How Did E. M. Walker Measure the Length of the Labium of Nymphs of \u3ci\u3eAeshna\u3c/i\u3e and \u3ci\u3eRhionaeschna\u3c/i\u3e (Odonata: Aeshnidae)?

The exhaustive studies of nymphs of Aeshna Fabricius and Rhionaeschna Förster by E. M. Walker (1912-1958) have long guided the taxonomy of these groups and formed the basis for keys still in use today. However, uncertainty about how he measured the length of the labium, including the varied terminology he used over the duration of his career concerning this structure, has led to confusion about application of his taxonomic recommendations. We recalculated ratios of the maximum width/length [W(max)/L] by measuring the illustration dimensions of folded labia and prementums in publications throughout his career and compared these data with the ratios he stated in those publications and with ratios derived from measurements of specimens in our collections. Our results show that from 1912 to 1941, Walker restricted length measurement to the prementum proper (which he called the “mentum of the labium”), exclusive of the ventrally visible portion of the postmental hinge. However, in 1941 he reported ratios from length measurements done two ways, excluding the postmental hinge in his description of the nymph of A. verticalis Hagen, but including the hinge in his description of the nymph of A. septentrionalis Burmeister (Whitehouse 1941). In Walker’s most recent and influential work (1958), he included the postmental hinge in labium length measurements of nine species, but restricted length measurements to the prementum for five others. He was consistent with the use of terms, using both “folded labium” by which he meant the prementum plus the postmental hinge, and “prementum” by which he meant only that structure. However, Walker’s descriptions of the labium in his latest work are buried in long, frequently punctuated sentences that for most species include the terms “folded labium” and “prementum” in the same sentence, so careful reading is required to know which term is intended in the width/length ratio. Width/length ratios we each calculated independently were invariably similar for a given species and were usually similar to Walker’s stated ratio for that species. These similarities affirm our conclusion that while labium measurements must be done with care, they are closely repeatable among workers and will consistently lead to correct determinations in properly designed couplets of dichotomous keys to these genera. We recommend measuring the length of the prementum proper in future studies of these genera when labium ratios are calculated because we found less variability in those cases than when the measurements included the postmental hinge. An approximate conversion between the two methods of calculating W(max)/L ratios can be made as follows: ratio calculated when the length of the prementum excluding the postmental hinge is used x 0.88 is approximately equal to the ratio when the postmental hinge is included for species of Aeshna and Rhionaeschna in North America

Efficacy of Morphological Characters for Distinguishing Nymphs of \u3ci\u3eEpitheca Cynosura\u3c/i\u3e and \u3ci\u3eEpitheca Spinigera\u3c/i\u3e (Odonata: Corduliidae) in Wisconsin

Attempts to distinguish exuviae and last-instar nymphs of Epitheca cynosura (Say) and Epitheca spinigera (Selys) (Odonata: Corduliidae) using lateral spine characters have proven to be unreliable, and recent use of setae counts on only one side of the prementum or one labial palp have led to confusion because these structures often hold unequal numbers of setae on the two sides of the same specimen. Based on exuviae of 67 reared E. cynosura and 55 reared E. spinigera from lakes throughout Wisconsin, we tested the efficacy of previously used character states for distinguishing these species and searched for new characters to improve the reliability of regional keys. The most reliable diagnostic character was the combined number of setae on both sides of the prementum and on both labial palps (≤ 35 – E. cynosura; ≥ 36 – E. spinigera), which correctly determined 96% of our specimens. For the small percentage of specimens that lie in the region of overlap in total setae number, we found that total exuviae length, cerci ÷ epiproct ratios of females, tubercle distance ÷ epiproct ratios of males, and the shape of the dorsal hook on segment 8 could be used to strengthen determinations

The Puzzling Presence of Lestes australis (Odonata: Lestidae) in Wisconsin - Does This Species Migrate?

Lestes disjunctus australis Walker, 1952 was named as a subspecies of Lestes disjunctus Selys, 1862. In recent decades it has been considered deserving of full species status by most specialists. The core of its eastern North American range is south of Wisconsin, but during April through June of some years, mature individuals, and occasionally reproductive behavior, are observed at shallow ponds and wetlands mostly in the southern half of the state. Since first recorded in Wisconsin in 2002, it has been detected in 13 of Wisconsin’s 72 counties. However, there has been no unequivocal documentation of successful reproduction in the state. Various possibilities regarding long-range dispersal or facultative migration of this species and other species of Zygoptera are discussed

How Did E. M. Walker Measure the Length of the Labium of Nymphs of \u3ci\u3eAeshna\u3c/i\u3e and \u3ci\u3eRhionaeschna\u3c/i\u3e (Odonata: Aeshnidae)?

The exhaustive studies of nymphs of Aeshna Fabricius and Rhionaeschna Förster by E. M. Walker (1912-1958) have long guided the taxonomy of these groups and formed the basis for keys still in use today. However, uncertainty about how he measured the length of the labium, including the varied terminology he used over the duration of his career concerning this structure, has led to confusion about application of his taxonomic recommendations. We recalculated ratios of the maximum width/length [W(max)/L] by measuring the illustration dimensions of folded labia and prementums in publications throughout his career and compared these data with the ratios he stated in those publications and with ratios derived from measurements of specimens in our collections. Our results show that from 1912 to 1941, Walker restricted length measurement to the prementum proper (which he called the “mentum of the labium”), exclusive of the ventrally visible portion of the postmental hinge. However, in 1941 he reported ratios from length measurements done two ways, excluding the postmental hinge in his description of the nymph of A. verticalis Hagen, but including the hinge in his description of the nymph of A. septentrionalis Burmeister (Whitehouse 1941). In Walker’s most recent and influential work (1958), he included the postmental hinge in labium length measurements of nine species, but restricted length measurements to the prementum for five others. He was consistent with the use of terms, using both “folded labium” by which he meant the prementum plus the postmental hinge, and “prementum” by which he meant only that structure. However, Walker’s descriptions of the labium in his latest work are buried in long, frequently punctuated sentences that for most species include the terms “folded labium” and “prementum” in the same sentence, so careful reading is required to know which term is intended in the width/length ratio. Width/length ratios we each calculated independently were invariably similar for a given species and were usually similar to Walker’s stated ratio for that species. These similarities affirm our conclusion that while labium measurements must be done with care, they are closely repeatable among workers and will consistently lead to correct determinations in properly designed couplets of dichotomous keys to these genera. We recommend measuring the length of the prementum proper in future studies of these genera when labium ratios are calculated because we found less variability in those cases than when the measurements included the postmental hinge. An approximate conversion between the two methods of calculating W(max)/L ratios can be made as follows: ratio calculated when the length of the prementum excluding the postmental hinge is used x 0.88 is approximately equal to the ratio when the postmental hinge is included for species of Aeshna and Rhionaeschna in North America

Efficacy of Morphological Characters for Distinguishing Nymphs of \u3ci\u3eEpitheca Cynosura\u3c/i\u3e and \u3ci\u3eEpitheca Spinigera\u3c/i\u3e (Odonata: Corduliidae) in Wisconsin

Attempts to distinguish exuviae and last-instar nymphs of Epitheca cynosura (Say) and Epitheca spinigera (Selys) (Odonata: Corduliidae) using lateral spine characters have proven to be unreliable, and recent use of setae counts on only one side of the prementum or one labial palp have led to confusion because these structures often hold unequal numbers of setae on the two sides of the same specimen. Based on exuviae of 67 reared E. cynosura and 55 reared E. spinigera from lakes throughout Wisconsin, we tested the efficacy of previously used character states for distinguishing these species and searched for new characters to improve the reliability of regional keys. The most reliable diagnostic character was the combined number of setae on both sides of the prementum and on both labial palps (≤ 35 – E. cynosura; ≥ 36 – E. spinigera), which correctly determined 96% of our specimens. For the small percentage of specimens that lie in the region of overlap in total setae number, we found that total exuviae length, cerci ÷ epiproct ratios of females, tubercle distance ÷ epiproct ratios of males, and the shape of the dorsal hook on segment 8 could be used to strengthen determinations

Cordulegaster talaria, n. sp. (Odonata: Cordulegastridae) from west-central Arkansas

Volume: 106Start Page: 830End Page: 83

Description of the larva of Gomphus sandrius tennessen (Odonata: Gomphidae)

Volume: 108Start Page: 381End Page: 38

Psaironeura angeloi Tennessen, 2016, sp. nov.

Psaironeura angeloi sp. nov. (Figures 1–15) Material examined. — Holotype ♂: ECUADOR: Esmeraldas Province, small stream 5.6 km NW of Lita, 00.893°N 78.510 °W, 4 -II- 1997, KJT leg. Allotype ♀: same data as holotype. Paratypes (total 17 ♂, 1 ♀): ECUADOR, same data as holotype, 8 ♂, 1 ♀, KJT leg; Esmeraldas Province, pool in stream 36.5 km NW of Lita, 01.106°N 78.707 °W, 3 -II-1997, 2 ♂, KJT leg; Esmeraldas Province, small stream 2.0 km N of Lita, 00.878°N 78.458 °W, 5 - II-1997, 2 ♂, KJT; Manabí Province, small forest stream 0.5 km N of Chindul, Hwy. E 15, 00.239°N 79.874 °W, 1 - III-2010, 3 ♂, KJT leg, 2 ♂, J. J. Daigle leg. All specimens acetoned; holotype, allotype and 13 paratypes (13 ♂ and 1 ♀) deposited in FSCA, Gainesville, Florida, USA; 1 ♂ deposited in DRP Collection and 2 ♂ in JJD Collection. Additional FSCA specimens studied, all previously determined as P. remissa (20 ♂, 6 ♀).— COSTA RICA: Alajuela Province, Oricuajo, nr. Río Jesús María, 9.95 °N 84.617 °W, VII-1911, 1 ♂, J. F. Tristan leg; Cartago Province, Reventazon Valley below Juan Vinas, 28 -VI-1909, 1 ♂, 28 -VII-1909, 1 ♀, P. P. Calvert leg; Heredia Province, Finca La Selva, 1.5 mi. S Puerto Viejo, 19 -IX-1966, 1 ♂, D. R. & M. L. Paulson leg; Finca La Selva, 1.5 mi. S Puerto Viejo, 9 -IV- 67. 3 ♂ 1 ♀, D. R. & M. L. Paulson; same locality, 13 -VIII-1967, 1 ♂ 1 ♀, D. R. & M. L. Paulson leg; Puerto Viejo, La Selva Biological Station, 25 -VI-1988, 3 ♂, C. Esquivel leg; same locality, 19 -VII-1988, 1 ♂, C. Esquivel leg. NICARAGUA: Rio San Juan, Refugio Bartola, forest streams, Rio San Juan and Rio Bartola, 10.967 °N 84.333 °W, 6 -VIII-2002, 1 ♂ 1 ♀, T. & A. Donnelly leg; same locality, 8 -VIII-2002, 4 ♂, J. J. Daigle leg; same locality, 8 -VIII-2002, 2 ♂ 1 ♀, W. F. Mauffray leg. PANAMA: Canal Zone, Pipeline Road, 31 -III-1970, 1 ♂, E. S. Morton leg; Pipeline Road, 1.7-4.8 km NW of Gamboa, 5 -II-1971, 2 ♂, E. S. Morton & T. W. Donnelly leg; Barro Colorado Island, 18 -V-1960, 1 ♂ 1 ♀, R. B. Cumming leg.Published as part of Tennessen, Kenneth J., 2016, Psaironeura angeloi, a new species of damselfly (Zygoptera: Coenagrionidae) from Central and South America in Zootaxa 4078 (1), DOI: 10.11646/zootaxa.4078.1.5, http://zenodo.org/record/26697

FIGURES 2 – 11. Heteropodagrion sanguinipes. 2 in The madicolous nymph of Heteropodagrion sanguinipes Selys (Odonata: Megapodagrionidae)

FIGURES 2 – 11. Heteropodagrion sanguinipes. 2) Right antenna; 3) Prementum, dorsal view; 4 a) ridges of prementum, dorsal view; 4 b) ridges of prementum at 45 ° angle; 5) Ligula; 6) Right palpal lobe; 7 a) Right mandible, ental view; 7 b) Left mandible, ental view; 8) Left hind femur; 9) Male cercus (c), lateral view (p = base of paraproct); 10) S 8 – 10, female, lateral view; 11) Left lateral gill, lateral view