Abstract
Maldanids are usually divided into several subfamilies: Euclymeninae, Lumbriclymeninae, Maldaninae, Nicomachinae, Rhodininae, Clymenurinae, Notoproctinae, and Boguinae. The taxonomy of maldanids and the delimination of these taxa are mainly based on head morphology, total number of segments, chaetal structure, shape of the pygidium, and position of the anus. The maldanid ingroup relationships, as well as the monophyly of the proposed subfamilies, have so far not been investigated. Pilgrim (1977) described a shift of the notopodial chaetal rows from a transverse direction in anterior chaetigers to a more longitudinal one in posterior chaetigers in Clymene torquata (Leidy, 1855) and Euclymene oerstedii (Claparede, 1863), both belonging to the Euclymeninae. We investigated several maldanid species to assess the usefulness of this character for maldanid systematics and used 3D-reconstruction techniques to reveal the complete geometry of the chaetal sacs. Our investigation shows that a shift is apparent in Euclymene, Axiothella, Johnstonia (all Euclymeninae) and Clymenura (Clymenurinae), but absent in species like Maldane sarsi (Malmgren, 1865), Metasychis disparidentata (Moore, 1904) (both Maldaninae) and Petaloproctus borealis Ardwisson, 1906 (Nicomachinae). The shift is not typical for sedentary polychaetes and is apomorphic within maldanid polychaetes. It thus argues for a close relationship between Euclymeninae and Clymenurinae. The investigation of further maldanid species of different subfamilies may shed additional light on maldanid systematics.
Highlights
Maldanids, the so called “bamboo-worms”, comprise a group of tubicolous burrowers
Pilgrim (1977) described a shift of the notopodial chaetal rows from a transverse direction in anterior chaetigers to a more longitudinal one in posterior chaetigers in Clymene torquata and Euclymene oerstedii, both belonging to the Euclymeninae
In the present study we investigated the presence of this shift in chaetal arrangement to assess its usefulness for maldanid ingroup systematics
Summary
The so called “bamboo-worms”, comprise a group of tubicolous burrowers. More recently Clymenurinae (Imajima and Shiraki, 1982) and Notoproctinae (Detinova, 1985) have been proposed. A taxon originally described as an oweniid (Hartman, 1945), has been transferred to Maldanidae (Wolf, 1983). The delimitation of these taxa, and the systematics of the family, are mainly based on head morphology, total number of segments, chaetal structure, shape of the pygidium, and position of the anus (Rouse and Pleijel, 2001). The maldanid ingroup relationships, as well as the monophyly of the proposed “subfamilies” have as yet not been investigated
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