Paradoxides Brongniart, 1822

Unger, Tanja, Hildenbrand, Anne, Stinnesbeck, Wolfgang & Austermann, Gregor, 2022, Biostratigraphy and taxonomy of polymerid trilobites of the Manuels River Formation (Drumian, middle Cambrian), Newfoundland, Canada, Geodiversitas 44 (33), pp. 1051-1087 : 1067

Genus Paradoxides Brongniart, 1822

Paradoxides Brongniart, 1822: 8 . —

Type species: Entomostracites paradoxissimus Wahlenberg, 1821 , by subsequent designation by Poulsen (1956).

DIAGNOSIS. — Rounded anterior margin, S2 transglabellar, S3 and S4 short; palpebral lobe short, from S1 to S3; anterior and posterior section of facial suture moderately to strongly divergent; thorax with 19-21 segments; pleural spines progressively directed more strongly backwards, hindmost pairs of pleural spines increase in length, ending behind pygidial margin; pygidium small, subcircular to quadrat (based on Whittington et al. 1997; Fletcher et al. 2005, with modifications).

REMARKS

The genus Paradoxides Brongniart, 1822 , and the family Paradoxididae Hawle & Corda, 1847 , need comprehensive revision, as pointed out by e.g., Sdzuy (1967), Geyer (1998), Geyer & Landing (2001), Kim et al. (2002) and Żylińska & Masiak (2007). According to Żylińska & Masiak (2007), the main problem within Paradoxides are different characters for subdividing the species, such as subdivisions based on holaspid forms, in contrast to ontogenetic differences in protaspid and holaspid forms. Šnajdr (1958) mentioned a wide range in opinions (e.g., Pompeckj 1896; Raymond 1914) regarding the ontogenetic development of Czech Paradoxides . As discussed by Whittington et al. (1997), many specimens assigned to Paradoxides are too poorly preserved to be determined confidently, leading to several species being based on poorly preserved material ( Šnajdr 1958; Geyer 1998). According to Geyer & Landing (2001) there are more than 100 species and subspecies of Paradoxides sensu lato.

Šnajdr (1958) classified Paradoxides Brongniart, 1822 ; Hydrocephalus Barrande, 1846 ; Eccaparadoxides Šnajdr, 1957 ; and Acadoparadoxides Šnajdr, 1957 , as genera of the Paradoxididae . Several authors followed this subdivision and included other genera as, for example, Plutonides Hicks, 1895 (e.g., Martinsson 1974; Whittington et al. 1997; Kim et al. 2002; Dean 2005; Rushton & Weidner 2007; Rushton et al. 2016). Others ranked clades as Hydrocephalus , Eccaparadoxides , Acadoparadoxides , and Plutonides as subgenera of Paradoxides (e.g., Solov’ev 1981; Martin & Dean 1988; Geyer 1998; Geyer & Landing 2001; Fletcher et al. 2005; Żylińska & Masiak 2007) and introduced new clades such as Paradoxides (Mawddachites) Fletcher, 2007 ( Fletcher 2007) . Kim et al. (2002) mentioned that diagnostic characteristics of (sub)genera differ substantially among authors. Here we apply the subdivision established by Whittington et al. (1997) following Šnajdr (1958).