Phylogeny of the taxon Paralaophontodes Lang (Copepoda, Harpacticoida, Laophontodinae), including species descriptions, chorological remarks, and a key to species

First report of the genus Bicorniphontodes (Copepoda, Harpacticoida, Ancorabolidae) in South Korea, with descriptions of three new species

We report the occurrence of the genus Bicorniphontodes George, Glatzel & Schröder, 2019 in Korean waters, with descriptions of three new species: Bicorniphontodes lacuna sp. nov., B. comptus sp. nov., and B. huysi sp. nov. Morphology analysis was carried out to reconstruct the phylogenetic relationships of Bicorniphontodes species, including the three new species. Parsimony analysis based on 41 characters revealed that the three new species are clustered together as a monophyletic clade, of which B. horstgeorgei (George & Gheerardyn, 2015) is a sister species. The monophyletic status of three new species was supported by five synapomorphies, such as the micro-morphological conditions of the exopodal segments of the first leg, coxae of the second to fourth legs, exopod of the fifth leg in the female and baseoendopod of the fifth leg in the male, and the maxillular endopod represented by two setae. These three species can be easily distinguished based on the morphology of the rostrum, cephalothoracic processes, female genital double-somite, caudal rami, and second endopodal segment of the third leg in the male. The taxonomic position of B. bicornis sensu Kim, 2013 in Korean fauna was reevaluated based on the newly collected material from Udo Islet near Jeju Island; this resulted in a synonym of B. huysi sp. nov.

Revision of the genus Laophontodes T. Scott (Copepoda, Harpacticoida, Ancorabolidae), including the description of a new species and a key to species

The description of Laophontodes volkerlehmanskii sp. nov. (Copepoda, Harpacticoida, Laophontodinae Lang) from the deep sea of the Kairei Field, western Indian Ocean, prompted the examination of the phylogenetic status of Laophontodes T. Scott and the relationships within the genus. The allocation of L. volkerlehmanskii sp. nov. to Laophontodes based on diagnostic characters was relatively straightforward, yet phylogenetic analysis of the genus considering 39 morphological characters detected not a single autapomorphy. This indicates that Laophontodes, which seems to form a monophylum with Ancorabolina George and Bicorniphontodes George, Glatzel & Schröder, actually represents the stem-lineage, retaining the characters of the common ancestor without having developed unique derived morphological characters. Most of the 13 known species of Laophontodes can be characterised by distinct apomorphies. However, phylogenetic comparison highlights some uncertainties due to the apparent heterogeneous distribution of some derived characters across the species, the weakness of other features, and the fragmentary and inadequate description of several species, which, in combination with the unavailability of type material, prevents a detailed comparison of several phylogenetically relevant characters. Thus, the analysis presented here provides a further step towards understanding the systematic relationships of and within Laophontodes, rather than a conclusive answer. Nonetheless, a detailed character discussion and a key to species are given.

Restructuring the Ancorabolidae Sars (Copepoda, Harpacticoida) and Cletodidae T. Scott, with a new phylogenetic hypothesis regarding the relationships of the Laophontoidea T. Scott, Ancorabolidae and Cletodidae

Uncovering the systematics of CopepodaHarpacticoida, the second-most abundant component of the meiobenthos after Nematoda, is of major importance for any further research dedicated especially to ecological and biogeographical approaches. Based on the evolution of the podogennontan first swimming leg, a new phylogenetic concept of the Ancorabolidae Sars and Cletodidae T. Scott sensu Por (Copepoda, Harpacticoida) is presented, using morphological characteristics. It confirms the polyphyletic status of the Ancorabolidae and its subfamily Ancorabolinae Sars and the paraphyletic status of the subfamily Laophontodinae Lang. Moreover, it clarifies the phylogenetic relationships of the so far assigned members of the family. An exhaustive phylogenetic analysis was undertaken using 150 morphological characters, resulting in the establishment of a now well-justified monophylum Ancorabolidae. In that context, the Ancorabolus-lineage sensu Conroy-Dalton and Huys is elevated to sub-family rank. Furthermore, the membership of Ancorabolina George in a rearranged monophylum Laophontodinae is confirmed. Conversely, the Ceratonotus-group sensu Conroy-Dalton is transferred from the hitherto Ancorabolinae to the Cletodidae. Within these, the Ceratonotus-group and its hypothesised sister-group Cletodes Brady are combined to form a monophyletic subfamily Cletodinae T. Scott, subfam. nov. Consequently, it was necessary to restructure the Ancorabolidae, Ancorabolinae and Laophontodinae and extend the Cletodidae to include the displacement and exclusion of certain taxa. Moreover, comparison of the Ancorabolidae, Cletodidae, Laophontoidea and other Podogennonta shows that the Ancorabolidae and Cletodidae form sister-groups in a monophylum Cletodoidea Bowman and Abele, which similarly has a sister-group-relationship with the Laophontoidea T. Scott. According to the present study, both taxa constitute a derived monophylum within the Podogennonta Lang.

New Ancorabolidae (Copepoda: Harpacticoida) from Korea: two new genera, revisionary notes and updated identification keys

Two new copepod species of the Ceratonotus group in the subfamily Ancorabolinae (Ancorabolidae) are described from the Korean peninsula. Dendropsyllus kimi sp. nov. differs from its congeners by the one-segmented ♀ P3 endopod, the inner spine on ♀ P5 exopod and the absence of sensillate tubercles on abdominal somites 1 and 2. Dimorphipodia gen. nov. is proposed to accommodate Dimorphipodia changi sp. nov. and can be differentiated from its sister taxon, Arthuricornua, by the sexual dimorphism in P2–P4 exp-3, the absence of paired laterodorsal processes near the posterior margin of the cephalothorax and the presence of pleural setular tufts on somites bearing P2–P4. Ancorabolina, previously placed in the Ancorabolinae, is transferred to the Laophontodinae, whereas Patagoniaella is provisionally reassigned to the family Cletodidae. Within Laophontodes, the inadequately described Laophontodes brevis, Laophontodes ornatus and Laophontodes propinquus are relegated to species inquirendae. Laophontodes georgei sp. nov. is proposed for the unavailable name Laophontodes norvegicus, Laophontodes multispinatus is reassigned to Lobopleura, and Laophontodes gracilipes is fixed as the type of Rostrophontodes gen. nov., the potential sister group of Ancorabolina. The authenticity of Laophontodes bicornis and other dubious ancorabolid records from the Korean peninsula is discussed. Updated keys to genera of both Ancorabolinae and Laophontodinae and to species of Laophontodes are provided.

Phylogenetic incongruence and homoplasy in the appendages and bodies of arthropods: why broad character sampling is best

Notwithstanding the rapidly increasing sampling density of molecular sequence data, morphological characters still make an important contribution to our understanding of the evolutionary relationships of arthropod groups. In many clades, characters relating to the number and morphological specialization of appendages are ascribed particular phylogenetic significance and may be preferentially sampled. However, previous studies have shown that partitions of morphological character matrices often imply significantly different phylogenies. Here, we ask whether a similar incongruence is observed in the appendage and non-appendage characters of arthropods. We apply tree length (incongruence length difference, ILD) and tree distance (incongruence relationship difference, IRD) tests to these partitions in an empirical sample of 53 published neontological datasets for arthropods. We find significant incongruence about one time in five: more often than expected, but markedly less often than in previous partition studies. We also find similar levels of homoplasy in limb and non-limb characters, both in terms of internal consistency and consistency relative to molecular trees. Taken together, these findings imply that sampled limb and non-limb characters are of similar phylogenetic utility and quality, and that a total evidence approach to their analysis is preferable.