Glime, J. M. 2017. Invertebrates: Rotifer Taxa – Monogononta. Chapt. 4-7a. In: Glime, J. M. Bryophyte Ecology. Volume 2. 4-7a-1 Bryological Interaction. Ebook sponsored by Michigan Technological University and the International Association of Bryologists. Last updated 18 July 2020 and available at <http://digitalcommons.mtu.edu/bryophyte-ecology2/>. CHAPTER 4-7a INVERTEBRATES: ROTIFER TAXA – MONOGONONTA TABLE OF CONTENTS CLASS MONOGONONTA ............................................................................................................................. 4-7a-2 Order Collothecacea ................................................................................................................................... 4-7a-2 Collothecidae ...................................................................................................................................... 4-7a-2 Collotheca .................................................................................................................................... 4-7a-3 Stephanoceros .............................................................................................................................. 4-7a-5 Order Flosculariacea .................................................................................................................................. 4-7a-6 Conochilidae ....................................................................................................................................... 4-7a-6 Flosculariidae ...................................................................................................................................... 4-7a-7 Floscularia ................................................................................................................................... 4-7a-7 Ptygura ........................................................................................................................................ 4-7a-8 Hexarthridae...................................................................................................................................... 4-7a-10 Testudinellidae .................................................................................................................................. 4-7a-11 Order Ploimida ......................................................................................................................................... 4-7a-13 Trochosphaeridae .............................................................................................................................. 4-7a-14 Brachionidae ..................................................................................................................................... 4-7a-15 Anuraeopsis ............................................................................................................................... 4-7a-15 Brachionus ................................................................................................................................. 4-7a-16 Kellicottia .................................................................................................................................. 4-7a-16 Keratella .................................................................................................................................... 4-7a-17 Notholca ..................................................................................................................................... 4-7a-19 Dicranophoridae ................................................................................................................................ 4-7a-19 Albertia ...................................................................................................................................... 4-7a-20 Aspelta ....................................................................................................................................... 4-7a-20 Dicranophorus ........................................................................................................................... 4-7a-21 Dorria ........................................................................................................................................ 4-7a-24 Encentrum .................................................................................................................................. 4-7a-24 Pedipartia .................................................................................................................................. 4-7a-26 Streptognatha ............................................................................................................................. 4-7a-26 Wierzejskiella ............................................................................................................................. 4-7a-27 Epiphanidae ...................................................................................................................................... 4-7a-27 Cyrtonia ..................................................................................................................................... 4-7a-27 Epiphanes .................................................................................................................................. 4-7a-27 Mikrocodides ............................................................................................................................. 4-7a-28 Euchlanidae ....................................................................................................................................... 4-7a-28 Gastropodidae ................................................................................................................................... 4-7a-32 Summary ......................................................................................................................................................... 4-7a-33 Acknowledgments ........................................................................................................................................... 4-7a-33 Literature Cited ............................................................................................................................................... 4-7a-33 4-7a-2 Chapter 4-7a: Invertebrates: Rotifer Taxa – Monogononta CHAPTER 4-7a INVERTEBRATES: ROTIFER TAXA – MONOGONONTA Figure 1. Keratella sp. among Sphagnum leaves. Photo by Marek Mis <www.mismicrophoto.com>, with permission. CLASS MONOGONONTA ORDER COLLOTHECACEA Many members of this order are sessile (attached) and This is the largest of the two classes of rotifers, some are colonial. These rotifers have a foot that lacks comprised of ~1570 species, ~1488 of which are free-living toes, but they possess many foot glands that are used for in fresh water of limnoterrestrial habitats (Segers 2008). It adhesion. The females are predominantly sessile, but differs from the Bdelloidea in having two sexes and having males and immature rotifers are free-living.. The rotary only one ovary. Nevertheless, asexual reproduction occurs apparatus surrounds a funnel-like invagination. Many are over and over until environmental conditions, often related surrounded with a jelly sheath. to crowding, trigger the reproduction to become sexual (Welch 2008). At this time, the eggs of the amictic (non- sexual) females hatch into mictic females that produce Collothecidae their eggs by meiosis. The haploid eggs that are not Many members of the Collothecidae are plant and fertilized develop into much smaller males and fertilization algal inhabitants. The Collothecidae provide us with of a female by these males produces diploid eggs that evidence of adaptive strategies embodied in reproduction. become resting eggs. An examination of 65 species of rotifers, including this The monogonont rotifers mostly eat small particles and family, revealed that egg volume of rotifers increased as organisms by filtering them, some actually seize them, and body volume increased, but the relative size of eggs some are parasitic. actually decreased as body size increased (Wallace et al. Chapter 4-7a: Invertebrates: Rotifer Taxa – Monogononta 4-7a-3 1998). This means that smaller species, typical among planktonic species and bryophytes, invest the most in egg production. The Flosculariidae (Flosculariacea) species are of intermediate size and their relative investment in egg mass is likewise intermediate. The Collothecidae family has the largest species and the lowest relative biomass of egg production among those examined by Wallace et al. Collotheca Collotheca (Figure 2-Figure 8) is a common genus in peatlands, living in Sphagnum pools (Figure 5) and on Sphagnum (Figure 2, Figure 21, Figure 61-Figure 62). Figure 4. Collotheca sp., a common genus on Sphagnum. Photo by Yuuji Tsukii, with permission. Figure 5. Sphagnum pond, home for rotifers. Photo by Michael Luth. Collotheca campanulata occurs on wet mosses as well as in the plankton on Svalbard (De Smet 1993). The relationships of this species to aquatic flowering plants can Figure 2. Collotheca on Sphagnum. Photo by Marek Mis instruct us on relationships to look for among bryophytes. <www.mismicrophoto.com>, with permission. Collotheca campanulata (gracilipes) (Figure 6) is selective in its location on its aquatic plant substrate (Wallace & Edmondson 1986). On plants such as Elodea canadensis, it selected (98%) the lower (abaxial) surfaces of the leaves. When given equal opportunities for four plant species, it selected Lemna minor over Elodea canadensis, but in the field more