Agapetus medicus 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 : 29-30

Agapetus medicus Ross

Fig. 18a, 18b, 18c . Map 18

Agapetus medicus Ross 1938: 107

Type locality, McFadden Springs (Three Sisters Springs), Lake Ouachita State Park, Garland Co., AR. ( INHS)

Diagnosis. The elongate, nearly rectangular, parallel-sided inferior appendage (lateral view) of A. medicus is shared only with A. iridis . In both these species the posterioventral corner of the appendage extends farther posteriad than the posteriodorsal corner. In other Agapetus species of the area covered that could be construed as having a subrectangular inferior appendage, the tip of the appendage is symmetrically rounded or the posteriodorsal corner extends farther posteriad than the posterioventral corner. Differs from A. iridis in having only a terminal denticle per inferior appendage (terminal and subterminal denticles in A. iridis ), and in having length of inferior appendage less than 4 times depth (4.5 or more times depth in A. iridis ).

Description. Male. Length 4.5-6.3 mm (n = 12). Male genitalia: Lateral view ( Fig. 18a ), segment IX anterior margin angles down and forward at 50 o to mid-depth, then smoothly rounded and angling down and back at 60 o to convex ventral margin; posterior margin angles down and back at 30 o to slight shoulder above dorsal margin of preanal appendage, then vertical and smoothly convex to near ventral margin. Preanal appendage clavate, narrow at base, ventral tip produced; basal 1/4 concealed under posteriodorsal shoulder of IX, maximum depth 1/4 of exposed length, length 2/3 times length of X; dorsal edge with 10- 15 erect setae. Ventral arms of X thickest at base, heavily sclerotized; basal 1/3 horizontal to sloping down and back, forming a 135 o angle with thinner, upturned, distal 2/3. Posterior margin of X also heavily sclerotized, perpendicular to distal portion of ventral arm, often slightly serrate on its upper 1/3, and terminating in a denticle perpendicular to posterior margin. Remainder of sides of segment X lightly sclerotized except for membranous area along dorsal margin; length of X 3/4 length of inferior appendage. Length of inferior appendage 3.6 times depth; ventral and dorsal margins nearly straight, parallel; posterior margin slopes down and back from rounded posteriodorsal corner at 15 o from vertical to more angular posterioventral corner; submarginal to marginal posterioventral denticle apparent as a darkened area, with darkened area continuing near posterior margin to just above mid-depth.

Dorsal view ( Fig. 18b ). Segment IX with both anterior and posterior margins concave, posterior margin not apparent near midline where continuous with X. Segment X widest at base; sides slightly convergent posteriad, separated by membrane about to level of distal denticle on inferior appendage; outer base of X often with patch of small, darkened denticles. Preanal appendages with margins nearly parallel, outer margin concave, inner margin convex, curved out and back at about 45 o from body axis. Inferior appendage with transverse, sharply pointed, darkened denticle near tip.

Ventral view ( Fig. 18c ). Anterior base of IX slightly concave, posterior base produced between inferior appendage bases to form 140 o angle; depigmented area anterior to angle occupies posterior 1/4 of IX, bounded anteriad by transverse band of setae. Inferior appendages with lateral margin straight to bluntly pointed tip; inner margins nearly in contact on basal 1/2 to diverging from each other at about 30 o, then diverging from each other at 90 o, concave, and nearly parallel to body axis near base of prominent, transverse, subterminal denticle.

Larva. (Based on sclerites from INHS 27225, no larvae seen). Head and notal sclerites tan. Genae paler on posterior 1/2, with area behind eye covered with inconspicuous pale muscle scars, those near concavity of posterior margin larger, more conspicuous, and less circular. Frontoclypeus with 2 pale, transverse ovals at mid-length (just anterior to lateral angles of sclerite), each extends from lateral margin 1/3 distance to opposite margin; middle of posterior 1/2 of sclerite with about 3 large, pale muscle scars, and remainder of posterior 1/2 with additional, similar but smaller muscle scars. Pronotal sclerites slightly paler on posterior 1/4, with large but inconspicuous muscle scars along outer 2/3 of posterior margin.

Emergence dates. 15 April-5 June.

Distribution. AR Benton, Clark, Garland (11), Hot Spring, Montgomery (13), Polk (9), Saline (11).

Discussion. There appears to be considerable variation in inferior appendages in shape (ventral view) and in the position of the single denticle (terminal to markedly subterminal). In segment X we noted variation in the presence or absence of a patch of small denticles at the base of the segment (dorsal view), the degree of serration of the posterior margin, the orientation of the denticle at the posteriodorsal corner, and the sharpness of the posterioventral denticle of the inferior appendage.

Etymology. Not given in the original description, but likely from the Latin medicus = doctor or physician, in reference to the supposed curative powers of the Three Sisters Springs.

Figures

Figure 16-18. Agapetus spp. male genitalia. 16) Agapetus jocassee Morse. 16a, lateral view; 16b, dorsal view; 16c, ventral view of IX and inferior appendages. 17) Agapetus kirchneri Parker, Etnier, and Baxter. 17a, lateral view; 17b, dorsal view; 17c, ventral view of IX and inferior appendages. 18) Agapetus medicus Ross. 18a, lateral view; 18b, dorsal view; 18c, ventral view of IX and inferior appendages.