Five new species of <i>Monocelis</i> Ehrenberg, 1831 (Platyhelminthes: Proseriata) from eastern Australia

Six species of the genus Monocelis Ehrenberg, 1831 have been found in eastern Australia. All are new to science. Five of them are formally described here. Three species (M. rupisrubrae sp. nov., M. nexilis sp. nov., and M. corallicola sp. nov.) have two clearly set pigmented eyespots lateral to the statocyst. They differ in details of the copulatory organ and karyotype. No clear synapomorphies among them or with other species of the genus could be detected. Monocelis beata sp. nov. and M. macrobulbus sp. nov. present extremely elongate, longitudinally oriented copulatory organs. They are sister species, and phylogenetic relationships with M. galapagoensis Ax and Ax, 1977 and M. hopkinsi Karling, 1966 are proposed. Australian Monocelis have distributions limited to recognized biogeographical provinces in eastern Australia: M. corallicola, M. beata and M. macrobulbus in the northern Australian Zone, M. rupisrubrae and M. nexilis in the 'Overlap Zone' of the central east coast and Monocelis sp. A in the southern Australian Region

The genus <i>Minona</i> (<i>Platyhelminthes</i>, Seriata) in eastern Australia

Four new species of the genus Minona Marcus, 1946 from eastern Australia are described. Minona proculvaginata sp. n., M. australis sp. n. and M. concharum sp. n. have four genital pores, and differ in details of the copulatory organs. The epidermis of these three species is unciliated in a ventral area around the male pore. Based on this synapomorphic feature, they are sister species. The karyotype of M. proculvaginata and M. concharum is described. Minona heronensis sp. n. is distinct from congeneric species on the basis of the size of its accessory stylet and copulatory organ, pore indices and karyotype. It is compared to numerous similar Indo-Pacific species. Additional data on the anatomy and karyology of M. beaglei Martens &amp; Curini-Galletti, 1989 from N. Australia, are given. One specimen from Heron Island is tentatively attributed to M. dolichovesiculu Tajika, 1982 a species widely distributed in the Indo-Pacific. Its karyotype is given

A Polypharyngeal marine flatworm (<i>Platyhelminthes</i>, <i>Proseriata</i>, <i>Archimonocelididae</i>) from eastern Australia

Archimonocelis medusa sp. nov. is described from eastern Australia. The species is characterized by numerous (15–25) pharynges, as well as by details of sclerotized organs and karyotype. It is the first polypharyngeal marine flatworm known, and the first record of polypharyngy outside the Tricladida. Polypharyngy is interpreted as a disruption of the processes of pharyngeal induction and inhibition during development. Its possible adaptiveness is discussed

The Temnocephalidae (Platyhelminthes): molecular data illuminate the evolution of an ancient group of symbiotic flatworms

The Temnocephalidae sensu Van Steenkiste et al., 2021 is a diverse group of rhabdocoel flatworms that are ectosymbiotic mostly on freshwater crustaceans. The family is found on all inhabited continents except for N. America (north of Mexico) and Africa. Here, we explore the systematic implications of a molecular phylogeny inferred from partial sequences of the nuclear 18S and 28S ribosomal RNA genes. In agreement with previous views based on morphology, the earliest diverging group within the family was exemplified by the genus Scutariella (subfamily Scutariellinae) followed by the genus Didymorchis (Didymorchinae). The genus Dactylocephala from Madagascar, previously thought to be in the Temnocephalinae, then diverged as sister to the remaining temnocephalids. A new subfamily, Dactylocephalinae, is proposed to contain this genus. Remaining subfamilies were, in turn, Diceratocephalinae, Actinodactylellinae and Temnocephalinae. Further subdivision was apparent within the Temnocephalinae. One well-supported clade included the genera Temnohaswellia (eastern Australia and New Zealand), Temnomonticellia (Tasmania) and Temnocephala (South America). The widespread genus Temnosewellia (= Ts.) was not supported as monophyletic. One clade of Temnosewellia sensu lato included numerous species known primarily from crayfish of the genus Euastacus, found in eastern and south-eastern Australia. Two other clades circumscribed the taxa Ts. minor and Ts. dendyi. Identities and membership of these two clades are clouded by frequent misidentifications, the reasons for which are discussed here. A fourth clade of Temnosewellia s.l. included Ts. rouxi and other taxa from northern Australia and Asia (ranging at least from Japan to India). The diversity of temnocephalids in Australia, and especially in Asia, is greatly underappreciated. Some general comments are made about geographic distribution of temnocephalids, but detailed biogeographic analysis requires broader sampling