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Texas alderflies (Megaloptera: Sialidae): new records, distributions, and a key to adults in Texas.

Megalopterans are among the most primitive of winged insects in the world (Aspock et al., 2001) and include two families: Corydalidae (dobsonflies and fishflies) and Sialidae (alderflies). Sialids are widely distributed throughout the world, although most occur in the Holarctic region. They commonly are called alderflies because in temperate regions they often rest on alders (or other vegetation) growing adjacent to streams or lakes. Previous studies of alderflies in Texas include those of Ross (1937), Tarter et al. (1978), Locklin et al. (2006), and Locklin (2007). However, these studies were not inclusive of all species currently known from the state, or they were ecological in nature.

The family Sialidae includes 10 (extant and fossil) genera worldwide (number of species in parentheses; J. D. Oswald, http://Iacewing.tamu. edu/): Austrosialis (2), Dobbertinia (1), Eosialis (1), Indosialis (3), Leptosialis (1), Nipponsialis (1), Proindosialis (1), Protosialis (14), Sialis (62), and Stenosialis (2). The only genus that occurs in the United States and Canada is Sialis, which also is distributed throughout Europe, Egypt, Japan, and China (Whiting, 1994; Hayashi, 1997; Liu and Yang, 2006). There are 24 species in North America, four of which previously have been reported from Texas (Ross, 1937; Townsend, 1939; Flint, 1964; Tarter et al., 1978; Whiting, 1991 a, Locklin, 2007). These include three species from the infumata group (Sialis velata, S. itasca, and S. mohri), and a single species from the americana group (S. americana). Sialis vagans is reported from Texas for the first time in this paper. In addition, there are several locations where unidentified larvae of Sialis have been collected in Texas (Table 1), indicating that the distribution of some of these or other species in the state may be broader than previously thought. Based on distributions of two additional species, S. infumata and S. joppa, in Oklahoma and Arkansas, it is possible that these two species may be collected eventually in Texas as well.

Texas has a wide variety of environments that are determined primarily by climate and topography. A strong east-to-west moisture gradient is a dominant influence on floral and faunal distributions across the state. The divisions of Texas into biotic provinces by Dice (1943) and Blair (1950) are based on topographic, climatic, thermal, edaphic, and geologic differences. Their seven biotic provinces in Texas are the Austroriparian, Balconian, Chihuahuan, Kansan, Navahonian, Tamaulipan, and Texan (Fig. 1). To date, alderflies have been reported only in three of these seven provinces: Austroriparian, Balconian, and Texan. The Austroriparian Province contains at least three species of alderfly; S. itasca, S. mohri, and S. vagans. Many small streams and ponds are found throughout the province where annual precipitation ranges from 1.03 m near Palestine to 1.43 m in Beaumont. Sialis mohri was collected from lentic systems, whereas S. itasca and S. vagans were collected in small lotic systems. The other two provinces, Texan and Balconian, include much of central Texas, and their shared border is defined by the Balcones fault zone. The Balconian province encompasses the Edwards Plateau region and is primarily Cretaceous limestone. Several springs, rivers, and their tributaries flow southeastward through this province. Sialis itasca and S. velata have been collected in the Texan and Balconian provinces, and S. americana in the Texan province (D. C. Tarter, pers. comm.). Whiting (1991 b) determined that S. itasca and S. velata are sister species. Adults of these two species have been collected concurrently from two sites (Lady Bird Lake, Travis County; San Gabriel River, Williamson County; Locklin et al., 2006). A few males (ca. 4) from these sites exhibited mixed genitalic characteristics of S. velata and S. itasca, suggesting the possibility of hybridization. However, because megalopterans commonly exhibit some degree of phenotypic (including genitalia) plasticity (Bowles and Mathis, 1992), it is not clear whether these specimens represent true hybrids or intraspecific variants.


The following key includes all species of alderflies reported from Texas with terminology from Contreras-Ramos (2006). Sialis velata and S. itasca are sister species and their females lack sufficient, distinct morphological characteristics to be distinguished.
Key to adult alderflies of Texas (modified
from Ross, 1937):

1a. Abdominal apex without ovipositor
(male) (Figs. 2a-2h) 2

1b. Abdominal apex with ovipositor (female)
(Figs. 3a-3d) 6

2a. Ninth sternite covering most of the
genitalia (Fig. 2a); genitalia as in Fig.
2f Sialis vagans Ross

2b. Ninth sternite not covering most of the
genitalia (Figs. 2b-2c) 3

3a. Tenth sternite produced at apex into a
pair of long, converging processes
(Fig. 2h) Sialis mohri Ross

3b. Tenth sternite without long processes 4

4a. Legs with femora reddish-brown, tibiae
redish brown or blackish; head with
distinct red/orange bands extending to
pronotum; gentitalia as in Fig. 2g Sialis
americana (Rambur)

4b. Legs black, or with tibiae slightly paler
than femora; head entirely black without
red/orange bands 5

5a. Ventral lobe of tenth sternite as thin as
the base of dorsal lobe; tenth tergite as
long as tenth sternite is high (Fig. 2d);
ninth gonostyli broadly rounded posteriorly
(Fig. 2b) Sialis velata Ross

5b. Ventral lobe of tenth sternite markedly
robust compared with dorsal lobe; tenth
tergite shorter than tenth sternite is high
(Fig. 2e); ninth gonostyli tapering posteriorly
(Fig. 2c) Sialis itasca Ross

6a. Eighth sternite narrow and divided
medially into two lobes (Fig. 3a) Sialis
vagans Ross

6b. Eighth sternite wide or not divided into
two lobes 7

7a. Ninth sternite distinctly triangular and
sclerotized (Fig. 3b) Sialis mohri Ross

7b. Ninth sternite not triangular or sclerotized 8

8a. Legs with femora reddish-brown, and
tibiae reddish-brown or blackish; eighth
sternite elliptical (Fig. 3c) Sialis
americana (Rambur)

8b. Legs black, or with tibiae slightly paler
than femora; eighth sternite crescentic
(Fig. 3d) Sialis itasca Ross, Sialis velata Ross

North American and county records for Texas follow (Ross, 1937; Tarter et al., 1978; Whiting, 1991b): (a) indicates a new county record in Texas; (b) indicates a new record for Texas.

Sialis itasca Ross--Sialis itasca ranges from 98[degrees]W to the east coast and from 45 to 30[degrees]N. It has been collected from the following counties in Texas: (a) Anderson, (a) Angelina, Brazos, (a) Denton, (a) Gonzales, Jefferson, Limestone, Travis, and Williamson. Other records in North America are: CANADA: Ontario, Quebec. USA: Arkansas, District of Columbia, Georgia, Illinois, Indiana, Kansas, Maryland, Michigan, Minnesota, Missouri, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Tennessee, Virginia, West Virginia, and Wisconsin.

Sialis velata Ross--Sialis velata is distributed from 116[degrees]W to the east coast and from 58 to 30[degrees]N. County records for Texas are: Bexar, Kerr, Travis, and Williamson. Additional records in North America include: CANADA: Alberta, British Columbia, Manitoba, Ontario, Quebec, Saskatchewan. USA: Colorado, District of Columbia, Idaho, Illinois, Kansas, Kentucky, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nebraska, New Jersey, New Hampshire, New York, North Carolina, North Dakota, Oklahoma, Tennessee, Utah, Vermont, Virginia, West Virginia, Wisconsin, and Wyoming.

Sialis mohri Ross--Sialis mohri ranges from 96[degrees]W to the east coast and from Quebec (specific location not reported) to 31[degrees]N. Records in Texas are from Shelby and (a) Rusk counties and represent the western-most records. Additional records include: CANADA: New Brunswick, Ontario, Quebec. USA: Arkansas, Connecticut, Illinois, Indiana, Kansas, Kentucky, Maine, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Nebraska, New Hampshire, New Jersey, New York, Ohio, Oklahoma, Pennsylvania, Rhode Island, Tennessee, Vermont, and Wisconsin.

Sialis americana (Rambur)--Sialis americana ranges from 96[degrees]W to the east coast and from 43 to 27[degrees]N. The record for Texas is from Dallas County. Other records in North America are: USA: Connecticut, District of Columbia, Florida, Georgia, Indiana, Louisiana, Maryland, Mississippi, Missouri, New Hampshire, New Jersey, Ohio, South Carolina, Virginia, and Wisconsin.

Sialis vagans Ross--Sialis vagans is distributed from 95[degrees]W to the east coast and from Quebec (specific location not reported) to 31[degrees]N. The record for Texas is from Panola County. Other records in North America include: CANADA: New Brunswick, Nova Scotia, Ontario, Quebec. USA: Arkansas, Connecticut, Florida, Georgia, Illinois, Indiana, Kansas, Kentucky, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, New Hampshire, New Jersey, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, Virginia, Vermont, West Virginia, and Wisconsin.


Collection data for the new state record for Texas (S. vagans): Panola County, Socagee Creek at HWY 2517; two females, 16 March 2006, J. L. Locklin; three males, 17 March 2007, J. L. Locklin. All specimens are deposited in the personal collection of the author.

I thank J. D. Oswald for providing specimens from the Texas A&M University Insect Collection, D. C. Tarter for records of adult S. velata and S. itasca, and D. E. Bowles, J. A. Back, and R. S. King for providing larval collection records. I appreciate the comments of D. E. Bowles, E. C. Morgan, D. S. Vodopich, and two anonymous reviewers on early drafts of this manuscript. I also thank E. Salazar for translating the abstract into Spanish.


Submitted 3 October 2007. Accepted 6 May 2008. Associate Editor was Jerry L. Cook.


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BLAIR, W. F. 1950. The biotic provinces of Texas. Texas Journal of Science 2:93-117.

BOWLES, D. E., AND M. L. MATHIS. 1992. Variation in the terminalia of Neohermes concolor with a key to males of Neohermes in eastern North America (Megaloptera: Corydalidae: Chauliodinae). Insecta Mundi 6: 145-149.

CONTRERAS-RAMOS, A. 2006. Protosialis ranchograndis, a new species of alderfly from Venezuela, with a redescription of P. brasiliensis Navas (Megaloptera: Sialidae). Proceedings of the Entomological Society of Washington 108:977-984.

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FLINT, O. S. 1964. New species and new state records of Sialis (Neuroptera: Sialidae). Entomological News 75:9-13.

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LOCKLIN, J. L., T. A. ARSUEEI, AND D. E. BOWLES. 2006. Life history of Sialis (Megaloptera: Sialidae) in a lentic and lotic ecosystem in central Texas. American Midland Naturalist 155:50-62.

ROSS, H. H. 1937. Nearctic alder flies of the genus Sialis (Megaloptera: Sialidae). Bulletin of the Illinois Natural History Survey 21:57-99. [Errata: printed on a free slip of paper inserted in the work.]

TARTER, D. C., W. D. WATKINS, D. L. ASHLEY, AND J. T. GOODWIN. 1978. New state records and seasonal emergence patterns of alderflies east of the Rocky Mountains (Megaloptera: Sialidae). Entomological News 89:231-234.

TOWNSEND, L. H. 1939. A new species of Sialis (Megaloptera: Sialidae) from Kentucky. Proceedings of the Entomological Society of Washington 41: 224-226.

WHITING, M. F. 1991a. A new species of Sialis (Megaloptera: Sialidae) from southern California. Great Basin Naturalist 51:411-413.

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Department of Biology, Baylor University, One Bear Place 97388, Waco, TX 97388

Correspondent: jason
TABLE 1--Locations of collections of larval Sialis in Texas.

 County Stream Biotic province(s)

Anderson Box Creek Austroriparian/Texan
Bell Nolan Creek Balconian/Texan
Bell Salado Creek Balconian/Texan
Bexar Salado Creek Balconian/Tamaulipan
Brazos Navasota River Texan
Cherokee Box Creek Austroriparian
Colorado Cummins Creek Texan
Comal Comal Springs Balconian/Texan
Coryell Plum Creek Balconian/Texan
Dallas Tenmile Creek Texan
Erath North Bosque River Texan
Gregg Rabbit Creek Austroriparian
Hamilton Duffau Creek Balconian/Texan
Hays San Marcos River Balconian/Texan
Houston Dickey Creek Austroriparian
Lampasas Lampasas River Balconian
Lavaca Lavaca River Texan
Leon Buffalo Creek Austroriparian/Texan
Marion Black Cypress Bayou Texan
Menard Ft. McKavett Spring Balconian
Nacogdoches Legg Creek Austroriparian
Panola Mill Creek Austroriparian
San Jacinto Winter's Bayou Austroriparian
Jan Jacinto East Fork San Jacinto
 River Austroriparian
Smith Mud Creek Austroriparian
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Title Annotation:Notes
Author:Locklin, Jason L.
Publication:Southwestern Naturalist
Article Type:Report
Geographic Code:1USA
Date:Dec 1, 2008
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