A Candidate Third Transiting Planet on an 18.9-day Orbit around the M Dwarf TOI-4342, Matching a Dynamical Prediction

I present an independent detection and detailed vetting of a candidate third transiting planet around TOI-4342 (TIC 354944123), an M0 dwarf hosting two sub-Neptunes at 5.54 and 10.69 days; the signal was first posted publicly by Eumemic (2026). Nine sectors of TESS 2-minute photometry show a 1182±107 ppm, 2.4 hr transit every 18.908226 days, Rp=2.25±0.13 R⊕, in all ten observed windows (signal-to-noise ratio 11.7). Period, radius and inclination match the planet predicted by E. V. Turtelboom et al. (2025). Difference images place the source within 11″ of the target and exclude every Gaia neighbor able to mimic it. With a speckle contrast curve and the pixel-excluded neighbors removed, TRICERATOPS gives a false-positive probability of 0.018, just above the 0.015 validation threshold, and a nearby-false-positive probability of zero. The three planets are coplanar to within 1° and dynamically stable.