Agapetus aphallus Etnier, Baxter, and Parker, 2010

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 : 5-7

Agapetus aphallus Etnier, Baxter, and Parker new species

Fig. 2a, 2b, 2c . Map 2

Type material. Holotype, female, length 5.5 mm, EX UT 1.980 . Little Duck R. at TN 55 , 35.4805 o N, 86.0793 o W, Manchester, Coffee Co., TN, 10 May 2005, emerged 23 May, D. A. Etnier. ( NMNH)

Paratopotypes, all EX UT 1.980 . 1 female MMT each to CASC, CUAC, INHS, ROME, SCHC, UMSP, and NMNH ; 1 remains in UT 1.980 , emerged 18 May-8 June .

Additional paratopotypes, all EX UT 1.491. Little Duck R. at TN 55, Manchester, Coffee Co., TN, 1 April 1999, UT Aquatic Insects class. One larva each to CUAC, INHS, ROME, and NMNH.

Additional material examined. TN, Cannon Co.: UT 1.421 , Cavender Br. 0.1 rd mi n of TN 53 on Cavender Road, n of Woodbury, 24 May 1998, 3 larvae /prepupae, 11 female mature pupae/adults ; UT 1.423 , Connell Cr. along TN 53 , 2.4 rd mi s of DeKalb County line, 24 May 1998, 4 larvae /prepupae, 11 female mature pupae/adults ; UT 1.502 , same site, 9 May 1999, 27 female mature pupae/adults. Cheatham Co.: UT 1.805 , Sycamore Cr. 0.8 rd mi se of TN 49 on Old Clarksville Road, 18 April 2002, 2 larvae, 9 female mature pupae/adults ; UT 1.806 , Spring Cr. at Old Clarksville Road, 1.7 rd mi nw of TN 49 , 18 April 2002, 3 larvae /prepupae, 13 female mature pupae/adults. Clay Co.: UT 1.428 , Trace Cr. at jct. Clementsville Kentucky Road and Grady Cherry Road, Oak Grove, 30 May 1998, 12 larvae /prepupae, 9 female mature pupae/adults ; UT 1.642 , same site, 13 May 2000, 4 larva /prepupae, 26 female mature pupae/adults ; UT 1.636 , Wet Mill Cr. trib. at Wet Mill Cr. Road near Overton County line, 13 May 2000, 1 larva, 9 female mature pupae/adults ; UT 1.637 , Wet Mill Cr., ford on private drive 0.9 rd mi from Wet Mill Cr. Road, near Overton County line, 13 May 2000, 4 larvae /prepupae, 11 female mature pupae/ adults ; UT 1.639 , Sweetwater Cr. at jct. Boles Road and Paul Reecer Road, 13 May 2000, 8 female mature pupae/adults ; UT 1.640 , creek at Old Mulkey Road 0.7 rd mi n of jct. Clementsville Kentucky Road, 13 May 2000, 8 larvae / prepupae, 11 female mature pupae/adults ; UT 1.641 , Hurricane Cr., Clementsville Kentucky Road at Clementsville Church of Christ , 0.3 rd mi e of Line Cr. Road, 13 May 2000, 14 female mature pupae/adults ; UT 1.1011 , Little Proctor Cr. at jct. Proctor Cr. Road and Old Watson Road, 13 May 2000, 1 female pupa ; UT 1.1046 , Little Trace Cr. at TN 52 , 13 May 2000, 3 female mature pupae/ adults. Coffee Co.: UT 1.491 , Little Duck R. at TN 55 , Manchester , 11 April 1999, 10 female mature pupae/adults. DeKalb Co. : UT 1.422 , Dry Cr. trib., Dry Cr. Road 0.5 rd mi above Pea Ridge Road , 24 May 1998, 1 prepupa, 3 females. Jackson Co. : UT 1.644 , Pine Lick Cr. at jct. Pine Lick Cr. Road and TN 135 , 13 May 2000, 6 larvae /prepupae, 29 female mature pupae/adults. Macon Co. : UT 1.629 , Spring Cr. at Spring Cr. Missionary Baptist Church , 10 May 2000, 4 prepupae, 15 female mature pupae/adults. Montgomery Co. : UT 1.802 , Camp Cr. at jct. Chapel Hill Road and Seven Mile Ferry Road, s of Cumberland R., 17 April 2002, 6 larvae /prepupae, 12 female mature pupae/adults ; UT 1.803 , Dodson Cr. at Chapel Hill Road, 18 April 2002, 9 larvae /prepupae, 16 female mature pupae/adults ; UT 1.804 , spring run at Hampton Station, ne of Clarksville, 0.5 rd mi e of US 79, 18 April 2002, 12 female mature pupae/ adults. Moore Co.: UT 1.429 , Shipman Cr. 0.2 rd mi below Ledfords Mill on Ledford Mill Road , 24 May 1998, 1 female. Robertson Co. : UT 1.765 , Brush Cr. 100 ft above Ed Ross Road , 16 May 1999, 2 females ; UT 1.801 , Brush Cr. above TN 256 , n of I-24, 17 April 2002, 4 larva /prepupae, 5 female mature pupae/ adults. Sumner Co.: UT 1.538 , Caney Fork Cr. at TN 52 , 28 May 1999, 3 female pupae ; UT 1.1015 , Twin springs at jct. Tyree Springs rd and Ben Albert, 4.0 rd mi s of White House, 16 April 2000, 21 larvae /prepupae, 13 female mature pupae/adults. Williamson Co.: UT 1.344 , Kelly Cr. 0.5 mi above Blowing Springs Br., 12.8 air mi wsw of Franklin , 8 May 1997 and 13 June 2004, female, MMT female ; UT 1.721 , Leipers Fork Cr. at Floyd Road, James K. Angtin Bridge, wsw of Franklin, 19 March and 13 April 2001, many larvae/prepupae, 15 female mature pupae/adults ; UT 1.727 , Pinewood Br. at TN 46 (Pinewood Road), just w of Hillsboro Road, s of Leipers Fork, 13 April 2001, 5 larvae /prepupae, 2 mature female pupae. Wilson Co.: UT 1.565 , Big Springs run just above Cedar Cr., at jct. Old Rome Pike and Big Springs Road, n of I-40, 9 larvae, 21 female mature pupae/adults, 29 April 2000 ; UT 1.631 , Johnson Br. at Big Springs Road, about 0.8 rd mi s of Taylorsville Road, 10 May 2000, 2 prepupae, 10 female mature pupae/adults .

Diagnosis. Differs from all known female Agapetus of eastern and central North America (the female of A. flinti is unknown) in having a steep-sided ventral tubercle ( Fig. 2a, 2c ) on the anterioventral area of segment VIII. This ventral tubercle is clearly visible in ventral view as a U-shaped area, open end anteriad. In the similar female of A. avitus , the ventral tubercle is not apparent in ventral view.

Description. Male. Unknown and possibly non-existent, see Discussion.

Female. Length 5.5-6.3 mm (n = 15). Antennal segments 27. Female genitalia: Lateral view ( Fig. 2a ), ventromedian process sternite VI ventrally projecting, thick and blunt. Segment VIII having ventral tubercle prominent at anterior base, protruding ventrally approximately 1/4 of segment VIII height caudad of tubercle, with sides of ventral tubercle nearly vertical, and with numerous coarse spicules on lateral and ventral surfaces; ventral margin beyond tubercle extending straight to near apex where it becomes desclerotized and difficult to discern in uncleared specimens; anterior margin convex or sinuous, and slanted down and forward to attachment point of ventral apodeme, then slanted down and back at 45 o, its continuation below the apodeme difficult to see. Dorsal margin straight, converging slightly toward ventral margin; posterior margin irregularly sinuous, weakly defined.

Dorsal view ( Fig. 2b ), widest at level of attachment of ventral apodemes, with lateral margins converging posteriad to about 2/3 width of anterior maximum, and with prominent V- or U-shaped emargination, which may have small median projection; anterior margin concave, weakly sclerotized and difficult to differentiate from membranous areas.

Ventral view ( Fig. 2c ), outline as in dorsal view, with posterior emargination deeper. Ventral tubercle with posterior and lateral edges clearly defined and broadly U-shaped, with prominent coarse spicules (not shown, visible at 100X).

Inner cylinder VIII in lateral view occupying much of segment VIII dorsad of ventral tubercle, dorsal and ventral margins straight and parallel, anterior margin rounded, extending anteriad of anterior margin segment VIII as far as anterioventral lobe, and having distinct desclerotized margin extending anteriorly into segment VII; in dorsal and ventral views, anterior margin with deep concavity between large, transparent lobes.

Larva. Head and pronotum light brown, other sclerites pale yellow. Details visible on intact larvae, but more apparent on shed sclerites. Head with oval pale area around eye and pale adjacent to vertex; darker brown muscle scars prominent on posterior 1/2, forming 3 parallel horizontal rows behind eye and scattered elsewhere. Frontoclypeus with irregular pale spot larger than eye spot posteriolateral to each eye, and with 3 closely approximated muscle scars in transverse row on middle of posterior 1/2 of sclerite. Pronotum with posterior 1/2 covered with brown muscle scars with pale centers; posterior 1/2 paler than anterior 1/2. Mesonotal sclerites each with 1-2 brown freckles laterally. Metanotal sclerites same color as freckles, thus darker than adjacent membrane. Weak brown freckles on legs. Prosternal sclerite dark brown, lateral margin slightly shorter than mesal margin. Mesosternal sclerites tan. Legs, sterna, and sclerites on IX and X otherwise typical for genus.

Emergence dates. TN, 19 April-late June.

Distribution. TN, virtually restricted to the Nashville Basin physiographic province, and probably extending into the Basin in south-central Kentucky. Cannon (3), Cheatham (2), Clay (8), Coffee (2), DeKalb, Jackson, Macon, Montgomery (3), Moore, Robertson (2), Sumner (2), Williamson (3), Wilson (2). Edwards’ (1966) record of A. avitus from “Coffee Co., Duck River at Manchester,” based on 3 larvae, presumably represents A. aphallus .

Discussion. Our extensive holdings of this species (29 lots, 27 localities, 348 female pupae/adults) resulted from our efforts to secure males. None was found, and because obtaining specimens from rearing pupae can hardly introduce a sexual bias, it appears that this is an all-female species. In Psychomyia flavida Hagen (Psychomyiidae) and Apatania zonella (Zetterstedt) (Apataniidae) , females typically outnumber males, and there are numerous populations or large collections from which males are unknown. Corbet (1966) discusses these two species plus the hydropsychid Amphipsyche senegalensis (Brauer) from Lake Victoria, Uganda, Africa, as potentially parthenogenetic species under certain circumstances, but males are known for all three species. This may turn out to be the situation in Agapetus aphallus . Based on larval and female similarities with A. avitus , we consider these to be sister species. Agapetus aphallus is primarily a species of the Nashville Basin physiographic province, with outliers in the Barrens Plateau (Highland Rim province) and Ridge and Valley province, while A. avitus has a curious circular distribution around the Nashville Basin on the Highland Rim proper. They are known to co-occur in Montgomery and Moore counties, TN. In Montgomery Co. A. aphallus is known from the eastern portion of the county, and A. avitus only from the northwestern portion; in Moore Co. the A. aphallus record is only 5 air miles ne of an A. avitus locality. Agapetus lots from the Nashville Basin area in which females outnumber males are likely to yield additional specimens of the distinctive female of A. aphallus . The very unexpected find of a MMT female in Pope Cr., Dade Co., GA, (Ridge and Valley province, not included in distribution because of possible locality confusion) suggests that with our capability of recognizing the distinctive larva and female, additional localities outside of the Nashville Basin may be found. We have taken A. gelbae , A. ibis , A. stylifer , and A. tomus with A. aphallus .

Etymology. aphallus = lacking a phallus, in reference to the apparent lack of males in this species.

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.