Haplotaxida

Abstract: Phylogenetic relationships between five subfamilies of Tubificidae and ten other families of microdrile oligochaetes were estimated by a Wanger parsimony analysis using PAUP (Phylogenetic Analysis Using Parsimony, by D. L. Swofford). As the apomorph character state is ambiguous for some characters, different assumptions of directionality as well as deletions of some characters are tested in a number of analyses. A general pattern is evident from the study; (1) the majority of the aquatic families are members of a large monophyletic group (the order Tubificida in a somewhat restricted sense) defined by the shared possession of atria (generally with well developed external prostate glands), but the family Tubificidae is paraphyletic within this group; (2) the Enchytraeidae appear to form a second group (the ‘Enchytraeida’) together with the exclusively marine Capilloventridae and Randiellidae, all three families characterized by the anterior location of the spermathecae; (3) the Haplotaxidae are a plesiomorph family, which stands out as a branch of its own and constitutes the ‘ancestral’ part of a group comprising also all the megadriles (the Haplotaxida). However, monophyly of the Haplotaxida is likely only if the haplotaxid octogonadial condition is assumed to be derived from the tetragonadial condition characterizing most microdriles, a situation not envisaged by previous authors. The implications of the parsimony method are briefly discussed.

Abstract: The Haplotaxidae have all the characteristics to support the hypothesis that they are the living descendents of the stem forms from which all of the Oligochaeta Clitellata (Orders Lumbriculida, Haplotaxida, Lumbricida, Tubificida) can be derived. The Aphanoneura are distinct from the Clitellata and are raised to a separate Class. There is no evidence to support the view that the elaborate setae of many Tubificida are derived from a polychaete ancestry; both are held to be independent modifications to aquatic life derived from a simple burrowing protoannelid with lumbricine setae.

Abstract: Two of the three orders into which the Oligochaeta (earthworms and their allies) are divisible (Brinkhurst & Jamieson, 1971) are represented in Tasmania (for classification see Table 8.1). The primitive order Lumbriculida is represented by a single species, the cosmopolitan and probably anthropochorous Lumbriculus variegatus, while the remainder of the known oligochaete fauna consists of many species of the order Haplotaxida. The only ‘microdrile’ families of the Haplotaxida known on the island are the Tubificidae and Phreodrilidae. The four tubificids are two endemic species, Telmatodrilus multiprostatus and T. pectinatus, and Antipodrilus davidis, which also occurs in Australia and New Zealand, and the cosmopolitan Limnodrilus udekemianus (see Brinkhurst, 1971). The only named phreodrilid is the species inquirenda Tasmaniaedrilus tasmaniaensis.