Gastrotrichs from interstitial fresh water, with a description of four new species

Abstract

A study was performed on freshwater gastrotrichs living in the interstitial habitat of some lakes in Latium and of Lake Garda (Italy) . Thirty-two chetonotids were collected, twenty-five of which could be identified . Four are new to science (Chaetonotus (Hystricochaetonotus) benacensis, Heterolepidoderma lamellatum, Ichthydium plicatum, I. squamigerum), and two are new to the Italian fauna (Heterolepidoderma macrops, H . majus) . The faunistic composition of the lakes is compared with previous data . Interstitial gastrotrichs are less varied and abundant than those of epibenthos and periphyton, but often are of taxonomical and zoogeographical interest . The presence in the interstitial of some epibenthic and periphytic species demonstrates their capacity to colonize ecologically different habitats . The grain size of the substrate was not clearly correlated with faunal richness, but there was a possible influence of the amount of the organic detritus in the sediment . Morphological analysis showed a prevalence of small sized animals, with poorly ornamentated cuticular covering and well developed locomotory ciliature, as probable adaptations to interstitial life .Abbreviations : b = dorsal sensory bristles ; d = dorsal ; dl = dorsolateral ; f = furca ; h = head ; n = neck ; L = length ; T L = total length ; lat = lateral ; ph = pharynx ; p1= ventral terminal plates ; v = ventral scale/s ; sp = spine/s ; spec = specimens ; tr = trunk ; v = ventral ; w = width .

Limnological research in the deep southern subalpine lakes: synthesis, directions and perspectives

“…A few studies have focused on recent new introductions of shrimps and molluscs in Lake Garda (Dikerogammarus villosus [144]; Corbicula fluminalis and C. fluminea [146]), and on the identification of new species of Gastrotrichs (Lake Garda [143]). …”

An Overview of Studies on Meiofaunal Traits of the Littoral Zone of Lakes

“…Rather, there may be intrinsic difficulties, often insurmountable, such as those related to the movements of these tiny organisms within the hidden benthic and inbenthic world made of sand grains, interstitial pores, biofilms and detrital particles, that make direct observations difficult in the natural environment (e.g., [19,23]). The same difficulties were due to the scarcity of studies related to the "locomotion and substrate relation" trait which has been investigated almost exclusively in nematodes, rotifers, some crustaceans and gastrotrichs e.g., [55,56]. Majdi et al [21] suggested using laboratory populations with mesocosms to study certain traits that otherwise would not be directly observable in the field e.g., [57,58].The results obtained also indicate that the traits receiving the least interest are respiration and thermal preference.…”

A new species of freshwater Chaetonotidae (Gastrotricha, Chaetonotida) from Obodska Cave (Montenegro) based on morphological and molecular characters

“…Out of ca 40 species found in sandy biotopes, fewer than 10 seem to constitute exclusively interstitial taxa (Balsamo et al 2015). All of the species share certain morphological traits, e.g., a small body size, a poorly ornamented cuticular covering, a well developed locomotory ciliature and adhesive organs (Balsamo & Fregni 1995;Balsamo et al 2015). Entire sets of these characteristics also occur in C. (C.) antrumus sp.…”