Paraleptophlebia praepedita (Eaton, 1884: 99)

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 : 20

Paraleptophlebia praepedita (Eaton, 1884: 99)

Leptophlebia praepedita Eaton, 1884 (original description)

Description of Nymph: Needham 1905: 49; Gordon 1933: 123

Nymphs of P. praepedita can be recognized from other members of the northeast Paraleptophlebia that have posterolateral projections of abdominal segments VIII and IX ( Fig. 3b ) by the deeply forked abdominal gills lacking long, hair-like marginal setae ( Fig. 22a ), legs uniform light brown without bands (as in Figs. 23a,b ), ventral edge of femora with about five short hair-like setae, lateral margins of abdominal sternites with distinct longitudinal brown bands ( Figs. 35a,b ), first segment of maxillary palp long, with apex reaching beyond outer corner of galea-lacinia and with only few setae on ventral surface (as in Figs. 27a,b ), posterolateral projections on segments VIII and IX with IX distinctly larger than VIII ( Fig. 3b ), color pattern of abdominal tergites brown with pattern composed of one large pale median spot flanked by two smaller pale spots, especially consistent on tergites VII–X ( Figs. 36a–d ) with pale lateral margins, and abdominal gills with the clear membranous portion broad on basal half of gill filaments and greatly reduced over apical half of gill filaments ( Figs. 2 , 38 ). Most characters seem consistent on nymphs from mid-development to the final instar. Abdominal gills may appear to lack marginal setae, but usually have a few short, widely spaced marginal setae ( Figs. 2 , 35 ), small setae often require back-illumination to observe. The background color of legs is uniform light to medium brown but can be yellow brown on some specimens, pale areas occur near apices of femora (as in Figs. 23a,b ) and are most distinctive on live or freshly preserved specimens. On some specimens a faint pale oval area may also occur in the middle of the dorsal surface of femora. The rounded apical corner of femora is slightly darker brown compared to the rest of the surface (as in Fig. 23b ). The basal area of tibiae near joint with femora can also appear slightly darker brown than the rest of the surface, but does not appear as a distinct band. The ventral edge of the femora has three to five short, hair-like setae that are dispersed along the edge, with most occurring close to the base of the edge as well as a row of about 22 biserrate spine-like setae. Lateral margins of abdominal sternites with distinct brown lateral longitudinal bands ( Figs. 35a,b ). Brown lateral longitudinal bands usually have uniform width over the length of the abdomen, but can be slightly wider along the inner edges ( Fig. 35a ). Bands are relatively consistent between male and female nymphs, but can fade after long term preservation in ethanol ( Fig. 35b ). Segment 1 of the maxillary palp is long with its tip above the outer corner of the galea-lacinia, but only reaching about halfway to the mid-point of the longest crown setae (as in Fig. 27a ). The ventral surface of segment 1 has only a few scattered hair-like setae and one or two small spine-like setae (as in Fig. 27b ). The color pattern of abdominal tergites is distinctive and similar between male and female nymphs, especially regarding the pale spots on tergites VII–X ( Figs. 36 a–d ). This pattern usually consists of a large pale median spot flanked by two smaller pale spots. The pattern of pale spots can be variable on tergites I–VI between male ( Figs. 36a,b ) and female ( Figs. 36 c,d ) nymphs. On tergites I–VI the arrangement of three pale spots can be maintained as occurs on tergites VII with large distinct spots ( Figs. 36a,c ) or reduced with only smaller spots evident ( Fig. 36d ) or interrupted with perhaps one or two tergites (i.e., V and/or VI) lacking medial pale spots, but with pale spots present on other tergites ( Fig. 36b ). On tergite IX pale lateral spots merge with medial spot forming a distinctive pale inverted T-shape. All tergites have pale margins and usually a small brown mark at the posterolateral corners and over each gill insertion. Abdominal gills deeply forked and with the clear membranous portion broad on basal half to two-thirds of gill filaments with a distinct transition to a much-reduced clear membrane covering the apical portion of gill filaments ( Figs. 2 , 38 ). The pronotum has two large pale spots laterally that are distinctive on live or recently preserved specimens ( Fig. 37a ), but can fade after long term preservation ( Fig. 37b,c ). In addition, groups of several large spine-like setae occur on the anterior corners of the pronotum. This character may be useful in separating early instar nymphs from those of P. moerens , which seem to have only two to three short spine-like setae on the anterior corners of the pronotum.

Paraleptophlebia praepedita is an uncommon (potentially rare) species in the northeast Nearctic region with records in only 5 of the 14 states and provinces ( Table 2). Paraleptophlebia praepedita , like P. ontario , has a somewhat anomalous regional distribution with records in eastern MA, central and northern NY, southeastern PA ( Hoover 1993), southern QC, and western NS. The continental range of P. praepedita was summarized by Garlick et al. (2012) and shows most records occurring in midwestern states that border either the Ohio or Mississippi Rivers. The northernmost record is from Churchill, Manitoba ( Harper & Harper 1981; Zhou et al. 2010) indicating that P. praepedita can survive the extreme conditions of higher latitudes and was vagile enough to disperse far from what seems to be the core of its range in the Ohio Valley. Currently there is no obvious reason for the absence of records from the states of ME, NH, VT, and the province of NB, which lie between the records in northern NY, southern QC, and western NS. Similarly, there is no obvious reason for the absence of records from CT and RI that lie in close proximity to known P. praepedita sites in eastern MA. Little has been published on the aquatic habitat of P. praepedita nymphs ( Needham 1905, Gordon 1933, and Wiggins et al. 1980), but from these accounts it seems nymphs occur along the margins of pools or transitional runs of small, low gradient streams that have some rooted aquatic vegetation and benthic substrates composed mostly of small mineral particles. Currently among the species treated here, only P. praepedita nymphs have been observed to occur in temporary vernal pools ( Wiggins et al. 1980). The ability to use temporary vernal pools as possible stepping-stone habitats would seem to enhance the dispersal ability of P. praepedita , which makes the current gaps in the northern part of its range even more puzzling. Paraleptophlebia praepedita is likely secure in its distribution across the majority of its midwestern range, however, its future in the northeastern region is uncertain. Before any assessment can be made concerning the vulnerability of P. praepedita to the effects of climate change in the northeastern part of its range it first must be established that it is still present because all published records are more than 80 years old (only the unpublished record from PA (1994) can be considered recent). The oldest records of P. praepedita are from an area of eastern MA (Eaton 1884) that is now a highly settled suburb of Boston. Suitable stream habitats still occur in this area, and it is possible that P. praepedita is still present, but somehow overlooked by MA environmental and wildlife agencies that routinely monitor streams because it inhabits parts of streams that are not included in standard sampling protocols. Across the midwestern range of P. praepedita suitable habitats are abundant and this combined with its broad distribution suggests that it is likely secure in this part of its range with regards to predicted changes in aquatic habitat resulting from effects of climate change. In the northeast region habitats like those of the midwest are also common, however, P. praepedita is uncommon to rare. This suggests that the northeastern distribution of P. praepedita is not the result of an association with a unique habitat type. For whatever reason, the lack of recent records of P. praepedita in the northeastern Nearctic region prevents any assessment of vulnerability related to the effects of climate change on aquatic habitats. If further study determines that the lack of records reflecting a high level of regional rarity is real, and not the result of sampling effort, it could mean that P. praepedita is particularly vulnerable to the predicted effects of climate change in this part of its range.

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. 22–24: gills and legs of Paraleptophlebia nymphs. 22a. dorsal view of lateral gills of P. moerens with gill margins lacking long, hair-like setae, 22b. lateral view of gills of P. debilis with gill margins lacking long, hair-like setae, 23a dorsal view of legs of live P. moerens nymph showing typical brown color pattern without distinct bands, 23b. close-up of foreleg of preserved P. moerens nymph showing uniform brown color, pale areas visible on live nymphs are much less distinct after being preserved, 24a. lateral view of legs of P. debilis showing distinct bands on all leg segments, 24b. lateral view of legs of P. ontario showing partial brown band near apex of femora and dark brown mark on tibiae at joint with femora; dark brown on femora is often diffuse and usually does not encircle the segment.

FIGS. 35a–b: nymphs of Paraleptophlebia praepedita. 35a. ventral view of the abdomen of a female nymph with arrow indicating well-formed and symmetrical dark lateral bands on sternites, 35b. ventral view of the abdomen of a male nymph with similar well-formed lateral bands on sternites, brown color also extends on to the sides of the styliger plate.

FIGS. 27a–c: maxillae of Paraleptophlebia nymphs. 27a. right maxilla of P. ontario (dorsal view), 27b. close-up of segment 1 of maxillary palp (ventral surface) of P. ontario, 27c. right maxilla of P. debilis (dorsal view), 27d. close-up of segment 1 of maxillary palp (ventral surface) of P. debilis.

FIGS. 36a–d: nymphs of Paraleptophlebia praepedita. 36a. dorsal view of abdominal color pattern of male nymph with median pale spots extending from tergite I–X, 36b. dorsal view of abdominal color pattern of male nymph with median pale spots absent on tergites V–VI, but present on tergites I–IV and VII–X, 36c. dorsal view of abdominal color pattern of female nymph with median pale spots extending from tergite I–X, 36d. dorsal view of abdominal color pattern of female nymph with median pale spots much reduced on tergites I–III, but present on tergites VI–X.

FIGS. 38–39: nymphs of Paraleptophlebia. 38. lateral view of the abdomen gills of P. praepedita with arrow indicating distinct transition point of the clear membranous portion of gill filaments past which the clear membrane surrounding the medial trachea is much reduced, 39a. ventral view of the abdomens of female nymphs of P. moerens, arrow indicates dark lateral shading on sternites VIII and IX, 39b. ventral view of the abdomens of male nymphs of P. moerens, arrow indicates depressions along edges of sternites and dark lateral shading on sternites VIII and IX.

FIGS. 37a–c: nymphs of Paraleptophlebia praepedita. 37a. female nymph after short term preservation in ethanol showing large white spots on sides of the pronotum, 36b. female nymph after long term preservation in ethanol showing medial pair of large white spots on the pronotum reduced, but lateral spots still distinct, 36c. male nymph after long term preservation in ethanol showing same pattern of pale spots on the pronotum as indicated for female.