination of darkened, denticle-bearing ridge on inner surface of appendage (visible in oblique view). Inner margins of sclerotized arms of X converge from base of preanal appendages, in near contact at basal 1/8, and smoothly divergent to tips.

Larva. Head, notal sclerites, and anal claws gray-brown; other sclerotized areas paler except for usual dark sutures/margins typical for genus. Frontoclypeus with two transverse pale areas at midlength, each 1/3 width of sclerite and extending mesad from near lateral margin. Pale muscle scars on genae and pronotum visible on shed sclerites of MMTs, but not on larvae. Genae with a tight cluster of about five horizontally elongate pale muscle scars at posterior margin behind eye. Posterior 1/4 of pronotum paler, and with 2 poorly developed rows of elongate muscle scars; anterior row with about three scars per side, posterior row with about 8.

Emergence dates. 28 March-20 July, 8 and 23 October.

Distribution. AR Benton, Crawford (3), Faulkner, Franklin (8), Garland, Independence, Johnson (2),Polk (2), Pope, Pulaski (3), Scott, Searcy, Van Buren (2),Washington (9). ID Lincoln. IL Hardin, Herod, Pope (11), Saline (3), Union (2). IN Lawrence. KY Bullitt, Christian (2), Clinton, Fayette (3), Jackson, Jessamine (2), Lincoln (2), Logan, Mercer (2), Pulaski (3), Wayne (2), Whitley, Woodford (2). MO Christian (6), Dade (3), Dent, Douglas (3), Franklin (3), Greene (14), Iron, Laclede, Lawrence, Madison (2), Maries(2), McDonald, Miller, Newton (4), Oregon (5), Polk, Reynolds, Shannon (4), Taney (4), Texas, Washington. OK McCurtain, Delaware (4), Le Flore, Pushmataha. TN Fentress (3), Montgomery (2), Overton (2), Pickett (2).

Discussion. Taken with A. avitus   at numerous localities. This is the only Agapetus   known to occur both east and west of the Mississippi River.

Etymology. Not given in original description, but surely “of Illinois ”, the type locality, possibly with additional implications associated with the University of Illinois sports teams, the “Fighting Illini”.


Illinois Natural History Survey














Agapetus illini Ross

Etnier, David A., Parker, Charles R., John T. Baxter, Jr., Long, Todd M. & Drive, News Sentinel 2010

Agapetus illini

Ross, H. H. 1938: 106