Unique mating behavior, and reproductive biology of a simultaneous hermaphroditic marine flatworm (Platyhelminthes, Tricladida, Maricola)

Abstract

Flatworms generally are simultaneous hermaphrodites that exhibit various kinds of mating behavior. Here we report on the mating behavior and reproductive biology of the planarian Paucumara falcata. We recognized three phases in its mating behavior: a courtship, copulation, and postcopulatory phase. During the last‐mentioned phase, the partners showed a unique and very characteristic behavior in which their bodies intertwined, forming a spiral. Histological study of partners in copula revealed that the sclerotic tip of the musculo‐parenchymatic organ pierces the body wall of the partner and then becomes lodged in its parenchyma, suggesting that this organ may act as an anchor, thus stabilizing the worms during copulation. Similar organs in other species of marine triclad may also perform a stabilizing role during copulation. During copulation in individuals of P. falcata, sperm transfer was reciprocal or only unilateral. Copulation duration ranged 13–35 min (average 20 ± 5 min), irrespective of whether the mating was successful (i.e., resulted in the production of fertile cocoons). The spiraling phase lasted on average 10 min; some worms did not show the postcopulatory spiraling phase during their mating behavior. After successful copulation, an individual worm produced 1–12 fertile cocoons over a period of 1–17 days; from a cocoon hatched either one young (in 70% of the cases), or two young worms.

A new species of Dugesia (Platyhelminthes, Tricladida, Dugesiidae) from China, with an account on the histochemical structure of its major nervous system

“…Histological sections were made at intervals of 6 μm. Preparations were stained with both modified Cason's Mallory-Heidenhain stain and haematoxylin (see Yang et al 2020…”

Three new species of Macrostomum (Platyhelminthes, Macrostomorpha) from China and Australia, with notes on taxonomy and phylogenetics

“…The dehydrated specimens were embedded in paraffin and serially sectioned along the sagittal plane (thickness 6 μm) using a manual rotary microtome (Leica RM2235, Leica Biosystems, Germany). After being stained with either hematoxylin-eosin (H&E) or modified Cason’s Mallory–Heidenhain stain and hematoxylin ( Yang et al 2020 ), the specimens were mounted in neutral balsam for histological observation. Lactic acid phenol liquid (lactic acid: phenol = 1:1 in volume) was used for penis stylet dissection.…”

Molecular phylogeny and ethology of the Family Plagiostomidae (Platyhelminthes, Prolecithophora), with integrative description of a new species, Plagiostomum robusta A. Wang, sp. nov.

“…The continuous tissue sections were prepared referring to the method of Yang et al (2020). The flatworms were starved for three days and placed on glass slides.…”