The life cycle of the Siamese shield leech, Placobdelloides siamensis Oka, 1917

by Krittiya Chiangkul, Poramad Trivalairat, Watchariya Purivirojkul

Placobdelloides siamensis is a glossiphoniid leech with a short life cycle. In a laboratory setting, ten mature P. siamensis left their host (a turtle) after feeding for approximately three days and initiated copulation. The adults spent 3–4 days gestating before depositing eggs (272.8±62.9 eggs/clutch; range: 186–359 eggs/clutch). The eggs then changed from a creamy white to a creamy brownish color before hatching. Hatching occurred after incubation on the parent's ventral surface for 5–7 days. The transparent brood, with a single pair of red eyes, spent a couple of weeks under the venters of their parents. After this period, they left their parents and grew to maturity in 10–15 days; leeches were considered mature when their color was similar to that of their parents and they performed their first copulation. In addition, the mature leeches survived for 163 days on one feeding.