Microplana gadesensis Vila-Farré et al., 2008

Jones, Hugh D. & Mcdonald, Jillian C., 2021, A new species of terrestrial planarian of the genus Microplana (Platyhelminthes Turbellaria; Tricladida: Continenticola) from Yorkshire, United Kingdom; with a discussion of Microplana humicola Vejdovsky 1890, Zootaxa 4980 (1), pp. 174-184 : 182-183

Microplana gadesensis Vila-Farré et al., 2008 .

This species, found in south west Spain, is about 1 cm long and has a brown dorsal surface with dark dots. There are 4 to 6 pairs of testes. The sperm ducts open separately into the anterior of the penis bulb. A seminal vesicle is mentioned as part of the ejaculatory duct, but not figured. No mention is made of stored sperm. A genito-intestinal duct and a long conical penis are present, the latter projecting into the female genital atrium (similar to the WF09 specimen). The copulatory apparatus is thus broadly similar to our specimens and from the information available in Vila-Farré et al. (2008) we cannot pinpoint an anatomical character that that is definitively different. However, the colour alone is probably enough to distinguish our specimens from this species.

We are thus not able to identify the specimens with certainty as any previously described species of Microplana . Nor do they resemble any of the species listed under the collective species Statomicroplana . They are consequently described as a new species: Microplana edwardsi Jones & McDonald.

Both specimens are fully mature, each with a well-developed copulatory apparatus and copious mature sperm in the sperm ducts. However, the testes in both are barely discernable and presumed to be spent. The ovaries and ovovitelline ducts, however, are well-developed. This could suggest that this species is protandrous. Vejdovsky (1890) notes that in M. humicola collected in September, the male apparatus was well developed but the female genital organs were not. Schneider (1935) comments that his specimens were protandrous.

Molecular studies of similar specimens might clarify matters as to their identity and their relationship to other species but the same specimens would have to be used for molecular analysis and anatomical description in order to be certain that the same species is being studied, similar to the protocol of Mateos et al. (2017).

The small size means that it is easily overlooked or can be confused for juvenile specimens of other species. For the same reason, its distribution is probably more widespread than the single locality known. We presume that the species is probably native to the British Isles rather than having been introduced, though there is no evidence either way. We can only speculate, again with no evidence, that it possibly feeds on small soil arthropods such as collembolans, but it could also be a scavenger, feeding on almost any dead or wounded animal. One of us (J. McD) attempted to keep specimens alive and offered them a variety of potential food items (earthworms, millipedes, slugs, slug eggs, snails, hatchling flatworms, even a fungus), but the specimens were not observed feeding on any item and dissolved soon after collection. Only chance observations in the field or further observations on captive animals, should they become available, would provide some evidence.