PERLODIDAE NEMOURIDAE

Herhold, Hollister W, Davis, Steven R, Degrey, Samuel P & Grimaldi, David A, 2023, COMPARATIVE ANATOMY OF THE INSECT TRACHEAL SYSTEM PART 1: INTRODUCTION, APTERYGOTES, PALEOPTERA, POLYNEOPTERA, Bulletin of the American Museum of Natural History 459 (1), pp. 1-184 : 1-184

FAMILY PERLODIDAE

“Stripetails” or “Springflies”

Figures 51 (lateral), 52 (dorsal), 53 (ventral)

Plates 29 (lateral), 30 (dorsal), 31 (ventral)

The scanned perlodid is a gravid female specimen, with numerous eggs visible (see section on abdomen). These have been omitted from visualizations for clarity; visceral tracheae anastomose among eggs. Large central air sac begins in mesothorax and extends as far as A3-S in abdomen (also omitted from visualizations for clarity, see fig. 50 ). As mentioned above, adult perlodids have reduced mouthparts and generally do not feed; the head tracheal system is described in full here.

DESCRIPTION: HEAD: H-DCT and H-VCT elongate and winding through prothorax, bifurcating from T2-CT well posteriad of cervix. H-DCT begins straight on entry to head capsule with short H-DVT-DVi before turning medially toward eye, with three branches: H-Oc, H-FtAnt, and H-Ft. H-Oc short, extending laterally into eye. H-Ft-Ant dorsoventral, linking H-DCT with H-Ant from H-VCT. H-DCT blind ending at H-Ft. H-DCC absent. H-VCT generally straight and running anteriad, with anterodorsal H-VCT-DVI and ventral H-Lbm before continuing anteriad to split into H-Ant, H-VC, and H-Md-Lbr. H-Ant lateral, with connection to H-DCT via H-Ft-Ant. H-VC running directly mediad, linking with opposite side of head. H-Md-Lbr continues anteriad, arcing medially with branch into H-Md before continuing anteriorly and blind ending at H-Lbr.

THORAX: T2-S with four tracheae: T2-CT, T2-DB, T2-VB, T2-AWL. T2-CT large in diameter, proceeding anteriorly in sinusoidal curve, much shorter than in Nemouridae , dividing into H-DCT and H-VCT in mid-prothorax. Single T1-Vi present. T1-L running ventrad from H-VCT, with tibial trachea greatly thickened relative to femoral trachea. T1-VC present, extending mediad from each T1-L to connect with opposite side; T1-VC-Avi extending anteriad toward head, looping posteriad near cervix; T1-VC-Pvi running directly posteriad. T2-DB running directly mediad, arcing posteriorly to continue as T2-DLT, with several T2-DLT-Dvi branching dorsally, likely into flight muscle; T2-FM off T2-DLT and T2-DC not visible but likely present. T2-VB posteriad and ventrad, ending blind near mesocoxae; T2-VC present, positioned approximately halfway between forecoxae and mesocoxae; continuation of T2-VB as T2-VLT toward T3-S (as in Nemouridae ) likely present but not visible in this scan. T2-VB-Vi not visible but likely present. T2-AWL begins dorsally, turning posteriorly and ventrad toward midleg, joining T2-PL ventrally from T3-S; T2-AWL with a sharp turn posteriad, likely where T2-AL and T2-Awba (or T2-W-c-r) would split but not visible in this scan; T2-AL tracheal lumen not visible and likely fluid filled in right side; left side of same specimen with gap and smaller trachea connecting. T2-W-c-r not visible but likely present. T3-S with four connections: T3-DB, T3-VB, T2-PWL, T3-AWL. T3-DB short and running directly inward, linking with T2-DLT running anteriad and T3-DLT posteriad; large T3-FM dorsad where T3-DB joins T2-DLT and T3-DLT. T3-FM running dorsad with several tracheae extending into flight muscles; T3-FM continues dorsad, arcing medially to join with opposite side via T3-DC, not visible but likely present. T3-VB running ventrad and posteriad, with numerous branches extending into flight muscule; T3-VB with T3-VC branching inward, meeting opposite side, near ventral sternite. T3-VLT not visible but likely present. T2-PWL running directly anteriad, bifurcating into T2-Pwba extending dorsally and anteriad and T2-PL, mediad. T2-PWBa continues dorsally, with several branches into flight muscle and single, small T2-W-cu-a extending into trailing edge of forewing. T2-PL arcing medially and ventral before turning laterally, joining with T2-AL anteriorly and extending posteriorly into T2-L. T2-L with tibial trachea greatly thickened relative to femoral trachea. T3-AWL running ventrad, just medial from T3-S, with small T3-W-c-r branching dorsally where remaining trachea turns posteriad as T3-AL. T3-W-c-r not visible but likely present.

ABDOMEN: Numerous eggs present, see figure 54 . T 3 -Pwba branching directly from A1-S. A n -VB, A n -SB, A[1..7]-VC absent (or not visible), A8-VC present. A[1..8]-DLT-Dvi present, possibly supplying dorsal vessel. Several segments with elongate visceral tracheae, spanning several segments, including: A2-DLT-Vvi2, extending posteriorly past A5-S; A7-DLT-Vvi, extending anteriorly past A5-S; A6-DLT-Dvi, extending dorsad and anteriorly past A4-S on left side only. Remaining visceral tracheae elongate but winding, often extending past segment boundary before reversing direction, occasionally several times; visceral tracheae often with asymmetric left/right branching patterns. Noticeable lack of left-right commissures with exception of A8-S and right side A8-DLT-Dvi extending mediad, crossing center line and proceeding anteriorly on left side toward A7-S; A8-DLT-Dvi on left side extending anteriorly, not crossing to opposite side. FAMILY NEMOURIDAE

Figures

FIGURE 3. Illustration of the tracheal system of Lepisma saccharina by Šulc (1927). Note dorsal side on left half and venter on right.

FIGURE 50. Alimentary canal air space position in Plecoptera: Perlodidae (top), Nemouridae (bottom).

FIGURE 51. Perlodidae (Plecoptera) lateral.

FIGURE 52. Perlodidae (Plecoptera) dorsal.

FIGURE 53. Perlodidae (Plecoptera) ventral.

FIGURE 54. Perlodidae lateral cross section of abdomen, showing eggs.