John C. Abbott

NOTES ON THE DISTRIBUTION OF ODONATA IN THE TEXAS PANHANDLE, WITH A SUMMARY OF NEW STATE AND COUNTY RECORDS

Abstract Previously, no Odonata have been reported from 44 Texas counties (17%), mainly from the northern Panhandle. Adult dragonflies and damselflies collected since September of 1999 are reported from 24 sites in 14 counties throughout the Texas Panhandle. A total of 35 species is discussed, representing 73 new county records and 4 new state records. First records of Odonata are included for 6 counties.

The female of Leptobasis melinogaster González-Soriano (Odonata: Coenagrionidae)

The female of Leptobasis melinogaster González-Soriano, 2002 is formally described and illustrated. Female L. melinogaster can be distinguished from the seven other known congeners by the shape and presence of a ventral lobe below the rounded lateral margins of the posterior and median lobes of the prothorax as well as by the dark apices on the femora.

Odonata (Dragonflies and Damselflies)

Odonata, the order to which dragonflies and damselflies belong, inspire a wide range of emotions ranging from fear to admiration. They are a beneficial group of insects whose primary prey items, as both larvae and adults, include biting flies such as mosquitoes (Culicidae), black flies (Simuliidae), and horse and deer flies (Tabanidae). They also represent important components in the food webs of freshwater systems. Odonata are paleopterous, exopterygote insects whose closest relatives are the Ephemeroptera (mayflies). The larvae are longer-lived than the adults and have evolved numerous adaptations to the freshwater aquatic environment resulting in pronounced differences in form across taxonomic groups. The adults occupy a conspicuous presence in the air, especially around ponds. The group is largely found in warmer areas, with over 75% of its species occurring in tropical regions. Some species, such as Anax junius, are known to migrate and are capable of traveling from Canada to Veracruz, Mexico, though our understanding of exactly what triggers these events, when they occur, and which members in the population are migrating, still remains a mystery.

Development of polymorphic microsatellite markers for a rare dragonfly, Cordulegaster sarracenia (Odonata: Cordulegastridae), with notes on population structure and genetic diversity

We isolated and characterized a total of 13 microsatellite loci from Cordulegaster sarracenia (Odonata: Cordulegastridae). Loci were screened in 24 individuals from Louisiana and Texas. Within C. sarracenia, the number of alleles per locus ranged from 0 to 5, and observed and expected heterozygosities ranged from 0.000 to 0.556 and 0.000 to 0.613, respectively. Overall differentiation among study populations was very high (FST = 0.423), suggesting significant geographic population structure with low diversity within populations. Twelve of the 13 primers amplified in C. sayi, C. diastatops, C. maculata, and C. obliqua and polymorphism levels are reported. These new genetic markers will provide tools for addressing a number of population genetic and demographic questions relating to conservation of this rare dragonfly species.

Description of the nymph of Gomphurus gonzalezi (Odonata: Gomphidae)

Gomphurus gonzalezi (Dunkle) is a locally distributed dragonfly ranging from the Lower Rio Grande in south Texas southward to San Luis Potosi state in northeastern Mexico. We describe and illustrate the nymph based on specimens from Hidalgo County, Texas. The palpal lobe of G. gonzalezi has 7–8 small teeth in a straight line with the bifid end tooth approximately the same size as the more proximal teeth, typical of the Gomphurus fraternus-group. Gomphurus gonzalezi is distinct from the other species in this group by the long, round-tipped posterolateral spines on abdominal segment 9. In the Lower Rio Grande, the nymphs of G. gonzalezi bury themselves in sand and mud in slow flowing reaches.

Quantifying the degree of bias from using county-scale data in species distribution modeling: Can increasing sample size or using county-averaged environmental data reduce distributional overprediction?

Abstract Citizen‐science databases have been used to develop species distribution models (SDMs), although many taxa may be only georeferenced to county. It is tacitly assumed that SDMs built from county‐scale data should be less precise than those built with more accurate localities, but the extent of the bias is currently unknown. Our aims in this study were to illustrate the effects of using county‐scale data on the spatial extent and accuracy of SDMs relative to true locality data and to compare potential compensatory methods (including increased sample size and using overall county environmental averages rather than point locality environmental data). To do so, we developed SDMs in maxent with PRISM‐derived BIOCLIM parameters for 283 and 230 species of odonates (dragonflies and damselflies) and butterflies, respectively, for five subsets from the OdonataCentral and Butterflies and Moths of North America citizen‐science databases: (1) a true locality dataset, (2) a corresponding sister dataset of county‐centroid coordinates, (3) a dataset where the average environmental conditions within each county were assigned to each record, (4) a 50/50% mix of true localities and county‐centroid coordinates, and (5) a 50/50% mix of true localities and records assigned the average environmental conditions within each county. These mixtures allowed us to quantify the degree of bias from county‐scale data. Models developed with county centroids overpredicted the extent of suitable habitat by 15% on average compared to true locality models, although larger sample sizes (>100 locality records) reduced this disparity. Assigning county‐averaged environmental conditions did not offer consistent improvement, however. Because county‐level data are of limited value for developing SDMs except for species that are widespread and well collected or that inhabit regions where small, climatically uniform counties predominate, three means of encouraging more accurate georeferencing in citizen‐science databases are provided.

Description of the larva of Somatochlora margarita (Odonata: Corduiiidae)

Abstract The larva of Somatochlora margarita is described from a specimen reared from the egg to the final stadium. The larva, previously unknown, is morphologically similar to the larvae of S. calverti, S. filosa, S. ozarkensis, and S. provocans. Combinations of diagnostic characters are given for distinguishing these species. Growth of this species is discussed with respect to other species of Somatochlora and Odonata.