Arthropod Systematics & Phylogeny 137 67 (2) 137 – 158 © Museum für Tierkunde Dresden, eISSN 1864-8312, 25.08.2009 Tanaidacean Phylogeny – the Second Step: the Basal Paratanaoidean Families (Crustacea: Malacostraca) GRAHAM J. BIRD 1 & KIM LARSEN 2 1 Valley View, 8 Shotover Grove, Waikanae, Kapiti Coast, 5036, New Zealand [[email protected]] 2 Programa de Pós-Graduação em Oceanografi a do Departamento de Oceanografi a Universidade Federal de Pernambuco, Av. Arquitetura, S/N, 50740-550, Recife, Pernambuco, Brasil Present address: CIIMAR, University of Porto, Rua dos Bragas, n.289, 4050-123 Porto, Portugal [[email protected]] Received 09.ii.2009, accepted 24.v.2009. Published online at www.arthropod-systematics.de on 25.viii.2009. > Abstract Phylogenetic relationships between the basal (or less derived) families in the tanaidacean superorder Paratanaoidea are examined and their monophyly tested using evidence derived from external morphology. With the genus Zeuxoides from the superfamily Tanaidoidea as outgroup, monophyly is confi rmed for the Paratanaidae, Pseudotanaidae, Pseudozeuxidae, and Typhlotanaidae. The subfamily Teleotanainae is raised to family status to accommodate the genus Teleotanais. The monophyly of Leptocheliidae s.str. is accepted but several taxa are not included, neither is monophyly verifi ed for Hetero- tanainae and Leptocheliinae. Nototanaidae appears to be polyphyletic and is split into Nototanaidae s.str. and Tanaissuidae fam. nov. Cryptocopidae is recognized but with exclusion of the Iungentitanainae; otherwise, this family is left for later analysis, including more derived taxa. Protanaissus, Leptochelia, Pseudoleptochelia and Pseudonototanais all appear to be non-monophyletic and will need revisions, while Antiplotanais, Grallatotanais, Metatanais, and Tangalooma are considered ‘fl oating’ taxa, albeit close to existing family-level clades. Initial attempts to include the derived tanaidacean families proved inconclusive and this suggests that limited phylogenetic analyses of the Paratanaoidea are necessary. We here suggest a re- vised method – the ‘Restricted taxa analysis’ – for resolving diffi cult datasets of the ‘many-taxa-few-characters’ type. This study should be regarded as a platform for more comprehensive analyses and systematic conclusions for the Tanaidacea. > Key words Phylogenetic analysis, Tanaidacea, plesiomorphic Tanaidomorpha, Tanaissuidae, Teleotanaidae, Restricted taxa analysis. 1. Introduction The phylogeny of the paratanaoid Tanaidacea was several phylogenies on the Apseudomorpha and in- last revised in 2002 in the fi rst explicit use of com- ferred the least derived tanaidacean genus to be Gi- puter-assisted parsimony methods (LARSEN & WILSON gantapseudes Gamô, 1984. He also resolved the more 2002). This was still weakly developed and incom- derived Apseudomorpha but not in an all-inclusive plete (LARSEN 2005) and even deemed controversial by analysis (SIEG 1984). No other attempts have been some workers (BAMBER 2005; BŁAŹEWICZ-PASZKOWYCZ made to revise the Apseudomorpha using phyloge- 2007). The earliest phylogenies presented by SIEG netic methods. (1984) employed the ‘bauplan/ground-plan’ principle Since the Neotanaidomorpha consists of only one that is no longer considered adequate for modern phy- family, phylogenetic treatment of this taxon is not logenetic studies; in these, he abandoned the previ- dealt with in this paper. At the present time, a con- ous division of the Tanaidacea into Monokonophora sensus exists that, in phenetic terms, it occupies a po- and Dikonophora and divided it into three Recent sition intermediate between the Apseudomorpha and suborders (Apseudomorpha, Neotanaidomorpha and Tanaidomorpha (LANG 1956; GARDINER 1975; SIEG Tanaidomorpha) and the extinct Anthracocaridomor- 1983; KUDINOVA-PASTERNAK 1985; SIEG 1988; LARSEN pha. SIEG (1984) went further into the suborders with & WILSON 2002). 138 BIRD & LARSEN: Phylogeny of basal Paratanaoidea The Tanaidomorpha is by far the largest subor- of a genus). On the other hand, this new analysis is der (currently containing 15 families, 127 genera and limited to the ‘basal’ families in order to keep the ra- more than 75% of all known tanaidacean species) and tio of taxa to characters low, a pragmatic approach it is where the highest diversity is found. The mem- that does not imply that there should be a strict rela- bers of this taxon are also the smallest tanaidaceans, tionship between number of characters and terminal characterised by many setal reductions and segmental taxa, i.e. full resolution of all family relationships is fusions that further complicate the systematics. SIEG not intended. It should be regarded as the fi rst of sev- (1984) provided an all-encompassing phylogeny of the eral new attempts to improve resolution and consist- Tanaidomorpha but the systematics changed continu- ency in tanaidomorphan systematics. Yet, impeding ously almost immediately following this publication. or restricting analyses of tanaidacean phylogeny are Sieg himself continued to make changes in the com- the perceived lack of ‘good’ characters due to reduc- position of the more derived families (Agathotanaidae, tions, signifi cant inter-taxa variation (as seen by cur- Anarthruridae and Leptognathiidae) and, despite that rent taxonomy), confusing setal forms and a multitude the Leptognathiinae and Typhlotanainae did not con- of homoplasies (LARSEN & WILSON 2002; GUERRERO- stitute monophyletic groups in his own phylogeny, he KOMMRITZ & BRANDT 2005). The conservative or con- combined them in the family Leptognathiidae. That vergent morphology of the numerous tanaidomorphan family was later the focus of multiple alterations and genera, particularly in the deep sea, remains an obsta- recombinations (BIRD & HOLDICH 1984; SIEG 1986a,b) cle to phylogenetic resolution. The lack of knowledge but, again, without phylogenetic analysis. The constant about the male gender of many of these genera is a altering of the taxa and diagnoses of this family group further complication. Males are especially unknown in resulted in confused systematics. Subsequent workers species-rich deep-sea assemblages and, if they are of tended to use Leptognathiidae as a repository whenever the natatory form, they generally remain listed as ‘in- they described a new tanaidacean that did not fi t any es- determinate’. In this paper a method, the ‘Restricted tablished family. In the deep sea, this amounts to about taxa analysis’ is suggested to help overcome these ob- 50% of all tanaidomorphan species. This unfortunate stacles. Clearly, the identifi cation and refi ning of test- fact has haunted tanaidacean systematics ever since. able characters remains an imperative and is ongoing. Of the two superfamilies in the Tanaidomorpha, Tanaoidea and Paratanaoidea, only the latter was af- fected substantially by LARSEN & WILSON (2002); since then, the systematics have further changed rapidly with 2. Materials and methods close to 40 new genera and hundreds of new species described. Again, many shifts in tanaidacean system- atics have been introduced without phylogenetic ana- 2.1. Ingroup lysis (GUTU & HEARD 2002; GUTU 2006; BŁAŹEWICZ- PASZKOWYCZ 2007). Only two papers (GUERRERO-KOMM- The ingroup is made up of 57 taxa, mostly genera or RITZ & BRANDT 2005; LARSEN & SHIMOMURA 2008), subgenera, from what are perceived to be the most one dissertation (MCLELLAND 2008) and one confer- basal to mid-level families in the paratanaoidean tree ence poster (BŁAŹEWICZ-PASZKOWYCZ & POORE 2008) (see Tab. 1 for these and authorities). Fortunately, just employed computer-assisted phylogenetic methods to prior to submission of this study, a paper describing the Tanaidacea. The study of GUERRERO-KOMMRITZ & two new relevant genera (Antiplotanais, Typhlotan- BRANDT (2005) was restricted to the Akanthophoreinae aidae and Catenarius, Leptocheliidae) was published and the authors wisely abstained from making major by BAMBER (2008) but time constraints prevented the systematic conclusions. The analysis by LARSEN & inclusion of the new Leptochelia species in the present SHIMOMURA (2008) dealt only with the Nototanaidae analysis. All relevant species were included to pro- s.str. (with leptocheliid outgroups) and had an equally duce a character scoring for each nominal genus as restricted hypothesis. The poster of BLAZEWICZ-PASZ- a terminal taxon but, as initial data from the charac- KOWYCZ & POORE (2008) included the more derived, ter analysis revealed considerable polymorphism in non-paratanaoid, taxa but did not resolve most of these. certain genera (e.g. Leptochelia, Pseudoleptochelia, What was resolved operated with bootstrap support to Pseudonototanais and Protanaissus) these were sub- as low as 53%, further highlighting the problems with divided as necessary (see Tab. 1) into what appeared to homoplasy in tanaidacean phylogenies. be more ‘natural’ groups. Using several more realistic, The present study is a follow-up on the LARSEN & polymorphism-light taxa was considered preferable to WILSON (2002) phylogenetic analysis, including all one clearly polyphyletic genus. The two subgenera of species in the character evaluation and is thus not re- Pseudotanais G.O. Sars were also treated separately stricted to the ‘exemplar approach’ as used there (i.e. and this is supported by a recent study by MCLELLAND use of one well-described species or the type species (2008). Arthropod Systematics & Phylogeny 67 (2) 139 Tab. 1. Taxa included in the analysis. Existing taxa that did not appear in LARSEN & WILSON