Paraleptophlebia guttata ( McDunnough, 1924: 95 )

Burian, Steven K., 2024, Nymphs of the Northeastern Nearctic Species of Neoleptophlebia Kluge, 1997 and Paraleptophlebia Lestage, 1917 (Ephemeroptera: Leptophlebiidae), Zootaxa 5521 (1), pp. 1-65 : 12-13

Paraleptophlebia guttata ( McDunnough, 1924: 95)

Leptophlebia guttata McDunnough, 1924 (original description)

Description of Nymph: Ide 1930: 210; Gordon 1933: 123

Nymphs of P. guttata can be recognized from other members of the northeast Paraleptophlebia that only have posterolateral projections of abdominal segment IX ( Figs. 4b ) by the extremely long maxillary palps ( Figs. 9a,b ), tarsal claws without denticles ( Fig. 12 ); posterolateral corners of abdominal tergites II–VI with a small dark spot at gill insertions ( Figs. 10a–d ), and apex of femora with group of 3–4 large, blunt spine-like setae ( Fig. 11 ). Structural characters seem consistent on nymphs from mid-development to the final instar. Color pattern characters of abdominal tergites vary between male to female nymphs, being most distinctive on male nymphs. The extremely long maxillary palps are clearly visible extending forward beyond the anterior edge of the head ( Figs. 10a,b ), even on early instar nymphs. The first segment of the maxillary palp is longer than on any other species treated in this study and reaches to or beyond the tips of the longest crown setae of the galea-lacinia of maxillae ( Figs. 9a,b ). In addition, maxillary palp segments 2 and 3 are also long, slender and have a relatively consistent width over their respective lengths ( Fig. 9a ). Claws of all legs lack denticles ( Fig. 12 ), but because claws are small, high magnification (i.e., 400x) is required to directly observe this character. The color pattern character of abdominal tergites has appeared in several of the previous keys ( Burks 1953, McCafferty et al. 2017, and Traver 1935) as an important key character. However, the interpretation of this character has been problematic for several reasons: (1) text descriptions vary as to what actually constitutes the small dark spot mentioned in those keys and its position relative to the corners of tergites, (2) this character has never been illustrated, (3) color patterns of abdominal tergites of P. guttata nymphs vary between males and females, but there is no mention of this in keys, and (4) P. guttata nymphs have a variable-width dark edge on the posterior margins of tergites II–VI that is not mentioned in any key, but on some specimens can be similar to the condition described in keys for nymphs of P. strigula , which have only short dark streaks on the posterior margins of tergites. Abdominal tergites of male and female P. guttata nymphs do have a dark spot that occurs in the posterolateral corner of tergites II–VI above the gill insertions ( Figs. 10a–d ), but these spots are variable. The spot can vary in size and shape from a relatively distinct dark compact dot that is clearly separated from the coloration of the posterior margin and the area of the gill insertion to a larger and more diffuse dark blotch that is much less sharply defined and can appear to merge with dark shading at the gill insertion. Further, background color of tergites II–VI plays an important role in correctly observing this diagnostic dark spot ( Figs. 10a,c ). Tergites II–VI can vary on male nymphs from light to medium brown. On lightly pigmented abdomens the dark lateral spots are clear, but on the darker abdomens these dark marks are much less distinctive. Observing these marks on female nymphs is even more problematic because they all have medium to dark brown abdominal tergites ( Figs. 10b,c ). Although this color character is useful, it is often difficult to interpret across the full range of variation that exists in populations. It is used here as a character in support of the more decisive characters of the maxillary palp and tarsal claws. Finally, the group of large and blunt setae near the apex of femora is presented as another useful ancillary character. However, one potential problem with this character is that the large setae seem to be susceptible to damage. On several specimens studied one or more setae were broken, thus making it difficult to tell whether they were long and blunt, hence relegating this character to a supporting role as a key character.

Nymphs of P. guttata are widely distributed and common throughout the northeast Nearctic region with records in 11 of the 14 states and provinces ( Table 2). Only RI, NL-I, and PE lack records. The absence of records for RI is likely the result of sampling effort, but the lack of records from major islands (NL-I and PE) may reflect actual absences because of the difficulty of dispersal across straits to offshore islands. The widespread distribution of P. guttata is indicative of its wide habitat tolerances being able to inhabit suitable microhabitats in both small first and second order streams and third order rivers ( Burian & Gibbs 1991). In mid-summer, nymphs of P. guttata are particularly abundant in shallow riffles of second and third order stream channels where loose CPOM becomes trapped among cobble and gravel.The widespread distribution of P. guttata is indicative of its wide habitat tolerances, which allow it to occupy suitable microhabitats in a wide range of streams and rivers ( Burian & Gibbs 1991). Thus, like N. adoptiva and N. mollis , P. guttata is likely secure across its northeastern range with regards to predicted changes in regional hydrology because of climate change ( Hicke et al. 2022).

abbreviations are US States and Canadian Provinces (for province of Newfoundland & Labrador NL-I = island area and NL-Lab = mainland Labrador). Values given under S Regions heading is the sum of all occurrences across states and provinces. Column totals are species richness per state or province.

**—Records for PE, not reviewed here, were discovered after this study was completed and listed Paraleptophlebia sp. in: Eedy, R.I., & D.J. Giberson (2007) Macroinvertebrate distribution in a reach of a north temperate eastern Canadian river: Relative importance of detritus, substrate and flow. Fundamental and Applied Limnology (Archiv für Hydrobiologie) 169: 101-114.

Figures

FIGS. 1–4: gills and abdominal tergites VIII–X of Neoleptophlebia and Paraleptophlebia nymphs. 1. N. adoptiva gill 4, 2. P. praepedita gill 4, 3a. N. assimilis tergites VIII–X, 3b P. praepedita tergites VIII–X, 3c. P. volitans tergites VIII–X, 3d. P. moerens tergites VIII–X, 4a. N. adoptiva tergites VIII–X, 4b. P. guttata tergites VIII–X.

FIGS. 9–12: mouth- and bodyparts of Paraleptophlebia guttata nymphs. 9a. right maxilla (dorsal view), 9b. close-up of dorsal surface of segment 1 of maxillary palp, 10a. dorsal view of view of abdomen of male nymph, 10b. dorsal view of abdomen of female nymph, 10c. lateral view of abdominal tergites of male nymph, 10d. lateral view of abdominal tergites of female nymph, 11. foreleg of male nymph, white circle indicates location of large apical spine-like setae on femur, 12. close-up of foreclaw, arrow indicates inner edge lacking denticles.