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