Species of Macrostomum (Macrostomorpha: Macrostomidae) from the coastal region of Lima, Peru, with comments on M. rostratum Papi, 1951

Abstract

Species of Macrostomum are present in almost all regions of the world. These flatworms occur in different kinds of environments, from freshwater to marine ecosystems. Although Peru is considered one of the megadiverse countries in South America, little is known about freshwater microturbellarians in this country. Here we report the presence of M. rostratum Papi, 1951 for the first time in Peru, in a coastal brackish water wetland, and that of M. quiritium Beklemischev, 1951 and M. tuba Graff, 1882 in an inland portion of a river near the city of Lima. All the species were studied alive. Comments on the habitat and associated fauna are given. Detailed information on the copulatory system is provided for M. rostratum; the male system has a bilobed seminal vesicle with thick walls and full of spindle-shaped sperm cells, and a stylet in the form of a solid curved inverted cone with a subterminal opening located on the concave side of the stylet. These findings led us to suggest that M. rostratum may exhibit a hypodermic mating syndrome. The three species of Macrostomum reported here are widespread and, although the diagnostic characters of the species are present, some morphological differences in the copulatory stylet suggest they are cryptic species.

Checklist of free-living microturbellarian flatworms (Turbellaria, Platyhelminthes) in the Suquía River Basin, Córdoba, Argentina

“…Identification. The morphology and genital system agree with previous observations by Adami et al (2017) and Reyes et al (2017). Living mature individuals about 1,600 µm long, with maximum width of 400 µm (Fig.…”

“…Macrostomum quiritium have been cited for Russia, Poland, and Switzerland (Schärer et al 2011) and was recently reported in the Neotropical region (Adami et al 2017). In contrast to the specimens described here, the Peruvian M. quiritium reported by Reyes et al (2017) are slender.…”

“…Mesostoma ehrenbergii has also been recorded in Australia (Noreña et al 2016). Macrostomum quiritium was reported in the Northern Hemisphere were it has been found in artificial ponds with aquatic vegetation from the tropics (Schärer et al 2011); it only occurs in natural environments in the Neotropical region (Adami et al 2017;Reyes and Brusa 2017).…”

“…Córdoba Province is in the Neotropical region, where many studies have reported on the high species diversity of turbellarians in a variety of aquatic environments (e.g., Marcus 1945aMarcus , 1945bMarcus , 1946Marcus , 1948Marcus , 1950Marcus , 1952Noreña et al 2005;Martínez-Aquino et al 2014;Braccini et al 2016;Reyes and Brusa 2017).…”

A taxonomic review and revisions of Microstomidae (Platyhelminthes: Macrostomorpha)

“…recognition of M. hanatum, still listing M. giganteum as synonymous to M. lineare). Taken together, it is unsurprising that while there has been some recent studies of species diversity within Macrostomorpha in general (e.g., Schockaert 2014;Sun et al 2014;Janssen et al 2015;Fang et al 2016;Reyes & Brusa 2017;Lin et al 2017a, b;), taxonomic research within Microstomidae from even the last 50 years has been restricted to a very few articles (Faubel 1974(Faubel , 1984Rogozin 2015;Atherton & Jondelius 2018 a,b).…”