Haplotaxoides Fend 2024, gen. nov.

Haplotaxoides Fend gen. nov. ZooBank LSID: urn:lsid:zoobank.org:act: A4B96C04-5B05- 4B0C-B92D-16CB89A95516 Synonyms: Haplotaxis Hoffmeister (partim) in Brinkhurst 1966; Brinkhurst and Jamieson 1971: 286; not Hoffmeister 1843. Type species: Haplotaxoides decipiens Fend sp. nov. Etymology Morphologically similar to (Latin, - oides) Haplotaxis. Diagnosis Body form narrow and elongate, body wall with thick cuticular layer, peristomium elongate, extending well anterior to the mouth. Secondary annulation present from V. Brain anterior to mouth in peristomium. Ventral chaetae large, single, with a straight shaft and strongly hooked distally, simple-pointed, but may have a dorsal keel; dorsal chaetae small, single, present in all segments from II. Buccal-pharyngeal region thickened dorsally, with radial muscle bands extending to the body wall, interspersed with longitudinal and circular muscle bands surrounding gut. Oral cavity reduced to II, not extensive; a sleeve of circular muscles surrounds pharynx in II– III; conspicuous pharyngeal glands absent; gut wall in pharyngeal area not highly muscular. Nephridia present in all middle and posterior segments; ducts with large, irregular cells, forming a compact mass filling much of the segment. Dorsal and ventral blood vessels connected by simple commissural vessels. Conspicuous, ovate coelomocytes usually present in all segments. In III and onward, all segments with 3 (2) elongate, transparent to granular glands inserting between ventral chaetae with external secretory patches; smaller glands may be present in I and II. Spermathecae possibly present but structure and number at maturity unknown. Paired testes in XII and XIII, one pair of ovaries in XV. Gonoducts simple. Modified genital chaetae in at least one species. Remarks This new genus is referred to its own, monotypic, family, Haplotaxoididae fam. nov., and for the time being, the diagnosis of Haplotaxoides is identical to that of the family. For comparisons with other genera, see ‘General remarks on Haplotaxoides material’ below. All of the analysed Haplotaxoides material, as well as most collections of morphologically similar specimens (see below), are from the western Nearctic region. Two groundwater records indicate that the genus also occurs in central North America (see below: ‘Other Haplotaxoides material (not analysed for DNA)’). In the material used for molecular analysis, we seem to have five distinct species of Haplotaxoides, all from the western USA (seeFig. 1). However, we conclude that only for two of them, the available material is sufficient for formal description of (named) new species; see below. For the three others (spp. A–C), we present preliminary morphological observations only.