Records of the Western Australian Museum 21: 235-267 (2002). A systematic revision of the family Harpetidae (Trilobita) Malte C. Ebach 1 and Kenneth J. McNamara 2 1 School of Botany, The University of Melbourne, Victoria 3010, Australia. 2 Department of Earth and Planetary Sciences, Western Australian Museum, Francis Street, Perth, Western Austaralia, 6000, Australia. Abstract - The systematics of the ten valid harpetid trilobite genera are reviewed. Seven are revised, using standard parsimony and three-item analysis. The monophyly of the Harpetidae is confirmed, and all ingroup genera can be defended as monophyletic groups except for the non­ monophyletic ScotolJarpes group. Emended diagnoses are provided for all the genera within the family. The three subfamilies Dolichoharpinae, Eoharpetinae and Harpetinae are supressed within the Harpetidae. The genera AlIstraloharpes and Sinoharpes are placed in synonymy with DlIbhglasina. Thorslundops and Wegeiinia are placed in synonymy with Hibbertia, and the subgenus FritclJaspis placed in synonymy with LiolJarpes. Reticuloharpes and HelioJwrpes are placed in synonymy with Harpes. The Harpetidae, along with the Entomaspididae and Harpididae, is considered to belong in the Harpetida, which is herein raised to ordinal rank within the subclass Libristoma. INTRODUCTION Woodward, 1898, Lioharpes Whittington, 1950a and The trilobite family Harpetidae Hawle and Corda, Scotoharpes Lamont, 1948a. Not included within this 1847 has been revised twice since its erection over analysis were Brachyhipposiderus Jell, 1985 and 150 years ago, firstly by Whittington (1950a) and Dolic1lOharpes Whittington, 1949, because each secondly by Pribyl and Vanek (1986). Subsequently, contain too few species to enable a cladistic analysis numerous authors (Prantl and Phbyl, 1954, Vanek, to be carried out. A cladistic analysis of Kielania 1963, Phbyl and Vanek, 1981, Piibyl and Vanek, Vanek, 1963, along with a new genus, will be 1986) have left a legacy of what we regard as presented elsewhere (Ebach and McNamara, in unnecessary subfamilies, poorly supported genera, prep.). subgenera, species and subspecies. The most recent Three-item analysis is used as the favoured revision by Phbyl and Vanek (1986), perhaps the cladistic method (Williams and Siebert in Scotland most detailed to date, indicates the enormity of the and Pennington 2000). However, due to the task involved in clearing up this 'Harpetid legacy'. implementation of the three-item method, standard For instance, one case relates to the subfamilies parsimony is included for comparison. Because of Dolichoharpetinae, Eoharpetinae and Harpetinae, the large degree of morphological variability which Piibyl and Vanek (1981) proposed. Each encompassed by the species within each genus, any subfamily, however, is loosely supported by cladistic analysis dealing with supraspecific spurious characteristics that also define members of taxonomy must be treated with caution. the other subfamilies. The Harpetidae should stand alone as a monophyletic group, or as several related clades supported by more than two or three METHODS synapomorphies each. Moreover, the past practice In cladistics it is possible to construct cladograms of assigning poorly preserved single specimens to using different methods. The most common method new species and genera is unacceptable. is standard parsimony analysis. The character-states This is the first cladistic analysis undertaken of in standard parsimony are treated as a the Harpetidae. The result is that the Harpetidae transformation series, i.e., one state transforming are characterised by synapomorphies rather than by into another. Although the use of transformation either ancestor-descendant or biostratigraphic series has its merits, its premise of transformations relationships. Of the previously described genera, is a pre-cladistic concept (Kitching et al. 1998). In seven were subjected to a cladistic analysis of their order to move away from the 'established' standard internal relationships: Bohemoharpes Vanek, 1963, parsimony analysis and into a realm in which Dubhglasina Lamont, 1948b, Eoharpes Raymond, character-states are treated as taxa (by degrees of 1905, Harpes Goldfuss, 1839, Hibbertia Jones and relationship), three-item analysis is considered to be 236 M. C. Ebach, K. J. McNamara the most appropriate method to use. Three-item resulting in either an anteriorly convex analysis finds a suite of the smallest units of deflection, or a posteriorly convex deflection; relationship, a three-item statement, for each • Anterior boss - a sagittal inflation that may character (Nelson and Platnick 1991). A series of extend from the preglabellar field onto the genal three-item statements is converted into a binary roll, and sometimes onto the brim; matrix and can then be processed using any • Sagittal crest - a narrow ridge that extends standard parsimony program. sagittally along the glabella, and effaces Three programs are necessary to implement a posteriorly; three-item analysis. MATRIX (Nelson and • Transverse preglabellar ridge - occurs as a raised, Ladiges 1995) converts the matrix into a three­ non-tuberculate region immediately anterior item matrix. TAX (Nelson and Ladiges 1995) then (sag.) to the preglabellar furrow, or as a ridge applies weights (factor = 50) to each statement that is continuous with the eye ridge; (see also Kitching et al. 1998). NONA 2.0 • Alar ridge - secondary furrow running parallel (Goloboff 1998) (max. trees = 100; mult* = 1000; to axial and alar furrows, forming prominent trees per rep = 20, TBR branch swapping), finds ridge; the most parsimonious trees. NONA excludes any • Interalar furrow - an exsagittal furrow traversing ambiguous optimisations (i.e., ACCTRAN), and the ala; is the best mechanical way of finding the minimal • Alar depression - a depressed area anterior to the tree (Williams 1996). Standard parsimony ala, adaxial to axial furrow; analyses are run using the same settings in • Posterior alar depression - depressed area NONA as in the three-item analysis and included posterior to ala, proximal to posterior border. for comparison. Character states are optimised onto standard Function of the Harpetid Brim parsimony and three-item trees using WINCLADA The harpetid brim has been described variously version 0.9 (Nixon 1999). Characters optimised onto as functioning like a plough (Dollo 1909, Staff and standard parsimony trees give inference to Reck 1911), as a sieving or hydrostatic device character transformations on the first tree. The first (Rouault 1847, Richter 1920), or as a is chosen by default for each analysis. Optimised strengthening and lightening function (Miller character states on three-item minimal trees provide 1972), or as a respiratory (Jell 1978) or sensory no information regarding character transformations organ (Whittington 1950a). Despite the very due to the nature of implementation (see Kitching et variable interpretations, they do highlight the al. 1998: 167-186). significance of the coarse pitting and/or caeca as The characters coded for cladistic analysis were being the primary functional organs of the fringe. taken from both specimens and photographs. With this assumption in mind, the presence of Specimens were painted with carbon, and then both pits and caeca on the brim indicate a coated with ammonium chloride, in order to attain functioning brim. Coarse pitting and caeca are high quality, contrasting photographs. herein regarded as being both a valid structure for cladistic analysis and as a possible 'functional organ'. Fine pitting or granules do not serve as SYSTEMATIC PALAEONTOLOGY homologous functional organs and are herein defined as 'ornament'. Terminology Cephalic nomenclature used herein follows Material Whittington (1950a, fig I, 1959, fig. 85, 1997). Figured specimens used in this study are held However, it should be noted that in Whittington as follows: GLAHM, Hunterian Museum, (1959, fig. 85) there are two inaccuracies, arising Glasgow, u.K.; MBT, Museum of Natural History, from the redrawing of Whittington (1950a, fig.1). Humbolt University, Berlin, Germany; Department The line for the brim prolongation is too long, and of Palaeontology, Natural History Museum, points to the genal roll prolongation. The line for London, U.K.; NIGP, Nanjing Institute of the genal roll prolongation is too short and points to Geology and Palaeontology, Academia Sinica, the internal rim of the prolongation, rather than to Nanjing, China; NM, Department of the genal roll prolongation. Palaeontology, National Museum, Prague, Czech Due to the unique cephalic features of harpetids Republic; NMV, Department of Invertebrate and the ambiguity of some of the terms, a revised Palaeontology, Museum Victoria, Melbourne, version of cephalic features is given in Figure 1 Australia; SM, Senckenberg Museum, Frankfurt, herein. In this revision it is essential to introduce Germany; UUG, Czech Geological Survey, Prague, some new terms to cover morphological features Czech Republic; WAM, Department of Earth and that have not been previously named. These are: Planetary Sciences, Western Australian Museum, • Girder kink - a sagittal deflection of the girder, Perth, Australia. Systematics of the Harpetidae 237 Exsagittal Sagittal -------------------------------~--~~---=~--------------------Rim Girder kink Anterior boss -r--'r...::..."",.-------~------- Preglabellar depression .s::. Transverse preglabellar ridge Cl .....------.1,;---- Girder -c: 1Il /j~""""---,.,..--".:-----~------'~-Preglabellar