Smicridea (Smicridea) fasciatella McLachlan 1871

Smicridea (S.) fasciatella McLachlan

Smicridea fasciatella McLachlan, 1871:136.—Milne, 1936:72, 73.—Ross, 1944:85.—Kimmins and Denning, 1951:116.—Kimmins, 1957:106.—Fischer, 1963:132; 1972:144.

Hydropsyche divisa Banks, 1903b:244.

Smicridea divisa (Banks).—Ulmer, 1907b: 175.

Smicridea divisa (Banks) [as synonym of fasciatella].—Milne, 1936:73.—Ross, 1938:19.—Fischer, 1963:133.

This, the type-species of the genus, is common in the southwestern United States and northeastern Mexico. I have examined the type series of H. divisa Banks and concur in its synonymy with S. fasciatella McLachlan. The generic diagnoses of adult, larva, and pupa are based primarily upon this species.

The coloration is sufficient in general for the recognition of the adults of this species. The genitalia of the male are extremely similar to those of the following species, S. varia (Banks), but the apex of the tenth tergite in dorsal aspect is obliquely truncate, and the posterolateral arms of the internal sclerite of the aedeagus are narrow and diverge at right angles from the central axis. The female genitalia do not appear to be distinctive in the two species.

The larvae appear to be identical to those of S. varia, although the shape of the anterior margin of the frontoclypeus and molar tooth of the mandibles will distinguish the known larvae of the other species in the genus. The pupae of all three species known in this subgenus seem inseparable. They may be separated from the pupae of the two known species in Rhyacophylax, by the teeth on 3P which is Smicridea sensu stricto are borne irregularly over its surface rather than in one anterior row.

ADULT.—Length of forewing 6 mm. Color gray, legs pale brown, head with pale hair anteromesally; forewing with 3 transverse, irregular bands of white hair of which the basal and apical bands are rather diffuse, apical fringe white (Figure 19). Male genitalia: Ninth segment with anterior margin nearly vertical. Tenth tergite constricted subapically with tip produced into a dorsal point in lateral aspect, in dorsal aspect with tip obliquely truncate. Clasper with basal segment long, barely expanded apicad; apical segment tapering to a point in dorsal aspect. Aedeagus tubular, with basal and apical sections meeting at an angle of about 130°; internal sclerite narrow, with narrow, laterally directed apical arms. Female genitalia: Eighth sternite with posterolateral lobe narrow, dark fold straight, posterior margin nearly straight. Ninth tergum with anterior margin nearly right angled, nearly vertical below angle. Vagina with lateral and anterior support narrow, central sclerite and opening simple; with a lightly sclerotized pouch arising posteriad.

LARVA.—Length to 9 mm. Sclerites yellowish brown to brown; head with color pattern distinct to very obscure, with a distinct pale, small spot at base of each seta. Anterior margin of frontoclypeus with evenly spaced, rounded lobes. Mandibles with molar tooth produced, with ventral angle of about 90°.

PUPA.—Length 4.5–5.5 mm. See generic description.

MATERIAL.—U.S.A.: COLORADO: Adams County, Watkins, 4–5 July 1927, Cornell University, Lot 542 Sub 300, 1 (CU). OKLAHOMA: Reagan, Pennington Creek, 15 October 1937, K. and R. Weddle, 1 (INHS); same, but 1 June 1937, H. H. Ross, many (INHS). TEXAS: Spring fed stream W of Brackettville, 17 April 1939, H. H. and J. A. Ross, 1 3 pupae; same but 21 September 1960, Flint and Collette, 20 larvae. Gonzales, 12 May 1958, Flint and Evans, 5 4 . Zavalla County, Nueces R., 26 April 1910, Hunter and Pratt, 1 . Nueces R., 5 miles SW of Mathis, 12 August 1963, Duckworth and Davis, many . Mission, Bentsen State Park, 28 September 1951, A. B. Gurney, 1 ; same, but 10–11 August 1963, P. J. Spangler, 2 . Victoria, March 1926, E. A. Schwarz, 1 ; same, but 24 April 1904, H. S. Barber, 3 larvae. Ottine, Palmetto State Park, 12–13 August 1963, P. J. Spangler, many , 2 larvae; same, but 24 September 1960, Flint and Collette, 2 larvae. Del Rio, San Felipe Spring, 21 September 1960, Flint and Collette, 4 2 , 1 larva, 1 pupa. Kerr County, Camp Verde, 9 October 1960, Flint and Collette, many , 15 larvae. San Marcos, San Marcos R., 18 June 1960, O. S. Flint, Jr., 4 larvae, 2 pupae; same, but 21 May 1960, many . Fentress, San Marcos R., 17 September 1960, Flint and Collette, 11 larvae. Martindale Bridge, San Marcos R., 21 May 1960, Flint and Edwards, 5 4 , 13 larvae; same, but 17 September 1960, Flint and Collette, 9 larvae. Bandera, 9 October 1960, Flint and Collette, 2 1 , 7 larvae, 2 pupae. East of Seguin, 17 September 1960, Flint and Collette, 25 larvae; same, but 24 September 1960, 75 larvae. San Geronimo Cr., between Riomedina and Castroville, 10 May 1960, Flint and Collette, 11 larvae. Medina R., below Castroville, 14 May 1960, Flint and Huddleston, 6 larvae, 1 pupa; same, but 8 October 1960, Flint and Collette, many larvae and pupae. Medina R., above Riomedina, 14 May 1960, Flint and Huddleston, 5 1 , many larvae and pupae; same, but 10 May 1960, Flint and Collette, many larvae and pupae. ARIZONA: Salt River, April, Oslar, lectotype H. divisa Banks, lectoallotype, lectoparatype (MCZ). 3 miles W of Quartzsite, 25 July 1952, R. B. and J. M. Selander, 1 (INHS).

MEXICO: TAMAUUPAS: Santa Engracia, 25 April 1936, A. Dampf, 1 (INHS). Ciudad Victoria, 22 March 1963, R. Balderas L., 1 . NUEVO LEON: Rió Elizondo, Monterrey, 19–20 June 1965, O. S. Flint, Jr., l 2 . Rió Camacho, Linares, 21–22 June 1965, O. S. Flint, Jr., many .3 miles E of Galeana, 7–9 August 1963, Duckworth and Davis, 2. SAN LUIS POTOSI: El Salto, 11–14 July 1963, Duckworth and Davis, many ; same, but 23–24 June 1965, O. S. Flint, Jr., 4 4 ; same, but 8 August 1966, many . Tamazunchale, 29 March 1951, Lattin and Walker, many (INHS). 2 miles S of Tamazunchale, 15 July 1963, Duckworth and Davis, many . Rancho Quemado (4 miles S of Tamazunchale), route 85, km 353, 4–6 August 1966, O. S. Flint, Jr., many ; same, but 27 June 1965, 5 1 . 2 miles N of Tamazunchale, 2 August 1963, Duckworth and Davis, 5 11 ; same, but 16–18 July 1963, 15 . Palitla (6 miles N of Tamazunchale), 25 June 1965, O. S. Flint, Jr., many ; same, but 5 June 1966, many ; same, but 5 August 1966, many . Huichihuayan (25 miles N of Tamazunchale), 3–4 August 1963, Duckworth and Davis, many ; same, but 26 June 1965, O. S. Flint, Jr., many ; same, but 4 June 1967, 1 . VERACRUZ: 7 miles SW of Poza Rica, 20–22 July, Duckworth and Davis, 3 18 . Puente Nacional, 31 July 1966, Flint and Ortiz, 2 . SINALOA: 25 miles E of Villa Union, 4 August 1964, 2 (CNC). 21 miles E of Villa Union, 25 July 1964, 3 3 (CNC). JALISCO: 13 miles N of Chapala, 1 August 1963, P. J. Spangler, 1 . La Barca, 2 October 1934, A. Dampf, 16 (INHS).

BIOLOGY.—This is a common and often abundant species in the southwestern United States and northern Mexico. The immature stages are found on rocks and sticks, generally in riffle areas, in flowing water of from a meter to 10–15 meters in width. The larvae construct a typically hydropsychid retreat and net extending into the current. The pupae are generally found in a more protected site enclosed in a shelter of sand and/or organic matter rather solidly held together by silk.

The adults are taken at light, often abundantly, at night.