Sexual dimorphism, population dynamics and some aspects of life history of Echiniscus mauccii (Tardigrada; Heterotardigrada)

Abstract

A fifteen month study (December 2002 though February 2004

Two new species of Tardigrada from moss cushions (Grimmia sp.) in a xerothermic habitat in northeast Tennessee (USA, North America), with the first identification of males in the genus Viridiscus

“…Miller, Claxton & Heatwole (1999) hypothesized a Gondwana origin of bisexual Echiniscus species, comprising those of the ''arctomys group.'' Although Mitchell & Romano III (2007) reported the first males in the former Echiniscus mauccii [now Claxtonia mauccii (Ramazzotti, 1956)] in North America, our finding of males in Vir. miraviridis sp.…”

“…Only 37 years ago, males were considered completely absent in the widespread genus Echiniscus, at that time composed of about 112 species (Ramazzotti & Maucci, 1983), including the former viridis group (now the genus Viridiscus) within the ''arctomys group''. The first report of males in Echiniscus species was published by Dastych (1987) and later by others (e.g., Claxton, 1996;Miller, Claxton & Heatwole, 1999;Mitchell & Romano III, 2007;Claxton & Dastych, 2017, who reported males in several species of Echiniscus. Miller, Claxton & Heatwole (1999) hypothesized a Gondwana origin of bisexual Echiniscus species, comprising those of the ''arctomys group.''…”

Genetic diversity in the parthenogenetic reproducing tardigrade Echiniscus testudo (Heterotardigrada: Echiniscoidea)

“…The genus was once thought to be entirely parthenogenetic (Kristensen, 1987), but later studies have found males to be common in some non-European species (Dastych and Kristensen, 1995;Miller et al, 1999). Mitchell and Romano (2007) and Guil and Giribet (2009) reported the relatively low occurrence of 7 and 2.6% males in Echiniscus mauccii Ramazzotti, 1956 (North America) (McInnes, 1994) and males have never been reported, so predominantly parthenogenetic reproduction is therefore likely (Jørgensen et al, 2007). Passive wind dispersal of tardigrades has been demonstrated by Janiec (1996), and long range dispersal was suggested based on molecular data by Jørgensen et al (2007).…”

An overview of the sexual dimorphism in Echiniscus (Heterotardigrada, Echiniscoidea), with the description of Echiniscus masculinus sp. nov. (the virginicus complex) from Borneo

“…The first observations on sexual dimorphism within Echiniscidae were documented by Dastych (1987) and Kristensen (1987). At present, males have been reported for 14 echiniscid genera: Antechiniscus (Claxton 2001), Barbaria (Miller et al 1999;Michalczyk and Kaczmarek 2007), Bryodelphax (Gąsiorek and Degma 2018), Claxtonia (Kaczmarek and Michalczyk 2002;Mitchell and Romano 2007), Cornechiniscus (Dastych 1979), Diploechiniscus (Vicente et al 2013), Hypechiniscus (Kristensen 1987), Mopsechiniscus (Dastych 2001), Novechiniscus (Rebecchi et al 2008), Proechiniscus (Kristensen 1987), Pseudechiniscus (Cesari et al 2020, Stellariscus (Gąsiorek et al 2018b), Testechiniscus (Gąsiorek et al 2018a, and Echiniscus. Sexual dimorphism can be obvious, as in Mopsechiniscus, or restricted to different gonopore shapes (e.g.…”