Agapetus alabamensis Harris, 1986

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 : 4-5

Agapetus alabamensis Harris

Fig. 1a, 1b, 1c . Map 1

Agapetus alabamensis Harris 1986: 30

Type locality, unnamed tributary to Wallace Branch, 5 mi se of Berry, T 17S, R 10W, S2, Tuscaloosa Co., AL. ( NMNH)

Diagnosis. The numerous sharp denticles on the posterior margin of segment X (lateral view) separates this species from other central and eastern North American species except the illini group ( A. illini , A. minutus , A. ruiteri ), and A. tricornutus . These denticles are small, regular, and numerous in the illini group, typically only 3 in A. tricornutus , and irregular and varying from 4 to 9 in A. alabamensis . Agapetus alabamensis further differs from A. tricornutus in having the posterioventral margin of X down-curved in its distal 1/4 (straight to up-curved in A. tricornutus ).

Description. Male. Length 4.5-6.1 mm (n = 5). Male genitalia: Lateral view ( Fig. 1a ), segment IX anterior margin slants down and forward to below middle at 60 o; lower 1/3 slants down and back at 75 o, slightly convex, to ventral margin; dorsal margin straight, about 2/3 length of ventral margin, sloping down and back at about 10 o; posterior margin concave to upper base of preanal appendage, vertical and convex to inferior appendage base. Preanal appendage clavate, 1/2 length of X, its maximum depth (past mid-length) about 1/4 length; distal 1/2 of dorsal margin and posterior end with about 12 long, erect setae. Sides of X sclerotized, more opaque along ventral arm; dorsal margin slightly concave on basal 7/8, then depressed to base of most anteriodorsal denticle near apex. Ventral margin slopes downward for basal 1/3, then upward to near tip where it is again curved downward. Terminal denticles irregular, 4-9 in number, directed horizontally ventrad, gradually grading to nearly vertical dorsad. Inferior appendage length = 2.4 times depth; dorsal and ventral margins slightly convex, nearly parallel; posterior margin concave and angling down and forward from tip at 60 o. Black submarginal denticle visible on inner surface at posteriodorsal corner; sclerotized ridge at posterioventral corner visible as a dark line.

Dorsal view ( Fig. 1b ). Segment IX with anterior margin concave, its mid-length about 1/2 that of preanal appendages, posterior margin slightly concave, often poorly differentiated from X. Preanal appendages with outer margin straight and parallel to body axis; inner margin convex on distal 1/2; tip pointed. Sclerotized inner margins of X narrowly separated by dorsal membranous area and convergent to V-shaped basal fusion. Dorsolateral margins of X converge slightly from base to tip; ventral arms (not shown on Fig. 1b ) with inner margins strongly convergent on basal 1/4 and divergent on distal 3/4. Dorsal subterminal denticles of X convergent, dorsal terminal denticles of X divergent. Inferior appendages (not shown on Fig. 1b ) with denticle near posteriodorsal margin pointed, transverse.

Ventral view ( Fig. 1c ). Anterior margin of IX concave, posterior margin V-shaped (90-100 o angle) between inferior appendage bases; triangular depigmented area on IX anterior to inferior appendage bases. Inferior appendages with lateral margin swollen near base, then straight and slightly divergent to rounded tip. Inner margins straight and divergent from each other (15 o angle) to just past mid-length, where a tiny dark denticle marks the anterior end of a concave, heavily sclerotized ridge that diverges to the posterioventral angle of the inferior appendage; there it thickens to form another weak denticle; the ridge then abruptly more concave and more divergent nearly to base of submarginal posteriodorsal denticle. Posterioventral tip of X and its denticle-like prolongation (not shown on Fig. 1c ) diverge from body axis at about 45 o.

Larva. Genae and frontoclypeus gray except for pale area around eye. No muscle scars visible on head of larvae; frontoclypeus of MMT with arc of about 7 pale muscle scars extending across sclerite just posterior to lateral angles. Pronotum gray except for paler anterior third; 2 rows of 3 pale muscle scars diverge from each other at 40 o, from middle of segment near midline. Mesonotal and metanotal sclerites paler, the former slightly darker at anteriolateral corners, occasionally difficult to differentiate from adjacent membrane. Legs, sterna, and sclerites on IX and X typical for genus.

Emergence dates. 11 April-6 May.

Distribution. AL Blount (4), Cullman (2), Etowah (2), Fayette (2), Lawrence, Tuscaloosa (2).

Discussion. As is the case for A. meridionalis and A. vireo , and A. pegram and A. stylifer , Agapetus alabamensis and A. tricornutus appear to be closely related. We have seen considerable variation in the number of denticles on segment X in A. alabamensis , but nothing of that sort in A. tricornutus . The only other character that appears to be diagnostic for males (see diagnosis) involves the shape of the ventral margin of X. Other subtle differences in the male descriptions may be specimen- or population-based rather than species-based. Additional study of males in this portion of Alabama is certainly warranted.

Etymology. alabamensis = of Alabama.

Figures

Figure 1-3. Agapetus spp. genitalia. 1) Agapetus alabamensis Harris, male genitalia. 1a, lateral view; 1b, dorsal view, inferior appendages and ventral portion of X not shown; 1c, ventral view of IX and inferior appendages. InfApp = inferior appendage; PrApp = preanal appendage; IX = segment IX; X = segment X. 2) Agapetus aphallus Etnier, Baxter, and Parker, female genitalia. 2a, lateral view; 2b, dorsal view; 2c, ventral view. 3) Agapetus artesus Ross, male genitalia. 3a, lateral view; 3b, dorsal view; 3c, ventral view of IX and inferior appendages.